Date of Award


Degree Name

Master of Science


Computer Engineering


Michael P. Mcgarry


The use of intermediary caching routers to service retransmission requests was investigated in this thesis. The main goal is to reduce the expected retransmission delay in a video communication network where the capacity for intermediate caching routers is constrained. In order to reduce the retransmission delay, the effect of the placement of routers with caching ability is investigated. Moreover, as a consequence of reducing the retransmission distance, the energy spent on retransmitting video packets is reduced as well. The average retransmission delay and the average energy consumption were modeled with mathematical programs that select the optimal placement of caching routers to minimize the expected retransmission delay and the expected energy consumption respectively; both mathematical programs are identical in structure and a solution method is developed to solve both programs. An extensive numerical analysis was conducted to measure the performance of the optimal placement. Furthermore, a computer simulation model was developed to validate the results obtained in the numerical analysis. The numerical analysis clearly indicates that the optimal placement of caching routers signicantly reduces the average retransmission delay and the average energy consumption for retransmission, making Automatic Repeat requests (ARQ) a more enticing error recovery technique for video communication over a packet switched network.




Received from ProQuest

File Size

70 pages

File Format


Rights Holder

Jesus Enrique Hernandez