Research On System Capacity And Resource Management Algorithms In Wireless Cellular Networks

Wireless mobile communication system, represented by wireless cellular networks, is a milestone in the history of wireless communication technology. In order to support people to mutually communicate in any form of information resources, there are various issues have to be carefully examined in Wireless Cellular Networks, such as providing QoS guarantee for multi-service. One of the key elements in providing QoS guarantee for multi-service is an effective Resource Management Strategy. The lack of available radio resources, the scarcity and extreme fluctuation of available link bandwidth, the user mobility and frequent handoffs, and various characteristics of different services in the wireless cellular networks makes providing QoS guarantee for multi-service a very tough task. As the widely deploying of mobile applications, the demand for providing multi-service in wireless cellular networks becomes more imperative. The next generation of networks is expected to eventually carry multimedia traffic-voice, video, images, or data, or combinations of them. Since different traffic has diversified QoS and radio resource requirements, multi-service Resource Management Strategy not only has to ensure that the network meets the QoS requirements of different applications, but at the same time has to fully utilize the scarce wireless resources (system capacity, bandwidth, or power) available in the wireless cellular networks. This dissertation studies the capacity performance of the multi-service wireless cellular networks and other key radio resource management algorithms-bandwidth allocation scheme and call admission control algorithm.Chapter 2 of this dissertation reveals that the mobility influences on the capacity-related parameters in wireless cellular networks are conspicuous. Due to the complex nature, there does not seem to exist a simple linear relationship between mobility and capacity. To the best of the author's knowledge, there has been so conclusive study on mobility and capacity for wireless cellular networks. As the statistics of the signals received by the mobile users from different base stations is hard to gain, whether to the user equipment (UE) or the basestation (Node B), computer simulation is used to study the mobility influences on capacity in wireless cellular network. The propagation model, the mobility model and traffic model are established in chapter 2, with concerns of guarded channel (GC) mechanism, handoff criterions and a simple power control algorithm, and some simplified or idealized assumptions adopted in current literatures are improved to better sketch the characterizations of practical system. The conclusion derived in this chapter could be utilized for dynamically adjusting the configuration parameters providing QoS guarantee and the reservation threshold of GC mechanism for handoff connections in wireless cellular network, which could improve the system performance, system capacity and the utilization of radio resource.Chapter 3 of this dissertation studies the multi-service Bandwidth Allocation Scheme algorithm (BAS). The system designing of next generation wireless cellular networks employing pico-cell will make handoff occurring much more frequently, which makes it more difficult to provide QoS guarantee for multi-service during handoff period, with concerning various characteristics of different services in the wireless cellular networks. The multi-service Bandwidth Allocation Scheme algorithm (BAS) for adaptive multimedia services is proposed in this chapter. In order to fully utilize the system resources, degrading the QoS of existing multimedia traffic in a controlled manner has been shown as an effective way to improve the overall system performance. However, compensation mechanisms are seldom considered in the literatures. One of the characteristic of the proposed multi-service BAS for adaptive multimedia services is the employment of the degradation policy and compensation mechanism. The performance analytical upper bounds of the proposed algorithm are also deduced in this section, with the numerical simulation results. In order to fully study the performance of multi-service BAS, four new QoS parameters related to multi-service BAS are defined. The numerical simulation results of the system performance parameters considered in this section-New Call Blocking Probability (P_b) and Handoff Call Dropping Probability (P_d) and system overall Bandwidth Utilization Rate (BUR)-show that the proposed algorithm outperforms other algorithms in the literature, in that it could not only fulfills the QoS requirement of different applications, but also efficiently utilizes the scarce radio resources in the system. Furthermore, this chapter also conducts computer simulation to demonstrate the performances of the new QoS parameters related to multi-service BAS and their impacts on the system performance, which will help us to better understand the nature of the performance of adaptive multimedia service, and improve the utilization of radio resources in wireless cellular networks.Chapter 4 of this dissertation studies the multi-service Call Admission Control algorithm (CAC). Admitting more users than the capacity into system will make the already admitted users suffer a loss of QoS, especially for the newly coming multi-service call, when the cell capacity and radio resources are depleted. Chapter 4 presents corresponding Call Admission Control (CAC) algorithms for different multi-service, including CAC algorithm for the basic layer (CAC_B), CAC algorithm for the enhancement layers (CAC_E), and CAC algorithm for non real-time data services (CAC_D). In order to valid the proposed multi-service CAC algorithms, computer simulations are carried out due to different scenario of the deployment phases of wireless cellular networks supporting adaptive multimedia service. The simulation results will benefit the system designing and planning of wireless cellular networks based on the characteristic of adaptive multimedia service and user mobility, as well as help dynamically adjusting the configuration parameters providing QoS guarantee, improving the utilization of radio resources, balancing the load of the system and ensuring the rational fairness among all users.Chapter 5 of this dissertation summarizes the simulation software. Simulation software is developed to verify and evaluate the proposed algorithms in this dissertation. All of the proposed radio resource management algorithms and the performance analysis are based on a wireless cellular network simulation platform. Chapter 5 presents the main frame of the simulation platform, the main parts of the software flow diagram and some of the selected codes. Chapter 6 of this dissertation concludes this dissertation, presents some suggestions for future research on some issues.