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Propagation Delay and Receiver Collision Analysis in WDMA Protocols

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on Communication Systems, Networks and Digital Signal ... transmits the control packet according to Slotted Aloha protocol: control channel collisions ... – PowerPoint PPT presentation

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Title: Propagation Delay and Receiver Collision Analysis in WDMA Protocols


1
Propagation Delay and Receiver Collision Analysis
in WDMA Protocols
School of Electrical and Computer Engineering,
National Technical University of Athens,
Greece, e-mail ipount_at_cs.ntua.gr
  • I.E. Pountourakis, P.A. Baziana and G.
    Panagiotopoulos

5th Int. Con. on Communication Systems, Networks
and Digital Signal Processing CSNDSP 2006 July
19-21, 2006
2
We present
  • A network protocol
  • for Wavelength Division Multiple Access (WDMA)
  • for synchronous transmission
  • in passive star topology
  • with multiple control channels Multi-channel
    Control Architecture (MCA)
  • We achieve performance improvement exploiting
  • MCA less processing overhead for control
    information
  • propagation delay latency simple MAC protocol to
    avoid data channel conflicts
  • Analysis
  • discrete time Markovian model
  • for finite number of stations and WDM channels
  • with receiver collision effect

CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
3
WDMA Protocols
  • Performance parameters
  • control channel collisions
  • data channel collisions
  • receiver collisions
  • propagation delay
  • Single common-shared control channel vs MCA
  • Single control channel
  • stations can not receive and process all control
    packets
  • maximum processing rate is limited to the speed
    of electronic interface
  • MCA
  • multiple control channels to exchange control
    information
  • elimination of electronic processing bottleneck
  • MAC techniques to avoid of data channel
    collisions
  • Normalized propagation delay R
  • is the ratio of propagation delay to data packet
    transmission time L
  • has large values in WDM networks
  • is a useful attribute to develop WDMA algorithms

CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
4
Passive star multi-wavelength architecture
  • Network model
  • M number of stations
  • v - number of control channels (?c1,..,?cv )
  • N - number of data channels (?d1,..,?dN)
  • Each station has
  • a tunable transmitter tuned at all channels
    ?c1,..,?cv,?d1,..,?dN
  • v fixed tuned receivers one for each control
    channel
  • a tunable receiver for data channels ?d1 ,..,?dN
  • Time reference
  • common clock to all stations
  • cycle C1(R1)L time units

CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
5
Packet Transmission Access Mode (1)
  • Packet generation
  • independently at each station
  • following geometric distribution
  • free stations probability p
  • backlogged stations probability p1
  • The station attempting to transmit
  • chooses randomly a wavelength for data packet
    transmission
  • informs the other stations by sending a control
    packet
  • chooses randomly one of the v control channels
  • transmits the control packet according to Slotted
    Aloha protocol control channel collisions
  • monitors the MCA with its fixed tuned receivers
  • (RL) time units later knows the data channel
    transmission claims of all stations

CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
6
Packet Transmission Access Mode (2)
  • Cases
  • if control channel collision the station becomes
    backlogged
  • if no control channel collision
  • if the selected data channel is chosen from some
    other station
  • data channel collision avoidance algorithm is
    applied
  • only one among the competed stations transmits
  • the others stations become backlogged

CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
7
Packet Transmission Reception Mode
  • The destination station
  • waits RL time units after data packet
    transmission
  • adjusts its tunable receiver to the data channel
    for reception
  • Receiver collisions
  • if two or more packets are addressed to the same
    destination
  • one of them is correctly received
  • the others are aborted
  • Free stations become backlogged in case of
  • control channel collision
  • data channel collision
  • receiver collision at destination

CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
8
Model analysis
  • Performance is described by a discrete time
    Markov chain
  • Markov system state Xt
  • is the number of busy stations in each cycle
  • computes
  • the one step transition probabilities
  • the steady state probabilities
  • performance measures in steady state
  • throughput Src
  • number of backlogged stations B
  • input rate Sin
  • delay D

CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
9
One step transition probabilities Pij(Xt1j
Xti)
Case D if ji then Pij
Case A if jlti-N then Pij0
Case B if j i-N
then Pij
Case E if jgti then Pij
Case C if i-Nltjlti then Pij
CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
10
Performance Measures (1)
  • Steady state probabilities by solving the system
    of the linear equations
  • p p P
  • P transition matrix with elements the
    probabilities Pij
  • p row vector with elements the steady state
    probabilities pi
  • Conditional throughput Src(i) the expected value
    of the output rate, Src(i)EAt Xti

where
CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
11
Performance Measures (2)
  • Steady state average throughput Src
  • Steady state number of backlogged stations B
  • Conditional input rate Sin(i) the expected
    number of arrivals
  • Steady state average input rate Sin
  • Throughput per data channel Sd
  • Delay D the average cycles that a packet has
    to wait until its transmission

CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
12
Throughput per data channel Sd dependence on N
  • As N increases for fixed stations
  • probability of data packet successful
    transmission increases
  • probability of data packet rejection at
    destination increases
  • Throughput per data channel Sd decreases

CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
13
Rejection probability dependence on N
  • As N increases for fixed stations
  • probability of data packet successful
    transmission increases
  • probability of data packet rejection at
    destination increases

CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
14
Throughput per data channel Sd dependence on R
  • As R increases
  • C increases increasing function of R
  • Sd decreases inverse proportional function of C
  • cycle percentage for successful transmission
    decreases
  • essential reduction of Sd

CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
15
Delay D vs Throughput per data channel Sd
dependence on R
  • As R increases
  • significant increase of D
  • performance deterioration
  • strong dependence of both Sd and D from R

CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
16
Results
  • System efficiency in WDMA depends on
  • powerful influence of R
  • key role of receiver collisions (correlation of
    v, N, M)
  • Both R and receiver collisions
  • sought be taken into consideration
  • Our motivation
  • exploitation of R
  • introduction of access algorithm to avoid data
    channel collisions
  • use of MCA to minimize headers processing
    requirements
  • improvement of system performance

CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
17
  • Thank you for your attention
  • Questions

CSNDSP 2006
I.E. Pountourakis, P.A. Baziana and G.
Panagiotopoulos
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