论文部分内容阅读
Abstract: The Partial Transmit Sequence (PTS) method with low computation complexity, called decomposition PTS sub-blocking was proposed which employs the radix-2 Inverse Fast Fourier Transform (IFFT) for the signals at the middle stages of an N-point radix-2 IFFT and Decimation In Frequency (DIF) domain. This method (DIF-PTS) can reduce the computation complexity relatively with keeping the same Peak to Averaged Power Ratio (PAPR) performance as that for the conventional PTS techniques. To improve the computation complexity further for the PTS method, the Split-Radix Inverse Fast Fourier Transform (SRIFFT) which can reduce the number of complex computation was proposed. However, the PAPR reduction performance is the same as that for the radix-2 method. In this paper, the authors propose a new weighting factor technique in conjunction with DIF-PTS sub-blocking based on Split-Radix IFFT technique called Improve PTS (I-PTS) which can improve both the PAPR performance and computation complexity without any increasing of side information. This paper presents the various computer simulation results to verifier the effectiveness of proposed method.
Key words: DIF-IFFT (decimation in frequency-inverse fast Fourier transform), PAPR (peak to averaged power ratio), SRIFFT(split-radix inverse fast Fourier transform), PTS (partial transmit sequence).
1. Introduction
The Orthogonal Frequency Division Multiplexing(OFDM) technique has been received a lot of attentions especially in the field of wireless communications because of its efficient usage of frequency bandwidth and robustness to the multi-path fading. From these advantages, the OFDM technique has already been adopted as the standard transmission techniques in the Wireless Local Area Network (WLAN) systems and the next generation of mobile communications systems. One of the limitations of using OFDM technique is the larger Peak to Averaged Power Ratio (PAPR) of its time domain signal. The higher PAPR leads the fatal degradation of OFDM performance in the nonlinear power amplifier located at the transmitter [1].
Partial Transmit Sequence (PTS) method [2] is proposed as one of the distortion-less PAPR reduction methods. However, the computation complexity and the size of side information would increase as increasing the number of clusters and weighting factors. To reduce this computation complexity, DIF-PTS(Decimation in Frequency-PTS) method [3] was proposed in which the intermediate signals are employed within the IFFT and used the radix-2 Decimation In Frequency domain (DIF) to obtain the PTS sub-blocks. Multiple IFFTs are then applied to the remaining stages. The PTS sub-blocking is performed in the middle stages of the N-point radix FFT DIF algorithm. The DIF-PTS method can reduce the computational complexity relatively while it shows almost the same PAPR reduction performance as that of the conventional PTS OFDM scheme.
In this paper, the authors propose a new weighting factor technique for the PTS method in conjunction with DIF-PTS sub-blocking based on the Split-Radix IFFT technique which can improve both the PAPR performance and computation complexity. The proposed method can achieve the better PAPR reduction performance than that for the DIF-PTS method without any increasing of the size of side information.
In the next section, the PAPR problem and conventional PTS are reviewed briefly. Section 3 presents the PTS-based Split-radix technique and section 4 presents the proposed method. Section 5 presents various computer simulation results to verify the effectiveness of the proposed method as comparing with the conventional PTS method. Some conclusions are given in section 6.
References
[1] D. Dardari, V. Tralli, A. Vaccari, A theoretical characterization of nonlinear distortion effects in OFDM systems, IEEE Trans. on Comm. 48 (10) (2000) 1755-1764.
[2] S.H. Muller, J.B. Huber, A novel peak power reduction scheme for OFDM, in: Proc. of the 8th IEEE Int. Symp. on Pers., Indoor and Mobile Radio Commun., September 1997, pp. 1090-1094.
[3] A. Ghassemi, T.A. Gulliver, A low-complexity PTS-based radix FFT method for PAPR reduction in OFDM systems, IEEE Transactions on Signal Processing 56 (3) (2008) 1161-1166.
[4] C. Tellambura, Computation of the continuous-time PAR of an OFDM signal with BPSK subcarriers, IEEE Comm. Lett. 5 (5) (2001) 185-187.
[5] J. Tellado, Multicarrier Modulation with Low PAR, Kluwer Academic Publishiers, 2000.
[6] P. Duhamel, Implementation of “Split-radix” FFT algorithms for complex, real, and real-symmetric data, IEEE Trans. on Acoustics, Speech, and Signal Processing 34 (2) (1986) 285-295.
