CN101034931B - Radio forwarding communication system and method - Google Patents

Abstract

A wireless relay communication system, including a base station BS, a relay station RS and a user terminal; the RS is respectively provided with an interface for communicating with the BS and the user terminal, and the RS includes a frequency division duplex FDD wireless transceiver and a network coding technology-based The wireless link layer processing unit; both the BS and the user terminal include an FDD wireless transceiver and a wireless link layer processing unit based on network decoding technology; the FDD wireless transmitter physical layer contained in the FDD wireless transceiver of the RS, BS and user terminal The processing unit and the FDD wireless receiver physical layer processing unit; the FDD wireless transmitter physical layer processing unit of the RS and the FDD wireless receiver physical layer processing unit are respectively connected with the FDD wireless receiver physical layer processing unit and the FDD wireless receiver in the BS and the user terminal Transmitter physical layer processing unit corresponds. In addition, the present invention also includes a transfer communication method based on the system, which can effectively increase the transfer throughput.

Description

Wireless relay communication system and method

technical field

The invention relates to the technical field of wireless communication, in particular to a network coding-based Orthogonal Frequency Division Multiple Access (OFDMA) wireless relay communication system and method.

Background technique

lEEE802.16 is the first broadband wireless access standard, and there are two main versions: the broadband fixed wireless access version of the 802.16 standard, "802.16-2004" and the broadband mobile wireless access version of the 802.16 standard, "802.16e". 802.16-2004 defines only two types of network elements, BS and SS; 802.16e also defines only two types of network elements, BS and MSS. At present, 802.16Multihop Relay SG (802.16 Multihop Relay Research Group) only proposed the concept of WiMAX relay station (RS), one of the important functions is to serve as the relay between BS and SS/MSS, to expand the coverage of BS or to increase the number of subscriber stations throughput. In order to support RS, what modifications and enhancements should be made to the physical layer frame structures of BS, RS and MS/SS are still new topics.

In a channel (Channel) of Orthogonal Frequency Division Multiplex (OFDM) or Orthogonal Frequency Division Multiplex Access (OFDMA) system (such as 802.16 system), its OFDM or OFDMA symbols are composed of subcarriers (Subcarrier), and the number of subcarriers determines the number of Fast Fourier Transform (FFT) points. Subcarriers constituting a subchannel (Subchannel) may or may not be adjacent, and FIG. 1 is an example of adjacent subcarriers. There are several types of subcarriers according to the type of data transmitted:

1. Data subcarriers: subcarriers used to transmit data;

2. Pilot subcarrier: subcarrier used for pilot frequency;

3. Empty subcarriers: subcarriers that are not used to transmit any number, including guard bands (Guard Band) and DC subcarriers (DC Subcarrier).

In OFDM or OFDMA systems, different users divide the uplink FFT space, and each user transmits on one or more sub-channels. The division of sub-channels is an FDMA method. All effective sub-carriers are divided into several sub-carrier sets, and each sub-carrier set is called a sub-channel (subchannel). There are three main methods for dividing sub-channels:

The first is to divide the carrier into continuous groups, which is the simplest to implement, and the interference of adjacent sub-channels is small, but the obtained frequency diversity effect is poor.

The second is that carriers of different sub-channels are interleaved in a regular manner. This frequency diversity effect is better, but the system is more sensitive to inter-sub-channel interference.

The third is an improvement on the second, that is, carriers of different sub-channels are interleaved in a pseudo-random manner, and different base stations use different sequence change codes to reduce interference between base stations.

In the 802.16 standard, for the licensed frequency band, the duplex mode can be FDD and TDD, and the SS of the FDD mode can be half-duplex FDD, but for the license-free frequency band, the duplex mode can only be TDD. The 802.16OFDMA (or SOFDMA) frame structure under TDD is shown in Figure 2. In 802.16 OFDMA (or SOFDMA) mode, a physical layer (PHY) burst in OFDMA (or SOFDMA) is assigned a group of adjacent sub-channels and a group of OFDMA symbols (symbol).

The data transmitted on the physical channel is transmitted in the format of frame (Frame). Each frame includes a downlink subframe (DL subframe, abbreviated as DL in FIG. 2 ) and an uplink subframe (UL subframe, abbreviated as UL in FIG. 2 ). In TDD mode, the downlink subframe DL is transmitted first, followed by the uplink subframe UL. A burst can be assigned to an SS/MSS (or a group of users) in the uplink, and can be sent to the SS/MSS by the BS as a sending unit in the downlink. The initial access ranging Ranging, periodic ranging Ranging, and bandwidth request of the uplink SS are all performed through the Ranging subchannel. The downlink subframe has a preamble (preamble) at the beginning, which is used for physical synchronization; followed by a frame control header (FCH), which is used to specify the profile and length of one or more downlink Bursts immediately after the FCH. Then the downlink mapping table DL-MAP is used to indicate the subchannel and OFDMA symbol position and usage method (profile) of each downlink burst, and the uplink mapping table (UL-MAP) is used to indicate the subchannel and OFDMA symbol position and How to use (profile). In a TDD system, TTG and RTG will be inserted when the uplink and downlink subframes alternate, so as to allow a period of time for the BS to complete the alternate transmission and reception.

The difference between the 802.16OFDMA (or SOFDMA) frame structure under FDD and the 802.16OFDMA (or SOFDMA) frame structure under TDD is that uplink subframes and downlink subframes are sent on different frequencies, and there is no need to set TTG and RTG.

Network coding technology was first proposed by Professor Li Shuoyan. Network coding can be divided into linear network coding and convolutional network coding. The specific principles can be found in IEEE papers: Li, Yeung & Cai, "LinearNetwork Coding," IEEE Trans.Info.Thy, Feb .2003.

In the existing relay technology shown in Figure 3, RS communicates with BS and MS/SS using FDD single-carrier mode, MS/SS performs wireless relay access to BS through RS, and RS accesses BS as an MS/SS. DL _BS is the downlink subframe of the BS physical layer frame, from BS to SS/MS _BS or RS, UL _BS is the uplink subframe of the BS physical layer frame, from SS/MS _BS or RS to BS; DL _RS is RS The downlink subframe of the physical layer frame is from the BS to the SS/MS _RS or RS, and the UL _RS is the uplink subframe of the physical layer frame of the RS, from the SS/MS _RS or RS to the BS.

