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A Survey and Comparison of Various Routing Protocols of Wireless Sensor Network (WSN) and a Proposed New TTDD Protocol Based on LEACH Md. Habibe Azam1, Abdullah-Al-Nahid2, Md. Abdul Alim3, Md. Ziaul Amin4 1
Khulna University, School of Science, Engineering and technology Electronics and Communication Engineering Discipline Bangladesh
[email protected]
2
Khulna University, School of Science, Engineering and technology Lecturer, Electronics and Communication Engineering Discipline Bangladesh
[email protected]
3 Khulna University, School of Science, Engineering and technology Assistant Professor, Electronics and Communication Engineering Discipline Bangladesh
[email protected] 4
Khulna University, School of Science, Engineering and technology Lecturer, Electronics and Communication Engineering Discipline Bangladesh
[email protected]
Abstract: In wireless sensor network, the lifetime of a sensor node depends on its battery. By energy efficient routing protocol, it can increase the lifetime of the network by minimizing the energy consumption of each sensor node. Some energy efficient protocols have been developed for this purpose. Among those, we have made a survey on TTDD, LEACH, PEGASIS, SPIN and TEEN on the basis of some basis of some important evaluation matrix. Beside this, in this paper we have proposed new Two Tier Data Dissemination (TTDD) based on LEACH.
Keywords: WSN, Cluster, Protocol, TTDD, LEACH.
efficient routing protocol. Moreover, our proposed new TTDD protocol will save the lifetime of the sensing node. The reminder of this paper is organized as follows, in section 2, we briefly discuss the selected protocols, among which we have done the survey and made the comparative list. Section 3 represents the comparative list. we introduce my proposed new TTDD protocol and its advantage in section 4. Finally, concluding remarks are given in section 5.
2. Selected Protocols
1. Introduction Wireless sensor network (WSN) [1], [6] consists of small tiny devices called sensor nodes distributed autonomously to monitor physical or environmental conditions at different locations. These sensor nodes sense data in the environment surrounding them and transmit the sensed data to the sink or the base station. To transmit sensed data to the base station affects the power usage of sensor node. Typically, wireless sensor network (WSN) contain a large number of sensor nodes and these sensor nodes have the ability to communicate with either among each other or directly to the base station. For this reason energy plays a vital role in WSN and as much as possible less consumption of energy of each node is an important goal that must be considered when designing a routing protocol for WSN. Many routing protocol have been developed for this purpose. In this paper, we have made a survey among some selected protocols and made a comparative list of those protocols which will help to develop the new energy
2.1 TTDD Two-Tier Data Dissemination (TTDD) approach is used to address the multiple mobile sink problems. TTDD design uses a grid structure so that only sensors located at grid points need to acquire the forwarding information such as query and data [2]. When a node sense an event than the source node proactively forms a grid structure throughout the sensor field and sets up the forwarding information at the sensors closest to grid points. After forming this grid structure, a query from a sink traverses two tiers to reach a source. The lower tier is within the local grid square of the sink's current location and the higher tier is made of all the dissemination nodes at grid points from source to sink. The sink floods its query within a cell. Fig.1 shows the total procedure. It is assumed that in TTDD’s design sensor nodes are both stationary and location-aware. For the static sensor’s locations TTDD can use simple greedy geographical forwarding to construct and maintain the grid structure with low overhead and their locations awareness TTDD can tag the sensing data [3], [4], [5].
