Efficient receiver algorithms for DFT-spread OFDM systems

• Published in: IEEE transactions on wireless communications Vol. 8; no. 6; pp. 3216 - 3225
• Main Authors: Prasad, N., Shuangquan Wang, Xiaodong Wang
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01-06-2009; Institute of Electrical and Electronics Engineers; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Antenna arrays; Applied sciences; Base stations; Decision feedback equalizers; Demodulators; DFT-spread OFDM; Discrete Fourier transforms; Equalization; Equipments and installations; Exact sciences and technology; Filters; Fourier transforms; Gain; Information, signal and communications theory; interference suppression; Inverse; linear filter; log likelihood ratio; MIMO; Mobile radiocommunication systems; Modulators; Multiaccess communication; Multiplexing; OFDM; OFDMA; Orthogonal Frequency Division Multiplexing; Peak to average power ratio; Radiocommunications; Receivers; SDMA; Signal and communications theory; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Transmitters; Transmitters. Receivers; Wireless networks; Performance evaluation; SDMA; Noise reduction; 3G mobile communication; Wireless telecommunication; Peak to average power ratio; Discrete Fourier transformation; Frequency division multiple access; Transmitter; log likelihood ratio; Demodulator; OFDMA; Uplink; Mobile radiocommunication; Modulator; Logarithmic function; Likelihood ratio; Telecommunication standards; Scheduling; Equalization; Computational complexity; DFT-spread OFDM; Interference suppression; Space division multiple access; Algorithm performance; Linear filter; Orthogonal frequency division multiplexing; Signal processing
• ISSN: 1536-1276; 1558-2248
• DOI: 10.1109/TWC.2009.080941

For the 3GPP LTE uplink transmissions, the DFTspread OFDM technique has been adopted as the air interface in order to reduce the peak-to-average-power ratio (PAPR). In this scheme, each data symbol is spread over many tones by a discrete Fourier transform (DFT) operation at the transmitter before being sent to the orthogonal frequency division multiplexing (OFDM) modulator. Moreover, more than one user can be scheduled over the same frequency and time resource block (RB) via space-division multiple-access (SDMA). The conventional receiver technique for such DFT-spread OFDM systems involves tone-by-tone single-tap equalization followed by an inverse DFT operation. In this paper, we propose a more powerful receiver technique for DFT-spread OFDM systems that consists of an efficient linear pre-filter and a two-symbol soft output demodulator. The proposed method can be applied to both single-user per RB (DFT-S-OFDMA) and multiple users per RB (DFT-S-OFDMSDMA) systems and it offers significant performance gains over the conventional method, especially in the high-rate regime, with little attendant increase in computational complexity.