Wireless sensor sensor networks lead to faults and errors by sensitivity of the sensor nodes. For solving this problem, first i have discuss the faults or the types of failure in network, describe the approaches of fault management . Various effective algorithms or adaptive fault tolerant mechanisms are designed till now to achieve a good fault management. In this paper we will discuss already implemented fault management approaches and Limitations of these approaches and try to recover the faults by the concept of mobile agents.
A wireless sensor network is a collection of many sensor nodes which has a capability of wireless communication and sensing the network.Wireless sensor network ...view middle of the document...
We Categorize these existing approaches according to different phases of fault management architecture that are
A) Fault Detection
Fault detection process helps that the services being provided are functioning properly.Fault detection approaches are classified into two types
1) Centralized approaches
In this approach ,most of the task are performed by central manager or base station(sink node) which have powerful resources(eg. Energy,Computing, and Memory etc).base Station use models to detect faults and life of an individual sensor node.The base station construct the map of the network with the help of routing update message providing a methods for recovering corrupted routes. Sympathy uses algorithm to minimise the number of communication messages, a Sympathy node can transmit the important events to base station.WinMS Warfighter Information Network Management System compares the current and previous state of sensor nodes against overall network information model to detect the faults.
Drawbacks of centralized approaches
This centralized approach provides good fault management while it is not suitable for large scale networks.
Another drawback is that the central controller becomes a single point of data traffic concentration and hence consumes large amount of energy of the nodes.
Third, this central controller becomes a single point of failure for the entire network. If this central controller fails due to
some error whole process disturbs.
2) Distributed Approaches
This approach distribute management functions throughout the network .A local node can take decision by itself, some of the messages may need to be delivered to the central manager. This approach conserve a lot of sensor node energy.
Now ,the clustering uses to creates energy balanced application for wireless sensor networks. It divides the whole network into a group of sensor nodes called clusters where one node is selected as a cluster head(CH) ,which has its associated sensor nodes called cluster members.CH executes different fault management functions to detect fault inside cluster proposed by Chessa .
Advantages of Distributed approach over the centralized approach, In this approach management responsibilities are transferred more towards the sensor nodes ,instead of a central manager,which ultimately makes the network more reliable and self-managed.
B) Fault Diagnosis
Now Fault diagnosis is the second phase of fault management,It identify the real cause of faults.Many methods already given for finding the location and cause of that particular fault, and how can we find it.
Where the fault is located?
What type of fault it is like node failure, link failure, traffic congestion , energy depletion etc?
How does a fault occurs by environment changes, hacker attacks, protocol implementation etc.
S. Babaie  presents the design of a decentralized fault diagnosis for a wireless sensor networks. Their system distinguish between multiple root causes of degraded...