CN1981447A - Method and apparatus for closed loop transmission - Google Patents

Abstract

In a wireless communication system, a method and apparatus for closed loop transmission is disclosed. In accordance with the preferred embodiment of the present invention, a time frequency portion of an uplink frame is dynamically reserved as a sounding zone for uplink channel sounding. A first message is transmitted to a first subscriber station in a downlink frame assigning a time-frequency resource within the sounding zone, and a sounding waveform. Furthermore, a signal is received from the subscriber station within the assigned time-frequency resource, a partial channel response is determined from the received sounding signal, and the subsequent transmission to the subscriber station is tailored based on the at least partial channel response.

Description

The method and apparatus that is used for closed loop transmission

Technical field

The present invention relates generally to communication system, especially, relate to a kind of method and apparatus that is used for closed loop transmission.

Background of invention

In the mobile broadband cellular communication system, there are some physical-layer techniques, it need provide the knowledge of the channel response between the transmitter and receiver to transmitter.Utilize the transmission technology of the channel response between the transmitter and receiver to be called as the closed loop transmission technology.A use that example is the closed-loop transmit antenna array at transmitter place of closed loop transmission.Closed-loop transmit antenna array is the array of a plurality of transmitting antennas, wherein is fed to the signal weighting by rights of each antenna, so that control the characteristic of institute's transmit signal energy according to some predefined optimisation strategy.Usually, closed-loop transmit antenna array is weighted the aerial signal of being launched based on the knowledge of the space-frequency channel response between each transmitting antenna and each reception antenna, and attempts optimizing the characteristic of the received signal of being handled by receiving equipment.For the transmitter of single antenna, transmitter can use channel knowledge to make the channel preequalization, so that reduce even eliminate the needs of the multiple connection at receiver place being received equilibrium.The knowledge that has channel response at the transmitter place also can be used for selecting best modulation and code rate, is used for using to receiver emission data the time.

Usually, there are two kinds of methods that are used for providing the channel knowledge between each transmitting antenna and each reception antenna to transmitter.Discussion herein concentrates on the down link of cellular system, and wherein base station (BS) is transmitter, and subscriber station (SS) is a receiver.

First method is based on the feedback message from SS, wherein SS measures the channel response between BS antenna and the SS antenna, and feedback message is launched back BS, and described feedback message comprises the enough information that makes BS can rebuild downlink channel response and carry out closed loop transmission.For example, the quantised versions can the feeding back downlink link channel estimated of SS.

Second method is based on the reciprocity of the RF channel response in the TDD system.In static state (promptly, zero velocity) in the TDD system, the RF propagation channel is reciprocity, this means the preset time-the down link RF channel matrix (wherein matrix refers to that each transmits and receives the channel gain between the antenna) at Frequency point place is the matrix transpose of the up link RF channel matrix at identical T/F point place simply.Therefore in the TDD system,, then can obtain downlink channel response from uplink data transmission sometimes if transfer of data comprises pilot signal.Yet in the digital communication system in modern times, professional (browsing such as web) is normally asymmetrical, means may not exist with each downlink transmission associated uplink transmission.Perhaps, in broadband system, typical uplink data transmission can have the bandwidth littler than typical downlink transmission.These problems may make the major cycle based on the closed loop transmission in the system of reciprocity.Therefore, need a kind ofly can overcome the closed loop transmission method of these restrictions and the Signalling method that is associated.

Description of drawings

Fig. 1 is the block diagram of communication system.

Fig. 2 is the block diagram that single data flow is delivered to the closed-loop transmit antenna array of the receiving equipment with one or more reception antennas.

Fig. 3 is the block diagram that a plurality of data flow is delivered to the closed-loop transmit antenna array of the receiving equipment with one or more reception antennas.

Fig. 4 is to use the block diagram of the broadband emission system that is directed at frequency domain of closed-loop transmit antenna array.

Fig. 5 is the sequential chart of time division duplex (TDD) frame, and wherein the time is divided into down link (DL) part or frame and up link (UL) part or frame, and down link can take identical frequency bandwidth with uplink frame.

Fig. 6 is the integrated diagrammatic sketch of uplink frame, and how its T/F part that shows uplink frame is reserved for the different examples of detecting area.

Fig. 7 shows from a uplink frame to another uplink frame, and detecting area is the diagrammatic sketch of the example of dynamic change how.

Fig. 8 shows the diagrammatic sketch of the tdd frame of non-coupling detection method, and wherein base station (BS) launches message to subscriber station (SS) in the DL frame, instruction SS emission detection signal in the uplink sounding district.

Fig. 9 shows the diagrammatic sketch of the non-coupling detection method of the closed loop transmission of following in next descending chain circuit frame.

Figure 10 shows the flow chart of the operation of the non-coupling detection method in the down link.

Figure 11 shows the flow chart of the operation of the non-coupling detection method in the up link.

Figure 12 shows the sequential chart of coupling detection method, wherein simultaneously provides downlink data allocation to subscriber station (SS), and it is included in the order of emission detection signal in the uplink sounding district.

Figure 13 shows the sequential chart of the coupling detection method of following closed loop transmission.

Figure 14 shows the flow chart of the operation of the non-coupling detection method in the down link.

Figure 15 shows the flow chart of the operation of the non-coupling detection method in the up link.

Figure 16 is the T/F figure that two kinds of methods of the detectable signal separability that realizes in the identical time-frequency resources have been described.

Figure 17 shows the device that is used to provide closed loop transmission.

Figure 18 shows the device that is used to carry out channel detection.

Summary of the invention

One aspect of the present invention comprises a kind of Signalling method, be used for providing the knowledge of the channel response between each transmitting antenna and each reception antenna to transmitter, with antenna array calibration by hypothesis, survey via uplink channel, realize the processing of closed loop single current and multithread emission array.Some other application schemes also are feasible, for example: the preequalization that is used for single system of transmit antennas; With definite best modulation and encoding scheme, be used for when receiving equipment is launched, using.In order to simplify, the present invention has been proposed: promptly provide required and be used in the channel knowledge that the transmission weight of closed loop antenna array system is set when subscriber station (SS) is launched to base station (BS) from following viewpoint.Will be appreciated that the present invention is applied to such situation, promptly wherein the effect of BS and SS is opposite with effect described herein.For example, the present invention can be applied to such situation, wherein provides channel knowledge to SS, to realize the closed loop transmission from SS to BS.Therefore, although this description will mainly concentrate on the situation of BS execution at the closed loop transmission of SS, but term " source communication unit " will refer to carry out the communication unit (for example, BS, SS or other transceiver) at the closed loop transmission of " target communication unit ".

And, used some term in this application interchangeably: term " channel response "." frequency-selective channel profile ", " space-frequency channel response ", they all refer to the channel response information of base station needs, facilitate the use the closed loop transmission technology.Term " waveform " and " signal " have also been used interchangeably.Receiving equipment can be base station (BS), subscriber station (SS) or its any combination.And transmitter can be BS, SS or its any combination.In addition, if system has transponder, repeater or other similar equipment, then receiving equipment or transmitter can be transponder, repeater or other similar equipment.If BS carries out the closed loop transmission at transponder/repeater, then transponder and repeater can be regarded as being equal to SS.If repeater is carried out the closed loop transmission at SS, then transponder and repeater can be regarded as being equal to BS.Term " fast Fourier transform (FFT) " and " invert fast fourier transformation (IFFT) " refer to discrete Fourier transform (DFT) (or similarity transformation) and inverse discrete Fourier transformer inverse-discrete (or similarity transformation) respectively.

One aspect of the present invention is the dynamic reservation of the detecting area on the up link.Detecting area is the reserved area of up link, and SS can be at the special-purpose detection waveform of described zone emission, and described detection waveform makes the base station can measure uplink channel responses, also is called as the frequency-selective channel profile.By hardware calibration technology as known in the art, BS can determine downlink channel response (perhaps frequency-selective channel profile) from measured uplink frequency selective channel profile.Should be noted that in some cases SS can only (for example launch on the subclass of uplink channel bandwidth, for identical total transmitting power, power spectral density by increase transmits overcomes noise), so BS may only can determine and use the local channel response about this SS.

