CN101166054B - MIMO WLAN systems - Google Patents
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Abstract
The invention relates to a multiple-access MIMO WLAN system that employs MIMO, OFDM, and TDD. The system (1) uses a channel structure with a number of configurable transport channels, (2) supports multiple rates and transmission modes, which are configurable based on channel conditions and user terminal capabilities, (3) employs a pilot structure with several types of pilot (e.g., beacon, MIMO, steered reference, and carrier pilots) for different functions, (4) implements rate, timing, and power control loops for proper system operation, and (5) employs random access for system access by the user terminals, fast acknowledgment, and quick resource assignments. Calibration may be performed to account for differences in the frequency responses of transmit/receive chains at the access point and user terminals. The spatial processing may then be simplified by taking advantage of the reciprocal nature of the downlink and uplink and the calibration.
Description
The application is to be application number the dividing an application for the Chinese patent application of " MIMO wlan system " that be No. 200380104560.1 denomination of invention on October 24th, 2003 applying date.
Require priority according to 35U.S.C. § 119
The application requires the priority of the 60/421st, No. 309 U.S. Provisional Patent Application, and the latter is entitled as " MIMOWLAN system ", submits on October 25th, 2002.
Background
Technical field
The present invention relates generally to data communication, relate in particular to a multiple-input and multiple-output (MIMO) WLAN (wireless local area network) (WLAN) communication system.
Background technology
Wireless communication system is widely used for providing various types of communication such as voice, grouped data.These systems can be can by share that available system resource is supported sequentially or simultaneously with the multi-address system of a plurality of telex networks.The example of multi-address system comprises code division multiple access (CDMA) system, time division multiple access (TDMA) system and frequency division multiple access (FDMA) system.
WLAN (wireless local area network) (WLAN) also is widely used in the communication that allows via Radio Link between radio-based electronic devices (for example computer).WLAN can adopt the access point (or base station) of working as hub, and provides connection for wireless device.Access point also can be linked WLAN (or " bridge joint ") wired lan, thereby makes wireless device can access the LAN resource.
In wireless communication system, can be by a plurality of propagation paths arrival receiver units from radio frequency (RF) modulated signal of transmitter unit.Because factors such as decline and multipath, the feature of propagation path can change along with the time.In order to provide with respect to the diversity of abominable path effects and to improve performance, can use many and transmit and receive antenna.If the propagation path that transmits and receives between the antenna is Line independent (i.e. transmission on the paths is not the combination of transmitting on other paths), this sets up at least to a certain extent, then along with the increase of antenna amount, the probability that correctly receives transfer of data also improves.Generally speaking, along with the increase that transmits and receives antenna amount, diversity also increases, and performance also is improved.
Mimo system adopts many (N
T) transmitting antenna and Duo Gen (N
R) reception antenna carries out transfer of data.By N
TTransmit antennas and N
RThe mimo channel that the root reception antenna forms can be broken down into N
SIndividual space channel, N
S≤ min{N
T, N
R.N
SEach of individual space channel is corresponding to a dimension.If use many to transmit and receive the additional dimension that antenna creates, mimo system just can provide improved performance (transmission capacity that has for example improved and/or higher reliability).
The resource of one given communication system generally is subject to various regulations constraints and other actual Considerations are limit.Yet, may require system to support a plurality of terminals, various services are provided, realize specific performance objective etc.
Therefore, the MIMO wlan system that needs to support a plurality of users in this area and high systematic function is provided.
Summary of the invention
A kind of various abilities and can realize high performance multiple access MIMO wlan system of having have been described here.In one embodiment, system adopt MIMO and OFDM (OFDM) keep high-throughput, to the path effects of degeneration and other benefits are provided.Each access point in the system can be supported a plurality of user terminals.The resource of down link and up link is distributed requirement, channel condition and other factor that depends on user terminal.
The channel architecture of supporting effective down link and ul transmissions also is provided here.Channel architecture comprises a plurality of transmission channels that can be used for a plurality of functions, signaling, down link and the uplink data transmission that described a plurality of function ratio such as system parameters and resource are distributed, random access of system etc.The various attributes of these transmission channels are configurable, and this makes system easily channel and the loading condition of Adaptive change.
The MIMO wlan system supports a plurality of speed and transmission mode in order to keep high-throughput when channel condition and ability of user terminal support.Speed can be based on the estimation of channel condition and is configured, and can independently select for down link and up link.Also can use different transmission modes, this depends on number of antennas and the channel condition at user terminal place.The different spaces at each transmission mode and transmitter and receiver place is processed and is associated, and can be selected under the different conditions of work and use.For higher throughput and/or diversity, spatial manipulation is convenient to from the transfer of data of many transmit antennas and/or with the data receiver of many reception antennas.
In one embodiment, the MIMO wlan system is that down link and up link are used single frequency band, and down link and up link use time division duplex (TDD) to share same working band.For the TDD system, down link and uplink channel responses are reciprocal.Here provide collimation technique to determine and remedy the difference of frequency response of access point and user terminal place transmit/receive chains.The reciprocal characteristic of utilizing down link and up link and the technology of calibrating the spatial manipulation of simplifying access point and user terminal place have also been described here.
Pilot configuration with the used a few class pilot tones of difference in functionality also is provided.For example, can use the MIMO pilot tone for channel estimating for frequency and system acquisition use beacon pilot frequency, can use controlled index (being controlled pilot tone) for improved channel estimating, and can use carrier pilot for Phase Tracking.
The various control loops that are used for the operation of correct system also are provided.Can on down link and up link, carry out independently speed control.Can carry out power control for specific transmission (for example service of fixed rate).Can remedy for ul transmissions the different propagation delays of residing user terminal in the system with timing controlled.
The random access technology that makes user terminal energy connecting system also is provided.The a plurality of user terminals of these technical supports are to the access of system, the quick affirmation of system access trial and the fast allocation of downlink/uplink resource.
The below has been described in further detail various aspects of the present invention and embodiment.
Description of drawings
In the detailed description that proposes by reference to the accompanying drawings below, feature of the present invention and character will become more apparent, and identical reference number represents identical element in the accompanying drawing, wherein:
Fig. 1 illustrates a MIMO wlan system;
Fig. 2 illustrates the layer structure of MIMO wlan system;
Fig. 3 A, 3B and 3C illustrate respectively TDD-TDM frame structure, FDD-TDM frame structure and FDD-CDM frame structure;
Fig. 4 illustrates the TDD-TDM frame structure of five transmission channel-BCH, FCCH, FCH, RCH and RACH;
Fig. 5 A illustrates variety of protocol data cell (PDU) form of five transmission channels to 5G;
Fig. 6 illustrates a kind of structure of FCH/RCH grouping;
Fig. 7 illustrates an access point and two user terminals;
Fig. 8 A, 9A and 10A illustrate three transmitter units that are respectively applied to diversity mode, space multiplexing mode and wave beam control model;
Fig. 8 B, 9B and 10B illustrate three transmit diversity processors that are respectively applied to diversity mode, space multiplexing mode and wave beam control model;
Fig. 8 C illustrates an OFDM modulator;
Fig. 8 D illustrates an OFDM code element;
Figure 11 A illustrates framing unit and the disarrangement device in the transmit data processor;
Figure 11 B illustrates encoder and the repetition/brachymemma unit in the transmit data processor;
Figure 11 C illustrates another transmit data processor that can be used for space multiplexing mode;
Figure 12 A and 12B illustrate the state diagram for user terminal operations;
Figure 13 illustrates the timeline of RACH;
Figure 14 A and 14B illustrate the process of the transmission rate that is respectively applied to control down link and up link;
Figure 15 illustrates the operation of power control circuit; And
Figure 16 illustrates the process for the up link sequential of regulating user terminal.
Describe in detail
Here use word " exemplary " to mean " serving as example, example or explanation ".Here any embodiment that is described as " exemplary " needn't be regarded as more more preferred or favourable than other embodiment or design.
1. total system
I. total system
Fig. 1 illustrates the MIMO wlan system 100 of supporting a plurality of users and realizing various aspects embodiment of the present invention.MIMO wlan system 100 comprises a plurality of access points (AP) 110 of the communication of supporting a plurality of user terminals.For simplicity, two access points 110 only are shown among Fig. 1.Access point generally is for the fixed station that communicates with user terminal.Access point also can be called base station or some other term.
User terminal 120 can spread in the system.Each user terminal can be the fixing or mobile terminal that can communicate by letter with access point.User terminal also can be called mobile radio station, distant station, accesses terminal, subscriber equipment (UE), wireless device or some other term.Each user terminal can may communicate by a plurality of access points with one on down link and/or up link at arbitrary given time.Down link (being forward link) refers to the transmission from the access point to the user terminal, and up link (being reverse link) refers to the transmission from the user terminal to the access point.
Among Fig. 1, access point 110a communicates by letter with user terminal 120a by 120f, and access point 110b communicates by letter with user terminal 120f by 120k.According to the particular design of system 100, access point is (for example by a plurality of encoding channels or subchannel) or sequentially (for example via a plurality of time slots) and a plurality of user terminals communicate simultaneously.In arbitrary given moment, user terminal can receive the downlink transmission from one or more access points.From the downlink transmission of each access point can comprise will by overhead data that a plurality of user terminal received, will be by the customer-specific data that specific user terminal received, the data of other type or their arbitrary combination.Overhead data can comprise pilot tone, paging and broadcast, system parameters etc.
The MIMO wlan system is based on a central authoritiesization controller network structure.Like this, system controller 130 is coupled to access point 110, further is coupled to other System and Network.For example, system controller 130 can be coupled to packet data network (PDN), cable LAN (LAN), wide area network (WAN), the Internet, public switch telephone network (PSTN), cellular communications network etc.System controller 130 can be designed to a plurality of functions, such as (1) to coordination and the control of the access point of its coupling, (2) route data between these access points, (3) access is communicated by letter with control and these access points user terminal of serving, etc.
Compare with conventional wlan system, perhaps the MIMO wlan system can provide covering power much bigger high-throughput.The MIMO wlan system can be supported synchronous, asynchronous with etc. the time the data/voice service.The MIMO wlan system can be designed to provide following characteristics:
High service reliability
Guaranteed service quality (QoS)
High instantaneous data rates
Spectral efficient
The coverage of expansion.
The MIMO wlan system can be operated in each frequency band (for example 2.4GHz and 5.xGHz U-NII frequency band), is subjected to bandwidth and radiation limitations for selected working band special use.System is designed to support the use of indoor and outdoors, and general maximum cell size is 1km or still less.The terminal applies that system's support is fixing, however a few thing pattern is also supported portable and limited move operation.
1.MIMO, MISO and SIMO
In certain embodiments, and as described in this specification, each access point is equipped with four and transmits and receives antenna and carry out data input and data output, wherein comes sending and receiving with four identical antennas.System is transmitting antenna and the not shared situation of reception antenna of support equipment (for example access point, user terminal) also, even lower performance is provided when the common ratio antenna of this configuration is shared.The MIMO wlan system can also design like this: so that each access point is equipped with the transmit/receive antenna of some other quantity.Each user terminal can be equipped with single transmit/receive antenna or many transmit/receive antennas carry out data input and data output.The antenna amount that each type of user terminal adopts depends on various factors, the service of supporting such as user terminal (for example voice, data or both), cost consideration, regulations constraint, safety problem etc.
For given one-to-many antenna access point and many antennas user terminal, mimo channel is by the N that can be used for transfer of data
TTransmit antennas and N
RThe root reception antenna forms.Between access point and different many antennas user terminal, form different mimo channels.Each mimo channel can be broken down into N
SIndividual space channel, N
S≤ min{N
T, N
R.N
SIndividual data flow can be at N
SBe sent out on the individual space channel.Require spatial manipulation at the receiver place, may or may not carry out spatial manipulation at the transmitter place so that at N
SThe a plurality of data flow of emission on the individual space channel.
N
SIndividual space channel possibility is orthogonal or possibility is non-orthogonal.This depends on various factors, whether carries out spatial manipulation such as (1) at the transmitter place for obtaining orthogonal spatial channels, and (2) whether both locate to carry out spatial manipulation at transmitter and receiver when making space channel orthogonalization.If do not carry out spatial manipulation, then N at the transmitter place
SIndividual space channel can be used N
STransmit antennas is carried out, and can not be orthogonal.
As described below, decompose N by the channel response matrix to mimo channel
SIndividual space channel can quadrature.If N
SIndividual space channel uses and decomposes and quadrature, and then each space channel is called the eigenmodes of mimo channel, decomposes the spatial manipulation that requires the transmitter and receiver place.In this case, N
SIndividual data flow can be at N
SQuadrature sends on the individual eigenmodes.Yet eigenmodes generally refers to theoretical construct.Since a variety of causes, N
SIndividual space channel generally is not fully orthogonal.For example, if (1) transmitter is known mimo channel, perhaps (2) transmitter and/or receiver have the incomplete estimation of mimo channel, and then space channel can quadrature.For simplicity, in the following description, term " eigenmodes " is used for representing to attempt with decomposing the orthogonalized situation of space channel that makes, even attempt because former thereby incomplete successes such as incomplete channel estimating.
For the antenna of access point place to determined number (for example four), each user terminal can with number of spatial channels depend on the number of antennas that user terminal adopts and the feature of the Technique of Wireless MIMO Channel of be coupled access point antenna and user terminal antenna.If user terminal is equipped with an antenna, then the single antenna at four of access point place antennas and user terminal place has formed the single delivery channel of many inputs (MISO) of down link and single input multiple-output channel (SIMO) of up link.
The MIMO wlan system can be designed to support multiple transmission mode.Table 1 is listed the transmission mode of being supported by the exemplary design of MIMOWLAN system.
Table 1
For simplicity, term " diversity " refers to send diversity in the following description, unless specialize.
The down link of each user terminal and up link can with transmission mode depend on the number of antennas that the user terminal place adopts.Table 2 is listed the transmission mode that the different terminals type of down link and up link can be used, and supposing has many (for example four) antennas at the access point place.
Table 2
For down link, all transmission modes except space multiplexing mode all can be used for the single antenna user terminal, and all transmission modes all can be used for many antennas user terminal.For up link, all transmission modes can be used by many antennas user terminal, and the single antenna user terminal uses the MIMO pattern to send data from an available antenna.Receive diversity (namely with many reception antenna receive data transmission) can be used for SIMO, diversity and wave beam control model.
The MIMO wlan system also can be designed to support various other transmission modes, and this within the scope of the invention.For example, the beam forming pattern can be used to send data in single eigenmodes, used the amplitude of this eigenmodes and phase information (rather than only use phase information, the latter be the wave beam control model all use).For another example, can define a kind of " uncontrolled " space multiplexing mode, wherein transmitter only sends a plurality of data flow (not carrying out any spatial manipulation) from many transmit antennas, and necessary spatial manipulation carried out by receiver so that the data flow that isolation and recovery send from many transmit antennas.For also having an example, can define a kind of " multi-user " space multiplexing mode, wherein access point sends to a plurality of user terminals (using spatial manipulation) to a plurality of data flow from many transmit antennas concurrently on up link.For an example is arranged again, can define a kind of space multiplexing mode, wherein transmitter is carried out spatial manipulation to attempt that a plurality of data flow that send on many transmit antennas are carried out orthogonalization (but possibility not exclusively success owing to incomplete channel estimating), and receiver is carried out requisite space and processed to isolate and recover from the data flow of many transmit antennas transmissions.Like this, for the spatial manipulation of carrying out via a plurality of data flow of many radical spaces channels transmit can carried out with upper/lower positions: (1) at both places of transmitter and receiver, (2) only at the receiver place, perhaps (3) are only at the transmitter place.Can use different spatial reuses according to following factor, for example the ability of access point and user terminal, available channel condition information, system requirements etc.
Usually, access point and user terminal can be designed to any amount of transmitting antenna and reception antenna.For simplicity, be described below specific embodiment and design, wherein each access point is equipped with four transmit/receive antennas, and each user terminal is equipped with four or less transmit/receive antenna.
2.OFDM
In one embodiment, the MIMO wlan system adopts OFDM that the total system bandwidth is divided into a plurality of (N effectively
F) orthogonal subbands.These subbands also can be called as tone, frequency band or frequency channels.According to OFDM, each subband is associated with corresponding subcarrier, and subcarrier can be modulated with data.For the mimo system that uses OFDM, each space channel of each subband can be regarded as a transmission channel independently, and the complex gain that is associated with each subband whereby is constant on the subband bandwidth.
In one embodiment, to be divided into 64 orthogonal subbands (be N to system bandwidth
F=64), be assigned to index-32 to+31.In these 64 subbands, for data use 48 subbands (for example index be ± 1 ...; 6,8 ...; 20; 22 ..., 26}); for pilot tone and possible signaling use 4 subbands (for example index be ± { 7; 21}), DC subband (index is 0) does not use, and the subband of adventure does not use yet and serves as the protection subband.This OFDM sub band structure is described in further detail in the document of ieee standard 802.11a, the document is entitled as " Part 11:Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications:High-Speed Physical Layer in the 5GHz Band; " propose in September, 1999, it can obtain for the public, and incorporated herein by reference.Also can use subband and various other OFDM sub band structure of varying number for the MIMO wlan system, this within the scope of the invention.For example, can make for transfer of data whole 53 index of index of reference from-26 to+26.For another example, can use the structure of 128 subbands, the structure of 256 subbands and the sub band structure with some other numbers of sub-band.For clear, the MIMO wlan system with above-mentioned 64 sub band structure is described below.
For OFDM, at first modulate (being symbol mapped) with a certain modulation schemes of selecting for this subband in the data that each subband sends.For untapped subband provides null value.For each code-element period, whole N
FThe modulated symbol of individual subband and null value all use invert fast fourier transformation (IFFT) to transform to time domain, in order to obtain to comprise N
FThe conversion code element of individual time-domain sampling.The duration of each conversion code element is inversely related with the bandwidth of each subband.In a particular design of MIMO wlan system, system bandwidth is 20MHz, N
F=64, the bandwidth of each subband is 312.5KHz, and the duration of each conversion code element is 3.2 microseconds.
OFDM can provide specific advantage, and the ability such as the decline of contrary frequency selectivity is characterized in that at the different frequency place of total system bandwidth different channel gains being arranged.Be well known that, frequency selective fading causes the interference (ISI) between code element, and ISI is that each code element that receives in the signal is served as to received signal a kind of phenomenon of the interference of middle subsequent symbol.The ISI distortion makes performance degradation by the ability that impact is correctly decoded receiving symbol.Part by repeating each conversion code element (or adhere to a Cyclic Prefix to it) forms corresponding OFDM code element, can easily tackle frequency selective fading with OFDM, and corresponding OFDM code element is sent out subsequently.
The length of the Cyclic Prefix of each OFDM code element (amount that namely will repeat) depends on the delay expansion of wireless channel.Particularly, in order effectively to resist ISI, it is long that Cyclic Prefix should postpone expansion than the greatest expected of system.
In one embodiment, can use for the OFDM code element Cyclic Prefix of different length, this depends on the delay expansion of expection.For above-mentioned specific MIMO wlan system, can select for 400 nanoseconds for the OFDM code element Cyclic Prefix of (8 samplings) or 800 nanoseconds (16 samplings)." short " OFDM code element is used the Cyclic Prefix of 400 nanoseconds, and the duration is 3.6 microseconds." length " OFDM code element is used the Cyclic Prefix of 800 nanoseconds, and the duration is 4.0 microseconds.If the delay of greatest expected expansion then can be used short OFDM code element less than or equal to 400 nanoseconds, if postpone expansion greater than 400 nanoseconds, then can use long OFDM code element.Can select different Cyclic Prefix for different transmission channels, Cyclic Prefix also can dynamically be selected, and is as described below.By may the time use shorter Cyclic Prefix can realize higher throughput of system because in a given Fixed Time Interval, can send shorter OFDM code element of more durations.
The MIMO wlan system can be designed to not use OFDM, and this within the scope of the invention.
The layer structure
Fig. 2 has illustrated the layer structure 200 that can be used for the MIMO wlan system.Layer structure 200 comprises: (1) approximate the 3rd layer of application and higher level protocol that reaches with upper strata (higher level) corresponding to the ISO/OSI reference model, (2) corresponding to agreement and the service of the 2nd layer (link layer), and (3) are corresponding to agreement and the service of the 1st layer (physical layer).
Higher level comprises various application and agreement, such as signaling service 212, data, services 214, voice service 216, circuit data applications etc.Signaling generally is provided as message, and data generally are provided as grouping.Service in the higher level and the meaning of one's words and the sequential used according to communication protocol between access point and the user terminal begin and termination messages and grouping.Higher level is provided by the 2nd layer of service that provides.
Support message that higher level generates and the transmission of grouping for the 2nd layer.In the embodiment shown in Figure 2, the 2nd layer comprises link access control (LAC) sublayer 220 and medium access control (MAC) sublayer 230.LAC has realized the sublayer SDL, and the message that higher level generates can correctly be transmitted and transmit to this agreement.Media access control sublayer and the 1st layer of service that provides are provided in the LAC sublayer.Media access control sublayer is responsible for coming message transfer and grouping with the 1st layer of service that provides.Application and service in the media access control sublayer control RLP higher level processed is to the access of the 1st layer of resource.Media access control sublayer can comprise radio link protocol (232), and this agreement is used to the retransmission mechanism that grouped data provides higher reliability.The 2nd layer provides protocol Data Unit (PDU) to the 1st layer.
The 1st layer of sending and receiving that comprises physical layer 240 and support wireless signal between access point and the user terminal.Physical layer is carried out for each transmission channel and is encoded, interweaves, modulation and spatial manipulation, and described transmission channel is used for sending message and the grouping that higher level generates.In this embodiment, physical layer comprises a multiplex sublayer 242, and multiplex sublayer 242 is multiplexed into correct frame format to the PDU that processes for each transmission channel.The 1st layer provides data take frame as unit.
Fig. 2 illustrates the specific embodiment of the layer structure that can be used for the MIMO wlan system.Can also and use various other suitable layer structures for the MIMOWLAN system, this within the scope of the invention.Every layer of performed function is described in further detail below.
4. transmission channel
A plurality of services and application can be supported by the MIMO wlan system.In addition, other required data of correct system's operation may be sent and be exchanged between access point and user terminal by access point.Can define a plurality of transmission channels in order to transmit Various types of data for the MIMO wlan system.Table 3 is listed one group of exemplary transmission channel, and the concise and to the point description of each transmission channel also is provided.
Table 3
As shown in table 3, the employed downlink transmission channel of access point comprises BCH, FCCH and FCH.The employed uplink transmission channels of user terminal comprises RACH and RCH.Each of these transmission channels is described in further detail below.
The transmission channel of listing in the table 3 has represented to can be used for a specific embodiment of the channel architecture of MIMO wlan system.Also can be for the use definition of MIMO wlan system is less, additional and/or different transmission channel.For example, specific function can be supported by the transmission channel (for example pilot tone, paging, power control and synchronizing channel) of function special use.Like this, can be other channel architecture that the MIMO wlan system defines and use has different transmission channel groups, this within the scope of the invention.
5. frame structure
Can define a plurality of frame structures for transmission channel.The particular frame structure that will be used for the MIMO wlan system depends on various factors, be that down link uses identical or different frequency bands with up link such as (1), and (2) is used for the multiplexing multiplexing scheme together of transmission channel.
If only there is a frequency band to use, then can use time division duplex (TDD) to send down link and up link in the out of phase of a frame, as described below.If there are two frequency bands to use, then use Frequency Division Duplexing (FDD) (FDD) to send down link and up link at different frequency bands.
For TDD and FDD, transmission channel can be multiplexed in together with time division multiplexing (TDM), code division multiplexing (CDM), frequency division multiplexing (FDM) etc.For TDM, each transmission channel is assigned to a different piece of a frame.For CDM, transmission channel is sent out concurrently, but each transmission channel comes channelizing by a different channelization code, is similar to the channelizing of carrying out in code division multiple access (CDMA) system.For FDM, each transmission channel is assigned to a different piece of link frequency bands.
Table 4 is listed the various frame structures that can be used to transmit transmission channel.Each of these frame structures is described in further detail below.For clear, for this group transmission channel of listing in the table 3 has been described frame structure.
