Supporting Multimedia Applications Research Articles

Network Condition-Aware Enhanced Distributed Channel Access for IEEE 802.11e Wireless Ad-Hoc Networks

Abstract The increasing use of multimedia applications in wireless ad-hoc networks makes the support of quality of service (QoS) an overriding necessity. In this article, we present a new extension of the IEEE 802.11e EDCA scheme called NCA-EDCA, which uses the lifetime and the number of retransmissions attempts of a packet to assess the aggressiveness of the environment in order to adjust the channel access parameters to work in the best possible way and improve service quality accordingly. This new extension aims to (1) improve the performance of real-time applications; (2) increase the overall throughput by reducing the collision rate and (3) achieve an acceptable level of fairness. The simulation results show that our extension significantly improves EDCA for better QoS support of multimedia applications. More specifically, it increases throughput of the different flows by no negligible factors and significantly reduces the collision rate while maintaining a high degree of fairness between flows of equal priority.

Quality of experience enhancement of high efficiency video coding video streaming in wireless packet networks using multiple description coding

Recently, video streaming has attracted much attention and interest due to its capability to process and transmit large data. We propose a quality of experience (QoE) model relying on high efficiency video coding (HEVC) encoder adaptation scheme, in turn based on the multiple description coding (MDC) for video streaming. The main contributions of the paper are (1) a performance evaluation of the new and emerging video coding standard HEVC/H.265, which is based on the variation of quantization parameter (QP) values depending on different video contents to deduce their influence on the sequence to be transmitted, (2) QoE support multimedia applications in wireless networks are investigated, so we inspect the packet loss impact on the QoE of transmitted video sequences, (3) HEVC encoder parameter adaptation scheme based on MDC is modeled with the encoder parameter and objective QoE model. A comparative study revealed that the proposed MDC approach is effective for improving the transmission with a peak signal-to-noise ratio (PSNR) gain of about 2 to 3 dB. Results show that a good choice of QP value can compensate for transmission channel effects and improve received video quality, although HEVC/H.265 is also sensitive to packet loss. The obtained results show the efficiency of our proposed method in terms of PSNR and mean-opinion-score.

Saturation Throughput Analysis of the IEEE 802.11e EDCA Network with Contention Free Burst Under Fading Channel

The 802.11 WLAN legacy standard cannot provide Quality of Service (QoS) support for multimedia applications because the 802.11 was initially developed for Best Effort services. Hence, the 802.11e a...

Impact of Different Mobility Scenarios on FQM Framework For Supporting Multimedia Applications in Manets

Impact of Different Mobility Scenarios on FQM Framework For Supporting Multimedia Applications in Manets

On the Support of Multimedia Applications over Wireless Mesh Networks

For next generation wireless networks, supporting quality of service (QoS) in multimedia application like video, streaming and voice over IP is a necessary and critical requirement. Wireless Mesh Networking is envisioned as a solution for next networks generation and a promising technology for supporting multimedia application. With decreasing the numbers of mesh clients, QoS will increase automatically. Several research are focused to improve QoS in Wireless Mesh networks (WMNs), they try to improve a basics algorithm, like routing protocols or one of example of canal access, but in moments it no sufficient to ensure a robust solution to transport multimedia application over WMNs. In this paper we propose an efficient routing algorithm for multimedia transmission in the mesh network and an approach of QoS in the MAC layer for facilitated transport video over the network studied.

Supporting multimedia applications through network redesign

SUMMARYRecent evolutions in high‐performance computing and high speed broadband Internet access have paved a way to enterprise‐wide multimedia applications, which require stern QoS from the underlying networks. In this paper, we have explored threefold studies on existing enterprise network, whereby we proposed an analytical approach to evaluate the performance of the existing network; we have examined the feasibility of existing enterprise networks to accommodate voice over Internet protocol (VoIP) services with acceptable QoS, and we have redesigned the enterprise network to accommodate VoIP services to comply with the user defined QoS. The network performance is evaluated by number of VoIP calls sustained by the network, bandwidth utilization, loss rate and latency through Network Simulation (NS‐2) tool. We have derived a cost model to show the cost‐effectiveness of VoIP services over telephonic network. For a medium‐size enterprise network of 200 clients and 9 servers, our simulation results show that the redesign improves the network performance by increasing the number of VoIP calls by 57% and decreasing bandwidth utilization and packet loss rate by 20% and 7%, respectively. Moreover, the proposed network redesign demonstrates that the network can be scalable and it can handle up to 4% increased voice calls in the future maintaining QoS standards. Copyright © 2012 John Wiley & Sons, Ltd.

