TCP-Cognizant Adaptive Fonvard Error Correction in Wireless Networks

A b s l r n b Wtmlpu Links LR thamctetkd by high bit ermr rates and Intermittent connectivity. Thi. can result In rignilant dwrdntion In the performance (goodput) of TCP over wireless nohvorks since noncongestion related packet IOSICI can be misinterpreted by TCP sli indications of network congation, resulting la unnecasaq' congestion contml. In this paper, we pmpore a technique, TCP with adaptive forvtard ermr cormtion (TCP-AFEC), to impmve TCP prrfomsnce over wirelanr networks. TCP-AFEC combines the veU-stablishad perfomance characterhition of TCP with an undentsndiog of the link layer enmi conml scheme to dynamiedly select the fomrrd ermr c o m t i o n (FISC) that mnrimi2es TCP gwdpot according to the eumnt channel condition. The benefit of coupling a rhancteri2stion of TCP performance with link layer FEC to impmve TCP gwdput b demonstnted by eompsrlng the performance of TCP-AFEC against those of TCP-SACK and Snoop. Sirnolntian mui t s show that TCP-AFEC outperfannr TCPSACK and Snoop for a wide range ofwimlerr c h a " conditions. effect of adding FEC to TCP packets between the base station and mobile host on TCP goodput and present an algorithm to select the code to be used for a given channel condition. The benefit of combining TCP performance characterization with link layer FEC to improving TCP goodput over wireless networks is demonstrated through comparison with several other proposals. We show that TCP combined with adaptive FEC, TCP-AFEC, significantly improvesTCP performance over TCP-SACK across a wide range of wireless channel conditions. We also compare TCP-AFEC with Snoop [5 ] , a proposal that provides the biggest improvement over TCP Reno of all approaches under study in [I]. Our simulation results show that TCP-AFEC achieves a goodput comparable to that of Snoop at low bit errors rates and considerably higher goodputthan Snoop when bit error rates are high, and thus is more robust than Snoop -