The Effect of a Rapidly Changing Urban Environment on Nomadic WiMAX Performance

This paper presents the results obtained during a three-month trial (February -April 2006) performed by COSMOTE towards the assessment of "fixed WiMAX" technology (IEEE 802.16-2004). The trial was conducted in the three largest cities of Greece, namely, Athens, Thessaloniki and Patra, in parallel, using "fixed WiMAX" equipment offered by three different vendors. The results presented here have been obtained at street-level during stationary measurements performed in the Athens centre, an urban NLOS environment, using a portable WiMAX CPE and a Laptop. The main characteristic of this environment is that it changes very rapidly and quite unpredictably, due to the existence of moving vehicles ranging from motorbikes, to buses and large trucks. These measurements simulate the system performance that an end-user perceives in such an environment, when he/she uses "fixed WiMAX", while enjoying a meal or drink in a restaurant, bar or cafeteria. Preliminary results indicate that in an urban street-level environment, with NLOS channel conditions, large throughput variations are observed, due to the existence of moving vehicles in the radio path. These variations may severely affect the quality of delay-sensitive real-time applications such as, video streaming and video-telephony.