CN102487315B

CN102487315B - Multi-source multi-relay cooperation communication method, communication equipment and cooperation communication system

Info

Publication number: CN102487315B
Application number: CN201010573396.0A
Authority: CN
Inventors: 周小林; 杨彦东; 张成磊; 金莹; 魏岳军
Original assignee: Huawei Technologies Co Ltd
Current assignee: Huawei Technologies Co Ltd
Priority date: 2010-12-03
Filing date: 2010-12-03
Publication date: 2014-09-03
Anticipated expiration: 2030-12-03
Also published as: CN102487315A

Abstract

An embodiment of the invention provides a multi-source multi-relay cooperation communication method, communication equipment and a cooperation communication system. The multi-source multi-relay cooperation communication method comprises the following steps: the communication equipment receives a modulation signal sent by source user equipment at a first time slot; the communication equipment receives a modulation signal sent by the source user equipment at a second time slot and a modulation signal sent by relay user equipment; the modulation signal sent by the relay user equipment is an information bit sequence of the source user equipment recovered from the modulation signal sent by the source user equipment at the first time slot by the relay user equipment, according to the recovered information bit sequence, network coding is carried out, and data after the network coding is modulated to obtain a modulation signal; the communication equipment utilizes the modulation signal received at the first time slot and the modulation signal received at the second time slot and acquires an information bit sequence before modulation of the modulation signal sent by the source user equipment. According to a technical scheme provided by the invention, data transmission time can be saved.

Description

Multi-source multi-relay cooperative communication method, communication equipment and cooperative communication system

Technical Field

The invention relates to the technical field of communication, in particular to a multi-source multi-relay cooperative communication method, communication equipment and a cooperative communication system.

Background

In a wireless network, user-cooperative relay transmission is an effective technique for providing spatial diversity gain, which can improve system throughput, enhance transmission performance, and extend network coverage.

The conventional relay cooperative communication technology requires 4 slots in total. In the first time slot, the source user a sends data to the relay user and the base station. In the second time slot, the relay user forwards the received data packet of the source user a to the base station. In a similar way, in the third time slot, the source user B sends data to the relay user and the base station. And in the fourth time slot, the relay user forwards the received data of the source user B to the base station.

The network coding changes an information processing mode in the traditional relay cooperative communication, and the network coding is originally proposed to enable multicast transmission to reach the theoretical maximum transmission capacity so as to obtain better network throughput than the traditional routing mode. With the progress of research, network coding has great advantages in balancing network load, improving bandwidth utilization rate, improving network link robustness, reducing network management overhead, saving transmission energy consumption, increasing transmission security and the like, and can solve the problem that the traditional wireless technology cannot solve, improve wireless network transmission performance to a great extent, such as improving wireless transmission throughput and energy utilization efficiency, ensuring reliable transmission and security of wireless links and the like.

Wireless cooperative communication may also employ network coding techniques to achieve further improvements in network performance. Fig. 1 shows an orthogonal cooperative communication model based on network coding. As shown in fig. 1, in the first time slot (as shown by the thin solid line in fig. 1), the source user a sends its own data packet b₁And sending out. In the second time slot (shown by the dashed line in fig. 1), the source user B sends its own packet B₂And sending out. In the third slot (shown by the thick solid line in fig. 1), relay user C network-encodes the data received in the first two slots. For example: XOR processingAnd then, the relay user sends the data packet obtained by the XOR processing to a base station D, the base station properly processes the signals received by the 3 time slots, so that the user cooperation space diversity gain can be obtained, the data sent by the source user A and the source user B can be recovered, and one time slot can be saved by the orthogonal cooperation communication based on the network coding.

However, for the multi-source multi-relay system, the above orthogonal cooperative communication method based on network coding still needs to complete the cooperative communication process in three time slots.

Disclosure of Invention

The embodiment of the invention provides a multi-source multi-relay cooperative communication method, communication equipment and a network system, which can save data transmission time.

In view of this, the embodiment of the present invention provides:

a multi-source multi-relay cooperative communication method comprises the following steps:

the communication equipment receives a modulation signal transmitted by source user equipment in a first time slot;

the communication equipment receives the modulation signal sent by the source user equipment and the modulation signal sent by the relay user equipment in a second time slot; the modulation signal sent by the relay user equipment is a modulation signal obtained by recovering an information bit sequence of the source user equipment from the modulation signal sent by the source user equipment in a first time slot, carrying out network coding according to the recovered information bit sequence and modulating data obtained after the network coding;

the communication equipment uses the modulation signal received in the first time slot and the modulation signal received in the second time slot to obtain the information bit sequence of the modulation signal sent by the source user equipment before modulation.

A communication device, comprising:

a data receiving unit, configured to receive, in a first time slot, a modulated signal sent by a source user equipment, and receive, in a second time slot, the modulated signal sent by the source user equipment and a modulated signal sent by a relay user equipment; the modulation signal sent by the relay user equipment is a modulation signal obtained by recovering an information bit sequence of the source user equipment from the modulation signal sent by the source user equipment in a first time slot, carrying out network coding according to the recovered information bit sequence and modulating data obtained after the network coding;

and the decoding unit is used for acquiring the information bit sequence of the modulation signal sent by the source user equipment before modulation by using the modulation signal received by the receiving unit in the first time slot and the modulation signal received by the receiving unit in the second time slot.

A cooperative communication system, comprising: the communication device, the source user equipment and the plurality of relay user equipments described above, wherein,

the source user equipment is used for transmitting a modulation signal in a first time slot and transmitting the modulation signal in a second time slot;

the relay user equipment is used for recovering an information bit sequence of the source user equipment from a modulation signal sent by the source user equipment in a first time slot, performing network coding by using the recovered information bit sequence, modulating data obtained after the network coding, and sending the modulation signal obtained by modulation in a second time slot.

The communication equipment receives the modulation signal sent by the source user equipment in the first time slot, receives the modulation signal sent by the source user equipment and the modulation signal sent by the relay user equipment in the second time slot, and can acquire the information bit sequence before the modulation of the source user equipment by utilizing the modulation signals received in the two time slots, thereby saving the data transmission time.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

Fig. 1 is a flow chart of a multi-source multi-relay cooperative communication method provided by the prior art;

fig. 2 is a flowchart of a multi-source multi-relay cooperative communication method according to an embodiment of the present invention;

fig. 3 is a flowchart of another multi-source multi-relay cooperative communication method provided in an embodiment of the present invention;

fig. 4 is a flowchart of a decoding method in multi-source multi-relay cooperative communication according to an embodiment of the present invention;

fig. 5 is a schematic decoding diagram of a base station in multi-source multi-relay cooperative communication according to an embodiment of the present invention;

fig. 6 is a flowchart of an adaptive multi-source multi-relay cooperative communication method according to an embodiment of the present invention;

fig. 7 is a schematic diagram illustrating BER performance comparison between a network coding cooperative communication mechanism and a non-cooperative mechanism provided by an embodiment of the present invention;

fig. 8 is a performance diagram of a network coding cooperative communication mechanism based on different numbers of source user equipments according to an embodiment of the present invention;

fig. 9 is a schematic diagram illustrating the performance impact of the adaptive multi-source multi-user transmission method on the network coding cooperative communication mechanism according to the embodiment of the present invention;

fig. 10 is a schematic structural diagram of a communication device provided in an embodiment of the present invention;

fig. 11 is a schematic structural diagram of a decoding unit according to an embodiment of the present invention.

Detailed Description

Referring to fig. 2, an embodiment of the present invention provides a multi-source multi-relay cooperative communication method, which includes:

201. the communication device receives a modulated signal transmitted by a source user device in a first time slot.

202. The communication equipment receives the modulation signal sent by the source user equipment and the modulation signal sent by the relay user equipment in a second time slot; the modulation signal sent by the relay user equipment is a modulation signal obtained by recovering an information bit sequence of the source user equipment from the modulation signal sent by the source user equipment in the first time slot, performing network coding by using the recovered information bit sequence, and modulating data obtained after the network coding.

203. The communication equipment uses the modulation signal received in the first time slot and the modulation signal received in the second time slot to obtain the information bit sequence before the modulation of the modulation signal sent by the source user equipment. The obtained information bit sequence before modulation of the modulation signal sent by the source user equipment is original data which needs to be sent outwards by the source user.

The communication device in this embodiment may be a base station.

If the influence of the wireless channel on the modulated signals transmitted by the source user equipment and the relay user equipment is considered, the communication equipment receives a first distorted signal from the source user equipment in a first time slot in step 201; receiving a second distorted signal from the source user equipment and a distorted signal from the relay user equipment at a second time slot; the first distortion signal and the second distortion signal are signals of the same modulation signal which is respectively sent by the source user equipment in a first time slot and a second time slot and is distorted in the transmission process; the distorted signal from the relay user equipment is a signal obtained after the modulation signal sent by the relay user equipment in the second time slot is distorted in the transmission process, and in step 203, the communication equipment acquires the information bit sequence of the modulation signal sent by the source user equipment before modulation by using the distorted signal received in the first time slot and the distorted signal received in the second time slot.

