Orthogonal Rendezvous Routing Protocol for Wireless

Mesh NetworksBow-Nan Cheng

Murat YukselShivkumar Kalyanaraman

By removing position

information, can we still efficiently

route packets?

Motivation

L3: Geographic Routing using Node IDs (eg. GPSR, TBF etc.)

L2: ID to Location Mapping (eg. DHT, GLS etc.)

L1: Node Localization

ORRP

N/A

Issues in Position-based Schemes

S

N

W E

(0,4)

(4,6)

(5,1)

(8,5)

(12,3)

(15,5)S

D

D(X,Y)? ?

Motivation – Multi-directional Transmission Methods

Multi-directional Antennas Tessellated FSO Transceivers

Directional communicationsModel needed for ORRP

45o 22.5o

ORRP Introduction

Up to 69%

A

B

98%

Assumptions Neighbors are

assigned a direction Local Sense of

Direction Ability to

Transmit/Receive Directionally

Directional, smart antennas

FSO transceivers

ORRP Design Considerations Considerations:

High probability of connectivity without position information [Reachability]

Scalability O(N3/2) total state information maintained. (O(N1/2) per node state information)

Even distribution of state information leading to no single point of failure [State Complexity]

Handles voids and sparse networks Trade-offs

Path Stretch Probabilistic Reachability

ORRP Proactive and Reactive Elements

Node C Fwd Table

Dest Next Cost Dir

A B 2 120o

D D 1 230o

Node B Fwd Table

Dest Next Cost Dir

A A 1 90o

A

B C

D1. ORRP Announcements (Proactive) –

Generates Rendezvous node-to-destination paths1

11

1

2. ORRP Route REQuest (RREQ) Packets (Reactive)

2

2

2

2

2

33

3. ORRP Route REPly (RREP) Packets (Reactive)4. Data path after route generation

4

4

Deviation Correction: Multiplier Angle Method (MAM) Concept

180o

=45o

45o=

45o=

180o

-90o=-

AB

C

D

E

F

G

m

negativemm

positivemm

,2,2

max

,2,2

min

Multiplier (m)

Desired AngleReceived Angle

Loop Prevention

Actual Tx Angle

Interface Separation Angle

Deviation Angle

New Multiplier (m)

Void

min(+46 = + 4m = +2

S Rmin(+4 = + m = +3

min(+4 = + m = 0

min(+44 = + 4m = +2

min(+44 = + 4m = +3

Multiplier Angle Method (MAM) Examples

Basic ExampleVOID Navigation/Sparse

Networks Example

min(+46 = + 4m = +2

ORRP Void Navigation – differences from GPSR perimeter routing

ORRP seeks only intersections between destination ORRP packets and source ORRP packets – increased flexibility

MAM is an inherent nature of ORRP and not a special case that switches on and off like GPSR perimeter routing

ORRP does not require location-id mappings as GPSR does

Performance Evaluation of ORRP Metric

Reachability – Percentage of nodes reachable by each node in network (Hypothesis: high reachability)

State Complexity – The total state information needed to be maintained in the network (Hypothesis: O(N3/2))

Path Stretch – Average ORP Path vs. Shortest Path (Hypothesis: Low path stretch)

Analysis (without MAM) Reachability Upper Bound State Information Maintained at Each Node Average Path Stretch

Packetized Simulation Scenarios Evaluated Effect of MAM on reachability Effect of finer-grained directionality Total state complexity and distribution of state

Reachability Numerical Analysis

P{unreachable} =

P{intersections not in rectangle}

4 Possible Intersection Points

1

2

3

98.3% 99.75%

57%

67.7%

Probability of Unreach highest at perimeters and corners

NS2 Simulations with MAM show

around 99% reachability

ORRP Perimeter Issue

Perimeter/Corner Nodes – Corner nodes have higher probability of orthogonal line intersections outside of topology bounding region

Path Stretch Analysis

Average Stretch for various topologies

• Square Topology – 1.255• Circular Topology – 1.15• 25 X 4 Rectangular – 3.24• Expected Stretch – 1.125

x = 1.255 x = 1.15

x = 3.24

State Complexity Analysis/Simulations

GPSR DSDV XYLS ORRP

Node State O(1) O(n2) O(n3/2) O(n3/2)

Reachability High High 100% High (99%)

Name Resolution O(n log n) O(1) O(1) O(1)

Invariants Geography None Global Comp. Local Comp.

