A Network Layer Based Architecture For Service Discovery In Mobile ADHOC Networks

1
A Network Layer Based Architecture For
ServiceDiscovery In Mobile AD-HOC Networks

• Supercomputing Lab.
• Uram H. Yoon (07. 02. 13)

2
Contents

• Jxta-C Architecture
• Jxta Discovery Scenario
• Jxta-C Protocol
• Code Example

3
Discovery Protocols

• For Infrastructure
• Utilize Directories
• Directories manage service advertisement
• Often runs on a dedicated server
• For MANET
• Dynamic Topology
• High overhead
• Do not utilize directories

4
Motivations

• Use Directories in MANET
• Clustering is used
• Groups mobile nodes based on their locations
• Assign a node as a gateway at a node
• Service Selection
• Context aware protocol
• Ex) Distance

5
GRID protocol

• Every node has
• Location information of their own
• Synchronized clocks
• Based on GRID
• Consider geographic location information
• Maps physical location into 2d grids.
• A host dedicated to be the gateway at each grid
• The closest node to the center will be elected as
  a gateway
• Range of the grid should be small enough
• Gateway should be able to communicate withother
  gateways

6
Two special cases in GRID protocols

• Gateway leaves its grid
• Routing table is broadcasted to rest of the node
  in the grid
• Called Hand-Off
• Gateway election procedure will be started
• Source or Destination node moves
• Re-establish route without route discovery all
  over again

7
Hexell Routing Protocol

• Grid instead of square is used
• Better approximate radios range
• 6 immediate neighbor cells
• Reasons to go with GRID protocols
• Reactive protocol
• Performs better in simulation
• Fully location aware
• Yield better performance for forming cluster
• Utilizes the idea of a gateway
• Responsible for rout discovery, packet forwarding
  and route maintenance

8
Service Discovery

• Initial service discovery
• Provide the user with a lost of possible
  candidates
• Tree structure is used to organize service
  advertisement
• Service providing node forward the service
  advertisementto cells gateway
• Keep the advertisement simple and short for
  fastdistribution

9
Service Directory

• Service advertisements are constantly distributed
• Gateway is responsible of
• Providing service directory services
• Forwarding service advertisements
• If advertisements is received
• Checks whether the service is within range
• Update service registry tree and forward it to
  othergateway
• If Hand-off occurs
• Service discovery protocol broadcasts the service
  registry tree to its previous cells

10
Tree structure registry
11
Service Discovery

• When a clients needs to search for a service
• Send query message to local gateway
• With Time / minimum advertisements requirements
• Upon meeting requirement or timeout
• Advertisements are sent to the client

12
Service Selection

• Every service type has standardized context
  information items
• Not every nodes is interested in same issues
• Mobile agent is used
• Moves from a service to another service
• Compute index values based on requirements of
  node
• Only index values not actual information are
  returned

13
Performance Evaluation
14
Performance Evaluation (Contd.)

• Success ratio is higher
• If node is moving a a slow speed
• Moving to different cells slow rate
• Mostly affected when a gateway moves
• Pending service discovery for nodes from a
  previous cellis dropped
• More service provider doe not affect successratio

15
Got any
Questions?