中文摘要：

载波侦听阈值的选取对无线多跳网络MAC层的协议性能有着重要影响.已有研究中忽略了确认报文、累积干扰在不同的载波侦听阈值下对系统性能的影响,并在分析中夸大了隐藏节点所导致的信道冲突.针对上述问题,提出了一种结合功率控制的物理载波侦听分析模型.该模型以网络整体性能为优化目标,对全网的累积干扰与空间复用度进行分析,给出节点的平均信道容量.此外,对信道状态建立马尔可夫链模型,提出了4类载波侦听范围内发生的信道冲突以及两类全网累积干扰所引发的信道冲突.分析上述各类冲突对信道利用率的影响,并结合节点的平均信道容量给出优化的载波侦听阈值以及传输功率.与已有研究相比,模型中明确分析确认报文、累积干扰以及隐藏节点对信道冲突的影响.分析结果表明,如果不考虑上诉因素将无法获得最优的载波侦听范围,并且会导致网络性能的下降.

英文摘要：

The choice of physical carrier sensing threshold affects the performance of the MAC （medium access control） layer protocol in multi-hop wireless networks. Previous research ignored the impact of the collisions correlated by ack frame and cumulative interference in determining the optimal carrier sensing range, and the collisions caused by hidden terminal were exaggerated to some extent. This paper presents a new analytical model to get the optimal carrier sensing threshold and transmit power while maximizing the network aggregate throughput. Through analyzing the cumulative interference in the network based on the carrier sensing threshold and transmit power, the channel rate and the number of the concurrent transmissions can be concluded. Additionally, four types of collision happened inside of the carrier sensing range and two types of collision contributed by the accumulative interference are proposed in this paper. Then, the channel activities can be modeled as a Markov chain that reflect the collision referred to above and the channel utilization by this Markov chain model is figured out. This paper investigates the impacts of the carrier sensing threshold and transmit power on the network aggregate throughput that determined by the channel capacity, channel utilization and the concurrent transmissions. Different from previous research, this research identifies the optimal carrier sense range without considering the collision from acknowledgement packet, accumulative interference and hidden terminals. The analysis proves that the aggregate throughput can suffer a loss, if the collision from acknowledgement packet and accumulative interference is not taken into account in determining the optimal carrier sensing range.