Ahmed Abd El Al

LS-SCTP: a bandwidth aggregation technique for stream control transmission protocol

Stream Control Transmission Protocol (SCTP) specifications utilize the multiple paths capabilities between the sender and receiver for retransmission of lost data chunks and as a backup in case of primary path failure. Under normal conditions, all data chunks are sent on the primary path chosen by the SCTP user during the transport connection initiation. In this paper, we address in detail various aspects related to extending and engineering SCTP in order to utilize the available paths for simultaneous transmission of data chunks, while maintaining the SCTP congestion control on each path so as to ensure fair integration with other traffic in the network. The extended SCTP, referred to as Load-Sharing SCTP (LS-SCTP), is able to aggregate the bandwidth of all the active transmission paths between the communicating endpoints. LS-SCTP monitors the paths, and accordingly it chooses the paths that are suitable for load sharing. LS-SCTP retransmission mechanism accelerates the delivery of missing data to the receiver in order to prevent stalling the transport connection while waiting for missing data chunks. Simulation results show that LS-SCTP is extremely beneficial for networks with limited bandwidth, high loss rate and failure prone links.

Unequal error protection for real-time video in mobile ad hoc networks via multi-path transport

In this paper, we propose a mechanism that combines retransmission-based error control with multi-path transport (MPT), to provide different levels of protection to real-time video in ad hoc networks. The mechanism factors in the importance of the retransmitted packets to the reconstructed video quality as well as the end-to-end latency constraints to minimize the overhead and maximize the reconstructed video quality at the receiver. Simulation results show that the proposed retransmission mechanism maintains the video quality under different loss rates and mobility speeds, with less overhead compared to error control methods that depend on controlling the intra-update rate. In addition, the mechanism is shown to be more robust to wireless losses and mobility than schemes that combine layered and multiple description coding with multi-path transport.

Bandwidth aggregation in stream control transmission protocol

In this paper, we address various aspects related to extending and engineering stream control transmission protocol (SCTP) to utilize its multi-homing support for simultaneous transmission of data chunks on different path, while maintaining the congestion control on each path to ensure fair integration with other traffic in the network. The extended SCTP, referred to as load sharing-SCTP (LS-SCTP), is able to aggregate the bandwidth of all the active transmission paths between the communicating endpoints. It monitors the paths, and accordingly chooses the paths that are suitable for load sharing. In addition, LS-SCTP retransmission mechanism accelerates the delivery of missing data to the receiver to prevent stalling the transport connection while waiting for missing data chunks. Simulation results show that LS-SCTP is extremely beneficial for networks with limited bandwidth and failure prone links.

Improving interactive video in wireless networks using path diversity

The increase in the bandwidth of wireless channels and the computing power of mobile devices increase the interest in video communications over wireless networks. However, the high error rate and the rapidly changing quality of the radio channels can be devastating for the transport of compressed video. In motion compensated coding, errors due to packet losses are propagated from reference frames to dependant frames causing lasting visual effects. In addition, the bounded playout delay for interactive video limits the effectiveness of retransmission-based error control. In this paper, we propose a mechanism that combines retransmission-based error control with path diversity in wireless networks, to provide different levels of protection to packets according to their importance to the reconstructed video quality. We evaluated the effectiveness of the mechanism under different network conditions. Simulation results show that the mechanism is able to maintain the video quality under different loss rates, with less overhead compared to error control techniques that depend on reference frame updates.

Collaborative content caching algorithms in mobile ad hoc networks environment

In this paper, we address the problem of collaborative video caching in ad hoc mobile networks. We consider network portraying static video server with wired interface to gateway node that is equipped with wireless interfaces, other nodes are requiring access to the video streams that is stored at video server. In order to reduce the average access latency as well as enhance the video accessibility, efficient video caching placement and replacement strategies are crucial at some of the distributed intermediate nodes across the network. Virtual backbone caching nodes will be elected by executing caching placement algorithm after running the routing protocol phase. The simulation results indicate that the proposed collaborative aggregate cache mechanism can significantly improve the video QoS in terms of packet loss and average packet delay.

A cross-layer optimized error recovery mechanism for real-time video in ad-hoc networks

The increase in the bandwidth of wireless channels and the computing power of mobile devices increase the interest in video communications over ad-hoc wireless networks. However, the high error rate and the rapidly changing quality of the radio channels can be devastating for the transport of compressed video. In addition, the bounded playout delay for interactive video limits the effectiveness of retransmission-based error control. In this paper, we propose an error recovery mechanism for real-time video that combines forward error correction (FEC), and multi-path retransmission. Based on the sender to receiver route obtained from lower layers, as well as the video data content, the mechanism determines the allocation of error correction code, as well as the retransmission criteria. We evaluated the effectiveness of the mechanism under different network conditions. Simulation results show that the proposed hybrid error recovery mechanism maintains the video quality under different loss rates and mobility speeds, with less overhead compared to error recovery methods that depend only on fixed FEC allocation

Supporting Real-Time Video in SCTP Networks

In this paper, we present adaptation strategies for realtime video streams over stream control transmission protocol (SCTP), where we switch among several versions of the coded video to match the available network bandwidth accurately, and meet client delay constraints. By monitoring the application buffer at the server, we estimate the current and future server buffer drain delay, and derive the transmission rate to minimize client buffer starvation. We also show that the adaptation accuracy can be significantly improved by a simple scaling to SCTP send-buffer size. The proposed mechanisms were evaluated through simulation and real Internet traces. Performance results show that the adaptation mechanism is responsive to bandwidth fluctuations, while ensuring that the client buffer does not underflow, and that the quality adaptation is smooth so that the impact on the perceptual quality at the client is minimal

High throughput path selection for multi-path video streaming in Ad-hoc networks

Owing to the absence of any static structure, ad-hoc networks are prone to packet losses and link failures. Selecting the shortest path may not lead to high quality routes. The consequent high loss rates can lead to the degradation of throughput and increase in the end-to-end delay on the selected path, which can lead to devastating effects for the transport of compressed video. This paper suggests a selection mechanism for multi-path routing protocols that selects routes on the basis of the expected throughput of the candidate routes. We have studied the performance of the proposed mechanism by incorporating it into a multi-path routing protocol, and examining the quality of compressed video streams in this network. Simulation results show that the proposed selection mechanism maintains the video quality under different loss rates and mobility speeds. Also we have found that our mechanism significantly outperform shortest path selection.