Time domain cyclic-selective mapping for PAPR reduction using delayed correlation with matched filter in OFDM system

Abstract

The cyclic-SLM which implements delayed correlation with a matched filter (DC-MF) is proposed in this paper. The cyclic-SLM reduces a peak-to-average power ratio (PAPR) on an orthogonal frequency divison multiplexing (OFDM) signal. This scheme combines the original OFDM signal and its cyclic shifted ones. However, it needs side information (SI) of the cyclic shifts to recover the original signal that decreases the throughput of a wireless OFDM system. The DC-MF estimates the amount of a shift in a receiver side by multipling a recieved signal with its conjugates of the guard interval (GI) sequence in the time domain . Numerical results obtained through computer simulation show that the cyclic-SLM with the DC-MF significantly reduces the PAPR by around 2.5 dB as compared to the original signal. It also achieves the accuracy rate of the amount of the shift close to 100 % and the BER of 10 −4 at E b /N0 = 8.8 dB that is close to the perfect shift estimation.

PAPR Reduction in DCO-OFDM Visible Light Communication Systems Using Optimized Odd and Even Sequences Combination

“…where 0 < α ≤ 1 is a linear factor and τ In the CYSLM scheme [21], the uth candidate signal is constructed by combining the original signal x[n] with D cyclic shift equivalents under the phase shift, given by…”

“…However, these methods have high computational complexity because they require multiple inverse fast Fourier transform (IFFT) operations to construct candidates. Although numerous low-complexity PAPR reduction schemes have been developed, they may not be suitable for VLC systems because the VLC signal is real and positive [16]- [21]. Two similar methods, namely, low-complexity selected mapping (LCSLM) [19] and cyclic selected mapping (CYSLM) [21], were developed for RF-OFDM systems, but both schemes suffer problems, for instance, the resultant frequency-domain phase sequences of the LCSLM and CYSLM schemes have an unequal magnitude, thereby causing degradation in BER performance.…”

Estimation of Cyclic Shift with Delayed Correlation and Matched Filtering in Time Domain Cyclic-SLM for PAPR Reduction

“…The block diagram of the TDC-SLM scheme is shown in Figure 1. The cyclically shifted signal in the TDC-SLM is given as$\begin{array}{c}T3x_f\left[n,{\mathrm{\Delta }}_d\right]\\ =\left\{\begin{array}{cc}x\left(N-{\mathrm{normal\Delta }}_d+n\right),\hfill & -N_{\mathrm{normalG}\mathrm{normalI}}\le n\le {\mathrm{normal\Delta }}_d-\mathrm{normal1},\hfill \\ x\left(n-{\mathrm{normal\Delta }}_d\right),\hfill & {\mathrm{normal\Delta }}_d\le n\le N-\mathrm{normal1},\hfill \end{array}\right.\end{array}$where x [ n ] is the OFDM signal in the time domain at the time index of n , N GI is the GI length, x f [ n , Δ d ] is the SC that is generated by cyclically shifting the OFDM signal by Δ d , Δ d is the amount of the cyclic shift for the d th SC, and Δ d ∈ { Cδ }, where C is an integer [11, 12]. The resolution of the cyclic shifts, δ , has to be large enough for accurate estimation of the cyclic shifts in a receiver.…”

“…Nevertheless, there is a tradeoff between the amount of PAPR reduction and the BER. The method in [12] has been proposed to further reduce the PAPR of the abovementioned scheme. It uses matched filtering (MF) with a Barker sequence to estimate the amounts of cyclic shifts.…”

“…However, multipath components still deteriorate the accuracy rate of cyclic shift estimation since they generate additional peaks at the outputs of the DC-MF. By using the proposed scheme, the accuracy rate then improves and the bit error rate (BER) reduces as compared to that of the conventional TDC-SLM and DC-MF in [12]. …”