One aspect of the present invention is to be used for determining the existence of detecting area and the optional signaling of characteristic.BS can be by launching information element (IE) (for example UL-MAP in the IEEE802.16 standard), the existence of signaling detecting area in uplink control channel.This IE can point out zero-time (normally entering the baud number of UL) and duration (measuring with the baud number of OFDM usually).To not take uplink bandwidth completely if survey baud, then IE will comprise the information that the frequency of having specified detecting area takies.Should be noted that do not need to be used to specify detecting area signaling-on the contrary, it helps to reduce the expense in the actual detection assignment of carrying out at specific SS.

One aspect of the present invention is a kind of Signalling method that is used to specify the uplink sounding transmission characteristic (that is, T/F is surveyed resource and definite detectable signal) that will be used by SS.

One aspect of the present invention is a kind of method that is used for a plurality of detection waveforms of assignment, this detection waveform is launched in identical time-frequency resources by different SS (perhaps by the different antennae on the identical SS), but because the attribute of waveform, they can be separated by BS.When having realized a plurality of transmitting antenna, this surveys.

One aspect of the present invention is a kind of method that is used for assignment SS, is used for emission detection signal in the specific time-frequency resources of uplink frame.

One aspect of the present invention is a kind of Signalling method, and it gives transfer of data at SS with downlink allocation, and emission detection signal in the special time-frequency resource of assignment SS in the UL frame simultaneously.

In the chapters and sections of the application's back, described of the present invention other aspect.The present invention has many advantages: this Signalling method provides the flexibility and the signaling efficient of height.This method has realized surveying dynamic allocation of resources at the UL of a plurality of SS, and has handled such situation, and wherein SS has single or multiple transmitting antenna.This method also provides and has been used to make BS to make to survey the multiple technologies that waveform separates, and it makes a plurality of SS antennas (no matter this antenna all is positioned on the equipment or is positioned on a plurality of SS) to survey on the resource at identical T/F survey UL.This Signalling method is also with the additive method complementation of determining the UL channel response.For example, if BS can determine the UL channel response from the data that SS launches at UL, then can make exploration operation stop using (or closing).Part as the method that is used to provide a plurality of separable detection waveforms, this Signalling method provides the means that are used for selecting probe transmission on frequency, so that increase the transmitting power of each subcarrier, thereby be supported in the SS that operates in the low SNR environment better.And the waveform that is used for probe transmission is designed to have low peak-to-average power ratio, and has the interference capability that suppresses other sub-districts by means of its their cross correlation.At last, the detection waveform that is provided by the Signalling method that is proposed is designed to realize the efficient channel estimation at BS place, can follow the tracks of the time fluctuation in the channel response thus.

Embodiment

Forward accompanying drawing now to, wherein similar reference number is represented similar parts, and Fig. 1 is the block diagram of communication system 100.Communication system 100 comprises: a plurality of sub-districts 105 (only illustrating one), each sub-district has base station (BS, or base station) 104, and it is with a plurality of subscriber stations (SS) 101～103 communications.If carry out the closed loop transmission at SS 101 on down link, then BS 104 can be called as source communication unit, and SS 101 can be called as target communication unit.If carry out the closed loop transmission from SS 101 to BS 104 on up link, then SS 101 can be called as source communication unit, and BS 104 can be called as target communication unit.In a preferred embodiment of the invention, communication system 100 is utilized Orthodoxy Frequency Division Multiplex (OFDM) or is comprised the architecture based on multicarrier of adaptive modulation and coding (AMC).This architecture can also comprise: use such as CDMA multiple carrier (MC-CDMA), multi-carrier direct sequence CDMA (MC-DS-CDMA), the orthogonal frequency with one dimension or bidimensional spread spectrum and the such spread spectrum of code division multiplex (OFCDM), perhaps can be based on better simply time-division and/or frequency division multiplex/multiple access technology, the perhaps combination of these multiple technologies.Yet in interchangeable embodiment, communication system 100 can be utilized other cellular communication system agreement, such as, but be not limited to TDMA or direct sequence CDMA.

Fig. 2 is the block diagram of closed-loop transmit antenna array, and described closed-loop transmit antenna array is transmitted the part of the source unit of single data flow as the receiving equipment of a target communication unit part that has one or more reception antennas to conduct.Before inlet flow 204 is fed to a plurality of transmitting antennas 201, use multiplier 203 that it is multiplied each other with transmission weight 205.Inlet flow 204 is multiplied each other with transmission weight 205, and wherein transmission weight is an example of the spatial character of customization transmission based on local channel response at least.Be used for determining that from channel response the method for transmission weight is well known in the art.Propagate by matrix channel 108 from the signal of a plurality of transmitting antenna 201 emissions, and receive by a plurality of reception antennas 202.Use multiplier 203 that the signal of reception on a plurality of reception antennas 202 is multiplied each other with receiving weight 206, and by summation device 209 summations, to produce output code flow filament 207.Transmitter only has among the embodiment of an antenna therein, can not customize the spatial character that transmits; Yet, can be based on local channel response at least, such as the complex gain (for example, in preequalization is used) of each subcarrier, perhaps modulation of using on the subcarrier that transmits and coding customize other characteristics that transmit.

Fig. 3 is the block diagram of closed-loop transmit antenna array, and described closed-loop transmit antenna array is transmitted the part of the source unit of a plurality of data flow as the receiving equipment of the target communication unit that has one or more reception antennas to conduct (for example mimo system) part.Before a plurality of inlet flows 304 are fed to a plurality of transmitting antennas 301, use multiplier 303 that it is multiplied each other with transmission weight 305.Propagate by matrix channel 308 from the signal of a plurality of transmitting antenna 301 emissions, and receive by a plurality of reception antennas 302.Use multiplier 303 that the signal of reception on a plurality of reception antennas 302 is multiplied each other with receiving weight 306, and, export a plurality of code element stream 307 to produce by summation device 309 summations.Inlet flow 304 is multiplied each other with transmission weight 305, and wherein transmission weight is another example of the spatial character of customization transmission based on local channel response at least.The embodiment of other of generation output code flow filament 307 also is feasible, such as using or not use the maximum likelihood that receives weight 306 and multiplier 303 to detect or eliminate continuously.

Fig. 4 is the block diagram that is directed at the emission system of frequency domain, such as Orthodoxy Frequency Division Multiplex (OFDM) or cyclic prefix single carrier (CP single carrier), wherein the transmission before, the transmission technology of execution graph 2 and Fig. 3 in frequency domain.In the CP single-carrier system, at first make one or more data flow 401 forward frequency domain to by one or more FFT 402, and by the weighting of 403 pairs of this frequency domain data stream of frequency domain weighting device.In OFDM, directly one or more data flow 401 are sent to frequency domain weighting device 403, and do not use FFT 402.Frequency domain weighting device 403 is at the frequency slots in each subcarrier or the frequency domain (frequency bin), realized the weighted function shown in the radiating portion of Fig. 2 and Fig. 3.Therefore, can be spatially or on the frequency, perhaps these both on, utilize the system of the type, customization transmits.Then, make the output of frequency domain weighting device 403 rotate back into time domain by IFFT 404.Add Cyclic Prefix 405, as known in the art.Then, before the signal that will be launched sends to transmitting antenna 407, carry out emission filtering 406.

Specify the existence and the characteristic of detecting area

One aspect of the present invention is the dynamic reservation of the detecting area in the up link (UL) of time division duplex (TDD) frame.Fig. 5 shows the sequential chart of a frame 501 of TDD system, and it is made up of two parts usually: down link (DL) frame or interval 502 and uplink frame or interval 503.DL all takies identical frequency band with UL, and replaces in time.In the communication system with base station (BS), DL is used for the transmission undertaken by subscriber station (SS), and UL is used for the transmission undertaken by subscriber station (SS).Tdd frame is made up of a DL frame of following by a UL frame usually, although the variation scheme also is feasible.The relative length of DL frame and UL frame can be regulated with the relative level of UL business according to the DL of expection is professional.

