Scalable Geographic Routing for Mobile Ad-hoc Networks (Joint work with Xiaojing Xiang and Zehua Zhou)

1
Scalable Geographic Routing for Mobile Ad-hoc
Networks(Joint work with Xiaojing Xiang and
Zehua Zhou)

• Xin Wang
• Assistant Professor
• Director, Wireless and Networking Systems Lab
  (WINS)
• SUNY, Buffalo
• http//www.cse.buffalo.edu/xwang8

2
Future - Common Network, Common
Applications

3G CellularNetworks
RadioController

AccessRouter
UrbanNetworks

• Outdoor Areas
• High Mobility

AggregationRouter

• Broadband Distribution Networks
• High Speed Pico Cells
• Broadband
• Wireless

Presence
EnterpriseNetworks
Location
AccessRouter

• 802.11
• Local Mobility
• Packet Voice
• High Data Rates

Core InternetBackbone
AggregationRouter
AggregationRouter
Authentication

HomeNetworks
AccessRouter

• DSL/Cable
• Community
• wireless
• networks

Ad HocNetworks
4GRadios

• Allow Peer-to-Peer Communications
• Self Configuring

3
Talk Overview

• Background and motivation
• Part I Self-adaptive geographic unicast routing
• Part II Scalable geographic multicast routing
• On-going and future work

4
Background

• Mobile Ad Hoc Networks (MANET)
• Self organized networks with no fixed
  infrastructure
• Example applications disaster area, military,
  sensor networks, wireless mesh networks
• May need to traverse many hops due to limited
  radio range
• Routing find a packet
  delivery path
• Unicast one-to-one
• Multicast one-to-many
  or manyto-many

5
Challenges of MANET Routing

• Host mobility leads to dynamic topology
• Rate of link failure/repair increases with moving
  speed
• Topology and routing path maintenance become more
  difficult with the increase of path length and
  node density
• Mobile devices have very limited energy, and
  small devices such as sensors have very limited
  per-node resources

6
Existing Unicast Routing Protocols

• Proactive protocols (DSDV, OLSR)
• Maintain routes continuously, large overhead when
  there is no traffic
• Actively track network topology changes, not
  suitable for high mobility

• Reactive protocols (DSR, AODV, TORA, FLR)
• Maintain routes only if needed
• May need network-wide flooding to discover
  routes, larger delay due to searching for path
  before sending packet

• Hybrid protocols (ZRP, SHARP)
• Combine the proactive and reactive approaches

• Geographic routing protocols (GPSR, GFG)
• Make use of location information to reduce
  routing overhead
• Only need to be aware of local topology

7
Information Required for Geographic Routing

• A nodes own position obtained through
  positioning service such as GPS

• The position of the destination determined
  through location service

• The positions of all neighbors learned through
  periodic beacons sent by neighbors

8
Forwarding Formats

• Greedy forwarding
• Make local optimal forwarding
  decision, choose the neighbor closest to the
  destination as next hop.

D
x
9
Problems with Classical Geographic Routing

• Proactive fixed-interval beaconing for positions
• Generate unnecessary overhead and consume energy
• Create collisions with normal data transmissions
• Beaconing interval affects accuracy of the local
  topology and routing performance
• Outdated topology gt non-optimal routing,
  transmission failures gt more network resource
  consumption
• Continuous retransmissions due to inaccurate
  position
• Reduce link throughput and fairness, and increase
  collisions gt further delay and energy consumption

10
Possible Performance Improvement

• Change Beacon Sending Interval
• Send out beacons only after moving a certain
  distance
• Send beacons more frequently, e.g. piggyback
  position with packets (Are the sending nodes the
  best next hop? )

Does not consider traffic conditions. May
generate unnecessary beacons.

• Do not use Beacons (CBF03, BLR04)
• Focus only on finding the next hop for greedy
  forwarding, and there is no recovery strategy
• Do not have a good strategy to cache the path
  detected or perform any route optimization.

