近年來無線寬頻網路技術迅速發展以滿足人們隨時隨地上網的需求，同時提供更大 的頻寬和支持各種類型網路服務。為了讓更多的使用者上網並且維持系統上使用者的連線品質，無線允許進入控制機制(Radio Admission control)對資源的管理是一個重要的議題。 本研究在LTE無線接取網路環境下使用virtual partitioning(VP)的資源分配概念將各種類型的traffic 分成四個群組，並使用資源搶奪方式讓業者能依照需求提升特定服務類型的連線數量同時增加無線資源使用率。此外為避免系統接受過多連線導致現有連線在通道狀況變差時沒有足夠資源來滿足QoS，我們提出資源保留策略來防止連線因通道狀況變差而中斷的情形發生。因此系統會在考量所有連線通道狀況以及所需的QoS 後去預估系統剩餘可用資源以接受新連線建立。 依照提出之資源保留策略有最保守到最積極幾種方式，業者可依照希望提供給消費 者的連線品質而有不同選擇，最後結果顯示愈保守的資源保留方式能提供較好的連線品質，而較積極的方式則能提高系統資源使用率。The wireless broadband network technologies have been evolved rapidly to satisfy people’s requirement for the access anytime and anywhere. In order to support more users to share the wireless network resources and to maintain Quality of Service (QoS) of existing users, the Radio admission control (RAC) is an important issue toward effective resource utilization. This study adopts virtual partitioning (VP) model to allocate radio resource to divide multiclass services into several groups according to connection characteristics. These groups include the most conservative to the most positive types. By using preemption method to preempt other group’s resource, operators could promote the opportunity of specific services to build up bearer successfully according to their requirements and then increase resource utilization. To avoid eNB accepts too many bearers result in some exiting bearers could not satisfy QoS when their channel condition is downgraded, we propose a resource reservation method to achieve it. The proposed scheme considers the channel conditions of existing bearers and their QoS, to adjust resource reservation. And whether the new bearer can be admitted or not is decided by the calculated residual bandwidth. Furthermore, in addition to maintaining the minimum rate of the bearer, the proposed also estimates the effective residual bandwidth to allocate extra bandwidth for better transmission services. Exhaustive simulations were performed to examine the effectiveness of the proposed scheme in blocking rate, dropping rate, allocated bandwidth, etc.. And simulation results show that the proposed scheme illustrate good performance.
