Mobile WiMAX is a promising wireless technology approaching market deployment. Much discussion concentrate on whether mobile WiMAX will reach a tipping point and become 4G or not. As a pre-mobile WiMAX system is being delivered, we decided to set up a real life field trial and perform the most important measurements over the system setup. The system was delivered with 4th order diversity. In this paper we analyze physical system performance based on field trial measurements, especially at locations with non line of sight conditions in urban areas. We investigate the gain with 2nd and 4th order base station diversity and derive analytical expressions. The system path loss is plotted and found to approach the Cost-231 Hata model for urban areas. Throughput is also measured and analyzed. Sub-channelization in the uplink points out to be an important feature for enhanced coverage.