11
Talk Overview

• Background and motivation
• Part I Self-adaptive geographic unicast routing
• Part II Scalable geographic multicast routing
• On-going and future work

12
Our Contributions

• Propose two self-adaptive routing protocols

BIGR Beaconless Interactive Geographic Routing
BTGR Beacon-on-Trigger Geographic Routing

• On demand alleviate unnecessary overhead due to
  proactive beacons

• More flexible position distribution more updated
  topology, more efficient routing and less failure
  

• Self adaptive adaptive to traffic pattern and
  robust to topology changes

13
Importance of updated positions some analysis

• Positions obtained may become outdated
• A mobile may move out of transmission range
  before the position is timed out and removed from
  neighbor table.
• Analysis assumptions
• Node B sends beacons periodically to refresh its
  position at A
• Neighbor area of A centered at A, within
  transmission range R
• Moving area of B centered at B, within maximum
  distance r

Neighbor time-out interval t
Bs speed relative to A
Current distance between A, B
Maximum distance traveled by B after t
14
Different Scenarios
R
R
r
z
z
A
B
R
r
A
B
z
B
A
r
Same as this case
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Probability of Moving Out of Range
Case 1
Case 2
Case 3
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Probability of the mobile moving out-of-range
(expressed in percentages)
Timeout
Vmax 4s 6s 8s 10s 12s 14s
10m/s 3.57 5.49 7.51 9.64 11.88 14.27
20m/s 7.51 11.88 16.80 22.43 29.19 38.26
30m/s 11.88 19.51 29.19 42.94 55.38 65.24
40m/s 16.80 29.14 47.37 62.22 72.89 80.07
50m/s 22.43 42.94 62.22 75.00 82.64 87.24
17
Proposed Geographic Routing Protocols

• BIGR Beaconless Interactive Geographic Routing
• BTGR Beacon-on-Trigger Geographic Routing

18
Beaconless Interactive Geographic Routing (BIGR)

• There is no beacon, routing path is built
  on-demand

• Route searching phase
• Route optimization phase

• Forwarding decision made through the cooperation
  of forwarding node and its neighbors
• Forwarding path optimized jointly by sending node
  and its neighbors

How to find next hop without positions of
neighbors?
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Route Searching

• After a route searching, a node keeps a record
  for next hop

Destination F
Dests position, time (x_F, y_F), t
NextHop C
New position, time (x_new, y_new), t_new
Old position, time (x_old, y_old), t_old
Transmission mode greedy or recovery
Next-hop position
A
F
Next hop table for node B
B
C
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How to find next hop?

• When a node (C) does not have next hop
  information, broadcast REQ

S
E
F
B
M
L
C
J
A
G
H
D
I
K
N
Within neighborhood
Dest DestPos SendPos Hop
D XD, YD Xc, Yc 1
A node that receives a packet for the first time
REQ message with
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Forwarding Node Selection

• Reply sending nodes closer to destination
  respond after a competition delay, and the delay
  is smaller for a node closer to destination

• Reply suppression a node cancels its reply if it
  overhears packet forwarding, or overhears reply
  sent by node closer to destination

• Multiple replies select the node closer to the
  destination as next hop

S
E
F
B
M
L
C
J
A
G
H
D
I
K
N
Dest Sender SendPos Hop
D G XG, YG 1
REPLY message
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Packet Sending

• Cs next hop table

Destination D
Dests position, time (x_D, y_D), t
NextHop G
New position, time (x_new, y_new), t_new
Old position, time (x_old, y_old), t_old
Transmission mode greedy
S
E
F
B
M
L
C
J
A
G
H
D
I
K
N
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Recovery from Local Void

• Without local topology, cannot use perimeter
  forwarding. How to recover?

