GeoTORA: A Protocol for Geocasting in Mobile Ad Hoc Networks Authors: Young-Bae Ko, IBM T.J. Watson Nitin H. Vaidya, Texas A&M University Speaker: Gavin Holland, Texas A&M University Good morning, everyone (ladies and gentlemen, Sir and Madam). My name is Young-Bae ko and I am very glad to be here with you today. I am gonna

Mobile Ad hoc Networks (MANETs) Network of mobile wireless nodes Do not require fixed infrastructure to communicate Form their own mobile routing infrastructure Characteristics Dynamic topology Low link bandwidth Limited power Applications Personal area networking Wireless home networking Search and rescue operations A mobile ad hoc network, so called MANET, is a set of wireless mobile nodes forming Nodes communicate directly with each other over either radio frequency or intrared wireless links

Geocasting Packets are delivered to all nodes within a geographical region Compared to multicasting Multicasting: nodes may join/leave group as desired Geocasting: nodes join/leave group by entering/leaving the geocast region Useful for delivering location-dependent information Sending fire emergency messages to a certain region Geocast Region K L C D A B G J E F

Geocasting in MANET Navas and Imielinski [Navas97] proposed the notion of geocasting in the traditional internet Need new protocols for geocasting in MANETs Ko and Vaidya[Ko99] proposed several flooding-based geocasting protocols Geocast flooding Location-Based Multicast (LBM)

Location-Based Multicasting Geocast Region A A C C Z Z B B W W Y Y Forwarding Zone X X Limit flooding of geocasts to forwarding zone Good when geocasting is performed infrequently High overhead

Proposed: GeoTORA Based on TORA (Temporally Ordered Routing Algorithm) [Park and Corson 97] Unicast routing algorithm for MANETs Destination-oriented directed acyclic graphs (DAGs) Uses “Link-Reversal” techniques to maintain DAGs GeoTORA Modify TORA to do anycasting Modify further to do geocasting

TORA (Temporally Ordered Routing Algorithm) B C A DAG is maintained for each destination A logical direction is imposed on the links towards the destination Starting from any node in the graph, a destination can be reached by following the directed links A D G F E

TORA – Link Reversal When a node has no downstream links, it reverses the direction of one or more links B C B C A D G A D G F F E E B C B C A D A D G G F F E E

Anycasting with Modified TORA In GeoTORA, the TORA protocol is modified to be able to perform anycast Anycast -deliver to any one node in the anycast group Protocol Maintain a DAG for each anycast group Make each member of the anycast group a sink No logical direction for links between sinks Following the directed links results in packets being delivered to any one sink

Anycasting Example Anycast group = {A, B, C, D}, DAG structure for the anycast group K K K L L L C D C D C D A B A B A B G J J J G G F F F E E E

Geocasting using Modified Anycasting Small variation on the previous anycasting All nodes within a specified geocasting region are made sinks Maintain a single DAG for a given geocast group Source first performs an anycast to the geocast group members When a group member receives a packet, it floods it within the geocast region K Geocast Region L C D A B G J F E

GeoTORA - Considerations Links may have to be updated K L when node C leaves geocast region when node K enters geocast region C D K L L C A B C K G J D D E F A B A B E F G J E F G J

Performance Evaluation Simulation Model (NS2 w/ CMU extensions) 30 nodes in a 700x700 unit arena 1000 geocasts towards a 200x200 geocast region Data packet (512 bytes) and Control packet (32 bytes) Random waypoint mobility model Performance Metrics Accuracy of geocast delivery Overhead of geocast delivery average number of packets received by each node per geocast average number of bytes received “ “ “ “ “ Performance compared to geocast flooding and LBM Several optimizations are possible to achieve more efficient performance of the basic location-aided routing protocol.

Simulation Results Effect of varying pause time Accuracy of GeoTORA is reasonably high, but not as high as flooding or LBM Local flooding in GeoTORA may not deliver packets to all nodes in the group Delays required to establish a route to the geocast group can be another reason Several optimizations are possible to achieve more efficient performance of the basic location-aided routing protocol. A Z Does not receive geocast C B W Y X

Simulation Results Overhead of geocast delivery The overhead is consistently lower for GeoTORA as compared to the other two protocols The main reason for increasing overhead in GeoTORA is the control packets, not the data packets Several optimizations are possible to achieve more efficient performance of the basic location-aided routing protocol.

Simulation Results Paper also evaluates impact of mobile speed and frequency of geocast Results are similar to previous slides

Conclusions GeoTORA TORA unicast routing is modified for anycasting to nodes in the geocast region Geocasting is achieved by flooding within the region By integrating TORA and flooding, GeoTORA can significantly reduce the geocast overhead However, GeoTORA may provide relatively lower accuracy than flooding and LBM Needs future work

Thank You For more information, contact: Young-Bae Ko (youngko@us.ibm.com) T.J. Watson Research Center, NY, USA Nitin H. Vaidya (vaidya@cs.tamu.edu) Texas A&M University, TX, USA

References [Navas97] J.C. Navas and T. Imielinski, “Geocast-geographic addressing and routing,” MOBICOM’97 [Ko99] Y.-B. Ko and N.H. Vaidya, “Geocasting in mobile ad hoc networks: Location-based multicast algorithms,” IEEE WMCSA’99 [Park97] V.D. Park and M.S. Corson, “A highly adaptive distributed routing algorithm for mobile wireless networks,” INFOCOM’97

Simulation Results Effect of varying moving speed Impact for varying speed can be negligible here, too. Accuracy of geocast delivery Several optimizations are possible to achieve more efficient performance of the basic location-aided routing protocol.

Simulation Results Overhead of geocast delivery Geocast flooding and LBG suffer from a significantly higher overhead than GeoTORA for all moving speed. Several optimizations are possible to achieve more efficient performance of the basic location-aided routing protocol.

Simulation Results Effect of varying geocast frequency Accuracy of geocast delivery Several optimizations are possible to achieve more efficient performance of the basic location-aided routing protocol.

Simulation Results Overhead of geocast delivery For GeoTORA, the overhead due to data packets is almost constant. However, GeoTORA overhead becomes poor for low geocast frequency due to higher control packet overhead to maintain DAGs Several optimizations are possible to achieve more efficient performance of the basic location-aided routing protocol.

TORA – Basic Functions Route Creation: demand driven “query/reply” A query packet (QRY) is flooded through network An update packet (UPD) propagates back if routes exist Route Maintenance: “link-reversal” algorithm React only when necessary Reaction to link failure is localized in scope Route Erasure: A clear packet (CLR) is flooded through network to erase invalid routes

TORA – Conceptual Description B A C E D F G B A C SRC DEST D G E F C B A A C E D F G B D G E F