| With development of diverse radio access technologies, the heterogeneity has been one of the most prominent characteristics for wireless communication networks. Meanwhile, with increasing services demands from subscribers, any single radio access network (RAN) can not provide all services for users, which motivates the future wireless communication system to move towards the trend of cooperation and convergence. Therefore, two prominent characteristics are emerged as the most promising trends of the future advanced wireless communication system:one is network heterogeneity; another one is cooperation and convergence of heterogeneous networks. However, differences of system architecture, resource pattern and management mechanisms across diverse RANs lead to following revolution roadmap of heterogeneous networks:from isolation to interworking, from interworking to cooperation, from cooperation to convergence. In this roadmap, common radio resource management is the key mechanism to fulfill the orderly and efficient cooperation across heterogeneous radio networks.According to the trends of future advanced wireless communication systems, this dissertation investigates on common radio resource management mechanism and proposes several algorithms including joint session admission control, mobility management, traffic allocation and joint resource scheduling from the perspective of system level, traffic stream level and data packet level respectively. The main contents and contributions of this dissertation are presented as follows:A prototype framework of the joint management and control is proposed to support cooperation across multiple RANs and multiple terminals. The proposed framework and function models are overlaid upon the architecture of existing networks. With this method, it not only can support interworking across heterogeneous networks, but also can support cooperation transmission across multiple terminals. Furthermore, the proposed function models could take control of traffic flows from the application layer and transport layer, it also could carry out coordination of traffic transmission and resource allocation among different RANs through the governing of RRM models in existing networks; at the same time, with assistance of context-aware server, the proposed framework could deal with the diverse information from network environment, radio link environment and subscriber environment to support decision-making for joint management & control in different layer. The proposed prototype framework and function models have been implemented in the test bed of convergence across wireless personal area networks (WPANs) and wireless wide area networks (WWANs) under the support of Chinese High-Tech R&D program (863 program).Joint admission control is the first step of the user communication to radio network, and it is also the basic strategy to carry out other common radio resource management schemes including mobility control, traffic allocation and resource scheduling in heterogeneous radio environments. As to the diversity and multi-dimensional characteristics for the criterions impacting on decision-making of access control, a joint admission control mechanism based on multi-dimensional vector space model is proposed and analyzed. The proposed mechanism includes network selection, access probability management and access control. In network selection and access control schemes, each criterion impacting on algorithm decision-making is regarded as one dimension in vector space; as a result, the multiple dimensional vector space considering admission control attributes is constructed to analyze the relationship between user target vector and network ability vectors. With analysis of distance and decomposition characteristics among vectors, it could solve both problems of "how to select the most appropriate network for users" and "how to coordinate heterogeneous resources to admit users" Furthermore, the proposed access probability management sets different access priorities for various services, which not only could guarantee QoS for high priority service, but also could prevent repeat transmission of access requirements from low priority services to avoid system performance deterioration. And the proposed access probability management is the precaution strategy for access control in the situation of multiple users.Mobility management is the key mechanism to guarantee seamless handover across multiple radio networks for users. However, in heterogeneous radio environments, lots of multi-mod terminals will send handover requests at the same time or nearly simultaneously due to group mobility, which is defined as group vertical handover (VHO) scenario. In order to solve the decision-making problem under uncertain and imprecision information in the proposed group vertical handover scenario, three decision-making models are presented from the perspective of terminal controlled and network controlled methodology. The first and the second model belong to distributed decision-making based on terminal controlled methodology. The first model introduces time window to separate simultaneous arriving VHO requests in time sequence. Based on the concept of risk aversion in microeconomics, the second model set different types of probability distribution according to network abilities, and makes use of these probabilities to distribute numerous simultaneous arriving VHO requests to different networks to avoid network congestion. The third model adopts centralized decision-making based on network controlled methodology, and the proposed model can collect information from both user and network sides to make global optimized decision. The simulation results indicate that the three proposed models can effectively make vertical handover decisions under the conditions of uncertain and imprecision information.The goal of network cooperation and convergence is to provide more reliable traffic transmission quality and better service experience to subscribers, at the same time, the cooperation across multiple RANs and terminals would influent on traffic transmission model. Therefore, a traffic allocation scheme with cooperation of WPAN and WWANs is proposed to analyze how to distribute traffic flow to different networks, which aims to optimize overall system performance according traffic allocation schem. The single-mode terminals could be connected by WPAN techniques as terminal subsystem to extend their limited receiving ability. Furthermore, the proposed traffic allocation scheme makes use of serial M/M/1 queue model to analyze the transmission delay of traffic allocation in cooperation link with WPAN and WWAN. Therefore, the traffic distribution problem is concluded as non-linear programming with both equal and unequal constraints. Finally, the optimized traffic allocation result is solved out by Lagrange differential condition and K-T condition. Moreover, the open M/M/1 queuing system is proposed to analyze the traffic transmission delay in the scenario considering packet losing feature of radio networks.Radio resource is the only bearer of all services. As for the coordination of heterogeneous radio resources in multi-users scenario, an adaptive joint resource scheduling is proposed based on the integration of WLAN and cellular system. The proposed joint resource scheduling scheme adopts utility functions to evaluate the resource allocation of single-mode terminals and multi-mode terminals in cellular system and WLAN respectively, and it introduces fairness factor to make more traffics of multi-mode terminal be allocated to WLAN system, which to some extent can increase scheduling opportunity for single-mode terminal in cellular system. And the proposed resource scheduling scheme can effectively guarantee fairness between single-mode terminal and multi-mode terminal.A summary is given at the end, where the future research directions related to this dissertation are analyzed and investigated. |
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