CN101695016B - Multi-user random access system based on rateless codes and coding and decoding method thereof - Google Patents

Multi-user random access system based on rateless codes and coding and decoding method thereof Download PDF

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CN101695016B
CN101695016B CN 200910153394 CN200910153394A CN101695016B CN 101695016 B CN101695016 B CN 101695016B CN 200910153394 CN200910153394 CN 200910153394 CN 200910153394 A CN200910153394 A CN 200910153394A CN 101695016 B CN101695016 B CN 101695016B
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code
packet
decoding
information
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CN101695016A (en
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陈少磊
张朝阳
吴可镝
陈晓明
林泽
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浙江大学
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Abstract

本发明公开了一种基于无速率码的多用户随机接入系统及其编译码方法,利用无速率码的自适应链路适配特性,以及其编码时的随机特性,在各个用户发送机无需知道信道状态信息,以及在传输过程中无需任何反馈重传机制的条件下,能够自适应的调整各自的传输码率,且能够有效利用多个用户冲突重叠的信息,实现多个用户信息同时有效可靠的传输及正确的检测分离。 The present invention discloses a multi-user system and a random access method based on non-rate encoding and decoding codes, without using code rate adaptive link adaptation characteristics, its characteristics and the random coding, each user transmitter without know the channel state information, and the condition without any feedback mechanism retransmissions during transmission can adaptively adjust their transmission rate, a plurality of information can be effectively used and user conflicts overlap, while effectively implement a plurality of user information reliable separation of transmission and correct detection.

Description

基于无速率码的多用户随机接入系统及其编译码方法 A random access system and method for encoding and decoding based on the multi-user non-rate code

技术领域 FIELD

[0001] 本发明涉及无线通信领域,尤其涉及一种基于无速率码的多用户随机接入系统及其编译码方法。 [0001] The present invention relates to wireless communications, and in particular relates to non-rate code based on the random access multi-user system and method for encoding and decoding.

背景技术 Background technique

[0002] 在现代无线移动通信系统中,必须采用良好的多用户传输方式来保证多个用户同时有效可靠地传输信息。 [0002] In modern wireless mobile communication system, it must be a good multiuser transmission scheme to ensure that multiple users simultaneously transmit information efficiently and reliably. 传统的ALOHA技术虽然能够实现多用户单信道条件下的传输,但不能利用多个用户冲突或重叠的信息,效率不高。 While traditional ALOHA information technology enables transmission of a single multi-user channel conditions, but could not use a plurality of users coincide or overlap, the efficiency is not high. 而传统的CDMA(Code-DivisionMultiple-Access)传输方式,是通过不同的扩频序列来区分不同用户的信息,以完成多用户信息的接入传输。 The traditional CDMA (Code-DivisionMultiple-Access) transmission, the information is used to distinguish between different users with different spreading sequence in order to complete the multi-user access information transmission. Li Ping 提出的IDMA(Interleave-Division Multiple-Access)传输方式(见“ Interleave DivisionMul tip I e-Access^, IEEE Trans.Wireless Commun.,vol.5,n0.4,pp.938-947,Apr.2006.),则是不同用户通过使用不同的交织器,有效的利用用户混叠的信息,来实现不同用户的信号分离,以完成多用户信息的接入传输。但无论是CDMA还是IDMA,系统中每个用户所使用的都是传统的码率固定的编码方式,在进行信息传输之前,通常需要根据信道状态信息估计信道参数,根据信道参数设计一个码率固定为R的信道纠错编码。当估计的信道参数大于实际的信道参数时,虽然可以实现可靠传输,但是造成了传输的浪费,因为此时可以使用更高码率的信道纠错编码;当估计的信道参数小于实际的信道参数时,则不能实现可靠传输。为了使发送端得知信道的状态信息以设计码率固定的编码方式,以及在传输过程中 IDMA (Interleave-Division Multiple-Access) transmission scheme proposed by Li Ping (see "Interleave DivisionMul tip I e-Access ^, IEEE Trans.Wireless Commun., Vol.5, n0.4, pp.938-947, Apr. 2006.), it is different users by using different interleavers, effective use of aliasing user information to achieve the signal separation of different users, to complete the multi-user access transmission information, but the IDMA whether or CDMA, system, each user is using a conventional fixed-rate encoding mode, prior to information transfer, the information usually require estimating channel parameters based on the channel state, designing a fixed rate of error correction coding R channel according to a channel parameter. when the estimated channel parameter is greater than the actual channel parameters, although a reliable transmission but cause a waste of transmission because the channel error correction coding may use a higher code rate; when the estimated channel parameter is less than the actual channel parameters when, reliable transmission can not be achieved. in order to know the state of the transmission channel side information to design fixed-rate encoding mode, and a transmission process in 重传丢失的数据包,往往需要采用一定的反馈机制,例如ARQ (AutoRepeat-Request)等。 Retransmission of lost data packets, often need some feedback mechanism, for example, ARQ (AutoRepeat-Request) and the like.

发明内容 SUMMARY

[0003] 本发明的目的在于针对现有技术的不足,提供一种基于无速率码的多用户随机接入系统及其编译码方法,在各个用户发送机无需知道信道状态信息,以及在传输过程中无需任何反馈重传机制的条件下,能够自适应地调整各自的传输码率,且能够有效利用多个用户冲突重叠的信息,实现多个用户信息同时有效可靠的传输及正确的检测分离。 [0003] The object of the present invention is to deficiencies of the prior art, there is provided a non-rate code based on the random access multi-user system and method for encoding and decoding, each user need not know the transmitter channel state information, and during transmission under the conditions without any feedback retransmission mechanism can adaptively adjust their transmission rate, a plurality of information can be effectively used and user conflicts overlap, a plurality of user information to achieve the same time efficient and reliable transmission and detection of the correct separation.

[0004] 本发明的目的是通过以下技术方案来实现的:一种基于无速率码的多用户随机接入系统,由发送端和接收端组成。 [0004] The object of the present invention is achieved by the following technical solution: A non-rate code based on the random access multi-user system, the transmitting end and receiving end components. 其中发送端包含K (K为任意正整数)个单路输入、单路输出的发送机,接收端包含一个单路输入、K路输出的接收机。 Wherein the transmitting side comprises K (K is an arbitrary positive integer) single-input, single-output transmitter, the receiver comprising a single input, K-output receiver. 该系统运行于通信两端。 The system runs on both ends of the communication. 在发送端,每一个用户都拥有一个发送机,每个发送机的结构均相同。 At the transmitting end, each user has a transmitter, the transmitter of each structure are the same. 对于用户k(k =1,2,...,K),其发送机包括串行连接的编码器-k,映射器-k和接入控制器-k: For user k (k = 1,2, ..., K), which transmitter includes an encoder -k serially connected, and the access controller mapper -k -k:

[0005] 编码器_k,用于将用户k的消息数据包编为源源不断产生的Rateless Code编码包,其输入端接外部消息数据包的数据流,其输出端接至映射器_k的输入端; [0005] _k encoder, for the message data package compiled for user k continuing flow Rateless Code coded packet data stream input connected external message packet to the output end of the mapper _k an input terminal;

[0006] 映射器_k,用于完成由编码包数据比特到编码包传输符号的映射,可用通常的线性调制映射器来实现,其输入端接编码器-k的输出端,其输出端接至接入控制器-k的输入端;[0007] 接入控制器_k,主要完成对编码包的发送控制,即按事先确定的概率随机决定是否将当前编码包在当前时隙中接入信道进行发送,其输入端接映射器_k的输出端,其输出端接至信道; [0006] _K mapper, for performing mapping of bits to symbols coded packet transmission, by the usual linear modulation mapper implemented by encoding a data packet, encoder input connected -k output terminal, an output end access to the input of the controller -k; [0007] _K access controller, mainly to complete transmission of the control code packet, i.e. by the probability determined in advance to decide whether the current random access code packet in the current slot transmission channel, which input and output mapper _k end, the output end to the channel;

[0008] K个用户的发送机并行接入信道,组成系统的发送端。 [0008] K-user concurrent access channel transmitter, the composition of the transmission side system.

[0009] 在接收端,其单路输入、K路输出的接收机在内部分为并行的K路,每一个用户都对应其中相应的一路,并具有相同的结构。 [0009] At the receiving end, which is a single input, K-output receiver in the inside path into K parallel, each corresponding to a respective user which way and have the same structure. 对于用户k(k = 1,2,...,K),其所对应的那一路结构包括串行连接的解映射及译码软信息估计器_k和判决译码器_k: For user k (k = 1,2, ..., K), it corresponds to the way that the structure comprises a soft demapping and decoding information estimator and a decision decoder _k _k connected in series:

[0010] 解映射及译码软信息估计器-k,用于根据接收到的来自信道的混叠编码包完成各用户信号分离,以及通过解映射完成对用户k的编码包比特Log似然比软信息的估计,其输入端接接收机的来自于信道的输入以及除了判决译码器_k之外其余各判决译码器的软信息输出端,其输出端接至判决译码器_k的输入端; [0010] the soft demapping and decoding information estimator -k, for performing signal separation for each user according to the received code packets aliasing from the channel, and by demapping the encoded packet complete bit user k Log Likelihood Ratio estimated soft information, the receiver input connected to an input from the channel and in addition to the rest of the soft decision decoder _k output of each decision information decoder, which decoder output termination to decision _k an input terminal;

[0011] 判决译码器-k,用于完成对用户k编码包的译码,其输入端接解映射及译码软信息估计器-k的输出端,其判决结果输出端输出译码结果,作为接收机的一路输出,其软信息输出端接至除了解映射及译码软信息估计器-k之外的其余各解映射及译码软信息估计器的输入端; [0011] -k decision decoder, for performing decoding of user k code packets, the input and output end demapping and decoding estimator -k soft information, the decision result output terminal decoding result , as one output of the receiver, which outputs soft information to the remaining end demapping and decoding the soft information estimator input except demapping and decoding the soft information estimator -k;

[0012] K路结构并行构成接收机,组成系统的接收端。 [0012] K parallel passage structure constituting a receiver, the receiving end of the system composition.

[0013] 我们把这种基于无速率码的多用户随机接入系统简称为RMA(RatelessMultiple-Access)系统。 [0013] We call this a random access multi-user systems based on non-rate code referred to as RMA (RatelessMultiple-Access) system.

[0014] 一种上述基于无速率码的多用户随机接入系统的编译码方法,包括编码方法和译码方法。 [0014] None of the above multi-user based on a random access system code rate encoding and decoding method, comprising the encoding method and decoding method. 在发送端,按照编码方法完成各用户的编码接入,将各用户的编码包接入信道进行发送;在接收端,按照译码方法,根据接收到的混叠编码包,完成各用户编码包的检测分离和译码; At the transmitting end, according to the encoding method to complete the access of each user, each user's access code packet transmission channel; at the receiving end, in accordance with the decoding method, according to the received code packets aliasing complete coding each user packet detection and decoding separation;

[0015] 编码方法如下:设每个用户的发送机均需要发送m个消息数据包,每个消息数据包由b个数据比特组成,其中包括一个循环冗余校验码,用于译码器判断译码是否成功,用dk(i)表示消息数据包,其中i为消息数据包的编号(i = 1,2,..., m),下标k为用户的编 [0015] The coding method is as follows: a transmitter provided for each user needs to send all messages of m data packets, each message packet consists of b bits of data, which includes a cyclic redundancy check code decoder for judging whether the decoding is successful, a message indicating a packet DK (i), where i is the number of message packets (i = 1,2, ..., m), the subscript k is a user programmed

可(k = I,2,...,K); It may be (k = I, 2, ..., K);

[0016] 考虑其中的第k个用户(k= 1,2,...,K),按照如下步骤进行编码接入: [0016] Consider one of the k-th user (k = 1,2, ..., K), the access encoded following steps:

[0017] I)利用编码器_k进行编码; [0017] I) _k encoded by the encoder;

[0018] 将消息数据包dk⑴送入编码器-k,通过Rateless编码方式(如LT Code,RaptorCode等),得到源源不断产生的编码包序列以及该码的Tanner图,用vk(s)表示编码所得的编码包,其中s为编码包的编号(s = 1,2,...),下标k为用户的编号(k = 1,2,...,K); [0018] A message sent to an encoder packet dk⑴ -k, by Rateless encoding (e.g. LT Code, RaptorCode, etc.), to give the coding sequence of packets and a Tanner graph of the code steady stream generated by an encoding vk (s) the resultant coded packets, where s is the number of code packet (s = 1,2, ...), the subscript k is the number of users (k = 1,2, ..., K);

[0019] 各用户独立完成自己的编码过程,编码时使用不同于其他用户的随机数生成器,以得到与其他用户不同的、相互独立的Tanner图,这样可以保证各用户信号的不相关性,为译码时各用户的信号分离提供可行性; [0019] each user independently own coding process, using a different random number generator users coding, to give users different from the other, independent Tanner graph, which can not guarantee the relevance of each user signal, to provide the decoding signal separating feasibility of each user;

