Video streaming over mobile wireless ad hoc networks

Motivation

At the end of the 1990s, the IEEE 802.11 subcommittee adopted the term “ad hoc model” to denote a new communication paradigm in which nearby nodes can communicate directly by exploiting wireless networks technologies as Zigbee (IEEE 802.15.4), Bluetooth (IEEE 802.15.1), 802.11 (Wi-Fi) or 802.16 (WiMAX). The first commercial applications of the ad hoc technology allow network devices to establishment a single-hop ad hoc network, which are the simplest form of infrastructureless networks or self-organizing networks, by interconnecting devices that are within the same transmission range. However, soon emerged the multihop network paradigm, often referred to as Mobile Ad hoc Networks (MANETs), which was conceived to extend the possibility to information exchange with any wireless node, without the need to develop any network infrastructure. In MANETs, nearby users directly communicate (setting their wireless network interfaces of their devices in ad hoc mode) not only to exchange their data but also to relay the traffic of other network nodes that cannot directly communicate. For this reason, in a MANET, wireless devices must cooperatively provide the functionality that is usually provided by the network infrastructure (e.g., routers, switches, servers). Figure 1 provides a conceptual representation of a MANET. In many situations such as catastrophes or emergencies in which there are no infrastructures or they cannot be installed because of geographical or temporal reasons, this kind of network may be an ideal solution.

Figure 1. Conceptual representation of a mobile ad hoc network

In addition, a mobile ad hoc network not only works in isolated mode but also it can be connected to a larger network scenario like the one shown in the Figure 2. With the advent of newer network architectures, new scenarios are emerging as applications of MANETs such as Smart cities and IoT (Internet of Things). In this sense, mobile ad hoc networks are becoming an integral part of next-generation networks (4G) because of its flexibility, autoconfiguration capability, lack of infrastructure, ease of maintenance, self-administration capabilities and cost-effectiveness.

Figure 2. MANET extending Internet services to a non-infrastructure area

In this context, the mobile ad hoc networks have been an intense research theme in the academic community during the last two decades. Taking as reference the MANET protocol stack of the MANET IETF working group (see Figure 3), all layers have been subject of research activities. Some enhancements at the physical layer included the use of directional antennas, improved signal processing schemes, software defined radio, and mesh technologies; while at the MAC layer there have been several proposals for collision control and efficient energy consumption. However, most research works have been mainly focused on the network layer [2]–[7] while higher layers are the areas in MANETs theme where less have been performed research activities [1].

One of the most important force that have driven the research activities in MANETs are the multimedia applications. At recent years, video streaming over MANETs is a very fascinating research topic, mainly due to the high popularity of mobile devices, such as notebooks, smartphones, and tablets. Additionally, the computing capabilities of these devices are growing quickly and, at the same time, the demand of multimedia content from mobile devices is becoming increasingly widespread.

Figure 3. MANET layered stack proposed by IETF MANET working group [1]

Supporting video streaming services in mobile ad hoc networks presents many challenges due to the difficulty of providing certain quality in the shared wireless medium and the dynamic topology of MANETs [8]. These issues impose the necessity of developing new routing protocols with the aim of achieving efficient routes between the nodes where information is available in destination nodes reliably and within boundary time. Therefore, routing protocols should have a good performance in terms of overhead, a route convergence and bandwidth consumption, even when there are changes in traffic load or the number of nodes. Besides routing protocols, video delivery can be improved through cross-layer techniques since some functions cannot be assigned to a single layer (e.g. energy control and cooperation). Practical cross-layer solutions may try to improve communications gathering information from several layers about routing or network state in order to allow multimedia applications to adapt bitrates or even request recent lost packets [9]. This kind of technique could be very versatile to handle situations with network congestion or important video degradation caused by node mobility. Therefore, despite the complexity of providing hard Quality of Service (QoS) for multimedia applications over MANETs, there are still many options to improve video streaming quality, through holistic approaches that involve routing, transport and application layers.

In this sense, video streaming over ad hoc networks has been widely studied in our research group, leading to the creation of three main lines (click in each one for more information):

References

[1] S. Basagni, M. Conti, S. Giordano et al., “Mobile Ad Hoc Networking: The Cutting Edge Directions,” Wiley,  2nd Edition, 2013.
[2] M. K. Gulati and K. Kumar, “QoS routing protocols for mobile ad hoc networks: a survey,” Int. J. Wirel. Mob. Comput., vol. 5, no. 2, pp. 107–118, Jan. 2012.
[3] S. Zheng, L. Li, and Y. Li, “A QoS Routing Protocol for Mobile Ad Hoc Networks Based on Multipath,” J. Netw., vol. 7, no. 4, 2012.
[4] L. Ullah Khan, S. A. Mahmud, M. H. Zafar, G. M. Khan, and H. S. Al-Raweshidy, “M-AODV: Modified Ad Hoc On-demand distance vector routing scheme,” in 9th International Symposium on Communication Systems, Networks Digital Signal Processing (CSNDSP), 2014, pp. 18–22.
[5] J. Zhou, L. Liu, Y. Deng, and S. Huang, “A QoS Routing Protocol with Bandwidth Allocation in Multichannel Ad Hoc Networks,” Wirel. Pers. Commun., vol. 75, no. 1, pp. 273–291, Mar. 2014.
[6] M. Sanabani, R. Alsaqour, and S. Kurkushi, “A reverse and enhanced aodv routing protocol for manets,” ARPN J. Eng. Appl. Sci., vol. 9, no. 2, pp. 153–159, 2014.
[7] T. Coelho, A. Costa, J. Macedo, and M. J. Nicolau, “Improving Stability in QoS Routing for Ad-Hoc Networks,” Ad Hoc Networks, Eds. Springer International Publishing, 2014, pp. 121–133.
[8] Y. Xu, J. D. Deng, M. Nowostawski, and M. K. Purvis, “Optimized routing for video streaming in multi-hop wireless networks using analytical capacity estimation,” J. Comput. Syst. Sci., vol. 81, no. 1, pp. 145–157, Feb. 2015.
[9] S. Pudlewski, N. Cen, Z. Guan, and T. Melodia, “Video Transmission Over Lossy Wireless Networks: A Cross-Layer Perspective,” IEEE J. Sel. Top. Signal Process., vol. 9, no. 1, pp. 6–21, Feb. 2015.