.FLYINGHEAD WIRELESS INFRASTRUCTURE
.TITLE A focus on the challenges of mobile ad-hoc networks
.AUTHOR Humayun Bakht
.SUMMARY Although there are numerous benefits to the mobile ad-hoc network, due to their nature, they’re vulnerable and not deployable on a large scale because of the limits of technology. This article highlights some of the technical aspects of mobile ad-hoc networks with a brief discussion of the mechanisms currently in use, and how they overcome the challenges posed by this technology.
.OTHER
Our future living environments are likely to be based upon information resources provided by the connections of various communication networks for users. New devices like personal digital assistants, mobile phones and handhelds are advancing information processing and accessing capabilities with mobility. Moreover, traditional homes appliances and "gadgets," such as digital cameras, washing machines, cooking ovens and refrigerators — with computing powers attached — will extend the field to a fully pervasive computing environment. In the near future, mobile computing environments are expected to be based on recent advancements in computing and mobile technology. Next generation mobile systems will include both infrastructured wireless networks and infrastructureless mobile ad-hoc network.
A peer-to-peer or a mobile ad-hoc network is a collection of mobile nodes connected together over wireless medium without any fixed infrastructure. The special features of mobile ad-hoc networks bring the technology great opportunities together with different challenges. Challenges in the area of mobile ad-hoc network include security, dynamic network topology, routing, quality of service, and power efficiency.
One of the primary concerns is to provide secure communication between mobile hosts in a hostile environment. Unique characteristics of mobile ad-hoc networks pose various challenges to the security design, such as open peer-to-peer network architecture, a shared wireless medium and a high dynamic topology. These challenges raised the requirement of developing security solutions that achieve wider protection and desirable network performance. The wireless channel in a mobile ad-hoc network is accessible to both legitimate network users and malicious attackers. There is no standard security mechanism in a mobile ad-hoc network from the security design perspective to address this issue.
Since mobile ad-hoc networks do not have any centrally administrated secure routers, chances are good that attackers can easily exploit or possibly disable a mobile ad-hoc network, if no security mechanism is adopted. In general, security goals in mobile ad-hoc networks are gained through cryptographic mechanisms, such as public key encryption or digital signature. These mechanisms are supported through centralized key management where trusted certificate authority (CA) provides public key certificate to mobile nodes in order to develop mutual trust between them. Any disturbance with CA can easily affect the security of the entire network.
Due to the dynamic nature of a mobile ad-hoc network, it suffers with frequent topology changes. The network topology may change rapidly and unpredictably and the connectivity among the terminals may vary with time. The mobile nodes in the network dynamically establish routing among themselves as they move about; moreover a user in the mobile ad-hoc network may not only operate within the ad-hoc network, but may require access to a public fixed network. Mobile ad-hoc networks therefore should be able to adapt the traffic and propagation conditions as well as the mobility patterns of the mobile network nodes.
Routing is the process of information exchange from one host to the other host in a network. It is an important aspect; an effective routing mechanism is required to establish a smooth transmission across the network. Since the topology of the network is constantly changing, the issue of routing packets between any pair of nodes becomes a challenging task in mobile ad-hoc networks.
Quality of service refers to the ability of a network to provide a more reliable service to selected network traffic. Providing quality of service levels in a constantly changing environment is a challenge. The inherent stochastic nature of communications quality in a mobile ad-hoc network makes it difficult to offer fixed guarantees on the services offered to a device. An adaptive quality of service must therefore be implemented over the traditional resource reservation to support the multimedia services in mobile ad-hoc network.
For most of the light-weight mobile terminals, the communication-related functions should be optimized to save unnecessary power consumption. Wireless ad-hoc networks pose a different challenge for designing power efficient systems. Due to the absence of an infrastructure, each node in an ad-hoc network also acts as a router. For an ad-hoc network to exist, nodes have to be at least in the reception mode most of the time. Ad-hoc networks should be able to balance traffic load among nodes such that power constrained nodes can be put into a sleep mode while traffic is routed through other nodes.
In conclusion, mobile ad-hoc networks have several advantages over traditional wireless networks including ease of deployment, speed of deployment, and decreased dependence on a fixed infrastructure. Mobile ad-hoc networks constitute an emerging wireless networking technology for future mobile communications. In moving forward towards fulfilling this opportunity, the task of finding good solutions for these challenges will play a critical role in achieving the eventual success and potential of mobile ad-hoc network technology.
.BIO Eng. Humayun Bakht is pursing his Ph.D at the School of Computing and Mathematics in Liverpool at John Moores University. Prior to his current course of studies, he has successfully completed his MSc Software Engineering and BSc Electronics Engineering from University of Liverpool UK and Sir Syed University of Engineering and Technology in Karachi, Pakistan. Humayun’s research interest is mobile ad-hoc networks, in particular, the development of a new routing algorithm for this type of networking.
