Simple expression for interchannel and intersymbol interference degradation in MSK systems with application to systems with Gaussian filters

In this paper, a simple expression is derived for the degradation in signal-to-noise ratio caused by intersymbol and adjacent channel interference in MSK systems for which the total response is nonnegative and the response is such that only two intersymbol and one adjacent channel terms are dominant. An MSK system with Gaussian filters in transmitter and receiver satisfy this condition. The resulting expression is simple because the signal value from the main channel (by selecting the sampling time) and the degradation caused by the signals in the interfering channels are maximized simultaneously. For such systems, the relation between the optimal filter bandwidth and channel frequency separation is derived. Numerical results are presented for the case of Gaussian filters in both transmitter and receiver or receiver only and either one or two adjacent interfering channels.