Coding and modulation tradeoffs for limiter-discriminator based CPM transceivers are examined in Rayleigh, fast fading environments. Comparisons are made on the basis of a fixed bandwidth to information rate ratio, so coded schemes and uncoded schemes can be compared fairly. It is shown that using the proper balance of modulation and coding is important to achieve good performance. It is found that combining bandwidth efficient modulation with convolutional coding achieves better performance than trellis coded modulation (TCM). The increase in performance as the code complexity is increased is also found to be larger for convolutional coding than for TCM.

In our previous research, to achieve unequal error protection (UEP), we proposed a scheme which encodes the data by randomly switching between several codes which use different signal constellations and showed the effectiveness in AWGN channels. In this letter, we propose our UEP system using MMSE-FDE for fast and selective fading by using the fact that importance levels are changed every few symbols, i.e., every block, in the proposed system. We confirmed the improvement in BER performance and the effectiveness of adaptive equalization for the proposed system in fading channels. Moreover, in fading channels we confirmed the validity of the theoretical tradeoff shown in static conditions.