抢占式OVSF码动态分配算法

Preemptive dynamic assignment of OVSF codes

为了提高WCDMA(wideband code divisionmultiple access)系统中高优先级业务的接入率,提出一种基于优先级的抢占式OVSF(orthogonal variable spreadingfactor codes)码动态分配算法。该算法中,当新的高优先级业务呼叫到达时,若出现容量阻塞,则中断代价最小的低优先级业务,并将其占用的码字分配给高优先级业务;若出现码阻塞,则选择代价最小的码树进行码字重分配。应用MATLAB软件完成的仿真结果表明:在高负载的情况下,与传统动态码分配算法相比,本算法中高优先级业务的接入率能提高20%以上,同时算法保证了低的中断业务数和重分配码数,能良好地支持业务的QoS(quality of service)要求。

A priority-based preemptive dynamic assignment algorithm of orthogonal variable spreading factor （OVSF） codes was developed to improve the access probability of high-priority services in wideband code division multiple access （WCDMA） system. In this algorithm, when a new high-priority call arrives, the low-priority service with the lowest cost is interrupted and the code occupied by this service is assigned to the high-priority service if capacity blocking occurs. The code sub-tree with the lowest cost is reassigned to accept the new service if code blocking occurs. MATLAB simulations show that compared with conventional dynamic code assignment, the algorithm improves the access probability of high-priority services by more than 20% for high system loads. Additionally, the algorithm guarantees a smaller number of interrupted services and reassigned codes, so it improves the quality of various services.