A method and device in RSs of jointly processing and
a method and device in BSs of corresponding processing

Technological field
The invention relates to wireless relay network  especially to a method and device  in RSs  of jointly processing wireless signals from multi mobile terminals  and to a method and device  in BSs  for correspondingly processing assisted by RSs.

Background of the arts
The wireless relay technology is significantly meaningful for improving network capacity and enhancing network coverage. Therefore  the wireless relay is an important component of World Interoperability for Microwave Access (WiMAX) network based on IEEE802.16 protocol. Meanwhile  many companies propose applying wireless relay technology in long-term revolution wireless network(LTE) and further revolution network of long-term revolution(LTE-Advanced).
Present RSs (Relay Stations) are mainly divided into layer 1 (L1) RS and layer 2 RS. Wherein  L1 RS forwards straight the uplink signals from mobile terminals after receiving them  without decoding. Differently  L2 RS decodes  filters and recodes the uplink signals from mobile terminals  then forwards it to BSs.
The two kinds of RSs have their own advantages and disadvantages by comparison:
L1 RSs needn’t equip with codec for not decoding uplink signals. And there is little delay generated in L1 RS. However  there is more noise carried in the forwarded signals  compared to L2 RS.
L2 RSs need equip with codec  for that they need to decode uplink signals. Therefore  there is more cost and more delay generated by encoding and decoding  compared to L1 RS. The advantage of L2 RS is filtering noise in the forwarded signals  which benefits the reception of the signals in BSs.
Suppose a wireless relay network with frequency division multiplex among multi users (see Fig.1)  e.g. LTE-TDD. Wherein  uplink and downlink communications among mobile terminals and BSs adopt time-divided mode.
Wherein  each mobile terminal 30-35 in the margin of the cell broadcasts its own uplink signal in a different frequency. Those uplink signals not only arrive at the base station (BS or e-Node B) 10  but also at the RS 20.
Then the BS 10 buffers the uplink signals received straight from each mobile terminal. The RS 20 demodulates and decodes each uplink signal  filters noise  encodes and modulates the signal  then transmits it to the BS 10 at orthogonal frequency. Finally  the BS 10 merges the uplink signals received straight from each mobile terminal and forwarded by the RS 20  which leads to getting extra 1-order diversity gain from the RS 20.
But  in this scheme  the RS 20 usually receives the uplink signals from each mobile terminal simultaneously while processes them separately. The 1-order diversity gain above is very limited and not optimal in low SNR case.
IEEE Journal on Selected Areas in Communications  vol.26  no.3  Apr. 2008 records wrote by T.Wang and G.B. Giannakis. Wherein  it proposes merging the uplink signals from multi mobile terminals in symbol of modulation level  in order to get extra joint-process gain. But the scheme has the poor performance in low SNR case.

Summary of invention
The invention is proposed to solve the above problems in the prior art. According to an embodiment of the invention  a RS demodulates and decodes M uplink signals from M mobile terminals  and uses each of one or more shift parameter groups to implement the following operations: Based on M shift parameters in the group  shifting M decoded bit streams respectively and merging the M shifted bit streams  then obtaining a check bit stream. Hence  N check bit streams are obtained by using the one or more (denoted as N herein) shift parameter groups. Then  the RS transmits the N check bit streams to the BS. The BS has received the M uplink signals from the mobile terminals in advance. Then  the BS can enhance the detection of the uplink signals  by taking the N check bit steams as check information of those uplink signals  in order to reduce error rate. According to at least one embodiment of the invention  the error rate is embodied by user error rate (UER) and block error rate (BLER). Wherein  without loss of generality  the M check bit streams are inter-user parity-check codes  e.g. low density parity check code (LDPC).
According to an embodiment of the invention  N is equal or less than M and equal or more than 1.
According to one aspect of the invention  it is provided a method  used for joint processing  in the RS of wireless relay network  wherein  the method comprises the following steps: Demodulating and decoding respectively multiple paths of uplink signals from multiple mobile terminals  in order to generate multiple decoded bit streams;Based on each one of one or more shift parameter groups  implementing respectively the following operations  wherein  each shift parameter group comprises M shift parameters:Based on M shift parameters in the shift parameter group  shifting M decoded bit streams in the multiple decoded bit streams respectively  in order to generate M shifted bit streams; Merging the M shifted bit streams  in order to generate a check bit stream;Sending to the BS the one or more check bit streams  the check bit streams will be used to process multi-user detection in the BS.
