TOPOLOGIES FOR POWER EFFICIENT WIRELESS SENSOR NETWORKS ---KRISHNA JETTI.

INTRODUCTION: A smart sensor is a collection of integrated sensors and electronics. A wireless smart sensor network node are constructed using these smart sensors, so these individual nodes can be resource-aware, and resource-adaptive. The fields in which these networks include are space exploration, medicine and many others. Many of the topologies proposed for wired networks cannot be used for wireless networks, for in wired networks, a higher dimension can be implemented by connecting the nodes in some fashion to simulate higher dimensions. Topologies that we are going to investigate for WSN’s are 1. LEACH 2. SPIN 3. DSAP

LEACH (Low-Energy Adaptive Clustering Hierarchy): 1. It is a new communication protocol that tries to evenly distribute the energy load among the network nodes. 2. This assumes that we have a finite amount of power and aims at conserving as much energy as possible despite a dynamic network. 3. It uses data compression to reduce the amount of data that must be transmitted to a base station.. SPIN (Sensor Protocols for Information via Negotiation): 1. It is a unique and complete set of protocols for energy-efficient communication among wireless sensors. 2. It incorporate two key ideas to overcome the network implosion caused by flooding, overlapping transmission ranges, and power conservation : negotiation and resource adaptation. 3. Using very small meta-data packets to negotiate, SPIN efficiently communicates with fewer redundancies than traditional approaches, dealing with implosion and overlap.

DSAP (Directional Source-Aware Protocol): 1. The routing works by assigning each node an identifier that places that node in the network. Each of the numbers tells how many nodes separate that node from the edge of the network through all possible directions 2. DSAP has many benefits when compared to the normal routing protocols  it contains embedded power considerations  uses no routing table.

HOW DOES IT WORK: SOURCE : Node 51 DESTINATION : Node 33 Source DV : (1, 5, 4, 4, 0, 0) Destination DV : (3, 3, 2, 2, 2, 2) Subtract : (-2, 2, 2, 2, -2, -2) Discard (-) values: (0, 2, 2, 2, 0, 0) Now we have nodes 41,42 and 52 as each of these neighbors have the same values in the final DV of the result. Out of these approaching, in the similar manner 42 will have the smaller values. So the path 51  42  33 is selected.

HOW TO INTRODUCE ENERGY EFFICIENCY ?  consider the maximum available power at each node which falls in the direction the message should be routed and minimal directional value when picking which node route to take  Instead of simply picking the node with the lowest directional value, the directional value is divided by the power available at that node.  The smaller value of this RATIO power-constrained directional value is the path that is chosen.  ANALYSIS OF POWER USAGE  First, the routing is studied over the diameter of the network and along two possible routes—along the edge and through the interior.  Finally, we simulate DSAP with and without power-aware routing and show the relative performance of each.

Degree of Routing Freedom:  It is the number of alternative paths that a routing protocol can select. It show that as the number of neighbors increases, the degree of routing freedom increases Trade-Off:  There is an fundamental between the number of neighbors and the total power dissipated in the system. HOW DO WE ESTIMATE THE POWER DISSIPATED?  Java simulation program was developed that incorporated the number of nodes, topology, distance, number of bits transmitted, power transmitted / received for each node.  It takes the message, source node and destination node as input and returns the energy dissipated as output.

RESULTS :  For 2D Networks with different number of neighbors the energy consumed is as follows  OBSERVATIONS: edge routing involves less power than interior routing in all cases except for 3 neighbors. Because edge routing must intern fallow interior routing With either routing strategy, as the number of neighbors increases the power dissipated increases for the same number of transmissions.

RESULTS [CONTD.]:  For 3D networks with 1000 nodes and each node having 6 neighbors the energy consumed is as fallows.  Power assessment for 3D network as the number of nodes increased.  OBSERVATIONS : Power dissipated is less when Power-DSAP is used for both the 2D as well as the 3D. The 3D network consumes less power than any of the 2D configurations.

RESULTS [CONTD.]:

CONCLUSIONS:  From this it is clear that path selection affects the amount of power used in the network.  When the power considerations are added to the protocol, we find that the overall power consumption is much more balanced than without taking power into account.  As for now the Power-Aware DSAP is one of the best topology related to wireless sensor networks.

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