1. By:
PRAJWAL PANCHMAHALKAR
NISHANTH REDDY KOMMIDI

2.  Wireless Sensor Network (WSN) consists of spatially distributed
autonomous sensors which cooperatively pass their data through the
network to a main location
 This work is motivated by SPMS (Shortest Path Minded SPIN) protocol

3.  Although SPMS was successful in achieving better latency
and low power consumption compared to the SPIN protocol, it
lacks in the following areas:
 Energy at the nodes is not considered:
 Relay nodes have additional overhead as they have to relay the
data between source and destination
 If a node in shortest path fails and the SCONE is not in the
range of the node sending the request then there is no solution
provided.
◦ But the aim of SPMS was fault tolerance !

4.  We assume that the communication overhead is higher than the storage
overhead

5.  We discuss the failure cases of SPMS to provide a solution for the SPMS
protocol
 Here each node has the information of its neighbors zone along with its
own zone
 A Node also maintains the routing table to each of its neighbors.
 Motivated from SPIN and SPMS protocols

6. C
E
D A B
F Routing Table of
Neighbor B
Routing Table of A E
Destination Cost Via F
B 1 -
A
C 1 -
D 2 C

7.  Relay nodes (we call smart relay) are aware of its own residual energy and
the energy it can spend the current communication
 Smart relays, when they get a REQ from a destination node estimates the
cost in relaying the data and calculates the Energy,
 Er = Ep – (Erec + Et)
 Where,
 Er = Energy expected to remain after relaying
 Ep = Energy present at current time
 Erec = Energy spent in receiving the data from the source
 Et = Energy spent in transmitting the data to the destination

8.  Relay nodes then set a 3 energy bits in it’s REQ while sending to the
secondary relay node. We call it En-bit
 This bit is a product which has the information of how much battery energy
will be left in the relay node after the relay of data along with the cost.
 The secondary relay node based on the En-bit will go into a waiting state
which will be inversely proportional to En-bit
 Trw α 1/En –bit
◦ Trw - Waiting time for the smart relay node.
 Meanwhile the nodes present in the zone of the relay node which over
hears the REQ also analyze the En-bit and calculate their own En-bit if
they have both the destination and secondary relay node in their routing
table and sends to secondary relay node

9. E
B C
A D
F
source
destination
Relay nodes
Nodes in zone of relay nodes

10. E
REQ
B C
A F D
Node C calculates the energy it will be left with after
the relaying
source
destination
Relay nodes
Nodes in zone of relay nodes

11. E
overhear
REQ
B C
overhear
A F D
source
destination
Relay nodes REQ – Contains En-Bit
Nodes in zone of relay nodes

12. E
Trw Calculate En-bit and is it
Are B and D in my zone ?
higher than C ?
B C
A F D
source
destination
Relay nodes
Nodes in zone of relay nodes

13. F – has High En-bit
E
B C
A F D
source
destination
Relay nodes
Nodes in zone of relay nodes

14. F – has High En-bit
E
SNIP
B C
DAT
A F D
source
destination
Relay nodes
Nodes in zone of relay nodes

15. E Works similar to energy
aware case where nodes
in the zone of C – E and F
take up
B C
A D
F
source
destination
Relay nodes
Nodes in zone of relay nodes