Lifetime Extension of Border Nodes in SMAC ... - Semantic Scholar
Lifetime Extension of Border Nodes in SMAC-based Wireless Sensor Networks by Unifying Multiple Sleep Schedules among Adjacent Virtual Clusters Woonsik Lee
Daewon Lee
Hwang Soo Lee
Department of EECS, KAIST Daejeon, Korea
Department of EECS, KAIST Daejeon, Korea
Department of EECS, KAIST Daejeon, Korea
[email protected]
[email protected]
[email protected]
ABSTRACT
2. S-MAC OVERVIEW
In this paper, we propose a powerful but simple algorithm, termed as Schedule Unifying Algorithm (SUA), to minimize energy consumption by border nodes in sensor-MAC (S-MAC) based wireless sensor networks. SUA minimizes energy consumption by unifying the multiple listen and sleep schedules. We use NS-2 to implement and evaluate our algorithm. The experimental results show SUA incorporated S-MAC based nodes consume less energy thereby extends the lifetime 1.7 to 2.5 times more than that of SMAC based border nodes. Consequently, this prolongs the time period over which two or more virtual clusters can communicate via a border node and therefore extends the lifetime of overall network.
S-MAC protocol reduces energy consumption by putting the nodes in sleep state periodically. The basic scheme is shown in figure 1.
Figure 1. Periodic Listen and Sleep.
Categories and Subject Descriptors
Each node goes to sleep for a specified amount of time, and then wakes up and listens to see if any other node wants to communicate. How does a node determine its schedule? After sensor nodes are deployed, they start to listen for a certain amount of time. If a node does not hear any SYNC packet which contains the information about listen and sleep schedule, it chooses its own schedule and becomes a synchronizer. If a node who receives a SYNC packet from a neighbor, it follows the schedule from the packet and becomes a follower. The period for each node to send a SYNC packet is called synchronization period.
H.1.0 [Models and Principles]: General
General Terms: Algorithms, Design Keywords: SMAC, Sensor Networks 1. INTRODUCTION Wireless sensor networking is an emerging technology that has attracted tremendous amount of attention and media publicity from both the research community and industry [1]. A typical sensor network consists of large number of tiny, battery-powered nodes with low-range radios, and low-cost processors and sensors. These devices organize to form a multi-hop wireless network and coordinate together to accomplish a common objective. Once the sensor nodes are deployed, it is often impossible to recharge. Thus, energy efficiency is one of the most important requirements.
A group of nodes following the same schedule form a virtual cluster as shown in figure2. The nodes D1 and B2 are neighboring nodes following two different schedules. Therefore, they may never find each other due to completely different schedules. Periodic neighbor discovery (PND) solves this problem. During PND each node periodically listens for the entire synchronization period. The node D1 or B2 who finds firstly the existence of the other node following different schedule will adopt the newly known schedule and becomes a border node.
Sensor-MAC (S-MAC) is a medium access control protocol designed particularly for wireless sensor networks [2]. In S-MAC, a node bordering two or more virtual clusters adopts different listen and sleep schedules and becomes a border node. The border nodes frequently go to listen state to relay packets from one virtual cluster to the other. Since, the border nodes consume more power than the other nodes, they will be discharged more quickly. Consequently, each network cluster which adopts its own schedule becomes not able to communicate with others. We present a scheme to reduce energy consumption by border nodes in S-MAC based wireless sensor networks. The schedule unifying algorithm unifies multiple schedules adopted by a border node and extends lifetime of the node by reducing the energy consumption.
Figure 2. Virtual Cluster and neighboring nodes. Node D1 and B2 are neighboring nodes.
Copyright is held by the author/owner(s). PE-WASUN’05, October 10–13, 2005, Montreal, Quebec, Canada. ACM 1-59593-182-1/05/0010.
267
3. SCHEDULE UNIFYING ALGORITHM The main idea is that the border node selects one schedule which belongs to the higher node address of synchronizers and it makes all of its neighbor nodes to border nodes and becomes itself a "nonborder" node. The whole steps are indicated in figure 3. Set the next neighbor that is not adopting the synchronizer’s schedule as the current target neighbor
Start
Listen for SYNC Packet at least synchronization period
Find any schedule?
Becoming Follower
Yes
No
Trials of sending the unifying packet to the current target neighbor < Retry counter ?
