Implementation of opportunistic communication technique using adaptive and Omni-directional antennas in frequency selective fading environment

In this paper basically, two types of antennas like Omni-directional and an adaptive antennas are used at base station using Matlab Rayleigh and Spatial channel models under flat and frequency selective fading environments to analyse the performance of the system in terms of bit error rate using opportunistic communication technique. The spatial channel model used is a geometric model based on stochastic modelling of scatterers and is a more realistic channel model offering three propagation scenarios such as suburban macro-cell, urban macro-cell and urban micro-cell. At the same time an optimal beam-former is also used to isolate the wanted and unwanted user by forming highly directional beam towards the wanted user and a null in the direction of an unwanted user thereby isolating them in space and exploiting the concept of spatial domain by SDMA using an array of 8 antenna elements at base station. For the implementation of different scenarios using both channels it is assumed that the direction of jammer is known in advance. This known direction of the jammer is used to calculate the interference plus noise correlation matrix R_{i + n} so that it can place a null in the direction of jammer.