Two-channel direct-bit detection receiver for 16-PSK modulated signals

A simple two-channel receiver for 16-PSK modulated signals is proposed and its performance evaluated. Assuming an additive white Gaussian noise interference model, the receiver is shown to be optimum in a minimum bit-error-rate (BER) sense. Using Gray-code mapping and direct detection of individual bits, the overall receiver performance is evaluated as a function of E_b/N₀ and variable phase parameters alpha and beta . These variable phase parameters can be adjusted according to the intended application. A set of values for alpha and beta that is independent of E_b/N₀ exists for the minimisation of the overall BER. However, in applications where individual data streams are interleaved to produce a (higher rate) composite data stream, the value of alpha and beta that is required to equalise the error rates in the delivered individual data streams, is a function of E_b/N₀. Although this represents a slight system disadvantage, it is partly offset by the simplicity with which the receiver is able to deliver deinterleaved data to the intended users.