Path Loss Model and Channel Capacity for UWB–MIMO Channel in Outdoor Environment

A demand for high speed wireless communication system has increased tremendously. Two approaches for fulfilling this demand are to use system with large bandwidth as proposed by ultra-wideband (UWB) systems, or by adopting multiple-input multiple-output (MIMO) antenna systems. This paper presents the path loss model and the capacity of UWB channels in outdoor environment for infostation application. The close in free space and floating intercept path loss models are used to investigate the power decay for the UWB channel. The capacity of the UWB channel is computed based on the measured time-domain data obtained from channel measurement. Comparison between the capacities of UWB single-input single-output (SISO), UWB single-input multiple-output (SIMO), UWB multiple-input single-output (MISO), and UWB–MIMO systems is conducted. The path loss exponent for the MIMO channel is comparable with free space path loss exponent of 2. Result shows an improvement at about 27 bps/Hz in channel capacity for 2 × 2 UWB–MIMO systems when compared to UWB–SISO systems. In addition, we also found that 1 × 2 UWB–SIMO systems achieved higher capacities than 2 × 1 UWB–MISO systems.