| Popis: |
One of the recent trends in the telecommunication industry is the integration of voice and data services in wireless and mobile networks. In the face of this more complex traffic mix, where each service may have different requirements, providing quality of service (QoS) guarantees poses a difficult challenge for network service providers. Call admission control (CAC) and channel allocation can help satisfy these guarantees. The objective of this research is to develop resource allocation schemes in integrated wireless and mobile networks. Our research work demonstrates that resource borrowing is an effective approach to achieve these targets. Several resource allocation schemes with channel borrowing have been proposed. The channels in each cell are divided into two parts and pre-allocated for real-time and non-real-time services. One type of service is allowed to borrow unused channels from the other under certain conditions provided that the QoS of the latter is not significantly affected. We take advantage of the delay insensitivity of non-real-time services and allow real-time service calls to preempt non-real-time service calls. We model the system using the Markov process to understand the effects of channel borrowing on QoS for different types of traffic. Widely used CDMA systems are mainly interference limited and the transmit power is an important resource. In such systems, resource borrowing occurs in terms of power borrowing. Based on the current measure of the received power, we develop an algorithm to estimate the updated total received power due to a new call. Using this algorithm, we propose a total received power based CAC for integrated CDMA systems. The IEEE 802.16 media access control (MAC) layer is designed to support desired level QoS for different services. We present and analyze an adaptive resources allocation algorithm based on QoS degradation. Unlike the preemptive channel borrowing, service degradation allows the low priority service to free only part of its resource in favor of the high priority service. We observe that the degradation scheme outperforms the fixed rate scheme in terms of new call blocking probability, bandwidth utilization and transmission capacity. |
