面向5G超低延迟和超高可靠性的置换群码与MFSK级联的已编码调制收发信机系统建模

In mission-critical machine-type communication (C-MTC) for typical application areas of 5G, the data transmission between machines puts forward strict requirements of ultra-high reliability and low-latency for radio access, which means that small amounts of data, 10-20 bytes, are communicated with latency as low as 1 ms and reliability of not higher than 10e-9 probability of failed packet delivery within the latency bound. Traditionally, wireless networks, for example, the state-of–the-art LTE network, have not been designed and engineered to achieve such low latency and high reliability simultaneously. For communication for automation of manufacturing cells, this project will investigate a new transceiver architecture which is characteristic with the low data rate, low-latency and ultra-high reliability. Its core technology is to combine the algebraic structural permutation group code (PGC) with multiple-dimension frequency shift keying (MFSK) so as to form a so-called time-frequency shift keying (TFSK) coded modulation system similar to fast frequency hopping (FFH) MFSK system. Its receiver adopts the simple correlation demodulating, the largest envelope detecting and threshold hard decision techniques which can effective decrease the complexity and latency without using pilot frequency, synchronization and channel estimation technique. TFSK system incorporates time diversity and frequency diversity simultaneously and makes full use of the advantage of permutation codes whose error-correcting capability is twice as many as that of the traditional error-correcting codes, so that it can reveal the strong robustness against multipath fading and unintentional multi-tone interferences.

在5G典型应用领域关键业务类型的机器型通信（C-MTC）系统中，机器间的数据传输承受超低延迟和超高可靠性的约束，即传输10-20比特的数据，要求在1毫秒的延迟约束下，误分组率达到10e-9。现有蜂窝移动通信技术及其长期演进计划很难满足这种通信要求。本项目针对工厂自动化的控制信号传输，提出一种低数据率、低延迟和高可靠性的新型收发信机体系结构。其核心技术是将代数结构的置换群码（PGC）与多维频移键控（MFSK）调制技术相结合，形成了类似于快跳频系统的时频移键控（TFSK）已编码调制系统。接收机使用简单的相关型解调、最大包络检测和阈值硬判决技术，不需要使用导频、同步和信道估计技术，有效地降低了收发信机的复杂度和延迟。TFSK系统同时引入了时间分集和频率分集，并有效地利用置换码具有纠错能力高出传统线性分组码一倍的优势，显示出对非蓄意多谐干扰和多径衰落同时存在的无线信道具有较强的健壮性。

本项目以5G的超高可靠低延迟通信URLLC应用为研究背景，试图将定义在正整数域中n个最小正整数集合上的对称群的子群——置换群码这一数学工具，引入到通信领域调制解调技术中，其目的是解决通信系统物理层低延迟通信算法的建模和性能分析等一系列理论和应用问题，涉及编码、调制、解调、检测和解码等算法的结构设计，以及编码调制和检测算法的性能分析，包括信道容量和在AWGN与瑞利衰落信道上的错误概率分析模型的建立。重要结果及其关键数据和科学意义总结如下：1）提出对称群中n！个置换矢量的代数枚举算法，这是抽象代数与计算机科学的有机结合，也是长期困扰数学家的对称群枚举方案的彻底突破，为置换群码的产生方法奠定了理论基础。2）提出当n为任意正整数时，（n, n(n-1), n-1）置换群码的产生方法，并对置换群码的数学结构特征进行了全面分析。3）提出基于置换群码的n维双域调制信号置换阵列星座图PAC框架，建立了PAC框架在AWGN和瑞利衰落信道上的码字错误概率分析模型，这些模型与仿真实验结果十分吻合。采用最大似然算法，PAC调制在AWGN信道上的最好性能优于BPSK调制2dB，在瑞利衰落信道上的最好性能接近AWGN信道的性能。4）提出了PAC框架的陪集编码器，可用移键控技术实现从k位二进制信息序列到n维置换码字的映射，编码器的执行时间为cn个时钟周期（c<n）。使用系统频率为1GHz以上的芯片，意味着系统周期在1纳秒之内。那么PAC编码器的执行时间大约为50~100纳秒。提出PAC解码器，当正确接收n维信号的两个码元时，解码器能够无损解码，恢复发射码字，解码器的执行时间大约在100~200纳秒。编解码器能够满足URLLC应用对低延迟算法的要求。5）首次建立时频分多址（TFDMA）概念，提出TFDMA随机自组网络，其优势是网络的每秒用户接入数达到6528个，可以支持5G的大规模机器型通信（mMTC）应用。