Optimal allocation of power to AMCS for maximum throughput in WCDMA

In WCDMA systems, the quality of the received signal depends on distance from the desired and interfering sources, path loss and lognormal shadowing. In order to increase the capacity of the system, adaptive modulation and coding (AMCS) is used. With AMCS, we can change the modulation and coding scheme to match the received signal quality. The drawback of using AMCS with the normal power allocation scheme is that in some cases the highest data rate is not obtained. High Speed Downlink Packet Access (HSDPA) is the key part of 3G mobile communications systems. During data transmission in HSDPA, Base stations always transmit at maximum power; several users share fixed number of codes in a frame and AMCS is refreshed on frame by frame-basis. When using AMCS in HSDPA, the object of achieving maximum throughput transforms to find the optimal power allocation method to codes.; In this thesis we explore the effect of power optimization allocation problem to AMCS (or codes) on throughput. With the optimal power allocation scheme, the combination of AMCS is flexible because power is totally assigned to different AMCS. The advantage of using this method is to optimize the throughput so that the highest data rate is achieved for all possible C/I values. As a result of using optimal power allocation, the maximum throughput of multi-codes can be as high as 10.7Mbps. With the estimated error of C/I as 1 dB, the average maximum throughput loss is 10.82%.