1. Simulation of Resources allocations for heterogeneous IP networks
Tutor : Dr. Yehuda Ben-shimol
Presented by : Sharon Sason
Ayelet Eshel

2. Projects motivation

3. LSRT – large scale rural telephony
The Challenge:
Delivering the power of
telecommunication to the
remote regions of the globe.
Providing access to reliable
,low cost telephone and
data services.

4. The Answer – heterogenic Network
HUB-Composed of a very large -15 to 36-foot (4,5 -11m)- antenna. The HUB controls and manages the network.
The Topology (star configuration)
VSAT- very small aperture terminal
VSAT - Very Small Aperture Terminal
VSAT products provide networking and telephony between a central HUB and tens to thousands of locations across wide geographical areas without the need for terrestrial infrastructure.
HUB –
Composed of a very large -15 to 36-foot (4,5 -11m)- antenna. The HUB controls and manages the network , The HUB is capable for receiving low power beams , and amplify them to transmits high power beams.

5. Multiple access to the satellite network
Uplink – The Bandwidth allocated for the access from the VSATs to the HUB.
Downlink – The Bandwidth allocated for the access from the HUB to the VSATs.
Multiple VSATs compete on the uplink resource while only the HUB use the downlink , so the multiple access problem refers only to the uplink.
The solution must take under consideration the special characteristics of the satellite network.

6. Satellite network special characteristics
Delay – Long distances creates
large delay (270 msec).
Packet loss – heavy packet loss due to atmospheric conditions.

7. Solution :
FTDMA protocol

8. FTDMA – Frequency and Time Division Multiple Access.
This protocol is a
Combination of
FDMA and
TDMA ,in order
To Reduce
collisions.
Time
Time slot 3
Time slot 2
Time slot 1
Channel 0
Channel 1
Channel 2
Frequency

9. FTDMA – RA/DA Two operation modes implement the protocol.
RA – Random Access : a station randomly selects a frequency channel, and transmit in the beginning of a time slot (slotted aloha). There is a low probability for collisions.
2) DA - Dedicated Access : a station receives specific allocations of time and frequency channel , and transmit accordingly. The probability for collisions is zero.
There are separated frequency zones for RA and for DA

10. Real time/Non real time - applications
Non real time applications (http/FTP/ ) - will be sent in RA mode.
Real time applications (voice/video) – requests for time and frequency allocations will be sent in RA. When the request is granted the session will continue in DA mode using the allocated resources.

11. FTDMA – for real time applications
1. VSAT sends request to the HUB in RA mode.
2. HUB - responds by allocating resources and send them to the VSAT.
3. The source sends data
to the destination in DA mode.
HUB
4. VSAT sends a close session signal to the HUB which release resources.

12. Implementation Tool

13. OPNET network technology development environment
Hierarchical Network Modeling
Object-oriented Modeling
Finite State Machine Modeling
Highly Efficient Simulation Engine
Comprehensive Model Library
Integrated Analysis, Animation, and Debugging Tools

14. OPNET Main Editors
Network Editor
Process Editor
Node Editor

15. Our Model
Indoor
outdoor
HUB

16. Indoor/outdoor node model

17. Our Outdoor Mac Layer – Process model
Transmit the packets of this session in DA mode (every begging of its time slot
Waiting for something to happen
Receiving the first packet of the session, schedule an event for allocation request
Receive allocation packet from the physical layer of the satellite network and register the session as DA with the given allocations
Sending request to the hub in RA mode

18. Outdoor – Real time sessions management
Time slot 3
Time slot 2
Time slot 1
Channel 0
Channel 1
Channel 2
DA Frequency's
IP source
IP destination
IP source
IP destination
sessions

19. HUB – allocation table Time DA Frequency's Outdoor 0 Outdoor 1
Time slot 0
Time slot 1
Time slot 2
Channel 0
Session 1
Session 2
DA Frequency's
Channel 1
Session 6
Session 2
Session 4
Channel 2
Session 5
Session 3
Session 7
Outdoor 0
Outdoor 1
Outdoor 2

20. Next Stage …

21. Analyses Collecting network performance statistics
and analyzing the results

22. The END