Research On Radio Resource Scheduling And Interference Management In Broadband Wireless Communication Systems

In the future, broadband mobile communication system will be composed of various wireless access methods, multiple network carrier deployments and hybrid heterogeneous networks to provide users with more convenient services with higher data rates. And it will become a convergence of broadband wireless access and broadband mible communications technologies, as compared with current mobile communication standards. Traditional system design approach and regular wireless system management mechanism may be not appropriate or sufficient for such complicated communication systems and networks. Hence much more efficient radio resource management (RRM) technique is gaining popularity in both academic and industrial respects. The resource allocation in hybrid heterogeneous networks of multiple standards, interference mitigation and interference management for inter-/intra-systems have attracted lots of attention.This thesis concentrates on resource scheduling mechanism and interference management algorithm for RRM. Based on these two aspects, we carry out research on advanced algorithms, theoretical analysis and system level simulation for several access methods, multiple network carrier deployments and hybrid heterogeneous networks. Firstly, intra-cell resource allocation in a single system is studied (research on the scheduling, power control and interference cancellation algorithm in Code Division Multiple Access (CDMA) system); secondly, inter-cell interference management and resource scheduling mechanism are presented (research on the frequency reuse, uplink power control scheme and scheduling design in Orthogonal Frequency Division Multiple Access (OFDMA) system); on the next step, joint scheduling algorithm for multi-carrier aggregation system is addressed; furthermore, interference management in hybrid heterogeneous networks including Macro-cell and Femto-cell are considered (research on the power control, interference coordination and dynamic frequency reuse mechanism. At last, the interference between different coexisting systems is analyzed. The main objective, conclusion and contribution are as follows.(1) Radio resource scheduling mechanism and interference management algorithms are studied and analyzed in CDMA system for cellular networks under wireless communication. A novel scheduling algorithm for delay sensitive service in CDMA forward link is proposed. This algorithm can not only guarantee the frame error rate and delay restriction but also obtain good system throughput and satisfy the fairness criterion. In CDMA reverse link, centralized scheduling and distributed rate control are optimized and discussed. We focus on a distributed rate control algorithm and evaluate its performance in terms of system stability, sector throughput, user fairness and data packet delay. An interference cancellation (IC) system design method is also proposed in CDMA reverse link. System performance is investigated when interference cancellation is adopted based on rise over thermal (RoT) control and Load control respectively. The theoretical capacity for CDMA system is deduced under complete/incomplete interference cancellation technique.(2) The inter-cell interference management mechanism is discussed in OFDMA system network, including downlink frequency reuse technique and uplink power control algorithm. Soft frequency reuse and partial frequency reuse schemes are introduced and analyzed for downlink. The uplink power control algorithm in Long Term Evolution (LTE) system is investigated. Taking a traditional baseline OFDMA system as an example, we study and analyze the basic uplink open loop power control, fractional uplink power control and power control scheme based on path loss difference compensation. And then we discuss the uplink closed loop power control scheme based on interference over thermal (IoT) indicators among cells. System performance of these power control algorithms are evaluated and compared through system level simulation. In addition, theoretical analysis for convergence condition of uplink power control in OFDMA system is carried out. This part also provides deep insight into the problems of how to jointly design the resource scheduling strategy and interference management mechanism. The fast scheduling algorithm and slow uplink power control should be jointly considered in OFDMA system.(3) Two scheduling algorithms for multi-carrier aggregation system are discussed and the performance is analyzed based on dynamic traffic model. The results show that compared with carrier independent scheduling algorithm (CIS), multi-carrier joint scheduling algorithm (MCJS) provides lower queue delay and better user experience when supporting partial load service.(4) The interference management algorithms are investigated for Macro-cell and Femto-cell heterogeneous networks. At first, various interference paths and interference models for different scenarios are introduced, including two typical Femto-cell deployment models:Suburban model and dense urban Dual-stripe model. For these scenarios, we propose three interference management algorithms to achieve different optimization objectives. The first one is a downlink power control algorithm on Femto-cell in Macro-cell and Femto-cell hybrid networks. This scheme decreases the interference from Femto-cell base station to Macro-cell users and improves Macro-cell edge users'experience at the cost of small performance loss of Femto-cell users. The second algorithm is a joint dynamic resource allocation algorithm in hybrid networks. It considers the sum throughput of two-layer networks (Macro-cell network and Femto-cell network) simultaneously through associated dynamic resource allocation mechanism and optimizes the integrated performance of the system. The third scheme is an interference coordination frequency reuse algorithm in dense urban Femto-cell network. This algorithm is based on interference graph theory and divided into two parts:centralized interference coordination and distributed frequency reuse. It can improve both Femto-cell average throughput and cell edge users' experience.(5) Interference analysis and coexistence study between 3G/B3G systems are studied. The assignment of 2.5GHz to 2.69GHz band for expanded 3G band is ongoing in China Communications Standards Association (CCSA) TC5 WG8, so the coexistence study involving three mobile communication systems in the 2.6GHz bands is evaluated. The interference scenarios are for coexistence studies between Worldwide Interoperability for Microwave Access (WiMAX) and Wideband CDMA (WCDMA), between LTE and WCDMA, and coexistence study between two LTE systems. Detailed system level evaluation methodology and system assumptions are presented for these three scenarios. Simulation results under different parameter settings and key technologies are analyzed. At last we give guidelines on radio frequency (RF) parameters for network coexistence and deployment. These results have been accepted by CCSA as an important reference during the assignment of 2.5GHz to 2.69GHz band.