CN101567761B - Interleaving iterative multi-user communication method based on the network coding cooperative relay - Google Patents

Abstract

The invention belongs to the wireless communication technology field, in particular relates to a double time slot interleaving iterative multi-user communication method based on the network coding cooperative relay. The method adopts a wireless relay system model, communication nodes are divided into a target user node, an interference user node, a relay node and a base station node; the relay node is provided with a baseband processing module, and carries out network coding to relay data; and in addition, a base station receiver utilizes the interleaving iterative interference elimination improvement algorithm of double time slot network coding to carry out the multi-user signal detection. The method can provide space diversity gain for the base station of a receiving terminal and reduce path loss, can realize higher transmission reliability compared with the traditional multi-user system, and synchronously can reduce the time of relay transmission and improve the system capacity.

Description

A kind of interleaving iterative multi-user communication method of coding cooperative relaying Network Based

Technical field

The invention belongs to wireless communication technology field, be specifically related to a kind of interleaving iterative multi-user communication method of coding cooperative relaying Network Based.

Background technology

In traditional wireline communication network, data adopt the mechanism of storage forwarding substantially when transmitting through router.Information through router node, is sent to destination node by source node.As a rule, the intermediate node of network does not carry out any flow chart of data processing.

Along with the fast development of multimedia service, large capacity documents transmission is used more and more extensive.Increasing network throughput, reduce transmission error rates, reduce the network energy resource consumption, is the emphasis of communication networks nowadays network development, and network code (network coding) theory produces thus.The central idea of network code theory is by router data to be carried out certain processing, and simple XOR uniform enconding for example reaches the theoretical upper limit of max-flow min-cut thus.In view of this excellent characteristics of network code, this technology more and more receives the concern of industrial quarters and academia.

Allowing the intermediate node router that the transmission of data is carried out network code increases power system capacity, reduces transmission delay, and this has obtained confirmation in wire net.Research and the application of network code in radio communication also is in the starting stage.In fact, because the broadcast characteristic of Radio Link, wireless transmission can provide for the utilization of network code good application scenarios.The design of coding Network Based can solve more insurmountable technical problems in traditional multi-user communication, network route, the protocol layer design, can improve the overall performance of wireless communication system.

Cooperating relay (Cooperative Relay) is a kind of brand-new diversity technique.Along with the fast development of radio multimedium business, the user is more and more higher to the requirement of data communication capacity and transmission quality.In order to reduce path loss and to realize the full diversity transmission gain, people have proposed the collaboration communication method based on relaying.This communication means can be divided into the amplification forwarding non-regenerative relaying, and regenerative repeating etc. is transmitted in decoding.The advantage of cooperating relay is to expand the coverage area, to increase the capacity of wireless communication link, reduction transmission error rates.The cooperating relay technology can be used in the multiple systems such as rear 3G/4G cellular radio communication network, wireless MAN, WLAN (wireless local area network) and wireless sensor network.In recent years, international numerous manufacturers and research and development institution are stepping up the cooperating relay communication equipment of development of new, and formulate corresponding technical specification.Try hard to exploitation by relay station of new generation, build up this to reduce communication network cloth, increase the reliability of transfer of data, and promote network coverage ability and operating benefit.

