Propagation characteristics of a frequency hopped channel

Frequency hopping (FH) CDMA has received relatively scant attention, although recently there have been some encouraging publications which claim that FH can achieve a similar performance advantage to that claimed by proponents of direct sequence (DS) CDMA. In order to allow a more detailed investigation of a feasible rival FH architecture, and select the modulation format and coding scheme to optimise its performance, essential data about the characteristics of a frequency hopped channel is required. The paper describes measurements undertaken in the City of Bristol to investigate the FH environment. The results show that although the long term statistics, such as the cumulative distribution, exhibit negligible differences between hopped and fixed frequency operation, the instantaneous effects differ considerably. These include the level crossing rate and mean fade duration, and could significantly influence the requirements for FH system design