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ABC: A Simple Geographic Forwarding Scheme Capable Of Bypassing Routing Holes In Sensor Networks Presented by: Anita Mohebi Dhruti Joshi Yueh-Shan Shih. CONTENTS. Introducing ABC components Comparing ABC with 2 different schemes :IGF and GPSR in theory
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ABC:A Simple Geographic Forwarding Scheme Capable Of Bypassing Routing Holes In Sensor NetworksPresented by:Anita MohebiDhruti JoshiYueh-Shan Shih
CONTENTS • Introducing ABC components • Comparing ABC with 2 different schemes :IGF and GPSR in theory • Comparing the analytical results of ABC implicit and ABC explicit model with simulation results gained from Glomosim simulator • Conclusion
WHATISABC? ABC (ANGLED RELAING WITH BACKOFF TIME AND RELAY CANCELATION) is a Simple , lightweight and reliable scheme for bypassing the routing holes in a wireless sensor network.
ABC GOAL • Reduce energy consumption by optimizing the bypassing routing holes. It uses the combination of boundary recognition technique and implicit acknowledge to achieve this goal. • Speed up the message delivery rate by reducing the contention and number of retransmissions.
Mechanism of IGF(Implicit Geographic Forwarding ) • Using RTS/CTS mechanism • Which increases the cost at Mac layer specially when the size of data is small. • Using lazy binding conceptorshifting the forwarding area in face of routing holes. • Which increases the average delay due to searching for appropriate nodes for bypassing the data around the holes and also packet overhead in case of large number of holes.
Mechanism of GPSR(Greedy Perimeter Stateless Routing) • Establishing tunnels for bypassing routing holes • Which needs a lot of initial communications. • Combining the greedy forwarding on whole network with perimeter forwarding. • Which suffers from latency and packet loss when states of nodes are changed ,and also it is required to maintain the information of all neighbors.
ABC components : • Angled transmission The source node sends the message with specifying a limited angle and the location information of the source and destination nodes. Then the rest of nodes will decide if they are in the relay zone defined by the angle or not, so they can relay the message. The other nodes outside the zone will disregard the message.
ABC components : • Back off time and relay Cancellation Whenever one node in a zone relays the message ,all nodes in the zone try to relay it .It will be fulfilled according to their back off time ,which depends to their distance to the destination. The node which relays the message ,sends it the same way as the previous sender node using the same angle. All other nodes in the zone will cancel their pending relays.
ABC components : • Implicit ACK The node which relays the message ,sends an implicit acknowledge to the previous sender node .If the source node doesn’t detect any relay process in a time out period ,retransmits the message with a different angle and specifies a different zone.
Implicit ACK di : is a distance of node i to the optimal reception perimeter.
ABC components : • Bypassing Routing Holes It is based on boundary recognition to bypass the routing holes. Each hole node inserts its information into the data packet and continues to forward it. The process will continue until a node receives an acknowledge of relayed message .
Difference between implicit and explicit ACK In implicit ACK if the source node fails to receive the ACK it will retransmit the message through another zone with specifying different angle, however in explicit ,if the node that receives message and sends ACK doesn’t detect any response ,it will relay the message.
Analysis • Average distance in relay zone 1: L: The distance between the source node to destination P :The probability each node can relay the message
Average Hop Count (greedy forwarding phase) • The average distance per hop in greedy forwarding phase: • Average hop count in the greedy forwarding stage : • Lg : distance that a message can be relayed in the greedy forwarding phase
Average Hop Count (bypassing phase) The average distance per hop in bypassing phase: Average hop count in the bypassing phase : Lb : distance that a message can be relayed in the bypassing phase
Average Delay Per Hop • Implicit Scheme : • Explicit Scheme :
Analysis vs. Simulation To compare the analytical results of ABC implicit and ABC explicit with results from simulations of ABC implicit ,ABC explicit ,IGF and GPSR according to different packet sizes different number of sources and destinations, and different number of holes ,the accuracy of the analytic results was evaluated by simulating ABC with one source ,and one destination.1800 nodes were set in 1300 x 1300 square meter network randomly.
Average Delay According To Size Of Packets With 4 Sources Figure (a) shows the average delay in ABC implicit is the smallest .The average delay in ABC explicit is longer than in ABC implicit ,but smaller than in IGF and GPSR.
Average delay according to size of packets with 8 sources Figure (b) shows the average delay for different size of packets when we have 8 sources. Again the average delay in ABC implicit is the smallest.
Delivery Ratio with 4 sources This figure shows delivery ratio in ABC implicit is a little lower than that in IGF but higher than in ABC explicit and GPSR. The reason is IGF uses RTS/CTS protocol ,which reserves the channel around the transmission areas before sending a message. It increases the delivery ratio.
Delivery Ratio with 8 sources This figure shows the delivery ratio for 8 sources. The result is the same as the last figure :the delivery ratio in ABC implicit is lower than in IGF.
Number of Transmissions Per Message Delivery With 4 Sources This figure shows the number of transmissions per message delivery in ABC Implicit is higher than that in ABC explicit ,but lower than those in IGF and GPSR.
Number of Transmissions Per Message Delivery With 8 Sources This figure shows the same performance as the transmissions per message deliveryfor 4 sources. The result is the same as the last figure: implicit is higher in transmissions than explicit but lower than GPSR and IGF.
Average Delay According to Size Of Routing Holes With 4 Sources This figure shows the average delay in ABC explicit is longer than in ABC implicit and smaller than those in IGF and GPSR ,so when the size of routing holes increases ,ABC implicit and ABC explicit surplus IGF and GPSR.
Delivery Ratio According To Size of Routing Holes With 4 Sources This figure shows that delivery ratio in ABC implicit is a little lower than in IGF but higher than in ABC explicit .There is a little difference between the 3 schemes (IGF ,GPSR and ABC explicit) when the size of routing holes increases.
Number Of Transmission According To Size Of Routing Holes With 4 Sources This figure shows the number of transmission in ABC implicit is higher than in ABC explicit ,but lower than in IGF and GPSR. Also the difference in all of them gets larger when the size of routing holes increases.
Conclusion In all figures ,ABC implicit and ABC explicit show better feedback in terms of average delay and number of transmissions per message delivery when the size of the routing hole is larger . In terms of delivery ratio ,GPSR underperforms all ,but IGF outperforms ABC implicit and ABC explicit ,but the difference is slight.
Conclusion ABC has two major characteristics : • Using Implicit ACK ,which combines the Mac and forwarding features . • An efficient bypassing routing holes As per analysis and simulation results ,we can consider ABC as an efficient feature to approach low delay and packet overhead per message delivery ,which will result in low energy consumption in wireless sensor networks. Moreover, in terms of delivery ratio ABC is reliable.