Uplink multi-users communication belongs to how point-to-point communication pattern.In the multi-user communication situation, will run into the situations such as the new problem, the particularly mutual interference of multiple user signals phase that does not have in the point-to-point communication of many alone families, mutual stack.The solution of tradition multi-user communication has three kinds usually: time division multiple access (TDMA, Time Division Multiple Access) mode, frequency division multiple access (FDMA, Frequency Division Multiple Access) mode and code division multiple access (CDMA, Code DivisionMultiple Access).The time division multiple access trunking scheme will be divided into continuous transmission time slot the time exactly, and distribute to a plurality of users, mutually collide interference problem with this nothing that realizes that data transmit between a plurality of users.The system control information of the method is simply ripe, but it is had relatively high expectations synchronously to system time.FDMA by whole frequency spectrum is divided into separate frequency band, is assigned to a plurality of users exactly, reaches the purpose of avoiding mutual interference.The method is loose to the management expectancy of time synchronized, but strict to the designing requirement of radio-frequency filter.From the angle of information theory power system capacity, this time-division multiple access and frequency division multiple access dual mode are equivalent.Code division multiple access then is to realize multi-user communication to the different orthogonal code of each user assignment.Iterative detection is a basic theory branch of message area, suitable development and application have been obtained for many years, professor C.Berrou such as French Britain university has proposed Turbo Code channel decoding, the Turbo channel equalization of the scholar's research such as the M.Sandell of Sydney University, Australia and R.Yan, minute multiple access multiuser detection that interweaves that Li professor Ping of City University of Hong Kong proposes, etc.In recent years, in a lot of emerging communication technical fields (such as cooperating relay communication), how to further develop the just direction of numerous scientific research institutions effort of Turbo iterative detection technology.

Present multi-user communication stresses in TDMA, FDMA, cdma communication system more.Then just begin for the design based on the interleaving iterative multi-user communication system of relay cooperative.

Summary of the invention

The object of the invention is the facing multiple users system, proposes a kind of interleaving iterative multi-user communication method that can reduce transmission error rates, raising transmission rate, expand the coding relay cooperative Network Based of coverage that has.

The interleaving iterative multi-user communication method of the coding relay cooperative Network Based that the present invention proposes comprises the relay transmission method that adopts linear network encoding, and two time slot network coding interleaving iteratives of receiving terminal detect communication means.In the network code interleaving iterative communication means research work in the past of two time slot cooperating relay, also do not occur.Experimental results show that the method can offer the system space diversity, can strengthen the throughput of system, and reduce the relay transmission time.

The system model of the interleaving iterative multi-user communication method of coding relay cooperative Network Based of the present invention as shown in Figure 1.In this system model, targeted customer's source node, interference user source node, via node and base station are arranged.Via node has baseband processing module, thereby can realize baseband signal decoding processing.Via node is equipped with different base band pseudo random interleavers, and its interlacing pattern design can be adopted the methods such as the diagonal angle interweaves, block interleaving, also can select the Turbo code inner interleaver method for designing in the 3G (Third Generation) Moblie agreement.

The working mechanism of the interleaving iterative multi-user communication method of coding relay cooperative Network Based is to produce different interlacing patterns by pseudo random interleaver, is dispensed to each user.The mutual interference that via node utilizes the interleaving iterative interference cancellation techniques to carry out between multiple user signals is eliminated, and then transmits by linear network encoding.At receiving terminal, the base station utilizes two time slot network coding interleaving iterative technology for detection to go out targeted customer's signal.The whole trunking traffic flow process of the present invention design is divided into two time slot stages carries out, and scheme is referring to Fig. 1.

(1) first time slot multi-user carries out up broadcasting transmitting

In first time slot, all users carry out up broadcast communication.Be specially: in the 1st relaying stage, the data of targeted customer, interference user interweave through interleaver, carry out data broadcast and propagate, and will be received by via node and base station, as shown in Figure 1.Via node and base station receiver have received the interference signal of targeted customer's useful signal He other interference users.Then, the via node receiving element will carry out the base band signal process such as iterative interference cancellation and decoding.

The baseband processing module of via node as shown in Figure 2.This module is comprised of reception ﹠ disposal unit and emission processing unit.The radio-frequency module of reception ﹠ disposal unit receives wireless signal, and carries out intermediate frequency process, physical layer iterative interference cancellation, Fu Haoxieyingshe and decipher judgement, and is sent to the media Access Layer and stores;

(2) second time slot via node the transmission of datas, base station carry out multi-user data and detect

In the second slot transmission, the via node transmitter unit carries out linear network encoding, chnnel coding and sign map with the data that the media Access Layer is stored, finally by be emitted to the base station receiving terminal by intermediate frequency/RF processing unit.At receiving terminal, the base station utilizes comprehensive two signals that time slot is received two time slot network coding iterative interference cancellation methods carry out target user data and detects.Corresponding network code relaying interleaving iterative disturbs the improvement elimination algorithm to see appendix 1.

