Improved delay root-Nyquist filters for symbol synchronisation in PCS receivers

With the impending introduction of personal communications systems (PCS) which use hierarchical, multi-rate cellular structures, minimum complexity demodulators will be essential to ensure low-cost mobile terminals. The demodulator complexity may be reduced through the integration of matched filter (MF) and symbol timing recovery (STR) functions. This paper proposes and discusses a number of methods for the design of minimum complexity MFs which incorporate a fractional-sample delay (FSD) for the purpose of symbol timing synchronisation. In particular the down-link (base station to mobile) is considered where near-ideal transmit filters are used and the receive filter's complexity is minimised. The results show that the use of system performance metrics such as ISI and SNR in the filter design procedure can lead to significant performance improvements compared with more traditional methods.