DESIGN AND DEVELOPMENT OF RELIABLE ROUTING PROTOCOLS FOR VIDEO TRANSMISSION IN WIRELESS MESH NETWORKS
Wireless network deployment is more affordable compared to a wired network installation and the supported speeds are up to 1.3 Gbps in the widely used 802.11ac, making the wireless networking as the most preferable solution for Internet connectivity. Although the wired access is more stable and of high-bandwidth, it is unsuitable in environments where mobile devices opportunistically arrive or leave. The proliferation of these devices, such as laptops, tablets and smartphones, has been instrumental in bringing even more the development of the wireless access to the attention of networking researchers.
More specifically, the routing problem remains one of the most challenging issues in the wireless access networking, while routing seems to be an attractive solution to this problem.
In general the available routing schemes does not choose the best sequence of relays between the source and the destination, as it happens in the most common routing algorithms, but it exploits broadcast transmissions and creates cooperative diversity sending packets through multiple relays simultaneously.
Especially in the case of multicast scenarios, opportunistic routing outperforms traditional routing by exploiting Network Coding (NC) and improving the routing efficiency. Examples of these scenarios are large scale events happening in public areas, such as audio concerts or football matches, where the majority of the requests address the same multicast and real-time video stream e.g. a different view of the stadium. Although the wireless access is able to support these scenarios, the successful coverage of a public area with use of multiple WiFi gateways is impractical and inefficient. The collaborative retransmission and processing of overheard information at some mobile devices, which act as wireless relays, offers coverage extension and throughput gain for all devices.
Studies on WMN multimedia communications have investigated the use of modern wireless techniques to improve transmission performance inside a WMN. Zeng et al.  used multiple channels with no overlap or low overlap to increase WMN multicast capacity. Moreover, Breadth First Search was employed to control the number of relay nodes in order to reduce interference that could decrease WMN capacity.
However, due to the limited available channels, the proposed multicast scheme may not achieve sufficient capacity to carry multi-source multicast over multiple WMN hops. Hence, Tu  explored how to efficiently utilize channel capacity. By designing a new channel aggregation scheme and a new flow scheduling scheme in multi-flow multicasting scenarios, extra multicasting opportunities are achieved when WMN channels are considered to be saturated in conventional studies. Apart from multiple channels, the advantages of multiple transmission rates have also been studied in the literature.
Qadir et al.  proposed a WMN broadcast scheme which enables a mesh node to schedule multiple channels to work at different rates in order to provide short delays to broadcast receivers. With this scheme, a channel transmits at a rate that enables data to reach neighbours located outside the coverage of any transmission rates larger than the employed rate.
In , Xiong et al. proposed PeerCast to engage mesh users in cooperative relaying, allowing access points to adaptively adjust transmission rates to avoid bottleneck nodes.
Hou et al.  explored cognitive radio technology to make use of spare licensed radio spectrum to gain extra transmission capacity for wireless multimedia communications. A framework that employs cooperative transmissions and network or superposition coding to multicast layered videos in multi-channel cognitive radio networks is proposed.
Bhattacharya et al.  split a multicast stream to fit it into licensed spectrum fragments with different sizes.
Lakshmanan et al.  presented a multi-gateway association model in which a mesh user may adaptively choose different mesh gateways to transmit different packets to a single destination. Although the model helps to balance traffic load in a WMN, it unfortunately generates complicated topologies if being used to send multimedia packets to a group of receivers.
Liu et al.  investigated the integration of a WMN with the Internet via mesh gateways. This work focuses on unicast traffic, and shows that the scalability of network capacity would be significantly increased if Internet shortcuts were employed.
Ruiz et al.  proposed a routing mechanism where mesh nodes form an island with prefix continuity.Mesh nodes connect to the Internet through a shared closest gateway. The selection of closest gateways purely depends on topology, failing to consider the tradeoff between the selection of a closer but more congested gateway vs. the use of a farther, less utilized gateway.
Phase 1: Energy and Bandwidth Aware Opportunistic Routing Mechanism
Multipath routing mechanism will be used. In this phase of research work, once multiple paths between source nodes and destination nodes are obtained, each route will calculate energy and bandwidth of the available routes. Based on that, we aim to propose a routing mechanism which is energy aware as well as bandwidth aware. Opportunistic routing is also employed in order to maintain the quality of the wireless links sustainable.
Phase 2: Delay Aware Geographic Routing Mechanism
Initially, the deployed nodes over the terrain are obtained with their location information. After that multiple paths between several source nodes and destination nodes are taken into account. The delay is calculated for each route. Based on that, in this phase of research, we aim to propose a delay aware geographic routing. Video encoding schemes will be analyzed and the best video coding scheme will be employed in this part of research.
Phase 3: Swarm Intelligence based Hybrid Routing Mechanism
In this phase of research, performance analysis of various swarm intelligence techniques is performed with multipath routing. Then suitable swarm intelligence technique will be chosen. In this hybrid routing mechanism, the positive factors of proactive routing as well as reactive routing will be obtained. Also certain metrics also employed in order to ensure quality of experience.
Simulation Settings and Performance Metrics
Simulator NS 3.25
Terrain Size 500 m X 500m
Channel Width 20 MHz
Spatial streams 1
Transmission power 15 dBmNumber of Mobile Nodes 15, 20, 25, 30, 35
The following metrics are taken into account for evaluating the performance of the proposed works.
Mean Opinion Score
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