The base station and the user station need 4 time slots to exchange data packets through the relay station: time slot 1, BS to RS; time slot 2, MS to RS; time slot 3, RS to MS; time slot 4, RS to BS.

In the prior art, each transit data has to be sent twice, so the throughput of the transit system is low, and the network capacity is limited, which affects the scale and cost of the network.

In addition, in the FDD mode, there is mutual interference between the base station, the relay station and the user station in the communication of the network system.

Contents of the invention

The object of the present invention is to provide a relay communication system capable of maximally increasing the relay throughput, and a relay communication method adopted by the system.

A wireless relay communication system of the present invention is a network coding-based orthogonal frequency division multiplexing access wireless relay communication system, including a base station BS, a relay station RS, and a user terminal. Carry out wireless communication; the RS provides interfaces for communicating with the BS and the user terminal respectively, and the RS includes a frequency division duplex FDD wireless transceiver and a wireless link layer processing unit based on network coding technology; both the BS and the user terminal Including FDD wireless transceiver and wireless link layer processing unit based on network decoding technology; FDD wireless transceiver of RS, BS and user terminal includes FDD wireless transmitter physical layer processing unit and FDD wireless receiver physical layer processing unit; RS’s The physical layer processing unit of the FDD wireless transmitter corresponds to the physical layer processing unit of the FDD wireless receiver in the BS and the user terminal respectively; the physical layer processing unit of the FDD wireless receiver of the RS corresponds to the physical layer processing unit of the FDD transmitter in the BS and the user terminal respectively Unit corresponds.

A wireless relay communication method of the present invention comprises the steps of:

A. Set the downlink middle rotor channel and the uplink middle rotor channel respectively in the downlink subframe and the uplink subframe of the BS physical layer frame structure, which are respectively used to define the BS downlink middle rotor channel and OFDMA symbol combination transmitted to the RS by the BS, and Combination of the BS uplink mid-rotor channel and OFDMA symbols transmitted by the RS to the BS; the downlink mid-rotor channel is set in the uplink subframe of the RS physical layer frame structure, which is used to define the mid-rotor channel and OFDMA of the RS receiving the downlink mid-rotor channel of the BS Symbol combination, set the uplink mid-rotor channel in the downlink subframe of the RS physical layer frame structure, used to define the uplink mid-rotor channel and OFDMA symbol combination of the RS receiving the BS;

B. Between the BS, the RS and the user terminal, the OFDMA wireless relay communication is performed in the FDD mode based on the uplink and downlink physical layer frames of the BS and the RS.

The present invention maximizes the throughput of the transit system by introducing the mechanism of combining OFDMA (or OFDM sub-channel) technology and network coding technology, which can increase the throughput by 25% in theory, effectively improving the defects of the prior art .

The OFDMA (or OFDM sub-channel) physical layer frame structure defined by the present invention based on the characteristics of network coding technology effectively supports OFDMA (or OFDM sub-channel) wireless transfer function, that is, MS/SS can perform wireless transfer access to BS through RS .

Can avoid the self-interference of "RS to SS/MS _BS ", "BS to SS/MS _RS ", "SS/MS _BS to RS", "SS/MS _RS to BS" and "RS to RS" in the prior art ; Can avoid interference from "RS to SS/MS _RS ";, Can avoid "SS/MS _BS to BS", "SS/MS _RS to RS", "SS/MS _RS to SS/MS _BS ", "SS/MS MS _BS to SS/MS _RS ” interference.

Description of drawings

Fig. 1 is a schematic diagram of adjacent subcarriers of OFDMA symbols.

FIG. 2 is a schematic diagram of a frame structure based on 802.16 OFDMA (or SOFDMA) under TDD.

FIG. 3 is a schematic diagram of a transfer mode of an existing wireless transfer communication system.

FIG. 4 is an advanced relay system of OFDM (or OFDMA) based on network coding technology of the present invention.

Fig. 5 is the OFDM (or OFDMA) simplified relay system based on network coding technology of the present invention.

FIG. 6 is a schematic diagram of a co-channel interference mode based on network system communication under FDD.

FIG. 7 is a schematic structural diagram of the network coding-based transfer system of the present invention.

FIG. 8 is a schematic diagram of the physical layer frame structure of the BS and the RS in the advanced relay mode of the present invention.

FIG. 9 is a schematic diagram of the physical layer frame structure of the BS and the RS in the simplified transit mode of the present invention.

Detailed ways

As shown in Fig. 4, the present invention is based on OFDM (or OFDMA) advanced relay system model of network coding technology. Among them, RS communicates with BS and MS/SS using FDD/OFDMA (or OFDM sub-channel) mode, BS downlink and RS uplink use frequency f1, BS uplink and RS downlink use frequency f2, and RS only needs a set of FDD wireless transceivers. The MS/SS performs wireless relay access to the BS through the RS, and the RS accesses the BS as an MS/SS. DL _BS is the downlink subframe of the BS physical layer frame, from BS to SS/MS _BS or RS, UL _BS is the uplink subframe of the BS physical layer frame, from SS/MS _BS or RS to BS; DL _RS is RS The downlink subframe of the physical layer frame is from the BS to the SS/MS _RS or RS, and the UL _RS is the uplink subframe of the physical layer frame of the RS, from the SS/MS _RS or RS to the BS.

The base station and the subscriber station only need 2 time slots to exchange data packets through the relay station: in time slot 1, the packet A of the BS and the packet B of the MS are respectively sent to the RS through different OFDM sub-channels, the BS buffers the packet A, and the MS buffers the packet B; RS performs network coding on packet A of BS and packet B of MS, for example, directly performs "exclusive OR" operation on a bit basis to obtain In time slot 2, the RS will complete the network encoded packet Do broadcast and send to BS and MS at the same time; BS does network decoding, and caches packet A and network encoded packets Do the "exclusive OR" operation to get the package B of MS, that is $A\⊕(A\⊕B)=B;$ MS does network decoding, and will cache packet B and network encoded packets Do the "exclusive OR" operation to get the package A of BS, that is $B\⊕(A\⊕B)=A.$

As shown in FIG. 5, the RS, BS, and MS/SS simplified relay communication mode of the present invention. Among them, the downlink broadcast burst (Broadcast Burst) of DLBS, such as Preamble, FCH, DL-MAP, UL-MAP, is sent directly by BS to MS/SS, without RS relay; MS/SS initial access ranging Ranging , Periodic ranging Ranging, bandwidth request through the ranging subchannel RangingSubchannel of the ULBS, directly sent by the MS/SS to the BS, without relaying through the RS; for other bursts of the DLBS downlink, such as data packets or DL-MAP, Messages other than UL-MAP cannot be directly sent from BS to MS/SS, but must be relayed through RS; other uplink bursts of ULBS, such as initial access ranging Ranging, periodic ranging Ranging, Except for the bandwidth request message, it cannot be directly sent to the BS by the MS/SS, but must be relayed by the RS.