ORRP state scales with Order N3/2 ORRP states are

distributed fairly evenly (no single pt of failure)

Reachability – Finer Grained Directionality (NS2 Simulations)

Observations/Discussions For sparse networks, reachability

increases dramatically as number of interfaces increases. This is due to more node choices to effectively route paths

Non-complete reachability even with MAM due to network “fingers”

Finer-grained interface spread have increased

effectiveness in sparse networks to a point

Finer-grained interface spread increases reach in networks with voids

Additional Results (in brief) MAM increases reachability to almost

100% even in rectangular topologies in NS2 simulations

Path stretch with MAM stays relatively constant even with finer granularity of antenna spread (discounting unreach)

Numerical Simulation of “additional lines” yields very little REACH and PATH STRETCH gain while adding a lot of additional state

Summary ORRP achieves high reachability in

random topologies ORRP achieves O(N3/2) state

maintenance – scalable even with flat, unstructured routing

ORRP achieves low path stretch (Tradeoff for connectivity under relaxed information is very small!)

Future Work Mobile ORRP (MORRP) Hybrid Direction and Omni-directional nodes More detailed abstraction to 3-D Route loop prevention ORRP for peer to peer networks requires the

concept of locally consistent virtual direction

Thanks!Questions or Comments: chengb@rpi.edu

Affect of Control Packet TTL on Varying Network Densities (NS2)

Observations/Discussions Reachability increases heavily when

TTL is increased from 2 to 7 but stays roughly constantly with continued increases (Saturation Pt.)

Total States increases dramatically from setting a TTL of 2 to 7 and then stays constant

Average path length remains unchanged with TTL

Reach increases until Saturation Pt with increase in TTL

Total States increases until

Saturation Pt with increase in TTL

Average Path Length Remains constant with

varying TTL

Additional Lines Study

Observations / Discussions Probability of reach is not

increased dramatically with addition of lines above “2”

Path stretch is decreased with addition of lines but not as dramatically as between “1” and “2”

Total States maintained is increased heavily with increase in number of lines

Motivation – Hybrid FSO/RF MANETs Current RF-based Ad Hoc

Networks: 802.1x with omni-directional RF

antennas High-power – typically the most

power consuming parts of laptops Low bandwidth – typically the

bottleneck link in the chain Error-prone, high losses

Free-Space-Optical (FSO)

Communications

Mobile Ad Hoc Networking

• High bandwidth• Low power• Directional – secure, more effective use of medium

• Mobile communication• Auto-configuration

Free-Space-OpticalAd Hoc Networks

• Spatial reuse and angular diversity in nodes• Low power and secure• Electronic auto-alignment• Optical auto-configuration (switching, routing)• Interdisciplinary, cross-layer design

State Complexity – Varying Number of Interfaces (NS2 Simulations)

Observations/Discussions Total States increases with the

number of nodes in the network (expected)

Total states is not very dependent on the number of interfaces

Increase in Total States maintained consistent with increased reachability (more states = more reachability)

Stretch – Average Path Length vs. Varying Interfaces (NS2 Simulations)

Observations/Discussions As node density increases, path

length increases as next hop nodes are chosen at random from the nodes within the transmission range + LOS. With more nodes, there is more choices of “closer nodes”

Average Path Length improves for dense networks with more interfaces. More interfaces increases granularity and limits node selection

ORRP IntroductionAssumptions Neighbor Discovery

1-hop neighbors Given direction/interface

to send packets to reach each neighbor

Local Sense of Direction Ability to Transmit/Receive

Directionally Directional, smart

antennas FSO transceivers

Deviation Correction: Multiplier Angle Method (MAM)

Number of Interfaces The angle node received packets from

Received Angle () The angle node received packets from

Deviation Angle () The angle to add/subtract that previous node deviated from desired angle when sending

Desired Angle () The desired angle to send out

Found Angle () The angle of transceiver found with neighbor closest to desired angle

Separation Angle () The angle of separation between each transceiver

Multiplier (m) The value to multiply by to find new desired angle

m

negativemm

positivemm

,2,4)(min

,2,4)(min

Important Notes:

1. Only corrections outside of antenna spread considered

2. MAM assumes that relative distances from one hop to another are relatively equal

3. All deviation correction done at RREQ and ORRP Announcement level (not on each transmission)

ORRP Packet Deviation Issue

Sending in orthogonal directions increases likelihood of intersections (Single line: 69% intersection vs. Orthogonal Lines: 98% intersection)

Packet deviation potentially lowers the likelihood of intersections (ie: if packets end up traveling in parallel paths)

Question: How can we maintain straight paths as much as possible without adding too much overhead to the system?

Thanks!

Can directionality be used at Layer 3? YES!