Table 4
Fig. 3 A has illustrated the embodiment of a TDD-TDM frame structure 300a, and this structure can be used when using single frequency band for down link and up link.Transfer of data occurs take tdd frame as unit.Each tdd frame can be defined as striding across a special time duration.The frame duration can be selected based on various factors, the bandwidth of (1) working band for example, desired size of the PDU of (2) transmission channel etc.Usually, the shorter frame duration can provide the delay of minimizing.Yet the long frame duration may be more effective, because header and expense can represent the smaller portions of a frame.In a specific embodiment, the duration of each tdd frame is 2 milliseconds.
Each tdd frame is divided into down link phase place and up link phase place.For three downlink transmission channel-BCH, FCCH and FCH, the down link phase place further is divided into three segmentations.For two uplink transmission channels-RCH and RACH, the up link phase place further is divided into two segmentations.
The fixedly duration that the segmentation of each transmission channel can be defined as changing frame by frame or variable duration.In one embodiment, the BCH segmentation has been defined as fixing duration, and FCCH, FCH, RCH and RACH segmentation have been defined as the variable duration.
The segmentation of each transmission channel can be used to transmit the one or more protocol Data Units (PDU) for this transmission channel.In the specific embodiment shown in Fig. 3 A, in the down link phase place, BCH PDU is sent out in the first segmentation 310, and FCCH PDU is sent out in the second segmentation 320, and one or more FCH PDU are sent out in the 3rd segmentation 330.On the up link phase place, one or more RCH PDU are sent out in the 4th segmentation 340, and one or more RACH PDU are sent out in the 5th segmentation 350 of tdd frame.
Fig. 3 B has illustrated the embodiment of the FDD-TDM frame structure 300b that may use when using two frequency bands that separate to send down link and up link.Down link data is sent out in descending chain circuit frame 302a, and uplink data is sent out in uplink frame 302b.Each down link and uplink frame can be defined the specific time remaining phase (for example 2 milliseconds) that strides across.For simplicity, down link can be defined as having the identical duration with uplink frame, and further is defined on the frame boundaries and aligns.Yet, also can use for down link and up link (i.e. skew) frame boundaries of different frame durations and/or non-alignment.
Shown in Fig. 3 B, for three downlink transmission channel, descending chain circuit frame is divided into three segmentations.For two uplink transmission channels, uplink frame is divided into two segmentations.The segmentation of each transmission channel can be defined as the fixing or variable duration, and can be used for transmitting one or more PDU for this transmission channel.
In the specific embodiment shown in Fig. 3 B, descending chain circuit frame transmits respectively BCH PDU, a FCCH PDU and one or more FCH PDU in segmentation 310,320 and 330.Uplink frame transmits respectively one or more RCH PDU and one or more RACH PDU in segmentation 340 and 350.This particular topology can provide the above-mentioned benefit delay of the minimizing of transfer of data (for example for).As described below, transmission channel may have different PDU forms.Also can define and use for the MIMO wlan system other FDD-TDM frame structure, this within the scope of the invention.
Fig. 3 C has illustrated when down link and up link use frequency band separately to send the also embodiment of operable FDD-CDM/FDM frame structure 300c.Down link data can be sent out in descending chain circuit frame 304a, and uplink data can be sent out in uplink frame 304b.Down link can be defined as the identical duration (for example 2 milliseconds) and align at the frame boundaries place with uplink frame.
Shown in Fig. 3 C, in descending chain circuit frame, send concurrently three downlink transmission channel, in uplink frame, send concurrently two uplink transmission channels.For CDM, the transmission channel of each link comes " channelizing " with different channelization code, and described channelization code can be Walsh code, orthogonal variable spreading factor (OVSF) code, class orthogonal function (QOF) etc.For FDM, the transmission channel of each link is assigned to the different piece of this link frequency bands.Also can use for the different transmission channels in each link the transmitted power of varying number.
Also can use other frame structure for down link and uplink transmission channels, this within the scope of the invention.In addition, may be down link and the dissimilar frame structure of up link use.For example, can be the frame structure of down link use based on TDM, and be that up link is used the frame structure based on CDM.
In the following description, suppose that the MIMO wlan system is that down link and ul transmissions are used a frequency band.For clear, the TDD-TDM frame structure shown in Fig. 3 A is used for the MIMO wlan system.For clear, the specific implementation of TDD-TDM frame structure is described in this manual.Realize for this, the duration of each tdd frame is fixed to 2 milliseconds, and the OFDM number of symbols of every tdd frame is the function of the used paging prefix length of OFDM code element.The fixedly duration of BCH is 80 microseconds, and is that the OFDM code element of launching is used the paging prefix of 800 nanoseconds.If use the paging prefix of 800 nanoseconds, then the remainder of tdd frame comprises 480 code elements, if use the Cyclic Prefix of 400 nanoseconds, then the remainder of tdd frame comprises the excessive time that 533 OFDM code elements add 1.2 microseconds.This excessive time can be added in the end of RACH segmentation the protection interval.Also can use other frame structure and other realization, this within the scope of the invention.
II. transmission channel
Transmission channel is used for sending Various types of data, and can be classified as two groups: Common transport channel and dedicated transmission channel.Owing to having used public and dedicated transmission channel for different purposes, therefore can use different processing, following being described in further detail for these two groups of transmission channels.
Common transport channel.Common transport channel comprises BCH, FCCH and RACH.These transmission channels are used for that data are sent to a plurality of user terminals or from a plurality of user terminal receive datas.For improved reliability, BCH and FCCH are sent with diversity mode by access point.On up link, RACH is sent with wave beam control model (if user terminal support) by user terminal.BCH is with known fixed rate work, so that user terminal can need not any additional information receive and treatments B CH.FCCH and RACH support a plurality of speed to allow higher efficient.As used herein, each " speed " or " rate set " are associated with a specific code rate (or encoding scheme) and a specific modulation scheme.
Dedicated transmission channel.Dedicated transmission channel comprises FCH and RCH.These transmission channels are commonly used to customer-specific data is sent to specific user terminal.As required with according to available situation, FCH and RCH can be dynamically allocated to user terminal.FCH can also be used for an expense, paging and broadcast and send to user terminal in broadcast mode.Usually, before the arbitrary customer-specific data on the FCH, send expense, paging and broadcast.
Fig. 4 has illustrated the exemplary transmission on BCH, FCCH, FCH, RCH and RACH based on TDD-TDM frame structure 300a.In this embodiment, a BCH PDU 410 and a FCCH PDU 420 are sent out in BCH segmentation 310 and FCCH segmentation 320 respectively.FCH segmentation 330 can be used for sending one or more FCH PDU 430, and each FCH PDU 430 can point to a specific user terminal or a plurality of user terminal.Similarly, one or more RCH PDU 440 can be sent out in RCH segmentation 340 by one or more user terminals.The beginning of each FCH/RCH PDU is offset to represent by the FCH/RCH from last segmentation finishes.RACH PDU 450 can be sent in RACH segmentation 350 so that connecting system and/or send SMS message is as described below by a plurality of user terminals.
For clear, for the specific T DD-TDM frame structure shown in Fig. 3 A and 4 has been described transmission channel.
1. broadcast channel (BCH)-down link
Access point uses BCH that beacon pilot frequency, MIMO pilot tone and system parameters are sent to user terminal.User terminal comes capture systems sequential and frequency with beacon pilot frequency.User terminal is estimated the mimo channel that the antenna by access point antenna and they self forms with the MIMO pilot tone.The below is described in further detail beacon pilot frequency and MIMO pilot tone.System parameters has been specified each attribute of down link and ul transmissions.For example, because the duration of FCCH, FCH, RACH and RCH segmentation is variable, then in BCH, be sent as the system parameters that current tdd frame is specified the length of each in these segmentations.
Fig. 5 A has illustrated the embodiment of BCH PDU 410.In this embodiment, BCH PDU 410 comprises leader part 510 and message part 516.Leader part 512 also comprises beacon pilot frequency part 512 and MIMO pilot portion 514.Part 512 transmits beacon pilot frequency, and fixedly the duration is the TCP=8 microsecond.Part 514 transmits the MIMO pilot tone, and fixedly the duration is the TMP=32 microsecond.Part 516 transmits BCH message, and fixedly the duration is the TBM=40 microsecond.The duration of BCH PDU is fixed on the TCP+TMP+TBM=80 microsecond.
Leader can be used for sending pilot tone and/or the out of Memory of a class or multiclass.Beacon pilot frequency comprises the one group of specific modulated symbol that sends from whole transmitting antennas.The MIMO pilot tone comprises one group of specific modulated symbol of encoding and sending from whole transmitting antennas with different orthogonal, makes to receive the pilot tone that functional recovery sends from every antenna.For beacon and MIMO pilot tone can be used not on the same group modulated symbol.The generation of beacon and MIMO pilot tone is described in further detail below.
BCH message transfer service configuration information.Table 5 has been listed each field of an exemplary BCH message message format.
Table 5-BCH message
Frame counter can be used to each process (for example pilot tone, scrambler, overlay code etc.) at synchronous access point and user terminal place.Frame counter can be realized with 4 bit counter of wraparound.This counter increases one when the beginning of each tdd frame, Counter Value is included in the frame counter field.The network ID field has represented the identifier (ID) of access point belonging network.The AP id field has represented the ID of access point in the network ID.AP Tx Lvl and AP Rx Lvl field have represented respectively the maximum transit power level at access point place and the received power level of expectation.User terminal can be determined the initial uplink transmitted power with the received power level of expectation.
FCCH length, FCH length and RCH length field have represented respectively FCCH, the FCH of current tdd frame and the length of RCH field.The length of these fields provides take the OFDM code element as unit.The OFDM code element duration of BCH is fixed on 4.0 microseconds.The OFDM code element duration of all other transmission channels (being FCCH, FCH, RACH and RCH) all is variable, and depends on selected Cyclic Prefix, and Cyclic Prefix is specified by Cyclic Prefix duration field.The FCCH speed field has represented the employed speed of the FCCH of current tdd frame.
The RACH length field has represented the length of RACH field, and it provides take the RACH time slot as unit.The duration of each RACH time slot is provided by RACH time slot size field, and unit is the OFDM code element.RACH protection interval field has represented the time quantum of the BCH segmentation of a upper RACH time slot and next tdd frame between beginning.Each field of this of RACH is described in further detail below.
Paging bit and broadcasting bit have represented whether sent respectively beep-page message and broadcast on the FCH in current tdd frame.These two bits can be arranged independently for tdd frame.The RACH acknowledgement bit has represented that in current tdd frame FCCH sends before the tdd frame, whether sends the affirmation to PDU on RACH.
Crc field comprises the crc value of whole BCH message.The BCH message that this crc value can be used for determining receiving by user terminal is by correctly decoding (namely being) or by decode mistakenly (namely being wiped free of).The tail bit field comprises one group of null value, and this group null value is used in the end of BCH message convolution coder being reset to known state.
As shown in table 5, BCH message comprises altogether 120 bits.By using the processing of describing in detail below, these 120 bits can be sent out with 10 OFDM code elements.
Table 5 illustrates a specific embodiment of the form of BCH message.Can also define and use other BCH message format with less, additional and/or different field, this within the scope of the invention.
2. forward control channel (FCCH)-down link
In one embodiment, access point can frame by frame be FCH and RCH Resources allocation.Access point passes on the resource of FCH and RCH to distribute (being channel allocation) with FCCH-.
Fig. 5 B has illustrated the embodiment of FCCH PDU 420.In this embodiment, FCCH PDU only comprises the part 520 of FCCH message.FCCH message has the variable duration that can change along with the variation of frame, and this depends on the schedule information amount that transmits at the FCCH of this frame.The FCCH message duration is even number OFDM code element, and is provided by the FCCH length field on the BCH message.Use the duration of the message (for example BCH and FCCH message) of diversity mode transmission to provide with even number OFDM code element, because diversity mode sends the OFDM code element in couples, as described below.
In one embodiment, FCCH can send with four possible speed.The employed special speed of FCCH PDU represents with the FCCH multiplicative model in the BCH message (Phy Mode) field in each tdd frame.Each FCCH speed is corresponding to a specific code rate and a specific modulation scheme, and further is associated with specific transmission mode, and is shown in table 26.
FCCH message can comprise zero, one or more information element (IE).Each information element can be associated with a specific user terminal, and is used for providing the expression FCH/RCH information that resource is distributed for this user terminal.Table 6 has been listed each field of an exemplary FCCH message format.
Table 6-FCCH message
N_IE information element, each comprises:
The N_IE field shows the information element number that comprises in the FCCH message that sends in the current tdd frame.For each information element (IE) that comprises in the FCCH message, the IE type field shows the particular type of this IE.Defined a plurality of IE types and be used for as dissimilar transmission Resources allocation, as described below.
MAC IE field has represented the specific user terminal that information element is pointed.Each user terminal is registered to access point when communication session begins, and is access in and a little is assigned to unique MAC ID.This MAC ID is used for identifying subscriber terminal during session.
Control field is used for transmitting the channel allocation information of user terminal, and describes in detail below.The filling bit field comprises the filling bit of sufficient amount, so that the total length of FCCH message is even number OFDM code element.The FCCH crc field comprises a crc value, and user terminal can determine that the FCCH message that receives is correctly decoded or by decoded in error with described crc value.The tail bit field comprises for the null value that convolution coder is reset to known state in ending place of FCCH message.The below has been described in further detail some fields in these fields.
As shown in table 1, the MIMO wlan system is that FCH and RCH support a plurality of transmission modes.In addition, user terminal can be activity or idle during connecting., defined multiclass IE and be used for distributing the FCH/RCH resource into dissimilar transmission.Table 7 is listed one group of exemplary IE type.
Table 7-FCCH IE type
For IE type 0,1 and 4, for FCH and RCH distribute to specific user terminal (namely with channel form being distributed) to resource.For IE type 2, on FCH and RCH, minimum resource is distributed to user terminal to keep the latest estimated of link.The example format of each IE type is described below.Usually, the speed of FCH and RCH and duration can be distributed to user terminal independently.
Table 8- FCCH IE type 0 and 4
FCH and RCH offset field represent the time migration that minute is clipped to the beginning of FCH and RCH PDU of beginning from current tdd frame, are distributed by information element.FCH and RCH speed field represent respectively the speed of FCH and RCH.
FCH and RCH leader type field represent respectively the size of leader among FCH and the RCH PDU.Table 9 is listed FCH and the value of RCH leader type field and relevant leader size.
Table 9-leader type
RCH regularly regulates field and comprises regulating two bits from the timing of the ul transmissions of user's terminal by MAC id field sign.This regularly regulates to reduce the interference in the frame structure based on TDD (than frame structure as shown in Figure 3A), and wherein down link and ul transmissions are time division duplexs.Table 10 is listed RCH and is regularly regulated the value of field and relevant action.
Table 10-RCH regularly regulates
RCH power control field comprises regulating two bits from the transmitted power of the ul transmissions of institute's identifying subscriber terminal.This power control field is used for reducing the interference on the up link.Table 11 is listed the value and relevant action of RCH power control field.
Table 11-RCH decides power control
The channel allocation of institute's identifying subscriber terminal can provide in every way.In one embodiment, user terminal only is assigned to the FCH/RCH resource for current tdd frame.In another embodiment, before cancellation, for each tdd frame the FCH/RCH resource is distributed to terminal.In also having an embodiment, for every n tdd frame the FCH/RCH resource is distributed to user terminal, this is called as " extraction " scheduling of tdd frame.Dissimilar distribution can be shown by the distribution type field in the FCCH information element.
B.IE Class1-space multiplexing mode
IE Class1 usage space multiplexer mode is distributed to user terminal to the FCH/RCH resource.The speed of these user terminals is variable, and can select independently for FCH and RCH.Table 12 is listed each field of an exemplary IE Class1 information element.
Table 12-FCCH IE Class1
For the IE Class1, the speed of each space channel can be selected on FCH and RCH independently.The speed decipher of space multiplexing mode is normally because it can specify the speed (nearly four space channels being arranged for the embodiment shown in the table 12) of each space channel.If transmitter is carried out spatial manipulation in order to send data in eigenmodes, then provide speed according to each eigenmodes.If transmitter only sends data and receiver is carried out spatial manipulation so that isolation and recover data (for uncontrolled space multiplexing mode) then provides speed according to every antenna from transmitting antenna.
Information element comprises the speed of the space channel that all is activated, and is null value for the channel that is not activated.Have the user terminal that is less than four transmit antennas untapped FCH/RCH space channel speed field is made as zero.Because access point is equipped with four transmit/receive antennas, therefore has more than the user terminal of four transmit antennas and can launch nearly four independent data streams with them.
C.IE type 2-idle pulley
Table 13-FCCH IE type 2
D.IE type 3-RACH confirms fast
Table 14-FCCH ID type 3
Can define and send at FCCH the affirmation of single or multiple types.For example, can define one confirms and an affirmation based on distribution fast.Affirmation can be used for only confirming that RACH PDU has been access in a reception fast, and does not distribute the FCH/RCH resource to user terminal.Comprise distribution for FCH and/or the RCH of current tdd frame based on the affirmation that distributes.
FCCH can otherwise realize, also can be sent out in every way.In one embodiment, FCCH is sent out with the single speed that transmits in BCH message.All users' that this speed can be sent in current tdd frame based on for example FCCH lowest signal is selected than (SNR) Noise and Interference.According to the channel adjustment of receiver's user terminal in each tdd frame, can use different speed for different tdd frames.
In another embodiment, FCCH realizes with a plurality of (for example four) FCCH subchannel.Each FCCH subchannel is sent out with a different speed, and the required SNR different from is relevant, in order to recover subchannel.The FCCH subchannel is sent out with the order of minimum speed limit to flank speed.Each FCCH subchannel may or may in given tdd frame, not be sent out.The one FCCH subchannel (having minimum speed limit) at first is sent out, and can be received by all user terminals.Whether this FCCH channel can show can send each remaining FCCH subchannel in current tdd frame.Each user terminal can be processed the FCCH subchannel that sends and obtain its FCCH information element.Each user terminal can when following any point occurs the processing of termination FCCH: (1) fails the FCCH subchannel of decoding current, (2) in current FCCH channel, receive its FCCH information element, or the FCCH subchannel of (3) all transmissions is all processed.Decode and unsuccessfully just can stop the processing of FCCH as long as user terminal runs into FCCH, because the FCCH subchannel is sent out with the speed that rises, user terminal can not can be decoded with the follow-up FCCH subchannel of higher rate transmission.
3. direct access communications channels (RACH)-up link
User terminal obtains to send SMS message to the access of system and to access point with RACH.The operation of RACH is based on the Aloha arbitrary access agreement of time-division slot, and this is described below.
Fig. 5 C has illustrated the embodiment of RACH PDU 450.In this embodiment, RACH PDU comprises leader part 552 and message part 554.If user terminal has many antennas, then leader part 552 can be used for sending a controlled benchmark.The pilot tone that controlled benchmark is comprised of one group of special modulated symbol, it was subjected to spatial manipulation before up link sends.Spatial manipulation makes pilot tone be sent out in a specific eigenmodes of mimo channel.The below has been described in further detail the processing of controlled benchmark.Leader part 552 has the fixedly duration of at least 2 OFDM code elements.Message part 554 transmits a RACH message, and has the variable duration.Therefore the duration of RACH PDU is variable.
In one embodiment, support four different speed for RACH.The employed special speed of each RACH message is represented by the RACH data rate indicator (DRI) of one 2 bits.In one embodiment, also support four different message sizes for RACH.The size of each RACH message is represented by the message part field that is included in the RACH message.Each support 1,2,3 of RACH speed or whole 4 message sizes.Table 15 is listed the message size that four RACH speed, their relevant codings and modulation parameter and these RACH speed are supported.
Table 15
RACH message sends from the short message of user's terminal and access request.Table 16 is listed each each field size of each field of an exemplary RACH message and four different messages sizes.
Table 16
Message duration field list understands the size of RACH message.MAC PDU type field shows the RACH type of message.The MAC id field comprises the MAC ID that the energy unique identification sends the user terminal of RACH message.Between the starter system access periods, unique MAC ID is not assigned to user terminal.In this situation, can in the MAC id field, comprise a registration MAC ID (particular value that for example keeps for the registration purpose).The time slot id field represents the RACH time slot that begins, sends RACH PDU (RACH being described below regularly and transmission) on it.The pay(useful) load field comprises the information bit of RACH message.Crc field comprises the crc value of RACH message, tail bit field be used for the resetting convolution coder of RACH.The below is described in further detail the operation of RACH and BCH and the FCCH that is used for system access.
RACH also can realize with " fast " RACH (F-RACH) and " slowly " RACH (S-RACH).F-RACH and S-RACH can be designed to effectively support user terminal under the different operating state.For example, F-RACH can be used by user terminal: (1) is to system registry, (2) regularly compensate their round-trip delay (RTD) by correctly in advance their transmission, and (3) realize required SNR for the operation on the F-RACH.S-RACH can be used the user terminal of F-RACH to use in no instance.
Can for F-RACH and S-RACH use different designs so that whenever may be just connecting system rapidly, and make and realize that the required amount of arbitrary access is minimum.For example, F-RACH can use shorter PDU, adopts weak encoding scheme, requires F-RACH PDU time proximity to arrive alignedly the access point place, and uses the Aloha random access scheme of time-division slot.S-RACH can use long PDU, adopts stronger encoding scheme, allows S-RACH PDU to arrive access point in non-alignment ground in time, and uses the not Aloha random access scheme of time-division slot.
For simplicity, below description is assumed to the MIMO wlan system and uses single RACH.
4. forward channel (FCH)-down link
Access point uses FCH that customer-specific data is sent to specific user terminal, and paging/broadcast is sent to a plurality of user terminals.FCH can frame by frame be assigned with.Provide a plurality of FCH PDU types to adapt to the different purposes of FCH.Table 17 is listed one group of exemplary FCH PDU type.
Table 17-FCH PDU type
Fig. 5 D has illustrated the embodiment of the FCH PDU 430a of FCH PDU type 0.In this embodiment, FCH PDU 430a only comprises a message part 534a of paging/broadcast or user grouping.Message/packet can have variable length, and this length is provided by the FCH message length field among the FCH PDU.Message-length provides (the following describes) with an integer PHY frame.The below specifies and has described speed and the transmission mode of paging/broadcast.Speed and the transmission mode of user grouping in relevant FCCH information element, have been specified.
Fig. 5 E has illustrated the embodiment of the FCH PDU 430b of FCH PDU Class1.In this embodiment, FCH PDU 430b comprises a leader part 532b and a message/packet part 534b.Leader part 532b is used for sending MIMO pilot tone or controlled benchmark, and has variable length, and variable-length is provided by the FCH leader type field in the relevant FCCH information element.Part 534b is used for sending the FCH grouping, and also has variable length (representing with an integer PHY frame), and variable-length is provided by the FCH message length field among the FCH PDU.The FCH grouping sends with speed and the transmission mode of relevant FCCH information element appointment.
Fig. 5 F has illustrated the embodiment of the FCH PDU 430c of FCH PDU type 2.In this embodiment, FCH PDU 430c only comprises leader part 532c, and does not comprise message part.The length of leader part is indicated by FCCH IE.FCH PDU type 2 can be used to make user terminal can upgrade its channel estimating in idle condition lower time.
Provide a plurality of FCH type of messages to adapt to the different purposes of FCH.Table 18 has been listed one group of exemplary FCH type of message.
Table 18-FCH type of message
A beep-page message can be used for a plurality of user terminals of paging, and sends with FCH PDU type 0.If be provided with the paging bit in the BCH message, then at first send the one or more FCH PDU (i.e. " paging PDU ") with pilot tone message at FCH.In same frame, can send a plurality of paging PDU.The minimum speed limit of diversity mode and 0.25bps/Hz is used in the transmission of paging PDU, in order to improve the correct probability that receives of user terminal.
One broadcast can be used to information is sent to a plurality of user terminals, and sends with FCH PDU type 0.If be provided with the broadcasting bit in the BCH message, after any paging PDU that then and then FCH upward sends, at the one or more FCH PDUs (i.e. " broadcasting PDU ") of FCH transmission with broadcast.The minimum speed limit of diversity mode and 0.25bps/Hz is also used in the transmission of broadcasting PDU, in order to improve the correct probability that receives.
One user grouping can be used to send customer-specific data, and can send with FCH PDU Class1 or 2.After FCH sent any paging and broadcasting PDU, Class1 and 2 user PDU were sent out at FCH.Each user PDU can send with diversity, wave beam control or space multiplexing mode.The FCCH information element has been specified the employed speed of each user PDU and the transmission mode that sends at FCH.
