Energy Efficient MAC Protocols For Ad Hoc Networks

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Energy Efficient MAC Protocols For Ad Hoc
Networks

• by
• Vanitha SivaSubramaniam
• Distributed System Design Professor Dr. Wu
  Jie
• 4/10/2003

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OUTLINE

• Ad Hoc Networks
• Power Consumption
• Solutions For Power Limited Devices
• Energy Efficient MAC Protocols
• Conclusion

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AD HOC NETWORKS

• Wireless terminals communicating with one another
  with no pre-existing infrastructure in place
• Infrastructure-less network

• Application
• Conferencing
• Home networking
• emergency services
• sensor networks

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Ad Hoc Network
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Problems in Ad Hoc Wireless Networks

• Hidden Terminal
• Exposed Terminal
• Energy of individual node and of the network as a
  whole
• Mobility

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Power Usage in Different Modes
Model Transmit Receive Standby
GEC Plessey DE6003 2.4 GHz 1.8 W 0.6 W 0.05 W
Lucents 15 dBm 2.4 GHz Wavelan radio 1.75 W 1.475W 0.08 W
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Power Consumption in Ad Hoc Networks

• Wireless hosts are powered by batteries which
  provide a limited amount of energy
• Third Generation wireless networks carry diverse
  multimedia traffic Data, voice and video

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Solutions for Power Limited Devices

• Low power system design focus on power usage in
  CPU, transmitter and receiver embedded in
  portable devices
• Network protocols are designed for energy
  efficiency
• Recent research has been devoted to low-power
  wireless access protocols like the MAC(Medium
  Access Protocols)

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Protocol Stack of a Wireless System
Application Services
OS Middleware
Network
Data Link
Physical
MAC Protocol
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Functions of Data Link layer

• Responsible for wireless link error control
• Security (Encryption and Decryption)
• Mapping network layer packets into frames
• Transmission and reception of frames over the air

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Principles to Conserve Energy at DATA Link (MAC)
Level

• Collision Avoidance
• Energy Conservation
• Power saving in different mode
• Switching between modes

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Medium Access Control Protocol
The MAC protocol simply determines when a node is
allowed to transmit its packets and typically
controls all access to the physical layer MAC
protocol is responsible for allocating the time
frequency space among the mobiles sharing the
wireless channel
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DATA Communication in AD Hoc Networks
NODE A Transmitting DATA to NODE B
NODE B (Receiver)
RTS
1
CTS
2
DATA
ACK
4
3
RTS- Request To Send CTS-Clear To
Send ACK-Acknowledge
NODE A (Sender)
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Energy Efficient MAC Protocols

• MACA Protocols
• MACA ( Multiple Access with Collision Avoidance)
• MACA-BI( By Invitation)
• CSMA Protocols
• DFWMAC (Distributed Foundation Wireless MAC)
• EY-NPMA (Elimination Yield Non-Preemptive
  priority Multiple Access)
• DBTMA ( Dual Busy Tone Multiple Access)

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Continue..

• Power Conserving MAC Protocols
• MARCH (Media Access with Reduced handshake)
• PAMAS (PowerAware Multi-Access Protocol with
  Signaling)
• Power Control MAC Protocols
• PCM ( Power Control MAC)

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Multiple Access with Collision Avoidance (MACA)

• Three way handshake, RTS-CTS-DATA
• Power control feature Inhibits a transmitter
  when a CTS packet is overheard to limit power
• Less DATA packet collisions
• Resolve the hidden terminal and exposed node
  problem

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Handshake in MACA
NODE A (Sender)
DATA
RTS
CTS
NODE B (Receiver)
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MACA-BI( By Invitation)

• Two way handshake. RTR (Ready To Receive)-DATA
• Receiver sends invitation to the sender
• Reduces transmit/receive turn around time ( ie.,
  up to 25 microseconds)
• Less control packet collisions compared to MACA

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Handshake in MACA-BI
NODE A (Sender)
DATA
RTR
NODE B (Receiver)
RTR- Ready To Receive
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DFWMAC ( Distributed Foundation Wireless MAC)

• Four way handshake RTS-CTS-DATA-ACK
• A sender node waits for DIFS( Distributed
  Inter-Frame Space) before making an RTS attempt
• A node enters a SIFS ( Short Inter Frame Space)
  before sending an ACK frame, DATA and CTS
• NAC (Network Allocation Vector) indicates the
  duration of the current transmission

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Four Way Handshaking in DFWMAC
SIFS
DIFS
RTS
DATA
Sender node
SIFS
SIFS
CTS
ACK
Receiver node
NAV(DATA)
NAV(CTS)
NAV(RTS)
Others
NAV- Network Allocation Vector
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EY-NPMA (Elimination Yield-Non- Preemptive
Priority Multiple Access)

