The Beamforming Algorithm And Performance Analysis Of Ad Hoc Networks Using Smart Antenna

Ad Hoc networks are decentralized, self-organizing networks capable of forming a communication network without relying on any fixed infrastructure. Ad Hoc networks can be more economical as they eliminate fixed infrastructure costs, and they can be more robust because of their non-center mechanism. However, the capacity of Ad Hoc networks is constrained for its special structure. Recently, many researchers consider smart antenna as an important way to improve the capacity of Ad Hoc networks for it can make full use of electric wave spatial propagation characteristics to enhance system capacity and communication quality. Therefore, this paper analyzes the capacity improvement of Ad Hoc networks benefiting from smart antenna. This paper also gives careful thought to the adaptive beamforming algorithm aim for the enhancement of system capacity and improvement of network performances.First, the characteristics and restrictions analysis of Ad Hoc networks are introduced to demonstrate the significance of using smart antenna in Ad Hoc networks, and the problems that need to be solved are also given. Then, the paper introduces the adaptive beamforming algorithm in detail. Based on the Ad Hoc network structure, we find out the suitable beamforming algorithms LMS and RLS under the criteria of MMSE and we describe the two algothms particularly Secondly, the improvement for the Ad Hoc network hidden terminal with the introduction of smart antenna is discussed, and a new solution to the directional hidden terminal is proposed. We also study the capacity improvement of the network, and analyze the parameters of smart antenna that may impact the capacity of the network. Based on the foundation of basic model, we analyze the capacity improvement of the Ad Hoc network with smart antenna. The simulation result shows that the beam-width and the ratio of side-lobe suppression are the two factors that affect the network capacity.Finally, by comparison of LMS and RLS algorithms, we find that LMS is more suitable for Ad Hoc networks for it has less complexity and lower computable amount and it can also get higher main-lobe gain. According to simulation analysis for different shapes of the antenna array, we can draw the conclution that the linear array is more suitable for Ad Hoc networks. Then research focuses on the bit error ratio performance analysis of the signal with multi-user interferences using LMS algorithm in AWGN channel, rayleigh and rice channel models seperately. Simulation results show that the LMS algorithm can suppress the multi-user interferences effectively in all the three channel models.