[0020] 2)利用映射器_k,进行由编码包数据比特到编码包传输符号的映射; [0020] 2) using the mapper _k, the bit of the code packet transmission symbols mapped by the encoded data packet;

[0021] 将由编码器_k得到的编码包Vk(S)送入映射器_k,映射方式可采用普通的线性调制方式(如BPSK、QPSK等),完成由编码包数据比特到编码包传输符号的映射:Vk(S) — Wk(S),其中S为编码包的编号(S = 1,2,...),下标k为用户的编号(k = 1,2,...,K); [0021] The code packets Vk (S) obtained by the encoder into _k _k mapper, mapping mode can be an ordinary linear modulation scheme (e.g., BPSK, QPSK, etc.), done by the coded bits to encode the packet data packet transmission symbol mapping: Vk (S) - Wk (S), where S is the number of code packet (S = 1,2, ...), the subscript k is the number of users (k = 1,2, ... , K);

[0022] 3)利用接入控制器_k,进行对编码包的发送控制; [0022] 3) using the access controller _k, transmission control code packet;

[0023] 将由映射器-k得到的经过映射的编码包Wk (S)送入接入控制器_k,在任一个时隙j (j = I,2,...),用户k以概率pk顺序将Wk (s)接入信道发送:用xk (j)表示用户k在时隙j经信道发送的符号,如果决定在当前时隙j将编码包Wk(S)接入信道,则在编码包Wk(S)包头增加K个比特的用户标示信息,其中第k位置1,其余各位置0,组成发送编码包Wk' (S),令xk(j) =Wk' (s),在下一个时隙判断是否将wk(s+l)接入信道;否则令xk(j) =0,下一个时隙继续判断是否将Wk (S)接入信道; [0023] obtained by the mapper -k encoded packet Wk (S) is mapped into the access controller _k, at any one time slot j (j = I, 2, ...), the user k with probability pk sequentially Wk (s) an access channel transmission: a user indicates a symbol j in a slot k transmitted via a channel with XK (j), j if the decision in the current time slot code packet Wk (S) access channel, then the coding package Wk (S) header increased K bits of user designation information, wherein the k-th position 1, the rest position 0, the composition of the transmission code packet Wk '(S), so that xk (j) = Wk' (s), the next slot determines whether wk (s + l) access channel; else let xk (j) = 0, the next time slot continues to determine whether wk (S) access channel;

[0024] 由于采用的是Rateless编码方式,所以经过编码及映射后的序列五k = {wk(l),wk (2),...,wk (s),...}是源源不断产生的,于是经信道发送的序列= Ixk(I),xk(2),...,xk(j),...}也是源源不断的,长度并不是固定的,Ik的每一个长度都对应相应的一个码率; [0024] As a result of Rateless encoding, the encoded sequence after mapping five and k = {wk (l), wk (2), ..., wk (s), ...} is a continuing flow , so the sequence of channel transmission by the letter = Ixk (I), xk (2), ..., xk (j), ...} is a steady stream of length is not fixed, each of a length corresponding to Ik are a corresponding rate;

[0025] 每个用户的发送机根据以上规则,源源不断的产生编码包并接入信道,直至接收端告知它停止发送。 [0025] each user transmitter according to the above rules, a steady stream of code packets and generate an access channel, to inform the receiving terminal until it stops to send.

[0026] 译码方法如下: [0026] The decoding method is as follows:

[0027] 接收机接收到来自信道的,源源不断的,各个用户相互混叠且加上了噪声的编码包,各用户的信号分离及译码同时进行,对于用户k(k = 1,2,...,K),其判决译码器_k采用和编码器_k相同的随机数生成器,所以可以准确的重构该码的Tanner图,按照如下步骤进行信号分离和译码: [0028] I)接收机首先接收到N = m个来自信道的混叠编码包; [0027] The receiver receives the incoming from the channel, a steady stream of each user and each added aliasing noise code packet, each user's signal separating and decoding the same time, for user k (k = 1,2, ..., K), which decision decoder and the encoder _k _k using the same random number generator, it is possible to accurately reconstruct the Tanner graph of the code, a demultiplexing and decoding the following steps: [ 0028] I) a receiver first receives the number N = m channels from aliasing code packet;

[0029] 2)接收机再接收Δ N个混叠编码包,令N = N+Λ N,此时的码率为'及=2 ; [0029] 2) a receiver then receives the aliasing Δ N encoding packets, so that N = N + Λ N, code rate is in this case 'and a = 2;

N N

[0030] 3)将接收到的编码包送入解映射及译码软信息估计器_k,采用“基于无速率码的多用户随机接入系统的译码软信息估计方法”,在当前码率R下进行运算,利用除了判决译码器-k之外其余各用户的判决译码器的输出软信息(初始化时为O),更新估计软信息; [0030] 3) the received coded packet into the soft demapping and decoding information _K estimator, a "multi-user non-rate code based on the random access method of estimating the soft information decoding system", the current code It calculates the ratio R, in addition to using -k decision decoder outputs a soft decision information of each user to rest decoder (initialization is O), soft information updating estimates;

[0031] 4)将由解映射及译码软信息估计器_k更新得到的估计软信息作为判决译码器_k的输入,在重构的当前码率R下的Tanner图上运行BP(Belief-Propagation)译码算法,完成一轮迭代译码运算,并更新判决译码器_k的输出判决结果信息和输出软信息; [0031] 4) soft demapping and decoding information obtained by updating _k estimator estimates soft decision information as inputs _k decoder, operating on the Tanner graph in the reconstructed current code rate R BP (Belief -Propagation) decoding algorithm, an iterative decoding operation is completed, and the update result information and outputs a soft decision information decoder output decision _k;

[0032] 5)利用判决译码器-k的输出判决结果信息判断译码结果是否满足Tanner图中校验节点所限制的校验关系,或者迭代次数已经达到所限定的最大次数,如果满足上述两个条件之一,则转入步骤6);否则转入步骤3); Output decision decoding result determination result information [0032] 5) using the decision decoder meets check -k relation restricted check node in the Tanner graph, or the maximum number of iterations has reached a defined, if they meet the above one of two conditions, the process proceeds to step 6); otherwise, go to step 3);

[0033] 6)利用各个包内的循环冗余校验码判断数据包是否都译码正确,如果都正确,转入步骤7);否则转入步骤2); [0033] 6) using a cyclic redundancy check code in each packet determines whether the decoded data packets are correct, if correct, go to step 7); otherwise, go to step 2);

[0034] 7)译码结束,接收机发送一个信号告知用户k的发送机停止发送。 [0034] 7) the end of decoding, the receiver sends a signal to inform the user k transmitter stops transmitting.

[0035] 所述基于无速率码的多用户随机接入系统的译码软信息估计方法如下: [0035] Based on the code rate of the non-random access multi-user estimating method of decoding the soft information system is as follows:

[0036] 我们设接收机接收到来自信道的,源源不断的,各用户混叠且加上了噪声的编码包序列为I = {y (I), y (2),..., y (j),...}: [0036] We set the receiver to receive incoming from the channel, a steady stream of each user and aliasing noise added packet sequence coding for I = {y (I), y (2), ..., y ( j), ...}:

— K - K

[0037] y(J) = Yjh.Xi(JXf) (y = 1,2,...)../=1 [0037] y (J) = Yjh.Xi (JXf) (y = 1,2, ...) ../= 1

[0038] 其中j为时隙标号,下标i为用户的编号(i = 1,2,...K) ,Xi = Ixi (I) ,Xi0..,Xi(J),...1为第i个用户经信道发送的源源不断的序列,h为信道参数,η= {η (I),η(2),..., n(j),...}为均值为O,方差为σ 2的白高斯噪声序列; [0038] wherein j is a slot index, the subscript i is the number of users (i = 1,2, ... K), Xi = Ixi (I), Xi0 .., Xi (J), ... 1 steady stream sequence is transmitted by the i th user channel, h is the channel parameters, η = {η (i), η (2), ..., n (j), ...} is the mean value is O, white Gaussian noise with variance σ 2 of the sequence;

[0039] 在接收机,我们根据任一时隙j接收到的编码包包头的用户标示信息,判断出该时隙各用户的信道接入状况(对包头K个比特作硬判决,第k(k= 1,2,...,K)位比特判决结果为I表示第k个用户接入了信道,为O表示第k个用户没有接入信道),然后去掉用户标示信息;用Jk表示用户k(k = 1,2,..., K)的编码包接入时隙的集合: [0039] At the receiver, we receive a time slot according to any j code packet header user designation information, it is determined that the channel status of each user access to the slots (K bits of the header as a hard decision, the k (k = 1,2, ..., K) bits for the decision result I represents the k-th user access channel, is O represents the k-th user has no access channel), and then remove the user designation information; Jk represented by user k (k = 1,2, ..., K) of the set of code packet access slot:

[0040] Jk = {j xk(j)关O, j = 1,2,...} = {Jk(l), Jk(2),..., Jk(qk),...} [0040] Jk = {j xk (j) Off O, j = 1,2, ...} = {Jk (l), Jk (2), ..., Jk (qk), ...}

[0041] 其中qk为集合Jk中元素的编号(qk = 1,2,...),下标k为用户的编号(k = 1, [0041] where qk is the number of elements in the set Jk (qk = 1,2, ...), the subscript k is the number of users (k = 1,

2,..., K); 2, ..., K);

[0042] 对于每一个用户,我们要在接收机接收到不同长度的编码包序列X时,即在不同的码率R下,计算其解映射及译码软信息估计器的输出估计软信息,对用户k,设接收机已经接收了N个编码包I = {y (I), y (2),..., y(N)},则当前的码率为R = m/N ; When [0042] For each user, we have to receive different lengths of coding sequence of packets at the receiver X, i.e., at a different code rate R, which is calculated demapping and outputs the decoded soft information estimator estimates soft information, for user k, the receiver has received a set of N code packet I = {y (I), y (2), ..., y (N)}, then the current code rate is R = m / N;

[0043] 对于其接入时隙集合Jk中的每一个时隙Jk(qk),其接收到的混叠编码包y (Jk(Qk)),可以写作: [0043] for which the access slot set for each time slot Jk (qk) Jk in which the received code packets aliasing y (Jk (Qk)), can be written as:

Figure CN101695016BD00101

[0046] 其中4k(Jk(qk))为在时隙Jk(qk),非零的其他用户信号和高斯白噪声之和,我们将其称为合并噪声且近似视其为高斯随机变量,均值记为E[ 4k(Jk(qk))],方差记为Var [ ζ k (Jk (qk))],于是可以将接收编码包y (Jk (qk))也视作符合高斯特性: [0046] wherein 4k (Jk (qk)) as slot Jk (qk), other user signals and white Gaussian noise of zero sum, we call them as combined noise and approximately Gaussian random variable with mean referred to as E [4k (Jk (qk))], referred to as the variance Var [ζ k (Jk (qk))], then the packet may be received encoded y (Jk (qk)) is also regarded as a Gaussian characteristics:

Figure CN101695016BD00102

[0050] 在解映射及译码软信息估计器_k中,首先按照所选用的映射方式所对应的均值运算规则1^和方差运算规则rvm,由其余各用户编码包的比特log似然比软信息,算出其余各用户编码包的映射符号的均值和方差;然后按照所选用的映射方式所对应的解映射规则F,由接收到的混叠编码包和已经算出的其余各用户编码包的映射符号的均值和方差,根据接收编码包符合的高斯特性,估计出用户k编码包的比特log似然比软信息。 [0050] In the soft demapping and decoding information estimator _k, a first embodiment according to the selected mapping rules corresponding to the arithmetic mean and variance 1 ^ RVM operational rule, the remaining bits of the encoded packet for each user log likelihood ratio soft information, calculates the mean and variance of the remaining symbol mapping for each user code packet; then, according to a demapping rule selection of mapping mode corresponding F., by the received remaining user aliasing code packet and already calculated code packet mean and variance of the symbols are mapped, according to a Gaussian characteristic of the received code packets compliant, estimated user k code packets bit log likelihood ratio of the soft information.

