Comparing the capacities of FH/SSMA and DS/CDMA networks

We present a frequency hopping multiple-access concept suitable for multi-cell network architectures. A set of orthogonal frequency hopping (FH) patterns is assigned to the users in each cell and cells are differentiated by concatenating the user FH pattern with a shuffling sequence of the same hop rate. The use of guard times enables synchronous operation for the range of hopping rates of interest. The capacities of this network for the above FH/SS multiple access scheme with either coherent BPSK modulation or non-coherent BFSK modulation are evaluated for the AWGN channel. The effect of power control errors on the system performance is accounted for in each case. Similar results for asynchronous DS/SS cellular network (reverse link) are also reported for comparison purpose. The comparison is then extended to the Rayleigh fading channel. It is argued that synchronous FH/SSMA is implementable and can provide higher capacity than asynchronous DS/CDMA under certain conditions