• Broadcast REQ to N-hop neighbors

F
E
S
B
M
C
L
J
A
D
H
I
K
G
N
Dest DestPos SendPos Hop
D XD, YD Xc, Yc 2
REQ message with
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Finding Path in Recovery Mode

• Reply sending

• If one-hop neighbor is nearer to destination, it
  replies with Hop 1 Otherwise continues
  broadcasting REQ
• A two-hop neighbor nearer to destination replies
  (reverse path), Hop 2

• Reply suppression drop the REPLY if having
  forwarded/overhead one from the node closer to
  destination

• Multiple replies select the node closer to
  destination

F
E
S
Dest Sender SendPos Hop
D G XG, YG 2
B
M
C
L
J
Reply message
D
H
I
K
G
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Position Update and Route Optimization

• Update next hop position when overhearing packet
  forwarding by next hop (carrying sending node
  position)

• Validate next hop
• Estimate next hop
• If both old and new positions are fresh
• If only new position is available, it will be
  used as the estimated position
• Search for new route
• If both old and new positions are outdated
• If estimated position is out of transmission
  range or no longer closer to destination than
  current forwarding node

• Optimize routing path three cases

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Case 1 A is the destination

• As A is the destination, B should send packet
  directly to A, so A sends CORRECT to B

A
B
C

• B sets its next hop to A

Old path
Old position
Current position
New path
27
Case 2 Greedy Mode Forwarding
A
F

• If A is closer to F than C is to F, A sends
  CORRECT to B

B
C

• B compares As and Cs positions to F, and sets
  its next hop to A if it is closer to F

Greedy
Old position
Current position
Old path
New path
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Case 3 Recovery Forwarding
F

• If A is closer to F than that from B and C, A
  sends CORRECT to B
• If B is the first hop of recovery, if A is closer
  to F than B is to F, then A is closer to F than
  both B and C
• If B is the last hop of recovery, if A is closer
  to F than C is to F, then A is closer to F than
  both B and C

A
D
B
C
Recovery mode
Greedy

• B compares A and Cs positions relative to F, if
  A is closer to F, B sets its next hop to A

Old position

• If B is the first hop of recovery, change mode to
  greedy

Current position
Old path
New path
29
Proposed Geographic Routing Protocols

• BIGR Beaconless Interactive Geographic Routing
• BTGR Beacon-on-Trigger Geographic Routing

30
BTGR Beacon-on-Trigger Geographic Routing

• Position distribution through beacons
• Packet forwarding
• Send packet through greedy forwarding in general.
• Use perimeter forwarding in recovery mode.

• Beacon generation triggered by data traffic and
  route optimization
• Adaptive to traffic
• Send beacon periodically when overhearing data
  forwarding or requested by neighbor
• Stop beaconing if there is no traffic
• Route optimization
• Broadcast a beacon upon detecting non-optimal path

• Topology maintenance
• Only maintain positions of neighbors when there
  is traffic

31
Beacon Triggering by Non-optimal Path

• Route validation
• Delete invalid neighbors
• Update the positions of other members based on
  estimation
• Route optimization also three cases
• The first two cases are similar to those of BIGR
• Case 3 When A overhears forwarding from B to C
  using perimeter mode
• If A is closer to the destination than that of
  the node position where the perimeter mode
  started, B should resume greedy forwarding
  earlier
• A broadcasts a beacon to refresh its position, B
  will send future packets to A

32
Performance Studies

• Setup
• Tool GlomoSim
• Network size 3000 m x 1000 m, 300 nodes
• Traffic 30 CBR with rate 8kbps each
• Mobility model Random Waypoint
• Measures
• Packet delivery ratio
• The ratio of packets delivered to those
  originated by the source
• Control overhead
• The number of control messages over the number of
  packets received
• Average number of data packet transmissions
• The total number of packet transmissions
  accumulated from each hop over the total number
  of packets received
• Average end-to-end delay
• Average time interval for packets to traverse
  from source to destination

33
Performance Impact of Mobility

• Delivery ratio Control
  overhead

34
Performance Impact of Mobility (cont)
Total transmissions Average end-to-end
delay
Our protocols have significantly lower
transmission redundancy and end-to-end delay than
GPSR due to more updated topology.
35
Summary of Part I

• Propose two self-adaptive on-demand geographic
  routing protocols
• Alleviate unnecessary overhead due to proactive
  beacons
• More efficient position distribution and very
  robust to topology change packet transmission
  delay is reduced more than three times at high
  mobility as compared to GPSR
• Outperform existing geographic protocols in all
  test scenarios, including mobility, node density
  and traffic load

