超蜂窝架构下基于跳码的SCMA控制信道接入设计  被引量:2

An SCMA control channel accessing scheme based on codebook-hopping under hyper-cellular network architecture

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作  者:廉晋[1,2] 周世东[1,2] 张秀军[1,2] 王玉锋[1,2] 

机构地区:[1]清华大学电子工程系,北京100084 [2]清华信息科学与技术国家实验室(筹),北京100084

出  处:《中国科学:信息科学》2017年第6期789-799,共11页Scientia Sinica(Informationis)

基  金:国家重点基础研究发展计划(973)(批准号:2012CB316002);国家高技术研究发展计划(863)(批准号:2015AA01A701);国家自然科学基金(批准号:61201192;61631013);国家科技重大专项课题(批准号:2016ZX03001009);清华大学自主科研项目(批准号:2015Z02-3)资助项目

摘  要:为了实现高能效绿色通信同时满足高速增长的业务量需求,未来网络将引入超蜂窝架构,通过控制与业务覆盖分离的方式实现柔性覆盖.在超蜂窝架构里,当用户有业务需求时,将免授权地随机接入控制信道发送请求信令.作为目前较为理想的随机接入方案,稀疏码多址接入(sparse code multiple access,SCMA),通过为用户分配不同码本实现非正交多址接入,从而在资源数一定的情况下提升系统的容量,允许大量用户同时接入,进而可以作为控制信道中的随机接入方式.然而,在随机接入的过程中,可能会出现采用相同码本的用户同时接入的情况,称之为码本碰撞,这会导致接收性能的恶化,并且解码算法的运算量随着码本碰撞的用户数成指数增长,严重增加了最坏情况延时.为此,本文提出一个基于时变码本的跳码方案.仿真结果表明这一新方案提升了解码准确性,进一步通过在发生严重码本碰撞时有选择地抛弃SCMA子块,可以在较低的误码率代价下大大降低整体的解码延时,从而满足控制信令高可靠、低延时的传输需求.To satisfy the growing demand on data traffic in hyper-cellular networks while at the same time ensuring high-energy efficiency, soft coverage can be effectively utilized in networks, by separating the control and data channels. In this view, with no data to be transmitted the system is in the sleep mode, and with a certain demand on data transmission the system will wake up and will send control signals in a grant-free manner. As one of the most promising random access schemes, Sparse Code Multiple Access (SCMA) allows users to adopt dedicated codebooks to send their data, with superposed code words. However, owing to the lack of scheduling in random access, different users may accidentally use the same codebook, which is called codebook collision and would result in performance degradation. To alleviate this degradation, we propose a codebook-hopping scheme by adopting time-variant codebooks with different patterns for different users. Simulation results show that the proposed scheme improves the performance in terms of the block error rate. In addition, with selective elimination of SCMA sub-blocks in the case of severe codebook collision, the complexity and latency of decoding can be significantly reduced. By doing so, the system can achieve high reliability and low latency for controlling signals in hyoer-cellular networks.

关 键 词:绿色通信 超蜂窝 控制信道 免授权接入 SCMA 

分 类 号:TN929.5[电子电信—通信与信息系统]

 

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