No
No Yes Becoming Syncronizer
Send unifying packet to the current target neighbor by unicasting. (RTS/CTS)
Figure 4. Simulation topology and result. Increase the retry counter by 1
No
In PND or normal state, the node receives a different schedule?
Ack received ?
Yes
Yes
Adopt both schedules. (becoming a border node)
Received acks of all the neighbors ?
The result shows that if the SUA is applied, the network lifetime is extended from 2600sec to 4400sec. This is about 1.73 times better than the PND only case. In three virtual clusters topology, we can also show that the lifetime can be extended by 2.5 times.
No
5. CONCLUSION It is able to greatly enhance the network lifetime by eliminating all the border nodes. This means the unification of the listen and sleep schedules. SUA makes this. The simulation result ensures the wellworking of SUA.
Yes Generate unifying packet having the highest synchronizer ’s schedule as a target schedule
Unifying the schedules into the target schedule
6. ACKNOWLEDGMENTS This research was supported by the MIC(Ministry of Information and Communication), Korea, under the ITRC (Information Technology Research Center) support program supervised by the IITA(Institute of Information Technology Assessment)
Figure 3. Flow diagram of SUA.
7. REFERENCES
If all nodes follow the algorithm, the entire networks are finally synchronized with the schedule of the synchronizer having highest address. As expected, SUA is a simple and powerful algorithm for the implementation.
[1] Joseph M. Hellerstein, Wei Hong, Samuel R. Madden, ”The Sensor Spectrum: Technology, Trends, and Requirements,” UC Berkeley, Intel Research Berkeley, MIT. [2] Wei Ye, John Heidemann, Deborah Estrin. “Medium Access Control with Coordinated, Adaptive Sleeping for Wireless Sensor Networks”, USC/ISI TECHNICAL REPORT ISITR0567, JANUARY 2003
4. SIMULATION AND ANALYSIS In figure4 (a), after deployed, the node H and D are the first who have finished initial listening earlier than the other nodes to find any schedules and become synchronizers. As time goes, node G, I, J and B are following the schedule of synchronizer H. On the other hand, node A, C, E and F are following the schedule of synchronizer D. Boundary node of the two networks is node B. It means node B becomes border node after the first PND.
[3] Network Simulator – 2 : http://www.isi.edu/nsnam/ [4] Naneen Sait. “Critique of SMAC”, SSNS Spring 2003
268
Daewon Lee
Hwang Soo Lee
Department of EECS, KAIST Daejeon, Korea
Department of EECS, KAIST Daejeon, Korea
Department of EECS, KAIST Daejeon, Korea
[email protected]
[email protected]
[email protected]
ABSTRACT
2. S-MAC OVERVIEW
In this paper, we propose a powerful but simple algorithm, termed as Schedule Unifying Algorithm (SUA), to minimize energy consumption by border nodes in sensor-MAC (S-MAC) based wireless sensor networks. SUA minimizes energy consumption by unifying the multiple listen and sleep schedules. We use NS-2 to implement and evaluate our algorithm. The experimental results show SUA incorporated S-MAC based nodes consume less energy thereby extends the lifetime 1.7 to 2.5 times more than that of SMAC based border nodes. Consequently, this prolongs the time period over which two or more virtual clusters can communicate via a border node and therefore extends the lifetime of overall network.
S-MAC protocol reduces energy consumption by putting the nodes in sleep state periodically. The basic scheme is shown in figure 1.
Figure 1. Periodic Listen and Sleep.
Categories and Subject Descriptors
Each node goes to sleep for a specified amount of time, and then wakes up and listens to see if any other node wants to communicate. How does a node determine its schedule? After sensor nodes are deployed, they start to listen for a certain amount of time. If a node does not hear any SYNC packet which contains the information about listen and sleep schedule, it chooses its own schedule and becomes a synchronizer. If a node who receives a SYNC packet from a neighbor, it follows the schedule from the packet and becomes a follower. The period for each node to send a SYNC packet is called synchronization period.
H.1.0 [Models and Principles]: General
General Terms: Algorithms, Design Keywords: SMAC, Sensor Networks 1. INTRODUCTION Wireless sensor networking is an emerging technology that has attracted tremendous amount of attention and media publicity from both the research community and industry [1]. A typical sensor network consists of large number of tiny, battery-powered nodes with low-range radios, and low-cost processors and sensors. These devices organize to form a multi-hop wireless network and coordinate together to accomplish a common objective. Once the sensor nodes are deployed, it is often impossible to recharge. Thus, energy efficiency is one of the most important requirements.
