Smart Antenna Technologies In Ad Hoc Network Terminals

As the main personal communication tool in the future, the mobile wireless technology has received enormous interest according to the rapid growth of the global communication services. This growth has triggered a confliction between the needed capacity and the limited radio spectrum resources. Several new technologies have been explored and deployed in this regard to make effective usage of the limited resources. Space Division Multiple Access (SDMA) has emerged as a key technology and holds a lot of promises for the future mobile communication. Smart antenna technology has received enormous interest world-wide since 1990s.Multi-antenna technology can decrease the signal interfering in the third generation mobile communication system while the space division processing could increase CDMA capacity. The excellent increase in spectrum utilization made smart antenna technology play a significant role in the forth generation communication system. Generally speaking, smart Antenna technology can be used in base stations and mobile terminals. The later one is especially valuable in the military communication and the emergency communication systems. The antenna size and algorithm complication limit the development of the technology usage in mobile terminals. A wireless ad hoc network is comprised of nodes communicating with each other without infrastructure support. Recently, some scholars proposed to use smart antennas instead of omni-directional antennas in the Ad Hoc network terminal, which means huge increase in capacity, decrease in signal interfering and finally great increase in communication quality.The dissertation focus on the beamforming algorithm used in the Ad Hoc network terminal, the DOA estimation algorithm used in the Ad Hoc network terminal, the Ad Hoc Network mobility model and the DOA tracking/prediction in the Ad Hoc network terminal.Based on Butler matrix, a novel simple structured hybrid smart antenna system applicable in Ad hoc network terminals is designed. A super resolution beamforming algorithm—BSRBA is also presented by combining with the direction of arrival (DOA) estimation algorithm of digital signal processing (DSP) .By this algorithm , it is deduced the shift value formula of the variable phase shifter when the antenna array switches to the direction of the desired signal. Simulation results show that the system facilitates the implementation by use of the simple system structure and easy beamforming feature. And it can drive the antenna to follow the input signal, which can greatly improve the signal quality and suppress the electromagnetic interference.A novel pilot-assistant DOA estimation algorithm is presented based on the Butler matrix. The orthogonal channel code is used to avoid the correlation between the desired signal and the interference. The algorithm is combined of a rough estimation stage and an accurate estimation stage which are mostly fulfilled by hardware. It approaches the DOA of the desired signal iteratively through the variable phase shifter. And the accuracy of the algorithm can be decided by users. The merits of its low-complexity and quick convergence make it suitable to be used in Ad-Hoc network terminals.A Direction of Arrival (DOA) estimation algorithm is presented based on the eight unit circulararray which can cover 360°plane excellently. The algorithm is simulated in 2K mode of DVB-T system.Two Ad Hoc mobility models are presented in the dissertation: SMART for the entity mobility model and GSMART for the group mobility model. The models comprehend various situations of Ad Hoc mobile terminals and are more practically comparing with the linear mobility model .They have the merits of large usage range, variable parameters. The acceleration speeds can also be extended or reduced according the real application.A novel Sequential Monte Carlo algorithm is provided for the multiple maneuvering Ad-hoc network terminals Direction of Arrival (DOA) tracking and prediction. We establish a nonlinear mobility and observation model which can describe the motion features of the Ad-hoc network terminal more practically. The algorithm does not need any additional measurement equipments. Simulation result shows its significant tracking accuracy...