AnImproved PTAMethodtoEstimate theResidual Carrier Frequency Offset inWireless OFDM Systems

Animproved pilot toneaided (PTA)methodto degrades the systemperformance. Therefore, many estimate theresidual frequency offset (RCFO)isproposed for algorithms areproposed totrack theresidual frequency offset. wireless orthogonal frequency division multiplexing (OFDM) Theavailable methodscan be classified intothree systems. Basedontheestimated SNRsofthesubchannels, the cross-correlation~~~~ datbewe adacnOFMsmoso,h categories (91- (121, i.e., pilot toneaided (PTA)method, cyclic cross-correlation data between adjacent OFDM symbols onthe prfx-ae 'CBsceeaddcso-ietd(D sub-channels withhigh quality transmissions areselected, and prefix-based (CPB)schemeanddecision-directed (DD) hardecde. Th hardeiin anddatonthepio'oe scheme. ThePTA approach iSthesimplest method, which harddecided. Theharr decisionsanddataonthepilottoestimates frequency offset byperiodically inserting pilots into areusedtoestimate theresidual frequency offset on the particular subcarriers andcorrelating thereceived symbols corresponding sub-channels respectively. Eachof the withknownsymbols. However, inwireless channel, thegains estimatedl RCFOs iSweighted by theS1NRon the corresponding RCFsu a andc nedb toe im R th RCF ofpilot channels aredifferent duetomulti-path transmission, correstimationdi ng pero ance. Te simuaione rstsiethe that andthelowgains ofthesubchannel greatly degrade the performance oftheresidual frequency offset estimation by theproposed schemeachieves muchbetter performance than PTA method. Literature (10)proposed a weighted PTA theavailable PTAschemes. methodtoestimate theRCFO forwireless OFDM systems