Having understood the creation and working of the network and its topology, it is time to understand the problems one can face in this exercise and methods to overcome them.
Implementing a wireless mesh network poses several challenges in terms of achieving high performance, scalability, security and so on.
Since in a wireless mesh, each node serves both as a user and router of the network, it opens up the network to a variety of attacks such as physical attacks
(theft of laptops and large number of access points) DOS attacks, Gray, Black and wormhole attacks etc, which need to be considered while designing the network.
These problems persist at all layers.
While implementing and testing the mesh network, we faced the following issues:
Coverage:
We found that the distance between nodes that can communicate as part of the network is not deterministic.It varies depending on the physical environment of the participating nodes.Between the same two nodes, the radius of coverage changes with physical parameters of the surrounding environment. Ideally, the network should account for change in such physical parameters so as to be able to function optimally in all environments. This is particularly useful as it eliminates the need to configure a network separately for each application.
Performance and Scalability:
We find that the delay in communication between any two nodes in the network increases with the total number of participating nodes. Thus, the performance of the network drops with the addition of more nodes due to the reasons explained above. This also means that the network is not suitable for applications where the total number of nodes in large and is susceptible to change over time(due to dynamic addition of nodes).
Interference due to external networks:
Since there is no physical separation of media, there is no simple mechanism to prevent
other networks from interfering with the one under observation. This affects the performance, coverage and scalability of the network as well.
Although our experiment did not involve study of security aspects of the network, it is evident that the communication within the network is not very secure. Also, employing a wireless mesh is only suitable for applications with sufficient resources at disposal. Since the effects of interference cannot be easily eliminated, there is a large possibility of poor performance of the network for most applications. While allotting separate channels or adding more spectrum for communication does help, given the number of wireless technologies around, this comes at a significant cost.
Thus, the wireless mesh mode of communication must be chosen wisely – keeping the above constraints and challenges in mind for the intended application.
AD-HOC SENSOR NETWORKS 