The message of the upper transmission of FCH or grouping comprise an integer PHY frame.In one embodiment, as described below, each PHY frame can comprise a crc value, and this value is so that can check and retransmit independent PHY frame among the FCH PDU in necessary formula.For asynchronous service, can adopt RLP that the PHY frame in the given FCH PDU is carried out segmentation, retransmits and ressembles.In another embodiment, provide a crc value for each message or grouping rather than for each PHY frame.
Fig. 6 has illustrated an embodiment of the structure of FCH grouping 534.The FCH grouping comprises an integer PHY frame 610.Each PHY frame 610 comprises pay(useful) load field 622, crc field 624 and tail bit field 626.The one PHY frame of FCH grouping also comprises header fields 620, its expression type of message and duration.Last PHY frame in the FCH grouping also comprises filling bit field 628, and this field 628 comprises the null filling bit in ending place of pay(useful) load, in order to fill last PHY frame.In one embodiment, each PHY frame comprises 6 OFDM code elements.The bit number that comprises in each PHY frame depends on the employed speed of this PHY frame.
Table 19 is listed each field of the exemplary FCH PDU form of FCH PDU type 0 and 1.
Table 19-FCH PDU form
FCH type of message and FCH message length field are sent out in the header of the PHY frame of FCH PDU.Pay(useful) load, CRC and tail bit field are included in each PHY frame.The pay(useful) load of each FCH PDU partly transmits the information bit of paging/broadcast or user's packet dedicated.Filling bit is used for filling as required last PHY frame of FCH PDU.
Also can define the OFDM code element that the PHY frame comprises some other quantity (for example 1,2,4,8 etc.).Owing to being to send in pairs for diversity mode OFDM code element, so the PHY frame can define with even number OFDM code element, and diversity mode can be used for FCH and RCH.The PHY frame size can be selected based on the traffic of expection, and nullified property is minimum.Particularly, if frame size is excessive, then produce ineffectivity by sending low volume data with a large PHY frame.Perhaps, if frame size is too small, then expense has represented the most of frame.
5. backward channel (RCH)-up link
User terminal uses RCH that uplink data and pilot tone are sent to access point.RCH can be assigned with according to each tdd frame.Can specify one or more user terminals in arbitrary given tdd frame, to send at RCH.Provide multiple RCH PDU type to adapt to different working modes on the RCH.Table 20 has been listed one group of exemplary RCH PDU type.
Table 20-RCH PDU type
Fig. 5 D has illustrated the embodiment of the RCH PDU of RCH PDU type 0.In this embodiment, RCH PDU only comprises the message part 534a of variable-length RCH grouping, and this grouping is provided with an integer PHY frame by the RCH message length field among the RCH PDU.The speed of RCH grouping is specified in relevant FCCH information element with transmission mode.
Fig. 5 E has illustrated the embodiment of the RCH PDU of RCH PDUY Class1.In this embodiment, RCH PDU comprises leader part 532b and grouping part 534b.Leader part 532b is used for sending a benchmark (for example MIMO pilot tone or controlled benchmark), and has variable length, and described length is provided by the RCH leader type field in the relevant FCCH information element.Part 534b is used for sending RCH grouping, and has variable length, and described variable-length is provided by the RCH message length field among the RCH PDU.The RCH grouping sends with speed and the transmission mode of appointment in the relevant FCCH information element.
Fig. 5 G has illustrated the embodiment of the RCH PDU 350d of RCH PDU type 2.In this embodiment, RCH PDU comprises leader part 532d and message part 535d.Leader part 532d is used for sending a benchmark, and length is 1,4 or 8 OFDM code element.Part 536d is used for sending a short RCH message, and has the regular length of an OFDM code element.Short RCH message sends (for example speed 1/2 or speed 1/4 and BPSK modulation) with specific speed and transmission mode.
The grouping of the upper transmission of RCH (for PDU type 0 and 1) comprises an integer PHY frame.Fig. 6 illustrates the structure of RCH grouping (for PDU type 0 and 1, for the FCH grouping equally so.The RCH grouping comprises an integer PHY frame 610.Each PHY frame comprises pay(useful) load field 622, crc field 624 and the tail bit field 626 chosen wantonly.PHY frame in the RCH grouping also comprises header part 620, and last the PHY frame in the grouping also comprises filling bit field 628.
Table 21 is listed each field of the exemplary RCH PDU form of RCH PDU type 0 and 1.
Table 21-RCH PDU form (PDU type 0 and 1)
RCH type of message, RCH message-length and FCH rate indicator field are sent out in the header of the PHY frame of RCH PDU.FCH rate indicator field is used for a FCH rate information (for example each space channel support maximum rate) and is sent to access point.
Table 22 has been listed each field of the exemplary RCH PDU form of RCH PDU type 2.
The RCH message of table 22-RCH PDU type 2
User terminal is asked additional capacity on the up link with the RCH request field.This short RCH message does not comprise CRC, and is sent out in single OFDM code element.
6. dedicated channel activity
Transfer of data on RCH and the RCH can occur independently.According to use the transmission mode of selecting for RCH and RCH, one or more space channels (for wave beam control and diversity mode) can be movable, and for the transfer of data of each dedicated transmission channel.Each space channel can be associated with a specific speed.
As FCH only or when only whole four speed of RCH are set as zero, user terminal is idle at this link.Non-occupied terminal still can send an idle PDU at RCH.When whole four speed of FCH and RCH all were set as zero, access point and user terminal were all closed and are not sent.The user terminal that is less than four transmit antennas is made as zero to obsolete speed field.User terminal more than four transmit antennas sends data with being no more than four space channels.Transmission rate and channel activity when table 23 is illustrated in speed on whole four space channels of one of FCH or RCH (or both) and is set as zero.
Table 23
RCH and FCH idle (namely not sending data) but still send the situation of leader may be arranged.This is called idle condition.As shown in table 13, the control field that is used for supporting the user terminal under the idle condition is provided in FCCH IE type 2 information elements.
7. other design
For simplicity, for exemplary design specific PDU type, PDU structure, message format etc. have been described.Also can define and use less, additional and/or different type, structure and forms, this within the scope of the invention.
The III.OFDM sub band structure
In the foregoing description, use identical OFDM sub band structure for whole transmission channels.By using different OFDM sub band structure can realize improved efficient for different transmission channels.For example, can use 64 sub band structure for some transmission channels, can use for some other transmission channels the structure of 256 subbands, etc.In addition, can use a plurality of OFDM sub band structure for a given transmission channel.
For given system bandwidth W, the duration of OFDM code element is depended on sub-band sum.If sub-band sum is N, then each is N/W microsecond (if the unit of W is WHz) through the duration of conversion code element (not having Cyclic Prefix).Add a Cyclic Prefix to each through the code element of conversion and form corresponding OFDM code element.The length of Cyclic Prefix is determined by the desired delay spread of system.Cyclic Prefix represents expense, and expense is the expense that each OFDM code element needs for the contrary frequency selective channel.If code element is very short, this expense represents the OFDM code element of larger percentage, if code element is very long, this expense is the OFDM code element of the less percentage of expression just.
Because different transmission channels can be associated with dissimilar traffic data, therefore can select a suitable OFDM sub band structure to be used for each transmission channel so that with the traffic data type matching of expection.If expection has mass data to send at given transmission channel, then can define larger sub band structure and be used for this transmission channel.In this situation, Cyclic Prefix can represent the OFDM code element of less percentage and realize larger efficient.On the contrary, if will send low volume data in a given transmission channel expection, then can define less sub band structure and be used for this transmission channel.In this situation, even Cyclic Prefix has represented the larger percentage of OFDM code element, by reduce the quantity of excessive capacity with less OFDM code element size, still can realize higher efficient.Therefore, the OFDM code element can be regarded as one " boxcar (boxcar) ", can select according to the data volume that expection will send " boxcar " of just size for each transmission channel.
For example, for the above embodiments, the data on FCH and the RCH are sent out in the PHY frame, and each PHY frame all is comprised of 6 OFDM code elements.In this situation, can define another OFDM structure to be used for FCH and RCH.For example, can define for FCH and RCH the structure of 256 subbands." greatly " OFDM code element of 256 sub band structure can be approximate four times of 64 sub band structure " little " OFDM code element on the duration, but also can be four times on data transmission capacity.Yet, only need a Cyclic Prefix for a large OFDM code element, and need four Cyclic Prefix for four little OFDM code elements of equivalence.Like this, by using 256 larger sub band structure can reduce by 75% cyclic redundancy expense number.
This concept can be expanded, thereby can use different OFDM sub band structure for same transmission channel.For example, RCH supports different PDU types, each type and a specific Size dependence connection.In this situation, can use larger sub band structure for the RCH PDU type of large-size, and can use less sub band structure for the RCHPDU type of reduced size.Also can use for given PDU the combination of different sub-band structure.For example, if a long OFDM code element is equivalent to four short (OFDM) code elements, then can use N
LargeIndividual large OFDM code element and N
SmallIndividual little OFDM code element sends PDU, wherein N
Large〉=0 and 3 〉=N
Small〉=0.
Different OFDM sub band structure is associated with the OFDM code element of different length.Like this, if be that different transmission channel (and/be same transmission channel) uses different OFDM sub band structure, then the FCH of FCH and RCHPDU and RCH skew meeting need to be specified with correct temporal resolution, and this temporal resolution is less than an OFDM code-element period.Particularly, the incremental time of FCH and RCH PDU can provide with an integer circulating prefix-length, rather than the OFDM code-element period.
IV. speed and transmission mode
Above-mentioned transmission channel is used for being various services and function transmission Various types of data.Each transmission channel can be designed to support one or more speed and one or more transmission mode.
1. transmission mode
For transmission channel is supported multiple transmission mode.As described below, each transmission mode is processed with the particular space at transmitter and receiver place and is associated.Table 24 is listed the transmission mode that each transmission channel is supported.
Table 24
For diversity mode, for implementation space, frequency and/or time diversity, each data symbols sends in many transmit antennas, a plurality of subband, a plurality of code-element period or their combination redundantly.For the wave beam control model, single space channel is used for transfer of data (generally being best space channel), each data symbols with transmitting antenna can with full transmitted power be sent out at single space channel.For space multiplexing mode, a plurality of space channels are used for transfer of data, and each data symbols is sent out at a space channel, and wherein a space channel is corresponding to an eigenmodes, a transmitting antenna etc.The wave beam control model can be regarded as the special circumstances of space multiplexing mode, wherein only carries out transfer of data with a space channel.
Diversity mode can be used for the Common transport channel (BCH and FCCH) of the down link from the access point to the user terminal.Diversity mode also can be used for dedicated transmission channel (FCH and RCH).Diversity mode is consulted when the use on FCH and the RCH can be in call setup.Diversity mode uses a pair of antenna to send data one " spatial model " for each subband.
The wave beam control model can be adopted by the user terminal with many transmit antennas on RACH.User terminal can be estimated mimo channel based on the upper MIMO pilot tone that sends of BCH.Then this channel estimating is used for carrying out wave beam control for system access on RACH.The wave beam control model also can be used for dedicated transmission channel (FCH and RCH).By utilizing the gain of transmitter place antenna array, the wave beam control model perhaps can be at the receiver place than diversity mode realize higher signal to Noise and Interference than (SNR).In addition, because controlled benchmark only comprises the code element of single " controlled " antenna, so the leader of PDU part can reduce.Diversity mode also can be used for RACH.
When channel condition was supported, space multiplexing mode can be used for FCH and RCH realizes higher throughput.Space multiplexing mode and wave beam control model are that benchmark drives, and to correct operation requirements closed-loop control.Like this, user terminal all is assigned to resource with the support space multiplexer mode on FCH and RCH.On FCH and RCH, can support nearly four space channels (being subject to access point place antenna amount limits).
2. coding and modulation
For transmission channel is supported a plurality of different speed.Each speed is associated with a specific code rate and a specific modulation scheme, and both are in conjunction with producing a specific frequency spectrum efficient (or data rate) afterwards.Table 25 is listed each speed that system supports.
Table 25
Each Common transport channel is supported one or more speed and transmission mode (or may be a plurality of, such as the situation of RACH).BCH uses diversity mode to be sent out with fixed rate.Use diversity mode, FCCH can be sent out with one of four possible speed, and is represented such as the FCCH multiplicative model field in the BCH message.In one embodiment, RACH can be sent out with one of four possible speed, and the RACH DRI that embeds in the leader such as RACH PDU is indicated, and each RACH message is one of four possible sizes.In another embodiment, RACH is sent out with single speed.Table 26 is listed coding, modulation and transformation parameter and the message size that each Common transport channel is supported.
The parameter of table 26-Common transport channel
The size of FCCH message is variable, and provides with even number OFDM code element.
Whole speed of listing in FCH and the RCH support matrix 25.Table 27 is listed coding, modulation and transformation parameter and the message size that FCH and RCH support.
The parameter of table 27-FCH and RCH
Annotate A: repeat at two subbands in each speed 1/2, in order to obtain efficient coding speed 1/4.The redundant bit that the parity bits presentation code is introduced, and be used for the error correction of receiver.
PHY frame size in the table 27 represents the number of coded-bit, modulated symbol and the OFDM code element of each PHY frame.If transfer of data has been used 48 data subbands, then each OFDM code element comprises 48 modulated symbols.For diversity and wave beam control model, send a code element stream, and the single speed that adopts corresponding to this code element stream of PHY frame size.For space multiplexing mode, a plurality of code element stream can be sent out at a plurality of space channels, and total PHY frame size can be determined by the PHY frame size sum of independent space channel.The PHY frame size of each space channel is determined by the speed that this space channel adopts.
For example, suppose mimo channel can be supported in 0.5,1.5,4.5 and the spectrum efficiency of 5.5bps/Hz under four spatial sub-channels of working.So shown in the table 28 be four speed that four space channels are selected.
Table 28-instance space multiplexing transmission
So total PHY frame size is 144+432+1296+1584 information bit or 288+576+1728+2304 coded-bit.Even each of four space channels is supported the pay(useful) load bit of varying number, Zong the PHY frame also can be sent out (for example 24 microseconds are supposed 4 microseconds/OFDM code element) in 6 OFDM code elements.
V. physical layer process
Fig. 7 illustrates access point 110x in the MIMO wlan system and the block diagram of two user terminal 120x and 120y one embodiment.
On down link, at access point 110x place, send (TX) data processor 710 and receive from the traffic data (being information bit) of data source 708 and come self-controller 730 and signaling and the out of Memory of possible scheduler 734.This Various types of data can be sent out at different transmission channels.Send 710 pairs of data of data processor carry out " framing " (if necessary), to framing/data of separating frame upset, to encode through the data that upset, to encoded data interweave (i.e. rearrangement) and the data-mapping through interweaving to modulated symbol.For simplicity, " data symbols " refers to the modulated symbol of traffic data, and " pilot frequency code element " refers to the modulated symbol of pilot tone.Upset is the data bit randomization.Coding has improved the reliability of transfer of data.Interweaving provides time, frequency and/or space diversity for the bit of having encoded.Upset, encode and modulate and can carry out based on the control signal that controller 730 provides, the below is described in further detail.Send data processor 710 and provide a modulation, symbol streams for employed each space channel of transfer of data.
Send spatial processor 720 and receive one or more modulation, symbol streams from sending data processor 710, and modulated symbol is carried out spatial manipulation in order to four transmitter code flow filaments are provided, for every transmit antennas a stream is arranged.The below has been described in further detail spatial manipulation.
Each modulator (MOD) 722 receives and processes a corresponding transmitter code flow filament in order to a corresponding OFDM code element stream is provided.Each OFDM code element stream is further processed, in order to a corresponding down link modulated signal is provided.Then send respectively automodulation device 722a from four antenna 724a to 724d to four down link modulated signals of 722d.
At each user terminal 120 place, one or more antenna 752 receives the down link modulated signal that sends, and every reception antenna all provides one to receive signal to corresponding demodulator (DEMOD) 754.Each demodulator 754 is carried out the opposite processing of processing of carrying out with modulator 722 places, and receiving symbol is provided.Then, receive 720 pairs of receiving symbols from all demodulators 754 of (RX) spatial processor and carry out spatial manipulation so that the code element through recovering to be provided, the code element through recovering is the estimation of the modulated symbol that sends of access point.
Receive data processor 770 receives through the code element of recovery and with its multichannel and decomposes in their corresponding transmission channels.The code element through recovering of each transmission channel can be conciliate through symbol de-maps, deinterleaving, decoding and be upset, in order to provide data through decoding for this transmission channel.Each transmission channel can comprise grouped data through recovering, message, signaling etc. through decoded data, the latter is provided for data sink 722 and preserves, and/or is provided for controller 780 and is further processed.
The below has been described in further detail the access point 110 of down link and the processing of terminal 120.The processing of up link can be identical or different with the processing of down link.
For down link, at each active user terminals 120 place, receive spatial processor 760 further estimating down-ward links to obtain channel condition information (CSI).CSI can comprise SNR that channel response is estimated, received etc.Receive data processor 770 can also provide the state of each packet/frame that receives on the down link.Controller 780 receiving channel state informations and packet/frame state, and definite feedback information that will be sent back to access point.Feedback information is processed by sending data processor 790 and sending spatial processor 792 (if existence), is regulated by one or more modulators 754, and is sent back to access point via one or more antenna 752.
At access point 110 places, the uplink signal that sends by antenna 724 receive, by demodulator 722 demodulation, and process in the opposite mode of mode of carrying out with the user terminal place by receiving spatial processor 740 and receive data processor 742.Then the feedback information through recovering is offered controller 730 and scheduler 734.
Support multiple transmission mode for the transfer of data on down link and the up link.The below is described in further detail each processing of these transmission modes.
1. diversity mode-transmission processing
Fig. 8 A illustrates the block diagram that can carry out for diversity mode transmitter unit 800 1 embodiment of transmission processing.Transmitter 800 can be used for the transmitter part of access point and user terminal.
In sending data processor 710a, the data of each grouping that 808 pairs of framing unit will send at FCH or RCH are carried out framing.Framing need not to carry out for other transmission channel.Framing can be carried out as shown in Figure 6, in order to generate one or more PHY frames for each user grouping.Then, disarrangement device 810 data for the framing of each transmission channel/solution frame upset, in order to make the data randomization.
Then, interleaver 818 based on selected interleaving scheme to the coded-bit from unit 814 interweave (i.e. rearrangement).In one embodiment, reportedly send subband (or referred to as data subband) expansion in 48 numbers at every group of 48 continuous programming code bits that a given space channel sends, in order to frequency diversity is provided.The below has been described in further detail interleaving process.
Symbol mapped unit 820 then shines upon data through interweaving so that modulated symbol to be provided according to a specific modulation scheme.Shown in table 26, according to selected speed, diversity mode can use BPSK, 4QAM or 16QAM.In diversity mode, for all data subbands use same modulation scheme.Symbol mapped can be by following realization: each group of (1) tissue B bit to be to form the B bit value, B 〉=1 wherein, and (2) each B bit value be mapped in the signal group of stars corresponding with the selected modulation scheme a bit.Each mapped signaling point is a complex values, and corresponding to a modulated symbol.Symbol mapped unit 820 provides a modulation, symbol streams to sending diversity processor 720a.
In one embodiment, diversity mode is that two diversity that send are used space time transmit diversity (STTD) according to each subband.STTD supports to transmit when independently code element stream is on two transmit antennas, and keeps simultaneously the orthogonality at receiver place.
The following running of STTD scheme.Suppose and to send two modulated symbols at a given subband, be labeled as s
1And s
2Transmitter generates two vectors:
x 1=[s
1s
2]
TWith
Wherein " * " represents complex conjugate, and " T " represents transposition.Each vector is included in the code-element period two element (that is, vectors that will send from two transmit antennas
x 1In the first code-element period, send vector from two antennas
x 2In next code-element period, send from two antennas).
If receiver is equipped with single reception antenna, then receiving symbol can be expressed as:
r
1＝h
1s
1+h
2s
2+n
1， (1)
R wherein
1And r
2That receiver is in two code elements that receive in two continuous code-element periods;
h
1And h
2Be for the path gain of subband from two transmit antennas to reception antenna in considering, suppose that wherein path gain is constant on this subband, and keep static in the cycle of 2 code elements; And
n
1And n
2Be respectively with two receiving symbol r
1And r
2The noise that is associated.
Receiver then can two transmit symbol s of following derivation
1And s
2Estimation:
Perhaps, transmitter can generate two vectors
With
And in two code-element periods, sequentially send this two vectors from two transmit antennas.So receiving symbol can be expressed as:
Receiver is followed the estimation of two transmit symbol of following derivation:
Foregoing description can be expanded be used to two or many transmit antennas, N are arranged
RThe MIMO-OFDM system of root reception antenna and a plurality of subbands.Two transmit antennas have been used for arbitrary given subband.Suppose on a given subband k to send two modulated symbols, be labeled as s
1(k) and s
2(k).Transmitter generates two vectors
x 1=[s
1(k) s
2(k)]
TWith
Perhaps two of equal value code-element sets
With
Each code-element set is included in upper two elements that sequentially send from corresponding transmitting antenna of subband k in two code-element periods (be code-element set { x
i(k) } in two code-element periods, sending code-element set { x on the subband k from antenna i
j(k) } in 2 same code-element periods, sending from antenna j on the subband k).
The vector of the receiving symbol at two interior reception antenna places of code-element period can be expressed as:
r 1(k)＝
h i(k)s
1(k)+
h j(k)s
2(k)+
n 1(k)，
Wherein
r 1(k) and
r 2(k) be the symbol vector that receives at the receiver place in two continuous code-element periods on the subband k, each vector comprises N
RThe N of root reception antenna
RIndividual receiving symbol;
h i(k) and
h j(k) be from two transmit antennas i and j to N for subband k
RThe vector of the path gain of root reception antenna, each vector comprise from relevant transmitting antenna to N
RThe channel gain of each root of root reception antenna supposes that wherein path gain is constant and static in the maintenance of 2 code-element periods on this subband; And
n 1(k) and
n 2(k) be to receive vector with two respectively
r 1(k) and
r 2(k) noise vector that is associated.
Then, receiver can two transmit symbol s of following derivation
1(k) and s
2(k) estimation:
Perhaps, transmitter can generate two code-element set { x
i(k) }={ s
1(k) s
2(k) } and
And send this two code-element sets from two transmit antennas i and j.So the vector of receiving symbol can be expressed as:
Then, the estimation that receiver can two transmit symbol of following derivation:
The STTD scheme is described in the paper that is entitled as " A Simple Transmit Diversity Technique forWireless Communications " by S.M.Alamouti, this paper publishing is on the IEEE periodical in the selected field of relevant communication, in October, 1998 No. 8 the 16th volume, the 1451-1458 page or leaf.The STTD scheme is also described in the U.S. Patent application of following common transfer: in the 09/737th of submission on January 5 calendar year 2001, No. 602 applications are entitled as " Method and System for Increased Bandwidth Efficiency in Multiple Input-Multiple Output Channels "; And in the 10/179th, No. 439 application that on June 24th, 2002 submitted to, be entitled as " Diversity Transmission Modes for MIMO OFDM Communication Systems ".
The STTD scheme sends a modulated symbol by two transmit antennas in each subband in each code-element period.Yet, the distributed intelligence in each modulated symbol on two continuous OFDM code elements of STTD scheme.Like this, the symbol recovery at receiver place is carried out based on two OFDM code elements that receive continuously.
The STTD scheme is used a pair of transmitting antenna for each data subband.Because access point comprises four transmit antennas, therefore can select every antenna to be used for half of 48 data subbands.Table 29 is listed the exemplary subband of STTD scheme-antenna assignment scheme.
Table 29
Shown in table 29, it be-26 ,-19 ,-13 etc. subband that transmitting antenna 1 and 2 is used for index, and it is-25 ,-18 ,-12 etc. subband that transmitting antenna 2 and 4 is used for index, and transmitting antenna 1 and 3 is-24 ,-17 ,-11 etc. subband for index, and the rest may be inferred.Four transmit antennas has six different antennas pair.Two right each of antenna are used for 8 data subbands, and 8 data subbands are at the approximate equably interval of 48 data subbands.Antenna is to the distribution of subband so that be the different antenna of adjacent sub-bands use, and this can provide larger frequency and space diversity.For example, antenna 1 and 2 is used for subband-26, and antenna 3 and 4 is used for subband-25.
