| Summary: | 碩士 === 國立臺灣大學 === 電信工程學研究所 === 101 === In recent years, the requirement of cellular network is highly increasing due to fast growing mobile users.However, conventional macro cell with large coverage can not provide advanced channel efficiency because of physical limitation. Thus, heterogeneous networks (HetNets) which increasing density of transmitting node attracts extensive attention. In this thesis, we investigate the problem of coordinated resource allocation for HetNets with low-power RRHs. The scenario we consider is the configuration when RRHs share the same cell ID with the macro BS such that coordinated multi-point (CoMP) operations among transmission points can be performed in a finer granularity without undesirably triggering frequent handover operations. While transmission scheduling in homogeneous networks (HomoNets) has been well developed in the literature, this is not the case for CoMP-enabled HetNets. We first formulate an optimization problem for resource allocation from multiple transmission points to a set of users demanding fair service. Since the problem incurs high complexity, we transform the formulation into an iterative problem for coordinated scheduling under CoMP. To solve the mixed-integer non-linear problem, we propose a two-phase iterative algorithm for sub-channel resource allocation and cross-channel power allocation. Briefly, in the sub-channel sub-problem each sub-channel is handled independently of others for resource allocation while in the cross-channel sub-problem the coupling among sub-channels is considered for proper allocation of the power budget to individual sub-channels. Simulation results show that the proposed algorithm can effectively solve the target problem with noticeable performance gain compared to related approaches. We also observe that conventional strategy of UE selection in HomoNets is not suitable to scheduling in HetNets. CoMP-enabled HetNets have more flexibility in scheduling for improving the cumulative throughput.
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