Channel capacity assessments in uwb communication system over lognormal fading

This paper discusses the assessment of channel capacity for UWB system in the presence of lognormal fading. In frequency-flat channel, we derive the exact expression and the Jensen upper bound of ergodic-mean capacity. Since such an exact channel capacity formula seems to be intractable, we provide its almost closed form, which is manipulated for numerical integration, and then offer some approximate quantities instead. These approximate expressions enable us to investigate the relationships between the channel capacity and SNR. For frequency-selective channel, we elaborate an exact but not closed-form expression of the channel capacity. Numerical expressions are conducted to show the accuracy of several expressions and the channel behaviours. It appears that the channel capacity increases linearly and exponentially with SNR in high and low SNR situation, respectively.