Measuring the influence of TX antenna spacing and transmit power on the closed-loop throughput of IEEE 802.16-2004 WiMAX

The impact of transmit-antenna spacing and signal-to-noise-ratio on channel capacity has been measured intensively in a variety of scenarios. When looking at the physical layer throughput of a multi-antenna communication system, the behavior over antenna spacing may look completely different, leading to other conclusions regarding the optimal antenna distance. In this paper, we compare —by testbed measurements— the closed-loop throughput of a standard compliant 2×2 IEEE 802.16-2004 WiMAX radio link with the unconstrained capacity and the mutual information of the channel. Results are presented for base-station antenna spacings of 0 wavelengths (cross polarization) as well as spacings between 0.6 wavelengths and 7.7 wavelengths (equal polarization).