Wherein, step 203 specifically comprises the following steps:

A. the communication equipment obtains a signal after de-interleaving of the external log-likelihood ratio corresponding to the modulation signal sent by the ith source user equipment of the first time slot by using the external log-likelihood ratio calculation formula and the modulation signal received in the first time slot; obtaining, by using a modulation signal received at a second time slot, a signal deinterleaved by an external log-likelihood ratio corresponding to a modulation signal sent by an ith source user equipment of the second time slot and a signal deinterleaved by an external log-likelihood ratio corresponding to a modulation signal sent by a plurality of relay user equipments which cooperate with the ith source user equipment to communicate at the second time slot;

B. the communication equipment performs network decoding on a signal subjected to de-interleaving by using an external log-likelihood ratio corresponding to a modulation signal sent by ith source user equipment in a first time slot and a signal subjected to de-interleaving by using an external log-likelihood ratio corresponding to a modulation signal sent by a plurality of relay user equipment in cooperation with the ith source user equipment in a second time slot to obtain a first network decoding result; and performing network decoding on the deinterleaved signals by using the external log-likelihood ratios corresponding to the modulation signals sent by the ith source user equipment in the second time slot and the deinterleaved signals corresponding to the external log-likelihood ratios corresponding to the modulation signals sent by the plurality of relay user equipment which is communicated with the ith source user equipment in cooperation with the second time slot to obtain a second network decoding result.

The first network decoding result is obtained as follows:

acquiring the sum of first type contributions of each relay user equipment for cooperating the communication of the ith source user equipment to the ith source user equipment; wherein, the first contribution of the relay user equipment cooperating with the ith source user equipment to the ith source user equipment in the first time slot is obtained by using the following formula:

wherein,carrying out forward error correction coding on the recovered information bit sequence of the ith source user equipment for the jth relay user equipment to obtain a signal;indicating a modulated signal transmitted by a source user equipment received at a first time slot communication deviceThe second time slot communication equipment receives the modulation signal transmitted by the relay user equipmentUnder the conditions of (a) under (b),a probability equal to 1;indicating a modulated signal transmitted by a source user equipment received at a first time slot communication deviceThe second time slot communication equipment receives the modulation signal transmitted by the relay user equipmentUnder the conditions of (a) under (b),a probability equal to 0.

If considered to be noneWhen the base station receives distorted signals from the source user equipment and the relay user equipment, a first contribution of the relay user equipment cooperating with the ith source user equipment to the ith source user equipment in the first time slot for communication may be represented as:wherein,representing a distorted signal received at a first time slot communication device from a source user deviceDistorted signal received by second time slot communication equipment from relay user equipmentUnder the conditions of (a) under (b),a probability equal to 1;representing a distorted signal received at a first time slot communication device from a source user deviceDistorted signal received by second time slot communication equipment from relay user equipmentUnder the conditions of (a) under (b),a probability equal to 0; it should be noted that:is equal to Is equal to

The second network decoding result is obtained as follows:

acquiring the sum of second contributions of each relay user equipment for cooperating the communication of the ith source user equipment to the ith source user equipment; wherein the second type of contribution of the relay user equipment cooperating with the ith source user equipment to the ith source user equipment in the second time slot is obtained by using the following formula:

wherein,carrying out forward error correction coding on the recovered information bit sequence of the ith source user equipment for the jth relay user equipment to obtain a signal;indicating a modulated signal transmitted by a source user equipment received at a second time slot communication deviceThe second time slot communication equipment receives the modulation signal transmitted by the relay user equipmentUnder the conditions of (a) under (b),a probability equal to 1;indicating a modulated signal transmitted by a source user equipment received at a second time slot communication deviceThe second time slot communication equipment receives the modulation signal transmitted by the relay user equipmentUnder the conditions of (a) under (b),a probability equal to 0.

If the base station receives a distorted signal from the source user equipment and the relay user equipment in consideration of the influence of the wireless channel on the modulated signals transmitted by the source user equipment and the relay user equipment, the second type of contribution of the relay user equipment cooperating with the ith source user equipment to the ith source user equipment in the second time slot can be expressed as follows:wherein,representing a distorted signal received at the second time slot communication device from the source user equipmentDistorted signal received by second time slot communication equipment from relay user equipmentUnder the conditions of (a) under (b),a probability equal to 1;representing a distorted signal received at the second time slot communication device from the source user equipmentDistorted signal received by second time slot communication equipment from relay user equipmentUnder the conditions of (a) under (b),a probability equal to 0. Wherein,is equal to Is equal to

C. The communication equipment calculates the sum of the deinterleaved signal corresponding to the external log-likelihood ratio value of the modulation signal sent by the ith source user equipment in the first time slot, the deinterleaved signal corresponding to the external log-likelihood ratio value of the modulation signal sent by the ith source user equipment in the second time slot, the first network decoding result and the second network decoding result, and performs channel decoding on the sum to obtain a first channel decoding result.

D. The communication equipment interweaves the first channel decoding result and the difference value of the signal after the de-interweaving of the external log likelihood ratio value corresponding to the modulation signal sent by the ith source user equipment of the first time slot to obtain a first interweaving result, and substitutes the first interweaving result into the external log likelihood ratio value calculation formula corresponding to the modulation signal sent by the ith source user equipment of the first time slot; decoding the signal after deinterleaving the external log-likelihood ratio value corresponding to the modulation signal sent by the ith source user equipment in the second time slot to obtain a second channel decoding result; interleaving the second channel decoding result with a difference value of a signal after de-interleaving of an external log-likelihood ratio corresponding to a modulation signal sent by ith source user equipment in a second time slot to obtain a second interleaving result, and substituting the second interleaving result into an external log-likelihood ratio calculation formula corresponding to the modulation signal sent by the ith source user equipment in the second time slot; and performing channel decoding on a signal subjected to de-interleaving by an external log-likelihood ratio corresponding to a modulation signal sent by relay user equipment for the communication of the ith source user equipment in cooperation with the second time slot to obtain a third channel decoding result, interleaving the third channel decoding result with a difference value of the signal subjected to de-interleaving by the external log-likelihood ratio corresponding to the modulation signal sent by the relay user equipment in the second time slot to obtain a third interleaving result, substituting the third interleaving result into an external log-likelihood ratio calculation formula corresponding to the modulation signal sent by the relay user equipment in the second time slot, and returning to the step A, B, C until an iteration termination condition is met. The condition for satisfying the iteration termination may be that a predetermined number of iterations is reached, or that a value calculated by an external log-likelihood ratio calculation formula corresponding to a modulation signal transmitted by the ith source user equipment tends to converge.

The communication equipment receives the modulation signal sent by the source user equipment in the first time slot, receives the modulation signal sent by the source user equipment and the modulation signal sent by the relay user equipment in the second time slot, and can acquire the information bit sequence before the modulation of the source user equipment by utilizing the signals received in the two time slots, thereby saving the data transmission time.

In order to make the technical scheme provided by the invention clearer, the following embodiments describe the technical scheme provided by the invention in detail:

fig. 3 shows a multi-source multi-relay cooperative communication method provided in an embodiment of the present invention, where the method assumes that a cooperative communication system includes N pieces of user equipment, where: source user equipment set taggingI is more than or equal to 1 and less than or equal to K. In addition, the relay user equipment set is marked asJ is more than or equal to 1 and less than or equal to (N-K), each user equipment uses a single antenna, and the method specifically comprises the following steps:

301. in the first time slot, K pieces of source user equipment broadcast modulation signals, and the relay user equipment recovers the information bit sequence before modulation of the modulation signals broadcast by the source user equipment.

In particular, K source user equipments are arranged to the information bit sequenceCoding to obtain a sequenceWherein L is_dFor the frame length of the information bit sequence, L_cTo encode the frame length of the obtained sequence, specifically, Forward Error Correction (FEC) coding technology may be used for encoding, and Turbo code may also be used for encoding. Then, the sequence obtained by coding is interleaved and modulated by an interleaver and a modulator to obtain a modulation signal, and the modulation signal is broadcasted.

The relay user equipment receives the modulation signals broadcast by K pieces of source user equipment, and recovers an information bit sequence before modulation of the modulation signals sent by the source user equipment by using an interleaved-multiple-access (IDMA) iterative multi-user detection method, and the information bit sequence is recorded asWherein j is more than or equal to 1 and less than or equal to (N-K), and i is more than or equal to 1 and less than or equal to K.

Since the modulated signals are transmitted by K source user equipments in a broadcast manner, the base station receives a first distorted signal corresponding to the modulated signals, and the first distorted signal received by the base station in this step is a signal obtained by distorting the modulated signals broadcast by the source user equipments in the first time slot during transmission. Specifically, the base station receives the signal of1≤l≤L_s，L_SIs the length of a symbol of a frame,is Additive White Gaussian Noise (AWGN) generated at the base station with a mean of 0 and a variance ofRepresenting the block fading channel between the ith source user equipment and the base station,a modulated signal broadcast for the ith source user equipment of the first time slot,is a first distorted signal.

302. And in the second time slot, the source user equipment broadcasts the modulation signal again, the relay user equipment uses linear network coding to code, interweave and modulate the recovered information bit sequence of the source user equipment, and the modulated modulation signal is broadcast.

In the time slot, the relay user equipment encodes the recovered information bit sequence of the source user equipment to obtain a sequenceThen, using linear network coding, the coded bits are xor-ed,wherein j is not less than 1 and not more than (N-K), ifOrder toWherein A is_jAnd selecting a set of source user equipment for network coding for the jth relay user equipment, wherein the relay user equipment can select specific source user equipment for network coding, specifically all the source user equipment can be selected, or part of the source user equipment can be selected. And the N-K relay user equipment interweaves and modulates the XOR operation result and then broadcasts the modulation signal.

