Elective Participation in Ad Hoc Networks Based on Energy Consumption

1
Elective Participation in Ad Hoc Networks Based
on Energy Consumption

• Marc R. Pearlman, Jing Deng, Ben Liang, and
  Zygmunt J. Haas
• School of Electrical and Computer Engineering,
  Cornell University
• Proceedings of IEEE Global Telecommunications
• Conference (Globecom), 2002

2
Introduction 1/3

• Ad hoc network nodes
• Typically portable and thus powered by limited
  capacity batteries
• Researches on energy conservation
• Minimum energy routing
• Singh98, Rodolplu99, Michail00, Gomez01, Chang00
• Optimal transmission radius for minimal interface
  and energy consumption
• Bononi99, Rodoplu99, Sanchez99, Wattenhofer01
• Ad hoc nodes active period reduction
• Chen01, Xu01

3
Introduction 2/3

• Radio transceiver in various states Stemm97

4
Introduction 3/3

• Best policy to maximize battery life
• To leave nodes in SLEEP mode or disconnect them
  altogether
• But conflict with the welfare of the whole
  network
• Energy Dependent Participation (EDP) scheme
• Gradually reduces a nodes participation in the
  network as batterys energy in consumed
• Maintaining active network applications
  connection
• Avoiding network partitioning

5
Energy Dependent Participation (EDP) 1/4

• Network participation depend on nodes remaining
  energy level

B
Battery Life
A
75
50
25
0
C
Network Participation Rate
E
D
lt Ad Hoc Network gt
6
Energy Dependent Participation (EDP) 2/4

• Two-state model for EDP
• E(t) amount of energy stored in a node at time
  t

E(t)/E(0)
SLEEP
ACTIVE
E(t)/E(0)
1 - E(t)/E(0)
1 - E(t)/E(0)
7
Energy Dependent Participation (EDP) 3/4

• Periodic examination of energy level
• ACTIVE for the next t seconds with probability
  E(t)/E(0)
• SLEEP for the next t seconds with probability 1
  E(t)/E(0)

decision for next t
ACTIVE
SLEEP
0
t
2t
3t
4t
5t
6t
7t
8t
8
Energy Dependent Participation (EDP) 4/4

• Granularity of time interval t
• Extremely large
• draining its battery too quickly
• Short interval
• More frequent transitions between ACTIVE and
  SLEEP modes
• Bogging down the network with control traffic
  (e.g., routing protocol updates) and depleting
  energy supply

9
Maintaining Network Connectivity 1/2

• Transition into SLEEP mode can cause
• Disconnection of own active networking
  application
• Further network partitioning
• A radio transceiver can override a transition
  into sleep mode in these cases
• To maintain network connectivity
• Distinguishing active data session
• Recently originated or delivered network layer
  packets
• Avoiding network partitioning
• To compute overall network connectivity
• Link state information amassed by routing protocol

10
Maintaining Network Connectivity 2/2

• Three-state model for EDP with partition checking
• WAKE-UP state up-to-date view of network topology

E(t)/E(0)
SLEEP
ACTIVE
E(t)/E(0)
1 - E(t)/E(0)
1 - E(t)/E(0) and not partitioning
1
E(t)/E(0) or partitioning
WAKE-UP
11
Partition Checking Algorithm 1/4

• How to find the network partitioning due to a
  node withdrawal

E
SLEEP
B
SLEEP
A
D
F
C
Articulation Point
lt Graph Representation of Ad Hoc Network gt
12
Partition Checking Algorithm 2/4

• Straightforward approach
• Twice evaluates the connectivity between all node
  pairs
• First for a current network and then for a
  network without a node
• All-pairs shortest paths algorithms
• Floyd-Warshall O(N3)
• Johnson O(N2logN N2k)

13
Partition Checking Algorithm 3/4

• Computationally less complex algorithm
• All incoming neighbors of node X can reach all
  outgoing neighbors of X without passing through X

Incoming neighbors
Ni
X
Nj
Outgoing neighbors
14
Partition Checking Algorithm 4/4

• Assumption
• N nodes in the network, each of which has an
  average of k neighbors
• Algorithm
• Constructing an adjacency-list of network graph
• Traversing the graph from incoming neighbors of
  X, at each hop verifying whether an outgoing
  neighbor of X has been visited
• O(NlogN Nk2) or
• O(NlogN Nk) in
  bi-directional link

15
EDP with Zone Routing Protocol 1/3

• Zone Routing Protocol (ZRP)
• Hybrid routing protocol
• Proactive within routing zone and reactive
  without routing zone

D
S
Routing Zone Radius
16
EDP with Zone Routing Protocol 2/3

• Complexity of EDP partition checking with ZRP
• Relatively Small connectivity information
• Current local routing zone connectivity
  (proactive)
• Snapshots of some distant network paths
  (reactive)
• Unnecessarily remaining active mode
• But preventing partitioning as long as the
  available network information is valid

17
EDP with Zone Routing Protocol 3/3

• Problems of EDP with other routing protocols
• Proactive routing protocol
• Sleeping and waking-up can potentially incur more
  link updating traffic
• Reactive routing protocol
• Leads to more route querying traffic when
  established routes break due to intermediate
  nodes entering the sleep mode

18
Evaluations 1/6

• Simulation model (1/2)
• Uniform random distribution of 200 stationary
  nodes
• 2 x 2 kilometer in ad hoc network area
• Each node has 8.4 x 103 joules of two fresh AAA
  batteries
• Orinoco 802.11b PC Card
• 11Mbps and effective transmission radius of 250
  meters

19
Evaluations 2/6

• Simulation model (2/2)
• Zone Routing Protocol with zone radius of 3
• Link-state update period is 10 seconds
• Every 50 seconds, 20 independent data sessions
• Randomly chosen source-destination node pairs
• End-to-end bit rate 1.1Mbps

20
Evaluations 3/6

• Performance of EDP without Partition Checking
  (1/2)

21
Evaluations 4/6

• Performance of EDP without Partition Checking
  (2/2)

22
Evaluations 5/6

• Performance of EDP with Partition Checking (1/2)

23
Evaluations 6/6

• Performance of EDP with Partition Checking (2/2)

24
Related Works

• Span Chen01
• Set of coordinators to forward data packets
• Clock synchronization by sending and receiving
  beacons
• Geography-informed energy conservation Xu01
• Periodical determination of the number of nearby
  nodes within a pre-defined grid
• Equipped with GPS

25
Conclusion

• Energy Dependent Participation (EDP) scheme
• Distributed and independent energy conserving
  scheme
• Battery lifetime increment due to reduction of
  the amount of time that the transceiver are
  active
• Sleep mode with probability proportional to the
  amount of consumed energy
• Network connectivity improvement with partition
  checking

26
Partition Checking Algorithm ext.
Directed Graph
Adjacency List
B
A
B, C
A
C
B
C