A Novel Method of Feedback Reducing and Cross-layer Scheduling Based on Traffic Rates for Relay System
A Novel Method of Feedback Reducing and Cross-layer Scheduling Based on Traffic Rates for Relay System
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DOI：
10.1007/s11277-011-0461-x
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发表时间：
2011-11
影响因子：
2.2
通讯作者：
Qianbin Chen;Guang-jian Jiang;Lun Tang;Rong Chai
中科院分区：
文献类型：
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作者：
Qianbin Chen;Guang-jian Jiang;Lun Tang;Rong Chai
本文研究了正交频分多址（OFDMA）多用户下行链路中继系统中的调度方案，其中基站（BS）支持不同用户的不同业务速率。我们将该问题表述为联合反馈减少和 OFDMA 调度的跨层设计，以支持流量速率并最小化丢包率。以往大多数带反馈的调度机制都没有考虑流量到达过程的参数，从而无法保证用户流量的需求。该文提出了一种基于业务速率的动态阈值反馈机制(DTFM)，仅允许信道增益大于动态阈值的用户发送其信道状态信息，从而减少了所需反馈用户的数量以及基站穷举搜索最佳用户的计算负担。在此基础上，提出了一种综合考虑流量公平性、用户队列长度和用户传输速率（与其信道质量有关）的流量和队列比例公平（TQPF）跨层调度算法。最后，提出了一种减少反馈和跨层调度的方法，即基于DTFM的TQPF（TQPF-DTFM）。理论和仿真结果表明，DTFM减少了90%以上的反馈，并且TQPF-DTFM成功地满足了用户流量速率，即高流量速率的用户比低流量速率的用户可以获得更高的传输速率，并且比传统方法使系统丢包率降低近50%。
This paper studies the scheduling schemes in multiuser downlink relay systems with orthogonal frequency division multiple access (OFDMA) where base station (BS) supports different traffic rates for different users. We formulate the problem as a cross-layer design of joint feedback reducing and OFDMA scheduling to support traffic rates and minimize packet loss rate. In most previous scheduling mechanisms with feedback, the parameters of traffic arrival process were not taken into account, consequently, the requirement of user traffic can not be guaranteed. In this paper, a dynamic threshold feedback mechanism (DTFM) based on traffic rates is proposed, of which the user with channel gain being larger than the dynamic threshold is only allowed to send its channel state information, thereby reducing the number of required feedback users and the computational burden of exhaustive search for best users at the BS. A cross-layer scheduling algorithm of traffic and queue proportional fairness (TQPF) taking into consideration the traffic fairness, the user queue length and the user transmission rate (related to its channel quality) is then proposed. Finally, a method of feedback reducing and cross-layer scheduling, i.e., TQPF based on DTFM (TQPF-DTFM), is proposed. Theoretical and simulation results show that DTFM reduces feedback by more than 90%, and TQPF-DTFM successfully meets user traffic rates that is, the user with high traffic rate can obtain more transmission rate than the user with low traffic rate and deceases packet loss rate of the system by almost 50% than the conventional methods.