A Dynamic Physical Rate Adaptation for Multimedia Quality-Based Communications in IEEE_802.11 Wireless Networks

Abstract Assuming that the IEEE802.11 Wireless Local Area Networks (WLANs) are based on a radio/infrared link, they are more sensitive to the channel variations and connection ruptures. Therefore the support for multimedia applications over WLANs becomes non-convenient due to the compliance failure in term of link rate and transmission delay performance. We studied link adaptation facets and the Quality of Service (QoS) requirements essential for successful multimedia transmissions. In fact, the efficiency of rate control diagrams is linked to the fast response for channel variation. The 802.11 physical layers provide multiple transmission rates (different modulation and coding schemes). The last 802.11g-version maintains 12 physical rates up to 54 Mbps at the 2.4 GHz band. As a result, Mobile Stations (MSs) are able to select the appropriate link rate depending on the required QoS and instantaneous channel conditions to enhance the overall system performance. Hence, the implemented link adaptation algorithm symbolizes a vital fraction to achieve highest transmission capability in WLANs. “When to decrease and when to increase the transmission rate?” Are the two fundamental matters that we will be faced when designing a new physical-rate control mechanism? Many research works focus on tuning channel estimation schemes to better detect when the channel condition was improved enough to accommodate a higher rate, and then adapts its transmission rate accordingly. However, those techniques usually entail modifications on the current 802.11 standard. Another way to perform link control is based on local Acknowledgment (Ack) information for the transmitter station. Consequently, two techniques where accepted by the standard due to their efficiency and implementation simplicity. We propose a new dynamic time-based link adaptation mechanism, called MAARF (Modified Adaptive Auto Rate Fallback). Beside the transmission frame results, the new model implements a Round Trip Time (RTT) technique to select adequately an instantaneous link rate. This proposed model is evaluated with most recent techniques adopted by the IEEE 802.11 standard: ARF (Auto Rate Fallback) and AARF (Adaptive ARF) schemes. Simulation results will be given to illustrate the link quality improvement of multimedia transmissions over Wi-Fi networks and to compare its performance with previous published results.

Novel framework for proactive handover with seamless multimedia over WLANs

Supporting multimedia applications over 802.11 wireless LANs requires low latency and seamless handover between multiple access points. However, the existing handover process in 802.11 products suffers from very high delay and frequent service disruption, which are not acceptable for streaming multimedia applications. In order to reduce this high delay and service disruption, the authors have designed and implemented a new proactive handover strategy over 802.11. The strategy intelligently issues proactive scan and handover triggers to reduce the effective channel scanning delay. Subsequently, it reserves resources in advance, to reduce the handoff reconnection delay and provide necessary QoS guarantee. Using actual implementation and simulation study, the authors demonstrate that their proposed strategy is capable of achieving magnitudes of latency, jitter and throughput improvements during the 802.11 handover operations, thereby providing seamless multimedia transmission.

Distributed multicast multichannel paths

Supporting multimedia applications in QoS-aware multicast deployment has become an important research dimension in recent years. Future communication networks will face an increase in traffic driven by multimedia applications with stringent requirements in the following important functions: (1) nodes and links used distributing, (2) packets duplication distributing, (3) QoS supporting, (4) multichannel routing. For improving these four functions, in this paper we propose a new polynomial time algorithm, named Nodes Links Distributed-Multicast Multichannel Routing (NLD-MMR), based on the Constraint-Based Routing (CBR) and Linear Programming (LP). The new algorithm by constructing Distributed Multicast Multichannel Paths (DMMCP) can distribute or compact both paths and traffic. Our simulation study shows that the proposed algorithm, as compared to other available algorithms, performs well and constructs a new generation of optimal paths with the best cost and efficiency.

