链路服务质量限制下多输入多输出媒体接入控制的建模与分析

摘要

针对SCMA协议没有同时考虑链路服务质量(QoS)和多输入多输出(MIMO)流的信道接入调度策略的不足,提出一种SCMA/QA协议.协议充分考虑了每个链路中不同流的信道状态,建立了一个基于流的信道状态离散马尔可夫链模型,并融合考虑了每条链路的QoS需求,采用修改的RTS/CTS进行链路QoS的信息交换,通过链路QoS权重作为链路选择的主要因素,将MIMO下基于QoS的链路调度问题建模为一个最优化问题,并在卡罗需-库恩-塔克(KKT)条件下得到最优链路以及通信的流数目.最后,以吞吐量为QoS指标进行了数值分析,结果表明在相同网络环境下,SCMA/QA比SCMA和QCSCMA能更好地提高系统的吞吐量.%To solve the insufficiency of Stream Control Multiple Access (SCMA) protocol that it fails to consider both the link Quality of Service {QoS) and the channel access scheduling policy of Multiple Input Multiple Output (MIMO) stream, this paper put forward a SCMA/QA protocol. This protocol fully considered the channel states of different streams in each link and built up a discrete Markov chain model based on channel state of stream. Moreover, it took the request of QoS in each link into consideration and adopted fixed Request to Send/Clear to Send ( RTS/CTS) to exchange the information of link QoS and taking the link QoS weight as a primary case in link decision, made the link scheduling problem based on QoS of MIMO modeled as an optimization problem, which led to the result of optimal link and the number of communication streams under the Karush-Kuhn-Tucker ( KKT) conditions. Finally, according to the numerical analysis which set throughput as the parameter of the QoS, the results show that under the same network environment the SCMA/QA improves the system throughput much better than SCMA and QoS-aware Cooperation SCMA (QCSCMA).