【摘要】 在单播与多播混合服务的OFDM蜂窝系统中,因负载较重而使带宽资源被完全占用时,为接纳更多的多播用户,在单播多媒体用户可接受的范围内提出:基于信道容量平滑的QoS升降级带宽借用方法.通过建立QoS升降级的子载波借用模型和CUpDown-QoS算法,达到最大化多播用户数和减小多播切换呼叫中断率;提出了GoS保证下,限制新呼叫的动态带宽借用阈值,给出基于Markov模型的CBP(Call Blocking Probability)与HDP(Handoff Dropping Probability)最优折中的阈值确定方法,以及多播优先的动态带宽借用策略对阈值确定的影响.更多还原

【Abstract】 In an OFDM cellular system with unicast and multicast integrated services,in order to admit more multicast members when the bandwidth resource are all occupied because of heavy load,a scheme of borrowing enough bandwidth based on the channel capacity from unicast multimedia users’ smoothly upgrading or downgrading their QoS level within an accepted range is suggested.Maximizing the multicasting members and lowing multicasting handover dropping probability are realized by establishing a QoS upgrading/downgrading model of sub-carriers borrowed and proposed CUpDown-QoS algorithm.Farther on,a bandwidth threshold of dynamic bandwidth borrowing to limit new calls for a satisfied grade of service(GoS) is defined,and the optimized tradeoff of CBP and HDP is achieved by the method of decided the threshold based on the Markov model while the impact of dynamic bandwidth borrowing strategy to the threshold is obtained.更多还原