适用于M2M通信系统的联合Spinal码传输-随机接入基础理论及优化设计

Considering the characteristics of the M2M communication systems, such as high density of machine type communication (MTC) devices, usually a small amount of data to be transmitted or received, various delay requirements and so on, this project will study on the theory of joint spinal coding and random accessing scheme to decrease the probability of access collision and the access delay, as well as to increase the access throughput and the data transmission efficiency. To achieve this objective, a kind of two-spinal codes, which are obtained by modifying the basic structure of the initial spinal codes, for M2M communication systems will be designed first. The performance of the finite length two-way spinal codes, as well as the asymotic performance, will be analyzed, based on which the optimization of the two-way spinal codes will be discussed. A kind of two-way spinal code with unequal error protection capability will also be designed for some special applications in M2M communication systems. Another theory that needs to be studied is the design of joint physical-layer transmission and random accessing scheme. In this project, we will discuss the design and optimization of a kind of joint two-way spinal coding and random accessing scheme. Specifically, the access throughput of the designed scheme will be discussed first under the assumptation that the codeword length of the error-correcting code employed by MTC device is finite and the maximal number of access users employ the same resource blocks is limited. Then, to maximize the access throughput, the optimization of the access controlling parameters (i.e. access barring), the access resource allocation parameters and the encoding parameters of the two-way spinal codes will be studied. The results of this project will give a systematic theory on the design and optimization of joint physical-layer transmission and random accessing theory.

本项目针对M2M通信系统中MTC设备密度高、短数据包传输、时延需求多样化等特点，在有限长编码约束下，研究适用于M2M通信的联合spinal码传输-随机接入理论，以降低MTC设备的接入碰撞概率和接入时延，提高接入吞吐量和数据传输效率。为此，将首先基于Spinal码的基本原理，设计一类适用于M2M通信系统的双向Spinal编码方案，研究其有限长性能和渐近性能，给出双向Spinal码的优化设计方法，在此基础上设计具有不等错误保护特性的双向Spinal码；然后，研究基于双向Spinal码的联合物理层传输-随机接入(即联合Spinal码传输-随机接入)理论，在有限长编码和限定最大接入用户数的约束下，分析所设计方案的接入吞吐量，并以最大化接入吞吐量为目标，研究接入控制、接入资源分配和双向Spinal码等参数的优化，最终给出适用于M2M通信系统的有限长编码约束下的联合物理层传输-随机接入方案与方法。

针对M2M通信系统中MTC设备密度高、短数据包传输和时延需求多样等特点，本项目研究了适用于M2M通信的联合Spinal码传输-随机接入理论。首先，研究了有限长Spinal码的性能分析及构造方法。在有限长编码约束下，对Spinal码滑窗译码算法的错误概率进行了推导。提出了具有不等错误保护和不等恢复时间性质的无速率Spinal码，并分析了所设计Spinal码的错误概率性能。其次，进行了随机接入方案的设计和参数优化。针对MIMO系统下导频随机接入所面临的导频污染问题，提出一种联合空闲导频接入与最强用户冲突解决(SUCR)的随机接入方案，从而提升导频利用率和用户接入成功概率。为解决拥挤场景下的接入碰撞问题，提出一种联合二分图与SUCR的导频随机接入方案，通过二分图上的干扰消除过程，对碰撞用户进行串行译码，从而提升随机接入吞吐量。针对免授权随机接入方案，提出DNN辅助的随机接入检测算法，通过训练DNN中的权重参数，改善设备活跃性检测和信道估计的准确性。基于非正交随机接入假设，研究了低复杂度的多用户检测算法。针对符号异步上行NOMA系统，设计基于消息传递的异步多用户检测算法，并通过分析证明所提算法的BER性能优于现有算法在同步NOMA系统下的BER性能。针对过载MIMO-NOMA系统，研究了高斯消息传递(GMP)算法的收敛性，提出一种基于扩展和添加操作的GMP(SA-GMP)算法，并证明了在任何过载情况下，所提SA-GMP算法均可实现收敛。对于一般MIMO-NOMA系统，分析检测器与解码器之间的匹配条件，并证明了在任意用户数下，匹配的迭代LMMSE检测器均可实现MIMO-NOMA系统的最佳容量。针对随机接入数据检测中由设备活跃性导致的非线性约束，提出一种基于期望传播的消息传递检测算法。针对M2M通信物理层的多接入信道和突发删除信道，研究了不同的空间耦合码设计方案。通过本项目的研究，降低了MTC设备的接入碰撞概率和接入时延，提高接入吞吐量和数据传输效率。