As shown in FIG. 7, a transit communication system based on network coding of the present invention. in,

Base stations include:

Transmission processing unit (wired transmission processing unit in the figure): It can establish communication with upper-level equipment (such as base station controller) or with a group of base station equipment respectively, and communicate with upper-level equipment or each base station equipment interact;

FDD wireless transceiver: used for wireless communication with RS or SS/MS in FDD mode, composed of FDD wireless transmitter physical layer processing unit, FDD wireless receiver physical layer processing unit and wireless data link layer processing unit.

FDD wireless transmitter physical layer processing unit (frequency f1): FDD wireless receiver 1 physical layer processing unit in the wireless data link layer and SS/MS that can communicate with it or the FDD wireless receiver physical layer in RS The processing unit performs wireless communication; for the simplified transfer mode, this unit adopts channel coding and modulation with higher reliability than other transmitted data for the downlink subframe head broadcast of DL _BS (such as Preamble, FCH, DL-MAP, UL-MAP) mode (such as binary phase shift keying BPSK), or use a higher transmission power than other transmitted data, and send it directly from the BS to the MS/SS without relaying through the RS;

FDD wireless receiver physical layer processing unit (frequency f2): FDD wireless transmitter 1 physical layer processing unit in the wireless data link layer and SS/MS that can communicate with it or the FDD wireless transmitter physical layer in RS The processing unit communicates wirelessly;

Wireless data link layer processing unit: For the data from the physical layer processing unit of the FDD wireless receiver, after receiving and processing the data of the wireless data link layer and decoding the network, forward it to the wired transmission processing unit; for the data from the wired transmission processing unit After the data is sent and processed in the wireless data link layer, it is forwarded to the physical layer processing unit of the FDD wireless transmitter.

User stations include:

FDD wireless transceivers 1 and 2: used for wireless communication with BS or RS in FDD mode, composed of physical layer processing units of FDD wireless transmitters 1 and 2, physical layer processing units of FDD wireless receivers 1 and 2 and FDD wireless Transceivers 1 and 2 are composed of wireless data link layer processing units.

FDD wireless transmitter 1 physical layer processing unit (frequency is f2): carry out wireless communication with FDD wireless transceiver 1 and 2 data link layers and the FDD wireless receiver physical layer processing unit in the BS that can communicate with it; Transit mode, the unit performs uplink random access (RandomAccess) slots (or contention slots) for UL _BS , such as initial Ranging contention slots and bandwidth request contention slots, or initial access of MS/SS Ranging, Periodic Ranging, and Bandwidth Request Ranging Subchannel through the UL _BS ’s ranging subchannel, using channel coding and modulation methods that are more reliable than other transmitted data (such as binary phase shift keying BPSK), or using The transmission power is higher than other transmission data, which is directly sent from MS/SS to BS without relaying through RS;

FDD wireless transmitter 2 physical layer processing unit (frequency is f1): perform wireless communication with FDD wireless transceiver 1 and 2 data link layers and the FDD wireless receiver physical layer processing unit in the RS that can communicate with it;

FDD wireless receiver 1 physical layer processing unit (frequency f1): perform wireless communication with the wireless data link layer and the FDD wireless transmitter physical layer processing unit in the BS that can communicate with it;

FDD wireless receiver 2 physical layer processing unit (frequency is f2): perform wireless communication with the wireless data link layer and the wireless transmitter physical layer processing unit in the RS that can communicate with it;

Wireless data link layer processing unit: For the data from the FDD wireless receiver 1 and/or 2 physical layer processing unit, after the data receiving processing and network decoding of the wireless data link layer, forward it to the user; the data from the user , after performing data transmission processing on the wireless data link layer, and then forwarding to the FDD wireless transmitter 1 and/or 2 physical layer processing units.

Transit stations include:

FDD wireless transceiver: used for wireless communication with SS/MS or BS in FDD mode, composed of FDD wireless transmitter physical layer processing unit, FDD wireless receiver physical layer processing unit and wireless data link layer processing unit.

FDD wireless transmitter physical layer processing unit: perform wireless communication with the wireless data link layer and the FDD wireless receiver 2 physical layer processing unit or BS FDD wireless receiver physical layer processing unit in the SS/MS that can communicate with it;

FDD wireless receiver physical layer processing unit: perform wireless communication with the wireless data link layer and the physical layer processing unit of the FDD wireless transmitter 2 in the SS/MS or the FDD wireless transmitter physical layer processing unit in the BS that can communicate with it;

Wireless data link layer processing unit: For the data from the FDD wireless receiver physical layer processing unit, perform data receiving processing, network coding and sending processing on the wireless data link layer, and then forward it to the FDD wireless transmitter physical layer processing unit.

