Internet无线接入网络中应用智能天线的多址协议及性能分析

该文研究将智能天线应用于Internet无线接入网络的中心接入点(CAP)。提出了基于轮询的自适应波束形成多址接入协议(PB-ABFMA)．该协议中,CAP接收或发送数据分组前,由CAP引导用户节点发送训练序列,CAP的智能天线据此计算出与用户节点对应的权矢量．CAP以轮询及动态TDMA方式为各节点安排发送时隙。采用微时隙为处于空闲状态的节点保持连接以降低时延．设计了一种简单有效的竞争接入算法,保证新用户能快速接入信道．针对Internet中主要的“请求一回应”(request-reply)式业务,分析了协议的信道利用率与平均“请求一回应”时延．结果表明,PB-ABFMA协议能有效支持智能天线应用并具有较高的信道利用率与良好的时延性能。

Multiple Access Protocol for Wireless Internet Access Network with Smart Antennas

Employing smart antennas in the central access point (CAP) of wireless internet access networks is studied, and a polling based adaptive beamforming multiple access protocol (PB ABFMA) is proposed. In PB ABFMA, the CAP stimulates the corresponding mobile terminal (MT) to transmit training sequence just before the data packets transmission, so the temporal reference beamforming (TRB) can be performed by the smart antennas. The CAP schedules packet transmissions based on the polling mechanism, and a mini slot is used to keep connectivity when an MT is idle, thus, the access delay is reduced. A simple and effective collision resolution algorithm is proposed to guarantee rapid access of new arrival MTs to the channel. Based on the "request reply" traffic, the analysis of channel utilization and mean turn around delay is presented. Results show that the proposed protocol effectively supports the application of smart antennas and provide high channel utilization and low turn around delay.