# Software Defined Networking for Improved Wireless Sensor Network Management: A Survey
## 2 WSN Management  
Management of WSN should allow for definition of a set of functions that promote productivity and integration in an organized manner of the configuration, maintenance, operation and administration of the components and services of the WSN [25]. Several management methods have been proposed to manage functionality in the architecture of WSNs [30]. These methods take into account WSN metrics such as energy consumption, system lifespan, data latency, system tolerance to faults, accuracy in data acquisition or the Quality of Service and security. WSN management should be simple and adhere to network dynamic behaviour, as well as provide efficiency in use of resources as proposed by [PERSON] et al. [25] in the MANNA (A management architecture for wireless sensor networks) architecture. The MANNA architecture considers management policies for WSN services, functions and models by looking at management of WSNs in three dimensions defining functionality abstractions:  
* WSN functionalities which include maintenance, configuration, sensor node operation (Sensing, processing, communication)
* Management levels which include application services and management of network elements (node clusters, data aggregation, network connectivity). * Management of functional areas such as security, fault monitoring, performance and configuration. In this paper the structure of WSN management schemes presented is based on the above protocols [30] and abstraction entities [25] however we re-categorise them according to functional relationships as follows:1. Network configuration management: All issues associated with network configuration and operation are categorised here. This includes protocol implementation, configuration of data acquisition, network service, network level programming issues. 2. Topology management: This management category handles issues related to the layout of the WSN. Management of sensor node location and distribution, network activity distribution, node to node communication including gateway elements fall under topology management. 3. QoS management: Data latency, system performance, fault tolerance, data acquisition accuracy are among the issues managed under this category to ensure an optimum WSN quality of service. 4. Energy management: All parameters regarding energy consumption in the network are categorised here including energy sources, energy consumption minimization and system lifespan in relation to available energy resources. 5. Security management: Considering the popularity of WSNs, more sensitive information is being transmitted over such networks thus it is necessary the network is protected from malicious attacks. This would most involve management of network security functionalities such as encryption (key distribution techniques), threat detection and recovery which are categorised here. 6. Maintenance management: Wireless sensor network aspects related to maintaining correct operation of the network are classified under this management category. Monitoring of network performance, energy levels and faults define some of these aspects. As shall be discussed depending on the availability of the management techniques for the categories above, WSNs can be tailored to meet at least one or more of the following design criteria:  
1. Energy Efficiency- This takes into account the ability of a system to conserve energy or allow operation on limited power for long periods resulting in improved network lifetime. 2. Robustness- This criteria ensures that a system performs as expected regardless of varying environmental conditions or design requirements [24]. A robust system should produce desirable performance despite network variations such as node failure, power outages and instabilities resulting from node mobility. An important characteristic of a robust management system is network reconfiguration [31]. 3. Scalability- WSN nodes are expected to scale up very large numbers therefore a scalable management system should function efficiently at any network scale.