Detecting area is the T/F part of the special use of up link tdd frame, and it is dynamically reserved, and is used for by the special-purpose detection waveform of SS transmission, so that BS can measure uplink frequency selective channel profile or channel response to small part.For the existence and the characteristic of signaling detecting area, BS can be in control channel (preferably UL control channel, for example, it is called as UL-MAP in IEEE 802.16) the special-purpose information element (IE) of emission.In order to make an explanation, this IE will be called as Sounding_Zone_Presence_IE () (there is information element in detecting area), and it comprises definite appointment detecting area and be positioned at information where on time and frequency.Should be noted that the signaling that does not need to be used to specify detecting area; Yet, its can reduce by broadcast some for the equal Useful Information of whole SS carry out at the expense in the actual detection assignment of specific SS.

The detecting area that is distributed can be arranged in uplink frame any time-frequency part.Early detecting area is placed the UL frame, increased the time utilized that is used to handle the detection waveform that is received for the base station.Place UL frame with detecting area late period, by newer channel information (tdd frame with the back is relevant) is provided, realized the tracking preferably that channel time is changed.

Fig. 6 shows the some examples that detecting area 602 are placed in the position in the UL frame 503.Can uplink frame 503 any time-dynamically reserve detecting area in the frequency part.Early detecting area is placed the UL frame, increased the time utilized that is used to handle the detection waveform that is received for the base station.Place UL frame with detecting area late period, by newer channel information is provided, realized the tracking preferably that channel time is changed.Should be noted that by not launching Sounding_Zone_Presence_IE (), can from the UL part of frame, omit this detecting area simply.Replacedly, the information among the Sounding_Zone_Presence_IE () can be launched together with such indication, and promptly described indication points out that the frame subsequently of certain number will have the detecting area that has with the identical characteristic of the characteristic of appointment among this IE.This will eliminate launch the needs of Sounding_Zone_Presence_IE () in the control channel of each frame.

Can dynamically reserve detecting area 602 based on frame one by one, as shown in Figure 7.Fig. 7 shows a plurality of continuous tdd frames 501, and each frame is made up of descending chain circuit frame 502 and uplink frame 503.In Fig. 7, detecting area 602 is shown in some but not dispatches in the whole uplink frame.And in Fig. 7, some uplink frame is shown as has the different time-frequency resources of distributing to detecting area.By based on frame update one by one and emission Sounding_Zone_Presence_IE (), can distribute signaling to SS by current detecting area.By realizing the dynamic reservation of detecting area, BS can adapt to different situations effectively.Its some example is as follows.In one example, based on the expection number of the SS that need in being reserved with the frame of detecting area, survey, select the size of detecting area.An aspect that influences it is that the number of the SS of the activity on the interval may change any time, therefore the size that can dynamically regulate detecting area in view of the above.And, also may there be the closed loop of being undertaken and the mixing of open-loop transmission by BS, therefore may need to change in view of the above the size of detecting area.In order to adapt to the situation of this situation and other, make the expense minimum of detecting area simultaneously, can be according to from the present frame to the next frame and change the size of detecting area.

In about preferred embodiment as the system of IEEE 802.16, following structure detecting area.Use the signaling parameter of the OFDMA pattern of IEEE 802.16d air-interface standard that detailed example is provided, but the invention is not restricted to this specific example.

Frequency band in the OFDMA pattern of IEEE 802.16d is divided into 192 frequency slots, and wherein each frequency slots comprises 9 OFDM subcarriers.Example for 802.16:

In order to make up the frequency part of detecting area, frequency band is divided into 32 look-in frequency pieces, wherein each piece comprises 192/32=6 frequency slots.This means that each look-in frequency piece comprises 54 OFDM subcarriers.

According to the level of the business that will use closed loop transmission, distribute the OFDMA symbol interval (also being called as baud or OFDM code-element period) of certain number to detecting area, it can dynamic change.

In order to simplify, reserve detecting area at the place, end of the initial of UL frame or UL frame.Replacedly, can explicitly point out the definite position in the UL frame, but this needs the extra signaling bit among the Sounding_Zone_Presence_IE ().

According to preferred structure policy above, detecting area is made up of the two-dimensional grid of surveying 32 look-in frequency pieces of baud in certain number, and described detection baud can dynamically be regulated according to the level of the DL business that will use closed loop transmission.

In the preferred embodiment about the system as 802.16, Sounding_Zone_Presence_IE () message comprises following message:

-point out that this IE is the control code of Sounding_Zone_Presence_IE ()

Detecting area length in the-symbol interval number (3 bit)

The position of-detecting area (1 bit).If it is set to 1, then detecting area is placed in the end of UL frame.If it is set to 0, then detecting area is placed in the initial of UL frame.

Should be noted that by specifying detecting area start element at interval but not use simple 1 bit position field, detecting area at random can be placed in any element position in the UL frame.(this method need more than a bit).In interchangeable embodiment, if transfer of data and probe transmission be constructed to them can be not interfering with each other mutually significantly, then except the channel detection transmission, detecting area can also allow some transfer of data to occur in the detecting area.This embodiment can be used for using in the system of CDMA multiple carrier form, wherein for take the probe transmission of identical time-frequency resources different with the transfer of data assignment and the spreading code of quadrature preferably.

In case determined the characteristic of detecting area, there are two kinds of basic Signalling methods, be used for being used for distributing time-frequency resources at detecting area, so that will surveying waveform, SS is transmitted into BS.First method is, BS is generated and emission message, it can be at the control channel of DL (preferably in the UL control channel, in IEEE 802.16d system, also be called as UL-MAP) in emission, its assignment the time-frequency resources that uses by SS when on UL, surveying and survey waveform (or detectable signal).This is surveyed waveform and is preferably specified by the combination of separability pattern, separability parameter and detection sequence index, and it is preferably incorporated in this message.Other information is utilized the known BS identification number of other means such as SS, also can together use together with the message that is received by SS, with the definite probing wave shape of determining to be used by SS.

Second method is, probe instructions incidentally on the downlink data allocation in the DL control channel.First method is called as " non-coupling detection ", and second method is called as " coupling is surveyed ".This two kinds of methods are described in the chapters and sections below.

In interchangeable embodiment, the explicit message (such as UL_Sounding_Zone_Presence_IE () (there is information element in the uplink sounding district)) that is used for remaining in advance a part of UL of channel detection purpose is not used, and carry out the reservation of the UL time-frequency resources be used to survey purpose by the base station, and do not notify SS.In this embodiment, BS generates simply and launches such message, be that described message is the time-frequency resources that used by SS when surveying on UL of SS assignment and surveys waveform (or detectable signal), wherein this detection waveform is preferably by the combination appointment that is preferably incorporated in separability pattern, separability parameter and detection sequence index in this message.

Non-coupling process

In first method, BS reserves the T/F part of UL frame as the detecting area that is used for the UL channel detection, generates message and in the DL frame message is transmitted into SS.This message assignment or specified the time-frequency resources in the detecting area and surveyed waveform.This surveys waveform preferably by the combination assignment of the separability pattern in the message, separability parameter and detection sequence index.

Use this method to be used for to be as an example of 802.16 system, (and preferably in UL control section) definition information element (IE) or message in control channel preferably, it comprises the information of time-frequency resources that assignment should use and the detection waveform that should use in this time-frequency resources in the UL detecting area.This information element is to SS notifying time-frequency resource and survey employed signal in detecting area, and this information element is called as UL_Uncoupled_Sounding_IE () (the non-coupling detection information of up link element).Receive in the DL frame from the UL_Uncoupled_Sounding_IE () that is addressed to SS of BS afterwards, SS determines the detectable signal that will use and this detectable signal of emission in the time-frequency resources of the institute's assignment in the UL frame.How to specify the detailed content of the characteristic of detectable signal/waveform will be in following elaboration.

Fig. 8 comprises the T/F diagrammatic sketch, and it shows the non-coupling detection method that is used for as 802.16 system.In the figure, wherein, the control information 803 of emission comprises in DL 502: UL_Uncoupled_Sounding_IE (), it is the non-coupling detection assignment message 808 that institute generated and be launched into first subscriber station (SS#1) basically.Assignment message 808 is surveyed in this non-coupling that is addressed to SS#1, by time-frequency resources in the assignment detecting area and detection waveform, transmission of uplink probe transmission 804 in the UL part 503 that SS informs at frame.As shown in Figure 8, should be noted that control information 803 can also comprise the data allocations about SS#1, it is that a part 805 of reserving DL 502 is used for the message at the transfer of data of SS#1 simply.In Fig. 8, data allocations message and the follow-up transfer of data at SS#1, irrelevant with the order that is used for emission detection in the UL part of frame perhaps are " non-coupling " with it.In other words, non-coupling detection assignment message 808 (perhaps UL_Uncoupled_Sounding_IE ()) is independent of the data allocations message 810 in the information 803.Following chapters and sections have been described a kind of interchangeable embodiment, and wherein data assignment and the uplink sounding assignment about DL is coupled, and launching in an information element in control channel.

