# MB-OFDM-UWB Based Wireless Multimedia Sensor Networks for Underground Coalmine: A Survey
## 4 Other Research Issues
### Network Management  
Sensor nodes in underground coalmine WMSNs are large in numbers and restricted in resource, and the environment condition of monitoring regions is generally harsh. If no network management strategy is conducted in the process of network planning, deployment and maintenance, it will be difficult to realize effective monitoring on monitoring regions. The reason is that once the sensor network is deployed, maintaining a network utterly by man seems really hard and even impossible. Electromagnetic interference, different kinds of adverse environment conditions and limited energy of sensors all can be factors that lead to breakdowns or damages in sensor devices, thus making the whole network prone to malfunctions or even crashes.  
Network management for sensor network aims to realize the following requirements: (1) develop effective management strategies in light of the characteristics of sensor network; (2) monitor various status parameters in real time; and (3) realize self-judgment, self-maintenance and self-determination. Accordingly, by network management, sufficient utilization of network resource can be realized, and we can also provide reliable QoS for applications and satisfy the service requirements of multimedia monitoring in underground coalmine WMSNs.  
Typical framework for network management in WSNs includes BOSS [68] and MANNA [69]. BOSS (short for Bridge of the SensorS) can be regarded as an intermediary which is able to interpret and transfer messages between the UPnP controllers and the non-UPnP sensor nodes to be managed, while MANNA offer a unified framework for the strategy-based network management of WSNs [70; 71]. Network management protocols for WSNs mainly includes TopDisc and STREAM in sNMP which are used for extracting topology information of the network, the zone flooding scheme used in RRP, the Drip protocol introduced by SNMS, and FlexiMAC in WinMS [72; 73].  
In [11], the authors designed two working modes, namely the periodic inspection mode and interrupt service mode, for a coalmine environment monitoring system based on WSNs. The two modes correspond to the reactive monitoring and proactive monitoring in the management reactivity. Then, based on the data or events collected by the network, different management tasks can be distributed in the network. In addition, topology management, location management, energy management and fault management are also adopted in their system, ensuring the normal operation of coalmine WSNs. However, for coalmine WMSNs, the unreliable communications incurred by harsh environment of coalmine and various amounts and types of data brought by WMSNs, make it more challenging to design comprehensive frameworks and protocols for network management in coalmine WMSNs.  
However, the existing frameworks and protocols for network management in WSNs have not been fully functional, and the research work on network management in WMSNs is still few in number. Thus, in order to guarantee the efficient configuration, operation, administration, and maintenance of underground coalmine WMSNs, efficient frameworks for network management and corresponding protocols should be proposed, combined with specific applications of networks.