In the physical layer frame structure of the BS and RS in the simplified transfer mode of the present invention as shown in FIG. 8:

In the downlink subframe (DL _BS ) with the frequency of f1 in the physical layer frame structure of the BS, define "DL RelaySubchannel (downlink middle relay channel)", which is used to define the BS downlink middle relay channel and OFDMA symbols transmitted by the BS to the RS Combination; in the case of multiple RSs, different downlink intermediate rotor channels are defined for different RSs;

In the uplink subframe (UL _RS ) with the frequency of f1 in the physical layer frame structure of RS, define "DL RelaySubchannel (downlink intermediate subchannel)", which is used to define the intermediate subchannel and OFDMA symbol combination of RS receiving DL RelaySubchannel of BS ; For the case of multiple RSs, different RSs only receive the relay data of the BS in the corresponding downlink middle rotor channel, and other sub-channels do not arrange relay reception;

In the uplink subframe (UL _BS ) with the frequency f2 of the physical layer frame structure of the BS, define "UL RelaySubchannel (uplink intermediate subchannel)", which is used to define the BS uplink intermediate subchannel and OFDMA symbols transmitted by the RS to the BS Combination; in the case of multiple RSs, different uplink intermediate rotor channels are defined for different RSs;

TDM technology is adopted in the downlink subframe (DL _RS ) of the physical layer frame structure of the RS with the frequency f2, and "UL Relay Subchannel (uplink intermediate channel)" is added to define the intermediate channel of the RS receiving the UL Relay Subchannel of the BS Combined with OFDMA symbols; in the case of multiple RSs, different RSs only transmit the relay data of the BS in the corresponding uplink middle rotor channel, and other sub-channels cannot be arranged for relay transmission;

During BS UL Relay Subchannel, SS/MS _BS does not arrange any transmission subchannel and OFDMA symbol combination to avoid "SS/MS _BS to BS"interference; during BS DL Relay Subchannel, SS/MS _RS does not arrange any transmission Combination of sub-channels and OFDMA symbols to avoid "SS/MS _RS to RS"interference;

Define "RelayRanging Subchannel (relay ranging subchannel, abbreviated as RRS)" in the uplink subframe (UL _BS ) with the frequency of f2 in the physical layer frame structure of the BS, and define the initial access ranging Ranging and period for RS BS relay ranging receiving subchannel and OFDMA symbol combination for periodic ranging Ranging and bandwidth request; the relay ranging subchannel RRS can also be used as the initial access ranging Ranging, periodic ranging Ranging, and bandwidth request of SS/MS _BS Used for ranging sub-channels. Define "Relay Ranging TXSubchannel (relay ranging transmission subchannel, abbreviated as RRS TX)" in the downlink subframe (DL _RS ) of the physical layer frame structure of the RS with a frequency of f2, which is used to define the initial access ranging of the RS Ranging, periodic ranging Ranging, RS relay ranging transmission subchannel and OFDMA symbol combination for bandwidth request. The time-frequency relationship between the Relay Ranging Subchannel of the BS and the RelayRanging TX Subchannel of the RS must correspond one-to-one and be strictly synchronized.

In the downlink subframe of the BS physical layer frame structure or the uplink subframe of the RS physical layer frame structure, except for DLHeader, DL Header RX, RRS and DL Relay Subchannel, the BS transmitter and different RS receivers pass different subchannels The channel and OFDMA symbol combination share the rest of the BS downlink subframe or RSRX uplink subframe to communicate with SS/MS _BS and SS/MS _RS respectively, avoiding "SS/MS _RS to SS/MS _BS " interference.

In the uplink subframe of the BS physical layer frame structure or the downlink subframe of the RS physical layer frame structure, except for the corresponding period of DLHeader, Ranging Subchannel, RRS TX and UL Relay Subchannel, the BS receiver and different RS transmitters pass different The combination of subchannels and OFDMA symbols in the RS share the rest of the RS downlink subframe or the BS uplink subframe to communicate with the SS/MS _BS and SS/MS _RS respectively, avoiding the interference from "SS/MS _BS to SS/MS _RS ".

Define the "DL Header (downlink subframe header)" in the downlink subframe (DL _BS ) with the frequency of f1 in the physical layer frame structure of the BS, which is the beginning of the downlink subframe and is used to define the subchannel and subchannel for sending user synchronization information The OFDMA symbol combination and the subchannel and OFDMA symbol combination for sending indication information to indicate the location and usage method profile of each subchannel and OFDMA symbol combination in the downlink subframe and uplink subframe of the BS physical layer frame structure. Contains the preamble, FCH, DL-MAP, UL-MAP in the original 802.16OFDMA (or SOFDMA) frame, SS/MS _BS , RS and BS keep sending and receiving frames synchronously. Define "DL Header RX (downlink subframe header reception)" in the uplink subframe (UL _RS ) with the frequency f1 of the physical layer frame structure of the RS, which is used to define the subchannel and OFDMA symbol combination of the DL Header of the receiving BS. The time-frequency relationship between the DL Header of the BS and the DL Header RX of the RS must correspond to each other and be strictly synchronized.

Define "RangingSubchannel (ranging subchannel)" in the uplink subframe (UL _BS ) with the frequency f2 of the physical layer frame structure of the BS, and define the initial access ranging Ranging and periodic ranging for SS/MS _BS Ranging, BS ranging receiving subchannel and OFDMA symbol combination for bandwidth request.

The physical layer frame structure of the BS and RS in the advanced relay mode of the present invention _as shown in FIG. Subframe header)" is the beginning of the downlink subframe, which is used to define the combination of subchannels and OFDMA symbols for sending user synchronization information and the combination of subchannels and OFDMA symbols for sending indication information, so as to indicate the RS physical layer frame structure downlink subframe and The location and usage profile of each subchannel and OFDMA symbol combination in the uplink subframe. Including the preamble, FCH, DL-MAP, UL-MAP in the original 802.16OFDMA (or SOFDMA) frame, SS/MS _RS and RS keep sending and receiving frames synchronously.

During the DL Header period of the RS, the uplink subframe (UL _BS ) of the BS does not arrange any combination of receiving subchannels and OFDMA symbols to avoid interference from "SS/MS _BS to SS/MS _RS ".

During the DL Header period of the RS, the downlink subframe (DL _RS ) of the physical layer frame structure of other RSs cannot arrange any combination of sending subchannels and OFDMA symbols to avoid interference from "RS to SS/MS _RS "; or, if different RS If the DL Headers overlap in time, they must completely overlap and be strictly synchronized, and their contents must be the same to avoid interference from "RS to SS/MS _RS ".

Define "RelayRanging Subchannel (relay ranging subchannel, RRS for short)" in the uplink subframe (UL _RS ) with the frequency of f1 in the physical layer frame structure of RS, and define the initial access ranging Ranging for SS/MS _RS , periodic ranging Ranging, RS ranging receiving subchannel and OFDMA symbol combination for bandwidth request.

