Abstract: The access strategy of heterogeneous network is closely related to the efficiency of network resource management; meanwhile, the network complexity and the competition of network resources directly affect the customer service quality. Aiming at the problem of high handover dropping rate and high call blocking probability, low resource utilization ratio in heterogeneous network admission control, this paper proposes a joint call admission control algorithm based on Markov chain. This admission control algorithm dynamically sets aside a certain bandwidth resources for handoff call service and real time service, and whether to release bandwidth is determined by bandwidth degradation factors setting according to different services; moreover, according to user preferences and Quality of Service（QoS） requirement of different services, this paper constructs the utility function of call admission control, established and analyzed by using Markov chain. The simulation results show that this algorithm improves the utilization of network resources, reduces the complexity of system, and meets the QoS requirements of various services.

Key words:  heterogeneous network, admission control algorithm, joint call, Markov chain, Quality of Service（QoS）

摘要： 异构网络的接入策略与网络资源管理效率紧密相关；同时，网络复杂性与网络资源竞争性直接影响到用户服务质量。针对异构网络接入控制存在的切换掉话率和呼叫阻塞率高、资源利用率低等问题，提出了基于马尔科夫链的联合呼叫接入控制算法。接入控制算法为切换呼叫业务、实时业务动态地预留了一定的带宽资源，根据不同业务设置带宽降级因子来决定是否释放带宽；同时，根据用户偏好和不同业务的QoS要求，构建了呼叫接入控制效用函数，利用马尔科夫链进行了建模分析。仿真表明，算法提高了网络资源利用率，降低了系统复杂度，满足了各类业务的QoS要求。

关键词: 异构网络, 接入控制算法, 联合呼叫, 马尔科夫链, 服务质量