Real Co - existence Measurements between UMTS / WCDMA and Ultra Wideband Systems U

This paper presents results from co-existence measurements between multiple ultra wideband (UWB) transmitters and a UMTS mobile phone carried out at the Centre for Wireless Communications (CWC), University of Oulu, Finland. Two environments were explored with the measurements; an anechoic chamber, and inside a shelter (simulating cell boundary conditions). Large numbers of FCC compatible UWB transmitters were used to generate interference in the presence of the active UMTS connection. In the first scenario (anechoic chamber), the voice link was originated between a Universal Mobile Telecommunications Systems (UMTS) radio communication analyser (used as a base station) and a mobile terminal. In the cell edge scenario, measurements were performed using the operating UMTS network. In this case, all UMTS modes (idle, voice and data) were studied. The results clearly show that UMTS and high pulse repetition rate UWB devices can co-exist when a moderate number of simultaneously active UWB devices operate in close proximity of a UMTS terminal. If the number of simultaneously active UWB transmitters close to the UMTS terminal is large, the UMTS connection can be greatly impaired. The results also show that the activity factor of the UWB transmitter disproportionately impacts the effective interference. When using low activity factors, even with high pulse repetition rates and very large numbers of UWB devices, it is difficult to detect UMTS performance degradation. As the activity factors grow beyond 10%, the impact of the UWB interference becomes significant. UWB shows itself to have benign coexistence properties for UMTS when activity factors are low or when the number of active devices is small. Like any technology, a large number of devices leads to significant interference. Index Terms — bit error rate, direct sequence, interference, link quality.