Fig. 9 comprises the T/F diagrammatic sketch, and it shows non-coupling detection assignment message 808 and how realize the closed loop transmission strategy on DL 502.At first, assignment message 808 (perhaps UL_Uncoupled_Sounding_IE ()) is surveyed in the non-coupling of emission in the UL control channel (control information 803) of base station in the DL of first frame part 502.This message has been the SS assignment time-frequency resources in the detecting area and survey waveform.SS is according to the instruction that provides among the UL_Uncoupled_Sounding_IE () in the DL part 502 of first frame (based on the time-frequency resources of institute's assignment and the detection waveform of institute's assignment), transmission of uplink detectable signal 804 then.The base station receives detectable signal 804, estimating or to be determined to small part UL channel response, and the uplink channel responses of estimating partly is transformed to downlink channel response.Based on this local channel response at least, use the characteristic of this downlink channel response customization then, to be provided at by the closed loop transmission 904 on the consistent frequency band part of the shared frequency band part of uplink sounding waveform 804 at the subsequent transmission of SS.In other words, based on the detection waveform 804 that in the UL 503 of adjacent frame the preceding, receives, carry out closed loop transfer of data 904 from SS.In interchangeable embodiment, can be used for the closed loop transfer of data that any subsequent frame is carried out from surveying the information that waveform 804 recognizes, needn't only be used for shown in Figure 9 immediately following after this closed loop transfer of data of carrying out of frame place.About an example of this situation is that channel is slowly change the time.In this case, can be based on the information of being recognized from the detection waveform of the previous emission of any number, carry out closed loop transmission, this closed loop transmission will be not limited only to the shared consistent frequency band part of frequency band part of the uplink sounding waveform that receives among the UL 503 of adjacent frame the preceding shown in Figure 9 804.Otherwise Fig. 9 only shows the sequential chart about the high mobility situation of the most instant channel knowledge of needs.Customization comprises with the example that closed loop transmission is provided at the characteristic of SS, but be not limited to: calculate and use and penetrate weight (spatial emission weight) about the recurrence of each transmitting antenna, calculating and application are penetrated weight (space-frequency transmission weight) about each user's of each antenna recurrence, select suitable modulation/coding scheme (adaptive modulation and coding), and calculate and use at each user's recurrence and penetrate weight with compensating frequency selectivity decline (preequalization).The technology that is used for calculating from given channel response the transmission weight of these types is obtainable in the art.

Figure 10 shows the flow chart of the operation of the non-coupling detection method in the down link.This process starts from step 1001, wherein dynamically reserves the T/F part of uplink frame, as the detecting area that is used for the UL channel detection.Flow process advances to step 1002, wherein generate message and in descending chain circuit frame to SS emission message, described message to the SS assignment temporal frequency resource in the detecting area and survey waveform so that be used for surveying uplink channel by SS.For ofdm system, time-frequency resources is the set of subcarrier and the set of OFDM code-element period or baud.Should be noted that subcarrier in this set need not be adjacency (for example, referring to Fig. 6 602), and code-element period needs not be adjacency.

Figure 11 shows the flow chart of the operation of the non-coupling detection method in the up link.This process starts from step 1101, and wherein the indication of BS in detecting area joined the detectable signal that receives in the time-frequency resources from SS.Flow process advances to step 1102, and wherein BS is determined to the small part channel response channel response information of partial-band (for example, about) from the detectable signal (or waveform) that is received.At last, in step 1103, the base station based on this at least local channel response customization at the characteristic (for example, power, modulation and code levels, transmitting antenna weight, spatial character etc.) of the follow-up emission of SS, so that the closed loop transmission at SS to be provided.

The coupling detection method

Be used for informing that at UL second embodiment of SS emission detection waveform is a probe command incidentally on the DL data allocations message in the control channel (preferably DL control channel, the perhaps DL-MAP in the term of IEEE 802.16d).Its strategy is, make the base station on control channel, launch an IE or control messages, (be called as DL_Coupled_Sounding_Allocation_IE () (the assignment information element is surveyed in the down link coupling), it comprises two parts: first reserves a part of DL frame, is used for the transfer of data at specific SS.Second portion provides the breviaty set of probe instructions, and it will inform SS emission detection in the UL of this frame part.In order to reduce the required signaling amount of surveying waveform characteristic that is used to specify, among the DL_Coupled_Sounding_Allocation_IE () not explicitly comprise the frequency characteristic of surveying waveform, but the frequency characteristic of the DL data allocations that comprises in the first by IE is implicitly obtained surveying the frequency characteristic of waveform by SS.This method has the advantage of minimizing to the needs of the frequency characteristic of signaling detection waveform.When BS understood DL in next tdd frame and will comprise the DL data allocations with frequency characteristic identical with DL data allocations in the present frame, this method had advantage.In this case, BS can pass through emission DL_Coupled_Sounding_Allocation_IE (), and infers the frequency characteristic of the detection waveform of being asked according to the frequency characteristic of the DL data allocations among the DL, has saved some signaling information.

Figure 12 comprises sequential chart, and it shows the coupling detection method and how to operate.Than Fig. 8, the assignment simultaneously of single downlink allocation control messages 1215 in the control information 803 (control channel) or information element (IE) is about the DL data allocations 1205 of SS#1, and comprises the required information that is used for emission detection waveform 1206 on the band portion identical with the shared band portion of downlink data allocation 1205 of SS.Use detection 1206 by BS, to realize next frame but not the closed loop DL transfer of data among the DL of present frame by the SS emission.

Like this, as shown in figure 13, the probe transmission in the UL part 503 of first tdd frame is followed the DL closed loop transfer of data 904 among the DL of next tdd frame.The assignment simultaneously of single downlink allocation control messages 1215 in the control information 803 (control channel) or information element (IE) is about the DL data allocations 1205 of SS#1, and comprises the required information that is used for emission detection waveform 1206 on the band portion identical with the shared band portion of downlink data allocation 1205 of SS.Use detection 1206 by BS, to realize next frame but not the closed loop DL transfer of data 904 among the DL of present frame by the SS emission.In interchangeable embodiment, be used in the closed loop transfer of data that any subsequent frame is carried out from surveying the information that waveform 1206 recognizes, needn't only be used for shown in Figure 13 immediately following after the closed loop transfer of data carried out of frame place.About an example of this situation is that channel is slowly change the time.In this case, can be based on the information of recognizing from the detection waveform of the previous emission of any number, carry out closed loop transmission, this closed loop transmission will be not limited only to the shared consistent frequency band part of frequency band part of the uplink sounding waveform that receives among the UL 503 of adjacent frame the preceding shown in Figure 13 1206.Otherwise Figure 13 only shows the sequential chart about the high mobility situation of the most instant channel knowledge of needs.

Figure 14 shows the flow chart of the operation of the coupling detection method in the down link.This process starts from step 1401, wherein dynamically reserves the T/F part of uplink frame, as the detecting area that is used for the UL channel detection.Flow process advances to step 1402, wherein generate message and in descending chain circuit frame, launch message to SS, and described message assignment the time-frequency resources in the DL frame of DL data so that SS receives DL, and to the SS assignment temporal frequency resource in the detecting area and survey waveform so that be used for surveying uplink channel by SS.In step 1402, be used to receive the temporal frequency resource of DL data, the implicitly frequency resource in the assignment detecting area to SS based on assignment.

Figure 15 shows the flow chart of the operation of the non-coupling detection method in the up link.This process starts from step 1501, wherein receives the detectable signal from SS in the time-frequency resources of the assignment of BS in detecting area.Flow process advances to step 1502, and wherein BS is determined to the small part channel response channel response information of partial-band (for example, about) from the detectable signal (or waveform) that receives.At last, in step 1503, the base station based on this at least local channel response customization at the characteristic (for example, power, modulation and code levels, transmitting antenna weight, spatial character etc.) of the follow-up emission of SS, so that the closed loop transmission at SS to be provided.

