Achieving higher HSDPA performance and preserving R99 soft handover control by large scale optimization in CPICH coverage planning

Common pilot channel (CPICH) power is a crucial parameter in coverage planning of today's UMTS networks that implement both HSDPA and R99 services. Adopting a non-uniform allocation of cell CPICH power and minimizing its amount necessary for coverage, the resulting power saving significantly improves HSDPA performance. At the same time, it is vital to have the desired level R99 soft handover, which is heavily influenced by CPICH. In this paper, we demonstrate how large scale optimization can deal with both tasks. Our approach focuses on enhancing cell-edge HSDPA data rate, subject to requirements of CPICH coverage and the level of R99 soft(-er) handover. We present a solution algorithm that optimizes CPICH allocation for HSDPA performance, and, in parallel, offers accurate control of R99 soft handover. Experimental results for large and realistic network planning scenarios demonstrate the benefit of our optimization approach.