[0051] 在第a次迭代时,按照“估计软信息更新表达式” [0051] When a first iteration, according to "soft information update estimated expression"

Figure CN101695016BD00103

[0058] 更新估计软信息,式中LLRka(v(qk))为用户k第a次迭代译码所需的由解映射及译码软信息估计器_k估计出的第qk个编码包的比特log似然比软信息矢量,Li^ (V (¾))为用户i第a-Ι次迭代译码后的第1个编码包的比特log似然比软信息矢量(初始化a =I 时,<(v⑷)=0); [0058] updating estimates soft information, wherein LLRka (v (qk)) necessary for decoding iteration of a user k by the soft demapping and decoding information estimator _k estimated first encoded packet qk bit soft log likelihood ratio information vector, Li ^ (V (¾)) is the bit i of a user after log a-Ι iterations of decoding a code packet likelihood than the soft information vector (initialization a = i , <(v⑷) = 0);

[0059] 如果映射方式采用BPSK,将具体的均值运算规则Γ E,BPSK,方差运算规则Γ VarjBPSK以 [0059] If the mapping mode using BPSK, the specific rules of arithmetic mean Γ E, BPSK, variance calculation rules to Γ VarjBPSK

及解映射规则Fbpsk代入“估计软信息更新表达式”,可以得到其具体的表达形式: And de-mapping rules Fbpsk substituting "soft information update estimated expression" can get their specific form of expression:

[0060] [0060]

Figure CN101695016BD00111

[0061] (qk = 1,2,...1 Jk|c = I,2,..., b) [0061] (qk = 1,2, ... 1 Jk | c = I, 2, ..., b)

[0062] 其中y(Jk(qk))(。)表示在时隙Jk(qk)接收到的混叠编码包y中的第C个符号,LLRka (V (qk) (c))为用户k第a次迭代译码所需的由解映射及译码软信息估计器_k估计出的第qk个编码包的第c个比特的log似然比软信息,L^1 (V (¾) (c))为用户i第a-Ι次迭代译码后的第Qi个编码包的第c个比特的log似然比软信息。 [0062] where y (Jk (qk)) (.) Denotes (QK) received in a slot Jk aliasing in the first code packets C y symbol, LLRka (V (qk) (c)) for the user k estimated by the soft demapping and decoding of information estimator _k c qk bits of encoded packets of a log times required than the soft iterative decoding likelihood information, L ^ 1 (V (¾) (c)) to the c-th bit after the first user i a-Ι Qi iterations of decoding encoded packets soft log likelihood ratio information.

[0063] 如果映射方式采用QPSK,则将具体的均值运算规则Γ E,QPSK,方差运算规则rvm,QPSK以及解映射规则Fqpsk代入“估计软信息更新表达式”,可以得到其具体的表达形式: [0063] If the mapping mode using QPSK, then the mean specific arithmetic rule Γ E, QPSK, variance calculation rules rvm, QPSK demapping rule Fqpsk and substituting "soft information estimation updating expression", which can be specific expressions:

[0064] [0064]

[0065] [0065]

Figure CN101695016BD00112

[0066] (qk = 1,2,...Jk | c = 1, 2,..., b/2) [0066] (qk = 1,2, ... Jk | c = 1, 2, ..., b / 2)

[0067] 其中,y(Jk(qk))(c)表示在时隙Jk(qk)接收到的混叠编码包y中的第C个符号,LLRka (V (qk) (2c_d)、LLRka(v(qk) (2c))为用户k第a次迭代译码所需的由解映射及译码软信息估计器_k估计出的第qk个编码包的奇数位和偶数位比特的log似然比软信息,L^1 (V (¾)(2。_1})、L^1 (V(¾) (2c))为用户i第a-Ι次迭代译码后的第Qi个编码包的奇数位和偶数位比特的log似然比软信息,Re[.]表示取实部运算,Im[.]表示取虚部运算; [0067] where, y (Jk (qk)) (c) represented by aliasing in a time slot code packet y Jk (qk) of the received C symbol, LLRka (V (qk) (2c_d), LLRka ( even bit and odd bit bit log v (qk) (2c)) necessary for decoding iteration of a user k estimated by the demapping and decoding the first soft information estimator _k qk encoded packet like soft information likelihood ratio, L ^ 1 (V (¾) (2._1}), L ^ 1 (V (¾) (2c)) after the first user i, a-Ι iterative decoding of coded packets Qi [.] of the even bit and odd bit log likelihood ratio of bit soft information, Re denotes the real part operator taking, Im represents the imaginary part taking operation [.];

[0068] 然后将估计软信息矢量LLRka (V (qk))作为判决译码器_k的输入软信息矢量Lkin'a(qk),即令= LLRak(v(qk)),送入判决译码器_k进行第a次的迭代译码;其余各用户也按此同样操作,各用户译码同时进行;完成第a次迭代后,对于用户k,得到其判决译码器_k的输出软信息矢量Lk°ut'a(qk),令4(v⑷)) = ΐΓ'α(&),其余用户也按此同样操作,接着将相应的值代入“估计软信息更新表达式”,开始新一次(第a+Ι次)的迭代,以此类推,直至判决译码器_k的译码结果满足Tanner图中校验节点所限制的校验关系或者迭代次数达到所限定的最大次数;[0069] 这样可以完成码率R = m/N下的软信息估计,由于编码方式的Rateless属性,其编码包序列长度N是不断变化的,我们可以在不同的接收编码包长度下,即各个码率下,运行各自对应的运算,从而完成各个码率下的软信息估计,进而完成信 [0068] Then the estimated information vector soft LLRka (V (qk)) as an input soft decision information decoder _k vector Lkin'a (qk), and even if = LLRak (v (qk)), into the decision decoding _k is a first iterative decoding times; Click to the remaining users in the same manner, simultaneously decoding each user; after a completion of the first iteration, for user k, which is to give the soft output decision decoder of _k information vector Lk ° ut'a (qk), so that 4 (v⑷)) = ΐΓ'α (&), the remaining user Click same manner, then the appropriate values ​​are substituted into "updated soft information estimation expression" to start a new a (a + Ι second th) iteration, and so on until the decoder decoding result decision _k meet the maximum number of the Tanner graph the relationship between the check or check node restricted number of iterations reaches the defined; [ 0069] this soft information to complete the code rate R = m / N of the estimated property since Rateless encoding method, which encodes the packet sequence length N is constantly changing, we can receive different length code packet, i.e. each symbol lower rate, each corresponding arithmetic operation, thereby completing the soft information estimated at each code rate, thereby completing the letter 号分离和译码。 Demultiplexer and decoding.

[0070] 本发明的有益效果是:本发明充分利用无速率码的自适应链路适配特性,以及其编码时的随机特性一不同用户的无速率码编码包是按照一定方式随机生成的、互不相关的这一特性,在各个用户发送机无需知道信道状态信息,以及在传输过程中无需任何反馈重传机制的条件下,能够自适应的调整各自的传输码率,且能够有效利用多个用户冲突重叠的信息,实现多个用户信息同时有效可靠的传输及正确的检测分离。 [0070] Advantageous effects of the invention are: full advantage of the present invention, no code rate adaptive link adaptation characteristics, and the stochastic characteristics of different users that encodes a rateless code encoding manner according to a certain packet is randomly generated, unrelated to this feature, each user need not know the transmitter channel state information, and the condition without any feedback mechanism retransmissions during transmission can adaptively adjust their transmission rate, and can be effectively used multiple user conflict overlapping information, information of a plurality of users simultaneously achieve efficient and reliable transmission and detection of the correct separation.

附图说明 BRIEF DESCRIPTION

[0071] 图1是RMA系统的具体结构框图; [0071] FIG. 1 is a block diagram showing a specific structure of the RMA system;

[0072] 图2是RMA系统采用LT Code编码时,其LT Code的Tanner图 [0072] FIG. 2 is a system using RMA encoding LT Code, which Tanner graph LT Code

[0073] 图3是RMA系统采用Raptor Code编码时,其外码部分的LDPC Code的Tanner图; [0073] FIG. 3 is a system using RMA Raptor Code encoding, LDPC Code outer Tanner graph of the code portion;

[0074] 图4是RMA系统采用Raptor Code编码时,其内码部分的LT Code的Tanner图; [0074] FIG. 4 is a system using RMA Raptor Code encoder, LT Code Tanner graph of the code portion thereof;

[0075] 图5是RMA系统米用Raptor Code编码时,其Raptor Code的整体Tanner图; [0075] FIG. 5 is a system RMA meters encoding Raptor Code, which Raptor Code overall Tanner graph;

[0076] 图6是采用Raptor Code的RMA系统(各用户均采用BPSK调制方式,以概率I接入,码率R = 1/16时)与采用Zigzag Code的IDMA系统(各用户Rzigzag = 1/2,8倍扩频,码率R= 1/16)在各信噪比下的误比特率对比图,用户数K = 2 ; [0076] FIG 6 is the use of RMA Raptor Code system (each user adopts BPSK modulation scheme, the access probability I, when code rate R 1/16 =) and the IDMA system uses Zigzag Code (each user Rzigzag = 1 / 2,8 times the spreading code rate R = 1/16) in the SNR at each bit error rate comparison chart, the number of users K = 2;

[0077] 图7是采用Raptor Code的RMA系统(各用户均采用BPSK调制方式,以概率I接入,码率R = 1/16时)与采用Zigzag Code的IDMA系统(各用户Rzigzag = 1/2,8倍扩频,码率R= 1/16)在各信噪比下的误比特率对比图,用户数K = 4。 [0077] FIG. 7 is a system using Raptor Code of RMA (each user are used in BPSK modulation scheme, the access probability I, when code rate R 1/16 =) and the IDMA system uses Zigzag Code (each user Rzigzag = 1 / 2,8 times the spreading code rate R = 1/16) bit error rate vs. signal to noise ratio at each FIG., the number of users K = 4.

具体实施方式 Detailed ways

[0078] 以下参照附图对本发明作进一步描述,本发明的目的和效果将变得更加明显。 DRAWINGS The invention will be further described [0078] below with reference to the object and effect of the present invention will become more apparent.

[0079] 无速率码(Rateless Code)是一种具有自适应链路适配特性的新型信道编码方式。 New channel coding scheme [0079] None rate code (Rateless Code) is an adaptive link adaptation characteristics. 它与传统的码率固定的编码方式最大的不同在于它在发送端不设定固定码率,其编码包的个数是没有限制的。 With the traditional fixed encoding rate biggest difference is that at the transmission side does not set a fixed rate, the number of code packet which is not limited. 发送端可以按照一定方式源源不断的随机产生编码包并发送出去。 The transmit end can generate a random code packets according to a certain manner, and a steady stream of sent. 接收端则可以在接收到这些编码包后尝试译码。 Receiving end may attempt to decode after receiving the code packet. 从统计意义上来讲,每一个编码包包含着相同的关于消息数据包的信息量,接收端并不关心具体的某一个编码包的接收情况,而是关心接收到的编码包的总数量,因此在传输过程中无需反馈和重传的机制。 Statistically speaking, each coded bag mouth same amount of information about the message packet, the receiving side does not care about the specific case of receiving a certain code packet, but about the total number of received code packets, thus without feedback and retransmission mechanisms during transmission. 只要接收端接收到足够多的编码包,就可以成功译码;如果译码失败,接收端可以再多接收一些编码包然后继续尝试译码。 As long as the receiving end has received enough code packets, it can be successfully decoded; If the decoding fails, the receiver can receive some more coded packet and continue to try to decode. 接收端将一直重复这个过程直到译码成功。 The receiving end will repeat this process until the decoding is successful. 一旦译码成功,接收端只需要发送一个非常简单的信号告知发送端停止发送即可,这样就完成了整个传输过程。 Upon successful decoding, the receiver only needs to send a very simple signal that the transmitting side can stop transmission, thus completing the entire transmission process. 此时,实际传输的码率取决于实际发送的编码包数目,而实际发送的编码包数目取决于当时的信道状况。 In this case, the actual transfer rate depends on the number of packets actually transmitted coded, the coding depends on the number of packets actually transmitted when channel conditions. 由此可见,采用无速率码编码方式,可以在发送端不知道任何信道状态信息,以及在传输过程中无需任何反馈重传机制的条件下,自适应地调整传输码率,保证信息有效可靠的传输。 Thus, without using code rate encoding, at the transmitting end you can not know any channel state information, and the condition without any feedback mechanism retransmissions during transmission, the transmission rate is adaptively adjusted to ensure effective and reliable information transmission.