Using fuzzy link cost and dynamic choice of link quality metrics to achieve QoS and QoE in wireless mesh networks

The growth of multimedia applications and wireless systems requires a new behavior of routing protocols for wireless mesh networks (WMNs). It is necessary to provide not only the minimum requirements for quality of service (QoS), but also to assure the quality of experience (QoE) support for multimedia applications. In this context, the usage of only one link quality metric for routing different types of packets within the network is not enough to ensure applications with suitable QoS and QoE levels. This paper presents a variation of the WMN routing protocol optimized link state routing (OLSR), to achieve QoS and QoE requirements for multimedia applications. It is based on the dynamic choice of metrics and in a fuzzy link cost (FLC) to determine the best routes for multimedia packets. The proposed FLC metric is based on a fuzzy system that uses two link quality metrics, namely expected transmission count (ETX) and minimum delay (MD), to define a new metric. Simulations were performed to demonstrate the performance of the proposed metric compared to the ones present in the original OLSR and other current versions of this protocol. For comparison purposes, it was considered different performance evaluation QoS metrics and the quality of videos received by the user in a higher competition scenario.

Performance modelling and evaluation of telecommunication systems

Due to the tremendous growth in the evolution of telecommunication system and wireless networks, recent developments in telecommunication system and wireless communication technologies and mobile networks has posed various challenges to the researchers in the field of performance modelling. These challenges require effective performance evaluation tools, techniques and methodologies to design new protocols and robust solutions before a global and wide-scale integrated broadband infrastructure of convergent multi-service networks can be established towards the next generation of telecommunication system with efficient support of multimedia applications. As a result, performance modelling and evaluation has gained increasing importance. This special issue solicits papers on advances in the analytical and simulation based modelling and evaluation of new challenges in the telecommunication systems. Papers in this special issue were selected from the IEEE International Workshop on Performance Modelling and Evaluation in Computer and Telecommunication Networks (PMECT2008) in conjunction with the 17th IEEE International Conference on Computer Communications and Networks (ICCCN 2008), held in August 4–7, 2008 at Virgin Islands, USA. These papers were selected by the scientific

A study on video performance of multipoint‐to‐point video streaming with multiple description coding over ad hoc networks

AbstractSupporting multimedia applications over wireless networks has become a very active research topic recently because video applications are forecast to receive high demand in future wireless networks, such as ad hoc networks. However, enabling video transmission over wireless ad hoc networks is more challenging than over other wireless networks due to node mobility, interference, and the absence of a supporting infrastructure. This paper addresses the problem of video transmission over ad hoc networks. We propose to combine Multiple Description Coding (MDC) with multiple source transport (Multipoint‐to‐Point transfer: MP2P) in order to maintain smooth video streaming over wireless ad hoc networks. In this paper, we describe a comprehensive simulation and test bed experiment designed to show the effect of the proposed MP2P video transfer with MDC for two description cases of video streaming over wireless ad hoc networks. The results show that the proposed mechanism successfully improves video transfer performance in terms of video packet reachability and throughput. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(4): 43–50, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20999

A collision-free MAC scheme for multimedia wireless mesh backbone

Wireless mesh networking is a promising wireless technology for future broadband Internet access. In this paper, a novel collision-free medium access control (MAC) scheme supporting multimedia applications is proposed for wireless mesh backbone. The proposed scheme is distributed, simple, and scalable. Benefiting from the fixed locations of wireless routers, the proposed MAC scheme reduces the control overhead greatly as compared with conventional contention-based MAC schemes (e.g., IEEE 802.11). In addition, the proposed scheme can provide guaranteed priority access to real-time traffic and, at the same time, ensure fair channel access to the routers with data traffic. Unlike most of the existing MAC schemes which focus on single-hop transmissions, the proposed MAC scheme takes the intra-flow correlations between up-stream and downstream hops of a multi-hop flow into consideration. To avoid buffer overflow at bottleneck routers, a simple but effective congestion control mechanism is proposed. Simulation results demonstrate that the proposed scheme significantly improves the delay performance of real-time traffic and the end-to-end data throughput, as compared with IEEE 802.11 and distributed packet reservation multiple access (DPRMA). The performance analysis of the proposed scheme is also presented. The accuracy of the analytical results is verified by computer simulations.

