Adaptive and ubiquitous video streaming over Wireless Mesh Networks

Scalable video applications have been gaining popularity during last years. Providing high quality video over wireless networks towards heterogeneous receivers is a challenging task due to erratic and time-varying nature of a wireless channel. Compressed video bit-streams, such as Scalable Video Coding (SVC), are very vulnerable to channel disturbances when transmitted over error-prone wireless channels. Transmission errors not only corrupt the current frame, but also propagate to next frames along motions prediction path. In this paper we propose a novel scheme for transmission of SVC-based streams over Wireless Mesh Network (WMN) with Unequal Error Protection (UEP) based on Appropriate Path Selection (APS) and Network Coding (NC). The scheme tries to select appropriate paths based on Grey Relational Analysis (GRA) for different SVC layers. It chooses the best path for most important layer, base layer, and less stable paths for enhancement layers. Some nearby nodes along the transmission path are selected for recoding their received packets and store them in buffers for some period of time. The nearby nodes coded packets can be transmit to receivers for recovering the lost packets.

Video communication requires sufficient resources to obtain the desired image quality. Availability of bandwidth and screen resolution from different devices on the client end, as well as compression techniques used for transmission also significantly influence to the video quality. Even though the H.264/AVC video compression standard and its scalable extension is known as Scalable Video Coding (SVC) was introduced and successfully addressed the challenge, some weaknesses persist especially for high-resolution video transmissions. The size of the bitstream generated by the SVC standard for ultra-high resolution video compression can only be met if transmitted on a network with a large bandwidth. The Scalable High-Efficiency Video Coding (SHVC) were introduced to overcome problems in the SVC standards. The new video compression standard is proven to reduce bandwidth requirements by up to 46.41 % compared to the SVC standards for the same video quality. This study introduces the performance analysis of SHVC standard video transmission as compared to SVC standard. Both compression standards are transmitted and emulated through network emulator called Mininet-Wifi to get the real transmission picture. The client-server video transmission scheme with different bandwidth and various client position are set in the experiment scenario. It is found that transmission time, packet loss, and video reconstruction quality on scalable video transmission with SHVC standard is better than scalable video transmissions with SVC standard.

Replication strategy has been considered as a promising technique for improving data accessibility as well as reducing gateway overload in wireless mesh networks (WMNs). In this regard, popular data is stored in some indicated mesh routers within the network being closer to the users. However, in video streaming applications over WMNs, due to the large size of the videos, it is very challenging for replication strategies to achieve a high quality of experience (QoE) while consuming a minimum storage capacity requirement (SCR). In this paper, as a solution, we propose a novel replication strategy to overcome such challenge by determining an optimal replication density for each segment of a video streaming. The optimal result is based on exploiting not only the skewed access probabilities of video segments as conventional replication strategies but also the skewed encoding rate-distortion information and the loss probability of each frame of a segment. We carefully study the optimization problem in two forms. In the original problem form, our method consumes a minimum SCR under a given constraint of quality playback. In the duality problem form, the proposed scheme provides highest quality playback for a given SCR constraint. Simulation results show that our proposed approach gains a better performance in terms of QoE improvement and SCR saving compared to other existing replication strategies.

The impact of interference-aware routing metrics on video streaming in Wireless Mesh Networks

Chapter 11 - Wireless Network Security

Resource allocation and admission control algorithm based on non-cooperation game in wireless mesh networks

Wireless Mesh Networks (WMNs) integrate the advantages of WLANs and mobile Ad Hoc networks, which have become the key techniques of next-generation wireless networks in the context of emergency recovery. Wireless Mesh Networks (WMNs) are multi-hop wireless networks with instant deployment, self-healing, self-organization and self-configuration features. These capabilities make WMNs a promising technology for incident and emergency communication. An incident area network (IAN) needs a reliable and lively routing path during disaster recovery and emergency response operations when infrastructure-based communications and power resources have been destroyed and no routes are available. Power aware routing plays a significant role in WMNs, in order to provide continuous efficient emergency services. The existing power aware routing algorithms used in wireless networks cannot fully fit the characteristics of WMNs, to be used for emergency recovery. This paper proposes a power aware routing algorithm (PARA) for WMNs, which selects optimal paths to send packets, mainly based on the power level of next node along the path. This algorithm was implemented and tested in a proven simulator. The analytic results show that the proposed power node-type aware routing algorithm metric can clearly improve the network performance by reducing the network overheads and maintaining a high delivery ratio with low latency.

