标题: | IEEE 802.11 无线区域网路品质保证之柔性允入控制机制 Soft-Guarantee-based Call Admission Control for IEEE 802.11 Wireless LANs |
作者: | 林士勋 Shih-Hsun Lin 杨启瑞 Maria C. Yuang 资讯科学与工程研究所 |
关键字: | 竞入控制;允入控制;柔性保证;服务品质;Contention Control;Call Admission Control;Soft Guarantee;Quality of Service |
公开日期: | 2003 |
摘要: | 随着科技的演进,无线网路传输速率亦逐渐成长。因此,无线多媒体沟通的需求也随之增加。IEEE 802.11媒体存取控制机制是目前用于无线区域网路相当常见的方式。但是,此方法对于多媒体通讯并不提供讯务之品质保证(例如:音讯传输)。另一方面,允入控制机制也是另一种重要的方法。允入控制主要用于维持已连通知多媒体连结之品质,避免新进入之连结破坏原有的保证。在此,我们希望结合媒体存取控制与允入控制机制两种概念,建立出一套整合性的演算法Soft-Guarantee-Based Call Admission Control (SCAC),以提供柔性允入控制。此演算法主要着眼于提供音讯连结品质上的保证并提高整体无线空间的使用率。SCAC包含三个主要的元件:QoS-enabled Call Admission Control (Q-CAC),Efficient Contention Control Algorithm (ECCA),and Resource Management Database (RMDB)。以旧有连结的品质要求为基础, Q-CAC搜寻事先建立好的资料库(RMDB),计算出对应的参数用以限制参与竞争的MT数量,并保证原有连结的品质需求。ECCA采用两阶段之演算法已提供音讯较佳之竞入控制。透过模拟实验结果,我们可以证明SCAC能够提供系统事先定义之柔性保证程度(例如:99%品质保证)于音讯连结,同时提供较佳的竞入控制机制给紧急的讯务。 With the advent of new broadband technologies providing higher user data rate, the wireless communication is clearly poised for rapid growth. IEEE 802.11 MAC protocol is the most common method used in Wireless LANs (WLANs) with poor QoS guarantee for higher priority traffic such as voice signaling requests. On the other way, call admission control (CAC) method is also important for maintaining the QoS guarantees of communications in AP’s polling table. In this paper, we combine the concepts of CAC and MAC to construct a complete algorithm called Soft-Guarantee-Based Call Admission Control (SCAC) method. This method focuses on supporting QoS guarantee for voice traffic. SCAC has three major components: QoS-enabled Call Admission Control (Q-CAC), Efficient Contention Control Algorithm (ECCA), and Resource Management Database (RMDB). Based on demands of MTs in AP’s polling table, Q-CAC limits the contending MTs with voice signaling requests for maintaining QoS of voice connections in AP’s polling table by searching pre-constructed RMDB. ECCA adopts two phases algorithm by improving Contention Control (CC) concept to provide better contention resolution mechanism for high priority traffic. Simulation results demonstrate that SCAC can support pre-defined soft QoS guarantee (ex: 99% QoS guarantee) for voice traffic and provide lower contending time for high priority traffic such as voice signaling traffic. |
URI: | http://140.113.39.130/cdrfb3/record/nctu/#GT009117556 http://hdl.handle.net/11536/49968 |
显示于类别: | Thesis |
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