Propagation measurement based estimation and comparison of DSSS microcellular mobile link performance at 2.25 and 5.8 GHz.

摘要

As a result of increasing demand for greater mobile system capacities, expansion into frequency bands other than the current IMT2000 band near 2 GHz is being considered. Estimation of expected mobile link performance at other frequencies is thus important.; During this thesis project, quasi-simultaneous propagation measurements at 2 and 6 GHz frequencies were conducted in downtown Ottawa. Measurement-based analysis and comparison of time-varying channel characteristics are reported. These show that there is often a larger signal fluctuation after Rake combining at 6 GHz. Results also show that in NLOS conditions, the RMS delay spreads at 2 GHz are slightly greater.; Measurement-based prediction of error performance resulting from the use of Rake receivers on BPSK-DSSS mobile links was conducted. For transmissions with low data rates in IMT2000 bandwidths, self-interference that results from multipath propagation is insignificant, enabling the use of well-known prediction equations. Results show that error performance would be slightly better at 2 GHz. However, channel protection in NLOS conditions would still be required in both frequency bands to achieve BER performance of 10 -3 throughout 2-city block microcells. For the consideration of transmission with high data rates, the effects of self-interference can not be ignored. To accurately account for this, a recently reported semi-analytical BER prediction technique was used. Resulting comparisons of achievable performance in the two bands were similar to those for the low data rate case.