Specify and survey waveform

As described previously, in a preferred embodiment, detecting area is made up of the time-frequency lattice of surveying 32 look-in frequency pieces of baud in certain number, and described detection baud can be according to the level of the DL business that will use closed loop transmission and dynamic adjustments.These chapters and sections have been described and how to be distributed the time-frequency resources in the UL detecting area and how to inform which waveform SS launches to SS.

In a preferred embodiment, to surveying distribution or assignment by the SS of emission detection information on UL, this detection distributes or assignment has specified SS will be used for the time-frequency resources of the detecting area of emission detection waveform.In a preferred embodiment, give the time-frequency resources of SS, form by the set of the adjacency of the look-in frequency piece of crossing in the detecting area frequency in the OFDM baud-spaced.Other embodiment is such as distributing non-adjacent frequency chunks or surveying baud more than one, also within the scope of the invention.Key point is, comes fixed time-frequency resource by surveying assignment.

Except the time-frequency resources that is used to survey, SS must understand will use for which type of particular transmission signal or waveform in the time-frequency resources of assignment.In a preferred embodiment, this is by specifying the several parameters of surveying waveform to realize that it comprises this parameter:

-sequence index.The specific sequence that it has specified SS will use in this time-frequency resources.As known in the art, ((Generalized Chirp-like, GCL) sequence is preferential based on described Generalized C hirp-Like to make this sequence for Generalized Chirp-like, GCL) the low cross correlation properties of sequence owing to Generalized C hirp-Like.Yet, also can use the sequence except the GCL sequence.Advantageously, at the set of the different GCL sequence of a plurality of channel base station altogether use, the GCL sequence of other that low thus cross correlation properties can suppress to launch from other common channel area.In a preferred embodiment, specify the GCL sequence that is used to survey as follows.At first, SS will instruct set (surveying tape) and the separability type (or pattern) and the separability parameter (will define below) (they all define) of look-in frequency piece of the adjacency that SS surveys from BS, calculating frequency domain detection sequence L during being received from the message UL_Uncoupled_Sounding_IE () of BS _SLength, it equals the number of shared subcarrier.SS determines greater than L then _SMinimum prime number N _GDetection sequence is like this, as a result:

$S_u\left(k\right)=\exp \{-j2\mathrm{\πu}\frac{k(k+1)}{{2N}_G}\},k=0\·\·\·L_S-1$

Wherein k is the sequential element index, and u is called as " sequence class index ", from the sequence index of institute's assignment and the Cell ID of BS, and following calculating u:

The decimal value of minimum 3 bits of v1=1+Cell ID

The decimal value of v2=1+ sequence index

u＝((v1)(v2)-1)mod(N _G-1)+1

In interchangeable embodiment, sequence index is pointed to the specific class index u in the table of storing in advance.This u is used to define detection sequence as mentioned.Can give different common channel areas with different table assignments by predetermined mode or by dynamic assignment, can suppress other GCL sequence from other common channel area emission.

-separability type (or pattern) sign.This sign is pointed out employed separability method, and wherein the separability method refers to such method, and promptly by this method, a plurality of detection waveforms of being launched can take identical time-frequency resources, is separable at BS receiver place simultaneously.The first separability type be make survey that waveform only utilizes or holding time-frequency resource in the subclass of the subcarrier that comprises.Like this, different SS is the disjoint subcarrier group in service time-frequency resource simultaneously, and can not disturb the detectable signal of SS each other.In a preferred embodiment, belong to " pectination " structure of surveying the subcarrier that distributes, disjoint subcarrier group is provided by using to cross over.In other words, survey waveform only in holding time-frequency resource every N subcarrier.Taking of the leap subcarrier of the type is the form of frequency division that interweaves, and can be called as and select subcarrier.Other SS surveys waveform can take the identical time-frequency resources of surveying in distributing, and surveys different " start offset " every N subcarrier that distributes but taken to cross over.Utilize a plurality of detection waveforms to take and cross over this fact of different set of surveying distribution, realized separability by this method every N subcarrier.The detection of the type also is called as frequency interlacing or selects subcarrier, and the separability of utilizing frequency to select is perhaps utilized the separability of frequency division, perhaps by the different shared sub-carrier interleavings of detection waveform is separated.Element 1601,1602,1603,1604 and 1620 explanations are passed through in the detection of the type in Figure 16.The second separability type makes each subcarrier of surveying waveform holding time-frequency assignment, and a plurality of detection waveforms can take identical T/F assignment, as long as they have cross correlation properties, this cross correlation properties makes BS can estimate the channel response of each SS of launching in the comfortable identical T/F assignment.The detection sequence separability of the type is passed through element 1611,1612,1613,1614 and 1621 explanations in Figure 16.Should be noted that in a preferred embodiment the separability sign has been pointed out in two separability patterns.Yet if desired, the present invention allows the separability sign can point out more than two separability patterns.

-separability parameter: for above-described two types separability, following use separability parameter: for frequency interlacing or select the subcarrier separability, the separability parameter has been specified subcarrier set offset index (that is, taking in may gathering which of every N subcarrier N by surveying waveform).Survey the sequence separability of distributing for crossing over, the separability parameter provides extra information, and it is used for determining concrete detection waveform together with sequence index.In a preferred embodiment, sequence index has been determined employed basic sequence, and the separability parameter has been pointed out will be applied to the circulation time shift amount (in ofdm system, after IFFT) of surveying waveform in time domain before transmission.In this case, the separability parameter has pointed out how to revise the sequence that obtains from sequence index, to obtain final detection waveform.

-a plurality of antenna parameters: for the SS with a plurality of transmitting antennas, this parameter has pointed out that SS should still survey on the one antenna on its whole transmitting antennas.Replacedly, this parameter can be expanded to explicitly to confirm to survey which antenna set by SS.If this parameter has pointed out to survey a plurality of antennas, then use the separability parameter, and the remaining transmitting antenna of assignment implicitly uses the follow-up separability parameter in the sequence, simultaneously whole identical time-frequency resources of antenna use at antenna 1.

Figure 16 illustrated and used on by the 1605 a part of detecting areas that mark, and is used for realizing surveying two kinds of methods of preferred embodiment of the separability of waveform.In the ofdm system as Figure 16 hypothesis, frequency band comprises T/F element 1606, and it is made up of the single OFDM subcarrier in the single OFDM code-element period.In the subcarrier separability type that interweaves, give 4 SS (perhaps may be 4 transmitting antennas on the single SS) with 1620 assignments of identical time-frequency resources, and some element 1606 of time-frequency resources is assigned to SS transmitter #1 (1601), some is assigned to SS transmitter #2 (1602), some is assigned to SS transmitter #3 (1603), and some is assigned to SS transmitter #4 (1604).Because different elements 1606 is assigned to different SS transmitters, the OFDM sub-carrier set merging that probe transmission has taken different (non-intersect) is a quadrature therefore, so can realize separability at BS receiver place.

For sequence orthogonality type method illustrated in fig. 16,4 SS transmitters (1611～1614) are in identical set of subcarriers emission.SS transmitter #1 uses sequence 1 (1611), and SS transmitter #2 uses sequence 2 (1612), and SS transmitter #3 uses sequence 3 (1613), and SS transmitter #4 uses sequence 4 (1614).Have suitable cross correlation properties by means of sequence 1611,1612,1613 and 1614, realized separability at the BS place.

Should be noted that in Figure 16 different SS transmitters can all be positioned on the identical SS, perhaps can be positioned on the different SS, perhaps is positioned in the combination of single antenna SS and a plurality of antenna SS.

As explained above, the present invention makes a plurality of SS carry out channel detection on identical time-frequency resources.In a preferred embodiment, should survey a plurality of SS, for example during two SS, BS will format first message and this first message will be transmitted into a SS in identical DL frame, format second message and this second message is transmitted into the 2nd SS, wherein the first and second message assignments the identical time-frequency resources in the UL detecting area, but to the first and second SS assignments different waveforms.In the use literary composition describe preferred detection waveform designation method the time, to the identical separability pattern of the first and second SS assignments, but the different separability parameter of assignment.

