Efficient Transmission over Unknown Channels

University essay from Lunds universitet/Institutionen för elektro- och informationsteknik

Abstract: In recent years, digital transmission techniques have been continuously evolving by employing increasingly more advanced Modulation and Coding Scheme (MCS). However, when the wireless channel is varying rapidly, it is hard or even impossible for the transmitter to select the proper MCS. In this thesis work, a high MCS is employed at the transmitter, irrespective of channel conditions, in order to exploit the channel in an opportunistic way. A detailed description of Multi-Layer Transmission (MLT) using high MCS in combination with the Hybrid Automatic Repeat reQuest (HARQ) scheme is presented, and its performance is compared with the traditional transmission technique with the aid of Matlab simulations. The thesis illustrates the gain in the performance of mixing layers in MLT and also outlines the idea of employing successive demodulation at the receiver side. Furthermore, the performance of MLT with the basic ARQ scheme is also investigated in this thesis work.

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