Multiuser detection for MFSK frequency-hopped multiple access system

Abstract

The capacity of a multilevel FSh' (MFSK), frequency-hopped multiple access (FHMA) system is dictated b y two major design concerns: the hopping pattern and the receiver structure. This paper studies the i:mpacts of both factors. W e present a maximum likelihood (ML) diversity combiner for asynchronous FHMA systems in Rayleigh fading and compare systems using random hopping patterns and those that use a set of optimal hopping patterns. On the other hand, a multiuser detector for an FHMA/MFSK system usually consists of two stages. The first stage makes an initial decision while the second stage tries to resolve the ambiguity and reduce the cochannel interference (CCI) left b y the first stage detector. After analyze the performance of the first stage detector thlat uses appropriate diversity combining, we then examine the effectiveness of a second stage detector which is a modification of an earlier structure developed b y Timor. This receiver is of modest complexity and is capable of removing most of the CCI. Moreover, we also find that it is insensitive t o power variations of the system users.

Frequency-hop multiple-access systems with limited per-hop multi-user detection

“…The set of frequency slots can be used by the receiver to identify the user, and the transmitted signal conveys the data. An other general approach is discussed in [7] for fast-frequency hopped multiple-frequency shift key (FFHlMFSK). Because each symbol is transmitted on multiple hops, a two-stage receiver attempts to use knowledge of the hopping patterns to cancel known interference.…”

Non-coherent multi-user detection of DPSK signals after differential demodulation

“…Several MUD approaches have been considered for FH systems (e.g., [4], [5], [6], [7]). Limited per-hop MUD for FH [8] is of particular interest here.…”