Performance of FH/MFSK systems with readable erasures

We propose a readable-erasure channel for frequency-hopping spread-spectrum multiple access systems with MFSK modulation scheme (FH/MFSK). In contrast to the conventional erasure-only channel having M + 1 output symbols, the proposed readable-erasure channel has 2M output symbols. Half of the symbols are related to hit-free transmissions, and the rest of the symbols, referred to as weak symbols, are related to transmissions that were hit. The essence of the readable erasure is in the information hidden inside it. One may explore such information by using channel coding. Our analysis shows that in conjunction with channel coding, the readable-erasure channel may enjoy performance advantage over the erasure-only channel. By taking the spectrum efficiency into consideration, we point out that using RS codes over large channel alphabet size in FH/MFSK systems is inefficient. Thus, for FH/MFSK systems, we suggest BCH codes over GF(4) for use with the readable-erasure channel.