According to another aspect of the invention  it is provided a method  in a BS of wireless relay network, used for processing uplink signals from multiple mobile terminals  wherein  the method comprises the following steps:- obtaining one or more shift parameter groups;
Wherein  the one or multi shift parameter groups are used in the RS to shift process M decoded bit streams in decoded multiple bit streams which are demodulated and decoded from uplink signals of the multi mobile terminals; Still comprises:- Receiving one or more check bit streams transmitted from the RS;- Based on the one or more check bit streams and the one or more shift parameter groups  processing the M paths of uplink signals from the M mobile terminals.
According to yet another aspect of the invention  it is provided a first device of jointly processing in RSs in wireless relay network. Wherein  it comprises demodulator and decoder  for demodulating and decoding respectively multiple paths of uplink signals from multiple mobile terminals in order to generate multiple decoded bit streams; shifting unit and merging unit which based on each one of one or more shift parameter groups implements respectively the following operations  wherein  each shift parameter group comprises M shift parameters:Based on M shift parameters in the shift parameter group  shifting M decoded bit streams in the multiple decoded bit streams respectively  in order to generate M shifted bit streams; Merging the M shifted bit streams in order to generate a check bit stream; transmitter  for sending to the BS the one or more check bit streams  the check bit streams will be used to for multi-user detection in the BS.
According to still another aspect of the invention  it is provided a second device  in BSs in wireless relay network  of processing uplink signals from multiple mobile terminals. Wherein  it comprises obtaining unit for obtaining one or more shift parameter groups; Wherein  the one or multi shift parameter groups are used in the RS to shift process M decoded bit streams in decoded multiple bit streams which are demodulated and decoded from uplink signals of the multi mobile terminals; second receiver  for receiving one or more check bit streams transmitted from the RS; executing unit  for based on the one or more check bit streams and the one or more shift parameter groups  processesing the M paths of uplink signals from the M mobile terminals.
By adopting the method and device proposed by the invention  it’s ensured that relatively ideal error user rate and error block rate for multi-user detection in BSs can be guaranteed in the low SNR case. Besides  it’s ensured to reduce network propagation delay on the presumption of acceptable error rate  by flexibly using a few shift parameter groups  i.e. transmitting other information (signals) by using the wireless resources for transmitting check bit streams.

Brief description of the drawings
By reading the detailed description of non-limiting embodiment in conjunction with the drawings  the other features and advantages of the invention will become clearer. Wherein  the same or similar reference signs mean the same or similar features of steps or devices (modules).
Fig.1 is a typical schematic diagram of wireless relay network;
Fig.2 is a flow diagram of the system method of the joint processing in RSs and the corresponding processing in BSs;
Fig.3 is a schematic diagram of M bit streams comprising Turbo code redundancy and M bit streams which the relay device forwards;
Fig.4 shows shift parameters according to an embodiment of the invention;
Fig.5 is a schematic diagram of the shift mode according to an embodiment of the invention;
Fig.6 is a comparative diagram of simulation results of error user rate between the embodiment of the invention and the prior art;
Fig.7 is a comparative diagram of simulation results of error block rate between the embodiment of the invention and the prior art;
Fig.8 is a block diagram of the first device for jointly processing in RSs  according to an embodiment of the invention;
Fig.9 is a block diagram of the second device for processing uplink signals from multiple mobile terminals in BSs  according to an embodiment of the invention.

Detailed description of the embodiment
Fig.2 is a flow diagram of system method used for multi-user detection in wireless communication network according to a detailed embodiment of the invention. The following is the detailed description of the method proposed by the invention referring to Fig.2 with Fig.1.
The method begins with S30. Wherein  each of mobile terminals 31-35 transmits one uplink signal respectively in orthogonal frequency. Since the 5 uplink signals are all broadcasted  the RS 20 and BS 10 can receive them. Wherein  it’s required that there is a direct or indirect channel between the BS 10 and each mobile terminal  i. e. the BS 10 can receive uplink signals transmitted straight from each mobile terminal or forwarded from another RS which is not shown in Fig. 1.Wherein  the other RS preferably uses different wireless resources from those used by the RS 20 to communicate with the BS 10  e.g. in frequency division or time division multiplex.
There is enough introduction of realization of S30 in the art. The article will not discuss in detail.
In the example  the RS 20 jointly processes 5 uplink signals from mobile terminals 31-35  i.e. M is equal to 5. Those skilled in the field can understand the mobile terminals served by the RS 20 may be more than 5(mobile terminals 31-35)  e.g. 8 in total. But not all those mobile terminals are suitable to be applied with the method of joint processing  provided for RSs by the invention. Then the RS 20 flexibly selects some   e.g. mobile terminals 31-35 that meet preset conditions  to carry out the procedure introduced in detail in the following. They meet the following conditions.
