| Recent progress in Internet and mobile communication has attracted much attention. Packet radio network (PRN) can expand Internet service to mobile environment successfully, it also plays an important role in military and commercial communication areas and is interpreted as an integral part of future's personal communication systems.The research work in this dissertation carries a deep study on new techniques of PRN and put emphasis on the multiple access protocol to support the integration of smart antennas with PRN. The major achievements are outlined as follow.Chapter 2 studies the approach to employ smart antennas in mobile ad hoc network (MANET) nodes. The research status of mobile smart antennas (or handheld smart antennas) is reviewed, and the effection of smart antennas on the performance of multiple access protocol is discussed. An adaptive beamforming CSMA/CA (ABF-CSMA/CA) protocol is proposed to support the application of smart antennas and provide higher channel utilization. Theoretical analysis result of channel utilization of ABF-CSMA/CA protocol is presented. Simulation results show that ABF-CSMA/CA protocol can realize space-division-multiple-access (SDMA) and provide very high channel utilization.Chapter 3 considers employing smart antennas in the central access point (CAP) of wireless Internet access networks. A polling-based adaptive beamforming multiple access (PB-ABFMA) protocol is proposed. In PB-ABFMA, the simple and effective mechanism is used to guarantee the smart antennas to adapt the time-varying channel. The CAP schedules packet transmissions based on the polling mechanism and dynamic TDMA. The proposed protocol can be used in synchronous and asynchronous network.Based on the "request-reply" type of traffic in Internet, the theoretical analysis of channel utilization and mean turn-around delay are presented. Analysis and simulation results show that the proposed PB-ABFMA protocols can effectively support the application of smart antennas and provide high channel utilization and low turn-around delay.In chapter 4, we study employing smart antennas in the basestation of packet radio networks. An adaptive slot allocation multiple access (ASAMA) protocol is proposed. Based on the optimal SINR beamforming method, two slot allocation algorithms for ASAMA, called as point-by-point optimizing (PPO) and global optimizing (GO), are presented. On condition that all packets can be received successfully, the basestation dynamically schedules uplink and downlink traffic to achieve efficient SDMA.Approximate analysis of channel utilization is presented. Simulations results under Rayleigh fading channel and ON/OFF traffic model show that ASAMA protocol can effectively support the application of smart antennas and provides high channel utilization and low delay.In chapter 5, we propose a QoS (Quality-of-Service)-supported adaptive slot allocation multiple access (QASAMA) protocol. Similar to ASAMA protocol, QASAMA protocol applies PPO and GO algorithm, but QASAMA protocol also considers the requirements of packet delay, packet drop rate, bit error rate (BER), traffic capacity and channel utilization, and integrates these requirements into the slot allocation procedure. Approximate analysis of channel utilization is presented. Simulation results show that the proposed protocol can support smart antennas effectively and provide high channel utilization and QoS for voice and data traffics.In chapter 6, we proposes a simple adaptive method to estimate the number of nodes who competing channel simultaneously in IEEE 802.11 DCF protocol, so that some parameters of DCF protocol can be adjusted according to the number of competing nodes. Based on the analysis of saturation throughput of DCF protocol, the relationship between the packet collision probability and the number of competing nodes is derived. A packet collision probability based estimation (CPBE) method is proposed, station or AP can estimates the packet collision probability according to several registe...
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