ABSTRACT
In recent years, the trend in the spread spectrum communication systems is to use the
combined hybrid techniques. The use of a hybrid systems attempt to capitalize upon the
advantages of a particular method while avoiding the disadvantages. Many different hybrid
combinations are possible; those are: DS/FH hybrid system, DS/time hopping hybrid system,
FH/time hopping hybrid system, and DS/FH/time hopping hybrid system.
In this paper, we will be concern on the DS/FH hybrid system that can combine the
advantages of both DS and FH while avoiding some of their disadvantages. This hybrid
system can combine the anti-multipath effectiveness of DS system with good anti-jamming
and good anti-far problem features of FH systems. Moreover, the hybrid system has shorter
signature sequences and hopping patterns, thus reducing the overall acquisition time. While a
disadvantage of hybrid systems is the increased complexity of their transmitter and receiver.
The paper presents general closed form of the system BER formula which will be derived
assuming non-coherent hybrid DS/SFH-SSMA over AWGN channel and employing MFSK.
Moreover, the analysis is extended to include the derivation of the closed form of BER for
both the pure FH and pure DS SSMA. Then, the hybrid DS/SFH system performance
measures is compared with the performance of both the pure DS-SSMA and the pure FHSSMA
system subjected to the same channel conditions.