802.16網路的品質服務保證架構之設計

Broadband Wireless Access(BWA)的技術提供了更高速、更便利及無線上網的服務，也開啟了無線網路的新世代。IEEE 802.16 發展團隊於1998年推出了新的Wireless MAN標準，因而可以在長距離的無線網路傳輸提供高達134Mbps的頻寬，突破以往無線網路頻寬的限制。而在IEEE 802.16 PMP (Point to Multi-Point)的架構由Base Station (BS)來作中央管理者，而其它的Subscriber Stations (SSs)直接與BS連線；另一種802.16 Mesh mode中SS除了直接與BS連接，也可以讓SS彼此互連，因此在802.16 Mesh的架構之下BS與SS如何分工合作更顯重要。而在IEEE 802.16 MAC layer中data transmission必須透過time slot的分配來進行，因此在802.16 PMP的架構下如何妥善的作到slot allocation及資料在L3與L2不同層之間QoS類別的對應、封包切割與重組，如果沒有加以訂定將會影響多媒體服務的傳輸效能。此外在傳統的802.16 Mesh有centralized and distributed兩種scheduling mode，然而centralized scheduling中BS如同cluster head，可以直接進行time slot管理及分配，但是traffic flow必須彙集於BS後，再決定如何進行data transmission也造成傳遞上的不經濟；distributed scheduling在資料傳遞的路徑上能作到較佳的選擇，但是為了達成這個目標，標準中訂定必須靠SS之間進行contention以取得time slot分配的相關資訊，也因而造成嚴重signal overhead。基於以上提到的問題，在我們的博士論文中，針對IEEE 802.16 PMP及Mesh兩種網路模式，分別提出整合型QoS架構，以期降低傳送的延遲及提昇傳送效能，並且也希望進一步降低整個802.16無線網路上的signal overhead，最終目標將提出一個高效能的整合架構運作於IEEE 802.16 PMP及Mesh無線網路之上。

關鍵字

802.16 ； WiMax ； PMP ； Mesh ； QoS ；服務品質保證

並列摘要

Since 1998, IEEE 802.16 working group has launched a standardization process called Wireless Metropolitan Area Network (Wireless MANTM) for BWA. The most updated specification of 802.16 (IEEE Std 802.16d-2004) focuses on fixed location wireless access and supports up to 134 Mbps data rate. The PMP (Point to Multipoint) configuration of IEEE 802.16 network consists of a base station (BS) and a couple of subscriber stations (SS) that connect to the BS via high-speed wireless link. The BS acts as a gateway to the Internet. Legacy LANs or even more complex subnet systems can connect to the IEEE 802.16 network via SS. An IEEE 802.16 network (including the Legacy LANs that connect to the SS) can cover a large geographical area since the distance between the BS and the SS can be up to 30 miles. The other mode is 802.16 Mesh configuration provides that there is no need to have direct link from subscriber stations (SS) to the base station (BS) and a node can choose the links and path with best quality to transmit data and avoid the congested area. To provide better QoS service over the 802.16 network, layer 3 (L3) and layer 2 (L2) QoS services must be integrated. Therefore, cross-layer mechanisms are designed in our proposed IEEE 802.16 QoS frameworks. In this dissertation, we try to propose the QoS frameworks for multimedia transmission in the IEEE 802.16 PMP and Mesh network respectively. Both of the two frameworks could increase the performance of throughput and reduce the overhead of delay.

並列關鍵字

802.16 ； WiMax ； PMP ； Mesh ； QoS

參考文獻

[1] IEEE Std 802.16-2004, “IEEE Standard for Local and Metropolitan Area Networks--Part 16: Air Interface for Fixed Broadband Wireless Access Systems,” Oct. 2004.

Google Scholar

[2] IEEE Std 802.16e-2005, “IEEE Standard for Local and Metropolitan Area Networks--Part 16: Air Interface for Fixed Broadband Wireless Access Systems--Amendment 2: Physical and Medium Access Control Layers for Combined Fixed and Mobile Operation in Licensed Bands,” Feb. 2006.