Antenna-allocation of subbands in the table 29 is also so that be that each coded-bit of minimum speed limit 1/4 uses whole four transmit antennas, and this makes antenna diversity maximum.For speed 1/4, each coded-bit is repeated and sends (being also referred to as Shuangzi band repeated encoding) at two subbands.Two used subbands of each coded-bit are mapped to different antenna pair, so that send this coded-bit with four whole antennas.For example, the bit index 0 in the table 29 and 1 is corresponding to the same coded-bit under the diversity mode, and wherein index is that 0 bit sends from antenna 1 and 2 on subband-26, and index is that 1 bit sends from antenna 3 and 4 on subband 1.For another example, the bit index 2 in the table 29 and 3 is corresponding to same coded-bit, and wherein index is that 2 bit sends from antenna 1 and 3 on subband-17, and index is that 3 bit sends from antenna 2 and 4 on subband 10.
System can support other to send diversity scheme, and this within the scope of the invention.For example, system can support a space-frequency to send diversity (SFTD), and it can be according to each subband to coming implementation space and frequency diversity.The one exemplary following running of SFTD scheme.Suppose to generate two modulated symbol s (k) and s (k+1), and they are mapped to two adjacent sub-bands of OFDM code element.For SFTD, launching opportunity is sent code element s (k) and s (k+1) from two antennas on subband k, and can send code element s from two identical antennas on subband k+1
*(k+1) and-s
*(k).Because the supposition channel response keeps constant for two right transmissions of code element, so modulated symbol is to having used adjacent subband.It is identical with the processing of STTD scheme that the processing of modulated symbol be used for is recovered at the receiver place, except the receiving symbol of the receiving symbol of processing two subbands rather than two OFDM code-element periods.
Fig. 8 B illustrates the block diagram of an embodiment of the transmission diversity processor 720a of the STTD scheme that can realize under the diversity mode.
In sending diversity processor 720a, demultiplexer 832 receives modulation, symbol streams s (n) from sending data processor 710a, and its multichannel is resolved into 48 subflows for 48 data subbands, is labeled as s
1(n) to s
1(n).Each modulated symbol subflow comprises a modulated symbol for a code-element period, corresponding to chip rate (T
OFDM)
-1, T wherein
OFDMIt is the duration of an OFDM code element.Each modulation, symbol streams is provided for corresponding transmission subband diversity processor 840.
In each sent subband diversity processor 840, demultiplexer 842 resolved into two sequence of symhols to the modulated symbol multichannel of this subband, and the chip rate of each sequence is (2T
OFDM)
-1Space Time Coding device 850 receives these two modulated symbol sequences, and for each 2 code-element period, uses two code element s in these two sequences
1And s
2Be that two transmit antennas form two code-element sets
With
Each code-element set comprises two code elements, and each code element is from one of two sequences.By code element s at first is provided
1Next provides code element s
2 *And generated code metaset { x
i, wherein obtain s by switch 856a
1, by getting s with unit 852a
2Conjugation and with delay cell 854a code-element period of symbol delay of conjugation is obtained s
2 *Shown in table 29, two code-element set { x
iAnd { x
jWill send from two antenna i and the j that distributes to subband.Space Time Coding device 850 for the first transmit antennas i the first code-element set
Offer buffer/multiplexer 870, for the second transmit antennas j the second code metaset
Offer another buffer/multiplexer 870.Controlled encoder 850 is called as the STTD code element for two code elements that each code-element period provides.
Buffer/multiplexer 870a is used for the STTD code element from all diversity processors 840 is cushioned with multiplexed to 870d.According to determining of table 29, each buffer/multiplexer 870 receives pilot frequency code element and STTD code element from suitable transmission subband diversity processor 840.For example, buffer/multiplexer 870a receives subband-26,-24,-22, the modulated symbol of-19 etc. (namely being mapped to all subbands of antenna 1), buffer/multiplexer 870b receives subband-26,-23,-20, the modulated symbol of-19 etc. (namely being mapped to all subbands of antenna 2), buffer/multiplexer 870c receives subband-25,-24,-20, the modulated symbol of-18 etc. (namely being mapped to all subbands of antenna 3), buffer/multiplexer 870d receives subband-25,-23,-22, the modulated symbol of-18 etc. (namely being mapped to all subbands of antenna 4).
Then for each code-element period, each buffer/multiplexer 870 is respectively four pilot subbands, 24 data subbands and 36 and does not use multiplexed four pilot tones of subband, 24 STTD code elements and 36 zero, in order to be the sequence that 64 total subbands form one 64 transmit symbol.Although always have 48 data subbands, for diversity mode, only used 24 subbands for every transmit antennas, therefore, it is 36 rather than 12 that every antenna does not use the substantial amt of subband.Each transmit symbol is the complex values (can be zero for untapped subband) that sends at a subband in a code-element period.Each buffer/multiplexer 870 provides a transmitter code flow filament x for a transmit antennas
i(n).Each transmitter code flow filament comprises the modular cascade sequence of 64 transmit symbol, and a code-element period has a sequence.Refer back to Fig. 8 A, send diversity processor 720a four transmitter code flow filament x are provided to four OFDM modulator 722a to 722d
1(n) to x
4(n).
Fig. 8 C illustrates the block diagram of OFDM modulator 722x one embodiment, and this modulator can be used for each OFDM modulator 722a among Fig. 8 A to 722d.In OFDM modulator 722x, invert fast fourier transformation (IFFT) unit 852 receives a transmitter code flow filament x
iAnd use one 64 invert fast fourier transformation that the sequence of each 64 transmit symbol is converted to its time-domain representation (calling the code element through conversion) (n).Each code element through conversion comprises corresponding to 64 time-domain samplings of 64 subbands altogether.
For each code element through conversion, Cyclic Prefix maker 854 repeat a part through the conversion code element to form corresponding OFDM code element.As mentioned above, can use one of two different circulating prefix-lengths.The Cyclic Prefix of BCH is fixed, and is 800nsec.The Cyclic Prefix of all other transmission channels all is optional (or 400nsec or 800nsec), and is represented by the Cyclic Prefix duration field of BCH message.Be that 20MHz, sampling period are the system of 50nsec and 64 fields for bandwidth, each is 3.2 milliseconds (namely 64 * 50nsec) through the duration of conversion code element, duration of each OFDM code element or be 3.6 milliseconds or be 4.0 milliseconds, what this depended on that the OFDM code element uses is 400nsec or the Cyclic Prefix of 800nsec.
Fig. 8 D has illustrated an OFDM code element.The OFDM code element is comprised of two parts: the duration be 400 or the Cyclic Prefix (8 or 16 samplings) of 800nsec and duration be 3.2 microseconds through conversion code element (64 samplings).Cyclic Prefix is through the copy of last 8 or 16 samplings of conversion code element (being circulation continuous), and is inserted in the front through the conversion code element.Cyclic Prefix quebaoOFDM1 code element can keep its orthogonality when having the multidiameter expansion, thereby has improved the performance of the harmful path effects of antagonism, and described ill-effect is such as the multipath that is caused by frequency selective fading and channel diffusion.
Cyclic Prefix maker 854 provides an OFDM code element stream to transmitter (TMTR) 856.Transmitter 856 is converted to one or more analog signals to the OFDM code element stream, and to further amplification of analog signal, filtering and up-conversion, is convenient to send from relevant antenna in order to generate a modulated signal.
The baseband waveform of OFDM code element can be expressed as:
Wherein n represents code-element period (being the OFDM symbol index);
K represents subband index;
N
STIt is the number of pilot tone and data subband;
c
n(k) be illustrated in the code element that sends on the subband k of code-element period n; And
T wherein
CPIt is the Cyclic Prefix duration;
T
SIt is the OFDM code element duration; And
Δ f is the bandwidth of each subband.
2. space multiplexing mode-transmission processing
Fig. 9 A illustrates the block diagram that can carry out for space multiplexing mode the transmitter unit 900 of transmission processing.Transmitter unit 90 is another embodiment of the transmitter part of access point and user terminal.For space multiplexing mode, same supposition has four transmit antennas and four reception antennas to use, and data can send at four space channels nearly.For each space channel uses different speed according to its transmission capacity.Each rate domain one specific code rate and modulation scheme are associated, and be as shown in Table 25.In the following description, suppose selection N
EIndividual space channel is for transfer of data, wherein N
E≤ N
S≤ min{N
T, N
R.
In sending data processor 710b, framing unit 808 carries out framing to the data of each FCH/RCH grouping in order to be the one or more PHY frames of this grouping generation.Each PHY frame is included in can be at whole N in 6 OFDM code elements
EThe data bit number that sends in the individual space channel.Disarrangement device 810 is upset the data of each transmission channel.Encoder 812 receives through the data of upset and according to selected encoding scheme it is encoded, in order to coded-bit is provided.In one embodiment, use a common encoding scheme to be all N
EThe data of individual space channel are encoded, and by coming the brachymemma coded-bit with different brachymemma patterns, thereby are that different space channels obtains different code rates.Therefore, brachymemma unit 814 brachymemma coded-bits are in order to obtain the code rate of expectation for each space channel.The below is described in further detail the brachymemma of space multiplexing mode.
In space multiplexing mode, according to being the reception SNR that four space channels are realized, can use nearly four different speed for these space channels.Each speed is associated with a specific modulation scheme, and is as shown in Table 25.Each symbol mapped unit 820 is according to the data of shining upon for the certain modulation schemes of correlation space channel selection through interweaving, in order to modulated symbol is provided.In whole four space channels of selecting, symbol mapped unit 820a provides four modulation, symbol streams of four space channels to 820d to sending spatial processor 720b.
Sending spatial processor 720b is that space multiplexing mode is carried out spatial manipulation.For simplicity, below description is assumed to transfer of data utilization rate four transmit antennas, four reception antennas and 48 data subbands.The data subband index is provided by set K, wherein for above-mentioned OFDM sub band structure, and K=± 1 ..., and 6,8..., 20,22 ... 26}.
The model of MIMO-OFDM system can be expressed as:
r(k)＝
H(k)
x(k)+
n(k)，k∈K， (5)
Wherein
r(k) be to have four " reception " vectorial (namely for the code element that four reception antennas by subband k receive
r(k)=[r
1(k) r
2(k) r
3(k) r
4(k)]
T);
x(k) be to have four " transmission " vectorial (namely for the code element that the four transmit antennas by subband k sends
x(k)=[x
1(k) x
2(k) x
3(k) x
4(k)]
T);
H(k) be (N of subband k
R* N
T) channel response matrix; And
n(k) be the additional vector from Gaussian noise (AWGN) of subband k.
Suppose noise vector
n(k) component has zero-mean, and covariance matrix is
Λ n=σ
2 I, wherein
IUnit matrix, σ
2It is noise variance.
The channel response matrix of subband k
H(k) can be expressed as:
H wherein
Ij(k) be the transmitting antenna i of subband k and the connection item between the reception antenna j (being complex gain) (for i ∈ 1,2,3,4} and j ∈ 1,2,3,4}).For simplicity, suppose channel response matrix
H(k) (for k ∈ K) is known, perhaps can both determine by transmitter and receiver.
The channel response matrix of each subband
H(k) can be by " diagonalization ", in order to be this subband acquisition N
SIndividual eigenmodes.This can pass through correlation matrix
H(k) carry out eigen value decomposition and realize,
R(k)=
H H(k)
H(k), wherein
H H(k) expression
H(k) conjugate transpose.Correlation matrix
R(k) eigen value decomposition can be expressed as:
R(k)＝
V(k)
D(k)
V H(k)，k∈K， (7)
Wherein
V(k) be (a N
T* N
T) unitary matrix, its row are
R(k) eigenvector (namely
V(k)=[
v 1(k)
v 2(k)
v 3(k)
v 4(k)], wherein each
v i(k) be the eigenvector of an eigenmodes); And
D(k) be
R(k) (the N of eigenvalue
T* N
T) diagonal matrix.
The characteristic of unitary matrix is
M H M=
IEigenvector
v i(k) (for i ∈ 1,2,3,4}) be also referred to as the transmission space vector of each space channel.
Channel response matrix
H(k) also can come diagonalization with singular value decomposition, be expressed as follows:
H(k)＝
U(k)
∑(k)
V H(k)，k∈K， (8)
Wherein
V(k) be to classify as
HThe matrix of right eigenvector (k);
∑(k) be to comprise
HThe diagonal matrix of singular value (k), they are
DDiagonal element (k) (
R(k) positive square root eigenvalue); And
U(k) be to classify as
HThe matrix of left eigenvector (k).
Singular value decomposition is described Academic publishing house second edition in 1980 by Gilbert Strang in the book that is entitled as " Linear Algebra and Its Applications ".Shown in formula (7) and (8), matrix
V(k) row are
R(k) eigenvector and
H(k) right eigenvector.Matrix
U(k) row are
H(k)
H H(k) eigenvector and
H(k) left eigenvector.
The diagonal matrix of each subband
D(k) comprise the null value of non-negative real-valued and other position on the diagonal.
R(k) eigenvalue is marked as { { λ
1(k), λ
2(k), λ
3(k), λ
4Or { λ (k) }
i(k) }, for i ∈ { 1,2,3,4}.
For 48 data subbands each, can be channel response matrix
H(k) carry out independently eigen value decomposition, (suppose each matrix in order to determine four eigenmodes for this subband
H(k) all be full arrangement).Each diagonal matrix
D(k) four eigenvalues can be sorted, so that { λ
1(k) 〉=λ
2(k) 〉=λ
3(k) 〉=λ
4(k) }, wherein for subband k, λ
1(k) be dominant eigenvalue, λ
4(k) be smallest eigen.When each diagonal matrix
DWhen eigenvalue (k) is sorted, correlation matrix
V(k) also correspondingly ordering of eigenvector (or row).
The set (being that broadband eigenmodes m comprises the eigenmodes m in all subbands) of the eigenmodes of phase same order in all subbands after " broadband " eigenmodes can be defined as sorting." mainly " broadband eigenmodes be after ordering with each matrix
In the eigenmodes that is associated of maximum singular value.
Then form vector
d m, comprise that the m of all 48 data subbands arranges eigenvalue.This vector
d mCan be expressed as:
d m＝[λ
m(-26)...λ
m(-22)...λ
m(22)...λ
m(26)]，m＝{1，2，3，4} (9)
Vector
d 1The eigenvalue that comprises the best or main broadband eigenmodes.For the MIMO-OFDM system that four transmit antennas and four reception antennas are arranged (i.e. 4 * 4 systems), nearly four broadband eigenmodes are arranged.
If the noise variance at receiver place is constant and known for transmitter on working band, then pass through eigenvalue λ
m(k) divided by noise variance σ
2Can determine the reception SNR of each subband of each broadband eigenmodes.For simplicity, suppose that it (is σ that noise variance equals 1
2=1).
For space multiplexing mode, total transmitted power P that can use for transmitter
TotalCan be assigned to the broadband eigenmodes based on various power allocation schemes.In a kind of scheme, total transmitted power P
TotalDistributed to equably all four broadband eigenmodes, made P
m=P
Total/ 4, P wherein
mIt is the transmitted power that is assigned to broadband eigenmodes m.In another kind of scheme, use water filling (water-filling) process total transmitted power P
TotalDistribute to four broadband eigenmodes.
The injecting process distributes power, makes the broadband eigenmodes with higher-wattage receive the most of total transmitted power.The amount of transmit power of distributing to a given broadband eigenmodes depends on that it receives SNR, receives the power gain (or eigenvalue) that SNR depends on again whole subbands of this broadband eigenmodes.The injecting process can distribute the null value transmitted power to the broadband eigenmodes that has enough poor reception SNR.The injecting process is that four broadband eigenmodes receive
β={ β
1, β
2, β
3, β
4, β wherein
mBe the normalization factor of broadband eigenmodes m, and can be expressed as:
As described below, normalization factor β
mAfter using the channel counter-rotating, the transmitted power of distributing to broadband eigenmodes m is remained unchanged.Shown in formula (10), normalization factor β
mCan be based on vector
d mIn eigenvalue and the hypothesis noise variance to equal 1 (be σ
2=1) derives.
Then, the injecting process is based on set
βDetermine to be assigned to total transmitted power of each broadband eigenmodes, so that can optimize spectrum efficiency or some other standard.The transmitted power that the injecting process is distributed to broadband eigenmodes m can be expressed as:
P
m＝α
mP
total，m＝{1，2，3，4} (11)
The power division of four broadband eigenmodes can by
α={ α
1, α
2, α
3, α
4Provide, wherein
And
If set
αIn a more than value is arranged is non-zero, then can select space multiplexing mode.
The process of carrying out water filling is well known in the art, no longer describes here.A bibliography of describing water filling is " the Information Theory and Reliable Communication " that Robert G.Gallager shows, JohnWiley and Sons publishing house, and 1968, it is incorporated into this by reference.
For space multiplexing mode, the speed of each space channel or broadband eigenmodes select can based on: this space channel/broadband eigenmodes is assigned to transmitted power P at it
mThe reception SNR of Shi Shixian.For simplicity, the transfer of data of supposing on the eigenmodes of broadband is below described.The reception SNR of each broadband eigenmodes can be expressed as:
In one embodiment, the speed of each broadband eigenmodes determines based on a form, and this form comprises speed that system supports and the SNR scope of each speed.This form can obtain by Computer Simulation, experiment measuring etc.The special speed that each broadband eigenmodes will be used is the speed in this form, has the SNR of the certain limit of the reception SNR that comprises the broadband eigenmodes.In another embodiment, the speed of each broadband eigenmodes is based on the selection of getting off: the reception SNR of (1) broadband eigenmodes, (2) be used for remedying the variability of evaluated error, mimo channel and the SNR skew of other factors, and (3) speed of supporting and the form of their required SNR.For this embodiment, calculate at first as described above the average received SNR of each broadband eigenmodes, perhaps as on average the calculating of the reception SNR of broadband all subbands of eigenmodes (take dB as unit).In either case, then calculate an operating SNR, equal to receive SNR and SNR skew sum (both are all take dB as unit).Then the required SNR of each speed of operating SNR and system being supported compares.Then be the flank speed in the broadband eigenmodes selection form, its required SNR is less than or equal to operating SNR.The speed that sends diversity mode and wave beam control model also can be determined in a similar manner.
Transmitted power P for each broadband eigenmodes distribution
mCan be distributed in 48 data intersubbands of this broadband eigenmodes, so that the reception SNR approximately equal of all subbands.This power is called as the channel counter-rotating in the non-homogeneous distribution of intersubband.Distribute to the transmitted power P of each subband
m(k) can be expressed as:
β wherein
mIn formula (10), provide.
Shown in formula (13), transmitted power P
mBased on they the channel power inhomogeneous gain be distributed between data subband, channel power gains by eigenvalue λ
m(k) provide, for k ∈ K.Power distributes so that all realize approximately equalised reception SNR at the receiver place for all data subbands of each broadband eigenmodes.The counter-rotating of this channel is carried out independently for each of four broadband eigenmodes.Be reversed in by the channel of broadband eigenmodes in the U.S. Patent application of following common transfer and be described in further detail: submitted on August 27th, 2002 the 10/229th, No. 209 U.S. Patent applications are entitled as " Coded MIMO Systems with Selective Channel Inversion AppliedPer Eigenmode ".
The channel counter-rotating can be carried out in various manners.For all channel counter-rotating, if selected a broadband eigenmodes, then all data subbands are all for transfer of data.For the selective channel counter-rotating, can be a whole or subset of each broadband eigenmodes choice for use data available subband.The selective channel counter-rotating abandons and receives the bad subband that SNR is lower than certain threshold level, and only selected subband is carried out the channel counter-rotating.The selective channel counter-rotating of each broadband eigenmodes is also at the 10/229th of common transfer, describe in No. 209 U.S. Patent applications, this patent was submitted on August 27th, 2002, was entitled as " Coded MIMO Systems with Selective Channel InversionApplied Per Eigenmode ".For simplicity, below description is assumed to each broadband eigenmodes of selecting and carries out all channel counter-rotating.
The used gain of each subband of each broadband eigenmodes can be based on the transmitted power P that distributes to this subband
m(k) determine.The gain g of each data subband
m(k) can be expressed as:
Can be each subband definition pair of horns gain matrix
G(k).This matrix
G(k) comprise the gain of four eigenmodes of subband k along diagonal, and can be expressed as:
G(k)=diag[g
1(k), g
2(k), g
3(k), g
4(k)]
For space multiplexing mode, the transmission of each data subband vector
x(k) can be expressed as:
x(k)＝
V(k)
G(k)
s(k)，k∈K， (15)
Wherein
s(k)＝[s
1(k)s
2(k)s
3(k)s
4(k)]
T，
x(k)＝[x
1(k)x
2(k)x
3(k)x
4(k)]
T
Vector
s(k) comprise four modulated symbols that will send in four eigenmodes of subband k, vector
x(k) comprise four transmission code elements sending from four antennas of subband k.For simplicity, formula (15) does not comprise the employed correction factor of difference of the transmission chain/receive chain that remedies access point and user terminal place, and the below describes in detail.
Fig. 9 B illustrates the block diagram that can carry out for space multiplexing mode transmission spatial processor 720b one embodiment of spatial manipulation.For simplicity, below describe supposition and selected all four broadband eigenmodes.Yet, also can select to be less than four broadband eigenmodes.
In processor 720b, demultiplexer 932 receives and will (be labeled as s in four modulation, symbol streams that four broadband eigenmodes send
1(n) to s
4(n)), for 48 data subbands each is flowed 48 subflows of demultiplexer, and four modulation, symbol streams of each data subband are offered corresponding transmission subband spatial processor 940.Each processor 940 is that a subband is carried out the processing shown in the formula (15).
Send 940, four modulated symbol subflows of subband spatial processor at each and (be labeled as s
1(k) to s
4(k)) be provided for four multiplier 942a to 942d, multiplier also receives the gain g of four eigenmodes of relevant subbands
1(k), g
2(k), g
3(k) and g
4(k).Each g that gains
m(k) can be based on the transmitted power P that distributes to this subband/eigenmodes
m(k) determine, shown in formula (14).Each its g that gains of multiplier 942 usefulness
m(k) come its modulated symbol of convergent-divergent in order to modulated symbol through convergent-divergent is provided.Multiplier 942a offers respectively four beam-shaper 950a to 950d to 942d with four modulated symbol subflows through convergent-divergent.
Each beam-shaper 950 is carried out beam forming, in code element subflow of an eigenmodes transmission of a subband.Each beam-shaper 950 receives a code element subflow s of relevant eigenmodes
m(k) and an eigenvector
v m(k).Particularly, beam-shaper 950a receives the eigenvector of the first eigenmodes
v 1(k), beam-shaper 950d receives the eigenvector of the second eigenmodes
v 2(k), the rest may be inferred.Beam forming is carried out with the eigenvector of relevant eigenmodes.
In each beam-shaper 950, be provided for four multiplier 952a to 952d through the modulated symbol of convergent-divergent, multiplier also receives relevant eigenmodes
v mFour element v of eigenvector (k)
M, 1(k), v
M, 2(k), v
M, 3(k) and v
M, 4(k).Then, each its eigenvector value of multiplier 952 usefulness v
M, j(k) multiply by through the modulated symbol of convergent-divergent so that " through beam forming " code element to be provided.Multiplier 952a offers respectively adder 960a to four code element subflows through beam forming (they will send from four antennas) to 960d to 952d.
Each adder 960 receives four code elements through beam forming of four eigenmodes of each code-element period, and provides through preregulated code element with their additions so that for relevant transmitting antenna.Adder 960a offers respectively buffer/multiplexer 970a to four of four transmit antennas to 970d through preregulated code element subflow to 960d.
Each buffer/multiplexer 970 is that 48 data subbands are from sending subband spatial processor 940a to 940k reception pilot frequency code element with through preregulated code element.Then, for each code-element period, each buffer/multiplexer 970 is respectively 4 pilot subbands, 48 data subbands and 12 and does not use multiplexed 4 pilot frequency code elements of subband, 48 through preregulated code element and 12 zero, in order to form the sequences of one 64 transmission code elements for this code-element period.Each buffer/multiplexer 970 provides one to send code element stream x for a transmit antennas
i(n), wherein send code element stream and comprise 64 modular cascade sequences that send code element.Send code element and can use the correction factor convergent-divergent, in order to remedy the poor, as described below of access point and user terminal place transmission chain/receive chain.The above has described each and has sent the follow-up OFDM modulation of code element stream.
Paralleled code element stream also can send from four transmit antennas, and does not use uncontrolled space multiplexing mode in the spatial manipulation at access point place.For this pattern, can omit beam-shaper 950 and carry out from channel Umklapp process and beam forming.Flow through further OFDM of each modulated symbol processes, and sends from corresponding transmitting antenna.