First condition: The frame sizes of the mobile terminals 31-35 meet preset conditions. In detail  the frame sizes are substantially the same. For the one or some with shorter frame size  they may be zero filled at the end of frame and then join the follow-up operation.
Second condition: The mobile terminals 31-35 adopt the same modulation mode  e.g. BPSK or QPSK.
Optimally  the multiple mobile terminals jointly processed by the RS 20 usually are far from the BS 10  such that the quality of uplink signals at the BS 10 is poor  e.g. low SNR and it especially needs extra information provided by the RS 20.
It should be understand that the above selection is not necessary. E.g. the 8 mobile terminals temporarily located in the cell administered by the BS 10 are always made the objects that need to be jointly processed by the RS 20  until one moves out the cell or moves to a location quite near the BS 10.
According to the example  when the RS 20 selects the above mobile terminals  the selection procedure preferably repeats periodically  which may be independent of the method and procedure showed in Fig. 2.
For the 3 paths of uplink signals transmitted from the 3 of 8 mobile terminals except for 31-35  the RS 20 may process them according to the conventional relay mode in L2 RSs  i.e. to demodulate  decode and filter the signals from noise  then to transmit them to the BS at orthogonal frequency after coding and modulating independently. Accordingly  the method that the BS 10 adopts to process the uplink signals from 3 mobile terminals is the same with the prior art. This article will not give unnecessary description. And the followings mainly make an introduction for the mobile terminals 31-35.
Back to the flow diagram in Fig. 2  in S10  the BS buffers the 5 paths of uplink signals from mobile terminals 31-35 after receiving them  and waits for the check information transmitted from the RS 20 in next moment.
Equally  the RS 20 demodulates and decodes the 5 paths of uplink signals in S20  to obtain 5 decoded bit streams (see upper half of fig. 3). Wherein  for more generality  the number of mobile terminals  jointly processed in the RS 20 for multi-user detection in the BS 10  is set to M. Those skilled in the field can understand that the value should be set to 5 in the present embodiment. USER1-USERM correspond respectively to one of M paths of uplink signals transmitted from each mobile terminals  i.e. the decoded bit streams after demodulating and decoding. Wherein  taking User 1 as example  from U1,1 to U1,k mean the k decoded original bits  aimed at which the mobile terminal 1 implements channel encoding. While from U1,k+1?U1,l mean the check information of Turbo code.
The RS transmits M bit streams to the BS after encoding and modulating them (see lower half of Fig. 3). Wherein  taking RLY 1 as example  in the art there is no difference in the first k bits between RLY 1 and USER 1. I.e. RLY 1=USER 1 and so on. This is because the RS 20 just decodes and forwards (DF) data to get the first order diversity gain. While in at least one of embodiments of the invention  the contents of RLY 1-RLY M are different from that  and it is realized by S21 and S22 (see Fig. 2). Wherein  for convenience of description of bit steams transmitted by RSs in present technology   in the Fig. 3 M bit streams of RLY1 –RLYM are listed  since for the M uplink signals transmitted from M mobile terminals which need joint processing  the number of signals the RS DFs is M  corresponding to RLY 1-RLY M. While in the invention the number N of check bit streams (denoted by RLY with one sign) obtained by using one or more shift parameter groups is not always equal to M  but equal and less than M.
According to an embodiment of the invention  Galois Field i.e. network coding scheme is applied. Wherein  in S21 one or more  e.g. 5 shift parameter groups are used for the 5 mobile terminals in the RS 20. Wherein  each shift parameter group comprises 5 (i.e. M described above) shift parameters. And specifically  the following operations are carried out for each shift parameter group: each of decoded bit streams USER1-USER5 is shifted based on the 5 shift parameters  in order to generate 5 shifted bit streams.
Without loss of generality  one shift parameter above is showed in Fig.4. Wherein  n is the index of the shift parameter groups  and m indicates this shift parameter in the parameter group is corresponding to which mobile terminals (or decoded bit streams). In the example  as described above  the value ranges of n and m are positive integers of 1-5  i.e. N=M=5.
In the universal shift matrix (i.e. shift parameters) of shift parameters  there are M columns and M rows (see fig. 4). Wherein  “1”s of each row are all in the n*mth column and “1” of the second row is in (n*m+1)th column and so on. Wherein  the shift parameter may be realized by a shift
register.
The step S21 is also showed as the following:
(1)
Wherein  N is the number of shift parameter groups. means left cycle shifting bits of the mth decoded bit streams   by using the mth shift parameter in the nth shift parameter group. is the shifted bit stream obtained from shifting the .