"NULL" in FIGS. 8 and 9 is a part that does not arrange any reception or transmission. Wherein, the "white area" in the BS downlink subframe (DL _BS ) and the RS downlink subframe (DL _RS ) is the DL Header; the "white area" in the RS uplink subframe (UL _RS ) is the DL Header RX.

The transfer communication process based on the above physical layer frame structure and the secondary school system includes:

The first stage (base station to transit):

S1. The base station sends the preamble preamble in the first symbol or time slot in the downlink subframe (DL _BS ) "DL Header" with frequency f1;

S2. The transfer station receives the preamble in the base station downlink subframe (DL _BS ) "DL Header" through the "DL Header RX" in the transfer station uplink subframe (UL _RS ) with frequency f1, and synchronizes with the BS;

S3. The base station sends FCH, DL-MAP, and UL-MAP after the downlink subframe (DL _BS ) "DL Header" preamble with frequency f1;

S4. The relay station receives the FCH, DL-MAP, and UL-MAP of the downlink subframe (DL _BS ) "DL Header" through the "DL Header RX" in the uplink subframe (UL _RS ) of the relay station with frequency f1, and obtains the base station downlink and the time slot, subchannel and/or OFDMA symbol position and usage method (profile) information of each uplink burst;

S5. The base station sends the downlink relay communication data A to the relay station in the "DL Relay Subchannel" of the downlink subframe (DL _BS ) with frequency f1; the base station buffers the data A;

S6. The relay station receives the downlink relay communication data A sent by the base station in S5 through the "DL RelaySubchannel" in the uplink subframe (UL _RS ) of the relay station with frequency f1.

The second stage (user station to transfer station):

S1. Transmit the preamble in the first symbol or time slot in the downlink subframe (DL _RS ) "DL Header" with frequency f2;

S2. The subscriber station receives the preamble in the downlink subframe (DL _RS ) "DL Header" of the relay station with frequency f2, and synchronizes with the relay station;

S3. The relay station sends FCH, DL-MAP, UL-MAP in the downlink subframe (DL _RS ) with frequency f2 after the "DL Header"preamble;

S4. The user station receives the FCH, DL-MAP, and UL-MAP of the downlink subframe (DL _RS ) "DL Header" of the relay station with frequency f2, and obtains the subchannels and OFDMA symbol positions and usage methods of the downlink and uplink bursts of the relay station ( profile) information:

S5. In the uplink subframe (UL _RS ) of the transfer station with frequency f1, the user station sends uplink communication data B to the transfer station on the OFDM Subchannel except DL Header RX, RRS and UL Relay Subchannel; the user station caches data B;

S6. The relay station receives the uplink communication data B sent by the user station in step S5 from the corresponding OFDM Subchannel with frequency f1:

Among them, the "DL Relay Subchannel" of the first stage S6 and the OFDM SubchannelI of the second stage step S6 can be selected in the same uplink subframe of the transfer station to reduce the transfer delay.

The third stage (network coding):

S1. The transfer station performs network coding on the data A of the base station and the data B of the user station to obtain the coded data C. For example, directly perform "exclusive OR" operation processing on a bit basis, then $C=A\⊕B$

The fourth stage (transfer to base station and user station):

S1. The relay station sends the preamble in the first symbol or time slot of the downlink subframe (DL _RS ) "DL Header" with frequency f2;

S2. The user station receives the preamble in the downlink subframe (DL _RS ) "DL Header" of the relay station with frequency f2, and synchronizes with the relay station;

S3. The relay station sends FCH, DL-MAP, and UL-MAP after the downlink subframe (DL _RS ) "DdL Headerr" preamble with frequency f2; the relay station specifically instructs the relay destination user station of the base station in the DL MAP to UL Relay Subchannel Receive data;

S4. The subscriber station receives the FCH, DL-MAP, and UL-MAP of the downlink subframe (DL _RS ) "DL Header" with frequency f2, and obtains the time slots, subchannels and/or OFDMA symbols of each downlink and uplink burst of the relay station location and usage (profile) information;

S5. The relay station sends the network encoded data C to the base station and the relay in the "UL RelaySubchannel" of the relay station downlink subframe (DL _RS ) with frequency f2;

S6. The destination user station receives the network coded data C sent by the relay station from the "UL Relay Subchannel" whose frequency is f2 in step S5 according to the instructions in the relay station's DL MAP, and the BS receives the network coded data C sent by the relay station from the "UL Relay Subchannel" whose frequency is f2 in step S5. Receiving the network coded data C sent by the relay station in "Relay Subchannel";

The fifth stage (network decoding):

S1. The destination user station performs network decoding on the cached data B and the received network coded data C, and obtains the data A transferred by the base station through the transfer station, for example, the data B cached by the destination user station and the network coded data Do "XOR" operation to get the data A of the base station, namely $B\⊕(A\⊕B)=A;$

S2. The base station performs network decoding on the cached data A and the received network coded data C, and obtains the data B transferred by the user station through the transfer station, for example, the data A cached by the base station and the network coded data Do the "exclusive OR" operation to get the transferred data B, that is $A\⊕(A\⊕B)=B.$

Wherein, step S1 and step S2 have no affiliation relationship.

In summary, the present invention defines the physical layer frame structure of BS and RS by introducing the mechanism of OFDMA (or OFDM sub-channel) technology and network coding technology, so that the throughput of the wireless relay communication system can be increased to the greatest extent, and can Effectively avoid all kinds of interference that may exist.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present invention can easily think of changes or Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (32)

