SINR of antenna array with a large number of interfering users

This paper presents analytical and simulation results on the output SINR of an antenna array for M elements and N interfering users in digital cellular system scenarios. The analytical expressions are given for the following three cases: (i) M=N; (ii) M<N; and (iii) a larger number of weak interfering users are involved. It proves that by lumping the interfering signals into Gaussian noise gives the most pessimistic estimate of SINR (signal to interference plus noise ratio) performance. In the case of (iii), a new approximating approach which results in fairly close performance to the real scenarios in certain cases, is proposed for simplicity of analysis and simulation. The simulation results show that, in practice, the output SINR of the antenna array decreases with an increase in N for fixed M even if N<M. Furthermore it is shown that the SINR is sensitive to the INR (interference to noise ratio)