Present :Daniel Hochberger

1
Wireless Protocol performance
Mid-presentation

• Present Daniel Hochberger
• Yonatan Keller
• Supervisor Shai auster

2
Project goals

• Working over a TDMA wireless and clean network .
• Design of layer algorithm upon a changing
  transmission rates network.
• Optimize the network by
• Developing a MAC layer protocol to unify/separate
  packets.
• Implementing an acknowledgment mechanism over the
  network.
• Collect statistics and analyze algorithm
  performances.
• Learn OPNET simulation environment.

3

• Clear and simple modeling paradigm
• Object-oriented modeling
• Library of detailed protocol and application
  models
• Highly efficient simulation engine
• Many integrated tools to display simulation
  results

4
About TDMATime Division Multiple Access

• Digital transmission technology.
• Allocates unique time slots to each user within
  each channel.
• Allows a number of users to access a single
  radio-frequency channel.
• No interference of simultaneous transmissions.
• Provides the user with extended battery life and
  talk time.
• Adapted to the transmission of voice
  communication data carry rates of 64 kbps to 120
  mbps.

5
Layers diagram
Ack source
Data source
Packet storing queues
Unifying layer
MAC/physical layer
6
Packet storing queues

• Transmitter queue Vs Receiver queue
• M/M/1 queues
• Different queues for different transmission rates
• Contains both data and acknowledgment packets

7
Unifying packets motivation

• Increase network performances
• Reduce bit transmission by unifying headers.
• Lower number of transmitted packets.
• Optimize the throughput of the channel.
• Maximal exploitation of the time-slot allowed.
• Adapt the protocol to changing transmission rates
  network.

8
Unify/separate packets
9
Unifying process features

• Dual nodes
• M/M/1 queue at each node
• Different sizes of packets
• Need for an agreed unified-packet format.
• Assumptions
• The queue is supposed to be never empty (not
  waiting for other packets to arrive)
• The size of the packets is less than the optimal
  packet size
• The changing transmission rate is given
  (non-online)

10
Packet format
Data packet format
Ack
DATA
SN
RN
Size
Ack packet format
RN
Ack
Unified packet format
Packets
Packet1
Packet2
PacketN
11
Acking mechanism

• Implemented as piggy-backing
• 3 main ARQ protocols
• Stopwait
• Go-back-N
• Selective Repeat
• Issues
• Acknowledgment packet can be unified with others
• Need for a timing protocol based upon TDMA

12
Performance measurement

• Message transmission rapidity
• t t packet transmission t packet creation
• Network general efficiency t t ack reception
  t packet creation
• Channel throughput
• SW
• GbN
• SR

13
THE END