ADAPTIVE EQUALIZATION FOR COCHANNNEL INTERFERENCE IN A MULTIPATH-FADING ENVIRONMENT

This paper concerns the feasibility and achievable performance of adap tive filtering in an interference-limited multipath fading environment as encountered in indoor wireless communications, In a typical cellul ar radio application, the performance-limiting impairment is interfere nce due to synchronous data streams from other co-channel and adjacent channel users (CCI and ACI). The receiver under consideration employs an adaptive fractionally spaced decision feedback equalizer (DFE) whi ch exploits the correlation of the cyclostationary interference to ach ieve superior performance relative to the worst case when the interfer ence is stationary noise. This paper presents ideal calculations which confirm that significant DFE performance gains are potentially achiev able by explicitly accounting for the cyclostationary CCI. Two adaptiv e DFE strategies are considered. One approach is to adapt the DFE dire ctly using iterative algorithms such as least mean square (LMS) or rec ursive least squares (RLS). Another approach is to compute the MMSE DF E using an RLS CIR estimate End a sample estimate of the CCI autocorre lation obtained from the channel impulse response (CIR) estimation err or during training. The best approach for adaptive equalization, in te rms of adaptation speed and system performance, is to employ an RLS DF E which does not explicitly estimate the CIR or the CCI autocorrelatio n.