[0080] 参照图1,一个包含K (K为任意正整数)个用户的RMA系统,由发送端和接收端构成。 [0080] Referring to FIG. 1, comprising a K (K is an arbitrary positive integer) of the user RMA system having a transmitting end and a receiving end. 其中发送端包含K个单路输入、单路输出的发送机,接收端包含I个单路输入、K路输出的接收机。 Wherein the transmitting side comprises K single-input, single-output transmitter, the receiver comprising I a single input, K-output receiver. 该系统运行于通信两端。 The system runs on both ends of the communication. 在发送端,每一个用户都拥有一个发送机,每个发送机的结构均相同。 At the transmitting end, each user has a transmitter, the transmitter of each structure are the same. 对于用户k(k = 1,2,...,K),其发送机包括串行连接的编码器-k,映射器_k和接入控制器_k: For user k (k = 1,2, ..., K), which transmitter includes an encoder -k serially connected, and the access controller mapper _k _k:

[0081] 编码器_k,用于将用户k的消息数据包编为源源不断产生的Rateless Code编码包,其输入端接外部消息数据包的数据流,其输出端接至映射器_k的输入端; [0081] _k encoder, for the message data package compiled for user k continuing flow Rateless Code coded packet data stream input connected external message packet to the output end of the mapper _k an input terminal;

[0082] 映射器_k,用于完成由编码包数据比特到编码包传输符号的映射,可用通常的线性调制映射器来实现,其输入端接编码器-k的输出端,其输出端接至接入控制器-k的输入端; [0082] _K mapper, for performing mapping of bits to symbols coded packet transmission, by the usual linear modulation mapper implemented by encoding a data packet, encoder input connected -k output terminal, an output end -k to the input of the controller of the access;

[0083] 接入控制器_k,主要完成对编码包的发送控制,即按事先确定的概率随机决定是否将当前编码包在当前时隙中接入信道进行发送,其输入端接映射器_k的输出端,其输出端接至信道; [0083] _K access controller, mainly to complete transmission of the control code packet, i.e. by the probability determined in advance to decide whether the current random code packet transmitted in the current slot access channel, input connected mapper _ k of the output terminal, its output end to the channel;

[0084] K个用户的发送机并行接入信道,组成系统的发送端。 [0084] K-user concurrent access channel transmitter, the composition of the transmission side system.

[0085] 在接收端,其单路输入、K路输出的接收机在内部分为并行的K路,每一个用户都对应其中相应的一路,并具有相同的结构。 [0085] At the receiving end, which is a single input, K-output receiver in the inside path into K parallel, each corresponding to a respective user which way and have the same structure. 对于用户k(k = 1,2,...,K),其所对应的那一路结构包括串行连接的解映射及译码软信息估计器_k和判决译码器_k: For user k (k = 1,2, ..., K), it corresponds to the way that the structure comprises a soft demapping and decoding information estimator and a decision decoder _k _k connected in series:

[0086] 解映射及译码软信息估计器_k,用于根据接收到的来自信道的混叠编码包完成各用户信号分离,以及通过解映射完成对用户k的编码包比特Log似然比软信息的估计,其输入端接接收机的来自于信道的输入以及除了判决译码器_k之外其余各判决译码器的软信息输出端,其输出端接至判决译码器_k的输入端; [0086] the soft demapping and decoding information _K estimator, for performing signal separation for each user according to the received code packets aliasing from the channel, and by demapping the encoded packet complete bit user k Log Likelihood Ratio estimated soft information, the receiver input connected to an input from the channel and in addition to the rest of the soft decision decoder _k output of each decision information decoder, which decoder output termination to decision _k an input terminal;

[0087] 判决译码器_k,用于完成对用户k编码包的译码,其输入端接解映射及译码软信息估计器_k的输出端,其判决结果输出端输出译码结果,作为接收机的一路输出,其软信息输出端接至除了解映射及译码软信息估计器_k之外的其余各解映射及译码软信息估计器的输入端; [0087] _k decision decoder, for performing decoding of user k code packets, the input and output end demapping and decoding the soft information estimator _k, the decision result output terminal decoding result , as one output of the receiver, which outputs soft information to the remaining end demapping and decoding the soft information estimator input except demapping and decoding the soft information estimator _k;

[0088] K路结构并行构成接收机,组成系统的接收端。 [0088] K parallel passage structure constituting a receiver, the receiving end of the system composition.

[0089] 上述基于无速率码的多用户随机接入系统的编译码方法包括编码方法和译码方法。 [0089] Based on the above multi-user non-random access code rate encoding and decoding system comprising the encoding method and decoding method. 在发送端,按照编码方法完成各用户的编码接入,将各用户的编码包接入信道进行发送;在接收端,按照译码方法,根据接收到的混叠编码包,完成各用户编码包的检测分离和译码。 At the transmitting end, according to the encoding method to complete the access of each user, each user's access code packet transmission channel; at the receiving end, in accordance with the decoding method, according to the received code packets aliasing complete coding each user packet detection and decoding separation.

[0090] 编码方法如下:设每个用户的发送机均需要发送m = 1024个消息数据包,每个消息数据包由b = 128个数据比特组成,其中包括一个循环冗余校验码,这个循环冗余校验码采用CRC16,用于译码器判断译码是否成功,用dk(i)表示消息数据包,其中i为消息数据包的编号(i = 17 2, , 1024),下标k为用户的编号(k = 1,2,...,K); [0090] The coding method is as follows: a transmitter provided for each user needs to send all messages m = 1024 packets, each message packet consists of b = 128 data bits, which comprises a cyclic redundancy check code, this using the CRC16 cyclic redundancy check code, the decoder determines whether the decoding is successful, a message indicating a packet DK (i), where i is the number of message packets (i = 17 2,, 1024), the subscript k is the number of users (k = 1,2, ..., K);

[0091] 考虑其中的第k个用户(k= 1,2,...,K),按照如下步骤进行编码接入: [0091] Consider one of the k-th user (k = 1,2, ..., K), the access encoded following steps:

[0092] I)利用编码器_k进行编码; [0092] I) _k encoded by the encoder;

[0093] 将消息数据包dk⑴送入编码器-k,通过Rateless编码方式(如LT Code,RaptorCode等),得到源源不断产生的编码包序列以及该码的Tanner图。 [0093] A message sent to an encoder packet dk⑴ -k, by Rateless encoding (e.g. LT Code, RaptorCode etc.), a steady stream to give the coding sequence of packets generated and a Tanner graph of the code. 用vk(s)表示编码所得的编码包,其中s为编码包的编号(S= 1,2,...),下标k为用户的编号(k= 1, Encoding an encoding resulting coated with vk (s), where s is the number of code packet (S = 1,2, ...), the subscript k is the number of users (k = 1,

2,..., K)。 2, ..., K).

[0094] 实施例1:当编码米用LT Code时,按照如下方式进行编码:[0095] 对m = 1024个消息数据包进行LT编码,生成LT Code的Tanner图,并得到源源不断生成的LT Code的编码包。 [0094] Example 1: When m by encoding LT Code, be coded as follows: [0095] m = 1024 messages to the packet encoding LT, LT Code Tanner graph generated, and generated a steady stream to give LT Code code packet. 用Vk(S)表示LT Code的编码包,其中s为编码包的编号(s = 1,2,...),下标k为用户的编号(k= 1,2,...,K),编码方法为:要产生LT Code编码包Vk (S),首先按照度数分布Ω (X)(该分布的各参数如表I所示,其中01表示度数1所占的比例),用随机数生成器为其产生度数degk(S);然后用随机数生成器产生一个1024维二元域向量{<^}0_ = 1,2.„,1024),元素\的取值为“O”或者“,其中元素“!”的个数为Clegk(S)。 Represents coding LT Code coated with Vk (S), where s is the number of code packet (s = 1,2, ...), the subscript k is the number of users (k = 1,2, ..., K ), the encoding method: encoding packets to generate LT Code Vk (S), in accordance with the first frequency distribution Ω (X) (each of the parameters of this distribution is shown in table I, which represents the proportion of 01 degrees 1), by randomly number generator for generating degrees degk (S); 1024 and then generates a field of two-dimensional vector using a random number generator {<^} = 0_ 1,2 ", 1024), the element values ​​of \ to" O ". Alternatively number ", where the element"! "is Clegk (S). 元素为“I”表示对应的编号为i消息数据包dk(i)被选中,将这些被选中的消息数据包按比特作模2求和,即得到LT Code的编码包的值: Element of "I" indicates that the corresponding message packet number i DK (i) is selected, these selected bits of a message packet by modulo 2 summed to obtain the value of the code packet LT Code:

Figure CN101695016BD00141

[0098]表 I [0098] TABLE I

[0099] LT Code的Tanner图如图2所示。 [0099] LT Code Tanner graph shown in Fig. 图中有两类节点,圆圈表示变量节点(variablenode),变量节点又分为两类,上面一行为信息节点(information node),共有m= 1024个,记作Vu,Vk,2,, Vkjm,分别对应消息数据包dk(l),dk(2),...,dk(m),下面一行为编码节点(parity node),记作Pka7PkW..,Pk,s,...,分别对应LT Code 的编码包vk(l) ,Vk (2),...,vk(s),...;方框表示校验节点(check node),分别记作Ck>1, Ck,2,..., Ck,s,...,与每一个校验节点相连的各节点的校验和为O。 There are two types of nodes in FIG, circles represent variable nodes (variablenode), divided into two categories variable node, the node above a behavioral information (information node), a total of m = 1024 th, denoted as Vu, Vk, 2 ,, Vkjm, corresponding message packet dk (l), dk (2), ..., dk (m), following a behavior coding node (parity node), referred to as Pka7PkW .., Pk, s, ..., respectively LT Code code packet vk (l), Vk (2), ..., vk (s), ...; block represents a check node (check node), respectively referred to as Ck> 1, Ck, 2, ..., Ck, s, ..., each node with each node connected to a check and the check is O. 因此,在编码过程中用随机数生成器为每一个LT Code的编码包vk(s)选择degk(s)个消息数据包作模2求和,在Tanner图中就体现为为校验节点Ck, s选择degk(s)个信息节点相连。 Thus, each code packet LT Code vk (s) selected degk (s) message packet modulo 2 summation in the Tanner graph is as reflected in the check node Ck encoding process by the random number generator is connected degK s selection (s) the node number information. 而校验节点Ck, s与编码节点Pk, s的连接关系是固定的,Ck,s总是与Pk,s 对应的相连。 Is connected to check node relationship Ck, s and coding node Pk, s is fixed, is connected to Ck, s always Pk, s corresponding. 由于LTCode是一种Rateless编码,其编码包个数随着编码过程源源不断的增加,所以每产生一个新的LT Code编码包Vk(S),图中就会增加一个新的校验节点Ck,s和一个新的编码节点Pk,s,随着编码包源源不断的增多,Tanner图会越来越大。 Since a Rateless LTCode coding, which encodes the packet number increases with a steady stream of the encoding process, so each new LT Code to generate a coded packet Vk (S), the figure will increase to a new check node Ck, s and a new coding node Pk, s, with a steady stream of code packet increases, Tanner FIG growing.

[0100] 各用户独立完成自己的LT Code编码过程,编码时使用不同于其他用户的随机数生成器,以得到与其他用户不同的、相互独立的Tanner图,这样可以保证各用户信号的不相关性,为译码时各用户的信号分离提供可行性; [0100] each user to independently complete their LT Code encoding process, using a different random number generator users coding, to give users different from the other, independent of the Tanner graph, so that each user can ensure that the signal is not relevant , providing each user signal separation feasibility of the decoding;

[0101] 实施例2:当编码采用Raptor Code时(它是由外码部分的高码率LDPC Code以及内码部分的LT Code级联组成的),按照如下方式进行编码: [0101] Example 2: When coding using Raptor Code (which is part of the high rate LDPC Code outer code and an inner code concatenated LT Code portion composed), is encoded as follows:

[0102]编码第一步,按照 Linear-Time PEG Encoding 算法(见“Regular andIrregularProgressive Edge-Growth Tanner Graphs,,,IEEE Transactions OnInformationTheory, Vol.51,N0.1, January 2005),对m = 1024 个消息数据包进行LDPC 编码,生成LDPC Code的Tanner图,进而得到η = 1072个LDPC Code的编码包。用tk(l)表示LDPC Code的编码包,其中I为编码包的编号(I = 1,2,...,1072),下标k为用户的编号(k = 1,2,...,K)。 [0102] The first step in coding, according Linear-Time PEG Encoding algorithm (see "Regular andIrregularProgressive Edge-Growth Tanner Graphs ,,, IEEE Transactions OnInformationTheory, Vol.51, N0.1, January 2005), for m = 1024 messages packet LDPC encoding, LDPC Code Tanner graph generated, and thus obtained η = 1072 th LDPC code packet Code. Code LDPC code packet represented by tk (l), where I is the number of code packet (I = 1,2 , ..., 1072), the subscript k is the number of users (k = 1,2, ..., K).

