Chen-Hua Shih

A cross-layer approach for real-time multimedia streaming on wireless peer-to-peer ad hoc network

Peer-to-peer (P2P) live streaming over mobile ad hoc network (MANET) is a state-of-the-art technique for wireless multimedia applications, such as entertainments and disaster recovery. The peers share the live streaming over MANET via multi-hop wireless link, so an efficient data delivery scheme must be required. However, the high churn rate and the frequent mobility baffle the P2P membership management and overlay maintenance. The unreliable wireless connection of MANET leads to the difficulties of large-scale and real-time streaming distribution, and a lack of overlay proximity leads to the inefficient streaming delivery. We present a cross-layer design for P2P over MANET to manage and maintain the overlay, and select efficient routing path to multicast media streams. Our proposed scheme (COME-P2P) integrates both P2P DHT-based lookup and IPv6 routing header to improve the delivery efficiency. Through the cross-layer design, the low layer detects mobility for informing high layer to refine the finger table, and high layer maintains the efficient multicast path for informing low layer to refine the routing table. How to keep stable routing paths for live streaming via IPv6 routing is the main contribution of this paper. The overlay proximity can shorten routing propagation delay, and the hop-by-hop routing can avoid the traffic bottleneck. Through the mathematical analysis and simulation results, COME-P2P can be demonstrated to achieve high smoothness and reduce signaling overhead for live streaming.

An aided congestion avoidance mechanism for TCP vegas

TCP Vegas detects network congestion in the early stage and successfully prevents periodic packet loss that usually occurs in TCP Reno. It has been demonstrated that TCP Vegas achieves much higher performance than TCP Reno in many aspects. However, TCP Vegas cannot prevent unnecessary throughput degradation when congestion occurs in the backward path, it passes through multiple congested links, or it reroutes through a path with longer round-trip time (RTT). In this paper, we propose an aided congestion avoidance mechanism for TCP Vegas, called Aid-Vegas, which uses the relative one-way delay of each packet along the forward path to distinguish whether congestion occurs or not. Through the results of simulation, we demonstrate that Aid-Vegas can solve the problems of rerouting and backward congestion, enhance the fairness among the competitive connections, and improve the throughput when multiple congested links are encountered.

A cross-layer middleware for context-aware cooperative application on mobile ad hoc peer-to-peer network

Mobile ad hoc peer-to-peer (P2P) applications become popular for providing the file sharing, voice communicating, and video streaming services due to entertainments and disaster recovery. However, both the topology of wireless network and the overlay of P2P network are dynamic, so the middleware is proposed to integrate such architectures of service-oriented applications. Therefore, we propose context-aware cooperative application (CACA) to overcome the frequent churn and high mobility problems. CACA proposes a cross-layer middleware to integrate DHT-based lookup, anycast query, and P2P delivery via the IPv6 routing header. Through anycast query, the response delay can be shortened and the query duplication can be minimized. Via IPv6 routing header, the delivery efficiency can be improved. Through the cross-layer design, the finger table in overlay layer is combined with the routing table in network layer to heighten proximity. The simulation results demonstrate that CACA has the outstanding performances of short download delay, high playback continuity, and low signaling overhead in mobile ad hoc network.

A proxy-based fast handover scheme for hierarchical mobile IPv6

With the advances of wireless technologies, how to efficiently offer users anytime, anywhere seamless Internet access is essential to a successful handover scheme. We propose a fast handover mechanism which introduces the idea of hierarchical network architecture into PMIPv6, to solve the problem that the MN encountered during handover in PMIPv6 domain; moreover, we introduce an additional buffering scheme to reduce packet loss and solve packet ordering problem. The simulation results show that seamless roaming can be achieved, and much better performance can be obtained than with the other literature approach.

Advanced bootstrap and adjusted bandwidth for content distribution in peer-to-peer live streaming

Today peer-to-peer (P2P) systems have been deployed for various Internet multimedia applications such as live video streaming service. However, both peer churn and upload capacity insufficiency are inherent problems causing long start-up delay and unstable playback quality. Therefore, we introduce a scalable application-layer multicast algorithm, ABCD-P2P, which inherits the short end-to-end delay and low control overhead due to the push delivery scheme. The logical overlay is close to the physical topology (i.e., geographic proximity) in ABCD-P2P, so a short streaming multicast delivery path reduces the number of hops and avoids the network bottleneck or far routing. Both an advanced bootstrap mechanism and an adjusted bandwidth mechanism are suitable for the asymmetric bandwidth network. The mathematical analysis and simulation results demonstrate that our proposed scheme can achieve the goals of high playback smoothness, short start-up delay, short end-to-end delay, low control overhead, and short recovery time.

RING: A Cross-Layer Design for Voice Communicating on P2P-MANET

RING: A Cross-Layer Design for Voice Communicating on P2P-MANET This paper presents RING, a novel peer-to-peer (P2P) voice communicating system on mobile ad hoc network (MANET). RING proposes a ring overlay, a set of protocols, and an implementation enabling the delivery voice among peers without connecting to Internet. The logical overlay is proximal to the physical topology based on cross-layer scheme, which detects the network dynamics and peer movement to support a communication with high delivery ratio. The ring overlay is used to utilize simply, stabilize real-time delivery, and minimize signaling overhead. The characteristics of self-organization and decentralization share the network load and help the network scalability for MANET. Although the traditional P2P system falls into impropriety and inefficiency of real-time distribution on MANET, RING can achieve the acceptable quality in short-term and small-scale purpose. We discuss the comparison of overlay performance and demonstrate that RING is workable via the mathematical theory and a series of experiences. RING can deal with peer arrival and departure quickly and simply to shorten the service interruption time with minimal signaling overhead.