Dual-Region Location Management for Mobile Ad

Hoc Networks

Yinan Li, Ing-ray Chen, Ding-chau Wang

Presented by Youyou Cao

Introduction

• MANET: A self-organizing and self-configuring infrastructureless network of mobile devices connected by Wireless

• Problem: No good scalable location management for MANET yet!

Outline

• Introduction• System Design• Performance Model• Evaluation• Conclusion

Existing location management scheme

• Each node is assigned a home region(serve as location servers) through hashing

• Drawback: need to contact location server even source and destination nodes are close to each other

Home region of destination node

Destination node

Source node

How to improve?

• Periodically exchange location info with neighboring nodes in its local region

• If a node in the local region knows the location of destination node

Local region of source node

Source node

Destination node

Local region of destination node

- Only local location info of the neighbor is needed

How to improve?

• Even better, source node might be within the local region of the destination node

Source node

Destination node

Local region of destination node

- Only need local info from the node itself!

How to improve?

• Further question: how to define home and local region size?• Previous work:

- Define home region size statically at design time• Our work:

- Dynamically determine the optimal home region size and local region size

- in order to minimize the overall network cost incurred by location management and data packet delivery

System Design

• Assumptions:

- Mobile nodes knows their location, moving direction, moving speed via GPS

- Density of mobile nodes are high enough so there is at least one location server in each node’s home region

Dual-Region Mobility Management (DrMoM)

• Global Partition: Equally sized rectangular region

• Each node is permanently assigned a home region by hashing

• Home region center is fixed, Home region size is dynamically chosen based on node mobility and service characteristics.

Dual-Region Mobility Management

• Local region center moves when node moves, local region size chosen dynamically

• Local region location updates follow a threshold-based approach, ie, notice neighbors when its current location is outside of the transmission rage of its last updated location

Increase :

- Chance of successful location query increase

- Larger overhead for location queries and updates

Key Parameter: home region size

Key Parameters: local region size

Increase :

- Chance of locate destination node using only local info increase

- Cost of location inquiry packet delivery increase

- Rate of location updates of the home region decrease

Location Table

Each node maintain two tables:

• Home region location table

- Stores location information of nodes for which it serves as a location server

• Local region location table

- Stores location information of nodes for which it is within their location region

Greedy geographical packet forwarding

For each hop, select the node that is closest to the destination within its one hop neighbors

Performance Model

• Goal: minimize total communication cost incurred by DrMoM- Total number of wireless transmissions per time unit

• Impact of using this metric:- Small saving in cost can be significant over time

- Larger probability of successful packet deliveries

- Shorter average packet delay

- Maximize the lifetime of a MANET

Performance Model

• Assumptions:- Use modified random way point mobility model to simulate the movement of mobile nodes

- Hash function maps any mobile node uniformly to any rectangular region with equal probability

Notation Table

Notation

Broadcast cost b(R): the number of wireless transmissions to cover the entire region

: Average # of hops between node and its home region: Average distance between a node and its home region in a m*m square area

Location Update Cost

:The cost for local region location updates: broadcast updates to its neighbors

:The cost for home region location updates: send updates messages to home region first, then broadcast

Location Query Cost

the cost for local region location query: broadcast and collect reply from local neighbors

the cost for home regionlocation query: send request and get response from home region

Probability that local regionlocation query fails

Node densityProbability that a neighbor of S is also in local region or home region of D

Data Packet Delivery Cost

Upper bound: Upper bound:

p1(p2) : – probability that S is within the local(home) region of D

Case 1: A valid entry for D exists in Case 2: A valid entry for D exists in

Case 3: No valid entry for D exists in or

Home Region Maintenance Cost

When node B enter the home region of node A, A’s home region nodes broadcast the message to their neighbors

Total Communication Cost

Data Packet Rate Local region location update rate

Home region location update rate Home region maintenance rate

Performance Evaluation

Effect of () on the performance of DrMoM

Performance Evaluation

Total communication cost vs and in DrMoM

Performance Comparison

Total communication cost incurred per time unit by DrMoM vs SLURP and RUDLS as a function of φ, ν, n

Conclusion

• Designed a dual-region location management scheme to minimize overall network cost incurred for location management and data packet delivery that outperforms state-of-the-art schemes

• Dynamically identify and apply optimal and to each mobile node based on runtime mobility and service characteristics

• Application: build lookup table of optimal and at static time, check and apply optimal value at runtime

Future work

• Consider other mobility model rather than random movement

• Use stochastic Petri Net modeling technique• How to select trustworthy nodes as location

server when there is attack• Extend the design notion to other location-

based services in MANET

Thank you!

Questions?