A Load-Based Offloading Scheme for Mitigating Ping-Pong Effect in Heterogeneous Cellular Networks

  • 葛 庭瑞

Student thesis: Master's Thesis


The development of small cells which shifts the traditional macro-based homogeneous network to the heterogeneous networks (HetNets) is regarded as one of the major breakthroughs to improve the network capacity With the traditional Max-SINR association scheme a user will choose the base station (BS) which offers the strongest received signal strength as its serving BS Consequently severe congestions may happen at the high-power macro base stations (MBSs) because most users tend to associate with the more powerful MBS rather than the low-power pico base stations (PBSs) To release the congestion problem users can be shifted from the overloaded BSs to other BSs known as user offloading However without taking the BS load into consideration users may be offloaded to a neighboring BS that is overloaded leading to failure cell association that is undesirable from both users' and operators' perspectives In this work we propose a load-based offloading scheme to address the aforementioned issue We first formulate the optimal load-based offloading problem and shows that it is NP-hard To facilitate practical implementation a heuristic algorithm is proposed that is featured by the use of an offset parameter to mitigate offloading users to over-loaded BSs From simulation results the proposed heuristic algorithm is shown to increase the association rate and the average user rate as compared to the traditional offloading scheme without considering the BS load
Date of Award2015 Jul 8
Original languageEnglish
SupervisorKuang-Hao Liu (Supervisor)

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