Nowadays there are inexpensive WiFi devices that have fostered the deployment of wireless communities. Well known routing protocols used in the Internet do not fit well to time varying characteristic of wireless networks. This has motivated an intensive research on routing protocols for wireless mesh networks. At this time there are a number of mature and stable implementations that are being deployed in production networks. In this paper we focus on the experimental evaluation of a production Wireless Mesh network being deployed in a testbed at Universitat Politecnica de Catalunya (UPC) and a quarter of the city of Barcelona, Spain. To our best knowledge, this is the first paper where a production community wireless network using 802.11an is analyzed.

The wireless mesh networks (WMNs) have become one of the popular technologies of the wireless network utilization. WMN provides reliable and scalable wireless network because of its features such as dynamic self-organizing, self-configuring, Self-managing and self-healing. Routing protocols play an essential role in finding and establishing an active route from a source to a destination in WMNs. This article focuses on the performance evaluation and comparison of some routing protocols commonly used in WMNs for VoIP application: AODV, DSR, OLSR and TORA has been investigated over client Wireless Mesh Networks based on OPNET simulation in a different network sizes and mobility. This article presents a background of some designs and solutions based on an elaborated simulation investigation. The performance comparisons are carried out with regard to the node variation in network sizing and mobility. Based on the empirical outputs, the authors suggested that to utilize a specific routing protocol in certain situations.

There is a growing interest in ad hoc wireless networking internationally, due to the great cost in infrastructure and the time delay for deployment for new traditional wireless networks for a specific purpose (i.e. cellular systems). The interest arises from the possibility of delivering telecommunication services rapidly and with the reduced needs for costly generic infrastructure. Examples of such services include, among others, a convention where a large number of people are concentrated in a limited geographical area, a university campus with a great density of telecommunication users, or even a disaster area where the fixed infrastructure have been damaged. In most examples, ad hoc wireless networks may complement or replace the existing wireless telecommunications infrastructure. One flavor of ad hoc wireless networks that is of interest in this context, and is well adapted to the Lebanese market, are wireless mesh networks (WMN). We propose that the proliferation of WiFi hotspots in high-density areas of population in Lebanon forms the basis of deployment of mesh routers for a WMN. Of specific interest is to be able to use the dense infrastructure of GSM-EDGE (and in the future HSUPA) cellular networks in Lebanon to interconnect those routers in specific locations where it will be hard to deploy additional fixed and cumbersome cellular infrastructure. Locations where hotspots are already deployed (commercial centers, university campuses, business areas, etc.) or could be deployed for special events (conventions, concerts, etc.) could thus be interconnected in a hybrid wireless network, resulting in significantly increased capacity of the network for local voice and data traffic at little additional infrastructure cost. Furthermore, this could a preliminary step for direct connection between the mesh routers and not via the cellular network, into what will become a full- fledged WMN. The structure of the paper is as follows: section the author gives an introduction on ad hoc wireless networks; section II describes WMN and define the design issues of WMN; in section III, we look at a proposed scenario for deployment of WMNs in the Lebanese market and the issues of interconnection with the GSM networks. We will conclude in section IV.

Intrusion Detection Systems(IDSs) are widely used to detect both known attacks and unknown attacks performed by internal and external attackers in wireless networks. However, challenging issues for developing IDSs in Wireless Mesh Networks (WMNs) are 1) supporting interoperability and 2) handling volatile parameters. In addition, security standards for WMN are still in draft stage, and to protect the WMN, IDSs of similar wireless networks such as wireless sensor, Ad-Hoc, MANET can be adopted, but the best performance is not guaranteed. In this paper, we have classified the existing IDSs for wireless networks into four categories namely single layer IDS, cross-layer IDS, reputation-based IDS, reputation based cross-layer IDS, and analyzed the performance of these IDSs with core-layer attacks and detection methodology. Based on our analysis, we address the loopholes in existing IDSs and specify research directions for strengthening the existing IDSs and for developing new efficient IDSs with respect to backbone mesh and client mesh networks.