Obviously  preferably  each shift parameter group should be different with each other  when using multiple shift parameter groups. It is actually ensured that different shifted bit streams are obtained after shifting the same decoded bit streams by using each shift parameter group. If multiple shift parameter groups are the same  the same M (i.e. 5) check bit streams are obtained after merging in the following S22  which has the same meaning as only one check bit stream for the BS 10.
According to Fig. 4 and formula (1)  a shift mode is obtained as showed in Fig. 5. Wherein  the row is corresponding to a shift parameter group and to a check bit stream generated finally. The column is corresponding to a shift parameter of the shift parameter group  and to a specific mobile terminal and a decoded bit stream. Each element in the table is the number of bits by which the bit stream is left cycle shifted under the action of a certain shift parameter of a certain shift parameter group.
Though the article makes an introduction of an example of shift parameter groups and shift parameters according to Fig. 4 and formula (1)  those skilled in the field can implement the shift operation in S21 to obtain N different or substantially different check bit streams  by using shift parameter groups and shift parameters in other forms without any creative work according to the teaching of the article. Wherein  the check bit streams substantially different mean the decoded bit streams  merged in S22 after shifted by two different shift parameter groups  generate two check bit streams which are the same in form by chance.
Preferably  it should be ensured by shift parameters that there is no girth 4 circle in Tyner diagram which is corresponding to network coded parity-check matrix. Otherwise it will reduce decoder performance  according to the decode theory.
According to the invention  the check information of Turbo code showed in Fig.3 may be involved or not in the shift operation described in the following. Without loss of generality  the introduction will not involve the check information of Turbo code in the shift operation.
According to the invention  advantageously  the RS 20 just needs to know how many mobile terminals will be in S21  i.e. data (signals or information) of how many mobile terminals the RS20 will jointly process to provide check bit streams to the BS 10. Then each shift parameter group will be obtained simply. This is because the number of mobile terminals is the M mentioned in context again and again.
In order to make the BS 10 analyze correctly the check bit streams provided by the RS 20  the invention proposes many modes of realization.
1. The functionality of determining shift parameters  same with that of the RS 20  is provided to the BS 10. I.e. the BS 10 just needs to know how many mobile terminals the RS 20 jointly processes with step S20-S21  then obtains the shift parameters which are similar but not limited as showed in Fig. 4.
2. The RS 20 reports in dedicated control channels to the BS 10 the shift parameters  e.g. it transmits the matrix showed in Fig. 4. Wherein  the BS 10 receives the notice for parameter groups from the RS 20  and extracts each parameter group needed. Surely  since the method needs to transmit matrixes  the overheads of signaling are more.
Those skilled in the field may select one from the two methods above  according to their needs during actual realization of the invention.
Alternatively  the RS 20 may merge each shifted bit streams to one check bit stream in S22  after obtaining 5 shifted bit streams by using 5 groups of shift parameters in S21. The RS 20 may also merge 5 decoded bit streams in S22 after they are shifted by using one group of shift parameters in S21  then use another group of shift parameters to repeat above operations until obtaining 5 check bit streams. Surely in any time the description of this article should not be understood as that the operation mode of S21 and S22 is limited by the invention.
The following is an introduction of S22. According to a detailed embodiment of the invention  the RS 20 implements exclusive or to the 5 shifted bit streams obtained from each group of shift parameters to generate a check bit stream. The procedure is well shown in formula (2).
RLY n=pn 1USER 1 pn 2USER 2 pn mUSER m (n=1 …  N) (2)
Wherein  RLY n is the check bit stream obtained by implementing exclusive or to M shifted bit streams by using the nth shift parameter group. And each of pn 1USER 1  pn 2USER 2 … pn mUSER m is shown in formula(1).
It can be seen that  in every bit stream obtained finally in S22  each bit represents a result of parity check. Wherein  multiple bit streams participate in exclusive or are obtained from cycle shift. Consequently if the BS 10 knows the shift mode used by the RS 20  it will know each check bit of each check bit stream is the obtained check result of which bit of the original decoded bit streams.
The RS 20 transmits 5 check bit streams generated to the BS 10 in the following S23, for assisting multi-user detection in BS 10.
In the example  N=M=5  i.e. 5 groups of shifted bit streams are obtained by using 5 shift parameter groups  and each group is merged into one check bit stream and finally 5 check bit streams are obtained. Then it""s better ensured less error probability when the BS 10 processes the 5 paths of uplink signals. Optionally  N may be less than M  i.e. the RS 20 may implement above operations by using 1 to 4 shift parameter groups. Then 1 to 4 check bit streams are provided to the BS 10. Compared to N=M case  this reducing check bit streams sacrifices some error rate (i.e. the error rate is higher). But some wireless resources are saved and may be allocated by BSs or RSs  so as to increase system transmission rate and reduce network delay.
