[a1] | Orthogonal Frequency Division Multiplexing | Discrete Fourier Transform

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  Weighted Cyclic Prefix OFDM: PAPR Analysis and PerformancesComparison with DFTPrecoding  A!stract In this paper, we present a weighted cyclic prefix orthogonal frequency-division multiplexing(WCP-O! # transceiver as a generali$ation of traditional cyclic prefix (CP# - O! % In time-variant channels, this multicarrier transmission scheme may mitigate inter-channel interference(ICI# than&s to the use of non-rectangular pulse shapes% ' precoding step may e required inorder to reduce the pea&-to-average power ratio (P'P)# at the transmitter output% or instance, adiscrete ourier transform (!*# precoder leads to a single carrier transmission scheme withfrequency domain equali$ation% We analy$e the consequences of such a precoding, in terms of  performances, in the context of a time-frequency selective channel% #D$% T$RM&:   WCP-O! ,   CP,   ICI,   P'P),   !*%  '( #TROD)CT O# Cyclic prefix orthogonal frequency-division multiplexing (CP-O! #diagonali$es multipath time-invariant channels if the guard interval is longer than the channel impulse response% 's a consequence, perfect reconstructionmay e otained y means of a single-tap per su-channel equali$er +%urthermore, the fast ourier transform (*# algorithm ensures a low-complexity implementation% .owever, the !oppler spread introduced ytime-variant channels rea&s the orthogonality etween su-channels andinter-carrier interference (ICI# appears% ilter an& ased multicarrier (/ C# systemsoffer a more general transmission framewor&, providing non-rectangular  pulse-shape% *he purpose of this approach is to design matched prototypefilters to time-frequency selective channels in order to yield etter  performance results% !espite attractive performances, / C systems arerarely recommanded in standardi$ed applications ecause of their computational complexity% Indeed, they require the use of polyphase matrixfiltering whose complexity increases with the length of the prototype filters In this wor&, we focus on short prototype filters thatensure a low-complexity implementation% *hus, we consider here the case of filters with the same length as rectangular pulses used in CP-O! % *hedifference with CP-O! is that the pulses do not need to e rectangular%0uch a generali$ation of CP-O! is referred to as weighted cyclic prefix(WCP#- O! % 's a multicarrier transmission scheme, WCP-O! ischaracteri$ed y its high pea&-to-average power ratio (P'P)# which is ama1or drawac& for its hardware implementation% In this study, we compare the P'P) of CP-O! with a time-frequency optimi$ed WCP-O! % We also define a !*- precoding loc& which leads to a single carrier (0C# loc& transmissionscheme with frequency domain equali$ation% We compare the performancesof oth systems with 2!PC channel coding and assuming a time-frequencyselective channel% *(O+,$CT -$:  In time-variant channels, this multicarrier transmission scheme may mitigate inter-channelinterference (ICI# in that we use non-rectangular pulse shapes% ' precoding step may e requiredin order to reduce the pea&-to-average power ratio (P'P)# at the transmitter output% or instance,a discrete ourier transform (!*# precoder leads to a single carrier transmission scheme withfrequency domain equali$ation% We analy$e the consequences of such a precoding, in terms of  performances, in the context of a time-frequency selective channel% .(PRO+/$M D$F # T O# We compare the performances of oth systems with 2!PC channel codingand assuming a time-frequency selective channel% 0( &OFTWAR$ A#D 1ARDWAR$ R$2) R$M$#T&
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