Optimal Cognitive Access and Packet Selection Under a Primary ARQ Process via Chain Decoding
Optimal Cognitive Access and Packet Selection Under a Primary ARQ Process via Chain Decoding
复制标题
通过链式解码实现主 ARQ 过程下的最佳认知访问和数据包选择
DOI：
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发表时间：
2016
影响因子：
2.5
通讯作者：
M. Zorzi
中科院分区：
文献类型：
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作者：
Nicolò Michelusi;P. Popovski;M. Zorzi
本文介绍了一种新的技术，使认知次用户（SU）的现任主用户（PU），采用类型I混合自动重传请求（ARQ）占用的频谱接入。该技术允许SU对先前传输失败的SU数据分组执行选择性重传。由PU ARQ协议和由SU的选择性重传过程引入的时间冗余可以由SU接收器利用以在多个传输时隙上执行干扰消除（IC），从而创建用于对并发SU或PU分组进行解码的“干净”信道。链解码（CD）技术由SU或PU分组的成功解码操作发起，并且随着先前缓冲的分组变得可解码并且它们的干扰可以被去除而通过IC的迭代应用而继续，从而使得可以恢复并发数据分组等等，直到没有更多的分组可解码。在此基础上，设计了一个最优策略，在平均长期PU性能的约束下，最大化SU吞吐量。证明了CD协议的最优性，它决定了SU在任何给定时间应该发送哪个数据包，基于四个基本规则。此外，一个解耦原则的证明，建立了最优的解耦二级访问策略的CD协议。具体而言，首先，通过动态规划优化的SU访问策略基于协议的紧凑状态表示来指定SU应该访问信道还是保持空闲，其次，CD协议嵌入了用于选择SU发送的分组的四个基本规则。数值结果表明，CD优于高达35%的其他计划在文献中考虑，不采用重传在SU对，从而不利用IC的全部潜力。
This paper introduces a novel technique that enables access by a cognitive secondary user (SU) to a spectrum occupied by an incumbent primary user (PU) that employs Type-I hybrid automatic retransmission request (ARQ). The technique allows the SU to perform selective retransmissions of SU data packets, whose transmission previously failed. The temporal redundancy introduced by the PU ARQ protocol and by the selective retransmission process of the SU can be exploited by the SU receiver to perform interference cancellation (IC) over multiple transmission slots, thus creating a “clean” channel for the decoding of the concurrent SU or PU packets. The chain decoding (CD) technique is initiated by a successful decoding operation of an SU or a PU packet and proceeds by an iterative application of IC as previously buffered packets become decodable and their interference can be removed, thus making it possible to recover the concurrent data packets, and so on, until no more packets are decodable. Based on this scheme, an optimal policy is designed that maximizes the SU throughput under a constraint on the average long-term PU performance. The optimality of the CD protocol is proved, which determines which packet the SU should send at any given time, based on four basic rules. Moreover, a decoupling principle is proved, which establishes the optimality of decoupling the secondary access strategy from the CD protocol. Specifically, first, the SU access policy, optimized via dynamic programming, specifies whether the SU should access the channel or remain idle, based on a compact state representation of the protocol, and second, the CD protocol embeds four basic rules that are used to select the packet transmitted by the SU. It is shown numerically that CD outperforms by up to 35% other schemes considered in the literature, which do not employ retransmissions at the SU pair and thus do not exploit the full potentiality of IC.