To appear in IEEE Transactions on Wireless Communication, submitted January 2011, revised August 2011, accepted November 2011.
Wireless communication networks use link adaptation to select physical layer parameters that optimize the transmission strategy as a function of the wireless channel realization. In the vehicle-to-vehicle (V2V) networks considered in this letter, the short coherence time of the wireless channel makes link adaptation based on the impulse response challenging. Consequently, link adaptation in V2V wireless networks may instead exploit the large-scale characteristics of the wireless channel (i.e. path loss) since they evolve slowly and enable less frequent feedback. Large-scale channel information may be captured through channel or position/motion measurements. In this letter, through the definition of new large-scale coherence expressions, we show that channel measurements render large-scale coherence as a function of time-change while the position/motion measurements render coherence as a function of velocity-change. Highway simulations with modeled and measured channels demonstrate the advantage of position/motion information for feedback reduction in V2V link adaptation.
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