https://www.cs.montana.edu/courses/csci566/Ref/WMSN-Survey.pdf

A survey on wireless multimedia sensor networks

Unmanned aerial vehicles (UAVs) have enormous potential in the public and civil domains. These are particularly useful in applications, where human lives would otherwise be endangered. Multi-UAV systems can collaboratively complete missions more efficiently and economically as compared to single UAV systems. However, there are many issues to be resolved before effective use of UAVs can be made to provide stable and reliable context-specific networks. Much of the work carried out in the areas of mobile ad hoc networks (MANETs), and vehicular ad hoc networks (VANETs) does not address the unique characteristics of the UAV networks. UAV networks may vary from slow dynamic to dynamic and have intermittent links and fluid topology. While it is believed that ad hoc mesh network would be most suitable for UAV networks yet the architecture of multi-UAV networks has been an understudied area. Software defined networking (SDN) could facilitate flexible deployment and management of new services and help reduce cost, increase security and availability in networks. Routing demands of UAV networks go beyond the needs of MANETS and VANETS. Protocols are required that would adapt to high mobility, dynamic topology, intermittent links, power constraints, and changing link quality. UAVs may fail and the network may get partitioned making delay and disruption tolerance an important design consideration. Limited life of the node and dynamicity of the network lead to the requirement of seamless handovers, where researchers are looking at the work done in the areas of MANETs and VANETs, but the jury is still out. As energy supply on UAVs is limited, protocols in various layers should contribute toward greening of the network. This paper surveys the work done toward all of these outstanding issues, relating to this new class of networks, so as to spur further research in these areas.

Survey of Important Issues in UAV Communication Networks

Over the last decade, the paradigm of Wireless Mesh Networks (WMNs) has matured to a reasonably commonly understood one, and there has been extensive research on various areas related to WMNs such as design, deployment, protocols, performance, etc. The quantity of research being conducted in the area of wireless mesh design has dramatically increased in the past few years, due to increasing interest in this paradigm as its potential for the "last few miles", and the possibility of significant wireless services in metropolitan area networks. This recent work has focused increasingly on joint design problems, together with studies in designing specific aspects of the WMN such as routing, power control etc. in isolation. While excellent surveys and tutorials pertaining to WMNs exist in literature, the explosive growth of research in the area of specific design issues, and especially joint design, has left them behind. Our objective in this paper is to identify the fundamental WMN design problems of interference modeling, power control, topology control, link scheduling, and routing, and provide brief overviews, together with a survey of the recent research on these topics, with special stress on joint design methods. We believe this paper will fulfill an outstanding need in informing the interested student and researcher in getting familiar with this abundant recent research area, and starting research.

A Survey of Network Design Problems and Joint Design Approaches in Wireless Mesh Networks

In this paper, we consider the connected target coverage (CTC) problem with the objective of maximizing the network lifetime by scheduling sensors into multiple sets, each of which can maintain both target coverage and connectivity among all the active sensors and the sink. We model the CTC problem as a maximum cover tree (MCT) problem and prove that the MCT problem is NP-Complete. We determine an upper bound on the network lifetime for the MCT problem and then develop a (1+w)H(M circ) approximation algorithm to solve it, where w is an arbitrarily small number, H(M circ)=1 lesilesM circ(1/i) and M circ is the maximum number of targets in the sensing area of any sensor. As the protocol cost of the approximation algorithm may be high in practice, we develop a faster heuristic algorithm based on the approximation algorithm called Communication Weighted Greedy Cover (CWGC) algorithm and present a distributed implementation of the heuristic algorithm. We study the performance of the approximation algorithm and CWGC algorithm by comparing them with the lifetime upper bound and other basic algorithms that consider the coverage and connectivity problems independently. Simulation results show that the approximation algorithm and CWGC algorithm perform much better than others in terms of the network lifetime and the performance improvement can be up to 45% than the best-known basic algorithm. The lifetime obtained by our algorithms is close to the upper bound. Compared with the approximation algorithm, the CWGC algorithm can achieve a similar performance in terms of the network lifetime with a lower protocol cost.

Lifetime maximization for connected target coverage in wireless sensor networks

For successful data delivery, the destination nodes should be listening to the medium to receive data when the sender node starts data communication. To achieve this synchronization, there are different rendezvous schemes, among which the most energy-efficient is utilizing wakeup receivers. Current hardware technologies of wake-up receivers enable us to evaluate them as a promising solution for wireless sensor networks. In this article the benefits achieved with wake-up receivers are investigated along with the challenges observed. In addition, an overview of state-of-the-art hardware and networking protocol proposals is presented. As wake-up receivers offer new opportunities, new potential application areas are also presented and discussed.

