Simulation of signal-to-interference ratio performance in GSM system employing switched beam smart antenna system

Signal-to-interference ratio (SIR) is a major limitation factor in cellular radio system. Capacity, coverage and quality are general key drivers of deploying any wireless system and they are all a function of SIR. Expanding capacity through conventional methods such as deploying new cell sites or new equipment upgrading is expensive and not always effectives as it will introduce more interference in the current network. With the emerging of smart antenna technology, some performance improvement over conventional cellular system is expected. This paper studies the use of switched beam smart antenna system in mobile communication system for reducing co-channel interference. Simulation has been carried out for GSM cellular system employing various antenna techniques such as omni-directional, directional and switched beam smart antenna. SIR performances are analyzed and results are compared with those obtained when omnidirectional and directional antenna patterns are used in base stations. SIR improvement of at least 6dB throughout the network is achieved when switched beam smart antenna technique is applied in the system.