[0103] Raptor Code外码部分的LDPC Code的Tanner图如图3所示,图中有两类节点,圆圈表示变量节点(variable node),共有η = 1072个,记作Vu, Vkj2,..., Vk,n,分别对应LDPC Code 的编码包tk(l),tk(2),..., tk(η);方框表示校验节点(check node),共有n_m=1072-1024 = 48个,分别记作C' ka, Ci k,2,...,C' k,n_m,其与变量节点的连接方式由Linear-Time PEG Encoding算法生成,与每一个校验节点相连的各节点的校验和为O。 [0103] LDPC Code Tanner graph Raptor Code outer code section as shown, in FIG. 3 has two types of nodes, variable nodes circles represent (variable node), η = 1072 total th, denoted as Vu, Vkj2, .. ., Vk, n, respectively corresponding to the code packet LDPC Code tk (l), tk (2), ..., tk (η); block represents a check node (check node), a total of n_m = 1072-1024 = 48, are designated as C 'ka, Ci k, 2, ..., C' k, n_m, its connection to the variable nodes is generated by Linear-Time PEG Encoding algorithm, check node connected to each of the respective node checksum is O. 我们定义Tanner图中,连接到某个节点的边的总数为这个节点的度数。 We define Tanner graph, the total number of edges connected to a node is the degree of this node. 我们固定LDPC Code的变量节点中,前5个节点的度数为1,其余节点的度数为4,按照Linear-Time PEG Encoding算法为各变量节点选择与校验节点的连接关系,构成Tanner图。 We fixed LDPC Code variable node, the first five degrees of a node, the remaining nodes of degree 4. The Linear-Time PEG Encoding Algorithm relation to each variable nodes connecting to the check node selection, configuration Tanner graph. 由该算法得到的Tanner图所对应的校验矩阵H,具有如下性质:H = [Hp,Hd],右边部分的Hd是一个48 X 1024矩阵,左边部分的Hp是一个48X48上三角矩阵: Obtained by the algorithm Tanner graph corresponding to the parity check matrix H, has the following properties: H = [Hp, Hd], Hd right part is a 48 X 1024 matrix, Hp left part is a 48X48 upper triangular matrix:

Figure CN101695016BD00151

[0105] 则LDPC Code的编码包的值可以由下式求得: [0105] LDPC Code value of the coded packet may be represented by the following formula:

Figure CN101695016BD00152

[0107] 可见,由该算法得到的LDPC Code是系统码,其1072个编码包中,后1024个就是 [0107] visible, obtained by the algorithm LDPC Code is a systematic code, which code packet 1072, the post 1024 is

消息数据包。 Message data packet.

[0108] 编码第二步,对η = 1072个LDPC Code的编码包进行LT编码,生成LT Code的Tanner图,并得到源源不断生成的LT Code的编码包。 [0108] Step encoding, for η = 1072 th packets encoded LDPC Code encoding LT, LT generation Code Tanner graph, and the obtained LT Code steady stream generated code packet. 用vk(S)表示LT Code的编码包(也就是整个Raptor Code的编码包),其中s为编码包的编号(s = 1,2,...),下标k为用户的编号(k= 1,2,...,K),编码方法为:要产生LT Code编码包Vk (S),首先按照表I所示的度数分布Ω (X),用随机数生成器为其产生度数Clegk(S);然后用随机数生成器产生一个1072维二元域向量{<^}(/ = 1,2...,1072),元素Qk的取值为“O”或者“ ,其中元素“ ! LT Code indicates a code packet vk (S) (i.e. the entire encoded packet Raptor Code), wherein the number (s = 1,2, ...) s encoding packet, k is a user index number (k = 1,2, ..., K), the encoding method: encoding packets to generate LT Code Vk (S), according to the first degree distribution shown in table I Ω (X), for generating a random number generator with the degree Clegk (S); 1072 and then generates a field of two-dimensional vector using a random number generator {<^} (/ = 1,2, ..., 1072), the element value of Qk is "O" or ", where the elements "! ”的个数为degk(S)。元素Gfc为“I”表示对应的编号为I的LDPC Code编码包tk(l)被选中,将这些被选中的LDPC Code编码包按比特作模2求和,即得到LT Code的编码包的值: "The number of degk (S). Gfc element of" I "indicates that a corresponding number of LDPC Code I code packet tk (l) is selected, the selected code packet LDPC Code bitwise modulo 2 summation , i.e., to obtain a code packet LT Code value:

Figure CN101695016BD00153

[0110] Raptor Code内码部分的LT Code的Tanner图如图4所示。 [0110] LT Code portion of the inner code Raptor Code Tanner graph shown in Figure 4. 图中有两类节点,圆圈表示变量节点(variable node),变量节点又分为两类,上面一行为信息节点(informationnode),共有η = 1072个,记作V1^1, Vkj2,...,Vk,n,*别对应LT Code的数据包(此时即为LDPC Code 的编码包tk(l),tk(2),..., tk(η)),下面一行为编码节点(parity node),记作Pk,i,Pu,...» Pkjs»...,分别对应LT Code 的编码包vk(l),vk(2),..., vk(s),...;方框表示校验节点(check node),分别记作C1^1, Ck,2,..., Ck,s,..,与每一个校验节点相连的各节点的校验和为O。 There are two types of nodes in FIG circle indicates a variable node (variable node), the variable nodes divided into two categories, top row information node (informationnode), η = 1072 total th, denoted V1 ^ 1, Vkj2, ... , Vk, n, * respectively corresponding packet LT Code (LDPC Code is the case of code packet tk (l), tk (2), ..., tk (η)), following a coding node behavior (Parity node), denoted as Pk, i, Pu, ... »Pkjs» ..., LT Code corresponding to each code packet vk (l), vk (2), ..., vk (s), ... ; block represents a check node (check node), respectively referred to as C1 ^ 1, Ck, 2, ..., Ck, s, .., each node and each check node a is connected to the checksum O . 因此,在编码过程中用随机数生成器为每一个LT Code的编码包Vk(S)选择degk(S)个LDPC Code的编码包作模2求和,在Tanner图中就体现为为校验节点Ck, s选择degk(s)个信息节点相连。 Thus, each code packet LT Code Vk (S) select degk (S) in the encoding process by the random number generator is a code packet LDPC Code modulo 2 summation in the Tanner graph is reflected to check node Ck, s selection degk (s) is connected to the node number information. 而校验节点Ck,s与编码节点Pk,s的连接关系是固定的,Ck,s总是与Pk,s——对应的相连。 Ck is connected to check node relationship, s Pk of encoding node, s is fixed, s s-- connected to the corresponding Ck, always Pk,. 由于LT Code是一种Rateless编码,其编码包个数随着编码过程源源不断的增加,所以每产生一个新的LT Code编码包Vk(S),图中就会增加一个新的校验节点ck, s和一个新的编码节点Pk, s,随着编码包源源不断的增多,Tanner图会越来越大。 Since LT Code is a Rateless coding, which encodes the packet number increases with a steady stream of the encoding process, so each new LT Code to generate a coded packet Vk (S), the figure will increase to a new check node ck , s, and a new coding node Pk, s, with a steady stream of code packet increases, Tanner FIG growing. 整个Raptor Code的Tanner图如图5所不,它是由LDPC Code的Tanner图和LT Code的Tanner图级联合并组成的。 Raptor Code entire Tanner graph shown in Figure 5 does, it is combined by a Tanner graph of LDPC Code and a Tanner graph composed of cascaded LT Code.

[0111] 各用户独立完成自己的Raptor Code编码过程,编码时使用不同于其他用户的随机数生成器,以得到与其他用户不同的、相互独立的Tanner图,这样可以保证各用户信号的不相关性,为译码时各用户的信号分离提供可行性; [0111] each user to independently complete their Raptor Code encoding process, using a different random number generator users coding, to give users different from the other, independent of the Tanner graph, so that each user can ensure that the signal is not relevant , providing each user signal separation feasibility of the decoding;

[0112] 2)利用映射器_k,进行由编码包数据比特到编码包传输符号的映射; [0112] 2) using the mapper _k, the bit of the code packet transmission symbols mapped by the encoded data packet;

[0113] 将由编码器_k得到的编码包Vk(S)送入映射器_k,映射方式可采用普通的线性调制方式(如BPSK、QPSK等),完成由编码包数据比特到编码包传输符号的映射:Vk(S) — Wk(S),其中S为编码包的编号(S = 1,2,...),下标k为用户的编号(k = 1,2,...,K); [0113] code packets Vk (S) obtained by the encoder into _k _k mapper, mapping mode can be an ordinary linear modulation scheme (e.g., BPSK, QPSK, etc.), done by the coded bits to encode the packet data packet transmission symbol mapping: Vk (S) - Wk (S), where S is the number of code packet (S = 1,2, ...), the subscript k is the number of users (k = 1,2, ... , K);

[0114] 实施例3:当映射方式为BPSK时,Vk (S)中每一个比特映射为wk (S)中的一个符号,映射方式为:"O —+1,1 —-1",得到经过映射的编码包wk(s)。 [0114] Example 3: When the mapping mode is BPSK, Vk (S) in each bit is mapped as a symbol wk (S), mapping mode is: "O - + 1,1 --1", to give the encoded packet mapping wk (s).

[0115] 实施例4:当映射方式为QPSK时,Vk (S)中每两个比特映射为wk (S)中的一个符号,映射方式为:"00 —+l+j,01 —+lj,10 —-l+j,ll —-lj",得到经过映射的编码包 [0115] Example 4: When the mapping mode is QPSK, Vk (S) for every two bits are mapped to one symbol of wk (S), mapping mode is: "00 - + l + j, 01 - + lj , 10 --l + j, ll --lj ", obtained through the mapping of code packet

Wk(S)。 Wk (S).

[0116] 3)利用接入控制器_k,进行对编码包的发送控制; [0116] 3) using the access controller _k, transmission control code packet;

[0117] 将由映射器-k得到的经过映射的编码包Wk (S)送入接入控制器_k,在任一个时隙j (j = I,2,...),用户k以概率Pk顺序将Wk (S)接入信道发送:用Xk (j)表示用户k在时隙j经信道发送的符号,如果决定在当前时隙j将编码包Wk(S)接入信道,则在编码包Wk(S)包头增加K个比特的用户标示信息,其中第k位置1,其余各位置0,组成发送编码包Wk' (S),令xk(j) =Wk' (s),在下一个时隙判断是否将wk(s+l)接入信道;否则令xk(j) =0,下一个时隙继续判断是否将Wk (S)接入信道; [0117] obtained by the mapper -k encoded packet Wk (S) is mapped into the access controller _k, at any one time slot j (j = I, 2, ...), a probability Pk user k sequentially Wk (S) transmits the access channel: a user indicates a symbol j in a slot k transmitted via a channel with Xk is (j), j if the decision in the current time slot code packet Wk (S) access channel, then the coding package Wk (S) header increased K bits of user designation information, wherein the k-th position 1, the rest position 0, the composition of the transmission code packet Wk '(S), so that xk (j) = Wk' (s), the next slot determines whether wk (s + l) access channel; else let xk (j) = 0, the next time slot continues to determine whether wk (S) access channel;

[0118] 由于采用的是Rateless编码方式,所以经过Rateless编码及映射后的序列=Iwk(I) ,Wk (2), wk(s),...}是源源不断产生的,于是经信道发送的序列= Ixk(I),xk(2),...,xk(j),...}也是源源不断的,长度并不是固定的,Xk的每一个长度都对应相应的一个码率; [0118] As a result of Rateless encoding, so after the sequence coding and mapping Rateless = Iwk (I), Wk (2), wk (s), ...} is the continuing flow, then transmitted via the channel sequences = Ixk (I), xk (2), ..., xk (j), ...} is a steady stream of length is not fixed, the length of each of Xk corresponds to a respective code rate;

[0119] 每个用户的发送机根据以上规则,源源不断的产生编码包并接入信道,直至接收端告知它停止发送。 [0119] each user transmitter according to the above rules, a steady stream of code packets and generate an access channel, to inform the receiving terminal until it stops to send.

[0120] 译码方法如下: [0120] The decoding method is as follows:

[0121] 接收机接收到来自信道的,源源不断的,各个用户相互混叠且加上了噪声的编码包,各用户的信号分离及译码同时进行,对于用户k(k = 1,2,...,K),其判决译码器-k采用和编码器_k相同的随机数生成器,所以可以准确的重构该码的Tanner图,按照如下步骤进行信号分离和译码: [0121] The receiver receives the incoming from the channel, a steady stream of each user and each added aliasing noise code packet, each user's signal separating and decoding the same time, for user k (k = 1,2, ..., K), which decision decoder and the encoder _k -k using the same random number generator, it is possible to accurately reconstruct the Tanner graph of the code, a demultiplexing and decoding the following steps:

[0122] I)接收机首先接收到N = 1024个来自信道的混叠编码包; [0122] I) receiver first receives N = 1024 channels are from aliasing code packet;

[0123] 2)接收机再接收ΛΝ = 256个混叠编码包,令N = N+Λ N,此时的码率为 [0123] 2) The receiver then receives the alias bands ΛΝ = 256 code packet, so that N = N + Λ N, at this time the rate of

Figure CN101695016BD00171

[0125] 3)将接收到的编码包送入解映射及译码软信息估计器_k,采用基于无速率码的多用户随机接入系统的译码软信息估计方法,在当前码率R下进行运算,利用除了判决译码器_k之外其余各用户的判决译码器的输出软信息(初始化时为O),更新估计软信息; [0125] 3) the received coded packet into the soft demapping and decoding information _K estimator, a random access decoding the soft information estimation method based on multi-user systems without rate code in the current code rate R under calculates, in addition to using _k decision decoder outputs a soft decision information of each user to rest decoder (initialization is O), soft information updating estimates;

[0126] 4)将由解映射及译码软信息估计器_k更新得到的估计软信息作为判决译码器_k的输入,在重构的当前码率R下的Tanner图上运行BP(Belief-Propagation)译码算法,完成一轮迭代译码运算,并更新判决译码器_k的输出判决结果信息和输出软信息; [0126] 4) soft demapping and decoding information obtained by updating _k estimator estimates soft decision information as inputs _k decoder, operating on the Tanner graph in the reconstructed current code rate R BP (Belief -Propagation) decoding algorithm, an iterative decoding operation is completed, and the update result information and outputs a soft decision information decoder output decision _k;

[0127] 5)利用判决译码器-k的输出判决结果信息判断译码结果是否满足Tanner图中校验节点所限制的校验关系,或者迭代次数已经达到所限定的最大次数(设为150次),如果满足上述两个条件之一,则转入步骤6); The maximum number of outputs of the decision [0127] 5) -k decoder using the decision result information determines the decoding result meets the limit check the relationship between check nodes in the Tanner graph, the number of iterations has been reached or as defined in (set to 150 s), if one of the above two conditions satisfied, the process proceeds to step 6);

[0128] 否则转入步骤3); [0128] Otherwise, go to step 3);

[0129] 6)利用各个包内的循环冗余校验码判断数据包是否都译码正确,如果都正确,转入步骤7);否则转入步骤2); [0129] 6) using a cyclic redundancy check code in each packet determines whether the decoded data packets are correct, if correct, go to step 7); otherwise, go to step 2);

[0130] 7)译码结束,接收机发送一个信号告知用户k的发送机停止发送。 [0130] 7) the end of decoding, the receiver sends a signal to inform the user k transmitter stops transmitting.

