Orthogonal Routing Protocol

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Orthogonal Routing Protocol

• Bow-Nan Cheng

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ORP Overview

• Introduction / Basic Principles
• Design Goals
• Key Assumptions
• Key Advantages/Benefits of ORP
• ORP Technical Specifications
• Key Obstacles to Overcome
• Simulation Parameters
• Simulation Results (Todo)

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Introduction

• Orthogonal Routing Protocol (ORP) is a
  lightweight, stateless, and distributed routing
  protocol based on rendezvous point abstractions.
  It is designed to provide connectivity under
  extreme conditions of high-speed mobility, sparse
  node environments, connectivity disruptions and
  minimal information due to lack of global
  positioning systems (ie GPS), neighbor states,
  among others.

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ORP Basic Concepts

• FSO transmissions are directional by nature with
  minimal beam-width
• Drawing two pairs of perpendicular lines
  intersecting at two different nodes will always
  yield atleast 1 intersection in each direction
  between the perpendicular line pairs (see
  picture)

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ORP Basic Concepts

• In many cases, nodes will have different sense of
  direction (ie Node D thinks north is to the
  right while Node A thinks north is up)
• Orthogonal intersections will yield a rendezvous
  point/node regardless of individual nodes sense
  of direction
• Supposing Node A wishes to send to Node D, the
  path taken would be through the
  intersection/rendezvous node as show in picture

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ORP Design Goals

• Provide Connectivity Under Extreme Conditions and
  with Minimal Information
• Extreme Conditions
• High Speed Mobility
• Sparse Networks
• RF Connectivity Disruptions (ie Jamming etc.)
• Minimal Information
• Lack of global positioning system (ie GPS)
• Lack of localization systems (GLS, Landmark etc.)
• No link state information
• No ability for basic neighbor discovery

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Key Assumptions / Definitions

• Directional FSO Transceivers
• tessellated to simulate
• omni-directional ability
• if all transmitting/receiving
• at the same time
• Node Local Sense of Direction
• 2-D Flat Plane Topology (future work to include
  3-D)
• Def ORP Broadcast A node sending information
  through 4 orthogonal transceivers only

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ORP Key Advantages

• Connectivity Under Extreme Conditions
• Efficient Medium Usage (FSO Property)
• Increased Security (FSO Property)
• True Stateless Nature
• Minimal Information Needed for Successful Routing

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Technical Specs - Overview

• ORP Broadcast is performed at set intervals Ok
  because medium usage is minimal in ORP Broadcast
  (vs. flooding)
• Probe and broadcast packets have a TTL associated
  with them to stop continuous send
• First rendezvous node found will be used to
  forward packets (even though atleast 2 will be
  found this will help choose better paths)

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Technical Specs Packet Info

• ORP Broadcast Packet - Periodic packets sent to
  update location in highly mobile environments
• ORP Probe Packet - Find a Source to Destination
  Rendezvous Node to send packets
• ORP Probe Packet ACK - Rendezvous Nodes that send
  ACKs will give the sender a more specific
  direction to forward packets. If no ACK is
  received, sender can still ORP Broadcast all
  their data but this is not suggested
• Data Packet Data to be sent

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Tech Specs Forwarding Tables

• Note only 1-hop tables maintained. Because of
  nature of ORP broadcast, forwarding tables might
  not include all immediate 1 hop neighbors

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Technical Specs - Algorithm

• ORP Broadcast
• Using local sense of direction, each node sends
  an ORP broadcast packet in orthogonal directions
• ORP Forwarding Table Build
• Upon receipt of ORP Broadcast PKT, build
  forwarding table (NB ID neighbor ID, Dir
  Direction, Dest ID Source of ORP Broadcast)
• If TTL on ORP Broadcast Packet not expired, send
  packet along path in same direction (send
  transceiver is 180 degrees from receive
  transceiver)

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Technical Specs - Algorithm

• ORP Probing
• When a node receives an ORP Probe Packet, check
  to see if we have the destination ID in our
  forwarding table
• If destination ID not in our forwarding table
• Add 180 degrees to the orientation of the
  transceiver that received it and send out of
  nearest transceiver
• Else
• Send ORP Probe ACK packet back through
  transceiver we received from

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Technical Specs- Algorithm

• Data Packet Forwarding
• - When a node receives an Data Packet, check to
  see if we have the destination ID in our
  forwarding table
• - If destination ID not in our forwarding table
• - Add 180 degrees to the orientation of the
  transceiver that received it and send out of
  nearest transceiver
• Else
• Send it in the direction of destination

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Key Obstacles to Overcome

• Alignment Issue
• Problem FSO links need alignment and line of
  sight
• Workarounds
• THz FSO can go through walls
• Previous work for tessellated transceivers allows
  for alignment by setting up a virtual
  omnidirectional environment
• Increase FSO beamwidth
• Sparse Network Issue
• Problem In sparse networks, what if ORP
  broadcast yields no returns?
• Workarounds
• Send broadcast packets on all FSO transceivers to
  simulate a traditional broadcast (other
  algorithms can be tested for more efficiency) in
  case of no response in all 4 directions.
• High Mobility Issue
• Problem High mobility makes rendezvous points
  obsolete quickly
• Workarounds
• ORP broadcast at set intervals
• Broadcasts can include movement trajectory
  information

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Simulation Parameters / Metrics

• Claim Connectivity Under Extreme Conditions
• Metric Data packet successful delivery
  percentage
• Conditions
• High Mobility
• Sparse Networks

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Simulation Results (todo)