Advantage of the present invention

(1) transmits by the network code signal based on via node, can reduce path loss for the receiving terminal base station.Thus, will make the base station under low received signal to noise ratio condition, reduce transmission error rates.

The linear network encoding signal that the via node in (2) second moment is transmitted can provide space diversity gain for the receiving terminal base station.Thus, the transmission accuracy of system will be significantly improved.

Description of drawings

Fig. 1 is the wireless cooperative relay network system.

Fig. 2 is the signal processing flow block diagram of via node.

Fig. 3 is the interleaving iterative multi-user base station receiver device design frame chart of coding relaying Network Based.

Fig. 4 is that conclusion one is analyzed in system emulation of the present invention.

Fig. 5 is that conclusion two is analyzed in system emulation of the present invention.

Embodiment

The interleaving iterative multi-user base station received communication method of the coding relaying Network Based that the present invention is proposed, its implementation step is as follows:

1, data are the random data of Gaussian distributed.

2, produce one group of pseudo random interleaving pattern, and be assigned in each user interleaver.Simultaneously, via node and base station receiver are also stored this group interlacing pattern.

3, system divides two time slots to carry out work:

The emission of (1) first time slot is processed

In the first time slot, the media Access Layer of targeted customer and interference user is all set certain transmitting power to the data that will transmit, and data are delivered to the physical layer transmitter module; In the physical layer transmitter module, data will at first be carried out chnnel coding (as: duplication code coding), carry out Bit Interleave according to interlacing pattern again, then carry out the symbol constellation modulation, then carry out the digital filtering of intermediate frequency; According to the corresponding power emission factor, by omnidirectional antenna data transmission is gone out again;

(2) first time slot reception ﹠ disposals

In the first working time slot, the receiver module of via node part will be carried out iterative receiver decoding.Handling process is: the radio-frequency module of receiver receives wireless signal, and this receives signal and comprises interference signal and useful signal; Receiver module carries out corresponding intermediate frequency process to received signal, according to the interlacing pattern that distributes, carries out the iterative interference cancellation of data and processes.Then, symbol de-maps, channel decoding obtain the log-likelihood value of signal.And, will decipher the data obtained and be input to the media Access Layer, carry out the storage of verification and data, in order to next slot transmission;

In the first working time slot, base station receiver also will obtain the weak multi-user reception signal of signal energy.At this moment, base station receiver is stored these signals.Simultaneously, wait for the network code repeating signal that via node transmits.

The emission of (3) second time slots is processed

In the second time slot emission process, the transmitting power that the media Access Layer of via node is certain with the data setting of storing, and data are delivered to the physical layer transmitter module; Carry out again two network codes between the user, then duplication code coding, symbol constellation modulation; Then Digital IF Processing is crossed omni-directional antenna transmission according to repeat transmitted power with data communication device again and is gone out;

(4) second time slot reception ﹠ disposals

In the second time slot receiving course, the receiver module of receiving terminal base station part will be carried out iterative processing, and handling process is: the radio-frequency module of receiver receives signal, and carries out to received signal corresponding intermediate frequency process; Then, carry out the iterative interference cancellation of the coding Network Based of data according to the interlacing pattern that distributes and process, referring to Fig. 3.Specific algorithm sees below.

Fig. 4, Fig. 5 are last simulation result, wherein:

Fig. 4 shows, compares with traditional interleaved multi-user iteration communication means, and the interleaving iterative multi-user communication method of two time slots coding cooperative relaying Network Based that the present invention proposes can significantly reduce the error rate.For example: take 2 targeted customers as example, four iteration, 1/4 code check duplication code is example: when the error rate is 2 * 10 ^-4Be example, the inventive method can be for the received signal to noise ratio performance gain of 2.5dB.

