Proposed ad hoc Routing Approaches Conventional wired-type schemes (global routing, proactive): –Distance Vector; Link State Proactive ad hoc routing: –OLSR, TBRPF On- Demand, reactive routing: DSR (Source routing), MSR AODV (Backward learning) AODV-DFR Scalable routing : –Hierarchical routing: HSR, Fisheye –OLSR + Fisheye – LANMAR (for teams/swarms) Geo-routing: GPSR, GeRaF, etc Motion assisted routing

“Direction” forwarding for mobile, large scale ad hoc networks In Distance Vector Routing (e.g., Bellman Ford, AODV etc.) node keeps pointer to “predecessor” When the predecessor moves, the path is broken Alternate paths, even when available, are not used Sink Source DV update Predecessor Data flow  Proposed solution: direction forwarding  Distance Vector not robust to mobility

Direction Forwarding Distance Vector update creates not only “predecessor”, but also “direction” entry Select “most productive” neighbor in forward direction If the network is reasonably dense, the path is salvaged

How to compute the “direction”  Need “stable” local orientation system (say, virtual compass) to determine direction of update  Local (rather than global) reference is required;  Local reference system must be refreshed fast enough to track avg local motion  GPS will do (e.g., neighbors exchange (X, Y) coordinates)  If GPS not available, several non-GPS coordinate systems have been recently published  Sextant [Mobihoc ’05]; beacon DV; RFID’s etc

Computing the “direction”(cont)  Compute “direction” to a destination when DV updates are received:  If a DV update packet with a more recent Seq # or smaller hop distance is received:  New “direction” replaces the old one  The “direction” to the predecessor is used as the “direction” to the destination  If multiple DV updates received from different “predecessors” with same hop distance and seq # for the destination  Take vector sum of directions

Computation of the “direction” Where the polar angle is the radian from the x-axis that is used as the direction of the predecessor node. Suppose node A receives DV update packets from B & C  Compute the “directions” to predecessors node B & C, respectively, A C B “Direction” to a destination Unit vectors are used to combine the two “directions” Directions to predecessors

Direction Forwarding vs Geo routing Geo-routing: –Direction points to destination –This direction may be unfeasible (holes, etc) –Global geo-coordinates (eg, GPS) –Geo Location Server –Robust to mobility Direction Forwarding –Direction of updates (always feasible) –Local (not global) position reference system –Advertisements from destination –Robust to mobility

Robust Ad Hoc Routing for Lossy Wireless Environment Challenges for routing in mobile ad hoc network –Route breakage –High BER –Scalability The shortcomings of on-demand routing Not scalable for mobility The shortcomings of proactive routing Constant and high routing overhead The shortcomings of current Geo-routing Need Geo-Location Service, GLS “Face routing” is inefficient

Hybrid Routing: AODV-DFR ( AODV with Directional Forwarding Routing) Combines on-demand and proactive routing –When a source starts comm, it first finds the destination as in an on-demand fashion –Once the destination is notified, it initiates periodic routing updates in a proactive fashion Utilizing an alternate path instantly based on “direction” to the destination if a path fails –resemblance with Georouting in the update message –No location server system is required (not like GPSR)

AODV-DFR Source initiates route discovery a la AODV –Destination, or any node that has a route, replies –The path is set up Destination begins proactive advertisements (a la DV) after receiving data pkts from source –Intermediate nodes rebroadcast ads –Only for active connections –Period increases with distance from destination (Fisheye concept) Packet routing assisted by Direction Forward The destination stops advertisement if it does not receive pkts for some time

Performance Evaluation Compare AODV, AODV-DFR, GPSR and ADV (proactive and on-demand Hybrid Routing) –Performance: Delivery ratio, Packet delay, Routing Overhead –Mobile & lossy network: UDP and TCP traffic Mobility Speed Packet loss: uniformly distributed on a link Simulation –100 nodes randomly moving in 1000x1000m –The traffic pairs are randomly distributed over the network –UDP flows: pkt size 512 bytes, rate 1pkt/sec –TCP flows: NewReno, pkt size 1460 bytes

Mobile Network: Delivery Ratio 80 UDP flows

Mobile Network: Packet delay 80 UDP flows

Mobile Network: Routing Overhead 80 UDP flows

Mobile & Lossy Network: Delivery Ratio UDP Flow number: 80 Mobility Speed: 10 m/s

