Channel Capacity in a Dynamic Random Waypoint Mobility Model

Abstract

In this paper the channel capacity for a dynamic random waypoint (RWP) mobility model of a Rayleigh fading channel is derived. A maximum ratio combining (MRC) diversity receiver and the effect of the number of branches, N, on the channel capacity is determined. As expected, by increasing the number of diversity branches, the resulting channel capacity is increased until the capacity is saturated. For example, the channel capacity for N = 3 is increased by 38.3% compared to no diversity ( N = 1 ) for the same value of the average received signal-to-noise ratio $\left( {\overline {{\text{SNR}}} } \right)$ but increasing N beyond 12 provides minimal gain. The channel capacity is compared with the classic Shannon capacity of the AWGN channel and with the well-known static model Rayleigh fading channel capacity. The channel capacity of the RWP Rayleigh channel is reduced by 10% compared to the AWGN Shannon capacity for a $\overline {{\text{SNR}}} $ of 20 dB. As expected, the AWGN channel capacity has a larger channel capacity as it is not affected as severely by fading as in the RWP mobility model. By contrast, the RWP model shows a slight improvement in channel capacity in comparison with the static model Rayleigh fading channel, since it will not be affected by severe fading for as long a time period as the static Rayleigh model. For example, the proposed model channel capacity increases to 6.11 bps/Hz whereas it is 5.87 bps/Hz for the static model Rayleigh fading channel capacity at the same $\overline {{\text{SNR}}} = 20{\text{dB}}$ with increasing of 4%.