Radio Link Montoring Measurements In Heterogeneous LTE-Advanced System

This paper derives from the cooperation project of Huawei Technologies Co., Ltd and Beijing University of Posts and Telecommunications, "Huawei wireless standard Radio Resource Management R & D projects." Project aims for the fourth generation mobile communication standard 3GPP LTE-A technical standards pre-research which concentrates theoretical study and simulation verification on LTE-A Radio Link Monitoring (RLM), output contributions to 3GPP conference to promote the standards of progress. This thesis focuses on RLM in heterogeneous network.To meet the fourth generation mobile communication system requirements and breakthrough the single-carrier bandwidth limitation (20MHz),3GPP introduces a new technique feature; heterogeneous networks. The introduction of new technology feature to the system has brought great improvement on the performance while also introducing many new challenges to be solved. The user equipments (UE) shall monitor the downlink radio link quality, which depends on physical downlink control channel (PDCCH) block error rate (BLER), and provides feedback to the eNodeB. In heterogeneous networks, since a number of low power nodes are overlaid by a Macro cell and the unbalanced transmitting power are provided between different cell layers, the control channels would suffer more serious interference than in the case of homogeneous networks. Release 8/9 inter-cell interference coordination techniques are not fully effective in mitigating control channel interference, and hence, enhanced interference management is needed. In this paper, RLM performances in heterogeneous LTE-A system are analysed and evaluated based on link level simulation. Further research about enhanced inter-cell interference coordination technology for heterogeneous networks and the related 3GPP proposals are provided through link level simulation platform and the meeting progress, the main contributions are as follows:(1) Constructing the LTE-A RLM baseline link level simulator platform.The simulator is developed according to the RLM simulation parameters provided in 36.133 and the related proposals in 3GPP Working Groups,and consists of several modules,including serving cell signalling, channel modeling, downlink link quality monitoring, PDCCH decoding and etc.(2) Analysis of cell interference variation in heterogeneous scenario, and interference scenarios is determined. Construction of link level simulator with heterogeneous network which is based on LTE-A baseline platform, adding interfering cell signalling and configuration mechanisms for ABS pattern.(3) The RLM performances have been considered in heterogeneous network, and introduced a solution which defines the new RLM measurement requirements. ABS patterns impacts on RLM requirements and side condition of reusing R8/9 RLM measurement requirements are evaluated by link level simulation. Form the simulation results, the impacts of different ABS patterns on RLM performance are very small when the resource-specific scheme is adopted, and ABS position can be flexibly configured. the available generic side condition for interference level can be set as 5dB taking some implementation margin into account.