MAC PROTOCOL COMPARISON

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MAC PROTOCOL COMPARISON PERFORMANCE ANALYSIS

• Jian-chuan Lu
• visiting scholar
• DAWN Lab
• EECS of Washington State University
• 2nd November 2000

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Outline of Topics

• TDMA vs. CSMA, simple comparison
• Single station
• delay, throughput and energy consumption
• Interference analysis
• Multi-base-station scenario
• Improved CSMA/CA

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TDMA vs. CSMA

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System parameters

• N number of nodes
  dcross propagation cross distance
  
• D Maximum hop number
  efree free space propagation constant
• Cd average connection degree
  etwo-way ground propagation constant
• Tf data frame time interval
  hr receiver antenna height
• Eelec radio electronics circuit energy(J/bit)
  ht transmitter antenna height
• i data packet length
  islot bit number in one beacon slot
• l packet arrival rate
  g wave length
• d effective transmission distance
  L system signal loss factor
• Nb number of frames between beacon frame

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TDMA SINGLE BASE-STATION

• Average delay (D1)Tf/2
• Channel utilization h(Nb-1)/Nb
• Energy consumption in one super frame
• EmaxNd(ERXETX) islot. ETX(N-1)ERX
• WHERE
• Nd 1/3. Cd .l .Nb. Tf l .Nb. Tf
• ERX i . Eelec
• i . Eelec i efreed2
  when dlt dcross
• ETX
• i . Eelec i etwo-way d4
  when dgt dcross

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CSMA/CA Basic access method
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RTS/CTS 4 way handshake access method

• Channel access using RTS/CTS

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Collision analysis
Basic access methods
RTS/CTS 4 WAY Access methods
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CSMA/CA Performance Analysis

• Basic access method
• Station I transmits to j at time t
• Successful data frame transmission conditions
• No station Aj(dij)-Hj(dij) transmits in the
  time interval(t- b ,t b )
• No station in Ai(dij)-Hi(dij) receives
  successfully a data frame whose transmission was
  initiated in the time interval(t- b ,t b )
• No station in Hij(dij) transmits during the
  interval (t,tl)
• No station in the set Hji(dij) transmits in the
  interval (tlDIFS, tlmaxDIFS, SIFSLack)

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CSMA/CA Performance Analysis

• RTS/CTS 4 way method
• Station I transmits to j at time t
• Successful data frame transmission conditions
• No station Aj(dij)-Hj(dij) transmits in the
  time interval(t- b ,t b )
• No station in Ai(dij)-Hi(dij) receives
  successfully a RTS frame whose transmission was
  initiated in the time interval(t- b ,t b )
• No station in Hij(dij) transmits during the
  interval (t,tLRTS)

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CSMA/CA Performance Analysis From paper
byHarshal S.Chhaya, Sanjay Gupta of Illionis
Institute of Technology

• Notation
• A the area covered by a mobile station
• Ai(d) the circular area of radius d around
  station I
• Xi location of station I
• dij distance between station I and j
• dij a .dij , a gt1 Denote the capture range
  of station j
• a capture parameter and is a function of the
  receiver characteristics and signaling format
  used
• Hj(d) the set of stations that are hidden from
  station j and are in circle of radius d around it
• Hij(d) the set of stations that are hidden from
  station I but not from station j in a circle of
  radius d around station j
• L length of a data frame
• Ltype length of a type frame
• b propagation delay normalized by the expected
  length of a data frame, include the carrier
  sensing delay
• G(I,j) exponentially data packet arrival rate
  generated at station I that is destined to j
• Pc the probability that no exchange of RTS/CTS
  frame is successful in a given renewal interval

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CSMA/CA Performance Analysis

• Assumptions
• .ignore the effect of frames error due to bit
  error introduced by channel noise
• .limited station mobility
• .all data frame are of identical size
• . The transmission from any station that are
  destined for distinct destinations are
  independent
• Definitions
• Renewal point the instance of the completion of
  a successful transmissions and/or a collision
• Throughput defined as the number of
  successful transmissions between successive
  renewal points, divided
• by the length of
  the time interval between the renewal points
• Ts the expected length of time interval
  between successive observations of the channel
  being idle more than DIFS, when in the
  intervening renewal interval at least one
  successful transmission occur
• Tc the expected length of time interval
  between successive observations of the channel
  being idle more than DIFS, when in the
  intervening renewal interval only collision(s)
  occur
• Tcgt 1/GLDIFS b
• Ts 1/GLSIFSLackDIFS b
• Ps(I,jm,n), m,n e A, the probability that the
  transmission of a data frame from station I to j
  is successful given that the transmission of a
  data frame from station m to n terminated the
  idle period, ie. Was the first data frame to be
  transmitted once the channel had been sensed idle
  for time greater than DIFS
• C(I,j) the set at all transmitter-receiver
  station pairs(m,n) such that m e
  Aj(dij)-Hj(dij) or n e Ai(dij)-Hi(dij)

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throughput
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Interference analysis
Local connectivity view

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Hybrid multi-base-station architecture
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Involved problems

• Hybrid station type, flat architecture, multi hop
  ad hoc wireless network. No whole range central
  control available. Different with existing
  cellular and pure ad hoc wireless network
• End to end multi-mode communication support
  B-B,B-S,S-S
• Sensor node energy limitation
• Multi-hop ad hoc wireless sensor network route,
  MAC protocols, esp. network self-organization,
  topology finding and adaptation, collision free
  MAC protocols. Hidden terminals and efficient
  controlled broadcast problems
• Base-station random access and mobility support
• Network delay and throughput optimization.

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Hybrid type station , hybrid protocol
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Improve CSMA/CA

• CSMA/CA with priorities

Elimination of random bursts
Each high priority node transmits a burst for a
geometrically distributed number of slots and
listens for one slot, if another burst is heard,
the node stops contending for the channel
The surviving nodes defer transmission for a
geometrically distributed number of slots while
listens to the channel,,if any channel activities
is detected,the packet transmission is postponed.
Listen after burst
0 1 2 3 4
DATA
DATA
ACK
ELIMINATION
YIELD
Nodes having a packet with priority p transmit a
burst in slot p1 , if no higher priority burst
has been heard
PRIORITIZATION Listen for priorities 0,1,2,3,or
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This MAC protocol used in HIPERLAN I standard
Operation of the MAC protocol supporting
prioritization and random burst elimination
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Our proposeself-organization,MAC and route
protocol Synchronized sensor network frame and
slot structure
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Our proposeself-organization,MAC and route
protocol architecturesingle base-station