Rendezvous Routing Protocol for Wireless Mesh Networks Bow-Nan Cheng Murat Yuksel Shivkumar Kalyanaraman
Dec 20, 2015
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: [email protected]
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!