The Distribution of the Bit Error Rate for an M Branch Antenna with N Interferers.

Given an antenna with M branches, the bit error rate (BER) and mean squared error (MSE) for choosing the antenna weights (to approximately cancel M − 1 interferers), are given by where Z is the signal-to-interference plus noise ratio and C, α are some fixed parameters. So, obtaining the distribution of Z allows one to obtain the distribution of the MSE and to approximate that of the BER. Three cases are presented: We assume that Q,..., Q are independent with different distributions. We show that to magnitude 1/ N, the distribution of Z is just that of Q g/ T, where g is a gamma random variable with mean M and T is the average of the total interferer power: We also show how to obtain an expansion in powers of 1/ N for the distribution of $\mathit{TZ}$ about that of Q g. For example, to get the distribution of $\mathit{TZ}$ up to magnitude 1/ N, one requires only the means of Q,..., Q and $Q_1^2,\ldots,Q_N^2$ and the distribution of Q. [ABSTRACT FROM AUTHOR]