To a plurality of SS transmitters (on identical or different SS), when for example two identical time-frequency resources of SS assignment are used to survey, BS will be received from the synthetic or summation of first and second detectable signals that first and second SS launch in the time-frequency resources of institute's assignment.BS determines to respond about the local channel at least of each first and second SS from the synthetic detectable signal that receives then.This is by to the separable waveform of SS assignment with handle the composite signal received so that channel response separates (for example, by utilizing the advantage of disjoint subcarrier or cross correlation properties) realizes.After obtaining channel response, BS can customize the characteristic at the follow-up emission of at least the one SS based on the response of local channel at least of a SS, so that the closed loop transmission at SS to be provided.

Be used for send channel probe message and the device that is used for the emission detection signal

Figure 17 is the block diagram of the device in the source communication unit, and it comprises: the unit 1700 and the unit 1710 of emission characteristics so that closed loop transmission to be provided that is used to customize at the target transmitter unit that are used for the send channel probe message.The unit 1700 that is used for the send channel probe message is formed by reserving unit 1701, probe message unit 1702 and transmitter unit 1703.Reserve unit 1701 and dynamically reserve the T/F part of frame, as the detecting area that is used for channel detection.Probe message unit 1702 connects with reserving unit 1701, and generate the channel detection assignment message, and this channel detection assignment message has been specified time-frequency resources in the detecting area and detection waveform to be used.Transmitter unit 1703 can be operated and be used for connecting with probe message unit 1702, and send channel is surveyed assignment message.Be used to customize at the unit 1710 of the emission characteristics of object element and form by receiver unit 1704, channel response unit 1705 and signal customization units 1706.Receiver unit 1704 is received in the time-frequency resources of assignment the detectable signal from the object element emission.Channel response unit 1705 connects with receiver unit 1704, and is determined to the small part channel response from the detectable signal that receives.Signal customization units 1706 cochannel response units 1705 and transmitter unit 1703 connect, and based on this local channel response at least, customization is at the occurrence features of object element.

Figure 18 is the block diagram of the device that is used for the emission detection signal 1800 in the target communication unit, and described device 1800 is made up of receiver unit 1801, probe message decoding unit 1802 and transmitter unit 1803.The channel detection assignment message that receiver unit 1801 receives from source communication unit.Probe message decoding unit 1802 connects with receiver unit 1801, and determines from surveying assignment message: time-frequency resources the frame and detectable signal, and to be used for the emission detection signal.Transmitter unit 1803 connects with probe message decoding unit 1802, and emission detection signal in the time-frequency resources of the institute's assignment in frame.

Message format in the preferred embodiment

Be that this system uses DL and UL mapping about the detailed description as the preferred message form of the system of IEEE 802.16 below, with assigned resources in DL frame and UL frame respectively.Should be noted that the most of acronym that uses in these chapters and sections defines in IEEE 802.16 series of specifications.In UL-MAP (UL control channel), BS can utilize UL_Sounding_Zone_Presence_IE () emission UIUC=15, to point out the distribution of the UL detecting area in frame to whole SS.BS can be according to the UL-MAP message UL_Uncoupled_Sounding_IE () of expansion or the DL-MAP message DL-MAP_Coupled_Sounding_IE () of expansion, the one or more OFDMA code elements place emission detection signal of order SS in detecting area.

Owing to only can specify in the relative position of surveying code element in the detecting area, so the definition of the detecting area among the UL_Sounding_Zone_Presence_IE () makes it be used for more effectively specifying out SS will use this (one or more) detectable signal to send detectable signal to (one or more) detection code element subsequently.In addition, in order to point out definitely to survey symbol offset,, need in each UL_Sounding_Zone_Presence_IE (), use the field of 10 bits at each SS to be detected.

Grammer	Size	Note
			UL_Sounding_Zone_Allocation_IE(){
The UIUC of expansion	4 bits	0x03
			Detecting area length	3 bits	The detecting area duration (up to 8 OFDMA code elements)
The OFDMA symbol offset	10 bits	The start element of detecting area
			}

Comprise therein among the UL_Uncoupled_Sounding_IE () of CID, specific to the probe instructions of SS from the base station to SS.It is the UL_Sounding_Zone_Presence_IE () of target that the definition of detecting area is arranged in whole SS.Specific to the message UL_Uncoupled_Sounding_IE () of SS instruction SS one or more specific code element place emission (one or more) specific detectable signal in detecting area, and instruction SS takies and is used for these and surveys each (one or more) specific frequency band of code elements.In this case, look-in frequency distributes and to be independent of among (non-being coupled in) DL-MAP at the existence of any DL data assignment of SS or not to exist.

Grammer	Size	Note
			UL_Uncoupled_Sounding_IE(){
The UIUC of expansion	4 bits	0x04
			CID	16 bits
Num_used_symbols	3 bits	The number of the detection code element that this SS uses, from 1 (bit " 000 ") to 2 3=8 (bit " 111 ")
			For(i＝0；i＜Num_used_symbols；i++){
Survey symbol index	3 bits	Symbol index in the detecting area, from 1 (bit " 000 ") to 2 3=8 (bit " 111 ")
			Start frequency band	5 bits (or 6 bits)	Come from the individual band in 32 (or 48)
The band number	5 bits (or 6 bits)	Employed adjacent strip
			The detection sequence index	2 bits	Sequence index among predefined 4 member groups (the pre-defined some groups that in different sectors, use)
The separability sign	1 bit	0: the whole subcarriers in the band of detection institute assignment; 1: survey the subcarrier of being selected
			The length of separability parameter (" L ")	3 bits	Define the length of next field, it varies to 2 from 1 (bit " 000 ") 3=8 (bit " 111 ")
if(Separability?flag＝0){
			Separability parameter (circulation time shift index)	Variable-length	Make the multiple (from 0 to 2 of time domain code element displacement CP length circularly L-1)
}
			Else?{
Separability parameter (selecting skew)	Variable-length	Survey 2 of subcarrier about first LRelative start offset position in the individual possible position
			}
Many antennas detection mode	1 bit	0: survey first antenna; 1: survey whole antennas, use sequence defined above as about the initial displacement of first antenna or select skew, and for each other antenna, by remaining displacement or select skew and come stepping
			}

Probe instructions specific to SS can also be transmitted into SS from BS as the part of DL-MAP information.Following DL-MAP_Coupled_Sounding_IE () should not be used, unless UL_Sounding_Zone_Presence_IE () appears in the identical frame.DL-MAP_Coupled_Sounding_IE () order SS uses specific detectable signal, the one or more specific code element place emission in detecting area.In this case, distribute the frequency band of detection information that obtains (therefore being called as " coupling is surveyed ") from DL.

Grammer	Size	Note
			DL-MAP_Coupled_Sounding_IE(){
The DIUC of expansion	4 bits
			If(INC_CID＝＝1){
N_CID	8 bits
			For(n＝0；n＜N_CID；n++){
CID	16 bits
			}
}
			The OFDMA symbol offset	10 bits
Give channels offset	5 bits
			Promote	3 bits
The No.OFDMA code element	9 bits
			No. subchannel	5 bits
Num_sounding_symbols	3 bits	The number of the detection code element that this SS uses
			for (I＝0；I＜Num_sounding_symbols；I++){
Survey symbol index	3 bits	Symbol index in the detecting area
			The detection sequence index	2 bits	Sequence index among predefined 4 member groups (the pre-defined some groups that in different sectors, use)
The separability sign	1 bit	0: the whole subcarriers in the band of detection institute assignment; 1: survey the subcarrier of selecting
			The length of separability parameter (L)	3 bits	Define the length of next field, it varies to 2 from 1 (bit " 000 ") 3=8 (bit " 111 ")
If(Separability?flag＝0){
			Separability parameter (circulation time shift index)	Variable-length	Make the multiple (from 0 to 2 of time domain code element displacement CP length circularly L-1)
}
			Else{
Separability parameter (selecting skew)	Variable-length	Survey 2 of subcarrier about first LRelative start offset position in the individual possible position
			}
Many antennas detection mode	1 bit	0: survey first antenna; 1: survey whole antennas, use sequence defined above as about the initial displacement of first antenna or select skew, and for each other antenna, by remaining displacement or select skew and come stepping
			}

Frequency band of detection information also can non-ly be coupled in DL distributes, and it does not illustrate herein.In addition, non-coupling and coupling probe message can append to existing 802.16d downlinlc message, to realize certain saving of message overhead, shown in two following tables.

