【摘要】 主要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。提出一种简单有效的竞争接入算法 ,保证新用户能够快速接入信道 ,该协议可工作于异步网络中。针对Internet中主要的“请求 -回应”(request reply)式业务 ,推导了信道利用率的计算公式。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更多还原

【Abstract】 The application of smart antennas in the central access point (CAP) of wireless Internet access networks is studied in this paper. 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 packet is transmitted or received by the CAP, so the temporal reference beamforming (TRB) can be performed by the smart antennas. The CAP schedules packet transmission based on the polling mechanism and dynamic TDMA, and a mini-slot is used to keep connectivity when an MT is idle, thus, the access delay is reduced. Meanwhile, a simple and effective algorithm for collision access is proposed to guarantee a quick access of newly arriving MTs to the channel. Based on the "request-reply" traffic, the theoretical analysis of channel utilization ratio is presented. It is shown that the proposed protocol effectively supports the application of smart antennas and provides a high channel utilization ratio and low turnaround delay.更多还原