Scalable Geographic Routing for Mobile Ad-hoc Networks
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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. 4G Radios. 4G Air Interface.

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Xin wang assistant professor director wireless and networking systems lab wins suny buffalo

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


Future common network common applications

4GRadios

4G AirInterface

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


Talk overview

Talk Overview

  • Background and motivation

  • Part I: Self-adaptive geographic unicast routing

  • Part II: Scalable geographic multicast routing

  • On-going and future work


Background

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 many–to-many


Challenges of manet routing

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


Existing unicast routing protocols

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


Information required for geographic routing

Information Required for Geographic Routing

  • The position of the destination: determined through location service

  • A node’s own position: obtained through positioning service such as GPS

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


Forwarding formats

  • Perimeter forwarding (GPSR)

    • Calculate a planar sub-graph (no crossed-edges exist) from the local topology

    • Route around the perimeter of void area (that does not have neighbor closer to the destination) until greedy forwarding can be resumed

D

x

Forwarding Formats

  • Greedy forwarding

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

D

x


Problems with classical geographic routing

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 => non-optimal routing, transmission failures => more network resource consumption

  • Continuous retransmissions due to inaccurate position

    • Reduce link throughput and fairness, and increase collisions => further delay and energy consumption


Possible performance improvement

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 (CBF’03, BLR’04)

    • 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.


Talk overview1

Talk Overview

  • Background and motivation

  • Part I: Self-adaptive geographic unicast routing

  • Part II: Scalable geographic multicast routing

  • On-going and future work


Our contributions

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


Importance of updated positions some analysis

r

z

R

A

B

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


Different scenarios

r

z

R

A

B

r

z

r

A

A

z

R

R

Different Scenarios

R

R

r

z

z

A

B

R

r

A

B

z

B

A

r

Same as this case


Probability of moving out of range

Probability of Moving Out of Range

Case 1:

Case 2:

Case 3:


Probability of the mobile moving out of range expressed in percentages

Probability of the mobile moving out-of-range (expressed in percentages)

Timeout


Proposed geographic routing protocols

Proposed Geographic Routing Protocols

  • BIGR: Beaconless Interactive Geographic Routing

  • BTGR: Beacon-on-Trigger Geographic Routing


Beaconless interactive geographic routing bigr

Beaconless Interactive Geographic Routing (BIGR)

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

  • Forwarding decision made through the cooperation of forwarding node and its neighbors

  • Forwarding path optimized jointly by sending node and its neighbors

  • Route searching phase

  • Route optimization phase

How to find next hop without positions of neighbors?


Route searching

Route Searching

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

Next-hop position

A

F

Next hop table for node B

B

C


How to find next hop

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

A node that receives a

packet for the first time

REQ message with


Forwarding node selection

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

REPLY message


Packet sending

Packet Sending

  • C’s next hop table

S

E

F

B

M

L

C

J

A

G

H

D

I

K

N


Recovery from local void

Recovery from Local Void

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

  • Broadcast REQ to N-hop neighbors

E

F

S

B

M

C

L

J

A

D

H

I

G

K

N

REQ message with


Finding path in recovery mode

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

E

F

S

B

M

C

L

J

Reply message

D

H

I

G

K


Position update and route optimization

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


Case 1 a is the destination

Move

CORRECT

A

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


Case 2 greedy mode forwarding

Move

A

CORRECT

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 A’s and C’s 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


Case 3 recovery forwarding

Move

A

CORRECT

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 C’s 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 togreedy

Current position

Old path

New path


Proposed geographic routing protocols1

Proposed Geographic Routing Protocols

  • BIGR: Beaconless Interactive Geographic Routing

  • BTGR: Beacon-on-Trigger Geographic Routing


Btgr beacon on trigger geographic routing

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


Beacon triggering by non optimal path

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


Performance studies

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


Performance impact of mobility

BIGR and BTGR delivery ratios are not impacted by speed

BIGR more actively updates the position as speed increases

Performance: Impact of Mobility

Delivery ratio Control overhead


Performance impact of mobility cont

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.


Summary of part i

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


Talk overview2

Talk Overview

  • Background and motivation

  • Part I: Self-adaptive geographic unicast routing

  • Part II: Scalable geographic multicast routing

  • On-going and future work


Existing multicast routing protocols

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


Why is geographic multicast difficult to scale

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


Our contributions1

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


Terms used in sgmp

Source

Group member

Member Zone

Zone leader

Home zone

Track the addresses

and Zone IDs of

sources

Terms Used in SGMP


Sgmp basic principles

SGMP: Basic Principles

Join

Join

(RERESH)

(REPORT)

Member

Zone Leader

Source

Data

Data

Member

Member Zone

Source

Packet sending: geographic unicasting, and the packet for a zone is sent towards the zone center.


Source announcements

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


Home zone management

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)


Membership management within zone

  • Sends REFRESH to leader periodically and when joining /leaving group, carrying its membership and position

  • Floods LEADER periodically within the zone to announce its leadership, carrying its own position and the positions and group IDs of the multicast members

Membership Management within Zone

  • A member

  • A leader


Membership management at upper tier

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


Moving between zones

Moving between Zones

  • When a node moves into a new zone

    • Clears old zone’s 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


Empty zone problem

Empty Zone Problem


Empty zone handling

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


Multicast packet delivery

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


Performance impact of mobility1

SGMP has up to 35% higher delivery ratio and 20 % lower overhead at high mobility

Performance: Impact of mobility

Delivery ratio Control overhead


Performance scalability

SGMP has higher delivery ratio under all group sizes, and has more than 2.5 times higher delivery ratio for large network sizes.

Performance: Scalability

Group size Network size


Summary of part ii

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


On going and future work

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


On going and future work cont

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


Xin wang assistant professor director wireless and networking systems lab wins suny buffalo

Q & A


Home zone election

Forward

to home zone

with larger SEQ

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


Membership reporting in local zone

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


Impact of node density

Impact of node density


Impact of node density cont

Impact of node density (cont)


Impact of traffic load

Impact of traffic load


Impact of traffic load cont

Impact of traffic load (cont)


Tomorrow common net common apps

4GRadios

4G AirInterface

… 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

    • commonmobility management and control

    • common transport infrastructure

    • common services infrastructure


Xin wang assistant professor director wireless and networking systems lab wins suny buffalo

  • 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.


Beacon triggering by data traffic

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


Route searching1

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?


Membership management in local zone

Membership Management in Local Zone

  • Membership reporting by mobiles nodes

  • Leader election

  • Moving between different zones


Membership management at upper tier1

Membership Management at Upper Tier

  • A source needs to record the member zones

  • Source announcement

  • Home zone election

  • Zone membership reporting


Protocol overview

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


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