Fig. 5 shows, after iterations reduced, the multi-user communication method of the coding cooperative relaying Network Based that the present invention proposes still can significantly reduce the error rate, and obtains higher received signal to noise ratio performance gain.For example: take 2 targeted customers as example, second iteration, 1/4 code check duplication code is example: when the error rate is 2 * 10 ^-3Be example, the inventive method can be for the received signal to noise ratio performance gain of 3.6dB.

Among the present invention, it is as follows that the interleaving iterative of two time slot coding relayings Network Based disturbs elimination improvement algorithm in the system:

(1) calculate the junction network coding transmission to the signal log-likelihood value of base station:

$L\left(b_{\mathrm{RD}}\left(n\right)\right)=\frac{2R_{\mathrm{RD}}\left(n\right)}{{\mathrm{\σ}}^2},---(A-1)$

(2) calculate the coding repeating signal log-likelihood value Network Based that the targeted customer obtains:

$L_{\mathrm{RD}}\left(b_1\left(n\right)\right)=\log \frac{\exp \left(L\left(b_{\mathrm{RD}}\left(n\right)\right)\right)+\exp \left(L\left(b_2\left(n\right)\right)\right)}{1+\exp (L\left(b_{\mathrm{RD}}\left(n\right)\right)+L\left(b_2\left(n\right)\right))},---(A-2)$

(3) iteration initialization:

If L _a(x ₁(n))=0, (A-3)

(4) iterative process:

$E\left(x_1\left(n\right)\right)\⇐\tanh (L_a\left(x_1\left(n\right)\right)/2),---(A-4)$

$\mathrm{Var}\left(x_1\left(n\right)\right)\⇐1-E{\left(x_1\left(n\right)\right)}^2,---(A-5)$

$E\left({\mathrm{\ζ}}_1\left(n\right)\right)\⇐\underset{k\≠4}{\mathrm{\Σ}}E\left(x_k\left(n\right)\right),---(A-6)$

$\mathrm{Var}\left({\mathrm{\ζ}}_1\left(n\right)\right)\⇐\underset{k\≠1}{\mathrm{\Σ}}{\left|h_k\right|}^2\mathrm{Var}\left(x_k\left(n\right)\right)+{\mathrm{\σ}}^2,---(A-7)$

$L_a\left(x_1\left(n\right)\right)=\frac{2h_1\left(n\right)}{\mathrm{Var}\left({\mathrm{\ζ}}_1\left(n\right)\right)}(R_{\mathrm{RD}}\left(n\right)-E\left({\mathrm{\ζ}}_1\left(n\right)\right)),---(A-8)$

Here:

$R_{\mathrm{SD}}\left(n\right)=\underset{k=1}{\overset{K}{\mathrm{\Σ}}}{h}_k\left(n\right)x_k\left(n\right)+{\mathrm{\σ}}^2.---(A-9)$

Then, with L _a(x ₁(n)) deinterleaving, solution spread spectrum, again substitution posterior probability (APP:APosteriori Probability) channel decoder is deciphered, and obtains log-likelihood value L _e(b ₁(n)).

(5) network code log-likelihood value stack

${\tilde{L}}_e\left(b_1\left(n\right)\right)=L_{\mathrm{RD}}\left(b_1\left(n\right)\right)+L_e\left(b_1\left(n\right)\right)---(A-10)$

Again with spread spectrum as a result, interweaving obtains L _a(x ₁(n)), (A-2) formula of bringing into is again carried out next iteration.

