Load Balancing in Heterogeneous LTE-A Networks

University essay from Linköpings universitet/Linköpings universitet/Kommunikations- och transportsystemTekniska högskolan; Linköpings universitet/Linköpings universitet/Kommunikations- och transportsystemTekniska högskolan

Author: Kennedy Ronoh; Awoke Mengistie; [2012]

Keywords: ;

Abstract:

LTE-A is the latest cellular network technology. One feature of LTE-A is the use ofheterogeneous networks (HetNets) which consist of macro-cells and low power nodes(LPNs). One of the objectives of heterogeneous networks is to increase capacity especially inhotspot areas where there is high density of users. Due to their low transmit power, very fewusers associate with LPNs and this will result in load imbalance between LPNs and macrocells.Load balancing is therefore key issue in HetNets so as to maximize cell splitting gainsand ensure even user experiences. Cell range extension (CRE) is a technique that can be usedto achieve load balancing in HetNets. Under CRE, an offset is added to LPNs during cellselection so as to expand the range of LPNs and offload more users from macro-cells toLPNs. CRE usually involves the use of uniform offsets. The use of uniform offsets results insome degree of load balancing in a HetNet which is not optimal. This arises because differentLPNs require different offsets due to varying conditions such as user distribution andpropagation environment in different hotspots. The use of cell-specific offsets is necessary forimproving the level of load balancing in HetNets. In this thesis a heuristic load balancingalgorithm that is used to assign cell-specific offsets to LPNs is designed. The algorithm makesuse of a range optimization framework which applies the concept of cell load coupling. Ourresults show that the use of the cell-specific offsets results in not only a high degree of loadbalancing as measured by Jain’s fairness index but also more even user experiences in termsof throughput.

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