Uncontrolled space multiplexing mode can be used for various occasions, such as supporting wave beam to control necessary spatial manipulation in the situation that transmitter can not be carried out based on eigenmode decomposition.This may be because transmitter is not yet carried out calibration process, and can not generate enough good estimations of channel, does not perhaps calibrate with eigenmodes and processes.For uncontrolled space multiplexing mode, spatial reuse still is used for improving transmittability, but receiver is carried out spatial manipulation in order to separate independent code element stream.
For uncontrolled space multiplexing mode, spatial manipulation carried out by receiver so that the code element stream of recovering to send.Particularly, user terminal can be realized channel correlation matrix counter-rotating (CCMI) technology, least mean-square error (MMSE) technology, one by one interference cancellation receiver treatment technology or some other receiver space treatment technology.These technology are the 09/993rd of common transfer the, describe in detail in No. 087 U.S. Patent application, this patent was submitted to November 6 calendar year 2001, was entitled as " Multiple-Access Multiple-Input Multiple-Output (MIMO) Communication System ".Uncontrolled space multiplexing mode can be used for down link and ul transmissions.
The Multi-User Dimension multiplexer mode supports to arrive simultaneously on the down link transfer of data of a plurality of user terminals based on " space characteristics " of user terminal.The space characteristics of user terminal is provided by the channel response vector between access point antenna and each user terminal antenna (for each subband).Access point can obtain space characteristics based on the controlled benchmark that user terminal sends.Access point can be processed the space characteristics of the user terminal of expected data transmission, with: transfer of data when (1) selects one group of user terminal to be used on the down link, and (2) derive dominant vector for each independent data stream that will be sent to the selected user terminal.
The dominant vector of Multi-User Dimension multiplexer mode can be derived in every way.Two exemplary schemes are described below.For simplicity, below describe for a subband, suppose that each user terminal is equipped with single antenna.
In the first scheme, access point uses the channel counter-rotating to obtain dominant vector.Access point can be selected N
ApTransmission when individual single antenna user terminal is used on the down link.Access point obtains one 1 * N for each selected user terminal
ApThe capable vector of channel response, and form a N
Ap* N
ApChannel response matrix
H Mu, this matrix has N
ApThe N of individual user terminal
ApIndividual row vector.Then, access point is N
ApIndividual selected user terminal obtains N
ApThe matrix of individual dominant vector
H Steer,
Access point also can send a controlled benchmark to each selected user terminal.Its controlled benchmark of each user terminal processes is estimated channel gain and phase place, and is its single antenna demodulation receiving symbol with channel gain and phase estimation, to obtain the code element through recovering.
In first scheme, access point is decoded in advance and will be sent to N
ApThe N of individual user terminal
ApIndividual code element stream is so that these code element stream are subject to cross-talk hardly at the user terminal place.Access point can be N
ApIndividual selected user terminal forms channel response matrix
H Mu, and right
H MuCarry out the OR Factorization, so that
H Mu=
F Tri Q Mu, wherein
T TriWith
Q MuIt is unitary matrix.Access point is then used matrix
T TriN in advance decodes
ApIndividual data code element stream is to obtain N
ApIndividual code element stream through pre decoding
a, and use unitary matrix
Q MuThe code element stream of further processing through pre decoding supplies to send to N with acquisition
ApThe N of individual user terminal
ApIndividual transmission code element stream.Equally, access point also can send a controlled benchmark to each user terminal.Each user terminal uses controlled benchmark to its receiving symbol coherent demodulation so that the code element of acquisition through recovering.
For the up link in the Multi-User Dimension multiplexer mode, access point can process with the MMSE receiver, interference cancellation or some other receiver treatment technology recover by N one by one
ApThe N that individual user terminal sends simultaneously
ApIndividual code element stream.Access point can be estimated the uplink channel responses of each user terminal, and estimates to carry out the receiver space processing and come the scheduling uplink transmission with channel response.Each single antenna user terminal can send an orthogonal guide frequency in up link.From N
ApThe uplink pilot of individual user terminal can be in time and/or quadrature on the frequency.Time quadrature is realized like this: cover its uplink pilot by making each terminal with an orthogonal sequence distributing to this user terminal.Frequency orthogonal realizes like this: make each user terminal send its uplink pilot at a different set of subband.Ul transmissions from user terminal should be in access point place time proximity alignment (for example time unifying in the paging prefix).
3. wave beam control model-transmission processing
Figure 10 A illustrates the block diagram that can carry out for the wave beam control model transmitter unit 1000 of transmission processing.Transmitter unit 1000 is in addition embodiment of the transmitter section of access point and user terminal.
In sending data processor 710c, framing unit 808 to the data framing of each FCH/RCH grouping in order to be the one or more PHY frames of this grouping generation.Disarrangement device 810 is then upset for the data of each transmission channel.Encoder 812 is then encoded through the data of framing according to selected encoding scheme, in order to coded-bit is provided.Then, brachymemma unit 814 brachymemma coded-bits are in order to be the code rate that the used broadband eigenmodes of transfer of data obtains expectation.Coded-bit from brachymemma unit 818 is interleaved between all data subbands.Then, symbol mapped unit 820 shines upon the data through interweaving in order to modulated symbol is provided according to selected modulation scheme.Then, for the wave beam control model, send spatial processor 720c modulated symbol is carried out transmission processing.
The wave beam control model can be used at a space channel or the broadband eigenmodes sends data-described space channel or the broadband eigenmodes generally is the space channel that is associated with the dominant eigenvalue of all data subbands.If the transmit power assignment to the broadband eigenmodes is only being gathered
aOne of middle generation non-zero then can select the wave beam control model.And space multiplexing mode is carried out beam forming based on its eigenvector to each selected eigenmodes of each subband, the wave beam control model is carried out wave beam control based on " standardized " eigenvector, and its principle is to make the eigenmodes of each subband send data in this single eigenmodes.
For main eigenmodes, each eigenvector
v 1(k) four elements of (for k ∈ K) may have different sizes.Thereby the transmission vector of four every antennas may have different sizes, each is described send vector comprise a given transmitting antenna all data subbands through preregulated code element.If the transmitted power of each transmitting antenna is restricted the restriction of power amplifier (for example because), the beam forming technique gross power that may not exclusively use every antenna to use then.
The wave beam control model is only used the eigenvector from main eigenmodes
v 1(k) phase information of (for k ∈ K), and to each eigenvector standardization, so that whole four units in the eigenvector have equal size.Subband k through standardized eigenvector
Can be expressed as:
Wherein A is a constant (for example A=1); And
θ
i(k) be the phase place of the subband k of transmitting antenna i, be expressed as:
Shown in formula (17), vector
In the phase place of each element from eigenvector
v 1(k) respective element obtains (that is, θ
i(k) from v
1, i(k) obtain, wherein
v 1(k)=[v
1,1(k) v
1,2(k) v
1,3(k) v
Isosorbide-5-Nitrae(k)]
T).
Also can carry out the channel counter-rotating for the wave beam control model, so that can use a common speed for all data channels.For the wave beam control model, distribute to the transmitted power of each data subband
Can be expressed as:
Wherein
After using the channel counter-rotating, to keep the constant normalization factor of total transmitted power;
Normalization factor
Can be expressed as:
Transmitted power
Can be given P
1=P
Total/ 4 (being the uniform distribution of total transmitted power between four transmit antennas).
Power gain
Can be expressed as:
For 48 data subbands, the channel counter-rotating causes
Power division, for k ∈ K.So the gain of each data subband can be given
For the wave beam control model, the transmission of each subband vector
x(k) can be expressed as:
Be for simplicity equally, formula (21) does not comprise the correction factor be used to the difference of the transmission chain/receive chain that remedies access point and user terminal place.
Shown in formula (16), the standardization control of each subband vector
Four elements equal size may be arranged, but different phase places may be arranged.Therefore, wave beam is controlled to be each subband and generates a transmission vector
x(k),
x(k) four elements have identical size but different phase places may be arranged.
Figure 10 B illustrates the block diagram that can carry out for the wave beam control model transmission spatial processor 720c one embodiment of spatial manipulation.
In processor 720c, demultiplexer 1032 receives modulation, symbol streams s (n) and its multichannel is resolved into 48 subflows (being labeled as s (1) to s (k)) of 48 data subbands.Each code element subflow is provided for corresponding transmission subband wave beam control processor 1040.Each processor 1040 is that a subband is carried out the processing shown in the formula (14).
In each sent subband wave beam control processor 1040, the modulated symbol subflow was provided for multiplier 1042, and multiplier 1042 also is relevant subband receiving gain
Then, multiplier 1042 usefulness gain
The convergent-divergent modulated symbol is to obtain the modulated symbol through convergent-divergent, and the latter then is provided for wave beam control unit 1050.
Wave beam control unit 1050 also receives the standardization eigenvector of relevant subbands
In wave beam control unit 1050, be provided for four multiplier 1052a to 1052d through the modulated symbol of convergent-divergent, the latter also receives respectively the standardization eigenvector
Four elements
With
Its standardization eigenvector value of each multiplier 1052 usefulness
Multiply by its through the modulated symbol of convergent-divergent to provide through preregulated code element.Multiplier 1052a offers respectively buffer/multiplexer 1070a to four to 1070d through preregulated code element subflow to 1052d.
For 48 data subbands, each buffer/multiplexer 1070 is from sending subband wave beam control processor 1040a to 1040k reception pilot frequency code element with through preregulated code element, pilot tone and multiplexed through preregulated code element and null value, and provide one to send code element stream x for a transmit antennas for each code-element period
i(n).Each follow-up OFDM that sends code element stream modulates as mentioned above.
The processing of wave beam control model is described in further detail in the common U.S. Patent application of transferring the possession of, this patent was submitted on August 27th, 2002, sequence number is 10/228,393, is entitled as " Beam-Steering and Beam-Formingfor Wideband MIMO Systems ".System also can be designed to support the beam forming pattern, uses whereby eigenvector rather than standardized vector to send data flow in main eigenmodes.
4.PHY the framing of frame
Figure 11 A illustrates an embodiment of framing unit 808, and framing unit 808 is used for before sending data processor to carry out subsequent treatment the data of each FCH/RCH grouping being carried out framing.This framing function is for the upper message that sends of BCH, FCCH and RACH and bypass.The framing unit generates an integer PHY frame for each FCH/RCH grouping, and wherein for embodiment described here, each PHY frame strides across 6 OFDM code elements.
For diversity and wave beam control model, only use a space channel or broadband eigenmodes for transfer of data.The speed of this pattern is known, can calculate the information bit that may send in the pay(useful) load of each PHY frame.For space multiplexing mode, can use a plurality of space channels for transfer of data.Because the speed of each space channel is known, therefore for all space channels, can calculate the information bit that in the pay(useful) load of each PHY frame, sends.
Shown in Figure 11 A, the information bit of each FCH/RCH grouping (is labeled as i
1i
2i
3i
4...) offer CRC maker 1102 and multiplexer 1104 in the framing unit 808.CRC maker 1102 is for the bit in the header (if there is) of each PHY frame and the pay(useful) load field generates a crc value, and the CRC bit is offered multiplexer 1104.Multiplexer 1104 receives information bit, CRC bit, preamble bit and filling bit (for example null value), and provides these bits based on the PHY control frame signal with correct order, as shown in Figure 6.By directly providing information bit by multiplexer 1104, can bypass framing function.Through framing and not the bit of framing (be labeled as d
1d
2d
3d
4...) be provided for disarrangement device 810.
5. upset
In one embodiment, the data bit of each transmission channel is in the encoder multilated.Upset is the data randomization, so that the complete one or entirely zero long sequence that forms does not send.This can reduce the peak value of OFDM waveform to the variation of average power.Upset can be omitted one or more transmission channels, and also can optionally be enabled and forbid.
Figure 11 A also illustrates an embodiment of disarrangement device 810.In this embodiment, disarrangement device 810 is realized a maker multinomial:
G(x)＝x
7+x
4+x (22)
Also can use other Generator polynomial, this within the scope of the invention.
Shown in Figure 11 A, disarrangement device 810 comprises that seven delay element 1112a of order coupling are to 1112g.For each clock cycle, two bits preserving among 1114 couples of delay element 1112d of adder and the 1112g are carried out mould 2 and are added, and a upset bit is offered delay element 1112a.
Through framing/bit (d of framing not
1d
2d
3d
4) being provided for adder 1116, the corresponding bit of upsetting of adder 1116 usefulness is to each bit d
nExecution mould 2 adds, in order to the bit q through upsetting is provided
n Disarrangement device 810 provides once the sequence that upsets bit, is labeled as q
1q
2q
3q
4....
At the place that begins of each tdd frame, the initial condition of disarrangement device (being that delay element 1112a is to the content of 1112g) is set as the non-zero number of one 7 bits.As shown in BCH message, three highest significant positions (MSB) (being that delay element 1112e is to 1112f) always are set as one (" 1 "), and four least significant bits (LSB) are set as the tdd frame counter.
6. coding/brachymemma
In one embodiment, use single base code before transmission, data to be encoded.This base code is that a code rate generates coded-bit.All other code rates (as shown in Table 25) that system supports can by or the repeated encoding bit or or the brachymemma coded-bit obtain.
Figure 11 B illustrates an embodiment of the encoder 812 of the base code that can realize system.In this embodiment, base code is that speed is 1/2, limited length is the convolutional encoding of 7 (K=7), and maker is 133 and 171 (octal system).
In encoder 812, multiplexer 1120 receives and multiplexed bit and tail bit (for example null value) through upsetting.Encoder 812 comprises that also six delay element 1122a of order coupling are to 1122f.Four adder 1124a are coupled to 1124d also order, and are used for realizing the first maker (133).Similarly, four adder 1126a are coupled to 1126d also order, and are used for realizing the second maker (171).Shown in Figure 11 B, adder further is coupled to delay element in the mode that realizes two makers 133 and 171.
Bit through upsetting is offered the first delay element 1122a and adder 1124a and 1126a.For each clock cycle, adder 1124a carries out moulds 2 to 1124d to four previous bits preserving among the bit that arrives and delay element 1122b, 1122c, 1122e and the 1122f and adds, in order to provide the first coded-bit for this clock cycle.Similarly, adder 1126a carries out moulds 2 to 1126d to four previous bits preserving among the bit that arrives and delay element 1122a, 1122b, 1122c and the 1122f and adds, in order to provide the second coded-bit for this clock cycle.The coded-bit that the first maker generates is marked as a
1a
2a
3a
4..., the coded-bit that the second maker generates is marked as b
1b
2b
3b
4....Then, multiplexer 1128 receives two coded bit streams from two makers, and they are multiplexed into single encoded bit stream, and the latter is marked as a
1b
1a
2b
2a
3b
3a
4b
4....For each bit q through upsetting
n, generate two coded-bit a
nAnd b
n, this produces code rate 1/2.
Figure 11 B also illustrates an embodiment that can generate based on 1/2 basic bit rate the employed repetition of other code rate/brachymemma unit 814.In unit 814, be provided for repetitive 1132 and brachymemma 1134 from the coded-bit of the speed 1/2 of encoder 812.Repetitive 1132 repeats each speed 1/2 coded-bit once, to obtain efficient coding speed 1/4.The coded-bit of some speed 1/2 is deleted based on specific brachymemma pattern in brachymemma unit 1134, in order to the code rate of expectation is provided.
Table 30 is listed the exemplary brachymemma pattern that can be used for the various code rates that system supports.Also can use other brachymemma pattern, this within the scope of the invention.
Table 30
In order to obtain code rate k/n, brachymemma unit 1134 provides n coded-bit for the coded-bit of every group of 2k speed 1/2 receiving from encoder 812.Like this, 2k-n coded-bit of deletion from every group of 2k coded-bit.To come mark by zero the brachymemma pattern from the bit of every group of deletion.For example, for obtaining code rate 7/12, always delete two bits in every group of 14 coded-bits of own coding device 812, the bit of deleting is the 8th and the 14th coded-bit in the group, such as brachymemma pattern " 11111110111110 " institute mark.If the code rate of expectation is 1/2, then do not carry out brachymemma.
Multiplexer 1136 receives from repetitive 1132 with from the coded bit stream of brachymemma unit 1134.Then, if the expectation code rate is 1/4, then multiplexer 1136 provides the coded-bit from repetitive 1132, if the expectation code rate is 1/2 or higher, then multiplexer 1136 provides the coded bit stream from brachymemma unit 1134.
Except above-mentioned coding and brachymemma pattern, also can use other coding and brachymemma pattern, this is within the scope of the invention.For example, can come data are encoded with Turbo code, piece coding, some other yards or their combination in any.Equally, can use different encoding schemes for different transmission channels.For example, can use conventional coding for Common transport channel, can use the Turbo coding for dedicated transmission channel.
7. interweave
The coded-bit that be sent out in one embodiment, is interleaved at 48 data intersubbands.For diversity and wave beam control model, between all data subbands, send and the coded bit stream that interweaves.For space multiplexing mode, nearly can send nearly four coded bit streams on four space channels.Interweave and to carry out independently for each space channel, so that each coded bit stream is interleaved between all data subbands of the space channel that is used for this bit stream of transmission.Table 29 illustrates the exemplary coded-bit-allocation of subbands that interweaves that can be used for all transmission modes.
In one embodiment, within each interweaves the interval, interweave in all 48 data intersubbands execution.For this embodiment, every group of 48 coded-bits are all expanded at 48 data subbands in the stream, so that frequency diversity to be provided.48 coded-bits in every group can be assigned to index 0 to 47.Each coded-bit index is associated with a corresponding subband.All coded-bits with a particular index all are sent out at relevant subband.For example, the first coded-bit (index is 0) in every group is sent out at subband-26, and the second coded-bit (index is 14) is sent out at subband 1, and the 3rd coded-bit (index is 2) is sent out at subband-17, and the rest may be inferred.This interleaving scheme can be used for diversity mode, wave beam control model and space multiplexing mode.Other interleaving scheme for spatial reuse is described below.
Interweave or or can carry out in time in addition.For example, after interweaving between data subband, the coded-bit of each subband can further be interweaved (for example on a PHY frame or PDU) so that time diversity to be provided.For space multiplexing mode, also can interweave in a plurality of space channels execution.
In addition, can adopt at the dimension of QAM code element to interweave, so that form the different bit positions that the coded-bit of QAM code element is mapped as the QAM code element.
8. symbol mapped
Table 31 illustrates the symbol mapped of each modulation scheme that system supports.For each modulation scheme (except BPSK), the bit of half is mapped as homophase (I) component, and second half bit is mapped as quadrature (Q) component.
In one embodiment, can define based on Gray (Gray) mapping the signal group of stars of each modulation scheme of supporting.According to gray mappings, the consecutive points in the signal group of stars (in I and the Q component) only differ a bit position.Gray mappings has reduced number of bit errors for situation about more may make mistakes, and error situation is mapped as near the tram a position corresponding to receiving symbol, only can mistake receive a coded-bit in this situation.
Table 31
The I of each modulation scheme shown in the table 31 and Q value one normalization factor k
NormConvergent-divergent is so that the average power of all signaling points equals one in the coherent signal group of stars.Also can use the quantized value of the normalization factor of the modulation scheme of supporting.So the modulated symbol s in the signal specific group of stars has following form:
s＝(I+jQ)·K
norm，
Wherein I and Q are the values of a signal group of stars in the table 31.
For given PDU, being modulated at may be different between PDU, and also may be different for the employed a plurality of space channels of transfer of data.For example, for BCH PDU, can use different modulation schemes for beacon pilot frequency, MIMO pilot tone and BCH message.
9. the processing of space multiplexing mode
For space multiplexing mode, a PDU can be sent out at a plurality of space channels.Can come deal with data with various schemes, be used for sending at a plurality of space channels.Two specific processing schemes of space multiplexing mode are described below.
In the first processing scheme, carry out coding and brachymemma by each space channel, in order to realize the code rate of expectation for each space channel.The N that transfer of data will be used
EIndividual space channel is arranged from being up to minimum reception SNR.At first encode the data of whole PDU to obtain speed 1/2 coded bit stream.Then the brachymemma coded-bit is in order to obtain the code rate of expectation for each space channel.
For N
EIndividual space channel, brachymemma can be carried out with order, from the space channel of best (i.e. the highest SNR) to the poorest (being minimum SNR).Particularly, brachymemma is at first carried out for the optimal spatial channel with the highest reception SNR in the brachymemma unit.When having generated the coded-bit of correct number for the optimal spatial channel, brachymemma is just carried out for having time inferior good space channel of high reception SNR in the brachymemma unit.This process continues, until all N
ETill the coded-bit of individual space channel has all generated.The order of brachymemma is to receive SNR to minimum receive SNR from maximum, and no matter how much employed specific coding speed of each space channel is.
For the example shown in the table 28, at first with the base code of speed 1/2 3456 information bits that will send in total PHY frame are encoded, in order to obtain 6912 coded-bits.Front 3168 coded-bits come brachymemma to obtain 2304 coded-bits with the brachymemma pattern of code rate 11/16, and the latter provides in the PHY of the first space channel frame.Then carry out brachymemma to obtain 1728 coded-bits with the brachymemma pattern of code rate 3/4 to following 2592 coded-bits, the latter provides in the PHY of second space channel frame.Then 864 coded-bits are to obtain 576 coded-bits then to come brachymemma with the brachymemma pattern of code rate 3/4, and the latter provides in the PHY of the 3rd space channel frame.Then last 288 coded-bits that come brachymemma PHY frame with the brachymemma pattern of code rate 1/2 to be obtaining 288 coded-bits, and the latter in the end provides in the PHY frame of a space channel.These four independent PHY frames are further processed and are sent out at four space channels.Then carry out in a similar manner the brachymemma of next total PHY frame.The first processing scheme can realize with the transmission data processor 710b among Fig. 9 A.
In the second processing scheme, be encoding and brachymemma to carrying out of subband.In addition, coding and brachymemma are in the whole selected space channel cocycle of every pair of subband.
Figure 11 C illustrates a block diagram, and it has illustrated the transmission data processor 710d that realizes the second processing scheme.812 pairs of convolutional encodings of carrying out speed 1/2 from the bit through upsetting of disarrangement device 810 of encoder.Each space channel is assigned to a special speed, and this special speed is associated with the particular combinations of code rate and modulation scheme, and is as shown in Table 25.Make b
mExpression is for the number of coded bits of each modulated symbol of space channel m (or ground of equal value, the number of coded bits that sends at each data subband of space channel m), r
mThe employed code rate of representation space channel m.b
mValue depend on the group of stars size of the employed modulation scheme of space channel m.Particularly, for BPSK, QPSK, 16-QAM, 64-QAM and 256-QAM, b
mEqual respectively 1,2,4,6 and 8.
In case the 4b of each buffer 813 usefulness correlation space channel
mr
mIndividual coding chip is filled, and the coded-bit in just can the brachymemma buffer is in order to obtain the code rate of this space channel.Because 4b
mr
mThe coded-bit of individual speed 1/2 has striden across an integer truncated human cyclin of each brachymemma pattern, therefore after the brachymemma of each space channel m, in fact provides 2b
mIndividual coded-bit.Then, the 2b of each space channel
mIndividual coded-bit just distributes (or interweaving) at data subband.
In one embodiment, once in one group of 6 subband, each space channel execution is interweaved.Coded-bit after the brachymemma of each space channel can arranged sequentiallyly be c
i, for i=0,1,2 ....For each space channel is kept a counter C
mSo that every group of 6b that the brachymemma unit is provided for this space channel
mIndividual coded-bit is counted.For example, for b
m=2 QPSK, the coded-bit c that provides for the brachymemma unit
0To c
11, counter can be set as C
m=0, for coded-bit c afterwards
12To c
23, can be set as C
m=1, the rest may be inferred.The Counter Value C of space channel m
mCan be expressed as:
C
m＝
i/(6b
m)
mod8 (23)
In order to determine coded-bit c
iBe assigned to which subband, the code index of at first following definite coded-bit:
Bit index=(imod6)+6C
m(24)
Then, bit index use table 29 is mapped to corresponding subband.
For upper example, first group of 6 coded-bit c
0To c
5Be associated respectively second group of 6 coded-bit c with bit index 0 to 5
6To c
11Also be associated to 5 with bit index 0 respectively.Shown in table 29, coded-bit c
0And c
6Can be mapped to subband-26, coded-bit c
1And c
7Can be mapped to subband 1, the rest may be inferred.Then begin spatial manipulation for these first group of 6 subband.The 3rd group of 6 coded-bit c
12To c
17(C
m=1) is associated respectively the 4th group of 6 coded-bit c with bit index 6 to 11
18To c
23Also be associated to 11 with bit index 6 respectively.Coded-bit c
12And c
18Can be mapped to subband-25, coded-bit c
13And c
19Can be mapped to subband 2, the rest may be inferred.Then begin spatial manipulation for 6 subbands of this next group.