Symbol description:

R _RD(n): via node is to the reception signal of base station, R _SD(n): the source is to the reception signal of base station, b _RD(n) be the junction network code signal, b ₁(n) be targeted customer 1 data, b ₂(n) be targeted customer 2 data, tanh (): hyperbolic tangent function, E (x (n)): about the expectation of variable x (n), Var (x (n)): about the variance of variable x (n), ζ ₁(n): interference signal, for user 1, Customs Assigned Number changes, and its corresponding subscript also changes difference, E (ζ ₁(n)): interference signal average, Var (ζ ₁(n)): interference signal variance, L _a(x ₁(n)): user 1 modulation symbol x ₁(n) log-likelihood value, L _e(b ₁(n)): the log-likelihood value behind targeted customer's 1 data decoding,

The log-likelihood value of targeted customer's 1 data after relay reception upgrades, h _k(n): k user's channel fading value, σ ²: noise variance.

Claims (2)

1. the interleaving iterative multi-user communication method of two time slot coding cooperative relayings Network Based is characterized in that adopting the wireless relay system model, and wherein, communication node is divided into targeted customer's node, interference user node, via node and base-station node; Via node has baseband processing module, and has different base band pseudo random interleavers, and its interlacing pattern of this pseudo random interleaver adopts that diagonal angle interweaves, block interleaving or the inner interleaving design method of Turbo code; Produce different interlacing patterns by pseudo random interleaver, distribute to targeted customer's node, interference user node, via node and base-station node; The interleaving iterative of the two time slot codings Network Based of base-station node utilization disturbs eliminates the mutual interference that improves between algorithm elimination multiple user signals, detects and obtains targeted customer's node data; Whole trunking traffic flow process is divided into two time slot stages, and is specific as follows:

The emission of (1) first time slot is processed

In the first time slot, the media Access Layer of targeted customer's node and interference user node is all set certain transmitting power to the data that will transmit, and data are delivered to the physical layer transmitter module; In the physical layer transmitter module, data will at first be carried out chnnel coding, carry out Bit Interleave according to interlacing pattern again, then carry out the symbol constellation modulation, then carry out the digital filtering of intermediate frequency; According to the corresponding power emission factor, by omnidirectional antenna data transmission is gone out again;

(2) first time slot reception ﹠ disposals

In the first time slot, the receiver module of via node part will be carried out iterative receiver decoding; Handling process is: the radio-frequency module of the receiver module of via node receives wireless signal, and this receives signal and comprises interference signal and useful signal; Receiver module carries out corresponding intermediate frequency process to received signal, according to the interlacing pattern that distributes, carries out the iterative interference cancellation of data and processes; Then, symbol de-maps, channel decoding obtain the log-likelihood value of signal; And, will decipher the data obtained and be input to the media Access Layer, carry out the storage of verification and data, in order to next slot transmission;

In the first time slot, the base-station node receiver also will obtain the weak multi-user reception signal of signal energy; At this moment, the base-station node receiver is stored these signals; Simultaneously, wait for the network code repeating signal that via node transmits;

The emission of (3) second time slots is processed

In the second time slot emission process, the transmitting power that the media Access Layer of via node is certain with the data setting of storing, and data are delivered to the physical layer transmitter module; Carry out again two network codes between the user node, then duplication code coding, symbol constellation modulation; Then Digital IF Processing is crossed omni-directional antenna transmission according to repeat transmitted power with data communication device again and is gone out;

(4) second time slot reception ﹠ disposals

In the second time slot receiving course, the receiver module of receiving terminal base-station node part will be carried out iterative processing, and handling process is: the radio-frequency module of the receiver module of base-station node receives signal, and carries out to received signal corresponding intermediate frequency process; Then, according to the interlacing pattern that distributes, utilize the interleaving iterative of two time slot codings Network Based to disturb to eliminate to data and improve algorithm process, the steps include:

(1) calculate the junction network coding transmission to the signal log-likelihood value of base station:

$L\left(b_{\mathrm{RD}}\left(n\right)\right)=\frac{{2R}_{\mathrm{RD}}\left(n\right)}{{\mathrm{\σ}}^2},---(A-1)$

(2) calculate the signal likelihood value that encoding user Network Based obtains:

