GPSR: Greedy Perimeter Stateless Routing for Wireless Networks pps

1 GPSR: Greedy Perimeter Stateless Routing for Wireless Networks B. Karp, H. T. Kung Borrowed some slides from Richard Yang’s 2 Motivation ❒ A sensor net consists of hundreds or thousands of nodes ❍ Scalability is the issue ❍ Existing ad hoc net protocols, e.g., DSR, AODV, ZRP, require nodes to cache e2e route information ❍ Dynamic topology changes ❍ Mobility ❒ Reduce caching overhead ❍ Hierarchical routing is usually based on well defined, rarely changing administrative boundaries ❍ Geographic routing • Use location for routing 3 Scalability metrics ❒ Routing protocol msg cost ❍ How many control packets sent? ❒ Per node state ❍ How much storage per node is required? ❒ E2E packet delivery success rate 4 Assumptions ❒ Every node knows its location ❍ Positioning devices like GPS ❍ Localization ❒ A source can get the location of the destination ❒ 802.11 MAC ❒ Link bidirectionality 5 Geographic Routing: Greedy Routing S D Closest to D A - Find neighbors who are the closer to the destination - Forward the packet to the neighbor closest to the destination 6 Benefits of GF ❒ A node only needs to remember the location info of one-hop neighbors ❒ Routing decisions can be dynamically made 7 Greedy Forwarding does NOT always work ❒ If the network is dense enough that each interior node has a neighbor in every 2Π/3 angular sector, GF will always succeed GF fails 8 Dealing with Void: Right-Hand Rule ❒ Apply the right-hand rule to traverse the edges of a void ❍ Pick the next anticlockwise edge ❍ Traditionally used to get out of a maze 9 Right Hand Rule on Convex Subdivision For convex subdivision, right hand rule is equivalent to traversing the face with the crossing edges removed. 1 0 Right-Hand Rule Does Not Work with Cross Edges u z w D x  x originates a packet to u  Right-hand rule results in the tour x-u-z-w-u-x [...]... collision 1 Greedy Perimeter Stateless Routing (GPSR) Ì Maintenance r r all nodes maintain a single-hop neighbor table Use RNG or GG to make the graph planar Ì At source: r mode = greedy Ì Intermediate node: r if (mode == greedy) { greedy forwarding; if (fail) mode = perimeter; } if (mode == perimeter) { if (have left local maxima) mode = greedy; else (right-hand rule); } 1 GPSR greedy fails Greedy Forwarding... Ì Geographic probabilistic routing, International workshop on wireless ad-hoc networks, 2005 r Determine the packet forwarding probability to each neighbor based on its location, residual energy, and link reliability 2 Ì Beacon vector routing, NSDI 2005 r Beacons know their locations r Forward a packet towards the beacon Ì A Scalable Location Service for Geographic Ad Hoc Routing, MobiCom ’00 r Distributed... problem, the graph should be re-planarize for every beacon msg r r Also, assumes a circular radio transmission model In general, it could be harder & more expensive than it sounds 2 Performance evaluation Ì Simulation in ns-2 Ì Baseline: DSR (Dynamic Source Routing Ì Random waypoint model r A node chooses a destination uniformly at random r Choose velocity uniformly at random in the configurable range... forwarding; if (fail) mode = perimeter; } if (mode == perimeter) { if (have left local maxima) mode = greedy; else (right-hand rule); } 1 GPSR greedy fails Greedy Forwarding greedy works Perimeter Forwarding have left local maxima greedy fails 1 Implementation Issues Ì Graph planarization r r r RNG & GG planarization depend on having the current location info of a node’s neighbors Mobility may cause... 22 sending nodes & 30 flows r About 20 neighbors for each node – very dense r CBR (2Kbps) Ì Nominal radio range: 250m (802.11 WaveLan radio) Ì Each simulation takes 900 seconds Ì Take an average of the six different randomly generated motion patterns 2 Packet Delivery Success Rate 2 Routing Protocol Overhead 2 Related Work Ì Geographic and Energy Aware Routing (GEAR), UCLA Tech Report, 2000 r Consider... r Beacons know their locations r Forward a packet towards the beacon Ì A Scalable Location Service for Geographic Ad Hoc Routing, MobiCom ’00 r Distributed location service Ì Landmark routing r Paul F Tsuchiya Landmark routing: Architecture, algorithms and issues Technical Report MTR-87W00174, MITRE Corporation, September 1987 r Classic work with many follow-ups 2 Questions? 2 . (mode == greedy) { greedy forwarding; if (fail) mode = perimeter; } if (mode == perimeter) { if (have left local maxima) mode = greedy; else (right-hand rule); } 1 9 GPSR Greedy Forwarding Perimeter. 1 GPSR: Greedy Perimeter Stateless Routing for Wireless Networks B. Karp, H. T. Kung Borrowed some slides from Richard Yang’s 2 Motivation ❒ A. subset Examples 1 8 Greedy Perimeter Stateless Routing (GPSR) ❒ Maintenance ❍ all nodes maintain a single-hop neighbor table ❍ Use RNG or GG to make the graph planar ❒ At source: ❍ mode = greedy ❒ Intermediate