Since the generation mode of check bit streams in the RS in the example is an encode mode of low density parity check(LDPC)  after receiving the 5 check bit streams from the RS 20  the BS 10 LDPC decodes the 5 uplink signals buffered in S10 based on the 5 check bit streams. The final output LLR (log-likelihood ratio) value can be used as either decision value or the input of Turbo decoder. Wherein  in the example it is not considered as the input of Turbo decoder.
Surely  when N is less than 5  the BS 10 can only receive less than 5 check bit streams. But this doesn’t essentially affect the decoding above in the BS  at most leads to higher error probability compared to the situation of 5 check bit streams.
Fig. 6 is the comparing diagram of simulation results of error user rate between the embodiment of the invention and the prior art.
Fig. 7 is the comparing diagram of simulation results of error block rate between the embodiment of the invention and the prior art. Wherein  a block is comprised of multiple frames from multi mobile terminals. The simulation environment is as the following:
- There are one BS  one RS and 3 mobile terminals in the network (all participate in the procedure showed in Fig.2).
- The result of LLR output is made the decision value directly  without inputting the result into Turbo encoder.
- All channels distribute independently by Rayleigh fading without consideration of loss of transmission path.
- Three mobile terminals all apply BPSK modulation
- The uplink frames of three mobile terminals are all 100 modulation symbols
Wherein  the upper curve in each diagram is variation curve of error user (block) rate vs. SNR based on the invention. The lower curve in each diagram is variation curve of error user (block) rate vs. SNR based on the present mode. Obviously there is clear superiority in the invention.
The following introduce each devices provided by the invention  by referring to device block diagram in conjunction with other drawings. Wherein  Fig.8 is a block diagram of the first device for jointly processing in RSs  according to an embodiment of the invention. And Fig.9 is a block diagram of the second device for processing uplink signals from multiple mobile terminals in BSs  according to an embodiment of the invention.
Wherein  the shown first device 200 comprises the first receiver 2001  demodulator and decoder 2002  shifting unit 2003  merging unit 2004  transmitter 2005 and selector 2006. The shown second device comprises obtaining unit 1001  the second receiver 1002 and execution unit 1003. In detail  the obtaining unit 1001 comprises the third receiver 10011 and extractor 10012.
Each of mobile terminals 31-35 respectively transmits one uplink signal in orthogonal frequency. Since the 5 uplink signals are all broadcasted  the RS 20 and BS 10 can receive them. Wherein  it’s required that there is a direct or indirect channel between the BS 10 and each mobile terminal  i. e. the BS 10 can receive uplink signals transmitted straight from each mobile terminal or forwarded from another RS which is not shown in Fig. 1. Wherein  the other RS preferably uses different wireless resources from those used by the RS 20 to communicate with the BS 10  e.g. in frequency division or time division multiplex.
There is enough introduction of realization of transmitting procedure of above uplink signals. The article will not discuss in detail. Those uplink signals will be received respectively by the first receiver 2001 in RS 20 and the second receiver 1002 in BS 21.
In the example  the first device in the RS 20 jointly processes 5 uplink signals from mobile terminals 31-35  i.e. M is equal to 5. Those skilled in the field can understand the mobile terminals served by the RS 20 may be more than 5(mobile terminals 31-35)  e.g. 8 in total. But not all those mobile terminals are suitable to be applied with the method of joint processing  provided for RSs by the invention. Then the RS 20 flexibly selects some  e.g. mobile terminals 31-35 that meet preset conditions  to carry out the procedure introduced in detail in the following. They meet the following conditions.
First condition: The frame sizes of the mobile terminals 31-35 meet preset conditions. In detail  the frame sizes are substantially the same. For the one or some with shorter frame size  they may be zero filled at the end of frame and then join the follow-up operation.
Second condition: The mobile terminals 31-35 adopt the same modulation mode  e.g. BPSK or QPSK.
Optimally  the multiple mobile terminals jointly processed by the RS 20 usually are far from the BS 10  such that the quality of uplink signals at the BS 10 is poor  e.g. low SNR and it especially needs extra information provided by the RS 20.
It should be understand that the above selection is not necessary. E.g. the 8 mobile terminals temporarily located in the cell administered by the BS 10 are always made the objects that need to be jointly processed by the RS 20  until one moves out the cell or moves to a location quite near the BS 10.
According to the example  when the RS 20 selects the above mobile terminals  the selection procedure preferably repeats periodically  which may be independent of the method and procedure showed in Fig. 2.
