| Summary: | 碩士 === 國立交通大學 === 網路工程研究所 === 99 === Long Term Evolution (LTE), one of most promising technology for 4G mobile networks, is the latest standard of 3rd Generation Partnership Project (3GPP). The goal of LTE is to provide high data rate transmission, flexible frequency usage, smaller latency, and supportable transmission in high mobility. To achieve this, LTE employs the modulation technique by OFDMA in downlink and SC-FDMA in uplink, breaking the technical limitations of traditional wireless, and makes itself be the one of members of 4G mobile networks.
To increase the cell throughput and multi-user diversity gain, channel dependent scheduling (CDS) is implemented for the OFDMA-based multi-user scenario to allocate resource blocks (RBs) to users experiencing better channel conditions. Nevertheless, CDS may not perform well in SC-FDMA due to its two inherent constraints－one is contiguous RB assignment and the other is robust modulation and coding mode. In this paper, the formulation of resource allocation for a SC-FDMA system upon considering two inherent constraints is proposed. Since the optimization problem of resource allocation in SC-FDMA is NP-hard, we further propose two heuristic algorithms to find feasible solutions. We evaluate the proposed formulation and heuristic algorithms by conducting simulation. The simulation results show that our methods achieve significant performance improvement in not only system sum throughput, but also transmission delay and outage ratio.
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