tailieunhanh - Mobil Ad Hoc Networks Protocol Design Part 15

Tham khảo tài liệu 'mobil ad hoc networks protocol design part 15', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 552 Mobile Ad-Hoc Networks Protocol Design A standard AODV request message is 48 bytes and a reply message is 44 bytes. The DITD model uses request message of 60 bytes and reply messages of 56 bytes. Therefore DITD increases the routing control packet size by 12 bytes. DITD s routing control packets contain trust associated variables and flags to trigger back-tracked certificate distribution. The DITD certificate control packets are 508 bytes in size as they included a 450 byte certificate. It is noted that making the routing and certificate control packets separate and independent from each other has a greater impact on reducing the per byte packet overhead. This independency allows for concurrent processing of packets which is optimal in a fully distributive ad hoc network. Jr DITD pausetime 0s Fig. 14. Control packet overhead for highly mobile network 0 second pause time t AODV pausetime 250s A DITD pausetime 250s . Control packet overhead for partially stable network 250 second pause time Trust Establishment in Mobile Ad Hoc Networks Direct Trust Distribution-Performance and Simulation 553 End-to-End Delay The average end-to-end delay results are presented in Figure 16 and Figure 17. It is observed that the DITD model delivers packets with more delay than AODV. The additional delay is attributed to the transmission delay the packet queuing delay and the processing delay of additional certificate control packets. The processing delay includes verification. A conventional certificate distribution scheme that follows the route discovery process would require that certificates be verified before the routing packets are forwarded. DITD performs verifications independent of the routing procedure. The request route is established following the route request message RREQ to the destination and DITD performs verifications independently without hindering the propagation of the RREQ message. -A- DITD pausetime 0s Fig. 16. Average end-to-end delay for highly mobile .