For the 3 paths of uplink signals transmitted from the 3 of 8 mobile terminals except for 31-35  the RS 20 may process them according to the conventional relay mode in L2 RSs  i.e. to demodulate  decode and filter the signals from noise  then to transmit them to the BS at orthogonal frequency after coding and modulating independently. Accordingly  the method that the BS 10 adopts to process the uplink signals from 3 mobile terminals is the same with the prior art. This article will not give unnecessary description. And the followings mainly make an introduction for the mobile terminals 31-35.
The corresponding functional module (not showing in the diagram) of the BS 10 buffers the 5 paths of uplink signals from mobile terminals 31-35 after receiving them  and waits for the check information transmitted from the RS 20 in next moment.
As to the RS20  it demodulates and decodes the 5 paths of uplink signals by using the demodulator and decoder 2002 in the first device 200 (i.e. implementing the S20 showed in fig.2)  to obtain 5 paths of decoded bit streams (see upper half of fig. 3). Wherein  for more generality  the number of mobile terminals  jointly processed in the RS 20 for multi-user detection in the BS 10  is set to M. Those skilled in the field can understand that the value should be set to 5 in the present embodiment. USER1-USERM correspond respectively to one of M paths of uplink signals transmitted from each mobile terminals  i.e. the decoded bit streams after demodulating and decoding. Wherein  taking User 1 as example  from U1,1 to U1,k mean the k decoded original bits  aimed at which the mobile terminal 1 implements channel encoding. While from U1,k+1?U1,l mean the check information of Turbo code.
The RS transmits M bit streams to the BS after encoding and modulating them (see lower half of Fig. 3). Wherein  taking RLY 1 as example  in the prior art  there is no difference in the first k bits between RLY 1 and USER 1. I.e. RLY 1=USER 1 and so on. This is because the RS 20 just decodes and forwards (DF) data to get the first order diversity gain.
According to an embodiment of the invention  Galois Field i.e. network coding scheme is applied. Wherein  one or more  e.g. 5 shift parameter groups are used for the 5 mobile terminals by shifting unit 2003 in the RS 20. Wherein  each shift parameter group comprises 5 (i.e. M described above) shift parameters. And specifically  the following operations are carried out for each shift parameter group: each of decoded bit streams USER1-USER5 is shifted based on the 5 shift parameters  in order to generate 5 shifted bit streams.
Without loss of generality  one shift parameter above is showed in Fig.4. Wherein  n is the index of the shift parameter groups  and m indicates this shift parameter in the parameter group is corresponding to which mobile terminals (or decoded bit streams). In the example  as described above  the value ranges of n and m are positive integers of 1-5  i.e. N=M=5.
In the universal shift matrix (i.e. shift parameters) of shift parameters  there are M columns and M rows (see fig. 4). Wherein  “1”s of each row are all in the n*mth column and “1” of the second row is in (n*m+1)th column and so on. Wherein  the shift parameter may be realized by a shift register.
The function of the shifting unit 2003 can also be expressed by the above formula (1):
Wherein  N is the number of shift parameter groups. means left cycle shifting bits of the mth decoded bit streams   by using the mth shift parameter in the nth shift parameter group. is the shifted bit stream obtained from shifting the .
Obviously  preferably  each shift parameter group should be different with each other  when using multiple shift parameter groups. It is actually ensured that different shifted bit streams are obtained after shifting the same decoded bit streams by using each shift parameter group. If multiple shift parameter groups are the same  the same M (i.e. 5) check bit streams are obtained after merging in the following S22  which has the same meaning as only one check bit stream for the BS 10.
According to Fig. 4 and formula (1)  a shift mode is obtained as showed in Fig. 5. Wherein  the row is corresponding to a shift parameter group and to a check bit stream generated finally. The column is corresponding to a shift parameter of the shift parameter group  and to a specific mobile terminal and a decoded bit stream. Each element in the table is the number of bits by which the bit stream is left cycle shifted under the action of a certain shift parameter of a certain shift parameter group.
Though the article makes an introduction of an example of shift parameter groups and shift parameters according to Fig. 4 and formula (1)  those skilled in the field can implement the shift operation of shifting unit 2003 to obtain N different or substantially different check bit streams  by using shift parameter groups and shift parameters in other forms without any creative work according to the teaching of the article. Wherein  the check bit streams substantially different mean the decoded bit streams  merged in merging unit 2004 after shifted by two different shift parameter groups  generate two check bit streams which are the same in form by chance.
Preferably  it should be ensured by shift parameters that there is no girth 4 circle based on network coded parity-check matrix. Otherwise it will reduce decoder performance  according to the decode theory.
