Dynamic Pilot Power Allocation in CDMA Systems

Taking the drawbacks of constant pilot power allocation into account, we introduce an algorithm where the pilot power, especially in a UMTS network, is adapted to the particular downlink cell load condition. By dynamically adjusting the pilot power, interference levels as well as radio emission can be significantly reduced while the network coverage is maintained. The performance of the algorithm is investigated by help of a dynamic system simulator called STEAM (Simulation Tool for the Evaluation of Algorithms in Mobile networks) [1]. For our investigations we consider a rural scenario with 12 sites, 3 sectors each, with a cell radius of 1000 m. The mobiles use a 384 kbps packet data service where data rate adaptation is applied [2]. This packet data control algorithm negotiates the used data rate during call setup depending on the current load situation of the cell. Furthermore, the data rate is adapted to the actual radio conditions and the overload situation. We show that a throughput gain of about 50% can be reached compared to a scenario with constant pilot power of 33 dBm at an overall outage probability of 2% (sum of blocking and dropping).