• The node senses the medium and starts
  transmitting if it finds the channel idle
• Channel busy The channel access has three Phases
• Prioritization Phase Priority is decided
• Contention Phase Nodes of same priority contend
  and one station wins
• Elimination Phase
• Yield Phase
• Transmission Phase DATA transmission

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DBTMA (Dual Busy Tone Multiple Access)

• Two channels
• Data Channel- Data packets
• Control Channel- RTS and CTS
• Two out-of-band busy tones
• Receive busy tone
• Transmit busy tone
• Resolve Hidden terminal problem

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Handshake in DBTMA
NODE A (Sender)
DATA
Transmit Busy Tone
RTS
Receive Busy Tone
CTS
NODE B (Receiver)
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MARCH (Media Access with Reduced Handshake)

• Less number of handshakes Reduces the control
  overhead by reducing the number of RTSs along
  the multi-hop path
• Exploits overhearing by using omni directional
  antenna

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Handshake Mechanism in MARCH
A
B
C
D
RTS1
CTS1
CTS1
DATA
CTS2
CTS2
DATA
DATA
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PAMAS ( Power Aware Multi-Access Protocol with
Signaling)

• Separate signal channel
• Conserves battery power Power off nodes not
  transmitting or receiving
• Wait-for CTS state
• After a node sends RTS
• Await DATA state
• After a node sends a CTS
• Transmit DATA state
• After a node gets a CTS
• Binary Exponential Backoff (BEB) Doubling wait
  time in sender node

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Power Control MAC Protocol

• Power Control MAC (PCM)
• PCM periodically increases the transmit power to
  max. power during the DATA packet transmission
• PCM achieves throughput comparable to IEEE 802.11
  with less energy

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Transmission Range, Carrier Sensing Zone and
Carrier Sensing Range
Carrier Sensing Zone
Transmission Range
A
C
B
D
E
Carrier Sensing Range
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Power Control MAC (PCM)

• Source and destination transmit the RTS and CTS
  using max. power.
• Source transmit DATA using a lower power level
• Source node periodically transmits DATA at max.
  power, to avoid collision
• Destination transmits ACK using minimum power
  required to reach the source node

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DATA Transmission -Power Control MAC Protocol
CTS
DATA
RTS
B
C
D
A
ACK
A
B
Sender Node
Receiver Node
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CONCLUSION

• Of the many protocols existing only few of them
  focus on the conservation of battery power
• MACA Vs MACA-BI MACA-BI reduces transmit/receive
  turn around time, hence saves power while
  changing the mode
• MACA-BI has less control packet collisions
  compared to MACA
• In CBR ( Constant Bit Rate) traffic MACA-BI has
  high efficiency, but in bursty traffic
  performance degrades compared to MACA

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Continue

• DFWMAC Vs EY-NPMA DFWMAC has more throughput
  than EY-NPMA 2
• PAMAS Power saving range 10-50
• 4 without affecting delay or throughput
• PCM Power Control MAC requires a frequent
  increase and decrease in transmit power, hence
  implementation difficult 3

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References

• Ad Hoc Mobile Wireless Networks Protocols and
  Systems, C-K Toh.
• Ajay Chandra V.Gummalla and John O. Limb, Georgia
  Institute of Technology, Wireless Medium Access
  Control Protocol, IEEE communications Survey,
  2000.
• Eun-Sun Jung and Nitin H. Vaidya, A Power
  Control MAC Protocol for Ad Hoc Networks,
  MOBICOM02, September 23 28, 2002.
• Suresh Singh and C.S.Raghavendra, PAMAS-Power
  Aware Multi-Access Protocol With Signalling for
  Ad hoc networks, in ACM Computer Communications
  Review, July 1998.
• C-K. Toh, Vasos Vassiliou, Guillermo Guichal and
  C-H. Shih,March A Medium Access Control
  Protocol for Multihop Wireless Ad Hoc Networks,
  Proceedings of IEEE Military Communications
  Conference( MILCOM), Los Angeles,2000.

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Continue

1. Fabrizio Talucci and Mario Gerla, MACA-BI(MACA
   By Invitation) A Wireless MAC Protocol for High
   Speed Ad Hoc Networking, Proc. IEEE ICUPC
   97,1997
2. Kyu-Tae Jin and Dong-Ho Cho, Optimal Threshhold
   Energy level of Energy Efficient MAC for
   Energy-limited Ad-hoc Networks, IEEE 2001.
3. Jyh-Cheng Chen, Krishna m. Sivalingam, Prathima
   Agarwal, and Shalinee kishore, A Comparison of
   MAC Protocols for Wireless Local Networks Based
   on Battery Power Consumption, IEEE INFOCOM, Mar.
   1998.
4. J. Weinmiller et al., Performance Study of
   Access Control in Wireless LANs IEEE 802.11
   DFWMAC and ETSI RES 10 HIPERLAN, Mobile Networks
   and Application,vol. 2, no1, 1997, pp 55-67.

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