Numeral 6 in the formula (24) comes to carry out in the group of 6 subbands and interweaves.(mod8) computing in the formula (23) comes from for 48 data subbands 8 groups that interweave.Because each circulation of the demultiplexer 816 shown in Figure 11 C produces two subbands that enough coded-bits are filled each broadband eigenmodes, therefore need altogether 24 cycles to provide 48b for an OFDM code element of each space channel
mIndividual coded-bit.
Once in the group of 6 subbands, interweave and to reduce processing delay.Particularly, in case every group of 6 subbands are available, can begin spatial manipulation.
In other embodiments, once can be at N
BCarry out for each space channel in the group of individual subband and interweave, wherein N
BCan be that arbitrary integer is (for example for interweaving N on whole 48 data subbands
BCan equal 48).
VI. calibration
For the TDD system, down link and up link are shared identical frequency band in the mode of time division duplex.In this situation, there is height correlation in half between the channel response of down link and up link.Should relevant can be used to simplify channel estimating and spatial manipulation.For the TDD system, each subband of supposing Radio Link is reciprocal.Namely, if
H(k) expression for the channel response matrix of subband k from antenna array A to antenna array B, then reciprocal channel mean from antenna array B to antenna array A joint by
H(k) transposition provides, namely
H T(k).
Yet the response of access point place sending and receiving chain (gain and phase place) is general different from the response of user terminal place sending and receiving chain.Can carry out calibration and determine frequency response poor of the sending/receiving chain at access point and user terminal place, and remedy this difference, so that can be according to representing each other through down link and the uplink response of calibrating.In case calibrated and remedied the sending/receiving chain, the dominant vector that just can use the tolerance of a link (for example down link) to derive another link (for example up link).
" effectively " down link and uplink channel responses
H Dn(k) and
H Up(k) comprise the response of the sending and receiving chain that access point and user terminal place are available, and be expressed as:
H dn(k)＝
R ut(k)
H(k)
T ap(k)，k∈K， (25)
H up(k)＝
R ap(k)
H T(k)
T ut(k)，k∈K，
Wherein
T Ap(k) and
R Ap(k) be N
Ap* N
ApDiagonal matrix, its be for subband k, respectively with the N of access point place
ApThe transmission chain of root antenna and the item of the complex gain that receive chain is associated;
T Ut(k) and
R Ut(k) be N
Ut* N
UtDiagonal matrix, its be for subband k, respectively with the N of user terminal place
UtThe transmission chain of root antenna and the item of the complex gain that receive chain is associated; And
H(k) be the N of down link
Ut* N
ApChannel response matrix.
Two formula in the combinatorial formula collection (25) obtain following relational expression:
H up(k)
K ut(k)＝(
H dn(K)
K ap(k))
T，k∈K， (26)
Wherein
And
The left side of formula (26) represents the channel response of " reality " calibration on the up link, and the right represents the transposition of the channel response of " reality " calibration on the down link.Shown in formula (26), use respectively diagonal matrix to effective down link and uplink channel responses
K Ap(k) and
K Ut(k), the enough transposition each other of energy represent the channel response of the calibration of down link and up link.(the N of access point
Ap* N
Ap) diagonal matrix is receive chain response
R Ap(k) with the response of transmission chain
T Ap(k) ratio (namely
), wherein this ratio one by one element draw.Similarly, (the N of user terminal
Ut* N
Ut) diagonal matrix is receive chain response
R Ut(k) with the response of transmission chain
T Ut(k) ratio.
Matrix
K Ap(k) and
K Ut(k) comprise the value of the difference that can remedy access point and user terminal place sending/receiving chain.So this can be represented by the channel response of another link the channel response of a link, shown in formula (26).
Can carry out calibration and determine matrix
K Ap(k) and
K Ut(k).Generally speaking, real channel response
H(k) and sending/receiving chain response be unknown, can not be accurately or easily determine them.But can estimate effective down link and uplink channel responses based on the pilot tone that sends on down link and the up link respectively
H Dn(k) and
H Up(k), as described below.Then as described below, can estimate based on down link and uplink channel responses
With
Come derivational matrix
K Ap(k) and
K Ut(k) estimation, the latter is called correction matrix
With
Matrix
With
The correction factor that comprises the difference that can remedy access point and user terminal place sending/receiving chain.
" calibration " down link and uplink channel responses that user terminal and access point observe are expressed as respectively:
Wherein
H Cdn T(k) and
H Cup(k) be the estimation of the channel response expression formula of " reality " calibration in the formula (26).The expression formula of use formula (26) is come two formula in the combinatorial formula collection (27), can get
Relational expression
Accuracy depend on matrix
With
Accuracy, the latter depends on again that generally down link and uplink channel responses estimate
With
Quality.
Calibration can be carried out with various schemes.For clear, a specific calibration program is described below.In order to carry out calibration, user terminal at first obtains timing and the frequency of access point based on the upper beacon pilot frequency that sends of BCH.Then, user terminal sends a message so that the calibration process of beginning and access point at RACH.Calibration can be carried out concurrently with registration/checking.
Because the frequency band that the frequency response of access point and user terminal place sending/receiving chain is generally noted at great majority is level and smooth, so the phase/gain of sending/receiving chain is poor can characterize with a small amount of subband.Calibration can to 4,8,16,48 or the subband of some other quantity carry out, this quantity is specified in the message that is sent out to begin to calibrate.Calibration also can be carried out pilot subbands.The calibration constants of clearly not carrying out the subband of calibration on it can be by calculating the subband interpolation of calibration.For clear, below be assumed to all data subbands and all carry out calibration.
For calibration, access point distributes the time of sufficient amount to user terminal on RACH, add a message so that transmission has the up link MIMO pilot tone of enough durations.The duration of up link MIMO pilot tone may be depended on the sub band number of carrying out thereon calibration.For example, if four subbands are carried out calibration, then 8 OFDM code elements can be that enough, more subbands may need more (for example 20) OFDM code element.Total transmitted power is generally fixed, if therefore send the MIMO pilot tone at a small amount of subband, then can use the transmitted power of a greater number for each of these subbands, and the SNR of each subband is very high.On the contrary, if send the MIMO pilot tone at a large amount of subbands, then can use for each subband the transmitted power of small amount, the SNR of each subband is very poor.If the SNR of each subband is enough high, then for the MIMO pilot tone sends more OFDM code element, and in these OFDM code elements of receiver place integration in order to be the higher total SNR of this subband acquisition.
Then, user terminal sends a MIMO pilot tone at RCH, and access point derives for each data subband the estimation of efficient uplink channel response with it
Uplink channel responses is estimated to be quantized (for example be quantified as the complex values of 12 bits, have homophase (I) and quadrature (Q) component) and to be sent to user terminal.
User terminal also derives for each data subband the estimation of active downlink channel response based on the upper downlink mimo pilot tone that sends of BCH
Obtaining the estimation of effective up link and downlink channel response for all data subbands
With
After, user terminal is determined correction factor for each data subband
With
They are access in respectively a little and user terminal uses.Can be updating vector
Only be defined as and comprise
Diagonal element, and updating vector
Only be defined as and comprise
Diagonal element.
Correction factor can derive in every way, comprises by the matrix ratio calculating and MMSE calculating.These two kinds of computational methods all are described in further detail below.Also can use other computational methods, this within the scope of the invention.
1. the matrix ratio calculates
In order to estimate according to effective down link and uplink channel responses
With
Determine updating vector
With
At first calculate (a N for each data subband
Ut* N
Ap) matrix
C(k), as follows:
Wherein ratio one by one element draw.Therefore
C(k) each element can followingly calculate:
Wherein
Be
(i, j) individual (OK, row) element,
Be
(i, j) individual element, c
I, j(k) be
C(k) (i, j) individual element.
So, the updating vector of access point
Equal
CThe average of standardization row (k).At first use first element in the delegation to N in this row
ApEach of individual element is carried out convergent-divergent, thereby right
C(k) the column criterion of whenever advancing.Like this, if
Be
C(k) i is capable, then standardized row
Can be expressed as:
So the average of standardization row is N
UtIndividual standardization row sum is divided by N
Ut, be expressed as follows:
Since standardization, therefore
First element be one.
The updating vector of user terminal
Equal
CThe mean value of the inversion of standardization row (k).At first use vector
J element (mark K
Ap, j, j(k) be) each element in the row is carried out convergent-divergent, thus right
C(k) every row carry out standardization.Like this, if
Be
C(k) j is capable, then standardized row
Can be expressed as:
So the mean value of the inversion of standardization row is N
ApThe sum reciprocal of individual standardization row is divided by N
Ap, be expressed as follows:
Wherein standardization is listed as
Inverse carry out by element.
2.MMSE calculate
Calculate correction factor for MMSE
With
Estimate from effective down link and uplink channel responses
With
Middle derivation, thus make mean square error (MSE) minimum between the uplink channel responses of the downlink channel response of calibration and calibration.This condition can be expressed as follows:
Also can write:
Wherein because
The pair of horns matrix, therefore
Formula (34) suffers restraints:
First element be set as one (namely
)。If there is not this constraint, then can obtain common solution, matrix
With
All elements all be set as zero.In formula (34), at first obtain matrix
Y(k):
Then be matrix
Y(k) N
ApN
UtIndividual each obtain absolute value square.
For the subband of each appointment is carried out the correction factor that MMSE calculates to obtain this subband
With
The MMSE that a subband is described below calculates.For simplicity, omit in the following description subband index k.Equally for simplicity, downlink channel response is estimated
Element be marked as { a
Ij, uplink channel responses is estimated
Element be marked as { b
Ij, matrix
Diagonal element be marked as { u
i, matrix
Diagonal element be marked as { v
i, i={1...N wherein
Ap) and j={1...N
Ut).
Can rewrite mean square error from formula (34), as follows:
Same constraints is u
1=1.The local derviation of getting formula (35) by reference u and v goes out and partial derivative is made as zero, thereby obtains least mean-square error.The result of these computings is following formulary:
In formula (36a), u
1=1, so do not have partial derivative in this situation, index i gets N from 2
Ap
Formulary (36a) and (36b) in (N
Ap+ N
Ut-1) set of individual formula can represent more easily with matrix form, and is as follows:
A y＝
z， (37)
Wherein
Matrix
AComprise (N
Ap+ N
Ut-1) OK, front N
Ap-1 row is corresponding to the N in the formulary (36a)
Ap-1 formula, last N
UtRow is corresponding to the N in the formulary (36b)
UtIndividual formula.Particularly, matrix
AThe first row generate from formulary (36a) according to i=2, the second row generates according to i=3, the rest may be inferred.Matrix
AN
ApRow generates from formulary (36b) according to j=1, and the rest may be inferred, and last column is according to j=N
UtGenerate.As implied above, matrix
AEvery and vectorial
zEvery can be based on matrix
With
In every and draw.
Correction factor is included in vector
yIn, following drawing:
y＝
A -1 z (38)
The result that MMSE calculates is the correction matrix that makes the down link of calibration and the mean square error minimum in the uplink channel responses
With
Shown in formula (34).Because matrix
With
Estimate based on down link and uplink channel responses
With
Obtain, so correction matrix
With
Quality depend on channel estimating
With
Quality.The MIMO pilot tone is average in order to obtain at the receiver place
With
More accurately estimation.
Calculate the correction matrix that obtains based on MMSE
With
Generally good than calculating the correction matrix that obtains based on the matrix ratio.In the situation that some channel gains are very little and the tolerance noise that channel gain is demoted greatly is especially true.
3. in rear calculating
Can determine a pair of updating vector for each data subband
With
Because adjacent subband may be correlated with, therefore calculate simplification.For example, can carry out calculating for every n subband rather than for each subband, wherein n can be determined by the intended response of sending/receiving chain.If carry out calibration for being less than total data and pilot subbands, then the correction factor of " not calibration " subband can be by obtaining for " calibration " subband interpolation correction factor.
Also can be respectively access point and user terminal derivation updating vector with various other calibration programs
With
Yet such scheme can be that access point is derived " compatible " updating vector when calibration is carried out by different user terminals.
After derivation, user terminal is the updating vector of all data subbands
Beam back access point.If access point is calibrated (for example by other user terminal), then upgrade current updating vector with the updating vector that newly receives.Like this, if access point uses updating vector
Send the MIMO pilot tone, user terminal is determined new updating vector from this MIMO pilot tone
Updating vector after then upgrading is current and new the amassing of updating vector, namely
Wherein multiplication is by one by one element ground execution.Then, the updating vector after the renewal
Can be access in a use, until they are upgraded again.
Updating vector
With
Can be derived by same user terminal or different user terminals.In one embodiment, the updating vector after the renewal is defined as
Wherein multiplication is by one by one element ground execution.In another embodiment, the updating vector after the renewal can be redefined into
Wherein α is used to provide average weighted factor (for example 0＜α＜1).If it is not frequent that calibration is upgraded, then α may be best close to 1.If calibration is upgraded frequently but made an uproar, then less α value can be better.Then, the updating vector after the renewal
Be access in a use, until they are upgraded again.
Access point and user terminal use their corresponding updating vectors
With
Perhaps corresponding correction matrix
With
(for k ∈ K) convergent-divergent modulated symbol before transmission, as described below.Formula (27) illustrates down link and the uplink channel of the calibration that user terminal and access point observe.
VII. spatial manipulation
After carrying out calibration and remedying difference in the sending/receiving chain, can be the spatial manipulation at TDD system simplification access point and user terminal place.As mentioned above, the downlink channel response of calibration is
The uplink channel responses of calibration is
1. process in the up link space
The uplink channel responses matrix of calibration
H Cup(k) singular value decomposition can be expressed as:
Wherein
U Ap(k) be
H Cup(the N of left side eigenvector (k)
Ap* N
Ap) unitary matrix;
∑(k) be
H Cup(the N of singular value (k)
Ap* N
Ut) diagonal matrix; And
V Ut(k) be
H Cup(the N of the right eigenvector (k)
Ut* N
Ut) unitary matrix.
Correspondingly, the downlink channel response matrix of calibration
H Cdn(k) singular value decomposition can be expressed as:
Matrix
V Ut *(k) and
U Ap *(k) be respectively
H CdnThe matrix of the left side (k) and the right eigenvector.Shown in formula (39) and (40) and based on above description, the matrix of the left side of a link and the right eigenvector is respectively the complex conjugate of the matrix of the right of another link and left side eigenvector.Matrix
V Ut(k),
V Ut *(k),
V Ut T(k) and
V Ut H(k) be matrix
V Ut(k) multi-form, matrix
U Ap(k),
U Ap *(k),
U Ap T(k) and
U Ap H(k) also be matrix
U Ap(k) multi-form.For simplicity, the matrix of indication in the following description
U Ap(k) and
V Ut(k) also refer to their various other forms.Matrix
U Ap(k) and
V Ut(k) be used for carrying out spatial manipulation by access point and user terminal respectively, and by their subscript sign.Eigenvector is also referred to as " control " vector usually.
User terminal can be estimated the downlink channel response of calibrating based on the MIMO pilot tone that access point sends.Then, user terminal can be estimated the downlink channel response of calibration
Carry out singular value decomposition (for k ∈ K), to obtain
Diagonal matrix
Matrix with left side eigenvector
V Ut *(k).This singular value decomposition can be given:
Wherein the cap " ^ " on each matrix represents that it is the estimation of actual matrix.
Similarly, access point can be estimated the uplink channel responses calibrated based on the MIMO pilot tone that user terminal sends.Then, access point can be estimated the uplink channel responses of calibration
Carry out singular value decomposition (for k ∈ K), to obtain
Diagonal matrix
Matrix with left side eigenvector
U Ap *(k).This singular value decomposition can be given:
One (N
Ut* N
Ut) matrix
F Ut(k) can be defined as:
When activity, user terminal is estimated the downlink channel calibrated continuously
And
The matrix of left side eigenvector
The latter is used for upgrading matrix
F Ut(k).
User terminal uses matrix
F Ut(k) carry out spatial manipulation for wave beam control and space multiplexing mode.For space multiplexing mode, the transmission of each subband vector
x Up(k) can be expressed as:
x up(k)＝
F ut(k)
s up(k)，k∈K， (42)
Wherein
s Up(k) be a data vector, it has will be at the N of subband k
sThe N that sends on the individual eigenmodes
sIndividual code element;
F Ut(k) in the replacement formula (15)
V(k), for simplicity, in formula (42), omitted for realize the channel counter-rotating by
G(k) the signal convergent-divergent that carries out;
x Up(k) be the transmission vector of the up link of subband k.
At the access point place, the reception of ul transmissions vector
r Up(k) can be expressed as:
Wherein
r Up(k) be the reception vector of up link subband k; And
n Up(k) be the Additive White Gaussian Noise (AWGN) of subband k.
Formula (43) uses following relational expression:
With
Shown in formula (43), at the access point place, the ul transmissions that receives by
Carry out conversion, the latter is
The matrix of left side eigenvector
Diagonal matrix with the singular value composition
Convergent-divergent.
User terminal uses matrix
F Ut(k) send a controlled benchmark in up link.Controlled benchmark is the pilot transmission on a broadband eigenmodes using wave beam control or beam forming, and the below describes in detail.At the access point place, the controlled benchmark of the up link that receives (when not having noise) is approximately
Like this, access point can draw unitary matrix based on the controlled benchmark that user terminal sends
And diagonal matrix
Estimation.Can draw with various estimation techniques the estimation of unitary matrix and diagonal matrix.
In one embodiment, in order to draw
Estimation, for the subband k of broadband eigenmodes m, the reception of controlled benchmark vector
r m(k) at first with the complex conjugate p that is the pilot tone OFDM code element that sends of controlled benchmark
*(k) multiply each other.The below describes the generation of controlled benchmark and pilot tone OFDM code element in detail.For each broadband eigenmodes, its result is in a plurality of controlled reference symbol upper integrals that receive, to draw
Estimation,
Broadband eigenmodes m
Through the left side of convergent-divergent eigenvector.Because eigenvector has unit power, therefore can estimate based on the received power of controlled benchmark
In singular value (or σ
m(k)), the received power of controlled benchmark can be measured for each subband of each broadband eigenmodes.
In another embodiment, come based on the reception of controlled benchmark vectorial with the MMSE technology
r m(k) draw
Estimation.
Controlled benchmark can be sent out in arbitrary given code-element period for a broadband eigenmodes, and is used for again drawing for each subband of this broadband eigenmodes the estimation of an eigenvector.Like this, receive the estimation that draws an eigenvector in the unitary matrix in the given code-element period of function in office.Because the estimation that in different code-element periods, draws a plurality of eigenvectors of unitary matrix, and because the noise in the transfer path and other degradation source, the eigenvector of therefore estimating for unitary matrix may be non-orthogonal.If estimated eigenvector is then used in the spatial manipulation of transfer of data on other link, then any error of the orthogonality of these estimated eigenvectors all can cause the cross-talk between eigenmodes, and this can make performance degradation.
In one embodiment, the eigenvector of estimating for each unitary matrix is forced orthogonal.The quadrature of eigenvector can be realized with various technology, such as QR Factorization, least mean-square error calculating, polarization decomposing etc.The QR Factorization is a matrix
M T(having non-orthogonal row) resolves into an orthogonal matrix
Q FWith a upper triangular matrix
R FMatrix
Q FFor
M TRow form the quadrature basis.
R FDiagonal element exist
Q FProvide on the direction of respective column
M TThe length of the component of each row.Matrix
Q FCan be used for the spatial manipulation on the down link.Matrix
Q FWith
R FCan be used for deriving the matched filter matrix that strengthens for up link.The QR Factorization can be carried out by the whole bag of tricks, comprises Gram-Schmidt process, householder transformation etc.
Also can be with other technology of estimating unitary matrix and diagonal matrix based on controlled benchmark, this is within the scope of the invention.
Therefore, access point can be estimated based on the controlled benchmark that user terminal sends
With
Both, and need not right
Carry out singular value decomposition.
Standardization matched filter matrix from the ul transmissions of user terminal
M Ap(k) can be expressed as:
The access point place can be expressed as for the matched filtering of ul transmissions:
Wherein
Up(k) be the modulation symbol vector that is sent by user terminal for space multiplexing mode
s Up(k) estimation.For the wave beam control model, only use matrix
M Ap(k) delegation comes to provide a symbol estimation for the used eigenmodes of transfer of data
(k).
2. down link spatial manipulation
For down link, access point uses (a N
Ap* N
Ap) matrix
F Ap(k) carry out spatial manipulation.This matrix can be expressed as:
Correction matrix
Derive and between alignment epoch, be sent back to access point by user terminal.Matrix
Can draw at the controlled benchmark that up link sends based on user terminal.
For space multiplexing mode, the transmission of the down link of each data subband vector
x Dn(k) can be expressed as:
x dn(k)＝
F ap(k)
s dn(k)，k∈K，(47)
Wherein
x Dn(k) be to send vector,
s Dn(k) be the data vector of down link, omit equally for simplicity by
G(k) the signal convergent-divergent for realizing that the channel counter-rotating is carried out.
At the user terminal place, the reception of downlink transmission vector
r Dn(k) can be expressed as:
Shown in formula (48), at the user terminal place, the downlink transmission warp that receives
Conversion,
Be
The matrix of left side eigenvector
Diagonal matrix with the singular value composition
Come convergent-divergent.
As mentioned above, estimate by the downlink channel response to calibration
Carry out singular value decomposition, user terminal can be derived diagonal matrix
Matrix with left side eigenvector
So the matched filtering that the user terminal place is downlink transmission to carry out can be expressed as:
3. the spatial manipulation of access point and user terminal
Because reciprocal channel and the calibration of TDD system, so the spatial manipulation at access point and user terminal place is all simplified.Access point summed up by table 32 and the user terminal place is the spatial manipulation that data input and data output carries out.
Table 32
The spatial manipulation of data receiver is also referred to as matched filtering.
Since the existence of reciprocal channel, therefore
It is user terminal
The right eigenvector of (be used for send) and
Both matrixes of left side eigenvector of (being used for receiving).Similarly,
It is access point
The right eigenvector of (be used for send) and
Both matrixes of left side eigenvector of (being used for receiving).Singular value decomposition need to be the downlink channel response estimation of calibration by user terminal only
Carry out, to draw
With
Access point can be derived based on the controlled benchmark that user terminal sends
With
And need not uplink channel responses is estimated
Carry out singular value decomposition.Access point and user terminal may be because for deriving
And used different means therefore to have multi-form matrix
In addition, access point is based on the matrix of controlled benchmark derivation
The matrix general and user terminal is derived with singular value decomposition
Different.For simplicity, in above-mentioned derivation, do not demonstrate these differences.
4. wave beam control
For specific channel condition, it is better only sending data a broadband eigenmodes, and this broadband eigenmodes generally is best or main broadband eigenmodes.This situation may be: the reception SNR of all other broadband eigenmodes is enough poor, thereby available transmitted power can realize improved performance by using all in main broadband eigenmodes.
Transfer of data on broadband eigenmodes can be controlled to realize with beam forming or wave beam.For beam forming, generally use the eigenvector of main broadband eigenmodes
Or
(namely after ordering,
Or
First row) modulated symbol is carried out spatial manipulation, k ∈ K wherein.For wave beam control, generally use one group of " standardized " (or saturated) eigenvector of main broadband eigenmodes
Or
Modulated symbol is carried out spatial manipulation, wherein k ∈ K.For clear, the wave beam control of up link is described below.
For up link, each eigenvector of main broadband eigenmodes
Element different sizes may be arranged, k ∈ K wherein.Like this, each subband also different sizes may be arranged through preregulated code element, described through preregulated code element by the eigenvector of the modulated symbol of subband k and subband k
Element multiply each other and draw.Thereby the transmission vector of every antenna all may have different sizes, described each send vector comprise a given transmitting antenna the total data subband through preregulated code element.If the transmitted power of every transmit antennas is restricted (for example because the restriction of power amplifier), then beam forming uses the gross power that every antenna can be used by halves.
