Scalable Routing Protocols for Mobile Ad Hoc Networks Authors: Xiaoyan Hong Kaixin Xu Mario Gerla UCLA Presented by: Haoyuan Wang

contents Introduction Classification of ad hoc network protocols Brief introduction to each protocol Comparision of protocols in each category Conclusion

Mobile Ad Hoc Network Network that does not rely on a fixed infrastructure and works in a shared wireless media. Self-organizing and self configuring multihop wireless network. Each node functions not only as a host but also as a router that maintains routs to and forwards data packets for other nodes in the network that may not be within direct wireless transmission range.

Features of Routing Protocols for Ad Hoc Networks Must adapt quickly to frequent and unpredictable topology changes and must be frugal of communications and processing resources. Scalability issue is mostly concerned with excessive routing message overhead.

Classification of Ad Hoc Routing Protocols (according to network structure)

Fisheye State Routing LS type routing protocol. Maintaining a topology at each node. Exchange entire link state information only with neighbors in stead flooding it over the network. Link state exchange is periodical instead of event driven. Period is in lower frequency for faraway entries. Produces better path and distance about neighbor than faraway ones. Be more and more accurate as the packet approaches destination.

Optimized Link State Routing Protocol It is LS protocol. Differs from pure LS in two aspect. Only the MPR nodes of A need to forward link state updates. Link state update of node A is reduced. Particularily suited for dense network.

Topology Broadcast Based on Reversed Path Forwarding Consists of two different modules: neighbor discovery (TND) routing TND is performed through periodical ‘differential’ HELLO message to report the change of neighbor. Routing module is performed based on partial topology info. Obtained through both periodical and differential topology updates. Topology changes faster, generates less routing overhead and uses a smaller topology update packet size than pure LS .

Ad Hoc On Demand Distance Vector Routing Has route discovery phase query packets are flooded into the network by the source to find a path. Transit nodes learn the path to the source and enter the route in the forwarding table. Destination receives the query and use the traced path to respond to the source. Query packet is droped if it encountered a node which already has a route to destination.

Dynamic Source Routing Has route discovery phase uses source routing. query packet copies in its header the Ids of the intermediate nodes as it traversed. Destination retrieves the entire path from query packet and use it to respond to the source. Agressively catches the route discovery to minimize the cost incurred by route recovery.

Characteristics of Flat Routing Protocols N: number of nodes in network. e: number of communication pair

Clusterhead-Gateway Switch Routing Network is partitioned into clusters. Each cluster has a clusterhead. Gateway connects two clusters. Data packets are routed as repetition of “Clusterhead-Gateway…”. A cluster member table and DV table are maintained. Cluster member table records the cluster head for each node and is broadcasted periodically. Routing table maintains one entry for each cluster recording its path to destination. To route a packet, current node looks up clusterhead of destination from cluster member table, then find next hop to destination cluster in routing table, then route packet to destination clusterhead.

Hierarchical State Routing Use logical hierarchical topology by recursively clustering. Node at the same logical are grouped into clusters. Elected clusterhead at low level are members of the next higher leval. New members in turn organize themselves in clusters. Clusterhead summarizes link state info. Within its cluster and propagate it to neighbor clusterhead via gateway each physical node has ‘hierarchical’ topology info..Network is partitioned into clusters.

Zone Routing Protocol Hybrid of table-driven and on-demand routing. Each node has a predefined zone centered itself in terms of hops. Nodes inside zone, use table-driven protocols. Nodes outside the zone, use on-demand routing protocols. Hybrid proactive/reactive scheme limits the proactive overhead to only the size of the zone, and the reactive search overhead to only selected border nodes

Characteristics of Hierarchical Routing Protocols N: nodes in the network. M: avg. Number of nodes in a cluster. L: avg number of nodes in local scope. G: logical groups e: comm. Pairs H: number of hierarchical levels

Geographic Addressing and Routing GeoRouter calculates its service areaas the union of networks attached to it( a polygon). Data packet  local Geonode  GeoRouter  check service area  if not fully covered, copy packet to parent  check child routers‘ service area  if router’s service area falls in the target area, router pick up the packet  forwards to GeoNode.

Location Aided Routing Scheme 1: Source calculate expected zone and request zone. Flood route request only in request zone. Scheme 2: source calculate distance to destination. Node will relay route request message if the distance to the destination is less than or equal to the distance in he request message.

Distance Routing Effect Algorithm for Mobility Takes into account the distance effect and mobility rate. The greater the distance, the slower the move with respect with each other the faster the node moves, the more frequently it need to advertise its new location. With location info. In the routing table, data packets are partially flood to nodes in the direction of destination. Destination ACK the source in the similar way when receiving data.

Characteristics of GPS assisted Routing N: nodes in the network. M: avg. Number of nodes in a cluster. e: comm. Pair

Conclusion All protocols address challenges in terms of scalability. Routing strategy differs from various design consideration. Each offers different, competetive, and complementary advantages. Routing protocols capable of adapting to various domains are desirable in design.