Challenges in Wireless/ Mobile Ad hoc NETworks (MANET)

As we can see that there are many application areas where Ad hoc networks can be used to benefit the human being, there has been a tremendous research work in this direction. However, still there are many challenging issues which need particular attention from research community.

Here we discuss some of the problems faced by this infrastructure-less wireless communication technology. Some of the main issues are:

• Scalability

• Quality of service

• Client server model shift

• Security

• Energy conservation

• Node cooperation

• Interoperation

Scalability: Most of the Ad hoc network applications imply no bound on the network size. In other words, any number of wireless nodes and enter or leave the network. However, if the number of nodes keeps increasing the resultant bandwidth available to a node within the network will decrease by the following formula:

Because the jobs like node discovery, route acquisition, service location and many of the handshakes required during establishment of a connection between nodes occupies bandwidth. Therefore, scalability is one of the great challenges being faced by Ad hoc networks

Quality of service: Most system works on the principle of best effort delivery service. Best-effort delivery describes a network service in which the network does not provide any guarantees that data is delivered or that a user is given a guaranteed quality of service level or a certain priority. In a best-effort network all users obtain best-effort service, meaning that they obtain unspecified variable bit rate and delivery time, depending on the current traffic load.

Quality of Service parameters:

•      Delay

•      Jitter

•      Bandwidth

•      Packet Loss Probability

Client server model shift: Internet depends on client server model, where the information request from client is served by the Servers available in the network. In contrary to this in Ad hoc network, there is no infrastructure to support this kind of model, therefore, a suitable model which may fit in the infrastructure less type of network is needed.

Security: Like all the wireless technologies, signals being exchanged between the nodes use electromagnetic waves which are prone to various detrimental effects like eavesdropping, spoofing, fading etc.

Energy conservation: In some specific applications like in sensor network, the size of the node being used in Ad hoc network is so small that cannot carry large batteries to support communication for a long time. In some situation, Ad hoc nodes are designed to be used only once and than they are thrown away. In both of the case, the battery life plays an important role. To enhance the battery time of nodes in Ad hoc network, various maximization techniques keeping node or complete network into mind are being studies and they require further investigation to bring even better battery performance of the node and network.

Node cooperation: The survival of Ad hoc network depends on mutual receiving and forwarding the messages on behalf of each other. This mutual cooperation is sometimes broken if there are some of the nodes selfish or malicious nodes in the network. To handle such type of nodes in the network, some policies of reward and penalty on the nodes is required to be studied.