The Study Of Energy-Efficient And Delay-Sensitive Node Scheduling In WSN

Wireless sensor network (WSN) is a new type of wireless network. It can carry on the real-time monitor to the specified area and provide data acquisition, processing and transmission to users. WSN have a broad application prospect in the fields of military, industry, environment and anti-terrorism. Wireless sensor network node has many characteristics, such as self-organization, easy to damage, low energy, not easy to replace, etc. So saving energy has been research hot spot problems and important goals.Duty cycling is widely used to save energy in WSN, which make the node close its radio when it does not need to send and receive data. But that could produce a lot of latency. Most of the collected data needs to be in a timely manner to the client, thus saving energy at the same time reduce delay becomes the focus of research and the difficult problem.According to above problem, two new energy-efficient and delay-sensitive node scheduling schemes has been proposed to choose the next hop based on a lot of analysis and comparison of various of the node scheduling methods:the scheme Energy-Balance and Delay-Sensitive (EBDS) and the scheme Minimum Delay Scheme (MDS).EBDS considers the scene of random node distribution and needs not to know the geographical information to increase lifetime of network. In a WSN with duty cycling, the shortest path could not obtain the smallest network latency all the time. EBDS combines the advantages of saving energy by using duty cycling with the advantages of minimum delay through the shortest path to choose the next hop. Within the defined time threshold, it chooses the shortest path of nodes as the next hop. On the contrary, it chooses the node which first woke up. It can obtain higher lifetime compensated by some delay can be tolerated. Calculations and simulation results show that EBDS was able to control delay within an acceptable range while effectively increases the lifetime of the network.MDS considers the scene of random node distribution and needs not to know the geographical information to minimum delay of network under the condition of limited energy. MDS selects the node whose remaining energy was in the limited range and had the minimum delay. Through the analysis and calculation of energy and delay of nodes, the cost function was obtained to calculate the node energy threshold. Calculations and simulation results show that MDS can control the lifetime of the network within an acceptable range while effectively minimizing network delay.To sum up, duty cycling is a common way to save energy. Balance the trade off energy saving and network delay by node scheduling is the important and difficult problem. The proposed scheme EBDS and MDS, were able to effectively improve the lifetime of network while reducing the network delay.