$L_{\mathrm{RD}}\left(b_1\left(n\right)\right)=\log \frac{\exp \left(L\left(b_{\mathrm{RD}}\left(n\right)\right)\right)+\exp \left(L\left(b_2\left(n\right)\right)\right)}{1+\exp \left(L\left(b_{\mathrm{RD}}\left(n\right)\right)\right)+L\left(b_2\left(n\right)\right)},---(A-2)$

(3) iteration initialization:

If L _a(x ₁(n))=0, (A-3)

(4) iterative process:

$E\left(x_1\left(n\right)\right)\⇐\left(L_a(x_1\left(n\right)/2)\right),---(A-4)$

$\mathrm{Var}\left(x_1\left(n\right)\right)\⇐1-E{\left(x_i\left(n\right)\right)}^2,---(A-5)$

$E\left({\mathrm{\ζ}}_1\left(n\right)\right)\⇐\underset{k\≠1}{\mathrm{\Σ}}E\left(x_k\left(n\right)\right),---(A-6)$

$\mathrm{Var}\left({\mathrm{\ζ}}_1\left(n\right)\right)\⇐\underset{k\≠1}{\mathrm{\Σ}}{\left|h_k\right|}^2\mathrm{Var}{\left(x_k\left(n\right)\right)+\mathrm{\σ}}^2,---(A-7)$

$L_a\left(x_1\left(n\right)\right)=\frac{{2h}_1\left(n\right)}{\mathrm{Var}\left({\mathrm{\ζ}}_1\left(n\right)\right)}(R_{\mathrm{SD}}\left(n\right)-E\left({\mathrm{\ζ}}_1\left(n\right)\right))---(A-8)$

Here:

$R_{\mathrm{SD}}\left(n\right)\underset{k=1}{\overset{k}{\mathrm{\Σ}}}{h}_k\left(n\right)x_k\left(n\right)+{\mathrm{\σ}}^2;---(A-9)$

Then, with L _a(x ₁(n)) deinterleaving, solution spread spectrum, again substitution posterior probability channel decoder is deciphered, and obtains log-likelihood value L _e(b ₁(n));

(5) network code log-likelihood value stack:

${\tilde{L}}_e\left(b_1\left(n\right)\right)=L_{\mathrm{RD}}\left(b_1\left(n\right)\right)+L_e\left(b_1\left(n\right)\right)---(A-10)$

Again with spread spectrum as a result, interweaving obtains L _a(x ₁(n)), (A-2) formula of bringing into is again carried out next iteration;

Symbol description:

R _RD(n): via node is to the reception signal of base-station node, R _SD(n): the source is to the reception signal of base-station node, b _RD(n) be the junction network code signal, b ₁(n) be the data of targeted customer's node 1, b ₂(n) be the data of targeted customer's node 2, tanh: hyperbolic tangent function, E (x (n)): about the expectation of variable x (n), Var (x (n)): about the variance of variable x (n), ζ ₁(n): interference signal, for user node 1, E (ζ ₁(n)): interference signal average, Var (ζ ₁(n)): interference signal variance, L _a(x ₁(n)): targeted customer's node 1 modulation symbol x ₁(n) log-likelihood value, L _e(b ₁(n)): the log-likelihood value behind targeted customer's node 1 data decoding,

Via node receives the log-likelihood value of targeted customer's node 1 data after upgrading, h _k(n): k user's channel fading value, σ ²: noise variance.

2. method according to claim 1 is characterized in that in the described wireless relay system model, the baseband processing module of via node is comprised of receiver module and transmitter module unit; The radio-frequency module of receiver module receives wireless signal, and carries out intermediate frequency process, physical layer iterative interference cancellation, symbol de-maps, channel decoding judgement, and is sent to the media Access Layer and stores; The via node transmitter module will carry out linear network encoding, chnnel coding and sign map, finally by be emitted to the base-station node receiving terminal by intermediate frequency/RF processing unit.

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