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In this article we analyze the impact of channel estimation by means of the seconday common pilot channel (S-CPICH) on linear precoding in W-CDMA systems. The pilot sequences on the S-CPICH are transmitted over a fixed grid of beams, causing a systematic channel estimation error at the receiver. Consequently, the adapted rake receiver coefficients will be cormpted due to the use of the S-CPICH, which will lead to an incoherent superposition of the signal components when conventional adaptive space time precoders are employed. Assuming partial channel state information (CSI) at the transmitter we show how the effect of S-CPICH based channel estimation can be reduced or even removed, resulting in an enhanced system performance.

Through the joint optimization of pliysicd (PHY) and media access control (MAC) layer instances, the transmit power, that is necessary to serve given user requirements on throughput and delay, can be minimized. This article shows, how top-down cross-layer oplimization can be extended to scheduled multi-user systems, by formulating analytical expressions for the relevant qualtv of service (QoS) parameters in systems with round robin (RRS), m i m u m tliroughpul (MTS), and propoawnal lair scheduling (PFS). Based on this stochastic description, the power optimal mode oP operation and the minimum transmit powers can be determined providing low complexity means for QoS management, that can be employed to maximize the system capacity.