[0131] 由以上对译码过程的描述可知,当用户发现接收到的混叠编码包不足以正确译码时,接收机需要再接收256个混叠编码包,进行新一轮的迭代译码。 [0131] apparent from the above description of the decoding process, when the user finds that the received code packets insufficient aliasing correctly decoded, the receiver need to aliasing received code packet 256, a new round of iterative decoding . 当接收机收到N个编码包时,对应的码率为: When the receiver receives the N encoding packets, the corresponding rate is:

Figure CN101695016BD00172

[0133] 为了表示方便,我们用码率的倒数IT1来刻画码率的变化: [0133] For ease of presentation, we use the reciprocal of the rate of IT1 to characterize the rate of change:

Figure CN101695016BD00173

[0135] 每次多接收Λ N个编码包后,码率变化为Λ IT1: After [0135] receiving Λ N each multiple coded packets, bit rate change Λ IT1:

Figure CN101695016BD00174

[0137] 此处ΛΝ为256,所以Λ IT1为0.25。 [0137] Here ΛΝ 256, so Λ IT1 is 0.25. 即是说,各用户以Λ IT1 = 0.25为步进,在不同的码率下运行迭代译码,直至译码成功,发送一个信号告知发送机停止发送。 That is, each user stepping Λ IT1 = 0.25, iterative decoding run at different bit rates, until the decoding is successful, transmits a signal informing the transmitter to stop sending.

[0138] 基于无速率码的多用户随机接入系统的译码软信息估计方法如下: [0138] Soft information estimating method of decoding a multi-user system without the random access is based on the rate code:

[0139] 我们设接收机接收到来自信道的,源源不断的,各用户混叠且加上了噪声的编码包序列为I = {y (I), y (2),..., y (j),...}: [0139] We set the receiver to receive incoming from the channel, a steady stream of each user and aliasing noise added packet sequence coding for I = {y (I), y (2), ..., y ( j), ...}:

Figure CN101695016BD00175

[0141] 其中,j为时隙标号,下标i为用户的编号(i = 1,2,...K), Xi = (Xi(I),Xi(2),...,Xi(j),...}为第i个用户经信道发送的源源不断的序列,h为信道参数,η ={η(1), η(2)n(j), }为均值为O,方差为σ 2的白高斯噪声序列; [0141] where, j is a slot indices, i denotes the number of users (i = 1,2, ... K), Xi = (Xi (I), Xi (2), ..., Xi ( j), ...} is a sequence of a steady stream of the i th user transmitted via the channel, h is the channel parameters, η = {η (1), η (2) n (j),} is the mean value is O, variance is a sequence of white Gaussian noise σ 2;

[0142] 在接收机,我们根据任一时隙j接收到的编码包包头的用户标示信息,判断出该时隙各用户的信道接入状况(对包头K个比特作硬判决,第k(k= 1,2,...,K)位比特判决结果为I表示第k个用户接入了信道,为O表示第k个用户没有接入信道),然后去掉用户标示信息;用Jk表示用户k(k = 1,2,..., K)的编码包接入时隙的集合: [0142] At the receiver, we receive a time slot according to any j code packet header user designation information, it is determined that the channel status of each user access to the slots (K bits of the header as a hard decision, the k (k = 1,2, ..., K) bits for the decision result I represents the k-th user access channel, is O represents the k-th user has no access channel), and then remove the user designation information; Jk represented by user k (k = 1,2, ..., K) of the set of code packet access slot:

[0143] Jk = {j xk(j)关O, j = 1,2,...} = {Jk(l) , Jk(2) ,..., Jk(qk),...} [0143] Jk = {j xk (j) Off O, j = 1,2, ...} = {Jk (l), Jk (2), ..., Jk (qk), ...}

[0144] 其中qk为集合Jk中元素的编号(qk= 1,2,...),下标k为用户的编号(k = 1, [0144] where qk is the number of elements in the set Jk (qk = 1,2, ...), the subscript k is the number of users (k = 1,

2,..., K); 2, ..., K);

[0145] 对于每一个用户,我们要在接收机接收到不同长度的编码包序列I时,即在不同的码率R下,计算其解映射及译码软信息估计器的输出估计软信息,对用户k,设接收机已经接收了N个编码包ί = {y (I), y (2),..., y (N)},则当前的码率为R = m/N = 1024/N ; When [0145] For each user, we have to receive different lengths of coding sequence of packets at the receiver I, i.e. at a different code rate R, which is calculated demapping and outputs the decoded soft information estimator estimates soft information, for user k, the receiver has received a set of N code packet ί = {y (I), y (2), ..., y (N)}, then the current code rate is R = m / N = 1024 / N;

[0146] 对于其接入时隙集合Jk中的每一个时隙Jk(qk),其接收到的混叠编码包y (Jk(Qk)),可以写作: [0146] for which the access slot set for each time slot Jk (qk) Jk in which the received code packets aliasing y (Jk (Qk)), can be written as:

Figure CN101695016BD00181

[0149] 其中4k(Jk(qk))为在时隙Jk(qk),非零的其他用户信号和高斯白噪声之和,我们将其称为合并噪声且近似视其为高斯随机变量,均值记为E[ 4k(Jk(qk))],方差记为Var [ ζ k (Jk (qk))],于是可以将接收编码包y (Jk (qk))也视作符合高斯特性: [0149] wherein 4k (Jk (qk)) as slot Jk (qk), other user signals and white Gaussian noise of zero sum, we call them as combined noise and approximately Gaussian random variable with mean referred to as E [4k (Jk (qk))], referred to as the variance Var [ζ k (Jk (qk))], then the packet may be received encoded y (Jk (qk)) is also regarded as a Gaussian characteristics:

Figure CN101695016BD00182

[0153] 在解映射及译码软信息估计器_k中,首先按照所选用的映射方式所对应的均值运算规则1^和方差运算规则rvm,由其余各用户编码包的比特log似然比软信息,算出其余各用户编码包的映射符号的均值和方差;然后按照所选用的映射方式所对应的解映射规则F,由接收到的混叠编码包和已经算出的其余各用户编码包的映射符号的均值和方差,根据接收编码包符合的高斯特性,估计出用户k编码包的比特log似然比软信息。 [0153] In the soft demapping and decoding information estimator _k, a first embodiment according to the selected mapping rules corresponding to the arithmetic mean and variance 1 ^ RVM operational rule, the remaining bits of the encoded packet for each user log likelihood ratio soft information, calculates the mean and variance of the remaining symbol mapping for each user code packet; then, according to a demapping rule selection of mapping mode corresponding F., by the received remaining user aliasing code packet and already calculated code packet mean and variance of the symbols are mapped, according to a Gaussian characteristic of the received code packets compliant, estimated user k code packets bit log likelihood ratio of the soft information.

[0154] 在第a次迭代时,按照“估计软信息更新表达式” [0154] When a first iteration, according to "soft information update estimated expression"

Figure CN101695016BD00183

[0161] 更新估计软信息,式中LLRka (v(qk))为用户k第a次迭代译码所需的由解映射及译码软信息估计器_k估计出的第qk个编码包的比特log似然比软信息矢量,L^1 (V (¾))为用户i第a-Ι次迭代译码后的第qi个编码包的比特log似然比软信息矢量(初始化a= I时, [0161] updating estimates soft information, wherein LLRka (v (qk)) necessary for decoding iteration of a user k by the soft demapping and decoding information estimator _k estimated first encoded packet qk bit soft log likelihood ratio information vector, L ^ 1 (V (¾)) is the bit i of a user after log a-Ι qi iterative decoding of encoded packet soft log likelihood ratio information vector (initialization of a = i Time,

Figure CN101695016BD00191

[0162] 如果映射方式采用BPSK,将具体的均值运算规则Γ E,BPSK,方差运算规则Γ Var>BPSK以及解映射规则Fbpsk代入“估计软信息更新表达式”,可以得到其具体的表达形式: [0162] If the mapping mode using BPSK, a specific mean arithmetic rule Γ E, BPSK, variance calculation rules Γ Var> BPSK and demapping rule Fbpsk substitutes "estimated soft information updating expression" can be obtained by the specific expression of the form:

Figure CN101695016BD00192

[0164] (qk == 1,2,...|jk|c = 1,2,...,128) [0164] (qk == 1,2, ... | jk | c = 1,2, ..., 128)

[0165] 其中,y(Jk(qk))(c)表示在时隙Jk(qk)接收到的混叠编码包y中的第C个符号,LLRka (V (qk) (c))为用户k第a次迭代译码所需的由解映射及译码软信息估计器_k估计出的第qk个编码包的第c个比特的log似然比软信息,L^1 (V (¾) (c))为用户i第a-Ι次迭代译码后的第Qi个编码包的第c个比特的log似然比软信息。 [0165] where, y (Jk (qk)) (c) represented by aliasing in a time slot code packet y Jk (qk) of the received C symbol, LLRka (V (qk) (c)) for the user c-th bits estimated by the demapping and decoding the first soft information estimator _k qk encoded packets of log k times a desired ratio of soft iterative decoding likelihood information, L ^ 1 (V (¾ ) (c)) is a log of the c-th bit Qi encoded packet after a first user i, a-Ι iterations than the soft decoding likelihood information.

[0166] 如果映射方式采用QPSK,则将具体的均值运算规则Γ E, QPSK,方差运算规则Fvm, QPSK以及解映射规则Fqpsk代入“估计软信息更新表达式”,可以得到其具体的表达形式: [0166] If the mapping mode using QPSK, then the mean specific arithmetic rule Γ E, QPSK, variance calculation rules Fvm, QPSK demapping rule Fqpsk and substituting "soft information estimation updating expression", which can be specific expressions:

Figure CN101695016BD00193

[0169] (qk = 1,2,...Jk | c = 1, 2,..., 64) [0169] (qk = 1,2, ... Jk | c = 1, 2, ..., 64)

[0170] 其中,y(Jk(qk))(c)表示在时隙Jk(qk)接收到的混叠编码包y中的第C个符号,LLRka (V (qk) (2c_d)、LLRka(v(qk) (2c))为用户k第a次迭代译码所需的由解映射及译码软信息估计器_k估计出的第qk个编码包的奇数位和偶数位比特的log似然比软信息,L^1 (V (¾)tee-!))、L^1 (V (¾) (2c))为用户i第a-ι次迭代译码后的第qi个编码包的奇数位和偶数位比特的log似然比软信息,Re[.]表示取实部运算,Im[.]表示取虚部运算。 [0170] where, y (Jk (qk)) (c) represented by aliasing in a time slot code packet y Jk (qk) of the received C symbol, LLRka (V (qk) (2c_d), LLRka ( even bit and odd bit bit log v (qk) (2c)) necessary for decoding iteration of a user k estimated by the demapping and decoding the first soft information estimator _k qk encoded packet like soft information likelihood ratio, L ^ 1 (V (¾) tee -!)), L ^ 1 (V (¾) (2c)) i for the user after the first a-ι iterative decoding of encoded packets qi odd bits and even bits in the soft log likelihood ratio information, Re [.] represents the calculation taking the real part, Im [.] represents the calculation taking the imaginary part.

