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An Adaptive Timeout Scheme for Short Tcp Flows over 3 G Wireless Networks
| Content Provider | Semantic Scholar |
|---|---|
| Author | Prabhakar, Tadinada Vankata Kuri, Joy |
| Abstract | The focus of this work is on performance enhancement of short-lived TCP flows over a wide-area network with the last hop being a 3G wireless link. We take the 3GPP Non Real Time traffic model and show that when such a short-lived flow encounters a prolonged bad period on the wireless link, the TCP source’s congestion window can become full, causing the source to stall, waiting for ACKs that never arrive. The stalled source then wastes time till the RTO timer expires, causing a timeout. The effect of this is poor TCP throughput. Our work tackles this specific problem by using two mechanisms: (a) a feedback mechanism from the base station back to the TCP source using ICMP messages indicating severe bad periods on the wireless link, and (b) an adaptive mechanism that adjusts the RTO timer value to avoid situations where the source idles unnecessarily. The RTO timer adjustment can lead to either prematureor delayedtimeouts, depending upon the state of the TCP source when the feedback arrives. Simulation results indicate that the proposed timeout mechanism offers over 100% throughput performance improvement even when the bad state is about 50%. The average RTO value is lower with our scheme, the average goodput obtained is 85% even at 50% bad state, and the source idle time is at least 3 times less with our scheme. The scheme performs well also for bulk data traffic. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.mysmu.edu/phdis2010/kartikm.2010/DOCS/ncc147_final.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
