一個隨意網路上跨層設計的通用同儕平台

Abstract

「行動隨意網路」不用任何網路基礎建設佈建，即可以發展隨取需求與自成結構的網路，因此行動隨意網路適合用於軍事、緊急救援、警消等艱困任務的環境，隨著行動隨意網路的發展，「同儕計算」已被論證為一種管理行動無線裝置的有效方法，這類的解法或網路架構稱為「行動隨意網路上的同儕管理系統」。然而截至目前為止，整合同儕應用服務與行動環境的網路架構仍然存在一些問題，例如：高度封包遺失率、缺乏跨層修復能力、低弱的服務持續性，這些缺點都會對這類網路架構造成不良的影響。而且目前的系統都只適合少數的客戶需要特定的服務，所以我們設計一個跨層演算法以解決上述的問題，並實作一個同儕計算平台來整合檔案分享與影音串流的應用服務，因為同時改善緩衝機制、排程演算法、跨層結構，這個同儕計算平台可支援高度擴充性與各式各樣的同儕軟體應用。 在這個研究中，跨層設計整合了同儕計算的跨層與路由連線的網路層，並且結合同儕轉傳路線與連點路由途徑，如此一來，我們的方法同時擁有路由表與指向表的資訊，加上使用第六版網際網路協定的行動路由特性，能夠達成跨層的鄰似性，這種鄰似性可以提高封包傳輸的成功率、跨層修復能力、服務的持續性。由於上面所提及的優點，我們稱此方法為「通用同儕行動隨意網路系統」，能夠降低封包傳輸的失敗率與網路流量負擔，進而提升服務品質。 首先，我們研究分析很多行動隨意網路上同儕管理系統的演算法，然後設計出所提的跨層體制，這是非常適合高度擴增性和多群體的使用者。第二，我們設計緩衝機制、排程演算法、跨層結構等元件，讓各種同儕分享軟體都能適用。第三，我們推導數學模組和理論公式來量化系統的延遲時間和負載量，用理論的分析評估所提方法效能的極限。最後，我們實作所提方法在網路模擬器上，論證模組與公式的正確性，經由模擬結果討論系統效能的改善程度，必且依照模擬結果調校參數，使得系統最佳化。 總而言之，我們提出跨層式的行動隨意網路搭載同儕管理協定，也就是通用同儕行動隨意網路系統，所有同儕分享軟體皆能適用。這套協定不僅能增進封包傳輸的成功率與跨層的修復能力，還能提高服務的持續性，使用很低的成本即能夠發展行動多媒體分享服務。

Mobile ad hoc network (MANET) can be employed to develop on-demand self-organized network without the support of infrastructure. Therefore, MANET is suitable for certain hard task forces, such as military, emergency rescue, and police. With the development of MANET, P2P solution has been demonstrated to be an efficient technique for the management of wireless ad hoc nodes. P2P-MANET (P2P over MANET) has appeared in this kind of network architecture. However, there are several problems in the integration of P2P applications and mobile environment so far. High packet loss rate, low recovery, and low continuity degrade the performance of P2P-MANET. Currently the existing system is only limited in a single requirement for few particular users. Therefore, we design a cross-layer algorithm to solve the above mentioned problems, and implement a P2P platform to integrate file sharing and media streaming. We improve the methods for buffer, scheduling, and overlay to establish a P2P platform for the high scalability and the support of various P2P applications. In this research, the cross-layer design integrates P2P overlay and routing layer, and combines P2P forwarding path and hop-by-hop routing path, such that there is the information of routing table in finger table. The characteristics of IPv6 mobile routing is used to achieve overlay proximity, which heightens packet delivery rate, recovery ability, and playback continuity. Due to above characteristics, we call the proposed scheme Generic P2P-MANET System (GPMS). GPMS can reduce both packet failure rate and traffic overhead, which in turn improve quality of service. First, we survey P2P-MANET algorithms, and design the cross-layer scheme, which is suitable for high scalability and large group of users. Second, we design the buffer, scheduling, and overlay, which is adaptable for all P2P cooperation. Third, we derive the mathematical model or theoretical formula to evaluate latency and overhead. Therefore, we can evaluate the limitation and basis of the performance. Finally, we use a network simulator, OMNet++, to demonstrate the correctness of model and formula. And we configure the parameters and optimize the proposed algorithms depending on the simulation results, which are used to discuss the performance and improvement. In summary, we propose a cross-layer P2P-MANET protocol, GPMS, which is suitable for all P2P content sharing applications. The proposed scheme can improve packet delivery rate, recovery ability, and playback continuity to develop a media sharing service on mobile environment with affordable cost.