this presentation presents the major issues relative to the WSN. It gives, also, a brief description of the potential solutions

1. 1/24/2014
Networking Issues in
Wireless Sensor
Networks
Presented by:
Souhaiel Ben Tekaya
1

2. Introduction
fields(forest, military, surveillance, transportatio
1/24/2014
• Emerging field in different
n…)
• Role: collect data then transfer it to central
locations.
• Focus on fundamental issues:
• Networking
• Power
2

3. Networking issues
• Limited energy supply,
• limited computing power,
• limited bandwidth of the wireless links connecting data.
1/24/2014
• Differs from classic networks on :
• Routing challenges:
• Data aggregation,
• Coverage/ scalability,
• Data reporting methods (protocols).
3

4. Networking issues
Critical task since we need to consider some factors:
• Node heterogeneity,
• Node failure tolerance,
• Quality of service,
1/24/2014
• Design issues:
 Prevent connectivity degradation by employing energy
management techniques.
4

5. Networking issues (protocols)
• Use position of routers & packet destination to make forwarding
destination.
• Sensitive to rate of change of the network and number of routers
in the network.
• 2 algorithms:
1/24/2014
• Greedy perimeter stateless Routing (GSPR):
• Greedy forwarding: decision made locally (node) based on closest
node to destination.
• Perimeter forwarding: when previous not applicable. Chooses one of
the surrounding nodes based on the right hand rule.
5

6. Networking issues
• Consider energy factor and avoid flooding packets.
1. packet outside region:
1/24/2014
• Geographical and Energy Aware Routing (GEAR)
routing with energy aware metrics (calculate the less
energy consuming way to destination)
2. Packet within region:
restricted flooding algorithm
6

7. Power conservation while
maintaining multi-hop routing
consumer in a sensor.
1/24/2014
• the transceiver is considered the largest energy
• Powering off the sensor will be the best way.
But, areas in the sensor network will be isolated
and inaccessible by queries.
• Most proposed solution: Duty-cycling.
7

8. duty-cycling
Duty-cycling exploit node redundancy in sensor network, by putting
Three categories:
1/24/2014
in a sleep state all unnecessary sensors for connectivity.
Sleep and wake-up: independent from the network topology and
MAC protocol.
low duty cycle combined with MAC protocols: integrated in the
MAC protocol.
duty-cycle control through topology management: Exploiting the
dense aspect of sensor networks.
8

9. Sleep and wake-up

10. a. Sleep and wake-up
independent from the network topology and MAC protocol.
Three categories:
• On-demand: wakeup only when another node wants to talk with it
using two different radios.
• Scheduled rendezvous: closed node are wakeup at exactly the
same time.
• Asynchronous schemes: nodes wakeup independently while always
guaranty an overlapped active period

11. b. low duty cycle combined with
MAC protocols

12. b. low duty cycle combined with
MAC protocols
• TDMA-based: channel access is done on a slot-by-slot
basic, Bluetooth and LEACH are two examples.
• Contention-based: similar to sleep/wakeup scheme, integrating the
sleep/wakeup algorithm to the MAC protocol.
• Hybrid protocols: combines both TDMA and contention protocols.

13. c. duty-cycle control through
topology management
• Exploiting the dense aspect of sensor networks.
• Most common protocols:
a.
GAF: divide the network to fixed square grids.
b.
SPAN: sleep state or to join the backbone upon the connectivity
information given by the routing protocol.
c.
ASCENT: packet loss and connectivity information.