(A) harq scheme with packet error prediction in OFDM based HSDPA systems

Abstract

In the next generation mobile communication systems high throughput and large bandwidth is needed to accommodate the increasing needs of the users, such as Voice Services, Video Conferencing Services, Video on Demand Services, and Multimedia Contents. But to satisfy these demands, the new systems require higher frequency bands. And with the use of high frequency bands the wireless channel effects are increased and the needs of strong equalization techniques are needed. Orthogonal Frequency Division Multiplexing based communication systems can easily overcome wireless propagation effects more than Time Division Multiplexing Access or Code Division Multiplexing Access methods. So OFDM becomes a natural choice for the next generation wireless communication. There will be additional need of using new techniques, such as Turbo Coding, Hybrid ARQ, and Adaptive Modulation and Coding, to guarantee the high throughput requirements. The user equipment or the mobile device only has a limited supply of energy in hand. The used of strong coding schemes such as Turbo Coding increases the power usage per bit in the user equipments. In this thesis, I have proposed a HARQ scheme that predicts packet error using Log-Likelihood Ratio. Using this scheme will allow smaller power consumption in the user equipment due to less use of Turbo Decoding. It will also allow the user equipment to notify the Node-B that the packet received has an error.