[0171] 然后将估计软信息矢量LLRka(v(qk))作为判决译码器_k的输入软信息矢量Lkin'a(qk),即令 [0171] Then the estimated information vector soft LLRka (v (qk)) as an input soft decision information decoder _k vector Lkin'a (qk), and even if

Figure CN101695016BD00194

送入判决译码器_k进行第a次的迭代译码;其余各用户也按此同样操作,各用户译码同时进行;完成第a次迭代后,对于用户k,得到其判决译码器_k的输出软信息矢量 _K into decision decoder of the iterative decoding times a; Click to the remaining users in the same manner, simultaneously decoding each user; after a completion of the first iteration, for user k, which is obtained decision decoder the soft information output vector _k

Figure CN101695016BD00195

其余用户也按此同样操作,接着将相应的值代入“估计软信息更新表达式”,开始新一次(第a+Ι次)的迭代,以此类推,直至判决译码器_k的译码结果满足Tanner图中校验节点所限制的校验关系或者迭代次数达到所限定的最大次数; Click to the same manner as the rest of the user, then the appropriate values ​​are substituted into "updated soft information estimation expression" a new (first a + Ι th) iteration start, and so on, until the decision decoded by decoder _k results meet the maximum number of the Tanner graph the relationship between the check or check node restricted number of iterations reaches the defined;

[0172] 这样可以完成码率R = m/N = 1024/N下的软信息估计,由于编码方式的Rateless属性,其编码包序列长度N是不断变化的,我们可以在不同的接收编码包长度下,即各个码率下,运行各自对应的运算,从而完成各个码率下的软信息估计,进而完成信号分离和译码。 [0172] This achieves a code rate R = m / N = soft information estimated at 1024 / N, since the properties Rateless encoding which encodes the packet sequence length N is constantly changing, we can receive a different code packet length under, i.e. at each code rate, each corresponding arithmetic operation, thereby completing the soft information at each bit rate estimation, and then complete the demultiplexing and decoding.

[0173]图6和图7,是米用Raptor Code 的RMA系统和米用Zigzag Code (见“Zigzagcodesand concatenated zigzag codes,,,IEEE Trans.1nform.Theory special issue oncodeson graphs,vol.,IT-47, n0.2,pp.,800-807,Feb.2001.)的IDMA 系统,在系统用户数K =2和K = 4时的性能比较图。可以看到,釆用Raptor Code的RMA系统的性能要优于釆用Zigzag Code 的IDMA 系统。 [0173] FIGS. 6 and 7, m is a Raptor Code and the system meters with RMA Zigzag Code (see "Zigzagcodesand concatenated zigzag codes ,,, IEEE Trans.1nform.Theory special issue oncodeson graphs, vol., IT-47, n0.2, pp., 800-807, Feb.2001.) of the IDMA system, can be seen in the number of system users K = 2 and K = 4 of FIG performance comparison, preclude performance of the RMA with Raptor Code system superior to preclude the Zigzag Code IDMA systems.

Claims (4)