In the second time slot, the source user equipment broadcasts its modulated signal againIn this time slot, the base station receives a second distorted signal from the source user equipment and a distorted signal from the relay device, where the second distorted signal from the source user equipment is a signal obtained by distorting the modulated signal transmitted by the source user equipment in the second time slot during transmission, and the distorted signal from the relay device is a signal obtained by distorting the modulated signal transmitted by the relay user equipment in the second time slot during transmission, specifically, the signal received by the base station in this time slot is represented as:wherein,a modulated signal broadcast in the second time slot for the ith source user equipment,for a block-fading channel between the ith source user equipment and the base station,is a second distorted signal;for the modulated signal broadcast by the jth relay user equipment in the second time slot,for the flat block fading channel between the jth relay user equipment and the base station,is a distorted signal from the relay user equipment;additive white Gaussian noise generated by the base station with a mean of 0 and a variance of

303. And the base station obtains the information bit sequence before modulation of the source user equipment according to the signal received by the first time slot and the signal received by the second time slot.

As shown in fig. 4, the step 303 specifically includes:

401. in the base station, a soft multi-user detection algorithm similar to chip-level Gaussian distribution is utilized, and signals received by a first time slot are utilized to obtain an external log-likelihood ratio value corresponding to a modulation signal sent by ith source user equipment of the first time slotDe-interleaving external log-likelihood ratio corresponding to modulation signal sent by ith source user equipment in first time slot to obtain de-interleaved signal

Specifically, according to the following formula (1), the modulated signal sent by the ith source user equipment in the first time slot is obtained by using a soft multi-user detection algorithm with approximate chip-level gaussian distribution and using the following external log-likelihood ratio calculation formulaCorresponding external log-likelihood ratio values.

<math> <mrow> <msub> <mi>e</mi> <mi>MUD</mi> </msub> <mrow> <mo>(</mo> <msubsup> <mi>x</mi> <mi>i</mi> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>=</mo> <mfrac> <msubsup> <mrow> <mn>2</mn> <mi>h</mi> </mrow> <mi>i</mi> <mi>SD</mi> </msubsup> <mrow> <munder> <mi>Σ</mi> <mrow> <msup> <mi>i</mi> <mo>′</mo> </msup> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <msup> <mrow> <mo>|</mo> <msubsup> <mi>h</mi> <msup> <mi>i</mi> <mo>′</mo> </msup> <mi>SD</mi> </msubsup> <mo>|</mo> </mrow> <mn>2</mn> </msup> <mi>Var</mi> <mrow> <mo>(</mo> <msubsup> <mi>x</mi> <msup> <mi>i</mi> <mo>′</mo> </msup> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>+</mo> <msubsup> <mi>σ</mi> <mn>1</mn> <mn>2</mn> </msubsup> </mrow> </mfrac> <mrow> <mo>(</mo> <msubsup> <mi>r</mi> <mn>1</mn> <mi>SD</mi> </msubsup> <mo>-</mo> <munder> <mi>Σ</mi> <mrow> <msup> <mi>i</mi> <mo>′</mo> </msup> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <mi>E</mi> <mrow> <mo>(</mo> <msubsup> <mi>x</mi> <msup> <mi>i</mi> <mo>′</mo> </msup> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>)</mo> </mrow> <mo>,</mo> </mrow> </math>

<math> <mrow> <mo>&ForAll;</mo> <mi>i</mi> <mo>,</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>1</mn> <mo>)</mo> </mrow> </mrow> </math>

Wherein, fed back by the first channel decoding unitOne a posteriori information of (a), Var (-) and E (-) indicates the variance and mean, respectively. Wherein,wherein,means any one of

The method comprises the steps that a soft multi-user detection algorithm with approximate chip-level Gaussian distribution is utilized to obtain an external log-likelihood ratio value corresponding to a modulation signal sent by ith source user equipment of a first time slot, the external log-likelihood ratio value corresponding to the modulation signal sent by the ith source user equipment of the first time slot is obtained by a first multi-user detection MUD unit in a base station, and the deinterleaving operation of the external log-likelihood ratio value corresponding to the modulation signal sent by the ith source user equipment of the first time slot is executed by a first deinterleaving unit in the base station.

402. In the base station, a soft multi-user detection algorithm similar to chip-level Gaussian distribution is utilized, and a signal received by a second time slot is utilized to obtain an external log-likelihood ratio value corresponding to a modulation signal sent by ith source user equipment of the second time slotDe-interleaving external log-likelihood ratio corresponding to modulation signal sent by ith source user equipment in second time slot to obtain de-interleaved signal

In a similar manner to step 401, the modulated signal transmitted by the ith source ue in the second slot is obtainedCorresponding external log-likelihood ratio values.

In the base station, the soft multi-user detection algorithm with approximate chip-level gaussian distribution is used to obtain the external log-likelihood ratio corresponding to the modulation signal sent by the ith source user equipment in the second time slot, which is executed by the second multi-user detection MUD unit in the base station, and the operation of deinterleaving the external log-likelihood ratio corresponding to the modulation signal sent by the ith source user equipment in the second time slot is executed by the second deinterleaving unit in the base station.

403. In the base station, a soft multi-user detection algorithm similar to chip-level Gaussian distribution is utilized, and signals received by a second time slot are utilized to obtain an external log-likelihood ratio value corresponding to a modulation signal sent by relay user equipment for communication of the ith source user equipment in cooperation with the second time slotDe-interleaving external log-likelihood ratios corresponding to modulation signals sent by relay user equipment to respectively obtain de-interleaved signals

Received in the second time slot is obtained in a similar manner to step 401The outer log-likelihood ratio values of (a) deinterleave the signal.

In the base station, the soft multi-user detection algorithm with approximate chip-level gaussian distribution is used to obtain the external log-likelihood ratio corresponding to the modulation signal sent by the relay user equipment for the communication of the second time slot cooperation ith source user equipment, which is executed by a third multi-user detection (MUD) unit in the base station, and the deinterleaving operation on the external log-likelihood ratio corresponding to the modulation signal sent by the relay user equipment is executed by a third deinterleaving unit.

It should be noted that, steps 401 and 403 have no chronological sequence and can be executed simultaneously.

404. Deinterleaved signal by using external log-likelihood ratio value corresponding to modulation signal sent by ith source user equipment in first time slotA signal de-interleaved by an external log-likelihood ratio value corresponding to a modulation signal sent by relay user equipment which is in communication with the ith source user equipment in cooperation with a second time slotPerforming network decoding to obtain a first network decoding result

The network decoding operation of this step may be specifically performed by the first network codec unit.

Specifically, according to the following formula (2), a first contribution of the jth relay user equipment to the ith source user equipment is obtainedA value of (d);

<math> <mrow> <mo>&ForAll;</mo> <mi>i</mi> <mo>,</mo> <mi>j</mi> <mo>,</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>2</mn> <mo>)</mo> </mrow> </mrow> </math>

wherein, coding the restored information bit sequence of the ith source user equipment for the jth relay user equipment to obtain a signal;representing a first distorted signal received at a first time slot base station from a source user equipmentDistorted signals received by the second time slot base station from the relay user equipmentUnder the conditions of (a) under (b),a probability equal to 1;representing a first distorted signal received at a first time slot base station from a source user equipmentDistorted signals received by the second time slot base station from the relay user equipmentUnder the conditions of (a) under (b),a probability equal to 0;

wherein,

<math> <mrow> <mi>α</mi> <mo>=</mo> <mfrac> <mrow> <munder> <munder> <mi>Σ</mi> <mrow> <mn>1</mn> <mo>≤</mo> <mi>l</mi> <mo>≤</mo> <mi>K</mi> </mrow> </munder> <mrow> <mi>l</mi> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <mi>exp</mi> <mrow> <mo>(</mo> <msub> <mi>L</mi> <mi>MUD</mi> </msub> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <mi>l</mi> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>)</mo> </mrow> <mo>+</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>+</mo> <munder> <munder> <mi>Σ</mi> <mrow> <mn>1</mn> <mo>≤</mo> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>≤</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>≤</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> </msub> <mo>≤</mo> <mi>K</mi> </mrow> </munder> <mrow> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> </msub> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <mi>exp</mi> <mrow> <mo>(</mo> <munderover> <mi>Σ</mi> <mrow> <mi>m</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> </munderover> <msub> <mi>L</mi> <mi>MUD</mi> </msub> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <msub> <mi>l</mi> <mi>m</mi> </msub> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>)</mo> </mrow> </mrow> <mrow> <mn>1</mn> <mo>+</mo> <munder> <munder> <mi>Σ</mi> <mrow> <mn>1</mn> <mo>≤</mo> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>≤</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>≤</mo> <mi>K</mi> </mrow> </munder> <mrow> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <mi>exp</mi> <mrow> <mo>(</mo> <munderover> <mi>Σ</mi> <mrow> <mi>m</mi> <mo>=</mo> <mn>1</mn> </mrow> <mn>2</mn> </munderover> <msub> <mi>L</mi> <mi>MID</mi> </msub> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <msub> <mi>l</mi> <mi>m</mi> </msub> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>)</mo> </mrow> <mo>+</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>+</mo> <munder> <munder> <mi>Σ</mi> <mrow> <mn>1</mn> <mo>≤</mo> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>≤</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>≤</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>2</mn> </mrow> </msub> <mo>≤</mo> <mi>K</mi> </mrow> </munder> <mrow> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>2</mn> </mrow> </msub> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <mi>exp</mi> <mrow> <mo>(</mo> <munderover> <mi>Σ</mi> <mrow> <mi>m</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>2</mn> </mrow> </munderover> <msub> <mi>L</mi> <mi>MUD</mi> </msub> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <msub> <mi>l</mi> <mi>m</mi> </msub> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>)</mo> </mrow> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

the derivation of equation (2) is as follows:

L_{MUD}^{S} (c_{i}^{j}) = \log \frac{P (c_{i}^{j} = 1 / R)}{P (c_{i}^{j} = 0 / R)}

