AN ENERGY CONSUMPTION ANALYTIC MODEL FOR WIRELESS SENSOR MAC PROTOCOL

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ABSTRACT

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Some sensor products adopt IEEE 802.11-like MAC Protocol. However, IEEE 802.11 MAC is not a good solution for WSN.

S(Sensor)-MAC proposes enhanced schemes such as periodic sleep and overhearing avoidance to provide a better choice for sensor applications.

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This paper presents an analytic model for evaluating the energy consumption at nodes in a S-MAC based WSN.

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I. INTRODUCTION

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Sensor network lifetime will rely on the corresponding batteries of sensor nodes.

IEEE 802.11 is one of the dominating MAC Protocol in current times. However, the power control function of IEEE 802.11 can not satisfy the requirements of sensor network application.

In this paper, we propose an analytic model estimating energy consumption of sensor nodes adopting S-MAC.

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II. RELATED WORK

[1]-Measuring and reducing energy consumption of network interfaces in hand-held devices

[2]- An energy-efficient MAC protocol for wireless sensor networks

[3]- PAMAS: Power aware multi-access protocol with signalling for ad hoc networks Optimizing sensor networks in the energy-latency-density design space

Optimizing

[4]- sensor networks in the energy-latency-density design space,

[5]- University of california, berkeley, mica2 schematics

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II. RELATED WORK

[6]- An adaptive energy efficient MAC protocol for wireless sensor networks

[7]- An adaptive energy-efficient and low-latency MAC for data gatheringin sensor networks

[8]- Performance analysis of the IEEE 802.11 distributed coordination function

[9]- Redefining internet in the context of pervasive computing

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II. RELATED WORK

[10]- Performance analysis and enhancement for the current and future IEEE 802.11 MAC protocols

[11]- Performance of reliable transport protocol over IEEE 802.11 wireless LAN: Analysis and enhancement

[12]- Queueing analysis and delay mitigation in IEEE 802.11 random access MAC based wireless networks

[13]- Data gathering in sensor networks using the energy*delay metric

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III. S-MAC

In the conventional IEEE 802.11 protocol ,there are several disadvantages causing unnecessary energy waste.

1. Every nodes hears transmission of all neighboring nodes even if the packet is not destined to itself.

2. Besides, considerable control packet may increase overhead in energy consumption.

3. The last one is idle listening, a node keeping listening to possible traffic for itself all the time.

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IV. S-MAC ANALYTIC MODEL

Energy consumption of a node running S-MAC :

E(t) = NT (t)ET + NR(t)ER + TS(t)PS + TI (t)PI (1)

Energy consumption for transmitting a packet:

ET = PTx(tRTS + tdata) + PRx(tCS + tBO + tSL+tCTS + tACK + 3tSIFS + DIFS) (2)

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IV. S-MAC ANALYTIC MODEL

Energy consumption for receiving a packet:

ER = PTx(tCTS + tACK) + PRx(tRTS + tdata+3tSIFS + tDIFS) (3)

Number time the node sends packets:

NT (t) = λTt (4)

Number time the node receives packets:

NR(t) = λRt (5)

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IV. S-MAC ANALYTIC MODEL

S-MAC sensor node goes into sleep mode in three cases:① scheduled sleep time② Receiving a RTS frame from its neighboring nodes③ Receiving a CTS frame from its neighboring.

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IV. S-MAC ANALYTIC MODEL Sleep time Fig (6)

Idle Listening time Fig (7)

In S-MAC, the sleep schedule for a node will be synchronized with all its neighbors

psucc =nτ (1 − τ )n−1/1 − (1 − τ )n (8)

Extra idle period occurs when a node finishes a packet transmitting or receiving.

e= NI ×Tf rame/2 By deriving the unknowns in (1) using (2) (3) (4) (5) (6) (7) (8) (9) , we

can evaluate the energy consumption of a node in analytic method

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IV. S-MAC ANALYTIC MODEL

The chain-hop topology used in validating our analytic model:

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SinkSource

Fig. 1

IV. S-MAC ANALYTIC MODEL

Another topology used in validating our analytic model

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Source_00

Sink_1

Sink_0

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Source_11Fig. 2

V- ANALYTIC RESULT

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A. Model Valida-tion

Fig. 3The energy consumption of node 0 in Fig. 1 evaluated by analytic model and simulation

V- ANALYTIC RESULT

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Fig. 4The energy consumption of node 2 in Fig. 1 evaluated by analytic model and simulation

V- ANALYTIC RESULT

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Fig. 5The energy consumption of node 2 in Fig. 2 evaluated by analytic model and simulation

V- ANALYTIC RESULT

A grid topology used in analysis S-MAC based WSN design

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Fig. 6A grid topology used in analysis S-MAC based sensor network design

V- ANALYTIC RESULT

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Fig. 7Relative energy consumption,relative latency and relative energy*delay of total network

B. ENERGY EFFICIENCY OF S-MAC

In many sensor network applications, energy consumption is not the only important design issue.

Periodic sleep scheme in S-MAC saves energy while nodes are idle, but this scheme also introduce additional delay for waiting the reviver back to listening from sleeping.

Choosing a shorter duty cycle would decrease the idle listening time, but increase the latency.

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B. ENERGY EFFICIENCY OF S-MAC

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Fig. 8Relative energy consumption of total network of 20 chain-hops.

B. ENERGY EFFICIENCY OF S-MAC

According to formula (1),the energy consumption of S-MAC based sensor nodes can be devided into 4 parts:

① Sending packets② Receiving packets③ Idle Listening④ sleeping

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VI. CONCLUSION AND FUTUR WORK

This paper introduces an analytic model to estimate the energy consumption S-MAC

S-MAC saves energy but sacrifices latency. To achieve better energy efficiency than S-MAC, the future work includes the improvement of energy consumption and reduction of packet latency of S-MAC.

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