Transcript Itai Novitarger & David Haloni ♠ Itai Novitarger & ♠ David Haloni Instructed by : Shay Auster Itai Novitarger & David Haloni Goals 赳  赳 Design & development of.

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♠ Itai Novitarger
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♠ David Haloni
Instructed by : Shay Auster
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Goals
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Design & development of a wireless TDMA
simulation module.
Changing TDMA transmission\reception rates.
Creation of an algorithm performance analysis
platform which includes:
I. Physical & MAC layers.
II. Fragmentation layer – Provides changing rates support.
III. Performance measurement tools.
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OPNET simulation environment acquaintance.
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OPNET Work environment
Powerful network simulation environment.
Allows complex statistics collection.
User friendly GUI.
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Design Work environment
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Lots of Pencils & Papers
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A little about TDMA
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Time Division Multiple Access.
Allows multiple transmitters to access a single
radio-frequency channel without interference.
Allocates separated time slots for each
transmitter.
Incorporates algorithm support for multiple
channel access.
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TDMA Capabilities
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Digital data transmission.
Improved power consumption.
High transmission rates.
Supports real time information transmission
(Audio\Video streaming).
Supports sophisticated QOS Algorithms.
Enable reliable communication between
mobile users.
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Upper Layer
Source
Node Modules
Upper Layer
Sink
Fragmentation
(Transmission)
Fragmentation
(Reception)
Transmission
Queues
Reception
Queue
Physical
& MAC
Layer
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OPNET Node Modules
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Upper Layer Source
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Functions as a node source module.
Generates Data messages:
♠ Poisson generation rate.
♠ Uniform distributed packet size
Upper Layer Sink
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Functions as a destination module in the receiving node.
Gathers & destroys re-assembled messages.
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Fragmentation Layer
Transmission
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Simulates changing transmission rates:
♠ Disassembles large source messages into scaled packets
according to the current transmission rate.
♠ Updates essential packets fields:
♠ External & Internal numbering.
♠ ‘Last’ bit.
♠ Updates relevant statistics.
♠ Inserts packets into transmission queues according to the
current transmission rate.
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Fragmentation Layer
Transmission in OPNET
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Transmission Queues
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A set of passive queues.
One queue per each possible transmission rate.
Each queue is designed to accommodate packets
of a designated size.
Performs as buffers for both Fragmentation & MAC
layers (DownStream).
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Transmission Queues
in OPNET
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MAC & Physical layers (1)
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Transmit packets queued inside the
transmission queues.
Based on TDMA media access control.
Support changing transmission rates:
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Get the packets from the relevant queue
according to the current transmission rate.
Constant transmission time slot.
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MAC & Physical layers (2)
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‘Listen’ to the radio network & capture relevant
packets.
Transfer packets into reception queues.
Update current transmission rate according to an
external file.
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MAC & Physical
layers in OPNET
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Reception Queue
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A single active queue, consists of infinite number
of sub-queues.
Each sub-queue accommodates packets associated
to a specific incoming message.
Fragmentation layer receives sub-queues status
updates when packets arrive from the MAC layer.
Forwards packets accommodated inside a specific
sub-queue, in response to fragmentation layer
request.
Sub-queues are flushed when their TIMEOUT
counter expires.
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Receiver Queue
in OPNET
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Fragmentation Layer
Reception
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Draws all sub-queue packets according to subqueue updates.
Reassembles packets & recreates original source
messages.
Updates relevant statistics.
Sends messages to the sink.
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Fragmentation Layer
Reception in OPNET
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Packet Structure
Source
Dest
Len
Data – (modified length)
External
Internal
ID
chksum
Ack
padding
Last
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Performance Measurement
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Simulation Statistics:
♠ Fragmentation Disassemble Time –
 Based on the average number of packets divided from a
single message, according to the transmitter point of view.
♠ Fragmentation Reassemble Time –
 Based on the average number of packets associated to a
single message, according to the receiver point of view.
♠ Fragmentation Rate –
 Based on the division between the number of messages
which has been splited to those which hasn’t.
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Statistics Results
Disassemble Time
Reassemble Time
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Statistics Results
fragmentation rate
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Future Developments
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Automated Transmission rates algorithm.
♠Currently: rates change according to an input file.
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Finite\Infinite storing queues.
♠Currently: Infinite queues.
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Priority queues.
♠A lot of effort was invested in order to support
convenient future expansions.
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Supplemental Information
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Website:
http://www.Comnet.technion.ac.il/~cn6s02/index.htm
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Questions ???
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