The eigenvector of main broadband eigenmodes is only used in wave beam control
Phase information, k ∈ K, and each eigenvector carried out standardization is so that all elements in the eigenvector all has equal size.The standardization eigenvector of subband k
Can be expressed as:
Wherein A is a constant (for example A=1); And
θ
i(k) be the phase place of the subband k of antenna i, provide as follows:
Shown in formula (52), vector
In the phase place of each element from eigenvector
Respective element in to draw (be θ
i(k) from
Draw, wherein
5. uplink beam control
The spatial manipulation that user terminal carries out for wave beam control in up link can be expressed as:
Wherein
s Up(k) be the modulated symbol that will send at subband k; And
Shown in formula (53), the standardization control of each subband vector
N
UtIndividual element may have equal size but different phase places may be arranged.
The access point place is that the ul transmissions that wave beam control receives can be expressed as:
Wherein
For wave beam control, the reception vector of the up link of subband k.
Use the capable vector of matched filter of the ul transmissions of wave beam control
Can be expressed as:
The matched filter vector
Can draw as described below.The spatial manipulation (being matched filtering) that the access point place carries out for the receiving uplink transmission of using wave beam control can be expressed as:
Wherein
(namely
Be
Inner product with its conjugate transpose),
6. downlink beamforming control
Access point can be expressed as in the spatial manipulation that down link carries out for wave beam control:
Wherein
Be the standardization eigenvector of subband k, it is based on the eigenvector of main broadband eigenmodes
And generate, as above described for up link.
Use the capable vector of matched filter of the downlink transmission of wave beam control
Can be expressed as:
The spatial manipulation that the user terminal place carries out the downlink transmission that receives (being matched filtering) can be expressed as:
Wherein
(namely
Be
Inner product with its conjugate transpose).
7. the spatial manipulation of carrying out with the channel counter-rotating
For up link, the transmission of space multiplexing mode vector
x Up(k) can be exported as by user terminal:
Wherein
G(k) be the diagonal matrix of the gain of above-mentioned channel counter-rotating.Formula (60) is similar to formula (15), except using
Replace
V(k) in addition.
Element be provided for multiplier 952 in the beam-shaper 950 of Fig. 9 B.
For up link, the transmission of wave beam control model vector
Can be exported as by user terminal:
Wherein
Be a vector, it has four elements to have identical size, but phase place is based on the eigenvector of main eigenmodes
And draw.Vector
Can be similar to top such derivation the described in formula (16) and (17).Gain
Realization channel counter-rotating, and above can being similar to such derivation the described in the formula (18) to (20), except being formula (20) use
In addition.
Element be provided for multiplier 1052 in the wave beam control unit 1050 of Figure 10 B.
For down link, the transmission of space multiplexing mode vector
x Dn(k) can be exported as by access point:
Formula (62) is similar to formula (15), except replacing
V(k) use
In addition.
Element can be provided for multiplier 952 in the beam-shaper among Fig. 9 B 950.
For down link, the transmission of wave beam control model vector
Can be exported as by access point:
Wherein
Be a vector, it has four elements, and they have equal size, but their phase place is based on main eigenmodes
Draw.Gain
Realized the channel counter-rotating, and can be with top such derivation the described in the formula (18) to (20), except being formula (20) use
In addition.
Element be provided for multiplier 1052 in Figure 10 B medium wave beam control unit processed 1050.
VIII. pilot configuration
For the MIMO wlan system provides a pilot configuration, access point and user terminal can be carried out regularly and frequency acquisition, channel estimating and correct other required function of System Operation.Table 33 is listed four class pilot tones and their Short Description of an exemplary pilot structure.
Table 33-pilot type
| Pilot type | Describe |
| Beacon pilot frequency | Send and be used for the pilot tone of timing and frequency acquisition from all transmitting antennas. |
| The MIMO pilot tone | Send and be used for the pilot tone of channel estimating from all transmitting antennas with different orthogonal codes. |
| Controlled benchmark or controlled pilot tone | Send and be used for the pilot tone of channel estimating and possible speed control in the specific eigenmodes of the mimo channel of a specific user terminal. |
| Carrier pilot | Be used for carrier signal is carried out the pilot tone of Phase Tracking. |
Controlled benchmark and controlled pilot tone are synonyms.
In one embodiment, pilot configuration comprises: the carrier pilot that (1) sends for down link-beacon pilot frequency, MIMO pilot tone, controlled benchmark and access point, and (2) are for up link-MIMO pilot tone, controlled benchmark and the carrier signal that sent by user terminal.
Downlink beacon pilot tone and MIMO pilot tone are sending (shown in Fig. 5 A) at BCH in each tdd frame.User terminal can use beacon pilot frequency to carry out timing and frequency acquisition and Doppler's estimation.User terminal can come with the MIMO pilot tone: (1) draws the estimation of downlink mimo channel, (2) for ul transmissions derives controlled vector (if supporting wave beam control or space multiplexing mode), and (3) are downlink transmission induced matching filter.The controlled benchmark of down link can be used for carrying out channel estimating by specific user terminal.
The controlled benchmark of up link is sent by each active user terminals of supporting wave beam control or space multiplexing mode, and can be used for by access point: (1) derives dominant vector for downlink transmission, and (2) are ul transmissions induced matching filter.Usually, controlled benchmark is only sent by the user terminal of supporting wave beam control and/or space multiplexing mode.Benchmark sends object, and no matter whether it is correctly controlled (for example because poor channel estimating).Namely, because gating matrix is the diagonal angle, so benchmark is also by every transmit antennas quadrature that becomes.
If user terminal is calibrated, then it can use vector
(for k ∈ K) main eigenmodes on RACH sends a controlled benchmark, wherein
For main eigenmodes
Row.If user terminal is not calibrated, then it can be with vectorial
(for k ∈ K) sends a pilot tone at RACH.The vector of each subband
v Ut, p(k) comprise N
UtIndividual STOCHASTIC CONTROL coefficient, their phase theta
i(k) may select according to-pseudo-random process, wherein i ∈ 1,2 ... N
Ut.Owing to only having N
UtRelative phase between individual control coefrficient just has relation, and therefore can be made as zero to the phase place of the first control coefrficient (is θ
1(k)=0).Other N
UtThe phase place of-1 control coefrficient may change when each access attempts, so that each control coefrficient is with 360 °/N
θ iThe interval covered whole 360 degree, N wherein
θ iN
UtFunction.When before calibration, in beam modes, using RACH, when each RACH attempts to dominant vector
v Ut, p(k) N
UtThe phase perturbation of individual element makes user terminal not make the dominant vector of damaging for all access attempts.Can send MIMO for the user terminal of not supporting wave beam control and/or space multiplexing mode, or send MIMO by these user terminals.
Directly with before access point is communicated by letter, access point is not known the channel of arbitrary user terminal at user terminal.When the user wished to send data, it at first estimated channel based on the MIMO pilot tone that access point sends.()
Dominant vector
To estimate through the uplink channel responses of calibration
The matrix of the right eigenvector
First row, wherein
Be
I row.Above supposition
In singular value and
Row with above-mentioned arranged sequentially.
The second code element of the controlled benchmark that user terminal sends in the leader of RACH comprises the data rate indicator (DRI) of RACH PDU.As shown in Table 15, by DRI being mapped to a specific QPSK code element s
DriDRI is embedded in the second controlled reference symbol, then, s
DriCode element multiplies each other with pilot frequency code element p (k) before spatial manipulation.The second code element of the controlled benchmark of RACH can be expressed as:
Shown in formula (64) and (65), the eigenvector of main eigenmodes only
The controlled benchmark that just is used for RACH.
The code element of the controlled benchmark that user terminal sends in the leader of RCH can be expressed as:
Wherein
x Up, sr, m(m) be the transmission vector of the subband k of broadband eigenmodes m; And
The code element of the controlled benchmark that access point sends in the leader of RCH can be expressed as:
Wherein
x Dn, sr, m(m) be the transmission vector of the subband k of broadband eigenmodes m; And
Dominant vector
To estimate through the downlink channel response of calibration
The right eigenvector matrix
M row, wherein
Controlled benchmark can send in every way.In one embodiment, one or more eigenvectors are used for the controlled benchmark of each tdd frame, and depend on the duration of controlled benchmark, and the latter is represented by the FCH/RCH leader type field in the FCCH information element.Table 36 is listed for an exemplary design, for the employed eigenmodes of leader of RCH and the RCH of various leader sizes.
Table 36
| Type | The leader size | Employed |
| 0 | 0 OFDM code element | Without |
| 1 | 1 OFDM code element | Eigenmodes m, wherein m= |
| 2 | 4 OFDM code elements | Whole 4 eigenmodes circulations in |
| 3 | 8 OFDM code elements | In leader twice of whole 4 eigenmodes cocycle |
Shown in table 36, when guide's sequence size is 4 or 8 OFDM code elements, for whole four eigenmodes in the single tdd frame send controlled benchmark.User terminal is that the controlled benchmark that n OFDM code element sends in the leader of RCH can be expressed as:
Wherein L is the leader size, and namely for type 2, L=4 is for type 3, L=8.
Similarly, access point is that the controlled benchmark that n OFDM code element sends in the leader of FCH can be expressed as:
Shown in formula (68) and (69), circulate through four eigenmodes in each 4-code-element period by (the n mod 4) computing of dominant vector.This scheme can when channel changes more fast, use and/or when obtaining good channels for correct system action need and estimate at an early application that connects.
In another embodiment, a broadband eigenmodes for each tdd frame sends controlled benchmark.For example, in four tdd frames, can circulate through the controlled benchmark of four broadband eigenmodes.For example, user terminal can be respectively the first, second, third and the 4th tdd frame and use dominant vector
With
The specific dominant vector that uses can be specified by 2 LSB of frame counter value in the BCH message.This scheme can be used shorter leader part in PDU, but the time period that may require to grow obtains the good estimation of channel.
For above-mentioned two embodiment, can send controlled benchmark in used whole four eigenmodes of transfer of data, be less than four eigenmodes (for example because untapped eigenmodes is very poor and abandon by water filling) even used at present.Controlled benchmark at present do not use transmission on the eigenmodes to make to receive function to determine when eigenmodes is improved to can be selected.
B. the controlled benchmark of wave beam control
For the wave beam control model, the spatial manipulation of transmitting terminal is carried out with one group of standardization eigenvector of main broadband eigenmodes.Overall transfer function with standardization eigenvector be different from have the nonstandardized technique eigenvector overall transfer function (namely
)。Then, the controlled benchmark that generates with one group of standardization eigenvector of whole subbands can be sent by transmitter, and is used for these subband induced matching filter vector into the wave beam control model by receiver.
For up link, the controlled benchmark of wave beam control model can be expressed as:
At the access point place, the controlled benchmark of the receiving uplink of wave beam control model can be expressed as:
In order to obtain the capable vector of matched filter for the ul transmissions of using wave beam control
The reception vector of controlled benchmark
At first with p
*(k) multiply each other.So on the controlled reference symbol of a plurality of receptions to integration as a result to form
Estimation.So vector
It is exactly the conjugate transpose of this estimation.
Be operated in wave beam control model lower time, user terminal can send a plurality of code elements of controlled benchmark, for example Application standard eigenvector
One or more code elements, use the eigenvector of main broadband eigenmodes
One or more code elements and the one or more code elements that may use the eigenvector of other broadband eigenmodes.With
The controlled reference symbol that generates can be used for the induced matching filter vector by access point
With
The controlled reference symbol that generates can be used to obtain
Then be used for deriving on the down link wave beam and control employed standardization eigenvector
Eigenvector with other eigenmodes
Arrive
The controlled reference symbol that generates can be used for drawing by access point
Arrive
And the singular value of these other eigenmodes.This information then is used for being defined as transfer of data usage space multiplexer mode or wave beam control model by access point.
For down link, user terminal can be estimated based on the downlink channel response through calibration
Be wave beam control model induced matching filter vector
Particularly, user terminal from
Singular value decomposition draw
And can derive the standardization eigenvector
Then, user terminal can
With
Multiply by mutually and draw
Then based on
Derive
Perhaps, controlled benchmark can be by access point Application standard eigenvector
Send, this controlled benchmark can be processed to draw by user terminal in the above described manner
4. carrier pilot-up link
OFDM sub band structure described here comprises that index is four pilot subbands of-21 ,-7,7 and 21.In one embodiment, a carrier pilot is not that four pilot subbands of a leader part send in whole OFDM code elements.Carrier pilot can be used for following the tracks of the phase place that the drift owing to transmitter and receiver place oscillator causes by receiver to be changed.This may provide improved data demodulates performance.
Carrier pilot comprises four pilot frequency sequence P
C1(n), P
C2(n), P
C3(n) and P
C4(n), they are sent out four pilot subbands.Pilot frequency sequence can be defined as:
P
c1(n)＝P
c2(n)＝P
c3(n)＝-P
c4(n)，n＝{1，2，...27}，(72)
Wherein n is the index of OFDM code-element period.
Pilot frequency sequence can define based on various data sequences.In one embodiment, pilot frequency sequence P
C1(n) based on multinomial G (x)=x
7+ x
4+ x generates, wherein initial condition be set as complete one, the following signal value that is mapped as of output bit: 1
-1 and 0
1.So, for n={1,2 ... 127}, pilot frequency sequence P
C1(n) can be expressed as:
P
c1(n)＝{1，1，1，1，-1，-1，-1，1，-1，-1，-1，-1，1，1，-1，1，-1，-1，1，1，-1，1，1，-1，1，1，1，1，1，1，-1，1，
1，1，-1，1，1，-1，-1，1，1，1，-1，1，-1，-1，-1，1，-1，1，-1，-1，1，-1，-1，1，1，1，1，1，-1，-1，1，1，
-1，-1，1，-1，1，-1，1，1，-1，-1，-1，1，1，-1，-1，-1，-1，1，-1，-1，1，-1，1，1，1，1，-1，1，-1，1，-1，1，
-1，-1，-1，-1，-1，1，-1，1，1，-1，1，-1，1，1，1，-1，-1，1，-1，-1，-1，1，1，1，-1，-1，-1，-1，-1，-1，-1}.
Pilot frequency sequence P
C1(n) value in " 1 " and " 1 " can be with a specific modulation to pilot frequency code elements.For example, by using BPSK, " 1 " is mapped as " 1+j ", and " 1 " is mapped as " (1+j) ".If have more than 127 OFDM code elements, then repeat pilot frequency sequence, so that for n＞127, P
C1(n)=P
C1(nmod127)
In one embodiment, be four pilot frequency sequences of each transmission channel replacement.Like this, on down link, being an OFDM code element replacement pilot frequency sequence of BCH message, is that an OFDM code element of FCCH message is reset again, and the OFDM code element replacement that sends for FCH is upper.In another embodiment, pilot frequency sequence is reset at the place that begins of each tdd frame, and repeats as required.For this embodiment, pilot frequency sequence can be stopped during the leader part of BCH and RCH.
Under diversity mode, shown in table 29, four pilot frequency sequences are mapped as four subband/antennas pair.Particularly, P
C1(n) be used for the subband-21 of antenna 1, P
C2(n) be used for the subband-7 of antenna 2, P
C3(n) be used for the subband 7 of antenna 3, P
C4(n) be used for the subband 21 of antenna 4.Then each pilot frequency sequence is sent out at relevant subband and antenna.
Under space multiplexing mode, four pilot frequency sequences are sent out in the main eigenmodes of their corresponding subbands.The spatial manipulation of carrier pilot code element is similar to the processing of carrying out into modulated symbol, as mentioned above.Under the wave beam control model, four pilot frequency sequences use wave beam to be controlled on their corresponding subbands and are sent out.The wave beam control of carrier pilot code element also is similar to the processing of carrying out into modulated symbol.
The above has described a specific pilot configuration for the MIMO wlan system.Also can be for this system use other pilot configuration, this is within the scope of the invention.
IX. system's operation
Figure 12 A illustrates a specific embodiments of the state diagram 1200 of user terminal operations.This state diagram comprises one of four states-initial (Init) state 1210, dormancy (Dormant) state 1220, access (Access) state 1230 and is connected (Connected) state 1240.Each state 1210,1220,1230 and 1240 is associated with a plurality of sub-states (not shown in Figure 12 A for simplicity).
In initial condition, user terminal capture systems frequency and timing, and obtain the upper system parameters that sends of BCH.In initial condition, user terminal can be carried out following functions:
● system determines-user terminal determines which carrier frequency to come capture systems with.
● frequency/timing acquisition-user terminal is caught beacon pilot frequency and is correspondingly regulated its frequency and timing.
● parameter catches-system parameters of user terminal processes BCH to obtain to be associated with the access point of receiving downlink signal therefrom.
After finishing the required function of initial condition, user terminal changes resting state into.
In resting state, user terminal periodically monitor the system parameters that whether has among the BCH after the renewal, to the indication of the paging that sends on the down link and broadcast, etc.Do not distribute any Radio Resource to user terminal under this state.In resting state, user terminal can be carried out following functions:
If ● the registration guaranteed, user terminal just enters access state according to registration request.
● if the calibration of emittor/receiver guaranteed, user terminal just enters according to calibration request and accesses terminal.
● user terminal monitors whether BCH has the upper paging that sends of couple FCH and the indication of broadcast.
● if user terminal has the data that will send in up link, and it just enters access state according to resource request.
● user terminal is carried out such as the update system parameter and is followed the tracks of the such maintenance process of channel.
● user terminal can enter the operator scheme of time-division slot with conserver power source, if this pattern is supported by user terminal.
If user terminal is all expected Radio Resource from access point for any task, it just changes into and accesses terminal.For example, user terminal can change access state in response to the paging that sends in the BCH message or DST designator, is used for registration or request calibration, perhaps the special-purpose resource of request.
In access state, user terminal is in the process of connecting system.User terminal can send SMS message and/or to the request of FCH/RCH resource with RAHC.Operation on the RACH is following to be described in further detail.If user terminal is access in a release, it just transforms back into resting state.If user terminal is assigned to the resource of down link and/or up link, it just changes connection status into.
In connection status, user terminal is assigned to the FCH/RCH resource, although be not necessary for each tdd frame.User terminal can use actively the resource of distributing or can be idle (still keeping connecting) in connection status.User terminal remains under the connection status, until it be access in a release or it in a specific timeout period, do not have overtime after movable till, it transforms back into resting state in this situation.
In dormancy, access or connection status lower time, if if user terminal is closed power supply or connects to be lost, user terminal just transforms back into initial condition.
Figure 12 B illustrates a specific embodiments of the state diagram of connection status 1240.In this embodiment, connection status comprises the sub-state 1260 of three sub-states-set up, opens sub-state 1270 and idle sub-state 1280.User terminal enters the sub-state of setting up after FCCH receives distribution.
In setting up sub-state, user terminal is in the process of setting up connection, not yet swap data.Connect set up can comprise to access point, speed determine, the channel estimating of service negotiation etc.Enter set up sub-state after, user terminal arranges a timer in a specific time quantum.If timer expired before user terminal leaves this sub-state, it just changes resting state into.User terminal changes the sub-state of opening into after setting up finishing to connect.
In opening sub-state, user terminal and access point be swap data on down link and/or up link.In the time of in opening sub-state, user terminal monitors whether BCH has the indication of system parameters and paging/broadcast.If be correctly decoded BCH message in the tdd frame of a specific quantity, then user terminal transforms back into initial condition.
User terminal monitors also whether FCCH has channel allocation, speed control, RCH timing controlled and power control information.User terminal is estimated the SNR that receives with BCH beacon pilot frequency and FCH leader, and determines the maximum rate that can reliably keep on FCH.
The FCH of the user terminal of each tdd frame and RCH distribution are provided by the information element among the FCCH PDU that sends in current (perhaps may be previous) tdd frame.For arbitrary given tdd frame, for the distributing user terminal not of the transfer of data on FCH and/or the RCH.For wherein not being each tdd frame of data transmission scheduling user terminal, it does not receive FCH PDU at down link, and does not send in up link.
For each tdd frame of scheduling user terminal wherein, the transfer of data on down link and/or the up link uses FCCH to distribute speed, transmission mode and the RCH timing slip (for up link) of expression in (namely being addressed to the FCCH information element of user terminal) to carry out.User terminal receives the FCH PDU that sends to it, and it is carried out the demodulation code.User terminal also sends RCH PDU, and it comprises leader and RCH data rate indicator.The rate control information that user terminal comprises in distributing according to FCCH is regulated the upper speed of using of RCH.If be the control of ul transmissions applied power, then the user regulates its transmitted power based on the power control command that comprises among the FCCH.Exchanges data can happen suddenly, and user terminal enters idle sub-state in this situation when not having data commutative.User terminal enters idle sub-state according to the indication of access point.If access point is not distributed to user terminal to FCH or RCH in the tdd frame of a specific quantity, then user terminal transforms back into resting state and keeps its MAC ID.
In idle sub-state, up link and down link all are idle.On either direction, do not send data.Yet link is kept with controlled benchmark and control message.Under this sub-state, access point is at RCH and may periodically distribute to user terminal (unnecessary while) to idle PDU on the FCH.Perhaps, user terminal can remain under the connection status indefinitely, as long as access point periodically distributes idle PDU to keep this link on FCH and RCH.
In idle sub-state lower time, user terminal monitors BCH.If BCH message is not correctly decoded in the tdd frame of a specific quantity, then user terminal just transforms back into initial condition.User terminal monitors also whether FCCH has channel allocation, speed control, RCH timing controlled and power control information.User terminal can also estimate to receive the maximum rate that SNR and definite FCH support.User terminal sends idle PDU at RCH (when being assigned with), and if its RCH request bit of having data to send just to arrange among the idle PDU.If access point is not distributed to user terminal to FCH or RCH in the tdd frame of a specific quantity, user terminal just transforms back into resting state, and keeps its MAC ID.
Enter three sub-states any one after, overtime timer can be set as a particular value.If there is not activity in the time of in sub-state, then this timer countdown.Set up, in activity or the idle sub-state time, if the expiration of overtime timer, terminal can transform back into resting state, loses if connect, terminal can transform back into initial condition.In activity or idle sub-state lower time, be released if connect, terminal also can transform back into resting state.
Figure 12 A and 12B illustrate a specific embodiment of the state diagram that can be used for user terminal.Also can be for system definition have less, additional and/or different states and various other state diagrams of sub-state, this is within the scope of the invention.
X. at random access
In one embodiment, adopt a kind of random access scheme to make user terminal can access the MIMO wlan system.In one embodiment, random access scheme is based on the Aloha scheme of a time-division slot, and user terminal sends in order to can access this system in the random RACH time slot of selecting whereby.User terminal can send a plurality of transmission at RACH, until access licensed or reached maximum access attempts number of times.Can change the parameters of each RACH transmission to improve the probability of success, as described below.
Figure 13 has illustrated the timeline of RACH, and it is divided into the RACH time slot.In each tdd frame and the RACH time slot duration can with the RACH number of time slot be configurable parameter.Can use maximum 32 RACH time slots in each tdd frame.Protection interval between the BCH PDU of the ending of a upper RACH time slot and next tdd frame begins also is configurable parameter.Three parameters of this of RACH can change along with the change of frame, and indicated by RACH length field, RACH time slot size field and the RACH protection interval field of BCH message.
When user terminal was wished connecting system, it is the system parameters of treatments B CH to obtain to be correlated with at first.Then, user terminal sends a RACH PDU at RACH.This RACH PDU comprises a RACH message, and it comprises access point for processing from the required information of the access request of user terminal.For example, RACH message comprises the MAC ID that user terminal is assigned to, and it makes access point energy identifying subscriber terminal.Registration MAC ID (being specific MAC ID value) can keep for unregistered user terminal.In this situation, the long ID of user terminal can be included in the load field of RACH message together with registration MAC ID.
As described below, RCH PDU can be sent out with one of four speed, and is listed such as table 15.Selected speed is embedded in the leader of RACH PDU (shown in Fig. 5 C).RACH PDU also has variable- length 1,2,4 or 8 OFDM code elements (also listing such as table 15), and this length represents in the message duration of RACH message field.
In order to send RACH PDU, user terminal is at first determined the RACH number of time slot (i.e. " available " RACH number of time slot) that can be used for transmitting.This determines to make based on following: available RACH number of time slot in (1) current tdd frame, the duration of (2) each RACH time slot, (3) protection interval, and the length of (4) the RACH PDU that will send.RACH PDU can not extend beyond the ending of the RACH segmentation of tdd frame.Like this, if RACH PDU adds that than a RACH time slot protection interval is long, then this PDU can not be sent out at one or more after a while available RACH time slots.Based on above-named factor, the RACH timeslot number that can be used for sending RACH PDU may lack than the number of available RACH time slot.The RACH segmentation comprises a protection interval, and the latter is used for preventing that the ul transmissions from user terminal from can disturb with next BCH segmentation, and this is possible for the user terminal that does not compensate its round-trip delay.
