| In wireless digital communications poor data reception has been a long-standing problem, with performance complicated by the effects of interference and fading. In this thesis, the phenomenon of interference has been explored by performance evaluation for single carrier systems. For multicarrier systems, outage probability has been investigated, and a scheme for removal of the interference using receiver signal processing has been studied.; Properties of interference random variables, which commonly occur in digital communications systems, have been studied and techniques for evaluating the expected values of functions of these variables have been presented. These theoretical results are useful in error performance analysis of many types of digital communications systems. The theory has been applied to the computation of error probability in differential detection of GMSK with interference and frequency offsets in Rician fading. The degradation in performance due to the interference is clearly seen in the numerical results.; The outage probability of a signal, when affected by a multicarrier interferer, has been derived for uncorrelated Rayleigh fading, and also for systems with one correlated Rayleigh interferer. Outage probability has been shown to depend on adjacent carrier frequency offsets, time delays relative to the desired signal, and envelope. As envelope correlation between the received desired and interfering subcarriers, increases, outage probability decreases in the low outage probability regions where systems operate typically.; A multicarrier receiver can take active measures to combat interference using a cancellation scheme. Such a scheme has been analyzed, and properties of the cancellation technique have been demonstrated analytically. It has been seen that the larger the interference, the less destructive the effects on signal detection because the present cancellation scheme works better in such circumstances. Performance of the cancellation scheme can be optimized by tuning a single scalar parameter. |
