In the unattended nature of WSNs, it is important to have an infrastructure that provides indication of the system state. The reason for this is to identify sensor node failures, resource depletion, network partition, areas which have excessive periodic signal disintegration, and any other abnormalities. Such an infrastructure is important in WSNs as it can potentially provide an early warning of system failure, a corrective measure for non-optimal placement of sensor nodes, and it can also be used as a tool to monitor and maintain the network as a whole.
As with many other conventional computer systems, system states are normally deduced from log files. Hence, the sensor nodes must be able to report their states by transmitting their state information through multihop paths to a central computer for logging. However, the transfer of log data is often a long-term (normally throughout the network lifetime) and on-going process. If log data has the same transmission cycle as sensed data, then the network will be congested with both sensed and log data, and the sensor node will spend half its lifetime energy on transferring such log data. One technique to effectively collect log data from sensor nodes is to use data-aggregation on the log data (as used in [38]) to ensure they are sent within a long and acceptable interval, meaningful, useful, and compact in size.
Network management protocols in WSNs are often application specific, and depend much on the context that they are intended for and on the state variables (i.e. energy levels of sensor nodes, sensor node failures, workload of the network, etc) that we want to monitor. In manufacturing, there are several reasons we want an effective network management protocol in place in addition to the obvious reasons previously mentioned. One reason, for example, is to monitor areas in which signal disintegration is too periodic such that the signal disintegration period dominates the availability of the medium. In such a case, we can physically change the positions of any affected sensor nodes to different locations in the manufacturing plant where the medium is ``clearer''.