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Set-up Phase CH selection is done by considering two factors. First, the desired percentage of nodes in the network and second the history of node that has served as CH. This decision is made by each node n based on the random number (between 0 and 1) generated. If the generated random number is less than a threshold value T (n), then the corresponding nodes becomes CH for that round. The threshold value T (n) is calculated from equation 1as
(1) Figure 1. TTDD protocol. When a sink moves more than a cell size away from its previous location, it performs another local flooding of data query which will reach a new dissemination node. Along its way toward the source this query will stop at a dissemination node that is already receiving data from the source. This dissemination node then forwards data downstream and finally to the sink. In this way, even when sinks move continuously, higher-tier data forwarding changes incrementally and the sinks can receive data without interruption. Thus TTDD can effectively scale to a large number of sources and sinks. 2.2 LEACH Low Energy Adaptive Clustering Hierarchy (LEACH) is the first hierarchical cluster-based routing protocol for wireless sensor network. In LEACH the nodes are partitions into clusters and in each cluster there is a dedicated node with extra privileges called Cluster Head (CH). This CH creates and manipulates a TDMA (Time division multiple access) schedule for the other nodes (cluster member) of that cluster. Those CHs aggregate and compress the sensing data and send to base Station (BS) [7]. Thus it extends the lifetime of major nodes as shown in Fig. 2. Base Station Cluster-head Cluster Cluster member
Figure 2. LEACH protocol. This protocol is divided into rounds [6]; each round consists of two phases. Set-up Phase (1) Advertisement Phase (2) Cluster Set-up Phase Steady-state Phase (1) Schedule Creation (2) Data Transmission
Where P is the desired percentage of cluster-head, r is the number of round and G is the set of nodes that have not been cluster-heads in the last 1/P rounds. Nodes that have been cluster heads cannot become cluster heads again for P rounds. Thereafter, each node has a 1/p probability of becoming a cluster head in each round. In the following advertisement phase, the CHs inform their neighborhood with an advertisement packet that they become CHs. NonCH nodes pick the advertisement packet with the strongest received signal strength. In the next cluster setup phase, the member nodes inform the CH that they become a member to that cluster with "join packet" contains their IDs using CSMA. After the clustersetup sub phase, the CH knows the number of member nodes and their IDs. Based on all messages received within the cluster, the CH creates a TDMA schedule, pick a CSMA code randomly, and broadcast the TDMA table to cluster members. After that steady-state phase begins. Steady-state phase Nodes send their data during their allocated TDMA slot to the CH. This transmission uses a minimal amount of energy (chosen based on the received strength of the CH advertisement). The radio of each non-CH node can be turned off until the nodes allocated TDMA slot, thus minimizing energy dissipation in these nodes. When all the data has been received, the CH aggregate these data and send it to the Base Station (BS). LEACH is able to perform local aggregation data in each cluster to reduce the amount of data that transmitted to the BS. 2.3 PEGASIS Power Efficient Gathering in Sensor Information System (PEGASIS) is an energy efficient protocol and it is guaranteed by two characteristics [8], only one node communicates at a time with the base station, and the rest of the nodes communicate locally only with their neighbours. Each node communicates only with the closest neighbour by adjusting its power signal. By using signal strength, each node measure the distance to neighbourhood nodes in order to locate the closest nodes. After chain formation PEGASIS elects a leader from the chain in terms of residual energy in every round. The leader collects data from the neighbours to transmit to the base station. For this reason, the average energy spent by each node per round is reduced. Unlike LEACH, PEGASIS avoids cluster formation and uses only
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one leader in a chain to transmit to the BS instead of multiple CHs. This approach reduces the overhead and lowers the bandwidth requirements from the BS. Fig. 3 shows that only one leader node forward the data to the BS.
Figure 3. PEGASIS protocol. 2.4 SPIN Sensor Protocol for Information via Negotiation (SPIN) [7] is one of the first data-centric dissemination protocols for wireless network. The target scenario is a network where one, several, or possibly all nodes have data that should be disseminated to the entire network. This negotiation replaces the simple sending of data in a flooding protocol by a three step process. First, a node that has obtained new data either by local measurements or from some other nodes, advertises the name of this data to its neighbours. Second, the receiver of the advertisement can compare it with its local knowledge and if the advertised data is as yet unknown, the receiver can request the actual data. If the advertisement describes already known data (for example, because it has been received via another path or another node has already reported data about the same area), the advertisement is simply ignored. Third, only once a request for data is received, the actual data is transmitted. Fig. 4 represents the working procedure of SPIN protocol.
The nodes sense their environment continuously. The first time a parameter from the attribute set reaches its hard threshold value; the node switches on its transmitter and sends the sensed data. The sensed value is stored in an internal variable in the node, called the sensed value (SV). The nodes will next transmit data in the current cluster period, only when both the following conditions are true. 1. The current value of the sensed attribute is greater than the hard threshold. 2. The current value of the sensed attribute differs from SV by an amount equal to or greater than the soft threshold. Whenever a node transmits data, SV is set equal to the current value of the sensed attribute. Thus, the hard threshold tries to reduce the number of transmissions by allowing the nodes to transmit only when the sensed attribute is in the range of interest. The soft threshold further reduces the number of transmissions by eliminating all the transmissions which might have otherwise occurred when there is little or no change in the sensed attribute once the hard threshold.
3. Comparison In this section we present the comparison among the above protocol based on their various evaluation matrices [10]. Table 1. Comparison among the protocols Routing Protocol TTDD
Power Usage Ltd
Data Aggregation No
Scalability
Query Based
Over hade
Ltd
Yes
Low
LEACH
High
Yes
Good
No
High
PEGASIS
Max
No
Good
No
Low
SPIN
Ltd
Yes
Ltd
Yes
Low
TEEN
High
Yes
Good
No
High
4. Proposed new TTDD
Figure 4. SPIN protocol. 2.5 TEEN Threshold sensitive Energy Efficient sensor Network protocol (TEEN) [9] is targeted at reactive networks. In this scheme, at every cluster change time, in addition to the attributes, the cluster-head broadcasts to its members. Hard Threshold (HT): This is a threshold value for the sensed attribute. It is the absolute value of the attribute beyond which, the node sensing this value must switch on its transmitter and report to its CH. Soft Threshold (ST): This is a small change in the value of the sensed attribute which triggers the node to switch on its transmitter and transmit.
