全光都會網狀/環狀骨幹及其互聯之光纖及無線擷取網路整合技術---子計畫五：在高速移動性下多模無線存取網路架構中之品質服務技術研究設計

Abstract

隨著無線網路技術的快速發展，各種無線擷取服務也隨之成長，例如 WiFi multimedia 以及網路 遊戲等。雖然在現今的無線網路環境之下已經可以成功的支援這些服務，但是當使用者在此無線 網路中移動時，其效能卻不盡理想。造成這個結果最主要的原因是由於WiFi 無線網路本身的涵 蓋範圍不夠廣，對於漫遊時的各種需求(特別是在服務品質方面)也沒有一個有效率的機制來管理。 WiMAX 為一種支援固定及行動存取的寬頻無線技術，其所涵蓋的範圍可多達數公里遠。WiMAX 目前制訂了兩種版本：IEEE 802.16-2004 以及IEEE 802.16e，前者適用於固定點存取，後者則支 援了移動性的存取。至於異質網路間之Handover，正在製訂中之IEEE 802.21 標準將會有規範。 由於無線網路無法像行動電話網路般有較廣的覆蓋範圍，故當使用者在移動時想維持連接性 相對的來說就較為困難，更別提要達到QoS 的功能了。在這個計畫中，我們試圖研究發展一個 在MIMO(Multiple-Input Multiple-Output) 多模式無線存取無線技術下可支援QoS 以及行動性的 方法，並可以透過WiMAX來達成。藉由MIMO，在IEEE 802.16e 下的行動使用者能用soft handover 來在cell 之間傳輸，甚至在異質的網路間互傳，例如從WiFi 到WiMAX。故在handover 期間可 維持點對點的連通性以及Service Level Agreements (SLAs)。我們將擴展當前在WLAN 行動性的 研究到多模存取網路，並且研究跨網路間的soft handoff，這些可能包含了QoS routing，buffering 以及traffic 分類控制等。並於第二、三年使用市場上所提供的組件來實現系統模組。

Study and Design of QoS Techniques over Multimode Wireless Access Networks with High Mobility The fast technology advance in wireless networks leads to the quick growth in wireless application services, such as WiFi multimedia and Internet games. Although nowadays these kinds of services can be deployed successfully in wireless LAN environment, however, these services still could not be support satisfactorily if the wireless client is in motion. This is due to the deficiency in coverage of wireless LAN as well as the lack of an effective mechanism which can fulfill the complex requirements for roaming, especially regarding the Quality of Services (QoS). WiMAX is a broadband wireless technology that supports fixed, nomadic, portable and mobile access, with none-line-of-sight coverage radius of several miles. Two versions of WiMAX have been defined: IEEE 802.16-2004 and IEEE 802.16e, the former is optimized for fixed and nomadic access, while the latter will support portability and mobility. Regarding the handover across heterogeneous networks, the IEEE 802.21 standard is undergoing and it will define the specification. Since the cell of wireless LAN is too small to achieve as wide coverage as cellular mobile does, it is difficult to maintain connectivity once a mobile client is moving, not mention the QoS. In this proposal, we will investigate the support of QoS and mobility based on a multimode wireless access infrastructure (WiMax/WiFi/Cellular), with MIMO (Multiple-Input Multiple-Output) radio techniques, which is very likely to be used in WiMax. With MIMO, mobile client based on the IEEE 802.16e could perform soft handoff, which is a make-before-break mechanism, to transit from a cell to another one, or even from one type of network such as WiFi to another one such as WiMax, therefore the end-to-end connectivity as well as the service quality, such as Service Level Agreements (SLAs) could be maintained during handoffs. We will extend our current study of mobility based on WLANs to multimode access networks, and investigate the cross-network soft handoff, which may include QoS routing, buffering, and traffic classification and control. We will also prototype the system module at the second and third years based on the components available on the market.