1. A wireless relay communication system, characterized in that: Including the base station, transfer station and user terminal, the transfer station performs wireless communication with the base station and user terminal in frequency division duplex mode; The transfer station is respectively provided with interfaces for communicating with the base station and the user terminal, and the transfer station includes a frequency division duplex wireless transceiver and a wireless link layer processing unit based on network coding technology; Both the base station and the user terminal include a frequency division duplex wireless transceiver and a wireless link layer processing unit based on network decoding technology; The frequency division duplex wireless transceivers of the transfer station, the base station and the user terminal include a frequency division duplex wireless transmitter physical layer processing unit and a frequency division duplex wireless receiver physical layer processing unit; The frequency division duplex wireless transmitter physical layer processing unit of the transfer station corresponds to the frequency division duplex wireless receiver physical layer processing unit in the base station and the user terminal respectively; the frequency division duplex wireless receiver physical layer processing unit of the transfer station respectively Corresponding to the physical layer processing unit of the frequency division duplex transmitter in the base station and the user terminal; Wherein, the downlink broadcast burst of the downlink base station is directly sent by the base station to the user terminal without being relayed by a relay station, wherein the downlink broadcast burst of the downlink base station includes: a preamble, a frame control header, a downlink mapping table and an uplink mapping table ; The initial access ranging, periodic ranging, and bandwidth request of the user terminal are measured through the ranging sub-channel of the uplink base station, and are directly sent to the base station by the user terminal without relaying through the relay station; the downlink burst of the downlink base station is excluded Messages other than the preamble, frame control header, downlink mapping table, and uplink mapping table must be relayed through the relay station; the uplink burst of the uplink base station except the initial access ranging and periodicity of the user terminal Packets other than ranging and bandwidth requests must be relayed through the relay station. 2. The system according to claim 1, characterized in that: the frequency division duplex wireless transmitter physical layer processing unit of the base station and the frequency division duplex wireless receiver physical layer processing unit are respectively connected with the frequency division duplex wireless receiver of the user terminal. The physical layer processing unit of the receiver corresponds to the physical layer processing unit of the frequency division duplex wireless transmitter. 3. The system according to claim 1 or 2, wherein the transfer station includes: Frequency division duplex wireless transmitter physical layer processing unit: wirelessly communicates with the frequency division duplex wireless receiver physical layer processing unit in the base station and user terminal, and sends transit data to the base station and user terminal; Frequency division duplex wireless receiver physical layer processing unit: perform wireless communication with the wireless transmitter physical layer processing unit in the base station and user terminal, and receive the transfer data sent by the base station and user terminal; Wireless link layer processing unit: For the transfer data from the physical layer processing unit of the frequency division duplex wireless receiver, after data receiving processing, network coding and sending processing, forward it to the physical layer processing unit of the frequency division duplex wireless transmitter. 4. The system according to claim 1, wherein the base station includes: Frequency division duplex wireless transmitter physical layer processing unit: corresponding to the physical layer processing unit of the frequency division duplex wireless receiver of the transfer station and/or user terminal, receiving the transfer data sent by the transfer station; Frequency division duplex wireless receiver physical layer processing unit: corresponds to the frequency division duplex wireless transmitter physical layer processing unit of the transfer station, and sends transfer data to the transfer station; Wireless link layer processing unit: For the data from the physical layer processing unit of the frequency division duplex wireless receiver, perform data reception processing and network decoding, and then forward it to the transmission processing unit; perform data transmission processing on the data from the transmission processing unit After that, it is forwarded to the physical layer processing unit of the frequency division duplex transmitter. 5. The system according to claim 4, further comprising: Transmission processing unit: establish communication with upper-level equipment or with a group of base station equipment respectively, and perform information interaction. 6. The system according to claim 5, wherein the transmission processing unit is a wired transmission processing unit. 7. The system according to claim 1, wherein the user terminal comprises: Frequency division duplex wireless transmitter physical layer processing unit: communicate wirelessly with the frequency division duplex wireless receiver physical layer processing unit of the transfer station, and send uplink transfer data to the transfer station; Frequency division duplex wireless receiver physical layer processing unit: wirelessly communicates with the frequency division duplex wireless transmitter physical layer processing unit of the transfer station, and receives the transfer data sent by the transfer station; Wireless data link layer processing unit: For the data from the physical layer processing unit of the frequency division duplex wireless receiver, perform data reception processing and network decoding, and then forward it to the user; for the data from the user, perform data transmission processing, and forward it For the frequency division duplex wireless transmitter physical layer processing unit. 8. The system according to claim 2, wherein the user terminal comprises: The first and second frequency division duplex wireless transceivers: the first and second frequency division duplex wireless receiver physical layer processing units, the first and second frequency division duplex wireless transmitter physical layer processing units and wireless data The link layer processing unit is composed; among them: The first frequency division duplex wireless receiver physical layer processing unit: corresponds to the frequency division duplex wireless transmitter physical layer processing unit of the base station, and receives part of the data sent by the base station; The second frequency division duplex wireless receiver processing physical layer unit: corresponds to the frequency division duplex wireless transmission physical layer processing unit of the transfer station, and receives the transfer data sent by the transfer station; The first frequency division duplex wireless transmitter physical layer processing unit: corresponds to the frequency division duplex wireless receiver physical layer processing unit of the base station, and sends part of the data to the base station; The second frequency division duplex wireless transmitter physical layer processing unit: corresponds to the frequency division duplex wireless receiver physical layer processing unit of the transfer station, and sends transfer data to the transfer station; Wireless data link layer processing unit: after receiving, processing and network decoding the data from the first and/or second frequency division duplex wireless receiver physical layer processing unit, forwarding to the user, after sending and processing the data from the user , forwarded to the physical layer processing unit of the first and/or second frequency division duplex wireless transmitter. 9. The system according to claim 2, characterized in that: the transfer station receives the communication data at the first frequency, and sends the communication data at the second frequency; the base station and the user terminal receive the communication data at the transfer station at the second frequency, and send the communication data at the second frequency. A frequency sends communication data to the relay station. 10. The system according to claim 9, characterized in that: the base station also provides an interface for communicating with the user terminal, when the base station communicates directly with the user terminal under the coverage of the relay station, the user terminal communicates with the base station at the second frequency The communication data is sent, and the communication data of the base station is received at the first frequency. 