1.一种基于无速率码的多用户随机接入系统,其特征在于,它主要由发送端和接收端构成;其中,发送端由K个单路输入、单路输出的发送机并行接入信道组成,接收端由一个单路输入、K路输出的接收机组成;每个发送机由编码器,映射器和接入控制器依次串行连接组成;接收机在内部分为并行的K路,每一路由解映射及译码软信息估计器和判决译码器串行连接而成,其中,K为任意正整数; 编码器-k,用于将用户k的消息数据包编为源源不断产生的无速率码编码包,其输入端接外部消息数据包的数据流,其输出端接至映射器_k的输入端; 映射器_k,用于完成由编码包数据比特到编码包传输符号的映射,用通常的线性调制映射器来实现,其输入端接编码器_k的输出端,其输出端接至接入控制器_k的输入端; 接入控制器-k,主要完成对编码包的发送控制,即 A random access multi-user systems based on non-rate code, characterized in that it mainly consists of the sending end and a receiving end; wherein the transmission side of K single-input, single-output transmitter parallel access channel composed of the receiving end by a single input, K-output receiver; each transmitter by the encoder and the mapper and the access controller connected to form a serial sequence; a receiver within the passage into K parallel each routing demapping and decoding the soft decision decoding information estimator and connected in serial, wherein, K is any positive integer; encoder -k, k for the user of the message packet is a steady stream of compiled no code encoding packet generation rate, the external input data stream termination message data packet, which is output to an input end of the mapper _k; _k mapper, for performing packet transmission bit coded data into a code packet symbol mapping, using conventional linear modulation mapper to achieve, with the input connected to the output of the encoder _k, its output end to the input end of the access controller _k; access controller -k, mainly to complete transmission control code packet, i.e., 按事先确定的概率随机决定是否将当前编码包在当前时隙中接入信道进行发送,其输入端接映射器_k的输出端,其输出端接至信道; 解映射及译码软信息估计器_k,用于根据接收到的来自信道的混叠编码包完成各用户信号分离,以及通过解映射完成对用户k的编码包比特Log似然比软信息的估计,其输入端接接收机的来自于信道的输入以及除了判决译码器_k之外其余各判决译码器的软信息输出端,其输出端接至判决译码器_k的输入端; 判决译码器_k,用于完成对用户k编码包的译码,其输入端接解映射及译码软信息估计器-k的输出端,其判决结果输出端输出译码结果,作为接收机的一路输出,其软信息输出端接至除了解映射及译码软信息估计器_k之外的其余各解映射及译码软信息估计器的输入端; k = 1,2,…,K。 Probabilistically determined in advance to decide whether the current random code packet transmitted in the current slot access channel, input and output terminal mapper _k end, the output end to the channel; soft demapping and decoding information estimation _K device, for performing signal separation for each user according to the received code packets aliasing from the channel, and by the completion code packet demapping user k bit Log likelihood ratio estimation soft information, the receiver input terminal input from the channel and in addition to the rest of the soft decision information decoder _k output of each decision decoder, the output end to the input terminal of the decision decoder _k; _k decision decoder, for performing decoding of user k code packets, the input and output end demapping and decoding estimator -k soft information, the decision result output terminal outputting the decoding result, one output of the receiver as its soft output termination information to the rest of the demapping and decoding the soft information in addition to the input of the estimator demapping and decoding the soft information outside estimator _k; k = 1,2, ..., K.
2.—种权利要求1所述接入系统的编码方法,在发送端按照编码方法完成各用户的编码接入,将各用户的编码包接入信道进行发送,其特征在于,该编码方法如下:设每个发送机均需要发送m个消息数据包,每个消息数据包由b个数据比特组成,其中包括一个循环冗余校验码,用于判决译码器判断译码是否成功,用dk(i)表示消息数据包,其中,i为消息数据包的编号,i = 1,2,...,m ;下标k为用户的编号,k = 1,2,...,K ;考虑其中的第k个用户,k = 1,2,...,K ;按照如下步骤进行编码接入: (1)利用编码器_k进行编码:将消息数据包dk(i)送入编码器_k,通过无速率编码方式,得到源源不断产生的编码包序列以及该码的Tanner图,用vk(s)表示编码所得的编码包,其中s为编码包的编号,s = 1,2,...;下标k为用户的编号,k = 1,2,...,K;各用户独立完成自己的编码过程,编码时使用 The method of claim 1 encoding 2.- access system as claimed in claim species, the access of each user to complete the encoding method according to the coding at the transmitting end, each user's access code packet transmission channel, characterized in that the encoding method is as follows : each transmitter set of m require sending message data packet, each message packet consists of b bits of data, which includes a cyclic redundancy check code, for deciding whether the decoder determines the decoding is successful, with DK (i) indicates that the message packet, where i is the number of message packets, i = 1,2, ..., m; the subscript k is the number of users, k = 1,2, ..., K ; consider the case where the k-th user, k = 1,2, ..., K; encoded access the following steps: (1) encoded by the encoder _K: the message data packet dk (i) into _K encoder, by way of non-rate coding, the coding sequence of packets obtained and a Tanner graph of the code generated by a steady stream, an encoding VK obtained by encoding a packet (s), where s is the number of code packets, s = 1, 2, ...; the index k is the number of users, k = 1,2, ..., K; each independently users own coding process, using the coding 同于其他用户的随机数生成器,以得到与其他用户不同的、相互独立的Tanner图,这样可以保证各用户信号的不相关性,为译码时各用户的信号分离提供可行性; (2)利用映射器_k,进行由编码包数据比特到编码包传输符号的映射:将由编码器_k得到的编码包Vk(s)送入映射器_k,映射方式采用普通的线性调制方式,完成由编码包数据比特到编码包传输符号的映射:Vk (s) — wk (s),其中s为编码包的编号,S= 1,2,...;下标k为用户的编号,k= 1,2,...,K; (3)利用接入控制器_k,进行对编码包的发送控制:将由映射器_k得到的经过映射的编码包Wk(S)送入接入控制器_k,在任一个时隙j,j = 1,2,...;用户k以概率pk顺序将Wk(S)接入信道发送:用xk(j)表示用户k在时隙j经信道发送的符号,如果决定在当前时隙j将编码包Wk(S)接入信道,则在编码包Wk(S)包头增加K个比特的用户标示信息,其 With other users of a random number generator to obtain different from other users, independent of the Tanner graph, which can not guarantee the relevance of each user signal, the feasibility of providing a signal when the coded user separated; (2 ) _k using a mapper, mapping of bits to be encoded by the encoding symbols transmitted packet data packet: encoding packets Vk (s) obtained by the encoder into _k _k mapper, mapping mode of the ordinary linear modulation scheme, complete mapping of bits to symbols encoded by the encoder packet transmission packet data: Vk (s) - wk (s), where s is the number of code packets, s = 1,2, ...; the subscript k is the number of users, k = 1,2, ..., K; (3) using the access controller _k, transmission control code packet: _k obtained by the mapper encoded packet Wk (S) mapped into contact the controller _k, at any one time slot j, j = 1,2, ...; k user transmits with a probability pk order Wk (S) access channel: represents user k in time slot j with XK (j) channel symbols are transmitted, if the decision in the current time slot j code packet Wk (S) access channel, then the code packet Wk (S) header bits K to increase user designation information, which 第k位置1,其余各位置O,组成发送编码包Wk' (S),令Xk (j) =Wk' (S),在下一个时隙判断是否将wk(s+1)接入信道;否则令xk(j) = O,下一个时隙继续判断是否将Wk(S)接入信道;由于采用的是无速率编码方式,所以经过编码及映射后的序列Ik= Iwk(I),Wk (2),...,Wk (S),...}是源源不断产生的,于是经信道发送的序列= Ixk (I),xk (2),...,xk(j),...}也是源源不断的,长度并不是固定的,Ik的每一个长度都对应相应的一个码率;每个用户的发送机根据以上规则,源源不断的产生编码包并接入信道,直至接收端告知它停止发送。 A k-th position, the rest position O, the composition of the transmission code packet Wk '(S), so that Xk (j) = Wk' (S), determines whether the next time slot wk (s + 1) access channel; otherwise order xk (j) = O, the next time slot continues to determine whether Wk (S) access channel; encoding rate because it is not used, so after the sequence coding and mapping Ik = Iwk (I), Wk ( 2), ..., Wk (S), ...} is generated in a steady stream, whereupon the sequence is transmitted via the channel letter = Ixk (I), xk (2), ..., xk (j), .. .} is a steady stream of length is not fixed, the length of each of Ik corresponds to a respective code rate; a transmitter for each user according to the above rules, generating a steady stream of code packets and the access channel until receiving end tell it to stop sending.
3.—种权利要求1所述接入系统的译码方法,在接收端根据接收到的混叠编码包,完成各用户编码包的检测分离和译码;该译码方法如下:接收机接收到来自信道的,源源不断的,各个用户相互混叠且加上了噪声的编码包,各用户的信号分离及译码同时进行;对于用户k,k= 1,2,...,K,其判决译码器_k采用和编码器_k相同的随机数生成器,所以可以准确的重构该码的Tanner图,按照如下步骤进行信号分离和译码: (A)接收机首先接收到N= m个来自信道的混叠编码包; (B)接收机再接收ΔΝ个混叠编码包,令N = Ν+ΛΝ,此时的码率为 At the receiving end the received code packets aliasing, detection is accomplished demultiplexing and decoding coded packets for each user access system based on the decoding method as claimed in claim 1 3.- species; the decoding method is as follows: a receiver receiving coming from the channel, and a steady stream of each user and each added aliasing noise code packet, each user's signal separating and decoding the same time; for user k, k = 1,2, ..., K, its decision decoder and the encoder _k _k using the same random number generator, it is possible to accurately reconstruct the Tanner graph of the code, a demultiplexing and decoding the following steps: (a) receiving a first receiver N = m th code packet aliasing from the channel; (B) a receiver then receives the aliasing ΔΝ code packet, so that N = Ν + ΛΝ, this time code rate
Figure CN101695016BC00031
(C)将接收到的编码包送入解映射及译码软信息估计器_k,采用基于无速率码的多用户随机接入系统的译码软信息估计方法,在当前码率R下进行运算,利用除了判决译码器-k之外其余各用户的判决译码器的输出软信息,初始化时为O,更新估计软信息; (D)将由解映射及译码软信息估计器_k更新得到的估计软信息作为判决译码器_k的输入,在重构的当前码率R下的Tanner图上运行BP译码算法,完成一轮迭代译码运算,并更新判决译码器_k的输出判决结果信息和输出软信息; (E)利用判决译码器_k的输出判决结果信息判断译码结果是否满足Tanner图中校验节点所限制的校验关系,或者迭代次数已经达到所限定的最大次数,如果满足上述两个条件之一,则转入步骤F);否则转入步骤C); (F)利用各个包内的循环冗余校验码判断数据包是否都译码正确,如果都正确,转入步骤G) (C) the received coded packet into soft demapping and decoding information _K estimator, using, for code rate R at the current rate code based on multi-user non-random access method of estimating the soft information decoding system calculating, using the rest of the user information output soft decision decoder in addition to the decision decoder -k, initialization is O, updating estimates soft information; (D) the soft demapping and decoding information by estimator _k update information obtained as a soft decision estimation decoder _k input operation BP decoding algorithm on the Tanner graph in the reconstructed current code rate R, an iterative decoding operation is completed, and update decision decoder _ k output outputs a soft decision result information and the information; (E) using the decision output decoder _k decision result information determines the decoding result meets the limit check the relationship between check nodes in the Tanner graph, the number of iterations has been reached or defined maximum number, if one of the above two conditions satisfied, the process proceeds to step F.); otherwise, go to step C); (F) using a cyclic redundancy check code determines whether data packets are decoded in each packet correct, if correct, go to step G) ;否则转入步骤B); (G)译码结束,接收机发送一个信号告知用户k的发送机停止发送。 ; Otherwise, go to step B); End (G) decoding, the receiver sends a signal to inform the user k transmitter stops transmitting.
4.根据权利要求3所述译码方法,其特征在于,所述步骤(C)中,所述基于无速率码的多用户随机接入系统的译码软信息估计方法具体如下: 设接收机接收到来自信道的,源源不断的,各用户混叠且加上了噪声的编 4. The decoding method according to claim 3, wherein said step (C), a non-rate multi-user-based random access code information estimation method of soft decoding system as follows: Let the receiver receiving incoming from the channel, and a steady stream of each user, and aliasing noise is added compiled
Figure CN101695016BC00032
其中,j为时隙标号,下标I为用户的编号,I = 1,2,...Ka1= Ixi(I), Xi (2),...,Xi(J),...1为第i个用户经信道发送的源源不断的序列,h为信道参数,η= In⑴,n(2),..., n(j),...}为均值为O,方差为σ 2的白高斯噪声序列; 在接收机,根据任一时隙j接收到的编码包包头的用户标示信息,判断出该时隙各用户的信道接入状况:对包头K个比特作硬判决,第k位比特判决结果为I表示第k个用户接入了信道,为O表示第k个用户没有接入信道,k = 1,2,...,K ;然后去掉用户标示信息;用Jk表示用户k的编码包接入时隙的集合,k = 1,2,...,K: Jk = {j xk(j)关O, j = 1,2,...} = {Jk(l), Jk(2) , , Jk(qk),...}; 其中,qk为集合Jk中元素的编号,Qk = 1,2,...;下标k为用户的编号,k = 1,2, ,K;.对于每一个用户,我们要在接收机接收到不同长度的编码包序列I时,即在不同的码率R下,计算其解映射及译码软信息估计器的输 Wherein, j is the reference slot, the subscript I is the number of users, I = 1,2, ... Ka1 = Ixi (I), Xi (2), ..., Xi (J), ... 1 steady stream sequence is transmitted by the i th user channel, h is the channel parameters, η = In⑴, n (2), ..., n (j), ...} is the mean value is O, variance σ 2 white Gaussian noise sequence; receiver according to any one time slot j received encoded packet header user designation information, it is determined that the channel status of each user access to the time slot: to make hard decision header K bits, the k bits for the decision result I represents the k-th user access channel, is O represents the k-th user has no access channels, k = 1,2, ..., K; then remove the user designation information; Jk represented by user code packet access slot set of k, k = 1,2, ..., K: Jk = {j xk (j) off O, j = 1,2, ...} = {Jk (l) , Jk (2),, Jk (qk), ...}; wherein, qk is the number of elements in the set Jk, Qk = 1,2, ...; the subscript k is the number of users, k = 1, when 2,, K ;. for each user, we have to receive different lengths of coding sequence of packets at the receiver I, i.e. at a different code rate R, which calculate the input soft information demapping and decoding estimator 估计软信息,对用户k,设接收机已经接收了N个编码包I = {y (I), y (2),..., y(N)},则当前的码率为R = m/N ; 对于其接入时隙集合Jk中的每一个时隙Jk(qk),其接收到的混叠编码包y (Jk(qk)),可以写作: Estimates soft information, the user k, the receiver has received a set of N code packet I = {y (I), y (2), ..., y (N)}, then the current code rate is R = m / N; Jk for each time slot (QK) which Jk access slot set in which the received code packets aliasing y (Jk (qk)), can be written as:
Figure CN101695016BC00041
其中,^kQk(Qk))为在时隙Jk(qk),非零的其他用户信号和高斯白噪声之和,我们将其称为合并噪声且近似视其为高斯随机变量,均值记为E[ 4k(Jk(qk))],方差记为Var [ ζ k (Jk (qk))],于是可以将接收编码包y (Jk (qk))也视作符合高斯特性:y (Jk (Qk))〜N (jk.Xk (Jk (qk)) +E [ ζ k (Jk (qk))], Var[ ζ k(Jk (qk))]), 其中, Wherein, ^ kQk (Qk)) as slot Jk (qk), other user signals and white Gaussian noise of zero sum, we call them as combined noise and approximately Gaussian random variable with mean referred to as E [4k (Jk (qk))], referred to as the variance Var [ζ k (Jk (qk))], then the packet may be received encoded y (Jk (qk)) is also regarded as a Gaussian characteristic: y (Jk (Qk )) ~N (jk.Xk (Jk (qk)) + E [ζ k (Jk (qk))], Var [ζ k (Jk (qk))]), wherein,
Figure CN101695016BC00042
在解映射及译码软信息估计器_k中,首先按照所选用的映射方式所对应的均值运算规则1^和方差运算规则Γν„,由其余各用户编码包的比特log似然比软信息,算出其余各用户编码包的映射符号的均值和方差;然后按照所选用的映射方式所对应的解映射规则F,由接收到的混叠编码包和已经算出的其余各用户编码包的映射符号的均值和方差,根据接收编码包符合的高斯特性,估计出用户k编码包的比特log似然比软信息; 在第a次迭代时,按照“估计软信息更新表达式” In soft demapping and decoding information estimator _k, first, in accordance with the rules of arithmetic mean of the selected mapping mode corresponding to 1 ^ and variance calculation rules Γν ", the likelihood information of each user log by the remaining bits of code packet softer than calculating the mean and variance of the remaining symbol mapping for each user code packet; then, according to a demapping rule selection of mapping mode corresponding F., mixed by the received stack code packet and have calculated the rest of the user code packet mapping symbols the mean and variance of the received code packets according to a Gaussian characteristic matching the estimated user k the bit log likelihood ratio of the encoded packet soft information; at the a th iteration, according to "soft information estimation updating expression"
Figure CN101695016BC00043
更新估计软信息,式中LL<(V(&))为用户k第a次迭代译码所需的由解映射及译码软信息估计器_k估计出的第qk个编码包的比特log似然比软信息矢量,为用户i第a-1次迭代译码后的第Qi个编码包的比特log似然比软信息矢量;初始化a = I时,Li (= O ; 如果映射方式采用BPSK,将具体的均值运算规则rE,BPSK,方差运算规则rvm,BPSK以及解映射规则Fbpsk代入“估计软信息更新表达式”,可以得到其具体的表达形式: Estimation update log bit soft information, where LL <(V (&)) necessary for decoding iteration of a user k estimated by the demapping and decoding the first soft information estimator _k encoded packet qk soft log likelihood ratio information vector for user i bit log after the a-1 Qi iteration of decoding encoded packets soft log likelihood ratio information vector; initialization a = i, Li (= O; if the mapping scheme employed BPSK, the specific rules of arithmetic mean rE, BPSK, variance calculation rules rvm, BPSK and de-mapping rules Fbpsk substituting "soft information update estimated expression" can get their specific form of expression:
Figure CN101695016BC00051
其中y(Jk(qk)) (c)表示在时隙Jk(qk)接收到的混叠编码包y中的第c个符号,仏)(c))为用户k第a次迭代译码所需的由解映射及译码软信息估计器_k估计出的第qk个编码包的第c个比特的log似然比软信息,^T1 (V(A)w)为用户i第a-Ι次迭代译码后的第Qi个编码包的第c个比特的log似然比软信息; 如果映射方式采用QPSK,则将具体的均值运算规则rE,QPSK,方差运算规则rvm,QPSK以及解映射规则Fqpsk代入“估计软信息更新表达式”,可以得到其具体的表达形式; Wherein y (Jk (qk)) (c) shows the slot Jk (qk) receives the code packet aliasing y in the c-th symbol, Fo) (c)) of a user k is the iteration of the decoding c log of required bits estimated by the demapping and decoding the first soft information estimator _k qk encoded packet soft log likelihood ratio information, ^ T1 (V (a) w) of the user i a- Ι times after the c-th bit Qi iterative decoding of encoded packet soft log likelihood ratio information; if the map mode using QPSK, then calculating the mean specific rules rE, QPSK, variance calculation rules rvm, QPSK and Solutions mapping rules Fqpsk substituting "soft information update estimated expression", you can get the specific form of expression;
Figure CN101695016BC00052
其中,y(Jk(qk))(c)表示在时隙Jk(¾)接收到的混叠编码包y中的第c个符号,LLRak{y(qk\2cA)) , ZZi^(v(&)(2。))为用户k第a次迭代译码所需的由解映射及译码软信息估计器_k估计出的第qk个编码包的奇数位和偶数位比特的log似然比软信息,、OkU)为用户i第a-Ι次迭代译码后的第Qi个编码包的奇数位和偶数位比特的log似然比软信息,Re[.]表示取实部运算,Im[.]表示取虚部运算; 然后将估计软信息矢量作为判决译码器_k的输入软信息矢量,SP令= LLRak(y{qk)),送入判决译码器-k进行第a次的迭代译码;其余各用户也按此同样操作,各用户译码同时进行;完成第a次迭代后,对于用户k,得到其判决译码器-k的输出软信息矢量1^(^),令40(^)) = ^,%4:),其余用户也按此同样操作,接着将相应的值代入“估计软信息更新表达式”,开始新一次的迭代,即第a+Ι次的迭代;以此类推,直至判决 Wherein, y (Jk (qk)) (c) shows the slot Jk (¾) of the received code packet aliasing y in the c-th symbol, LLRak {y (qk \ 2cA)), ZZi ^ (v ( &) (2)) required for the first iteration decoding a user k is estimated by the soft demapping and decoding information estimator _k odd bit qk of the encoded packet and even bit bit log likelihood than the soft information ,, OkU) odd bits and even bits of the log of user i a-Ι iterative decoding of encoded packets Qi likelihood ratio of the soft information, Re [.] represents the calculation taking the real part, [.] Im denotes an imaginary part taking operation; soft information vector and the estimated information vector as input soft decision decoder of _k, SP so = LLRak (y {qk)), fed for the first decision decoder -k a iterative decoding times; Click to the remaining users in the same manner, simultaneously decoding each user; after a completion of the first iteration, for user k, to obtain an output vector which soft decision information decoder -k ^ 1 ( ^), so that 40 (^)) = ^,% 4 :), a user can rest Click the same manner, then appropriate values ​​are substituted into "updated soft information estimation expression" to start a new iteration, ie a + Ι iterations; and so on, until the judgment 译码器-k的译码结果满足Tanner图中校验节点所限制的校验关系或者迭代次数达到所限定的最大次数; 这样可以完成码率R = m/N下的软信息估计,由于编码方式的无速率属性,其编码包序列长度N是不断变化的,我们可以在不同的接收编码包长度下,即各个码率下,运行各自对应的运算,从而完成各个码率下的软信息估计,进而完成信号分离和译码。 -K decoder decoding result meets the maximum number of the Tanner graph the relationship between parity check nodes or the number of iterations reaches the limit defined; this can be done in soft information estimated rate R = m / N, since the encoding no rate attribute mode which encodes the packet sequence length N is constantly changing, we can receive different length code packet, i.e. at each code rate, each corresponding arithmetic operation, thereby completing the soft information at each rate estimate , and then complete the demultiplexing and decoding.
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