According to the invention  the check information of Turbo code showed in Fig.3 may be involved or not in the shift operation described in the following. Without loss of generality  the introduction will not involve the check information of Turbo code in the shift operation.
According to the invention  advantageously  the RS 20 just needs to know how many mobile terminals will be in operations of shifting unit 2003  i.e. data (signals or information) of how many mobile terminals the RS20 will jointly process to provide check bit streams to the BS 10. Then each shift parameter group will be obtained simply. This is because the number of mobile terminals is the M mentioned in context again and again.
In order to make the BS 10 analyze correctly the check bit streams provided by the RS 20  the invention proposes many modes of realization.
1. The functionality of determining shift parameters  same with that of the RS 20  is provided to the BS 10. I.e. the BS 10 just needs to know how many mobile terminals the RS 20 jointly processes with shifting unit 2003 and merging unit 2004  then it can obtain the shift parameters which are similar but not limited as showed in Fig. 4.
2. The RS 20 reports in dedicated control channels to the BS 10 the shift parameters  e.g. it transmits the matrix showed in Fig. 4. Wherein  the third receiver 10011 of the obtaining unit 1001 receives the notice for parameter groups from the RS 20 and supplies it to the extractor 10012  and the later extracts each parameter group needed. Surely  since the method needs to transmit matrixes  the overheads of signaling are more.
Those skilled in the field may select one from the two methods above  according to their needs during actual realization of the invention.
Alternatively  the RS 20 may merge each shifted bit streams to one check bit stream with merging unit 2004  after obtaining 5 shifted bit streams by using 5 groups of shift parameters with shifting unit 2003. The RS 20 may also merge 5 decoded bit streams with merging unit 2004 after they are shifted by using one group of shift parameters with shifting unit 2003  then uses another group of shift parameters to repeat above operations until obtaining 5 check bit streams. Surely  in any time  the description of this article should not be understood as that the operation mode of shifting unit 2003 and merging unit 2004 is limited by the invention.
The following is an introduction of the operation of the merging unit 2004. According to a detailed embodiment of the invention  the RS 20 implements exclusive or to the 5 shifted bit streams obtained from each group of shift parameters to generate a check bit stream. The procedure is well shown in formula (2).
Wherein  RLY n is the check bit stream obtained by implementing exclusive or to M shifted bit streams by using the nth shift parameter group. And each of pn 1USER 1  pn 2USER 2 … pn mUSER m is shown in formula(1).
It can be seen that  in every bit stream obtained finally in merging unit 2004  each bit represents a result of parity check. Wherein  multiple bit streams participate in exclusive or are obtained from cycle shift. Consequently if the BS 10 knows the shift mode used by the RS 20  it will know each check bit of each check bit stream is the obtained check result of which bit of the original decoded bit streams.
The RS 20 transmits 5 check bit streams generated to the BS 10 by using the transmitter 2005  for assisting multi-user detection in BS 10.
In the example  N=M=5  i.e. 5 groups of shifted bit streams are obtained by using 5 shift parameter groups  and each group is merged into one check bit stream and finally 5 check bit streams are obtained. Then it""s better ensured less error probability when the BS 10 processes the 5 paths of uplink signals. Optionally  N may be less than M  i.e. the RS 20 may implement above operations by using 1 to 4 shift parameter groups. Then 1 to 4 check bit streams are provided to the BS 10. Compared to N=M case  this reducing check bit streams sacrifices some error rate (i.e. the error rate is higher). But some wireless resources are saved and may be allocated by BSs or RSs  so as to increase system transmission rate and reduce network delay.
Since the generation mode of check bit streams in the RS in the example is an encode mode of low density parity check(LDPC)  by using the executing device 1003 the BS 10 LDPC decodes the 5 uplink signals saved after receiving the 5 check bit streams from the RS 20. The final output LLR (log-likelihood ratio) value can be used as either decision value or the input of Turbo decoder. Wherein  in the example it is not considered as the input of Turbo decoder.
It needs to understand that the invention is not confined to the specific embodiment described above. Those skilled in this field may make a variety of variation or modification within the range of the appended claims.
What is claimed is:
1. A method  used for joint processing  in the RS of wireless relay network  wherein  the method comprises the following steps:
a. Demodulating and decoding respectively multiple paths of uplink signals from multiple mobile terminals  in order to generate multiple decoded bit streams:
b. Based on each one of one or more shift parameter groups  implementing respectively the following operations  wherein  each shift parameter group comprises M shift parameters:
i. Based on M shift parameters in the shift parameter group  shifting M decoded bit streams in the multiple decoded bit streams respectively  in order to generate M shifted bit streams;
ii. Merging the M shifted bit streams  in order to generate a check bit stream.