Direction-Aware Time Slot Assignment for Largest Bandwidth in Slotted Wireless Ad Hoc Networks

Slotted wireless ad hoc networks are drawing more and more attention because of their advantage of QoS (Quality of Service) support for multimedia applications owing to their collision-free packet transmission. Time slot assignment is an unavoidable and important problem in such networks. The existing time slot assignment methods have in general a drawback of limited available bandwidth due to their local assignment optimization without the consideration of directions of the radio wave transmission of wireless links along the routes in such networks. A new time slot assignment is proposed in this paper in order to overcome this drawback. The proposed assignment is different from the existing methods in the following aspects: a) consideration of link directions during time slot assignment; b) largest bandwidth to be achieved; c) feasibility in resource limited ad hoc networks because of its fast assignment. Moreover, the effectiveness of the proposal is confirmed by some simulation results.

STUDY OF MOBILITY AND QoS OF 802.11 AND 802.11e WIRELESS LAN STANDARDS

Quality of service (QoS) is a key problem in wireless environments where bandwidth is scarce and channel conditions are time varying and sometimes implies highly packet losses. IEEE 802.11b/g/a wireless LAN (WLAN) are the most widely used WLAN standards today, and the IEEE 802.11e QoS enhancement standard exists and introduces QoS support for multimedia applications. This paper presents a class based admission control algorithm for 802.11e based wireless local area networks . The strengths of our admission control is dynamicity and flexibility of the algorithm, which adapts to the situation of the BSS, like global load, number of best effort AC, and position of QSTA by report of QAP. Thus it achieves higher throughput than other admission control for 802.11 e. A summary of many good solutions on admission control for 802.11e is be done, and the model of our admission control is presented. The 802.11e standard starves the low priority traffic in case of high load, and leads to higher collision rates, and did not make a good estimate of weight of queues, so there is an unbalance enters the flows with high priorities. A discussion is presented in detail using simulation-based evaluations, with an aim of comparing results of our admission control algorithm, with the 802.11e standard and the FHCF algorithm. Results reveal an improvement of the network load and a decrease of the number of collisions.

A Study on Video Performance of Multipoint-to-Point Video Streaming with Multiple Description Coding Over Ad Hoc Networks

Supporting multimedia applications over wireless networks has become a very active research topic recently because video applications are forecast to receive high demand in future wireless networks, such as ad hoc networks. However, enabling video transmission over wireless ad hoc networks is more challenging than over other wireless networks due to node mobility, interference, and the absence of a supporting infrastructure. This paper addresses the problem of video transmission over ad hoc networks. We propose to combine Multiple Description Coding (MDC) with multiple source transport (Multipoint-to-Point transfer: MP2P) in order to maintain smooth video streaming over wireless ad hoc networks. In this paper, we describe a comprehensive simulation and test bed experiment designed to show the effect of the proposed MP2P video transfer with MDC for two description cases of video streaming over wireless ad hoc networks. The results show that the proposed mechanism successfully improves video transfer performance in terms of video packet reachability and throughput. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 170(4): 43–50, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20999

A Perspective of Layerless Communications

Recent advances in wireless and mobile communications provide ample opportunities for introducing new services. Supporting multimedia applications and services over wireless networks is challenging due to constraints and heterogeneities such as limited battery power, limited bandwidth, random time-varying fading effect, different protocols and standards, stringent quality of service (QoS) requirements. Cross-layer design methodologies are one way of addressing these challenges and providing reliable and high-quality end-to-end performance in wireless multimedia communications. This paper looks beyond cross-layer design from the perspective of simplifying the cross-layer procedures towards layers merging. Studies and observations are based on the use of cognitive radio technology as the means for optimization of the cross-layer design process.