Wireless mesh network is a network implemented over a wireless local area network (LAN), and its infrastructure type is decentralized, relatively inexpensive, reliable, and resilient since the wireless routers are often static and not powered by batteries. In addition, the access points (routers) seldom change their positions in wireless mesh networks, and some wireless nodes have gateway functions to provide the connectivity to the Internet. Therefore, such networks behave almost like wired networks with infrequent topology changes and limited node failures. Due to these good properties and potential applications such as providing commercial Internet access to residents and local businesses, wireless mesh networks have drawn a lot of attention in recent years. For example, wireless mesh networks are being used as the last mile for extending the Internet connectivity for mobile nodes. In addition, some commercial deployments of multihop wireless meshes are already in the works. For instance, a number of mesh networks have been deployed in some cities of the United States, including Medford, Oregon, and cities in Minnesota [4]. Unlike traditional wired network, close-by mesh routers share certain wireless channels and the capacity of wireless mesh network will be increased tremendously when extending from a single channel model to a multiradio, multichannel, multihop model. For example, if two nodes vi and v j could communicate with each other by channel f1, and both nodes have at least one more available network interface cards, which could operate on another channel f2, if f2 is also available for both nodes, vi and v j could use both f1 and f2 to communicate simultaneously. When such cases are applied to more wireless nodes, the throughput of a wireless network will be increased tremendously.

The wireless mesh network is a new emerging technology that will change the world of industrial networks connectivity to more efficient and profitable. Mesh networks consist of static wireless nodes and mobile customer; have emerged as a key technology fornew generation networks. The Quality of Service (QOS) is designed to promote and support multimedia applications (audio and video), real time. However guarantee of QoS on wireless networks is a difficult problem by comparison at its deployment in a wired IP network. In this paper, we present an efficient routing protocol named as “QoS- Cluster Based Routing Protocol” (Q-CBRP) to support QoS in Wireless Mesh Network.

3G video broadcast services employ forward error correction, together with Reed-Solomon erasure coding with appropriate interleaving, in the MAC layer to deal with bursts of errors. However, this method of error recovery is less effective at the margins of coverage where channel conditions are bad, so that mobiles experience higher error rates and longer error bursts: this effectively limits the service area for video applications. To overcome this problem, we augment scalable video coding (SVC) with a selective repetition scheme, which retransmits those packets within the layered structure of SVC that are most important for video. Simulations using an the example MPEG-4 fine granularity scalability video demonstrate that our scheme safeguards the important packets and improves the service quality. Furthermore, energy measurements show that it also extends battery life.

Wireless Mesh Networks (WMNs) cannot completely guarantee good performance of traffic sources such as video streaming. To improve the network performance, this study proposes an efficient engineering solution named Wireless-to-Ethernet-Mesh-Portal-Passageway (WEMPP) that allows effective use of wired communication in WMNs. WEMPP permits transmitting data through wired and stable paths even when the destination is in the same network as the source (Intra-traffic). Tested with four popular routing protocols (Optimized Link State Routing or OLSR as a proactive protocol, Dynamic MANET On-demand or DYMO as a reactive protocol, DYMO with spanning tree ability and HWMP), WEMPP considerably decreases the end-to-end delay, jitter, contentions and interferences on nodes, even when the network size or density varies. WEMPP is also cost-effective and increases the network throughput. Moreover, in contrast to solutions proposed by previous studies, WEMPP is easily implemented by modifying the firmware of the actual Ethernet hardware without altering the routing protocols and/or the functionality of the IP/MAC/Upper layers. In fact, there is no need for modifying the functionalities of other mesh components in order to work with WEMPPs. The results of this study show that WEMPP significantly increases the performance of all routing protocols, thus leading to better video quality on nodes.