11. The system according to any one of claims 1, 2, 4 or 9, characterized in that the frequency division duplex wireless transceiver adopts an OFDM access mode for communication. 12. A wireless relay communication method, characterized in that it comprises the steps of: A. Set the downlink middle rotor channel and the uplink middle rotor channel in the downlink subframe and uplink subframe of the physical layer frame structure of the base station respectively, which are used to define the downlink middle rotor channel and orthogonal frequency division of the base station transmitted by the base station to the transfer station The combination of multiplexed access symbols, and the uplink intermediate rotor channel of the base station and the orthogonal frequency division multiplexing access symbol combination transmitted by the relay station to the base station; the downlink intermediate rotor channel is set in the uplink subframe of the physical layer frame structure of the relay station, It is used to define the intermediate rotor channel and OFDM access symbol combination of the downlink intermediate rotor channel of the relay station receiving the base station, and the uplink intermediate rotor channel is set in the downlink subframe of the physical layer frame structure of the relay station, which is used to define the relay The station receives the uplink mid-rotor channel and the OFDM access symbol combination of the base station; B. Between the base station, the transfer station and the user terminal, based on the uplink and downlink physical layer frames of the base station and the transfer station, the frequency division duplexing method is used to perform orthogonal frequency division multiplexing access to wireless transfer communication; When the base station communicates directly with the user terminal under the coverage of the relay station, the base station converts the preamble, frame control header, downlink mapping table and uplink mapping table into The information is directly sent to the user terminal from the interface communicating with the user terminal. For the initial ranging contention time slot and bandwidth request contention time slot of the uplink subframe of the base station, or ranging sub-channel ranging, the user terminal adopts a method different from other transmitted data. The channel coding and modulation mode or different transmit powers are directly sent from the user terminal to the base station without being relayed by a relay station. 13. The method according to claim 12, wherein said step A further comprises: setting a transit ranging subchannel in the uplink subframe of the physical layer frame structure of the base station, for defining an initial access channel for the transit station Incoming ranging, periodic ranging, bandwidth request base station relay ranging receiving subchannel and OFDM access symbol combination; In the downlink sub-frame of the physical layer frame structure of the transfer station, the relay ranging sending sub-channel is set, which is used to define the transfer station’s initial access ranging, periodic ranging, and bandwidth request. cross frequency division multiplexing access symbol combination; The time-frequency relationship of the relay ranging sub-channels set in the base station and the relay station is in one-to-one correspondence and synchronization. 14. The method according to claim 13, characterized in that: the uplink transit ranging subchannel of the uplink subframe of the base station can also be used as the initial access ranging, periodic ranging, and bandwidth request ranging subchannel of the user terminal use. 15. The method according to claim 12, wherein said step A further comprises: setting a downlink subframe header in the downlink subframe of the base station physical layer frame structure, the downlink subframe header being the beginning of the downlink subframe , which is used to define the combination of subchannels and OFDM access symbols for sending user synchronization information and the combination of subchannels and OFDM access symbols for sending indication information, so as to indicate the downlink sub-channels of the physical layer frame structure of the base station The location and usage method of each subchannel and OFDM access symbol combination in the frame and uplink subframe; Setting downlink subframe header reception in the uplink subframe of the physical layer frame structure of the transfer station is used to define the downlink subframe header subchannel and OFDM access symbol combination of the physical layer frame structure of the receiving base station; The downlink subframe header of the physical layer frame structure of the base station and the time-frequency relationship received by the downlink subframe header of the physical layer frame structure of the transfer station are one-to-one corresponding and synchronized. 16. The method according to claim 15, wherein the downlink subframe header of the physical layer frame structure of the base station includes: a preamble, a frame control header, a downlink mapping table and an uplink mapping table, so that users belonging to the base station The terminal, the transfer station and the base station keep sending and receiving frames synchronously; The downlink subframe header of the physical layer frame structure of the transfer station includes a preamble, a frame control header, a downlink mapping table and an uplink mapping table, so that the user terminal belonging to the transfer station and the transfer station maintain frame synchronization in sending and receiving. 17. The method according to claim 12, wherein said step A further comprises: Set the ranging subchannel in the uplink subframe of the physical layer frame structure of the base station, which is used to define the user terminal's initial access ranging, periodic ranging, bandwidth request base station ranging receiving subchannel and OFDM access symbol combination; The relay ranging sub-channel is set in the uplink subframe of the physical layer frame structure of the transfer station, which is used to define the initial access ranging, periodic ranging, and bandwidth request of the user terminal. Division multiplexing access symbol combination. 18. The method according to claim 12, wherein said step A further comprises: Set the downlink subframe header in the downlink subframe of the physical layer frame structure of the transfer station. The downlink subframe header is the beginning of the downlink subframe and is used to define the subchannel and OFDM access symbol for sending user synchronization information Combining and sending indication information of subchannels and OFDM access symbol combinations to indicate the position and use of each subchannel and OFDM access symbol combination of the downlink subframe and uplink subframe of the relay station method. 19. The method according to claim 12, wherein said step A further comprises: When there are at least two relay stations, different downlink mid-rotor channels and uplink mid-rotor channels are respectively set in the physical layer frame structure of the base station for the at least two transfer stations; the frequency division duplex wireless transmitters of different transfer stations only Send the relay data of the base station in the corresponding uplink intermediate rotor channel, and do not arrange to send the relay data of the base station in other sub-channels; the frequency division duplex wireless receivers of different relay stations only receive the base station in the corresponding downlink intermediate rotor channel The transfer data of the base station is not arranged to receive the transfer data of the base station in other sub-channels. 20. The method according to any one of claims 12-19, characterized in that Step B specifically includes: in the uplink and downlink physical layer frames of the base station and the relay station based on the settings between the base station, the relay station and the user terminal The included uplink and downlink intermediate rotor channels, relay ranging sub-channels, downlink sub-frame headers, downlink sub-frame header receiving, and ranging sub-channels perform message interaction to realize wireless relay communication. 