[7] C. Tellambura, Improved phase factor computation for the PAR reduction of an OFDM signal using PTS, IEEE Comm. Lett. 5 (4) (2001) 135-137.
[8] T. Mata, P. Boonsrimuang, P. Boonsrimuang, H. Kobayashi, Proposal of improved PTS method for STBC MIMO-OFDM systems, IEICE Transactions on Communications E93-B (10) (2010)2673-2676.
Key words: DIF-IFFT (decimation in frequency-inverse fast Fourier transform), PAPR (peak to averaged power ratio), SRIFFT(split-radix inverse fast Fourier transform), PTS (partial transmit sequence).
1. Introduction
The Orthogonal Frequency Division Multiplexing(OFDM) technique has been received a lot of attentions especially in the field of wireless communications because of its efficient usage of frequency bandwidth and robustness to the multi-path fading. From these advantages, the OFDM technique has already been adopted as the standard transmission techniques in the Wireless Local Area Network (WLAN) systems and the next generation of mobile communications systems. One of the limitations of using OFDM technique is the larger Peak to Averaged Power Ratio (PAPR) of its time domain signal. The higher PAPR leads the fatal degradation of OFDM performance in the nonlinear power amplifier located at the transmitter [1].
Partial Transmit Sequence (PTS) method [2] is proposed as one of the distortion-less PAPR reduction methods. However, the computation complexity and the size of side information would increase as increasing the number of clusters and weighting factors. To reduce this computation complexity, DIF-PTS(Decimation in Frequency-PTS) method [3] was proposed in which the intermediate signals are employed within the IFFT and used the radix-2 Decimation In Frequency domain (DIF) to obtain the PTS sub-blocks. Multiple IFFTs are then applied to the remaining stages. The PTS sub-blocking is performed in the middle stages of the N-point radix FFT DIF algorithm. The DIF-PTS method can reduce the computational complexity relatively while it shows almost the same PAPR reduction performance as that of the conventional PTS OFDM scheme.
In this paper, the authors propose a new weighting factor technique for the PTS method in conjunction with DIF-PTS sub-blocking based on the Split-Radix IFFT technique which can improve both the PAPR performance and computation complexity. The proposed method can achieve the better PAPR reduction performance than that for the DIF-PTS method without any increasing of the size of side information.
In the next section, the PAPR problem and conventional PTS are reviewed briefly. Section 3 presents the PTS-based Split-radix technique and section 4 presents the proposed method. Section 5 presents various computer simulation results to verify the effectiveness of the proposed method as comparing with the conventional PTS method. Some conclusions are given in section 6.
References
[1] D. Dardari, V. Tralli, A. Vaccari, A theoretical characterization of nonlinear distortion effects in OFDM systems, IEEE Trans. on Comm. 48 (10) (2000) 1755-1764.
[2] S.H. Muller, J.B. Huber, A novel peak power reduction scheme for OFDM, in: Proc. of the 8th IEEE Int. Symp. on Pers., Indoor and Mobile Radio Commun., September 1997, pp. 1090-1094.
[3] A. Ghassemi, T.A. Gulliver, A low-complexity PTS-based radix FFT method for PAPR reduction in OFDM systems, IEEE Transactions on Signal Processing 56 (3) (2008) 1161-1166.
[4] C. Tellambura, Computation of the continuous-time PAR of an OFDM signal with BPSK subcarriers, IEEE Comm. Lett. 5 (5) (2001) 185-187.
[5] J. Tellado, Multicarrier Modulation with Low PAR, Kluwer Academic Publishiers, 2000.
[6] P. Duhamel, Implementation of “Split-radix” FFT algorithms for complex, real, and real-symmetric data, IEEE Trans. on Acoustics, Speech, and Signal Processing 34 (2) (1986) 285-295.
[7] C. Tellambura, Improved phase factor computation for the PAR reduction of an OFDM signal using PTS, IEEE Comm. Lett. 5 (4) (2001) 135-137.
[8] T. Mata, P. Boonsrimuang, P. Boonsrimuang, H. Kobayashi, Proposal of improved PTS method for STBC MIMO-OFDM systems, IEICE Transactions on Communications E93-B (10) (2010)2673-2676.