<math> <mrow> <mo>=</mo> <mi>log</mi> <mfrac> <mrow> <mi>P</mi> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <mi>j</mi> <mi>R</mi> </msubsup> <mo>&CirclePlus;</mo> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <mn>1</mn> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mn>2</mn> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mrow> <mi>i</mi> <mo>-</mo> <mn>1</mn> </mrow> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mrow> <mi>i</mi> <mo>+</mo> <mn>1</mn> </mrow> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mi>K</mi> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>=</mo> <mn>1</mn> <mo>/</mo> <msubsup> <mi>r</mi> <mn>1</mn> <mi>SD</mi> </msubsup> <mo>,</mo> <msubsup> <mi>r</mi> <mn>2</mn> <mi>RD</mi> </msubsup> <mo>)</mo> </mrow> </mrow> <mrow> <mi>P</mi> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <mi>j</mi> <mi>R</mi> </msubsup> <mo>&CirclePlus;</mo> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <mn>1</mn> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mn>2</mn> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mrow> <mi>i</mi> <mo>-</mo> <mn>1</mn> </mrow> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mrow> <mi>i</mi> <mo>+</mo> <mn>1</mn> </mrow> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mi>K</mi> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>=</mo> <mn>0</mn> <mo>/</mo> <msubsup> <mi>r</mi> <mn>1</mn> <mi>SD</mi> </msubsup> <mo>,</mo> <msubsup> <mi>r</mi> <mn>2</mn> <mi>RD</mi> </msubsup> <mo>)</mo> </mrow> </mrow> </mfrac> </mrow> </math>

wherein,

= \frac{P (\frac{1 - {(- 1)}^{c_{1}^{S} + c_{2}^{S} + . . . + c_{i - 1}^{S} + c_{i + 1}^{S} + . . . + c_{K}^{S}}}{2} = 1 / r_{1}^{SD})}{P (\frac{1 - {(- 1)}^{c_{1}^{S} + c_{2}^{S} + . . . + c_{i - 1}^{S} + c_{i + 1}^{S} + . . . + c_{K}^{S}}}{2} = 0 / r_{1}^{SD})}

<math> <mrow> <mtext>=</mtext> <mfrac> <mrow> <munder> <munder> <mi>Σ</mi> <mrow> <mn>1</mn> <mo>≤</mo> <mi>l</mi> <mo>≤</mo> <mi>K</mi> </mrow> </munder> <mrow> <mi>l</mi> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <msub> <mi>A</mi> <mi>l</mi> </msub> <mo>+</mo> <munder> <munder> <mi>Σ</mi> <mrow> <mn>1</mn> <mo>≤</mo> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>≤</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>≤</mo> <msub> <mi>l</mi> <mn>3</mn> </msub> <mo>≤</mo> <mi>K</mi> </mrow> </munder> <mrow> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <msub> <mi>l</mi> <mn>3</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <msub> <mi>A</mi> <msub> <mi>l</mi> <mn>1</mn> </msub> </msub> <msub> <mi>A</mi> <msub> <mi>l</mi> <mn>2</mn> </msub> </msub> <msub> <mi>A</mi> <msub> <mi>l</mi> <mn>3</mn> </msub> </msub> <mo>+</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>+</mo> <munder> <munder> <mi>Σ</mi> <mrow> <mn>1</mn> <mo>≤</mo> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>≤</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>≤</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> </msub> <mo>≤</mo> <mi>K</mi> </mrow> </munder> <mrow> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> </msub> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <msub> <mi>A</mi> <msub> <mi>l</mi> <mn>1</mn> </msub> </msub> <msub> <mi>A</mi> <msub> <mi>l</mi> <mn>2</mn> </msub> </msub> <mo>.</mo> <mo>.</mo> <mo>.</mo> <msub> <mi>A</mi> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> </msub> </msub> </mrow> <mrow> <mn>1</mn> <mo>+</mo> <munder> <mrow> <munder> <mi>Σ</mi> <mrow> <mn>1</mn> <mo>≤</mo> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>≤</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>≤</mo> <mi>K</mi> </mrow> </munder> </mrow> <mrow> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <msub> <mi>A</mi> <msub> <mi>l</mi> <mn>1</mn> </msub> </msub> <msub> <mi>A</mi> <msub> <mi>l</mi> <mn>2</mn> </msub> </msub> <mo>+</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>+</mo> <munder> <munder> <mi>Σ</mi> <mrow> <mn>1</mn> <mo>≤</mo> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>≤</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>≤</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>2</mn> </mrow> </msub> <mo>≤</mo> <mi>K</mi> </mrow> </munder> <mrow> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>2</mn> </mrow> </msub> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <msub> <mi>A</mi> <msub> <mi>l</mi> <mn>1</mn> </msub> </msub> <msub> <mi>A</mi> <msub> <mi>l</mi> <mn>2</mn> </msub> </msub> <mo>.</mo> <mo>.</mo> <mo>.</mo> <msub> <mi>A</mi> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>2</mn> </mrow> </msub> </msub> </mrow> </mfrac> </mrow> </math>

<math> <mrow> <mo>=</mo> <mfrac> <mrow> <munder> <munder> <mi>Σ</mi> <mrow> <mn>1</mn> <mo>≤</mo> <mi>l</mi> <mo>≤</mo> <mi>K</mi> </mrow> </munder> <mrow> <mi>l</mi> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <mi>exp</mi> <mrow> <mo>(</mo> <msub> <mi>L</mi> <mi>MUD</mi> </msub> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <mi>l</mi> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>)</mo> </mrow> <mo>+</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>+</mo> <munder> <munder> <mi>Σ</mi> <mrow> <mn>1</mn> <mo>≤</mo> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>≤</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>≤</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> </msub> <mo>≤</mo> <mi>K</mi> </mrow> </munder> <mrow> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> </msub> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <mi>exp</mi> <mrow> <mo>(</mo> <munderover> <mi>Σ</mi> <mrow> <mi>m</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> </munderover> <msub> <mi>L</mi> <mi>MUD</mi> </msub> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <msub> <mi>l</mi> <mi>m</mi> </msub> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>)</mo> </mrow> </mrow> <mrow> <mn>1</mn> <mo>+</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>+</mo> <munder> <munder> <mi>Σ</mi> <mrow> <mn>1</mn> <mo>≤</mo> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>≤</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>≤</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>2</mn> </mrow> </msub> <mo>≤</mo> <mi>K</mi> </mrow> </munder> <mrow> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>2</mn> </mrow> </msub> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <mi>exp</mi> <mrow> <mo>(</mo> <munderover> <mi>Σ</mi> <mrow> <mi>m</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>2</mn> </mrow> </munderover> <msub> <mi>L</mi> <mi>MUD</mi> </msub> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <msub> <mi>l</mi> <mi>m</mi> </msub> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>)</mo> </mrow> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

wherein,l is not less than 1 and not more than K, l is not equal to i, if 1≤l≤K。

405. Deinterleaved signal by using external log-likelihood ratio value corresponding to modulation signal sent by ith source user equipment in second time slotDeinterleaved signals corresponding to external log-likelihood ratios of modulation signals sent by a plurality of relay user equipment which are communicated with the ith source user equipment in cooperation with a second time slotPerforming network decoding to obtain a second network decoding result

The network transcoding operation of this step may be specifically performed by the second network codec unit.

Specifically, the second contribution of the jth relay user equipment to the ith source user equipment is obtained according to the following formulaA value of (d);

<math> <mrow> <mo>=</mo> <mi>log</mi> <mfrac> <mrow> <mi>P</mi> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <mi>j</mi> <mi>R</mi> </msubsup> <mo>&CirclePlus;</mo> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <mn>1</mn> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mn>2</mn> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mrow> <mi>i</mi> <mo>-</mo> <mn>1</mn> </mrow> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mrow> <mi>i</mi> <mo>+</mo> <mn>1</mn> </mrow> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mi>K</mi> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>=</mo> <mn>1</mn> <mo>/</mo> <msubsup> <mi>r</mi> <mn>1</mn> <mi>RD</mi> </msubsup> <mo>,</mo> <msubsup> <mi>r</mi> <mn>2</mn> <mi>RD</mi> </msubsup> <mo>)</mo> </mrow> </mrow> <mrow> <mi>P</mi> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <mi>j</mi> <mi>R</mi> </msubsup> <mo>&CirclePlus;</mo> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <mn>1</mn> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mn>2</mn> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mrow> <mi>i</mi> <mo>-</mo> <mn>1</mn> </mrow> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mrow> <mi>i</mi> <mo>+</mo> <mn>1</mn> </mrow> <mi>S</mi> </msubsup> <mo>&CirclePlus;</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>&CirclePlus;</mo> <msubsup> <mi>c</mi> <mi>K</mi> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>=</mo> <mn>0</mn> <mo>/</mo> <msubsup> <mi>r</mi> <mn>1</mn> <mi>RD</mi> </msubsup> <mo>,</mo> <msubsup> <mi>r</mi> <mn>2</mn> <mi>RD</mi> </msubsup> <mo>)</mo> </mrow> </mrow> </mfrac> </mrow> </math>

wherein,representing a second distorted signal received at the second time slot base station from the source user equipmentDistorted signals received by the second time slot base station from the relay user equipmentUnder the conditions of (a) under (b),a probability equal to 1;representing a second distorted signal received at the second time slot base station from the source user equipmentDistorted signals received by the second time slot base station from the relay user equipmentUnder the conditions of (a) under (b),a probability equal to 0.