A group of nodes following the same schedule form a virtual cluster as shown in figure2. The nodes D1 and B2 are neighboring nodes following two different schedules. Therefore, they may never find each other due to completely different schedules. Periodic neighbor discovery (PND) solves this problem. During PND each node periodically listens for the entire synchronization period. The node D1 or B2 who finds firstly the existence of the other node following different schedule will adopt the newly known schedule and becomes a border node.
Sensor-MAC (S-MAC) is a medium access control protocol designed particularly for wireless sensor networks [2]. In S-MAC, a node bordering two or more virtual clusters adopts different listen and sleep schedules and becomes a border node. The border nodes frequently go to listen state to relay packets from one virtual cluster to the other. Since, the border nodes consume more power than the other nodes, they will be discharged more quickly. Consequently, each network cluster which adopts its own schedule becomes not able to communicate with others. We present a scheme to reduce energy consumption by border nodes in S-MAC based wireless sensor networks. The schedule unifying algorithm unifies multiple schedules adopted by a border node and extends lifetime of the node by reducing the energy consumption.
Figure 2. Virtual Cluster and neighboring nodes. Node D1 and B2 are neighboring nodes.
Copyright is held by the author/owner(s). PE-WASUN’05, October 10–13, 2005, Montreal, Quebec, Canada. ACM 1-59593-182-1/05/0010.
267
3. SCHEDULE UNIFYING ALGORITHM The main idea is that the border node selects one schedule which belongs to the higher node address of synchronizers and it makes all of its neighbor nodes to border nodes and becomes itself a "nonborder" node. The whole steps are indicated in figure 3. Set the next neighbor that is not adopting the synchronizer’s schedule as the current target neighbor
Start
Listen for SYNC Packet at least synchronization period
Find any schedule?
Becoming Follower
Yes
No
Trials of sending the unifying packet to the current target neighbor < Retry counter ?
No
No Yes Becoming Syncronizer
Send unifying packet to the current target neighbor by unicasting. (RTS/CTS)
Figure 4. Simulation topology and result. Increase the retry counter by 1
No
In PND or normal state, the node receives a different schedule?
Ack received ?
Yes
Yes
Adopt both schedules. (becoming a border node)
Received acks of all the neighbors ?
The result shows that if the SUA is applied, the network lifetime is extended from 2600sec to 4400sec. This is about 1.73 times better than the PND only case. In three virtual clusters topology, we can also show that the lifetime can be extended by 2.5 times.
No
5. CONCLUSION It is able to greatly enhance the network lifetime by eliminating all the border nodes. This means the unification of the listen and sleep schedules. SUA makes this. The simulation result ensures the wellworking of SUA.
Yes Generate unifying packet having the highest synchronizer ’s schedule as a target schedule
Unifying the schedules into the target schedule
6. ACKNOWLEDGMENTS This research was supported by the MIC(Ministry of Information and Communication), Korea, under the ITRC (Information Technology Research Center) support program supervised by the IITA(Institute of Information Technology Assessment)
Figure 3. Flow diagram of SUA.
7. REFERENCES
If all nodes follow the algorithm, the entire networks are finally synchronized with the schedule of the synchronizer having highest address. As expected, SUA is a simple and powerful algorithm for the implementation.
[1] Joseph M. Hellerstein, Wei Hong, Samuel R. Madden, ”The Sensor Spectrum: Technology, Trends, and Requirements,” UC Berkeley, Intel Research Berkeley, MIT. [2] Wei Ye, John Heidemann, Deborah Estrin. “Medium Access Control with Coordinated, Adaptive Sleeping for Wireless Sensor Networks”, USC/ISI TECHNICAL REPORT ISITR0567, JANUARY 2003
4. SIMULATION AND ANALYSIS In figure4 (a), after deployed, the node H and D are the first who have finished initial listening earlier than the other nodes to find any schedules and become synchronizers. As time goes, node G, I, J and B are following the schedule of synchronizer H. On the other hand, node A, C, E and F are following the schedule of synchronizer D. Boundary node of the two networks is node B. It means node B becomes border node after the first PND.
[3] Network Simulator – 2 : http://www.isi.edu/nsnam/ [4] Naneen Sait. “Critique of SMAC”, SSNS Spring 2003
268