C. Sending to the BS the one or more check bit streams generated in step b  the check bit streams will be used to process the multiple paths of uplink signals in the BS.
2. A method according to claim 1  wherein  it comprises before the step b:
- Selecting  from the multi mobile terminals  M mobile terminals meeting preset conditions;
The step i still comprises:
- Based on the M shift parameters in the shift parameter group  respectively shifting the M decoded bit streams  from the multi decoded bit streams  corresponding to the M mobile terminals selected  in order to generate the M shifted bit streams.
3. A method according to claim 2  wherein  the steps which selects the M mobile terminals  from the multi mobile terminals  meeting preset conditions comprise:
- Selecting the M mobile terminals from the multi mobile terminals  wherein  the frame length of the M mobile terminals selected meet the preset condition  and the mobile terminals selected use the same modulation scheme.
4. A method according to claim 1  wherein  the step i is represented in the following formula:

Wherein  N is the number of the one or multi shift parameter groups  means using the mth shift parameter in the nth shift parameter group to make the mth decoded bit stream left circular shift by bits.
5. A method according to claim1  wherein  the step ii comprises:
- Implementing exclusive or processing to the M shifted bit streams  in order to generate the merged bit streams.
6. A method according to claim 1  wherein  the step comprises before the step a:
- Receiving the multiple paths of uplink signals  transmitted from the multiple mobile terminals by using orthogonal frequencies.
7. A method according to any one of claims from 1 to 6  wherein  the wireless relay network is long-term revolution network  or WiMAX network  or further revolution network of long-term revolution.
8. A method  in a BS of wireless relay network, used for processing uplink signals from multiple mobile terminals  wherein  the method comprises the following steps:
- obtaining one or more shift parameter groups;
Wherein  the one or multi shift parameter groups are used in the RS to shift process M decoded bit streams in decoded multiple bit streams which are demodulated and decoded from uplink signals of the multi mobile terminals.
Still comprises:
- Receiving one or more check bit streams transmitted from the RS;
- Based on the one or more check bit streams and the one or more shift parameter groups  processing the M paths of uplink signals from the M mobile terminals.
9. A method according to claim 8  wherein  the step of obtaining the one or more shift parameter groups comprises:
- Receiving a notice message of parameter groups from the RS  wherein it comprises the one or more shift parameter groups;
- Extracting the one or multi shift parameter groups from the notice message of parameter groups.
10. A method according to either claims 8 or 9  wherein  the wireless relay network is long-term revolution network  or WiMAX network  or further revolution network of long-term revolution.
11. A first device of jointly processing in RSs in wireless relay network. Wherein  it comprises:
Demodulator and decoder  for demodulating and decoding respectively multiple paths of uplink signals from multiple mobile terminals in order to generate multiple decoded bit streams;
Shifting unit and merging unit  which based on each one of one or more shift parameter groups implement respectively the following operations:
- shifting M decoded bit streams in the multiple decoded bit streams respectively  in order to generate M shifted bit streams  based on M shift parameters in each shift parameter group;
- Merging the M shifted bit streams in order to generate a check bit stream;
Transmitter  for sending to the BS the one or more check bit streams  the check bit streams will be used to process multi-user detection in the BS.
12. A second device  in BSs in wireless relay network  of receiving uplink signals from multiple mobile terminals  comprising:
Obtaining unit  for obtaining one or more shift parameter groups;
Wherein  the one or more shift parameter groups are used in the RS to shift process M decoded bit streams in decoded multiple bit streams which are demodulated and decoded from uplink signals of the multiple mobile terminals
further comprising:
second receiver  for receiving one or more check bit streams transmitted from the RS;
executing unit  for processes the M paths of uplink signals from the M mobile terminals based on the one or more check bit streams and the one or more shift parameter groups.
13. A relay station in wireless communication network  wherein  it comprises a first device according to claim 11.
14. A base station in wireless communication network  wherein  it comprises a second device according to claim 12.

Abstract
According to a detailed embodiment of the invention  the RS implements the following operations by using each of M shift parameter groups: Based on M shift parameters in the group  shifting respectively M decoded bit streams and merge the M shifted bit steams to get a check bit stream. Consequently M check bit streams are obtained by using M shift parameter groups. Then the RS transmits M check bit streams to the BS. The BS has received the M uplink signals from mobile terminals before and makes the M check bit streams as the check information of those uplink signals in order to check them better and reduce error rate. By adopting the method and device proposed by the invention  it is ensured in the low SNR regime error user rate or error block rate is more ideal in multi-user detection in the BS.