= \frac{P (\frac{1 - {(- 1)}^{c_{1}^{S} + c_{2}^{S} + . . . + c_{i - 1}^{S} + c_{i + 1}^{S} + . . . + c_{K}^{S}}}{2} = 1 / r_{2}^{SD})}{P (\frac{1 - {(- 1)}^{c_{1}^{S} + c_{2}^{S} + . . . + c_{i - 1}^{S} + c_{i + 1}^{S} + . . . + c_{K}^{S}}}{2} = 0 / r_{2}^{SD})}

<math> <mrow> <mo>=</mo> <mfrac> <mrow> <munder> <munder> <mi>Σ</mi> <mrow> <mn>1</mn> <mo>≤</mo> <mi>l</mi> <mo>≤</mo> <mi>K</mi> </mrow> </munder> <mrow> <mi>l</mi> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <mi>exp</mi> <mrow> <mo>(</mo> <msubsup> <mi>L</mi> <mi>MUD</mi> <mo>′</mo> </msubsup> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <mi>l</mi> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>)</mo> </mrow> <mo>+</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>+</mo> <munder> <munder> <mi>Σ</mi> <mrow> <mn>1</mn> <mo>≤</mo> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>≤</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>≤</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> </msub> <mo>≤</mo> <mi>K</mi> </mrow> </munder> <mrow> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> </msub> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <mi>exp</mi> <mrow> <mo>(</mo> <munderover> <mi>Σ</mi> <mrow> <mi>m</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>1</mn> </mrow> </munderover> <msubsup> <mi>L</mi> <mi>MUD</mi> <mo>′</mo> </msubsup> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <msub> <mi>l</mi> <mi>m</mi> </msub> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>)</mo> </mrow> </mrow> <mrow> <mn>1</mn> <mo>+</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>+</mo> <munder> <munder> <mi>Σ</mi> <mrow> <mn>1</mn> <mo>≤</mo> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>≤</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>≤</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>2</mn> </mrow> </msub> <mo>≤</mo> <mi>K</mi> </mrow> </munder> <mrow> <msub> <mi>l</mi> <mn>1</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <msub> <mi>l</mi> <mn>2</mn> </msub> <mo>&NotEqual;</mo> <mi>i</mi> <mo>,</mo> <mo>.</mo> <mo>.</mo> <mo>.</mo> <mo>,</mo> <msub> <mi>l</mi> <mrow> <mi>K</mi> <mo>-</mo> <mn>2</mn> </mrow> </msub> <mo>&NotEqual;</mo> <mi>i</mi> </mrow> </munder> <mi>exp</mi> <mrow> <mo>(</mo> <munderover> <mi>Σ</mi> <mrow> <mi>m</mi> <mo>=</mo> <mn>1</mn> </mrow> <mrow> <mi>K</mi> <mo>-</mo> <mn>2</mn> </mrow> </munderover> <msubsup> <mi>L</mi> <mi>MUD</mi> <mo>′</mo> </msubsup> <mrow> <mo>(</mo> <msubsup> <mi>c</mi> <msub> <mi>l</mi> <mi>m</mi> </msub> <mi>S</mi> </msubsup> <mo>)</mo> </mrow> <mo>)</mo> </mrow> </mrow> </mfrac> <mo>,</mo> </mrow> </math>

It should be noted that steps 404 and 405 do not have a chronological sequence, and may be executed simultaneously.

406. The base station de-interleaves the external log likelihood ratio value corresponding to the modulation signal sent by the ith source user equipment in the first time slot,The signal, the first network decoding result and the second network decoding result after the de-interleaving of the external log-likelihood ratio corresponding to the modulation signal sent by the ith source user equipment in the second time slot are summed to obtain the external log-likelihood ratio of the ith source user equipment

Specifically, the external log-likelihood ratio of the ith source ue is obtained by using the following formula (3):

<math> <mrow> <mo>&ForAll;</mo> <mi>i</mi> <mo>.</mo> <mo>-</mo> <mo>-</mo> <mo>-</mo> <mrow> <mo>(</mo> <mn>3</mn> <mo>)</mo> </mrow> </mrow> </math>

407. external log-likelihood ratio of base station to ith source user equipmentChannel decoding is carried out to obtain a first channel decoding result, and the first channel decoding result and the difference value of the signals after the de-interleaving of the external log likelihood ratio value corresponding to the modulation signal sent by the ith source user equipment in the first time slot are obtainedInterweaving to obtain a first interweaving resultThe first interleaving resultAnd substituting the modulation signal into an external log-likelihood ratio calculation formula corresponding to the modulation signal sent by the ith source user equipment in the first time slot until an iteration termination condition is reached.

The operation of channel decoding in this step may be performed by a first channel decoding unit in the base station.

408. The base station corresponds to the external log-likelihood ratio value of the modulation signal sent by the ith source user equipment of the second time slotDeinterleaved signalPerforming channel decoding to obtain a second channel decoding result; deinterleaving the second channel decoding result and the external log-likelihood ratio value corresponding to the modulation signal sent by the ith source user equipment in the second time slotDifference of (2)Interweaving to obtain a second interweaving resultAnd substituting the second interleaving result into an external log-likelihood ratio calculation formula corresponding to a modulation signal sent by the ith source user equipment in the second time slot until an iteration termination condition is reached.

The operation of channel decoding in this step may be performed by a second channel decoding unit in the base station.

409. The base station de-interleaves the external log-likelihood ratio value corresponding to the modulation signal sent by the relay user equipment which is used for the communication of the ith source user equipment in cooperation with the second time slotChannel decoding is carried out to obtain a third channel decoding result, and the third channel decoding result and the difference value of the signal after the de-interleaving of the external log-likelihood ratio value corresponding to the modulation signal sent by the relay user equipment in the second time slot are obtainedInterweaving to obtain a third interweaving resultSubstituting the third interleaving result into the modulation signal sent by the second time slot relay user equipmentAnd calculating the external log-likelihood ratio corresponding to the number until the iteration termination condition is reached.

It should be noted that, the steps 407 and 409 have no chronological sequence and can be executed simultaneously.

The operation of channel decoding in this step may be performed by a third channel decoding unit in the base station.

In the embodiment of the invention, a base station receives a first distortion signal from source user equipment in a first time slot, receives a second distortion signal from the source user equipment and a distortion signal from relay user equipment in a second time slot, wherein the first distortion signal and the second distortion signal are signals generated after the same modulation signal sent by the source user equipment in the first time slot and the second time slot respectively is distorted in the transmission process; the distorted signal from the relay user equipment is a signal after the modulated signal sent by the relay user equipment in the second time slot is distorted in the transmission process, and the base station can acquire the information bit sequence before the modulation of the source user equipment by using the signals received by the two time slots, so that the data transmission time is saved; meanwhile, the sensitivity of the system can be improved by a multi-relay cooperative transmission mode, and higher diversity gain can be obtained; further, relay transmission can be completed for a plurality of source user equipments under the condition of only one relay user equipment, and obvious error rate improvement is obtained.

The diversity gain of the whole system can be increased due to the increase of the relay user equipment, and the number of the source user equipment which is cooperated by each relay user equipment can be reduced along with the increase of the relay user equipment, namely, each relay user equipment can only carry out network coding combination on information sequences recovered by M (M < K) source user equipment; however, the throughput of the whole system is also reduced by the increase of the relay user equipments, and therefore, the number of the source user equipments which cooperate in the network coding of each relay user equipment is required to be determined according to the actual system situation.

In addition, in general, it is considered that the distance between the relay user equipment and the source user equipment is very short, the channel environment is good, the error rate of decoding the modulated signal broadcast by the source user equipment by the relay user equipment is low, and the receiving performance is ideal. However, due to the mobility of the source ue, the relay ue may be far away from the source ue, and in this case, if the modulated signal broadcasted by the source ue is forcibly decoded and network-coded, the performance of the system may be poor. Therefore, it can be considered that when the relay user equipment cannot decode the modulation signal broadcast by the source user equipment well, the network coding is not performed in the second time slot, but the modulation signal received in the first time slot is directly transmitted in a separate time slot after the second time slot.

Based on the above two aspects, the application provides a self-adaptive multi-source multi-user cooperative transmission method, which specifically includes:

601. when a system initially operates, selecting a network element as relay user equipment, and setting that the relay user equipment can perform network coding, wherein the number K' of the relay user equipment capable of performing network coding is 1; the number K ″, of relay user equipments which directly forward data, is 0.

602. The new relay user equipment judges whether the receiving error rate of the new relay user equipment is smaller than a threshold value, if so, 603 is executed; if not, 607 is performed.

And when the system is initially operated, the selected relay user equipment is the new relay user equipment. The receiving error rate refers to an error rate of decoding, by the new relay device, the modulation signal transmitted by the source user equipment.

603. The new relay user equipment reports the receiving error rate to the base station, the base station determines the number of the source user equipment cooperated by the new relay user equipment according to the receiving error rate reported by the new relay user equipment and the position of the relay user equipment, and sends indication information indicating the number of the source user equipment cooperated by the new relay user equipment to the new relay user equipment.

604. The new relay user equipment decodes the modulation signals received by the first time slot and sent by the source user equipment with the corresponding number according to the indication information indicating the number of the source user equipment which is cooperated by the new relay user equipment, restores the information bit sequence, performs network coding, interleaving and modulation processing on the restored information bit sequence, sends the modulation signals in the second time slot, and executes 607.

605. And the new relay user equipment sends the modulation signals sent by the corresponding number of the source user equipment to the base station in a time slot after the second time slot.

606. The base station sets K' -1 and K ═ K ″ + 1.

607. The base station determines whether K' + K "is less than or equal to K-1, if so, 608 is executed, and if not, the process is ended.

