Improving the performance of QoS models in MANETs through interference monitoring and correction

Mobile Ad hoc Networks (MANETs) have been proposed for a wide variety of applications, some of which require the support of real time and multimedia services. To do so, the network should be able to offer quality of service (QoS) appropriate for the latency and throughput bounds to meet appropriate real time constraints imposed by multimedia data. Due to the limited resources such as bandwidth in a wireless medium, flows need to be prioritised in order to guarantee QoS to the flows that need it. In this research, we propose a scheme to provide QoS guarantee to high priority flows in the presence of other high as well as low priority flows so that both type of flows achieve best possible throughput and end-to-end delays. Nodes independently monitor the level of interference by checking the rates of the highest priority flows and signal corrective mechanisms when these rates fall outside of specified thresholds. This research investigates using simulations the effects of a number of important parameters in MANETs, including node speed, pause time, interference, and the dynamic monitoring and correction on system performance in static and mobile scenarios. In this report we show that the dynamic monitoring and correction provides improved QoS than fixed monitoring and correction to both high priority and low priority flows in MANETs

Supporting Service Differentiation with Enhancements of the IEEE 802.11 MAC Protocol: Models and Analysis

As one of the fastest growing wireless access technologies, Wireless LANs must evolve to support adequate degrees of service differentiation. Unfortunately, current WLAN standards like IEEE 802.11 Distributed Coordination Function (DCF) lack this ability. Work is in progress to define an enhanced version capable of supporting QoS for multimedia traffic at the MAC layer. In this paper, we aim at gaining insight into three mechanisms to differentiate among traffic categories, i.e., differentiating the minimum contention window size, the Inter-Frame Spacing (IFS) and the length of the packet payload according to the priority of different traffic categories. We propose an analysis model to compute the throughput and packet transmission delays. In additions, we derive approximations to get simpler but more meaningful relationships among different parameters. Comparisons with discrete-event simulation results show that a very good accuracy of performance evaluation can be achieved by using the proposed analysis model

Influence of distortions of key frames on video transfer in wireless networks

In this paper it is shown that for substantial increase of video quality in wireless network it is necessary to execute two obligatory points on modernization of the communication scheme. The player on the received part should throw back automatically duplicated RTP packets, server of streaming video should duplicate the packets containing the information of key frames. Coefficients of the mathematical model describing video quality in wireless network have been found for WiFi and 3G standards and codecs MPEG-2 and MPEG-4 (DivX). The special experimental technique which has allowed collecting and processing the data has been developed for calculation of values of factors.Comment: 6 pages, 4 figures, 2 Table

Random Linear Network Coding for 5G Mobile Video Delivery

An exponential increase in mobile video delivery will continue with the demand for higher resolution, multi-view and large-scale multicast video services. Novel fifth generation (5G) 3GPP New Radio (NR) standard will bring a number of new opportunities for optimizing video delivery across both 5G core and radio access networks. One of the promising approaches for video quality adaptation, throughput enhancement and erasure protection is the use of packet-level random linear network coding (RLNC). In this review paper, we discuss the integration of RLNC into the 5G NR standard, building upon the ideas and opportunities identified in 4G LTE. We explicitly identify and discuss in detail novel 5G NR features that provide support for RLNC-based video delivery in 5G, thus pointing out to the promising avenues for future research.Comment: Invited paper for Special Issue "Network and Rateless Coding for Video Streaming" - MDPI Informatio

Network Utility Maximization under Maximum Delay Constraints and Throughput Requirements

We consider the problem of maximizing aggregate user utilities over a multi-hop network, subject to link capacity constraints, maximum end-to-end delay constraints, and user throughput requirements. A user's utility is a concave function of the achieved throughput or the experienced maximum delay. The problem is important for supporting real-time multimedia traffic, and is uniquely challenging due to the need of simultaneously considering maximum delay constraints and throughput requirements. We first show that it is NP-complete either (i) to construct a feasible solution strictly meeting all constraints, or (ii) to obtain an optimal solution after we relax maximum delay constraints or throughput requirements up to constant ratios. We then develop a polynomial-time approximation algorithm named PASS. The design of PASS leverages a novel understanding between non-convex maximum-delay-aware problems and their convex average-delay-aware counterparts, which can be of independent interest and suggest a new avenue for solving maximum-delay-aware network optimization problems. Under realistic conditions, PASS achieves constant or problem-dependent approximation ratios, at the cost of violating maximum delay constraints or throughput requirements by up to constant or problem-dependent ratios. PASS is practically useful since the conditions for PASS are satisfied in many popular application scenarios. We empirically evaluate PASS using extensive simulations of supporting video-conferencing traffic across Amazon EC2 datacenters. Compared to existing algorithms and a conceivable baseline, PASS obtains up to $100\%$ improvement of utilities, by meeting the throughput requirements but relaxing the maximum delay constraints that are acceptable for practical video conferencing applications

User behaviour modelling for resource management in a hybrid UMTS/DVB-T network

Third generation mobile networks such as UMTS are designed to enhance the deployment of multimedia services providing high data rates and new flexible communication capabilities. However, these systems are interference limited and as such their performance is lowered in the case of a large number of users generating heavy traffic. A solution to this problem is to interconnect the UMTS network to a Digital Video Broadcasting-Terrestrial (DVB-T) network, so that the lack of capacity of UMTS during busy periods can be offset by the high bit rate available on the broadcast network. In order to justify this choice a prediction of the number of subscribers requesting the new multimedia applications designed for this scenario is needed. This paper focuses on the user behaviour modelling for multimedia services in a hybrid UMTS/DVB-T platform. The aim of the paper is to provide operators with a forecast of the demand for new multimedia services showing how they can be subject to a very high number of subscriptions, which UMTS would hardly be able to handle

An Energy and Performance Exploration of Network-on-Chip Architectures

In this paper, we explore the designs of a circuit-switched router, a wormhole router, a quality-of-service (QoS) supporting virtual channel router and a speculative virtual channel router and accurately evaluate the energy-performance tradeoffs they offer. Power results from the designs placed and routed in a 90-nm CMOS process show that all the architectures dissipate significant idle state power. The additional energy required to route a packet through the router is then shown to be dominated by the data path. This leads to the key result that, if this trend continues, the use of more elaborate control can be justified and will not be immediately limited by the energy budget. A performance analysis also shows that dynamic resource allocation leads to the lowest network latencies, while static allocation may be used to meet QoS goals. Combining the power and performance figures then allows an energy-latency product to be calculated to judge the efficiency of each of the networks. The speculative virtual channel router was shown to have a very similar efficiency to the wormhole router, while providing a better performance, supporting its use for general purpose designs. Finally, area metrics are also presented to allow a comparison of implementation costs