Multi-user video streaming over multi-hop wireless networks: A distributed, cross-layer approach based on priority queuing

Emerging multi-hop wireless networks provide a low-cost and flexible infrastructure that can be simultaneously utilized by multiple users for a variety of applications, including delay-sensitive multimedia transmission. However, this wireless infrastructure is often unreliable and provides dynamically varying resources with only limited quality of service (QoS) support for multimedia applications. To cope with the time-varying QoS, existing algorithms often rely on non-scalable, flow-based optimizations to allocate the available network resources (paths and transmission opportunities) across the various multimedia users. Moreover, previous research seldom optimizes jointly the dynamic routing with the adaptation and protection techniques available at the medium access control (MAC) or physical (PHY) layers. In this paper, we propose a distributed packet-based cross-layer algorithm to maximize the decoded video quality of multiple users engaged in simultaneous real-time streaming sessions over the same multi-hop wireless network. Our algorithm explicitly considers packet-based distortion impact and delay constraints in assigning priorities to the various packets and then relies on priority queuing to drive the optimization of the various users' transmission strategies across the protocol layers as well as across the multi-hop network. The proposed solution is enabled by the scalable coding of the video content (i.e. users can transmit and consume video at different quality levels) and the cross-layer optimization strategies, which allow priority-based adaptation to varying channel conditions and available resources. The cross-layer strategies - application layer packet scheduling, the policy for choosing the relays, the MAC retransmission strategies, the PHY modulation and coding schemes - are optimized per packet, at each node, in a distributed manner. The main component of the proposed solution is a low-complexity, distributed, and dynamic routing algorithm, which relies on prioritized queuing to select the path and time reservation for the various packets, while explicitly considering instantaneous channel conditions, queuing delays and the resulting interference. Our results demonstrate the merits and need for end-to-end cross-layer optimization in order to provide an efficient solution for real-time video transmission using existing protocols and infrastructures. Importantly, our proposed delay-driven, packet-based transmission is superior in terms of both network scalability and video quality performance to previous flow-based solutions that statically allocate resources based on predetermined paths and rate requirements. In addition, the results provide important insights that can guide the design of network infrastructures and streaming protocols for video streaming.

End-to-end QoS framework for heterogeneous wired-cum-wireless networks

With information access becoming more and more ubiquitous, there is a need for providing QoS support for communication that spans wired and wireless networks. For the wired side, RSVP/SBM has been widely accepted as a flow reservation scheme in IEEE 802 style LANs. Thus, it would be desirable to investigate the integration of RSVP and a flow reservation scheme in wireless LANs, as an end-to-end solution for QoS guarantee in wired-cum-wireless networks. For this purpose, we propose WRESV, a lightweight RSVP-like flow reservation and admission control scheme for IEEE 802.11 wireless LANs. Using WRESV, wired/wireless integration can be easily implemented by cross-layer interaction at the Access Point. Main components of the integration are RSVP-WRESV parameter mapping and the initiation of new reservation messages, depending on where senders/receivers are located. In addition, to support smooth roaming of mobile users among different basic service sets (BSS), we devise an efficient handoff scheme that considers both the flow rate demand and network resource availability for continuous QoS support. Furthermore, various optimizations for supporting multicast session and QoS re-negotiation are proposed for better performance improvement. Extensive simulation results showthat the proposed scheme is promising in enriching the QoS support of multimedia applications in heterogeneous wired-cum-wireless networks

Seamless SIP-based mobility for multimedia applications

Application-level protocol abstraction is required to support seamless mobility in next-generation heterogeneous wireless networks. Session initiation protocol (SIP) provides the required abstraction for mobility support for multimedia applications in such networks. However, the handoff procedure with SIP suffers from undesirable delay and hence packet loss in some cases, which is detrimental to applications like voice over IP (VoIP) or streaming video that demand stringent quality of service (QoS) requirements. In this article we present a SIP-based architecture that supports soft handoff for IP-centric wireless networks. Soft handoff ensures that there is no packet loss and that the end-to-end delay jitter is kept under control.