608. And the base station judges whether the receiving error rate of the base station is less than the preset error rate, if so, the 609 is executed, and if not, the process is ended.

Specifically, the base station may determine the reception error rate according to the information bit sequence of the source user equipment obtained by decoding.

Optionally, this step may also determine whether the system capacity reaches a predetermined value, and if so, execute step 609, where the system capacity refers to the number of bits per second per HZ transmitted by the system.

609. The base station notifies the non-relay node in the system as a new relay node, sets K '═ K' +1, and returns to execute step 602.

It should be noted that, if the base station does not determine the number of the source user equipments which it cooperates with for the new relay user equipment, each relay user equipment may be respectively the source user equipmentIndividual source ues communicating cooperatively, i.e. recovered per relay ue pairAnd the information bit sequence of the source user equipment is subjected to network coding, interleaving and modulation, and then a modulation signal is sent. Through simulation, when the total number K' + K "of the relay user equipments is equal to the number K of the source user equipments, that is, when each relay user equipment cooperates with only one source user equipment for communication, Bit Error Rate (BER) performance is better.

Fig. 7 is a diagram illustrating BER performance comparison between a network coding cooperative communication mechanism (taking a scenario of 4source user equipments (4source user networks) as an example) and a Non-cooperative mechanism, which assumes 4source user equipments and 1relay user equipment, and a repetition code rate of 1/16, where a Conventional Non-cooperative communication interlace-co IDMA scheme in fig. 7 represents a Conventional Non-cooperative communication interlace multiple access mechanism; the cooperative Scheme represents a cooperative communication mechanism, the Iteration n represents n iterations, and n is 1, 2, 3, 4. The coding mechanism of the relay user equipment isAs can be seen from FIG. 7, if the BER is 2.6X 10^-3Then after 4 iterations, the communication mechanism under network coding Cooperation has cooperative Gain (cooperative Gain) of 8dbEb/N0 relative to the non-cooperative mechanism, and as can be seen from fig. 7, in the low Eb/N0 region, the Gain of BER performance can be ignored. Since in this slice area the soft information obtained by the network encoder is low. In the higher Eb/N0 region, there is a higher gain in BER performance as Eb/N0 increases because in this slice region the soft information gives the network a more accurate value for decoding, and thus a significant diversity gain is achieved.

Fig. 8 shows a performance diagram of a network coding cooperative communication mechanism based on different numbers of Source ues (taking a scenario (1Relay User hierarchy) of 1Relay ue as an example), where Non-cooperative IDMA scheme (4Source Users) in fig. 8 represents a Non-cooperative communication interleaved multiple access mechanism of 4Source ues; the collaboration Scheme (k Source Users) represents a cooperative communication mechanism of k Source user equipments. Assuming source user equipment numberWith the target K being 4, 6, 8, 1relay user equipment and the repetition code rate being 1/16, it can be seen from fig. 8 that the BER performance of the network coding cooperative transmission mechanism is decreasing with the increase of the source user equipment. Because the relay user equipment needs to perform the xor merging operation on the data of the source user equipment:j-1, …, (N-K), combined together and transmitted forward again, the more the combined signal, the less user cooperative diversity obtained, the higher the BER.

Fig. 9 is a schematic diagram illustrating the performance impact of the adaptive multi-Source multi-User transmission method on a network coding cooperative communication mechanism (taking a scenario of 4Source User devices (4Source User hierarchy) as an example), where a conditional Non-co IDMA scheme in fig. 9 represents a Conventional Non-cooperative communication interleaved multiple access mechanism; the cooperative communication Scheme is expressed as a cooperative communication mechanism, and the Adaptive cooperative communication Scheme is expressed as an Adaptive cooperative communication mechanism; assuming that the number of source ues is 4, 2 relay ues, and the repetition code rate is 1/16, the network coding mechanism performs network coding transmission on all recovered information bit sequences of the source ues for one relay ue, and it operates as:the other relay does not decode, but directly forwards the broadcast data received in the first time slot in the third time slot. As can be seen from fig. 9, in the case of improving the system throughput, although another directly forwarded relay user equipment alone occupies one more time slot, in this adaptive relay transmission scenario, the BER performance of the system is still improved to some extent, especially in the case of high channel signal-to-noise ratio.

Referring to fig. 10, an embodiment of the present invention provides a communication device, which may be a base station, including:

a data receiving unit 10, configured to receive a modulated signal sent by a source user equipment in a first time slot, and receive the modulated signal sent by the source user equipment and a modulated signal sent by a relay user equipment in a second time slot; the modulation signal sent by the relay user equipment is a modulation signal obtained by recovering an information bit sequence of the source user equipment from the modulation signal sent by the source user equipment in a first time slot, carrying out network coding according to the recovered information bit sequence and modulating data obtained after the network coding;

a decoding unit 20, configured to obtain, by using the modulation signal received by the receiving unit in the first time slot and the modulation signal received in the second time slot, an information bit sequence of the modulation signal sent by the source user equipment before modulation.

Wherein, if the influence of the wireless channel on the modulated signals transmitted by the source user equipment and the relay user equipment is considered, the data receiving unit 10 is used for receiving a first distorted signal from the source user equipment in a first time slot; receiving a second distorted signal from the source user equipment and a distorted signal from the relay user equipment at a second time slot; the first distortion signal and the second distortion signal are signals of the same modulation signal which is respectively sent by the source user equipment in a first time slot and a second time slot and is distorted in the transmission process; the distortion signal from the relay user equipment is a signal obtained after the modulation signal sent by the relay user equipment in the second time slot is distorted in the transmission process, wherein the modulation signal sent by the relay user equipment in the second time slot is a modulation signal obtained by recovering an information bit sequence of a source user equipment from the modulation signal sent by the source user equipment in the first time slot by the relay user equipment, performing network coding by using the recovered information bit sequence, and modulating data obtained after the network coding; the decoding unit 20 is configured to obtain an information bit sequence of the modulated signal sent by the source user equipment before modulation by using the distorted signal received in the first time slot and the distorted signal received in the second time slot.

Wherein, the decoding unit 20 includes:

referring to fig. 11, the decoding unit 20 includes:

a multi-user detection unit 21, configured to obtain an external log-likelihood ratio corresponding to a modulation signal sent by an ith source user equipment in a first time slot, an external log-likelihood ratio corresponding to a modulation signal sent by an ith source user equipment in a second time slot, and an external log-likelihood ratio corresponding to a modulation signal sent by multiple relay user equipments in communication with the ith source user equipment in cooperation with the second time slot; specifically, the multiuser detecting unit 21 includes: the first multi-user detection unit is used for obtaining an external log-likelihood ratio corresponding to a modulation signal sent by the ith source user equipment of the first time slot by using an external log-likelihood ratio calculation formula; the second multi-user detection unit is used for obtaining an external log-likelihood ratio corresponding to a modulation signal sent by the ith source user equipment of the second time slot by using an external log-likelihood ratio calculation formula; the third multi-user detection unit is used for obtaining external log-likelihood ratios corresponding to modulation signals sent by a plurality of relay user equipment which are communicated by the ith source user equipment and are cooperated by the second time slot;

a deinterleaving unit 22, configured to deinterleave an external log-likelihood ratio corresponding to a modulation signal sent by an ith source user equipment in the first time slot; de-interleaving external log-likelihood ratios corresponding to modulation signals sent by ith source user equipment in a second time slot; de-interleaving external log-likelihood ratios corresponding to modulation signals sent by the plurality of relay user equipment in a second time slot; specifically, the deinterleaving unit 22 includes: the first deinterleaving unit is used for deinterleaving an external log-likelihood ratio corresponding to a modulation signal sent by the ith source user equipment in the first time slot; the second deinterleaving unit is used for deinterleaving the external log-likelihood ratio corresponding to the modulation signal sent by the ith source user equipment in the second time slot; and a third deinterleaving unit, configured to deinterleave external log-likelihood ratios corresponding to modulation signals sent by the plurality of relay user equipments in the second time slot;

a first network coding and decoding unit 23, configured to perform network decoding on a deinterleaved signal with an external log-likelihood ratio corresponding to a modulation signal sent by an ith source user equipment in a first time slot and a deinterleaved signal with an external log-likelihood ratio corresponding to a modulation signal sent by a plurality of relay user equipments in cooperation with the ith source user equipment in a second time slot to obtain a first network decoding result;

specifically, the first network coding and decoding unit is specifically configured to obtain a sum of first type contributions, to the ith source user equipment, of each relay user equipment that cooperates with the ith source user equipment for communication; wherein, the first contribution of the relay user equipment cooperating with the ith source user equipment to the ith source user equipment in the first time slot is obtained by using the following formula:

A second network coding and decoding unit 24, configured to perform network decoding on the deinterleaved signals with the external log-likelihood ratios corresponding to the modulated signals sent by the ith source ue in the second time slot and the deinterleaved signals with the external log-likelihood ratios corresponding to the modulated signals sent by the multiple relay ues in the second time slot in cooperation with the ith source ue to communicate, so as to obtain a second network decoding result;

specifically, the second network coding and decoding unit is specifically configured to obtain a second network decoding result, and includes: acquiring the sum of second contributions of each relay user equipment for cooperating the communication of the ith source user equipment to the ith source user equipment; wherein the second type of contribution of the relay user equipment cooperating with the ith source user equipment to the ith source user equipment in the second time slot is obtained by using the following formula:

A summation unit 25, configured to calculate a sum of a signal obtained by deinterleaving an external log-likelihood ratio corresponding to a modulation signal sent by an ith source user equipment in a first time slot, a signal obtained by deinterleaving an external log-likelihood ratio corresponding to a modulation signal sent by an ith source user equipment in a second time slot, a first network decoding result, and a second network decoding result;

a channel decoding unit 26, configured to perform channel decoding on the sum calculated by the summing unit to obtain a first channel decoding result; performing channel decoding on a signal subjected to external log-likelihood ratio de-interleaving corresponding to a modulation signal sent by ith source user equipment in a second time slot to obtain a second channel decoding result; performing channel decoding on a signal subjected to de-interleaving by an external log-likelihood ratio value corresponding to a modulation signal sent by relay user equipment for communication of the ith source user equipment in cooperation with a second time slot to obtain a third channel decoding result; specifically, the channel decoding unit includes: the first channel decoding unit is used for carrying out channel decoding on the sum calculated by the summation unit to obtain a first channel decoding result; a second channel decoding unit, configured to perform channel decoding on a signal, which is obtained after deinterleaving an external log-likelihood ratio corresponding to a modulation signal sent by an ith source user equipment in a second time slot, to obtain a second channel decoding result; and a third channel decoding unit, configured to perform channel decoding on a signal, which is obtained after deinterleaving an external log-likelihood ratio corresponding to a modulation signal sent by a relay user equipment in which the second time slot cooperates with the ith source user equipment for communication, to obtain a third channel decoding result.

