This paper exploits the concept of diversity using adaptive antenna at BS, where different users are communicating with BS from different locations but at same frequency in flat fading and frequency selective environments. In this paper in the simulations it is assumed that there is one jammer whose direction is known in advance. Therefore it uses the known direction of the jammer to calculate the interference plus noise correlation matrix Ri???n so that it can place a null in the direction of jammer. When user-1 is communicating with the BS a composite signal is received using the optimal beamformer that forms main beam towards user-1, while placing a null towards user-2 considering it as a jammer. The interference plus noise correlation matrix Ri???n is used to find the weight of an optimal beamformer. The opportunistic communication method has been implemented using Matlab Rayleigh and Spatial channel model (SCM) developed by 3rd generation partnership project (3GPP). The main focus is on comparison of results using SCM and Matlab Rayleigh channel and is shown with the help of simulations that SCM provides an improvement in terms of bit error rate (BER) as compared to Matlab Rayleigh Channel. The BER performance of SCM systems is much better thereby showing an improvement of about 5dB in flat fading environment which is achieved because of exploitation of spatial diversity offered by SCM. In case of frequency selective fading environment there is an improvement of 2-3 dB for two users while using SCM as compared to Matlab Rayleigh channel by exploitation of diversity in both spatial and time domains.
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