Energy Saving Strategy Based on SPIN Routing Protocol in Wireless Sensor Network

Oluwatuyi Rufus Abidakun†, Ryo Yamamoto†, Yoshiaki Tanaka†, ‡

†Global Information and Telecommunication Institute, Waseda University‡Research Institute for Science and Engineering, Waseda University

1. IntroductionWireless sensor networks are formed by a large number of wireless sensing nodes. The sensor nodes measure physical quantities such as temperature, position, humidity and pressure. The output of those sensor nodes are transmitted to the base station or gateway for data collection, analysis, and logging using wireless communication. Thus, end users may be able to receive and manage the data from sensors using console terminals [1].

Wireless sensor nodes are typically battery operated. Therefore, their energy is constrained. To maximize sensor nodes’ lifetime after its deployment, some aspects including circuits, architecture, algorithms, and protocols have to be energy efficient [2]. As concern this, WSNs need a different routing approach for their data in order to minimize energy consumption during transmissions. In this paper, we introduce SPIN-N protocol based on SPIN protocol as an energy-efficient routing protocol to send data message through neighbouring sensor nodes.

2. SPIN ProtocolSPIN [3] is a data-centric routing protocol. It is an adaptive protocol based on an idea that sensor nodes operate more efficiently. It can save transmission energy by sending metadata that describes a sensing data instead of sending the whole data unless it will be explicitly requested. In SPIN protocol, nodes use three types of message for communication:(1) ADV: When a node has new data to share, it

broadcasts an ADV message to its neighbouring nodes.

(2) REQ: If a node is interested in the ADV message, it sends a REQ message to request for the data.

(3) DATA: DATA message contains actual sensor data.Before sending a DATA message, a sensor broadcasts an

ADV to its neighbouring nodes. If a neighbouring node is interested in the ADV message, it sends back a REQ message for requesting the DATA message. After receiving the REQ message by the sensor node, the DATA message is sent to this neighbouring sensor node [4]. However, when a request is made for the DATA, the source node spends a lot of energy to transmit the DATA.

3. SPIN-N MethodTo save the energy consumption during transmission for DATA, we proposed SPIN-N protocol. SPIN-N protocol is

based on SPIN family of protocol. In SPIN-N, the source node calculates an energy cost of direct transmission and determines whether the transmission through the neighbouring node is more energy efficient.

Energy consumption of sensor nodes is paramount to the overall efficiency of the network. SPIN-N helps in maintaining the efficiency by saving nodes’ energy,

especially when the residual energy RE of the node is below a defined threshold of the initial energy. For the SPIN-N protocol we consider the first order radio model which is researched in [5]. The energy consumption per bit in transmission is given by

where Ee represents the energy consumption per bit in the transmitter circuitry and Eadn represents the energy consumption in transmission amplifier for transmit a single bit over a distance d [6]. The minimum output power required to transmit a signal over a distance d is proportional to dn where 2≤n<4 . The exponent n is closer to 4 for low-lying antennae and near-ground channels [4]. Hence, The total energy consumption for transmitting a K-bit packet is

The energy consumption for receiving a K-bit packet where Er is the energy requirement per bit for successful reception is

Using the above equations, we calculate the total energy consumption for direct transmission from source node a to destination node b as

and the total energy consumption for transmitting to node b through neighbouring node c is

where Rn(b) represents neighbouring node c’s reliability which prove the node existence in the network calculated by source node and destination node jointly. To guarantee neighbouring node’s reliability, a value 1 or 0 is assigned upon verification by the both nodes. The value assignment is done to confirm the validity of neighbouring node in the network. The reliability value 1 is assigned to neighbouring node only when the node responds to the beacon message from source and destination during periodic neighbour

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discovery phase. This approach prevents a malicious node from claiming neighbour relationship. After the calculation of the energy cost for transmission, a source node compares the cost for direct transmission and detoured transmission. If the latter cost is smaller, the source node selects the detoured route as a transmission route.

Fig. 1 SPIN-N Routing Strategy

Fig. 1 shows the example operation of SPIN-N protocol. When node B sends a REQ message to node A for the DATA message, node A calculates the estimated energy cost for actual data transmission to node B. If node A and node B have common neighbouring node, node A calculates the estimated energy cost to the node. In this example, node C would be the common neighbouring node. Subsequently, the estimated energy cost from node B to C is calculated. Then, the estimated transmitting cost from node A to B through node C Et{d(B,C,A),n} is compared with Et{d(B,A),n} which represents estimated transmitting cost from node A to B directly. If Et{d(B,C,A),n} is smaller than Et{d(B,A),n}, the link (B,C,A) would be used to send a DATA messages to node B. Before the route is used for data transmission, neighbouring node C’s reliability is also calculated by node A and B jointly. In order to guarantee node C’s reliability, both node A and B assigns a value 1 or 0 upon verification. The assigned reliability Rn(b) prevents a malicious node from claiming neighbour relationship.

4. Performance evaluationIn our work, we assume a model where the radio consumes Ee=50nJ/bit, Ea=100pJ/bit/m2 with K ranging from 2000-5000 bits. The distance d(a,b)=100m, d(a,c)=70m, d(c,b)=60m and Rn(b)=1. The initial energy of the source node is set to Ei=0.5J. The simulations have been done by MATLAB.

Fig. 2 and Fig. 3 show the simulation results. From the result, total energy consumption using SPIN-N protocol is smaller than SPIN protocol that does not use neighbouring node for data message transmission. This is because that SPIN protocol tries to send a data message directory to its destination. On the other hand, SPIN-N protocol tries to use its neighbouring node for detouring to reduce transmission energy. This also decrease the total energy consumption in the network since the average transmission distance is decreased by detouring long and non energy-efficient links among the networks.

5. ConclusionThe main goal of the proposed SPIN-N protocol is to save energy and extend the networks’ life time. Direct communication in SPIN protocol can be energy tasked, especially when the deployment of the sensor node is over a long period of time. SPIN-N protocol considers residual energy of a sensor node. SPIN-N protocol is based on SPIN protocol, however, it uses neighbouring nodes to reduce transmission distance for less energy consumption. By using SPIN-N protocol, it can reduce the total energy consumption of the entire network compared to direct communication. However, one major problem is if the residual energy of the neighbouring node is also below the defined threshold, node’s decision to support forwarding DATA might be crucial to the efficiency of SPIN-N protocol. Future work may be to work on this associated problem.

Fig. 2 Residual energy of sensor node A

Fig. 3 Total energy consumption

References

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[3] Z. Rehena, S. Roy and N. Mukherjee, “A modified SPIN for wireless sensor networks,” in Communication Systems and Networks (COMSNETS), Bangalore, January 2011.

[4] C. Erdal and C. Rong, Security in Wireless Ad Hoc and Sensor Networks, John Wiley & Sons, Chichester,UK, 2009.

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[5] J. Banerjee, S. K. Mitra and M. K. naskar, “Comparative study of radio models for data gathering in wireless sensor network,” International Journal of Computer Applications, vol. 27, no.4, pp. 51-57, August 2011.

[6] W. R. Heinzelman, A. Chandrakasan and H. Balakrishnan, “Energy-efficient communication protocol for wireless microsensor networks,” in Hawaii International Conference on System Sciences, Hawaii, June 2000.

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