36
Talk Overview

• Background and motivation
• Part I Self-adaptive geographic unicast routing
• Part II Scalable geographic multicast routing
• On-going and future work

37
Existing Multicast Routing Protocols

• Tree-based (AMRIS, MAODV, LAM)
• Utilize network resources efficiently
• Mesh-based (FGMP, CAMP, ODMRP)
• Robust

Difficult to scale due to overhead for route
searching, group membership management, and
tree/mesh maintenance over dynamic topology

• Geographic multicast (LGT, DSM, PBM)
• Only consider packet forwarding scheme
• Reduce topology maintenance overhead, but not
  scalable

38
Why Is Geographic Multicast Difficult to Scale?

• Putting the information of all group members into
  packet header creates excessive overhead for
  large group

• Relying on location service to obtain positions
  for all group members adds more overhead

39
Our Contributions

• Design an efficient on-demand hierarchical group
  membership management scheme

• Use geographic forwarding to avoid building and
  maintaining tree/mesh structure

• Introduce the home zone to avoid periodical
  network-range flooding of source information

• Combine group membership management with
  location service to avoid location searches for
  group members

40
Terms Used in SGMP
41
SGMP Basic Principles
Join
Join
(RERESH)
(REPORT)
Zone Leader
Member
Source
Data
Data
Member Zone
Member
Source
Packet sending geographic unicasting, and the
packet for a zone is sent towards the zone
center.
42
Source Announcements

• A source
• At session initiation time, floods an ANNOUNCE,
  with address, position, and group ID
• Later piggybacks its information with the
  multicast packets
• A node interested in being a member
• Records source information

43
Home Zone Management

• Home zone information update
• Home zone searching
• Home zone election

• A source sends its zone ID to home zone when
  moving to new zone
• The first home zone node floods source info to
  whole zone

• Other nodes search home zone with ring of
  increasing size.
• Source announces its current zone as home zone,
  and sets sequence number to 0 Sequence number
  increases by one each time home zone changes.

• Will be triggered when a node receives a message
  addressed to home zone with ID different from
  record (due to zone update or zone announcement
  from a new source)

44
Membership Management within Zone

• A member
• A leader

45
Membership Management at Upper Tier

• Source records the member zones

Leader knows source location
Membership report
SOURCE message
Home Zone
Leader does not know source location or Source
information is outdated
46
Moving between Zones

• When a node moves into a new zone
• Clears old zones information
• If the node is a group member
• Will continue receiving packets forwarded by old
  zone
• Sends REFRESH to new zone leader
• When a leader is moving out of a zone
• Hands leadership to other nodes

47
Empty Zone Problem
20 40 60 80 100
100m 74.885 56.282 44.864 36.865 30.853
200m 36.857 19.208 10.985 6.5467 3.9951
400m 6.4964 0.9643 0.1605 0.0281 0.0051
600m 0.5930 0.0112 0.0002 5.4E-06 1.2E-07
48
Empty Zone Handling

• Member zone
• The departing leader notifies the source
• Home zone
• The last node announces the new zone it is moving
  to as the home zone floods source information
  within new home zone sends ANNOUNCE to network
  with sequence number of home zone increased by one

49
Multicast Packet Delivery

• Source
• Sends packets to all member zones and members in
  its zone
• Aggregates transmissions and sends one copy if
  several members share next hop

• Intermediate nodes
• Take similar action
• If the message includes their current zone,
  replace zone ID in the message with the
  information of the members in the zone.

Source
Zone leader
Group member
Other nodes
50
Performance Impact of mobility

• Delivery ratio Control overhead

51
Performance Scalability
Group size Network size
52
Summary of Part II

• Design a scalable geographic multicast routing
  scheme
• Scalable and robust group membership management
  and packet forwarding in terms of group size,
  network range and mobility
• Avoid the need to build and maintain the
  tree/mesh structure over dynamic topology
• Avoid network-range flooding of source
  information and location searches for the group
  members

53
On-going and Future Work

• Cross-Layer Optimization and Design of Mobile and
  Wireless Systems
• Create infrastructure and algorithms to enable
  more optimal performance of the wireless system,
  by adopting an integrated, multi-layer approach
• On-going projects
• Power control and energy efficient transmissions
  in mobile Ad Hoc networks
• Architecture design and cooperative resource
  management for IP-based radio access network