An interleaving unit 27, configured to interleave the first channel decoding result with a difference value of a signal after deinterleaving an external log-likelihood ratio corresponding to a modulation signal sent by an ith source user equipment in the first time slot, to obtain a first interleaving result; interleaving the second channel decoding result with a difference value of a signal after de-interleaving of an external log-likelihood ratio value corresponding to a modulation signal sent by ith source user equipment of a second time slot to obtain a second interleaving result; interleaving a third channel decoding result with a difference value of a signal after de-interleaving of an external log-likelihood ratio corresponding to a modulation signal sent by the relay user equipment in a second time slot to obtain a third interleaving result; and feeding back a first interleaving result, a second interleaving result and a third interleaving result to the multi-user detection unit, so that the multi-user detection unit substitutes the first interleaving result into an external log-likelihood ratio calculation formula corresponding to a modulation signal sent by the ith source user equipment in the first time slot, substitutes the second interleaving result into an external log-likelihood ratio calculation formula corresponding to a modulation signal sent by the ith source user equipment in the second time slot, and substitutes the third interleaving result into an external log-likelihood ratio calculation formula corresponding to a modulation signal sent by the relay user equipment in the second time slot. Specifically, the interleaving unit includes: the first interleaving unit is used for interleaving the first channel decoding result with the difference value of the signal after the de-interleaving of the external log-likelihood ratio value corresponding to the modulation signal sent by the ith source user equipment in the first time slot to obtain a first interleaving result and feed the first interleaving result back to the first multi-user detection unit; a second interleaving unit, configured to interleave the second channel decoding result with a difference between external log-likelihood ratio de-interleaved signals corresponding to modulation signals sent by the ith source user equipment in the second time slot, to obtain a second interleaving result, and feed the second interleaving result back to the second multi-user detection unit; and a third interleaving unit, configured to interleave the third channel decoding result with a difference between the external log-likelihood ratio deinterleaved signals corresponding to the modulation signals sent by the relay user equipment in the second time slot, to obtain a third interleaving result, and feed the third interleaving result back to the third multi-user detection unit.

In order to implement the adaptive multi-source multi-relay cooperative communication mechanism, the communication device further comprises:

a determining unit 30, configured to determine, according to the obtained information bit sequence before modulation by the source user equipment, whether a reception error rate of the communication device is smaller than a predetermined error rate, or whether a system capacity reaches a predetermined numerical value;

a signaling sending unit 40, configured to send, to a non-relay user equipment in a current system, indication information indicating that the non-relay user equipment is used as a new relay user equipment when a reception error rate of the communication equipment is less than a predetermined error rate or a system capacity reaches a predetermined value.

The base station further comprises:

a signaling receiving unit 50, configured to receive a reception error rate of the new relay user equipment sent by the new relay user equipment;

a determining unit 60, configured to determine, according to the reception error rate of the new relay user equipment, the number of source user equipments with which the relay user equipment cooperates; wherein the reception error rate of the new relay user equipment is sent after the new relay user equipment determines that the own reception error rate reaches a predetermined requirement;

the signaling sending unit 30 is further configured to send, to the new relay user equipment, indication information indicating the number of source user equipments with which the new relay user equipment cooperates.

The communication equipment of the embodiment of the invention receives the modulation signal sent by the source user equipment in the first time slot, receives the modulation signal sent by the source user equipment and the modulation signal sent by the relay user equipment in the second time slot, and can acquire the information bit sequence before the modulation of the source user equipment by utilizing the signals received by the two time slots, thereby saving the data transmission time; meanwhile, the sensitivity of the system can be improved by a multi-relay cooperative transmission mode, and higher diversity gain can be obtained; further, relay transmission can be completed for a plurality of source user equipments under the condition of only one relay user equipment, and obvious error rate improvement is obtained.

An embodiment of the present invention provides a network system, including: the communication device, the source user equipment and the plurality of relay user equipments described above, wherein,

the relay user equipment is used for recovering an information bit sequence of the source user equipment from a modulation signal sent by the source user equipment in a first time slot, performing network coding by using the recovered information bit sequence, modulating the coded data, and sending the modulation signal obtained by modulation in a second time slot.

In order to realize a self-adaptive multi-source multi-user communication mechanism, the communication equipment is also used for judging whether the receiving performance of the base station reaches a preset condition according to the obtained information bit sequence before the modulation of the source user equipment, and if so, sending indication information for indicating the non-relay user equipment as new relay user equipment to the non-relay user equipment in the current system;

the new relay user equipment is used for judging whether the receiving error rate of the new relay user equipment reaches a threshold value, if so, recovering an information bit sequence of the source user equipment from a modulation signal sent by the source user equipment in a first time slot, carrying out network coding by using the recovered information bit sequence, modulating the coded data, and sending a modulation signal obtained by modulation in a second time slot; if not, the source user equipment forwards the modulation signal transmitted in the first time slot to the base station in the third time slot. Wherein the third time slot is a separate time slot after the second time slot.

It will be understood by those skilled in the art that all or part of the steps in the method for implementing the above embodiments may be implemented by hardware that is instructed to implement by a program, and the program may be stored in a computer-readable storage medium, such as a read-only memory, a magnetic or optical disk, and the like.

The multi-source multi-relay cooperative communication method, the communication device and the network system provided by the embodiment of the invention are described in detail, a specific embodiment is applied in the description to explain the principle and the implementation mode of the invention, and the description of the embodiment is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present invention.

Claims

1. A multi-source multi-relay cooperative communication method is characterized by comprising the following steps:

the communication equipment acquires an information bit sequence of the modulation signal sent by the source user equipment before modulation by using the modulation signal received at the first time slot and the modulation signal received at the second time slot;

the communication device acquires the information bit sequence of the modulation signal sent by the source user equipment before modulation by using the signal received in the first time slot and the signal received in the second time slot, and the information bit sequence comprises:

A. the communication equipment obtains a de-interleaved signal of an external log-likelihood ratio corresponding to a modulation signal sent by ith source user equipment of a first time slot, a de-interleaved signal of an external log-likelihood ratio corresponding to a modulation signal sent by ith source user equipment of a second time slot and a de-interleaved signal of an external log-likelihood ratio corresponding to a modulation signal sent by a plurality of relay user equipment which is communicated with ith source user equipment and is cooperated with the ith source user equipment of the second time slot;

B. the communication equipment performs network decoding on a signal subjected to de-interleaving by using an external log-likelihood ratio corresponding to a modulation signal sent by ith source user equipment in a first time slot and a signal subjected to de-interleaving by using an external log-likelihood ratio corresponding to a modulation signal sent by a plurality of relay user equipment in cooperation with the ith source user equipment in a second time slot to obtain a first network decoding result; network decoding is carried out on a signal subjected to de-interleaving by utilizing the external log-likelihood ratio corresponding to the modulation signal sent by the ith source user equipment in the second time slot and a signal subjected to de-interleaving by utilizing the external log-likelihood ratio corresponding to the modulation signal sent by a plurality of relay user equipment which is communicated by the ith source user equipment in cooperation with the second time slot, so as to obtain a second network decoding result;

C. the communication equipment calculates the sum of the de-interleaved signal of the external log-likelihood ratio corresponding to the modulated signal sent by the ith source user equipment of the first time slot, the de-interleaved signal of the external log-likelihood ratio corresponding to the modulated signal sent by the ith source user equipment of the second time slot, the first network decoding result and the second network decoding result, and performs channel decoding on the sum to obtain a first channel decoding result.

