臺灣博碩士論文加值系統

由於行動通訊技術的快速成長，手機普及率和使用率也相對的提高，而系統服務提供者（Service Provider）必須針對使用者所要求的服務品質做一相當程度的保証（QoS）。對使用者來說，換手連線阻斷率（Handoff call dropping rate）及全新連線阻斷率（New call blocking rate）是使用者衡量系統服務品質的二大指標，而換手連線比全新連線擁有較高的優先權。對系統服務提供者來說，系統資源使用率（Channel utilization）將影響所能賺取的利潤。因此在這一篇論文中，我們將模擬現實環境中使用者的移動行為及針對以上三項指標提出一套預留頻寬（Channel reservation）及允許連線控制（Call admission control）的機制。
我們模擬現實交通環境中的道路及交通號誌來做為實驗的移動模型（Mobility model），使用者在道路上行進並且在交叉路口時隨機的遭遇紅燈而停留一段時間。此外，我們假設使用者之手機具有全球定位（GPS）的功能，因此根據使用者的位置、速度和方向，再配合道路地圖的分佈資訊，我們定時的預測使用者未來的位置並事先在使用者可能抵達的蜂巢（Cell）下預留所需的頻寬，因而減少當使用者移動到另一個蜂巢時由於資源不足而導致通訊中斷的機率，同時也可以提高系統整體的使用率。

Channel reservation techniques have been widely studied in cellular networks in order to meet the desired Quality of Service (QoS) requirements. In this paper, a distributed predictive channel reservation scheme, called the road-map-based channel reservation scheme (RMCR), and a call admission control algorithm are proposed. The goal is to reduce the handoff dropping probability and to improve the bandwidth utilization. In the RMCR scheme, we assume that the base stations are equipped with road-map information and that the mobile stations are equipped with Global Position System (GPS) devices. The mobile stations periodically report their GPS location information to their base stations. Based on the location information of the mobile stations at two consecutive epochs, the base stations estimate the speed and the moving direction of the mobile stations. Furthermore, the base stations estimate the probability that the mobile stations enter the neighboring cells based on their velocity and the road-map information stored in the base stations. The base stations then compute the amount of bandwidth to be reserved based on this probability. With the road map information, the base stations can make more accurate prediction on the users' mobility and hence reduce unnecessary bandwidth reservations.

Introduction
Assumption and Mobility Model
Road-map-based Channel Reservation
Distributed Call Admission Control
Reference

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