54
On-going and Future Work (cont)

• Next Generation Mobile Wireless Network
  Infrastructure and Service
• Development of network infrastructure and
  services over emerging radio and computing
  technologies.
• On-going projects
• Sensor Network Applications and Services
• Programmable Wireless Networking and Service
  Infrastructure Design
• Scalable and Resilient Wireless Mesh Network
  Design
• Context-aware Mobile Computing and Wireless
  Services
• Architecture and Design for Heterogeneous Networks

55

Q A
56
Home Zone Election

• When a node receives a message carrying home zone
  ID different from that in its record
• If the message has larger sequence number,
  update its home zone info otherwise, forward the
  message to recorded home zone

Home Zone SEQ 0
Membership report
SOURCE message
Home Zone SEQ 1
57
Membership Reporting in Local Zone

• A group member sends REFRESH to leader to report
  its membership
• If leader is known, unicast
• If leader is not known, elect leader
• Leader election (on demand)
• Flood the REFRESH, indicating leader information
  is requested
• A leader will send back a LEADER message
• If no LEADER is received, the member announces
  itself as the leader and floods a LEADER message
  within the zone

Zone leader
Group member
Other nodes
58
Impact of node density
59
Impact of node density (cont)
60
Impact of traffic load
61
Impact of traffic load (cont)
62
(No Transcript)
63
Tomorrow Common Net, Common Apps

3G CellularNetworks
RadioController

AccessRouter
UrbanNetworks

• Outdoor Areas
• High Mobility

AggregationRouter

• Broadband Distribution Networks
• High Speed Pico Cells

Presence
EnterpriseNetworks
Location
AccessRouter

• 802.11
• Local Mobility
• Packet Voice
• High Data Rates

Core InternetBackbone
AggregationRouter
AggregationRouter
Authentication

HomeNetworks
AccessRouter

• DSL/Cable
• High Speed Internet Access

Ad HocNetworks
4GRadios

• Allow Peer-to-Peer Communications
• Self Configuring

• Unifies access technologies (wireless and
  wireline)
• End-to-end Internet Service
• common mobility management and control
• common transport infrastructure
• common services infrastructure

64

• Architecture and Design for Heterogeneous
  Networks
• Enable end-to-end communications over
  heterogeneous networks WPAN, WLAN, WMAN, W-WAN,
  and Internet.
• Secure and Cooperative Routing over Ad Hoc
  Networks
• Provide security and incentive to enable the
  relay-based hop-by-hop transmissions.

65
Beacon Triggering by Data Traffic

• Three types of beacons (for position information)
• BEACON message
• REQ (Carrying position)
• Data packets (Carrying position)
• Beacon request
• Receiving REQ
• Overhearing data transmission
• Beacon sending
• Only if the request interval is smaller than
  threshold
• For packet sending
• Use local topology information for forwarding if
  request sent interval is smaller than threshold
• Otherwise, send REQ to neighbor

66
Route Searching

• How to find a path without beacon?
• Depend on forwarding states greedy or recovery
  
• Greedy forwarding
• Find a neighbor closest to the destination
• Recovery forwarding
• How to forward when there is no neighbor closer
  to the destination?

67
Membership Management in Local Zone

• Membership reporting by mobiles nodes
• Leader election
• Moving between different zones

68
Membership Management at Upper Tier

• A source needs to record the member zones
• Source announcement
• Home zone election
• Zone membership reporting

69
Protocol Overview

• Group membership management
• Packet forwarding

• At local zone tier, a leader will collect the
  positions and membership of the member nodes in
  the zone.
• At upper tier, the leader will represent the
  member zone to join a multicast tree.
• At upper tier, the source sends a packet to
  member zones At lower tier, the first node in
  the zone that receives the data packet forwards
  it to the group members.
• Both data and control packets are generally
  transmitted through geographic unicasting
  Packets for a zone are sent towards the zone
  center

Location of group members is combined with
group membership management