Grammer	Size	Note
			MIMO_DL_Basic-Uncoupled_Sounding_IE ()
The DIUC of expansion	4 bits	0x05
			Length	4 bits	Byte length
Num_Region	4 bits
			For (i=0; I＜Num_Region; I++)
The OFDMA symbol offset	10 bits
			Subchannel offset	5 bits
Promote	3 bits
			The No.OFDMA code element	9 bits
No. subchannel	5 bits
			Matrix_indicator	2 bits	STC matrix (referring to 8.4.8.4)
		The diversity mode of pointing out among the up-to-date TD_Zone_IE () of Transmit_diversity=.if (Transmit_Diversity=01) { 00=matrix A 01=matrix B 10-11=reservation } elseif (Transmit_Diversity=10) { 00=matrix A 01=matrix B 10=Matrix C 11=reservation }
			The closed-loop MIMO sign	2 bits	00=open loop 01=closed loop TxAA (meaning Num_layer=1 subsequently) 10=closed-loop MIMO 11=closed loop SDMA (SS makes a response accordingly by using different reception and channel estimation method)
Num_layer	2 bits
			For (j=0; J＜Num_layer; J++)
If (INC_CID==1)
			CID	16 bits
}

Layer_index	2 bits
			}
}
			Num_used_symbols	3 bits	The number of the detection code element that this SS uses, from 1 (bit " 000 ") to 2 3=8 (bit " 111 ")
for(i＝0；i＜Num_used_symbols；i++){
			Survey symbol index	3 bits	Symbol index in the detecting area, from 1 (bit " 000 ") to 2 3=8 (bit " 111 ")
Start frequency band	5 bits (or 6 bits)	Come from the individual band in 32 (or 48)
			The band number	5 bits (or 6 bits)	Employed adjacent strip
The detection sequence index	2 bits	Sequence index among predefined 4 member groups (the pre-defined some groups that in different sectors, use)
			The separability sign	1 bit	0: the whole subcarriers in the band of detection assignment; 1: survey the subcarrier of selecting
The length of separability parameter (" L ")	3 bits	Define the length of next field, it varies to 2 from 1 (bit " 000 ") 3=8 (bit " 111 ")
			if(Separability?flag＝0){
Separability parameter (circulation time shift index)	Variable-length	Make the multiple (from 0 to 2 of time domain code element displacement CP length circularly L-1)
			}
Else{
			Separability parameter (selecting skew)	Variable-length	Survey 2 of subcarrier about first LRelative start offset position in the individual possible position
}
			Many antennas detection mode	1 bit	0: survey first antenna; 1: survey whole antennas, use sequence defined above as about the initial displacement of first antenna or select skew, and for each other antenna, by remaining displacement or select skew and come stepping
}

Grammer	Size	Note
			MIMO_DL_Basic-Uncoupled_Sounding_IE ()		[from the existing field among the MIMO_ DL_Basic_IE () that is illustrated as red acceptable contribution 80rl]
The DIUC of expansion	4 bits	0x05
			Length	4 bits	Byte length
Num_Region	4 bits
			For (i=0; I＜Num_Region; I++)
The OFDMA symbol offset	10 bits
			Subchannel offset	5 bits
Promote	3 bits
			The No.OFDMA code element	9 bits
No. subchannel	5 bits
			Matrix_indicator	2 bits	STC matrix (referring to 8.4.8.4)
		The diversity mode of pointing out among the up-to-date TD_Zone_IE () of Transmit_diversity=.if (Transmi_Diversity=01) { 00=matrix A 01=matrix B 10-11=reservation } elseif (Transmit_Diversity=10) { 00=matrix A 01=matrix B 10=Matrix C 11=reservation }
			The closed-loop MIMO sign	2 bits	00=open loop 01=closed loop TxAA (meaning Num_layer=1 subsequently) 10=closed-loop MIMO 11=closed loop SDMA (SS makes a response accordingly by using different reception and channel estimation method)
Num_layer	2 bits
			For (j=0; J＜Num_layer; J++)

if(INC_CID＝＝1){
			CID	16 bits
}
			Layer_index	2 bits
}
			}
Num_used_symbols	3 bits	The number of the detection code element that this SS uses, from 1 (bit " 000 ") to 2 3=8 (bit " 111 ")
			for(i＝0；i＜Num_used_symbols；i++){
Survey symbol index	3 bits	Symbol index in the detecting area, from 1 (bit " 000 ") to 2 3=8 (bit " 111 ")
			The detection sequence index	2 bits	Sequence index among predefined 4 member groups (the pre-defined some groups that in different sectors, use)
The separability sign	1 bit	0: the whole subcarriers in the band of detection institute assignment; 1: survey the subcarrier of selecting
			The length of separability parameter (" L ")	3 bits	Define the length of next field, it varies to 2 from 1 (bit " 000 ") 3=8 (bit " 111 ")
If(Separability?flag＝0){
			Separability parameter (circulation time shift index)	Variable-length	Make the multiple (from 0 to 2 of time domain code element displacement CP length circularly L-1)
}
			Else{
Separability parameter (selecting skew)	Variable-length	Survey 2 of subcarrier about first LRelative start offset position in the individual possible position
			}
Many antennas detection mode	1 bit	0: survey first antenna; 1: survey whole antennas, use sequence defined above as about the initial displacement of first antenna or select skew, and for each other antenna, by remaining displacement or select skew and come stepping
			}

About surveying the extraneous information of waveform

Surveying waveform is selected as making BS can estimate uplink channel about the frequency band of being paid close attention to.Because the limited transmitting power of mobile device, particularly handheld device, the link budget that improves up link is important, it can be realized by different means, such as, by only on less bandwidth or on the subcarrier of being selected, launching, allow power ascension.Another important means is to improve the PAPR of the detection waveform of OFDM style.As the good candidate of surveying waveform is that (it is non-binary unit amplitude sequence to Generalized C hirp Like for Generalized Chirp Like, GCL) waveform.For different sequence lengths, there are many GCL sequences (being called as " class ").In the time of on being applied in the OFDM subcarrier that evenly separates, if when the time domain discrete time signal is in the Nyquist sample rate definitely, then time-domain signal also has unit amplitude.But because the protection subcarrier that uses in whole practical ofdm systems, time domain waveform is equivalent to after " sinc " pulse shaping filter and carries out over-sampling.PAPR will not have definite unit amplitude as a result, but for any particular length, and a large amount of GCL sequences is still enjoyed low PAPR (typically 3～4dB).

The GCL sequence that is used to survey is expressed as

$S_u\left(k\right)=\exp \{-j2\mathrm{\πu}\frac{k(k+1)}{{2N}_G}\},k=0\·\·\·N_G-1\mathrm{andu}(\text{'}\mathrm{clas}\sin \mathrm{dex}\text{'})=1\·\·\·N_G-1$

(1)

N wherein _GBe the length (be selected as prime number, it is explained in the back) of GCL sequence, and u is called as the class index, it is 1 and N _GBetween the nonzero integer selected.This GCL sequence has following important attribute:

Attribute 1:GCL sequence has constant amplitude, and its N _GPoint DFT also has constant amplitude.

Attribute 2: the GCL sequence of any length has " desirable " circulation auto-correlation (promptly the correlation of cyclic shift version with himself is the delta function)

Attribute 3: when | the relative N of u1-u2|, u1 with u2 _GWhen relatively prime, the absolute value of the Cyclic Cross-Correlation Transform function between any two GCL sequences is constant, and equals

The cross-correlation of whole displacements place (attribute 3) is actually that (that is, make the maximum minimum of the cross-correlation of whole displacements place, it equals about the attainable minimum value of any two sequences with desirable auto-correlation attribute

).When using many potential interference sequences in single sector or many sectors environment, this attribute is important.Cross correlation properties allows interference signal after with required signal correction, expands in the time domain equably.Therefore, will detect required subscriber channel (for example, by " denoising " estimator) more reliably.

