Perormnance Improvement of a High Mobility VehicularCo:mmunication Systemn UsingFuzy- DecisionViterbi Decoder
Data Scrambler · 2006
A fuzzy-decision Viterbi decoder isproposed fora dedicated short-range communications (DSRC)system tocombat theeffect ofatime-varying fading channel. Theperformance ofthe DSRCsystem using theproposed fuzzy -decision Viterbi decoder is compared withboththehard-decision andsoft-decision Viterbi decoder. Thesimulation results showthatthegaininperformance oftheproposed fuzzy-decision Viterbi decoder withrespect tothe hard-decision andsoft-decision Viterbi decoder issignificantly increased. Ke Words -DSRC,fuzzy-decision Viterbi decoder, time-varying fading channel, frequency synchronizer I INTRODUCTION Dedicated short-range commnunications (DSRC)system provides wireless conumnications overshort distance between theroadside andhigh-speed mobile radio units orbetween high- speed vehlicles. InIEEE8O2. lipstandard (1)J IEEE802. 11and 802.1 laaremodified asamediumaccess control (MAC)and physical layer (PHY)specifications, respectively. TheDSRC system vwill operate inamobile environment exhibiting tiine varying characteristics. Thetime-varying fading effect ofthe DSRCsystem maynotbeeffectively compensated byusing the longsymbol training andpilot-based freqnency synlchroniizer (2). Thecombined interleaving andconvolution coding provides the frequency diversity fnnction generated bythewideband natre of theDSRCsystem. Thepunctnring convolution code(3)oniy needs oneencoder/decoder togenerate eight different coding rates fortheDSRCsystem. Inthis paper, Wefocus onthestndy ofchannlcoding scheLmes inorder tofurther improve its perfonrance inthetimevarying environment. Theiinproxvemenit inperformance oftheDSRCsystem achieved byreplacing the harddecision andsoftdecision Viterbi decoder withthe proposed fuzzy decision Viterbi decoder will bevalidated with simulations.