PERFORMANCE EVALUATION OF LINEAR EQUALIZERS IN THE PRESENCE OF ADJACENT CHANNEL INTERFERENCE

An analytical technique is developed to evaluate the error rate and th e minimum mean-square-error (MMSE) performance of linearly equalized M -ary quadrature amplitude modulation and quadrature partial response s ignalling in the presence of adjacent channel interference. Both symbo l- and fractionally-spaced linear equalizers (SSE and FSE) are conside red. The tap gains of these equalizers are evaluated in the MMSE sense . The transfer function and MMSE of the infinite tap SSE are derived i n the presence of interfering channels. The underlying structure of th e infinite-tap SSE is used to develop an infinitely long FSE. Numerica l results indicate that the proposed structure does not yield the same MMSE as obtained by a sufficiently long FSE. A frequency domain analy sis in conjunction with singular value decomposition reveals that the case for the failure of the proposed structure is due to a built-in ra nk reduced property.