|Author:||Chung, Siu-mo Douglas|
|Title:||Performance evaluation of wideband mobile radio system|
|Subject:||Mobile communication systems|
Wireless communication systems
Broadband communication systems
Hong Kong Polytechnic University -- Dissertations
Department of Electronic and Information Engineering
|Pages:||viii, 80,  leaves : ill. ; 30 cm|
|Abstract:||The wideband channel characteristics under urban, suburban and residential area are simulated. Three Power Delay Profile (PDP) models are presumed to represent the above three areas. They are defined as exponential function with different decays according to the propagation behavior of radio waves in the corresponding areas. The path arrival times is assumed to follow Poisson distribution. The time axis is divided into small intervals of 100ns. For each of the intervals, it is to determine whether the path exists or not. The amplitudes of the path follow Rayleigh distribution, which is widely used and adopted to represent the multipath fading. The simulated channel is then characterized by the Average Power Delay Profile (APDP), Average Excess Delay (D) and RMS Delay Spread (τrms). The distribution of D and τrms are also presented and compared with field experiment results. Moreover, τrms is found to be larger in urban area than the other two. Normalized RMS Delay Spread, which is the product of data rate and τrms, is commonly used to describe the performance of a wideband mobile radio system. However, the simulation results show that it is not sufficient to just describe the performance by using the normalized RMS Delay Spread only. The simulated channel is then used to evaluate the system performance. The system performance is referred to the Bit Error Rate (BER) of the system. The BER is found to be very high in urban area due to significant multipath effects. The system can be improved by using spread spectrum technique with rake receiver. Rake receiver makes use of the multipath nature to increase the Signal-to-Interference ratio, hence reduce the BER. There are quite significant improvement on the system performance. Some Power Delay Profiles (PDPs) obtained from field experiments around the Hong Kong Polytechnic University Staff Apartment at Tsim Sha Tsui are used to evaluate the performance. Some profiles are found to have small τrms and some have large τrms. The results are then compared with the simulated one.|
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