21. The method according to claim 20, wherein said step B further comprises: During the uplink middle rotor channel of the base station, the user terminal belonging to the base station does not arrange any combination of transmission subchannels and OFDM access symbols, and during the downlink middle rotor channel of the base station, the user terminal belonging to the relay station does not arrange any A combination of subchannels and OFDM access symbols is sent. 22. The method according to claim 20, wherein said step B further comprises: In the downlink subframe of the physical layer frame structure of the base station or the uplink subframe of the physical layer frame structure of the transfer station, except for the period corresponding to the downlink subframe header, downlink subframe header reception, transfer ranging subchannel and downlink intermediate rotor channel, the base station transmits Through different combinations of subchannels and OFDM access symbols, the machine and different transfer station receivers share the rest of the downlink subframe of the base station or the uplink subframe of the transfer station receiving module, so as to communicate with the user terminals belonging to the base station respectively. Communicating with user terminals belonging to transfer stations; In the uplink subframe of the physical layer frame structure of the base station or the downlink subframe of the physical layer frame structure of the transfer station, except for the corresponding periods of the downlink subframe header, ranging subchannel, relay ranging sending subchannel and uplink intermediate rotor channel, The base station receiver and different relay station transmitters share the rest of the relay station downlink subframe or the base station uplink subframe through different subchannels and OFDM access symbol combinations, so as to communicate with the user terminals belonging to the base station respectively Communicate with user terminals belonging to the transfer station. 23. The method according to claim 20, wherein the step B comprises: during the head of the downlink subframe of the transfer station, the uplink subframe of the base station does not arrange any receiving subchannel and OFDM access Enter the combination of symbols. 24. The method according to claim 20, characterized in that the step B comprises: during the head of the downlink subframe of the relay station, the downlink subframes of other relay stations do not arrange any transmission subchannels and OFDM Combined with access symbols; or, if the downlink subframe headers of different relay stations overlap in time, the downlink subframe headers of different relay stations must be completely overlapped and synchronized in time, and their contents must be the same. 25. The method according to claim 12, wherein the frequency of the downlink subframe of the base station physical layer frame structure and the uplink subframe of the transfer station physical layer frame structure is the first frequency, and the frequency of the uplink subframe of the base station physical layer frame structure The frequency of the frame and the downlink subframe of the physical layer frame structure of the transfer station is the second frequency. 26. A wireless relay communication method, comprising the following steps: A. The base station sends downlink transfer data to the transfer station in frequency division duplex mode in the downlink middle rotor channel of the downlink subframe of the base station and buffers the data; the user terminal receives and transfers the data in the transfer station's uplink subframe except the downlink subframe Send the uplink transit data to the transfer station in the frequency division duplex mode in the ranging subchannel and the OFDM subchannel outside the uplink middle rotor channel, and buffer the data; B. The transfer station performs network coding processing on the received downlink transfer data of the base station and the uplink transfer data of the user terminal, and then simultaneously sends them to the base station and the user terminal in a frequency division duplex manner; C. The base station and the user terminal perform network decoding processing on the buffered data and the network-encoded transfer data sent by the transfer station, and respectively obtain the uplink transfer data of the user terminal and the downlink transfer data of the base station; Wherein, the downlink broadcast burst of the downlink base station is directly sent by the base station to the user terminal without being relayed by a relay station, wherein the downlink broadcast burst of the downlink base station includes: a preamble, a frame control header, a downlink mapping table and an uplink mapping table ; The initial access ranging, periodic ranging, and bandwidth request of the user terminal are measured through the ranging sub-channel of the uplink base station, and are directly sent to the base station by the user terminal without relaying through the relay station; the downlink burst of the downlink base station is excluded Messages other than the preamble, frame control header, downlink mapping table, and uplink mapping table must be relayed through the relay station; the uplink burst of the uplink base station except the initial access ranging and periodicity of the user terminal Messages other than ranging and bandwidth requests must be transferred through the transfer station. 27. The method according to claim 26, wherein said step A comprises: A1. The base station sends the preamble in the downlink subframe header of the downlink subframe, and the relay station receives the preamble through the downlink subframe header receiving subchannel in the uplink subframe of the relay station, and synchronizes with the base station; A2. After the base station sends the preamble in the downlink subframe, it sends the frame control header, downlink mapping table and uplink mapping table information, and the transfer station receives the subchannel through the downlink subframe header receiving subchannel in the uplink subframe of the transfer station. Frame control header, downlink mapping table, and uplink mapping table information, to obtain the time slot, subchannel, and/or OFDM access symbol combination position and usage method information of each downlink and uplink burst of the base station; A3. The base station sends downlink relay data to the relay station in the downlink intermediate rotor channel of the downlink subframe, and buffers the data. The relay station receives the downlink relay data of the base station through the downlink intermediate rotor channel in the uplink subframe of the relay station. 28. The method according to claim 27, wherein said step A further comprises: A4. The relay station sends a preamble in the downlink subframe header of the relay station's downlink subframe, and the user terminal receives the preamble and synchronizes with the relay station; A5. The transfer station sends the frame control header, downlink mapping table, and uplink mapping table information in the downlink subframe of the downlink subframe of the transfer station, and the user terminal receives the frame control header, downlink mapping table, and uplink mapping table information, and obtains the transfer station Sub-channel and OFDM access symbol combination position and usage information of each downlink and uplink burst; A6. The user terminal sends uplink transfer data to the transfer station in the OFDM sub-channels of the transfer station's uplink subframe except for the downlink subframe head reception, transfer ranging sub-channel and uplink middle rotor channel, and buffers the data. The uplink transfer data of the user terminal is received in the corresponding OFDM sub-channel. 29. The method according to claim 28, wherein said step A further comprises: The corresponding OFDM sub-channel described in A6 may be selected in the same uplink sub-frame of the relay station as the downlink middle rotor channel in the uplink sub-frame described in A3. 30. The method of claim 26, wherein step B comprises: B1. The transfer station performs network coding processing on the received downlink transfer data of the base station and the uplink transfer data of the user terminal to obtain the encoded transfer data; B2. The transfer station sends a preamble in the downlink subframe header of the transfer station's downlink subframe, and the user terminal receives the preamble and synchronizes with the transfer station; B3. The transfer station sends the frame control header, downlink mapping table, and uplink mapping table information in the downlink subframe header of the downlink subframe of the transfer station, and the user terminal receives the frame control header, downlink mapping table, and uplink mapping table information, and obtains the relay Information about the combination position and usage method of time slots, sub-channels and/or OFDM access symbols for downlink and uplink bursts of the station; B4. The relay station sends the encoded relay data to the base station and the user terminal in the uplink middle rotor channel of the downlink subframe of the relay station, and the base station and the user terminal receive the coded relay data from the uplink middle rotor channel. 31. The method according to claim 30, wherein said step B1 specifically comprises: The transfer station directly performs an exclusive OR operation on a bit basis between the data sent by the base station and the data sent by the user terminal to obtain coded data. 32. The method according to claim 31, wherein said step C comprises: The user terminal performs XOR operation on the buffered data and the received encoded transfer data sent by the transfer station to obtain the downlink data of the base station; the base station combines the buffered data with the received encoded transfer data sent by the transfer station After the transfer data is processed by XOR operation, the uplink transfer data of the user terminal is obtained.