The number of surveying the excimer carrier wave in the waveform is not prime number usually.For example, if survey the band with 36 subcarriers, then the length of frequency domain detection sequence is 36.In this case, we propose, and select the minimum prime number (for example, being 37 in example above) greater than Len req, then it are truncated into required length.Alternative is that selection makes its cyclic extension to required length less than the largest prime number (for example, being 31 in example above) of Len req then.When carrying out this modification, only approximate these three attributes that keep still can find that they keep very goodly, particularly when sequence is long.

For any required detection sequence length (L for example _S), as previously mentioned, be to introduce by the sub-carrier subset that sequence only is applied to adjacency owing to used over-sampling effect, this over-sampling effect, PAPR will increase seldom like this.But, can store the sequence class index that has provided best PAPR in advance for each length value.They can be divided into many group (N _Gr, for example 6), and each group is by many sequence class (N _C1, for example 4) form.Therefore, different groups will be assigned to adjacent sector, and each sector can be used one in these classes (sequence) in the group of its assignment.This group assignment is sent to the whole users its service area from the BS sector.In one embodiment, each sector of BS has identification (ID) number.There is the correspondence one by one between group and the id number.Therefore, sequence can be stored by each SS, and can select suitable sequence group based on BS ID by SS.

Although BS will survey the waveform assignment in the mode of quadrature and give SS, wherein only need single sequence, when not having enough orthogonal waveforms, about the N of the assignment in advance of each group for each group _C1Sequence has provided the option that uses more sequence.At least, employed extra sequence will have minimum cross correlation.It should be noted that every pair of sequence, no matter all will have minimum cross correlation properties from identical group or different groups.Should be noted that the PAPR for the best, the GCL sequence stress be sent out the subcarrier (spacing can be 1) that evenly separates.If the excimer carrier wave descends at DC subcarrier place, then should use the corresponding element of GCL sequence, although it can be set to 0 before adopting IFFT.

Except the disjoint subset allocation that will survey subcarrier gives different users guaranteeing the orthogonality, other method is, launches the cyclic shift version of identical sequence, separate users channel by the user by other.For example, the sequence in first user emission (1), and m user launches following sequence:

$S_{\mathrm{um}}\left(k\right)=S_u\left(k\right)e^{-j2\mathrm{\πk}(m-1)L_{\mathrm{CP}}/N},$

(2)

S wherein _u(k) in (1), provide, and N is FFT size (it is 2048), and L _CPIt is circulating prefix-length.

Uplink channel estimation has been discussed herein briefly, has been used to illustrate advantage how to utilize cross correlation properties.Basically, recommend to have the time domain estimator that the self adaptation tap is selected, wherein obtained time domain channel response, and will only comprise the tap that has above the power of noise power certain threshold level.This channel estimator can be suitable for transient state channel latency profile, and when SNR is low and channel when being sparse, it is useful especially.In the situation of medium paramount SNR, owing to have with the similar performance of time domain method, so the MMSE channel estimator also is gratifying.

Being described below of time domain uplink channel estimation device.Suppose that the place, base station is Yn (k) about the frequency domain data of reception antenna n, wherein k is a data subcarrier.Should be noted that Yn (k) will be by forming about the uplink sounding of some users or transmitting antenna.At first, by conjugate multiplication, followingly obtained the noisy communication channel estimation with the GCL sequence:

${\tilde{H}}_n\left(k\right)=Y_n\left(k\right)S_u^{*}\left(k\right)---\left(3\right)$

Below, IFFT transforms to time domain with Noise Estimation by the N point:

${\tilde{h}}_n\left(l\right)=\frac{1}{N}\underset{k=0}{\overset{K-1}{\mathrm{\Σ}}}{\tilde{H}}_n\left(k\right)e^{j2\mathrm{\πlk}/N}0\≤l\≤N-1---\left(4\right)$

Wherein K is a number of surveying subcarrier.N can be selected as greater than K and be the integer of the minimum of 2 power.In the situation of the detection waveform of appointment in (2), the channel of different user (or transmitting antenna) is separable in time domain.The time domain channel that this means user m estimates it is sample (m-1) L of (3) simply _CP～mL _CP-1.Channel estimating when improving low SNR has proposed the tap selection strategy.Tap is selected to mean that simply the time tap that is lower than certain threshold value η is set to 0.Therefore tap is selected to be complementary by attempting making channel estimator postpone profile with the transient power about each user, has improved the channel estimating about sparse relatively channel.Threshold value η=the 3dB that is better than the SNR of estimation is the example of choose reasonable.Suppose that the time domain channel estimation about whole users after the tap selection is denoted as Below, after determining threshold value, will estimate to be designated as h about the time domain channel of user m _{M, n}(l) (wherein, significantly, the channel of user m is simply $h_{m,n}\left(l\right)={\hat{h}}_n((m-1)L+l)(0\≤l\≤L-1)).$ Like this, estimate it is h about the frequency domain channel of user m _{M, n}(l) N point FFT:

$H_{m,n}\left(k\right)=\underset{l=0}{\overset{L-1}{\mathrm{\Σ}}}{h}_{m,n}\left(l\right)e^{-j2\mathrm{\πlk}/N}0\≤k\≤K-1---\left(5\right)$

Person of skill in the art will appreciate that, under prerequisite without departing from the spirit and scope of the present invention, can revise widely, replace and make up at above-described embodiment, and this modification, alternative and assembled scheme should be regarded as in the scope of notion of the present invention.In the scope that purpose is to make this modification, alternative and assembled scheme be covered by appended claims.

Claims (11)

1. one kind is used for making under the hypothesis of channel reciprocity base station (BS) can determine the method for BS-to the channel response of-subscriber station (SS), said method comprising the steps of:

Determine the uplink sounding district in the frame; With

Instruct described SS in described detecting area, to launch specific detectable signals, and specify in each detection symbol interval occupied specific look-in frequency with one or more specific symbol intervals.

2. the method for claim 1, the step in wherein said definite described uplink sounding district may further comprise the steps: determine the one or more OFDM/OFDMA symbol intervals in the following stated frame, that is, described frame is to be used to launch described detectable signal and to be made described BS can determine the channel response between described BS and the described SS by SS.

3. the method for claim 2, wherein saidly determine that the step in described uplink sounding district may further comprise the steps: determine non-overlapped frequency band, wherein each frequency band comprises a plurality of continuous OFDM/OFDMA subcarriers.

4. the method for claim 2, wherein saidly determine that the step in described uplink sounding district may further comprise the steps: determine non-overlapped frequency band, wherein each frequency band comprises 18 continuous OFDM/OFDMA subcarriers.

5. it is further comprising the steps of to the process of claim 1 wherein that the described SS of described instruction launches the step of described particular probe signal: instruct described SS described detectable signal of emission on continuous sub-carriers or the subcarrier selected.

6. base station comprises:

Reserve the unit, be used for dynamically reserving the T/F part of frame, as the detecting area that is used for channel detection;

The probe message unit is used to generate the channel detection assignment message, and described channel detection assignment message has been specified time-frequency resources in the described detecting area and detection waveform to be used; With

Transmitter is used to launch described channel detection assignment message.

7. the base station of claim 6 further comprises:

Receiver unit is used for receiving the detectable signal of described subscriber station in the described T/F part emission of described frame;

The channel response unit is used for being determined to the small part channel response from described detectable signal; With

The signal customization units is used for based on the described response of local channel at least, and customization is at the transmission characteristic of described subscriber station, so that the closed loop transmission at described target communication unit to be provided.

8. the base station of claim 6, further comprise: the identification number that subscriber station is known, and wherein said subscriber station is determined armed described detection waveform from described at least identification of base stations number, separability pattern, separability parameter and detection sequence index.

9. the base station of claim 6, wherein said T/F partly comprises: in integer number OFDM (Orthodoxy Frequency Division Multiplex) code-element period of integer number OFDM subcarrier.

10. the base station of claim 6, wherein said channel detection assignment message further comprises: many antennas detection mode is used to point out the set of one or more antennas of being used to survey and about the detection waveform of each described antenna.

11. the base station of claim 6, wherein said channel detection assignment message further comprises: the separability pattern, it has pointed out the described subscriber station that will launch on each subcarrier in described temporal frequency resource.

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