2. The method of claim 1,

obtaining the first network decoding result comprises:

acquiring the sum of first type contributions of each relay user equipment for cooperating the communication of the ith source user equipment to the ith source user equipment;

wherein, the first contribution of the relay user equipment cooperating with the ith source user equipment to the ith source user equipment in the first time slot is obtained by using the following formula:

3. The method of claim 1,

obtaining the second network decoding result comprises:

acquiring the sum of second contributions of each relay user equipment for cooperating the communication of the ith source user equipment to the ith source user equipment;

wherein the second type of contribution of the relay user equipment cooperating with the ith source user equipment to the ith source user equipment in the second time slot is obtained by using the following formula:

4. The method of claim 1, further comprising:

D. the communication equipment interweaves the first channel decoding result and the difference value of the signal after the de-interweaving of the external log likelihood ratio value corresponding to the modulation signal sent by the ith source user equipment of the first time slot to obtain a first interweaving result, and substitutes the first interweaving result into the external log likelihood ratio value calculation formula corresponding to the modulation signal sent by the ith source user equipment of the first time slot; decoding the signal after deinterleaving the external log-likelihood ratio value corresponding to the modulation signal sent by the ith source user equipment in the second time slot to obtain a second channel decoding result; interleaving the second channel decoding result with a difference value of a signal after de-interleaving of an external log-likelihood ratio corresponding to a modulation signal sent by ith source user equipment in a second time slot to obtain a second interleaving result, and substituting the second interleaving result into an external log-likelihood ratio calculation formula corresponding to the modulation signal sent by the ith source user equipment in the second time slot; and performing channel decoding on a signal subjected to de-interleaving by an external log-likelihood ratio corresponding to a modulation signal sent by relay user equipment for the communication of the ith source user equipment in cooperation with the second time slot to obtain a third channel decoding result, interleaving the third channel decoding result with a difference value of the signal subjected to de-interleaving by the external log-likelihood ratio corresponding to the modulation signal sent by the relay user equipment in the second time slot to obtain a third interleaving result, substituting the third interleaving result into an external log-likelihood ratio operation formula corresponding to the modulation signal sent by the relay user equipment in the second time slot, and returning to the step A, B, C until an iteration termination condition is met.

5. The method of claim 1, further comprising:

when the communication equipment judges that the receiving error rate of the communication equipment is smaller than the preset error rate according to the obtained information bit sequence before the modulation of the source user equipment, and when the number of the relay user equipment in the cooperative communication system is smaller than that of the source user equipment, the communication equipment sends indication information indicating that the non-relay user equipment is used as new relay user equipment to the non-relay user equipment in the cooperative communication system;

or,

when the system capacity of the cooperative communication system reaches a preset value and the number of the relay user equipment in the cooperative communication system is smaller than that of the source user equipment, the communication equipment sends indication information indicating that the non-relay user equipment is used as new relay user equipment to the non-relay user equipment in the cooperative communication system.

6. The method of claim 5, further comprising:

the communication equipment receives the receiving error rate of the new relay user equipment sent by the new relay user equipment; determining the number of source user equipment cooperated by the new relay user equipment according to the receiving error rate of the new relay user equipment; wherein the reception error rate of the new relay user equipment is sent to the communication equipment when the reception error rate of the new relay user equipment is less than a threshold;

and the communication equipment sends indication information indicating the number of the user equipment of the cooperation source of the new relay user equipment to the new relay user equipment.

7. A communication device, comprising:

a decoding unit, configured to obtain an information bit sequence of the modulation signal sent by the source user equipment before modulation by using the modulation signal received by the receiving unit in the first time slot and the modulation signal received by the receiving unit in the second time slot;

wherein the decoding unit includes:

a multi-user detection unit, configured to obtain an external log-likelihood ratio corresponding to a modulation signal sent by an ith source user equipment in a first time slot, an external log-likelihood ratio corresponding to a modulation signal sent by an ith source user equipment in a second time slot, and an external log-likelihood ratio corresponding to a modulation signal sent by a plurality of relay user equipments in communication with the ith source user equipment in cooperation with the second time slot;

the deinterleaving unit is used for deinterleaving the external log-likelihood ratio value corresponding to the modulation signal sent by the ith source user equipment in the first time slot; de-interleaving external log-likelihood ratios corresponding to modulation signals sent by ith source user equipment in a second time slot; de-interleaving external log-likelihood ratios corresponding to modulation signals sent by the plurality of relay user equipment in a second time slot;

a first network coding and decoding unit, configured to perform network decoding on a deinterleaved signal with an external log-likelihood ratio corresponding to a modulation signal sent by an ith source user equipment in a first time slot and a deinterleaved signal with an external log-likelihood ratio corresponding to a modulation signal sent by a plurality of relay user equipments in cooperation with the ith source user equipment in a second time slot to obtain a first network decoding result;

a second network coding and decoding unit, configured to perform network decoding on a deinterleaved signal with an external log-likelihood ratio corresponding to a modulation signal sent by an ith source user equipment in a second time slot and a deinterleaved signal with an external log-likelihood ratio corresponding to a modulation signal sent by a plurality of relay user equipments in cooperation with the ith source user equipment in the second time slot to obtain a second network decoding result;

the summation unit is used for calculating the sum of a signal after de-interleaving by an external log-likelihood ratio corresponding to a modulation signal sent by the ith source user equipment of the first time slot, a signal after de-interleaving by an external log-likelihood ratio corresponding to a modulation signal sent by the ith source user equipment of the second time slot, a first network decoding result and a second network decoding result;

and the channel decoding unit is used for carrying out channel decoding on the sum calculated by the summation unit to obtain a first channel decoding result.

8. The communication device of claim 7,

a first network coding and decoding unit, configured to obtain a sum of first type contributions, to an ith source user equipment, of each relay user equipment that cooperates with the ith source user equipment for communication;

9. The communication device of claim 8,

a second network coding and decoding unit, configured to obtain a sum of second type contributions of relay user equipments cooperating with the ith source user equipment to the ith source user equipment;

10. The communication device of claim 8,

the channel decoding unit is also used for carrying out channel decoding on the signal after de-interleaving of the external log-likelihood ratio value corresponding to the modulation signal sent by the ith source user equipment in the second time slot to obtain a second channel decoding result; performing channel decoding on a signal subjected to de-interleaving by an external log-likelihood ratio value corresponding to a modulation signal sent by relay user equipment for communication of the ith source user equipment in cooperation with a second time slot to obtain a third channel decoding result;

the decoding unit further includes:

the interleaving unit is used for interleaving the first channel decoding result with a difference value of a signal after de-interleaving of an external log-likelihood ratio value corresponding to a modulation signal sent by ith source user equipment in the first time slot to obtain a first interleaving result; interleaving the second channel decoding result with a difference value of a signal after de-interleaving of an external log-likelihood ratio value corresponding to a modulation signal sent by ith source user equipment of a second time slot to obtain a second interleaving result; interleaving a third channel decoding result with a difference value of a signal after de-interleaving of an external log-likelihood ratio corresponding to a modulation signal sent by the relay user equipment in a second time slot to obtain a third interleaving result; and feeding back a first interleaving result, a second interleaving result and a third interleaving result to the multi-user detection unit, so that the multi-user detection unit substitutes the first interleaving result into an external log-likelihood ratio calculation formula corresponding to a modulation signal sent by the ith source user equipment in the first time slot, substitutes the second interleaving result into an external log-likelihood ratio calculation formula corresponding to a modulation signal sent by the ith source user equipment in the second time slot, and substitutes the third interleaving result into an external log-likelihood ratio calculation formula corresponding to a modulation signal sent by the relay user equipment in the second time slot.

11. The communication device of claim 7, further comprising:

the judging unit is used for judging whether the receiving error rate of the communication equipment is smaller than the preset error rate according to the obtained information bit sequence before the source user equipment is modulated; wherein the communication device is located in a cooperative communication system;

a signaling sending unit, configured to send, when the determination result of the determining unit is yes and the number of the relay user equipments in the cooperative communication system is smaller than the number of the source user equipment, indication information indicating that the non-relay user equipment is used as a new relay user equipment to the non-relay user equipment in the cooperative communication system;

or,

a judging unit configured to judge whether or not a system capacity of the cooperative communication system reaches a predetermined value;

and a signaling sending unit, configured to send, when the determination result of the determining unit is yes and the number of the relay user equipments in the cooperative communication system is smaller than the number of the source user equipment, indication information indicating that the non-relay user equipment is used as a new relay user equipment to the non-relay user equipment in the cooperative communication system.

12. The communication device of claim 11,

the communication device further includes:

a signaling receiving unit, configured to receive a reception error rate of the new relay user equipment sent by the new relay user equipment;

a determining unit, configured to determine, according to the reception error rate of the new relay user equipment, the number of source user equipments with which the relay user equipment cooperates; wherein the reception error rate of the new relay user equipment is sent to the communication equipment when the reception error rate of the new relay user equipment is less than a threshold;

the signaling sending unit is further configured to send, to the new relay user equipment, indication information indicating the number of source user equipments with which the new relay user equipment cooperates.

13. A cooperative communication system, comprising: the communication device, the source user device, and the plurality of relay user devices of any of claims 7-12,

14. The cooperative communication system as recited in claim 13,

the communication device is further configured to send indication information indicating that the non-relay user equipment serves as new relay user equipment to the non-relay user equipment in the cooperative communication system when the received bit error rate of the communication device is judged to be smaller than the predetermined bit error rate according to the obtained information bit sequence before modulation of the source user equipment and when the number of the relay user equipment in the cooperative communication system is smaller than the number of the source user equipment;

or,

the communication device is further configured to send, to a non-relay user device in the cooperative communication system, indication information indicating that the non-relay user device is a new relay user device when the system capacity of the cooperative communication system reaches a predetermined value and the number of relay user devices in the cooperative communication system is smaller than the number of source user devices.

15. The cooperative communication system as recited in claim 14, further comprising:

the new relay user equipment is used for judging whether the receiving error rate of the new relay user equipment reaches a threshold value, if so, recovering an information bit sequence of the source user equipment from a modulation signal sent by the source user equipment in a first time slot, carrying out network coding by using the recovered information bit sequence, modulating data obtained after the network coding, and sending a modulation signal obtained by modulation in a second time slot; and if not, transmitting the modulation signal transmitted by the source user equipment in the first time slot to the communication equipment in the third time slot.