Main Features Our proposed routing protocol includes the following features: • Sensor nodes are homogeneous and energy constrained. • Sensor nodes are stationary, the BS is mobile and located near from the sensing area. • Each node periodically senses its nearby environment and would like to send its data to the base station. • A server is used for building a location database of sensor node. • At first the total area is divided into grid when a node senses any event and then there form a cluster keeping that node as CH. • Data fusion or aggregation is used to reduce the number of messages in the network. Assume that
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combining n packets of size k results in one packet of size k instead of size nk. • Using TDMA, cluster sends their data to the CH. The routing process can be organized into two phases, grid construction phase and cluster construction phase. Grid Construction Phase The sensing node builds a grid structure throughout the sensor field. The grid size as R×R, where R is a sensor node’s radio range. All sensor nodes in a grid are within their radio range. It sets up the forwarding information at the sensors closest to grid points. The sink floods its query within a cell. When the nearest dissemination node for the requested data receives the query, it forwards the query to its upstream dissemination node toward the source as like as TTDD. This query forwarding process provides the information of the path to the sink, to enable data from the source to traverse the query but in the reverse order. Location of all grid point through which the data is disseminated for the first time are stored in server. Cluster Construction Phase After the grid construction phase, server will receive the location of first time data dissemination grid point. Now the node which first create the grid structure, form cluster containing a cluster head whose role is considerably more energy intensive than the rest of the nodes. For this reason, nodes rotate roles between CH and ordinary sensor throughout the lifetime of the network. At the beginning of each round every node chooses a random number. If this random number is less than calculated thresholds then the node become a CH, else it does not (according to LEACH). Once a node becomes a CH, it cannot become a CH for a certain number of rounds. The threshold value depends upon the percentage of nodes wanted as CH and the number of rounds elapsed. Fig. 5 represents the total protocol.
Figure 5. Proposed new TTDD based on LEACH.
5. Advantage Advantages of the proposed protocol • Lifetime of sensing node is greater than TTDD. • Node consumes less energy than TTDD by aggregating the sensing data. • Data quality is batter than TTDD.
6. Conclusion Every protocol has some advantages and disadvantages but if we classify protocol according to their application and design those protocols only for specific purpose, then it will be energy efficient otherwise not.
References [1]
J. M. Kahn, R. H. Katz, and K. S. J. Pister, "Next Century challenges: Mobile networking for smart dust.” [2] Haiyun Luo, Fan Ye, Jerry Cheng, Songwu Lu, Lixia Zhang, “TTDD: A Two-tier Data Dissemination Model for Large-scale Wireless Sensor Networks”, UCLA computer science depertment, Los Angeles, CA 900095-1596. [3] S.Bassgni, “Distributed clustering for Ad Hoc Networks”International Symposium on parallel Architechtures, Algorithms and Networks. (ISPAN’99). [4] J. Hightower and G. Borriello, “Location Systems for Ubiquitous Computing”. IEEE Computer Magazine, 34(8):57{66, 2001}. [5] A. Ward, A. Jones, and A. Hopper, “A New Location Technique for the Active Oce”. IEEE Personal Communications, 4(5):42{47, 1997}. [6] Wendi Beth Heinzelman, “Application-specific protocol architechtures for wireless networks” Massachusetts Institute of Tchnology, June, 2000. [7] Mark A. Perillo and Wendi B. Heinzelman, “Wireless Sensor Network Protocols”. [8] Laiali Almzaydeh, Eman Abdelfattah, Manal Al-zoor and Amer Al-Rahayfeh, “Performance evaluation of routing protocols in wireless sensor networks” International Journal of computer Science and Information Techonology , Volume 2, Number 2, April 2010. [9] Arati Manjeshwar and Dharma P.Agrawal, “TEEN: A routing protocol for enhanced efficiency in wireless networks” Uniersity of Cincinnati, Cincinnati, OH 45221-0030. [10] P.T.V. Bhuvaneswari and V.Vaidehi, “Enhancement techniques incorporated in LEACH- a survey”, Indian Journal of Science and technology, Vol. 2, No. 5 (May 2009), ISSN: 0974-6846.