Then, user terminal select randomly can with one of RACH time slot send RACH PDU.Then, user terminal begins to send RACH PDU from selected RACH time slot.If user terminal is known the round-trip delay of access point, then it can regularly remedy this delay by correspondingly regulating it.
When access point received a RACH PDU, it checked this message with receiving the CRC that comprises in the RACH message.If the CRC failure, access point just abandons this RACH message.If CRC passes through, access point just arranges the RACH acknowledgement bit on the BCH in follow-up tdd frame, and sends RACH affirmation at FCCH in 2 tdd frames.Acknowledgement bit is set and may has delay between the FCCH transmission is confirmed at BCH, it is used for remedying dispatch delay etc.For example, if access point receives message at RACH, it can arrange acknowledgement bit at BCH, and has delayed response at FCCH.Acknowledgement bit stops user terminal to carry out retry, and makes fast retry of unsuccessful user terminal, except at busy RACH in the cycle.
If user terminal is being carried out registration, it just uses registration MAC ID (for example 0x0001).Access point responds by sending a MAC ID assignment messages at FCH.All other RACH transport-type comprises the user terminal MAC ID that system distributes.Access point is distributed to user terminal by use MAC ID sends affirmation at FCCH, thereby has clearly confirmed the RACH message that all correctly receive.
After user terminal sent RACH PDU, it monitored that BCH and FCCH are to determine whether its RACH PDU has been access in a reception and processing.User terminal monitors that BCH is to determine whether to be provided with the RACH acknowledgement bit in the BCH message.If this bit is established, this affirmation that shows this and/or other user terminal sends at FCCH, so user terminal is further processed FCCH to obtain to comprise IE type 3 information elements of affirmation.Otherwise if the RACH acknowledgement bit is not established, user terminal just continues to monitor BCH or continue its access procedure on RACH.
If user terminal receives an affirmation at FCCH in the tdd frame of a specific quantity after sending RACH PDU, it just continues the access procedure on the RACH.In this situation, user terminal can suppose that access point does not correctly receive RACH PDU.User terminal is kept a counter access number of attempt is counted.This counter the first time access attempts be initialized as zero, then increase one for each access request subsequently.If Counter Value reaches maximum attempts, user terminal just stops access procedure.
For each follow-up access attempts, user terminal is at first determined the parameters of this access attempts, comprise that (1) is sending the time quantum that will wait for before the RACH PDU, the RACH time slot that use for RACH PDU transmission (2), and the speed of (3) RACH PDU.For the time quantum of determining to wait for, the maximum time amount that the at first definite next time access attempts of user terminal will be waited for, this is called contention window (CW).In one embodiment, contention window (providing take tdd frame as unit) may the growth of index ground (be CW=2 for each access attempts
Access_attempt).Contention window also can be determined based on some other function (for example linear function) of access attempts number of times.Then the time quantum that random next access attempts of selection will be waited between zero-sum CW.User terminal can be waited for this time quantum before sending RACH PDU for next access attempts.
For next access attempts, if be not that a upper access attempts uses minimum speed limit, user terminal reduces the speed of RACH PDU.The initial rate of the first access attempts can be selected based on the reception SNR of the upper pilot tone that sends of BCH.Access point is failed correctly to receive RACH PDU and may be caused and fail to receive the confirmation.Like this, the speed of RACH PDU is lowered in next access attempts, to improve the correct probability that receives of access point.
After having waited for this random stand-by period of selecting, user terminal selects a RACH time slot to be used for the transmission of RACH PDU again at random.The selection of the RACH time slot of this access attempts can be carried out with the similar fashion of above-mentioned the first access attempts, except the RACH parameter (being RACH timeslot number, time slot duration and protection interval) of (in BCH message, transmitting) current tdd frame with current RACH PDU length is used.Then RACHPDU is sent out in the random RACH time slot of selecting.
Above-mentioned access procedure continues until following any point occurs: (1) user terminal receives an affirmation from access point, or (2) have reached the maximum number of attempt that allows.For each access attempts, can be chosen in as described above and send the time quantum that to wait for before the RACH PDU, RACH time slot that RACH PDU transmission will be used and the speed of RACH PDU.If receive the confirmation, user terminal just as indicated in confirming work (be that it is waited for when receiving quick affirmation in resting state, perhaps use FCH/RCH begins when receiving based on the affirmation that distributes).If reached the maximum access attempts number of times that allows, user terminal just transforms back into initial condition.
XI. speed, power and timing controlled
Down link on access point scheduled FCH and the RCH and ul transmissions, and further control the speed of all active user terminals.In addition, access point is in the transmitted power of up link adjusted specific activities user terminal.Various control loops be can keep and each active user terminals regulations speed, transmitted power and timing come to be.
1. fix and variable rate services
Access point can be supported the service of the fixing and variable bit rate on FCH and the RCH.The fixed rate service can be used for voice, video etc.Variable rate services can be used for grouped data (for example web browsing).
For the fixed rate service on the FCH/RCH, fixed rate is used for whole connection.The transmission of best achievement is used for FCH and RCH (namely not retransmitting).Access point is dispatched the FCH/RCH PDU of constant number in each fixed time interval, to satisfy the Qos requirement of service.According to postponing requirement, access point may need not each tdd frame and dispatch a FCH/RCH PDU.For the fixed rate service, realize power control at RCH rather than FCH.
For the variable rate services on the FCH/RCH, the employed speed of FCH/RCH can change along with channel condition.For some synchronous service (for example video, audio frequency), qos requirement can be utilized minimum-rate constraints.For these services, the scheduler at access point place is regulated FCH/RCH and is distributed, thereby constant rate of speed can be provided.For asynchronous data service (for example web-browsing, file transfer etc.), optimum efficiency transmits and has the re-transmission option.For these services, speed be channel condition the maximum that can reliably bear.Scheduling to the FCH/RCH PDU of user terminal generally is the function of their qos requirement.When not having data to send at downlink/uplink, send idle PDU to keep link at FCH/RCH.For variable rate services, realize the control of closed-loop power at FCH rather than RCH.
2. speed control
Speed control can be used for the variable rate services of FCH and the upper work of RCH, so that the channel condition that makes the speed of FCH/RCH be suitable for changing.The employed speed of FCH and RCH can be controlled independently.In addition, in space multiplexing mode, the speed of each broadband eigenmodes of each dedicated transmission channel can independently be controlled.Speed control is carried out based on the feedback that each active user terminals provides by access point.Scheduler schedules transfer of data in the access point, and the rate-allocation of definite active user terminals.
The maximum rate that can support on arbitrary link all is following function: the channel response matrix of (1) total data subchannel, and the viewed noise level of (2) receiver, the quality of (3) channel estimating, and may other factors.For the TDD system, channel for down link and up link can be considered to be reciprocal (carry out calibration with any difference that remedies access point and user terminal place after).Yet this reciprocal channel does not also mean that noise floor is identical with the user terminal place at access point.Therefore, for given user terminal, the speed on FCH and the RCH can be controlled independently.
The control of closed-loop speed can be used for the transfer of data on one or more space channels.The control of closed-loop speed can realize with one or more loops.Inner ring road is estimated channel condition and is that each used space channel of transfer of data is selected a suitable speed.Channel estimating and speed are selected and can be carried out as described above.Outer ring can be used for estimating the quality of the transfer of data that receives at each space channel, and regulates the operation of inner ring road.Data transmission quality can quantize with packet error rate (PER), decoder metric etc. or their combination.For example, outer ring can be regulated the SNR skew of each space channel in order to be this space channel realize target PER.If for space channel detects excessive packet error, it is that a space channel selects one than low rate that outer ring also can be indicated inner ring road.
Downlink rate control
Each active user terminals can be come estimating down-ward link channel based on the MIMO pilot tone that sends at BCH in each tdd frame.Access point also can send a controlled benchmark in sending to the FCH PDU of specific user terminal.By the MIMO pilot tone on the use BCH and/or the controlled benchmark on the FCH, user terminal can estimate to receive the maximum rate that can support on SNR and the definite FCH.If user terminal is operated under the space multiplexing mode, just can determine maximum rate for each broadband eigenmodes.Each user terminal can be in the FCH of RCH PDU rate indicator field be beamed back the maximum rate (for diversity mode) that maximum rate (for space multiplexing mode) that each broadband eigenmodes supports, maximum rate (for the wave beam control model) that main broadband eigenmodes is supported or mimo channel are supported to access point.These speed can be mapped as and receive SNR, and the latter then is used for carrying out above-mentioned the injecting process.Perhaps, user terminal can be beamed back sufficient information (for example receiving SNR) in order to make access point can determine the maximum rate that down link is supported.
For using determining to be based on and making from the feedback of user terminal of diversity, wave beam control or space multiplexing mode.Along with the separation between dominant vector improves, the number of the broadband eigenmodes of selecting also can increase.
Figure 14 A has illustrated the process for the speed of user terminal control downlink transmission.One BCH PDU sends in the first segmentation of each tdd frame, and comprises beacon and the MIMO pilot tone that can be used for estimating and following the tracks of by user terminal this channel.Controlled benchmark also can be sent out in the leader of the FCH PDU that sends to user terminal.User terminal is estimated this channel based on MIMO and/or controlled benchmark, and the maximum rate that can support of definite down link.If under space multiplexing mode, then being each broadband eigenmodes, user job supports a speed.Then, user terminal sends the rate indicator of FCH in the FCH rate indicator field of the RCH PDU that it sends to access point.
Scheduler can be dispatched downlink transmission in the follow-up tdd frame for the maximum rate of each active user terminals support with down link.The speed of user terminal and other channel allocation information reflect in the information element that FCCH sends.The speed of distributing to a user terminal can affect the scheduling of other user terminal.The user determines that the minimum delay between speed and the use thereof is about single tdd frame.
By using the Gram-Schmidt sequencer procedure, access point can directly be determined the maximum rate that FCH supports from the RCH leader exactly.So this can simplify speed control greatly.
Uplink rate control
Each user terminal sends a controlled benchmark at RACH during system access, and sends controlled benchmark at RCH after being assigned to the FCH/RCH resource.Access point can be that each broadband eigenmodes estimates to receive SNR based on the controlled benchmark on the RCH, and determines the maximum rate that each broadband eigenmodes is supported.At first, access point may not have good channel estimating in order to allow at the maximum rate place that each broadband eigenmodes is supported or near the reliable operation that carries out it.In order to improve reliability, the initial rate of the upper use of FCH/RCH can be significantly less than the maximum speed of supporting.Access point can be on a plurality of tdd frames to controlled benchmark integration in order to obtain improved channel estimating.Along with the raising of channel estimating, speed also can be enhanced.
Figure 14 B has illustrated the process of the speed that is used to user terminal control ul transmissions.When being uplink transmission scheduling, user terminal sends a RCH PDU, and it comprises that access point is used for determining the benchmark of the maximum rate on the up link.Then, scheduler can be dispatched uplink data transmission in the follow-up tdd frame for the maximum rate of each active user terminals support with up link.The speed of user terminal and other channel allocation information are reflected in the upper information element that sends of FCCH.Access point determines that the minimum delay between speed and the use thereof is about single tdd frame.
3. power control
For the fixed rate service, power control can be used for the ul transmissions (but not speed control) on the RCH.For the fixed rate service, speed is consulted when call setup, and keeps fixing during connecting.Some fixed rate services may require with limited mobility to be associated.Yet in one embodiment, control to resist the interference between user terminal for up link has realized power, but down link is not used power control.
One power control mechanism is used for controlling the up-link transmit power of each active user terminals, so that the SNR that the access point place receives is maintained at a rank that can realize the desired service quality.This rank is commonly referred to target and receives SNR, working point or set point.For mobile user terminal, propagation loss probably changes along with moving of user terminal.Power control mechanism is followed the tracks of the variation in the channel in order to remain near the set point receiving SNR.
Power control mechanism can be with two power control loop road realization-inner ring roads and outer ring.The transmitted power of inner loop adjustment user terminal is so that the reception SNR at access point place is maintained near the set point.Outer ring is regulated set point realizing other performance of a specific order, and performance measures quantification by specific FER (Floating Error Rate) (FER) (for example 1%FER), packet error rate (PER), BLER (block error rate) (BLER), message error rate (MER) or some.
Figure 15 has illustrated the operation of the internal power control of user terminal.After user terminal was assigned to FCH/RCH, access point was estimated the reception SNR on the RCH and it is compared with set point.The initial power that user terminal will use can determine when call setup, and generally near its maximum transmit power level.For each frame period, exceed a specific positive surplus δ if receive SNR, access point just can reduce a specified quantitative (for example 1dB) with its transmitted power in the FCCH information element indicating user terminal that sends to this user terminal.On the contrary, if receive SNR than the low surplus δ of threshold value, access point just can improve described specified quantitative with its transmitted power by indicating user terminal.If receive SNR in acceptable set point restriction, access point just can not ask the transmitted power of user terminal is changed.Up-link transmit power is given the initial transmission power level and adds all power adjustments sums that receive from access point.
The initial setting point of access point place use is set to realize other performance of a specific order.This set point is regulated by FER or the PER of outer ring based on RCH.For example, if on a special time period frame error/packet error does not occur, then set point can reduce the first amount (for example 0.1dB).If exceed mean F ER owing to one or more frame error/packet errors occurring, then set point can improve the second amount (for example 1dB).Employed power control design is specific for system for set point, hysteresis margin and outer ring operation.
4. timing controlled
Timing controlled is preferably used in the frame structure based on TDD, and wherein down link and up link are shared identical frequency band in the mode of time division duplex.Therefore user terminal can spread in the system, and is associated from different propagation delays to access point.In order to make the efficient on the up link maximum, can regulate timing from the RCH of each user terminal and the ul transmissions on the RACH to remedy its propagation delay.So this can guarantee to arrive the access point place from the ul transmissions of different user terminals in a special time window, and can be not interfering with each other on up link, and is perhaps like this for downlink transmission.
Figure 16 has illustrated the process of the uplink timing that is used for the adjusting user terminal.At first, user terminal sends a RACH PDU so that can connecting system in up link.Access point is derived the initial estimation of the round-trip delay (TDD) that is associated with user terminal.Round-trip delay can be based on following estimation: (1) access point is used for determining the sliding correlation detector of transmission starting point, and the time slot ID that comprises among the RACH PDU that sends of (2) user terminal.Then, access point is estimated as user terminal based on Initial R TD and calculates an initial timing lead.The initial timing lead was sent to user terminal at it before the transmission on the RCH.The initial timing lead can be sent out in the message on FCH, be sent out in a field of FCCH information element, perhaps is sent out by some other means.
User terminal receives the initial timing lead from access point, and then this Timing Advance is used in all the subsequent uplink transmission on RCH and RACH.If user terminal is assigned to the FCH/RCH resource, its Timing Advance just can regularly be regulated by the RCH of FCCH information element the order that the access point in the field sends and regulate.So user terminal can be regulated its ul transmissions on RCH based on present Timing Advance, current Timing Advance equals the initial timing lead and adds that access point sends to whole timings adjustings of user terminal.
Each part and the various technology of MIMO wlan system described herein can be come time slot by various means.For example, the processing at access point and user terminal place can realize with hardware, software or their combination.For hardware was realized, processing can realize in following components and parts: one or more application-specific integrated circuit (ASIC)s (ASIC), digital signal processor (DSP), digital signal processing appts (DSPD), programmable logic device (PLD), field programmable gate array (FPGA), processor, controller, microcontroller, microprocessor, other is designed to carry out the electronic unit of function described here or their combination.
For software was realized, processing can realize with the module (for example process, function etc.) of carrying out function described here.Software code can be stored in the memory cell (for example memory among Fig. 7 732 or 782), and is carried out by processor (for example controller 730 or 780).Memory cell can realize in processor or outside the processor, and it is by being coupled on various means well known in the art and the processor communication in the rear situation.
Here the title that comprises makes things convenient for index, and helps the specific chapters and sections in location.These titles are not the scopes of descending described concept in order to limit it, and these concepts can be applied in other chapters and sections of entire description.
The description of above preferred embodiment makes those skilled in the art can make or use the present invention.The various modifications of these embodiment are apparent for a person skilled in the art, and the General Principle of definition can be applied among other embodiment and do not deviate from the spirit or scope of the present invention here.Therefore, the present invention is not limited to shown here embodiment, and will meet the most wide in range scope consistent with the principle that discloses and novel feature here.
Claims (18)
1. a use OFDM (OFDM) sends the method for signaling information in wireless multiple-input and multiple-output (MIMO) communication system, comprising:
On the first subchannel of forward control channel, send signaling information for first group of user terminal with the combination of the first encoding rate and modulation scheme; And
On the second subchannel of described forward control channel, send signaling information for second group of user terminal with the combination of the second encoding rate and modulation scheme, the combination of wherein said the second encoding rate and modulation scheme is different from the combination of described the first encoding rate and modulation scheme, and described the second subchannel is sent out after the first subchannel.
2. the method for claim 1 characterized by further comprising:
On the 3rd subchannel of described forward control channel, send signaling information for the 3rd group of user terminal with the combination of the 3rd encoding rate and modulation scheme, the combination of wherein said the 3rd encoding rate and modulation scheme is different from the combination of described the second encoding rate and modulation scheme, and described the 3rd subchannel is sent out after the second subchannel.
3. the method for claim 1 is characterized in that, described the first subchannel shows whether described the second subchannel is sent out in present frame.
4. use a kind of device in wireless multiple-input and multiple-output (MIMO) communication system of OFDM (OFDM), comprising:
Send data processor, be used for:
Process signaling information for first group of user terminal based on the combination of the first encoding rate and modulation scheme, and
Process signaling information for second group of user terminal based on the combination of the second encoding rate of the combination that is different from described the first encoding rate and modulation scheme and modulation scheme; And
Transmitter unit is used for:
Send the treated signaling information of described first user set of terminal at the first subchannel of forward control channel, and
Send the treated signaling information of described the second user terminal group at the second subchannel of described forward control channel, wherein said the second subchannel is sent out after described the first subchannel.
5. device as claimed in claim 4, it is characterized in that, described transmission data processor also is used for processing signaling information for the 3rd group of user terminal based on the combination of the 3rd encoding rate of the combination that is different from described the first and second encoding rates and modulation scheme and modulation scheme, wherein said transmitter unit also is used for sending at the 3rd subchannel of described forward control channel the treated signaling information of the 3rd user terminal group, and wherein said the 3rd subchannel is sent out after described the second subchannel.
6. device as claimed in claim 4 is characterized in that, described the first subchannel shows whether described the second subchannel is sent out in present frame.
7. use a kind of device in wireless multiple-input and multiple-output (MIMO) communication system of OFDM (OFDM), comprising:
Be used on the first subchannel of forward control channel combination with the first encoding rate and modulation scheme and send device for the signaling information of first group of user terminal; And
Be used on the second subchannel of described forward control channel combination with the second encoding rate and modulation scheme and send device for the signaling information of second group of user terminal, the combination of wherein said the second encoding rate and modulation scheme is different from the combination of described the first encoding rate and modulation scheme, and described the second subchannel is sent out after described the first subchannel.
8. device as claimed in claim 7 characterized by further comprising:
Be used on the 3rd subchannel of described forward control channel combination with the 3rd encoding rate and modulation scheme and send device for the signaling information of the 3rd group of user terminal, the combination of wherein said the 3rd encoding rate and modulation scheme is different from the combination of described the second encoding rate and modulation scheme, and described the 3rd subchannel is sent out after described the second subchannel.
9. device as claimed in claim 7 is characterized in that, described the first subchannel shows whether described the second subchannel is sent out in present frame.
10. one kind is used OFDM (OFDM) method at user terminal place reception signaling information in multiple-input and multiple-output (MIMO) communication system, comprising:
The signaling information that sends on first subchannel that is combined in forward control channel of reception with the first encoding rate and modulation scheme; And
If do not obtain the signaling information of described user terminal from described the first subchannel, then receive the signaling information that sends on the second subchannel that is combined in described forward control channel with the second encoding rate and modulation scheme, the combination of wherein said the second encoding rate and modulation scheme is different from the combination of described the first encoding rate and modulation scheme, and described the second subchannel is sent out after described the first subchannel.
11. method as claimed in claim 10 characterized by further comprising:
If do not obtain the signaling information of described user terminal from described the second subchannel, then receive the signaling information that sends on the 3rd subchannel that is combined in described forward control channel with the 3rd encoding rate and modulation scheme, the combination of wherein said the 3rd encoding rate and modulation scheme is different from the combination of described the second encoding rate and modulation scheme, and described the 3rd subchannel is sent out after described the second subchannel.
12. method as claimed in claim 10 characterized by further comprising:
After the decoding failure that runs into described forward control channel one subchannel, stop the processing of described forward control channel.
13. a kind of device in wireless multiple-input and multiple-output (MIMO) communication system of use OFDM (OFDM) comprises:
The receive data processor is used for:
The signaling information that sends on first subchannel that is combined in forward control channel of reception with the first encoding rate and modulation scheme, and
If do not obtain the signaling information of described device from described the first subchannel, then receive the signaling information that sends on the second subchannel that is combined in described forward control channel with the second encoding rate and modulation scheme, the combination of wherein said the second encoding rate and modulation scheme is different from the combination of described the first encoding rate and modulation scheme, and described the second subchannel is sent out after described the first subchannel; And
Be used to indicate the controller of the processing of described the first and second subchannels.
14. device as claimed in claim 13, it is characterized in that, described receive data processor also is used for: if do not obtain the signaling information of described device from described the second subchannel, then receive the signaling information that sends on the 3rd subchannel that is combined in described forward control channel with the 3rd encoding rate and modulation scheme, the combination of wherein said the 3rd encoding rate and modulation scheme is different from the combination of described the second encoding rate and modulation scheme, and described the 3rd subchannel is sent out after described the second subchannel.
15. device as claimed in claim 13 is characterized in that, described controller also is used for stopping the processing of described forward control channel after the decoding failure that runs into described forward control channel one subchannel.
16. a kind of equipment in wireless multiple-input and multiple-output (MIMO) communication system of use OFDM (OFDM) comprises:
Be used for receiving the device of the signaling information that sends on the first subchannel that is combined in forward control channel with the first encoding rate and modulation scheme; And
If do not obtain the signaling information of described equipment from described the first subchannel, then receive the device of the signaling information that sends on the second subchannel that is combined in described forward control channel with the second encoding rate and modulation scheme, the combination of wherein said the second encoding rate and modulation scheme is different from the combination of described the first encoding rate and modulation scheme, and described the second subchannel is sent out after described the first subchannel.
17. equipment as claimed in claim 16 characterized by further comprising:
If do not obtain the signaling information of described equipment from described the second subchannel, then receive the device of the signaling information that sends on the 3rd subchannel that is combined in described forward control channel with the 3rd encoding rate and modulation scheme, the combination of wherein said the 3rd encoding rate and modulation scheme is different from the combination of described the second encoding rate and modulation scheme, and described the 3rd subchannel is sent out after described the second subchannel.
18. equipment as claimed in claim 16 characterized by further comprising:
Be used for after the decoding failure that runs into described forward control channel one subchannel, stopping the device of the processing of described forward control channel.
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Also Published As
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| CN101166054A (en) | 2008-04-23 |
| CN101166072B (en) | 2014-11-12 |
| CN101166074A (en) | 2008-04-23 |
| CN100380857C (en) | 2008-04-09 |
| UA87973C2 (en) | 2009-09-10 |
| CN101232726A (en) | 2008-07-30 |
| CN1720686A (en) | 2006-01-11 |
| CN101232726B (en) | 2012-12-05 |
| CN1717901A (en) | 2006-01-04 |
| CN101425874B (en) | 2012-12-05 |
| CN100459535C (en) | 2009-02-04 |
| UA86752C2 (en) | 2009-05-25 |
| UA90080C2 (en) | 2010-04-12 |
| CN101582873B (en) | 2013-01-02 |
| CN101582873A (en) | 2009-11-18 |
| CN1717900A (en) | 2006-01-04 |
| CN101166072A (en) | 2008-04-23 |
| UA89611C2 (en) | 2010-02-25 |
| CN101425874A (en) | 2009-05-06 |
| UA86191C2 (en) | 2009-04-10 |
| UA86190C2 (en) | 2009-04-10 |
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