Wake-up receivers for wireless sensor networks: benefits and challenges

Within the short span of a decade, Wi-Fi hotspots have revolutionized Internet service provisioning. With the increasing popularity and rising demand for more public Wi-Fi hotspots, network service providers are facing a daunting task. Wi-Fi hotspots typically require extensive wired infrastructure to access the backhaul network, which is often expensive and time consuming to provide in such situations. wireless mesh networks (WMNs) offer an easy and economical alternative for providing broadband wireless Internet connectivity and could be called the web-in-the-sky. In place of an underlying wired backbone, a WMN forms a wireless backhaul network, thus obviating the need for extensive cabling. They are based on multihop communication paradigms that dynamically form a connected network. However, multihop wireless communication is severely plagued by many limitations such as low throughput and limited capacity. In this article we point out key challenges that are impeding the rapid progress of this upcoming technology. We systematically examine each layer of the network and discuss the feasibility of some state-of-the-art technologies/protocols for adequately addressing these challenges. We also provide broader and deeper insight to many other issues that are of paramount importance for the successful deployment and wider acceptance of WMNs.

Wireless Mesh Networks: Current Challenges and Future Directions of Web-In-The-Sky

Wireless mesh networks are envisioned to support the wired backbone with a wireless backbone for providing Internet connectivity to residential areas and offices. Routing protocols designed for mobile ad hoc networks (MANETs) primarily concentrate on finding a single best possible route to any destination out of the various paths available. However in wireless mesh networks, traffic is primarily routed either towards the Internet gateways (IGWs) or from the IGWs to the access points (APs). Thus, if multiple APs choose the best throughput path towards a gateway, the traffic loads on certain paths and mesh routers increases tremendously thereby deteriorating the overall performance of the network. To this end, we propose a novel multi-path hybrid routing protocol, multipath mesh (MMESH), that effectively discovers multiple paths. We also propose elegant traffic splitting algorithms for balancing traffic over these multiple paths to synergistically improve the overall performance. Through extensive simulations, we observe that our protocol works very well to cope with the variations in the network. Our protocol also improves the performance of flows traversing multiple hops

Multipath Routing in Wireless Mesh Networks

Wireless Mesh Networks (WMNs) are evolving to be the key technology of the future As the WMNs are envisioned to provide high bandwidth broadband service to a large community of users, the Internet Gateway (IGW) which acts as a central point of internet attachment for the mesh routers, it is likely to be a potential bottleneck because of its limited wireless link capacity We propose a novel technique that elegantly balances the load among the different IGWs in a WMN We switch the point of attachment of an active source serviced gateway depending on the average queue length at the IGW The proposed load balancing scheme includes: an initial gateway discovery module, which determines a primary gateway for a mesh router and a load balancing module that rebalances the load among the gateways We use ns-2 [9] for evaluating our proposed scheme and we observe that the proposed scheme is able to balance the traffic efficiently

Achieving Load Balancing in Wireless Mesh Networks Through Multiple Gateways

In IEEE 802.11 based mobile ad hoc networks (MANET) multicast packets are generally forwarded as one hop broadcast; mainly to reach all the multicast members in the neighborhood in a single transmission. Because of the broadcast property of the forwarding, packets suffer from increased instances of the hidden terminal problem. Mobility of nodes makes things more difficult, and unlike unicast transmissions where MAC can detect the movement of a nexthop by making several retries, it is not possible in case of multicast forwarding. To address these issues, we propose a multicast aware MAC protocol (MMP) for MANET. The basic objective of MMP is to provide a MAC layer support for multicast traffic. This is done by attaching an extended multicast header (EMH) by the multicast agent, which provides the address of the nexthop nodes that are supposed to receive the multicast packet. The MAC layer in MMP uses the EMH field to support an ACK based data delivery. After sending the data packet, the transmitter waits for the ACK from each of its destinations in a strictly sequential order. A retransmission of the multicast packet is performed only if the ACK from any of the nodes in EMH is missing. We compare MMP with IEEE 802.11 and results show that MMP substantially improves the performance of multicast packet delivery in MANET without creating much MAC overhead. In addition, MMP provides a better mechanism to detect the movement of its nexthop members.

Supporting MAC layer multicast in IEEE 802.11 based MANETs: issues and solutions

Wireless mesh networks exploit multi-hop wireless communications between access points to replace wired infrastructure. However, in multi-hop networks, effective bandwidth decreases with increasing number of hops, mainly due to increased spatial contention. Longer hop length flows suffer from extremely low throughputs which is highly undesirable in the envisioned scenarios for mesh networks. In this paper, we show that queue/buffer management, at intermediate relay mesh nodes, plays an important role in limiting the performance of longer hop length flows. We propose a novel queue management algorithm for IEEE 802.11s based mesh networks that improves the performance of multihop flows by fairly sharing the available buffer at each mesh point among all the active source nodes whose flows are being forwarded. Extensive simulations reveal that our proposed scheme substantially improves the performance of multihop flows. We also identify some important design issues that should be considered for the practical deployment of such mesh networks.

Nagesh Nandiraju

Papers

Wireless Mesh Networks: Current Challenges and Future Directions of Web-In-The-Sky

Multipath Routing in Wireless Mesh Networks

Achieving Load Balancing in Wireless Mesh Networks Through Multiple Gateways

Supporting MAC layer multicast in IEEE 802.11 based MANETs: issues and solutions

A novel queue management mechanism for improving performance of multihop flows in IEEE 802.11s based mesh networks