Mobile & Lossy Network: Routing Overhead UDP Flow number: 80 Mobility Speed: 10 m/s

TCP in Mobile Network 40 TCP flows

TCP in Mobile & Lossy Network TCP flow number: 40 Mobility: 10 m/s

AODV-DFR Contributions A hybrid routing: proactive + on-demand Robust to mobility and packet loss Utilize location information for directional forwarding with only local updates. Low overhead Provide better performance than AODV and GPSR Enhances AODV Competitive with GPSR (does not require “global” positioning such as GPS) Ongoing work: local coordinate system; integration of local and global coordinates (indoor+outdoor)

Robust Ad Hoc Routing for Lossy Wireless Environment CS 218 Fall 08 UCLA: Jiwei Chen, Yeng-Zhong Lee, Mario Gerla TJU: He Zhou, Yantai Shu Milcom 2006

Introduction Challenges for routing in mobile ad hoc network –Route breakage –High BER –Scalability The shortcomings of on-demand routing Not scalable for mobility The shortcomings of proactive routing Constant and high routing overhead The shortcomings of current Geo-routing Need Geo-Location Service, GLS “Face routing” is inefficient ENTER AODV-DFR!

Related Work Proactive Routing –OLSR, DSDV On-demand Routing –AODV, DSR Geographic Routing –GPSR and several others –greedy + face algorithm –GLS (geo location service) Hybrid Routing –ZRP, SHARP, LANMAR zone and group concept –ADV, proactive and on-demand –DREAM, proactive and geo-routing –AODV-DFR

AODV-DFR Source initiates route discovery a la AODV –Destination, or any node that has a route, replies –The path is set up Destination begins periodic advertisements (a la Distance Vector) after receiving data packets from source –Intermediate nodes rebroadcast advertisements - interval increases with distance from destination (Fisheye concept) Packet routing assisted by Direction Forwarding The destination stops advertisement if it does not receive packets for some time.

Proactive Advertising in AODV-DFR Only for active connections “Fisheye” updating frequency

Direction Forwarding Distance Vector update creates not only “predecessor”, but also “direction” entry Sink “Predecessor only” forwarding fails DFR selects “most productive” neighbor in right direction If the network is reasonably dense, the path is salvaged Source DV update Predecessor Data flow “Direction” to Sink

Directional Forwarding Each node remembers the local advertised directional Only local coordinates needed Direction is computed by the aggregation of local updates “Multiple hop” direction can also be available. Next node with min-hop and minimal deviation from the direction is selected.

Routing Tables at a Node Neighbor Table –Direction to all neighbors NB ID Seq Num Direction to NB Des t ID Hop Count Routing table –Routes to all active destinations Dest ID Direction to Dest Next Hop Hop Count

Performance Evaluation Compare AODV, AODV-DFR, ADV, and GPSR (without charge for GLS overhead). Performance in mobile network –Delivery ratio –Routing Overhead Performance in mobile & lossy network –Packet loss: uniformly distributed on a link –UDP and TCP traffic

Simulation Environment 100 nodes randomly moving in a 1000x1000m space The traffic pairs are randomly distributed over the network. UDP flows: pkt size 512 bytes, rate 1pkt/sec TCP flows: data pkt size 1460 bytes, NewReno

Mobile Network: Delivery Ratio 80 UDP flows

Mobile Network: Routing Overhead 80 UDP flows

Mobile & Lossy Network: Delivery Ratio UDP Flow number: 80 Mobility Speed: 10 m/s

Mobile & Lossy Network: Routing Overhead UDP Flow number: 80 Mobility Speed: 10 m/s

TCP in Mobile Network 40 TCP flows

TCP in Mobile & Lossy Network TCP flow number: 40 Mobility: 10 m/s

AODV-DFR Contributions A hybrid routing: proactive + on-demand Robust to mobility and packet loss Utilize location information for directional forwarding with only local updates. Low overhead Enhances AODV Competitive with GPSR: –not affected by GLS and by face routing issues; –does not require “global” positioning such as GPS Ongoing work: local coordinate system; integration of local and global coordinates (indoor+outdoor)