有效支持智能天线在MANET中应用的多址接入协议

Multiple Access Protocol in Mobile Ad Hoc Networks with Smart Antennas

在充分考虑智能天线与MANET特点的基础上提出了自适应定向CSMA/CA(AD-CSMA/CA)协议,该协议利用RTS/CTS短分组对话实现信道预约;在RTS与CTS分组中设置了训练序列,收发节点的智能天线基于训练序列进行自适应波束形成并传输数据分组与ACK;使用改进的“虚拟载波监测”机制进行冲突避免(CA)与分组发送过程的合理安排,用仿真方法对该协议的性能进行了评估,讨论了节点传输距离,数据与控制分组长度以及天线模式切换时间对网络性能的影响,仿真结果表明,AD-CSMA/CA协议与智能天线的结合能够有效实现信道的空分复用(SDMA)从而显著提高整个网络的信道利用率。

Smart antennas technology is now regarded as one of the hot-point research areas in mobile communications. However, its application to the mobile or portable nodes receives little attention. The approach to employ smart antennas in mobile Ad Hoc network nodes is presented. The emphasis of smart antennas on the performance of the multiple access protocol is discussed. An adaptive directional CSMA/CA (AD-CS-MA/CA) protocol for medium access control (MAC) layer is proposed. In Ad-CSMA/ CA, RTS/CTS dialogue and virtual carrier sense are combined with the use of smart antennas. Simulations show that the proposed AD-CSMA/CA protocol together with smart antennas provide higher channel utilization.