Abstract
This paper presents a novel efficient receiver design for wireless communication systems that incorporate orthogonal frequency division multiplexing (OFDM) transmission. The proposed receiver does not require channel estimation or equalization to perform coherent data detection. Instead, channel estimation, equalization, and data detection are combined into a single operation, and hence, the detector performs a direct data detector (D <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ). The D <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> is applied to key practical wireless systems such as the Long Term Evolution (LTE) and the New Radio (NR) of the fifthgeneration (5G) system. The performance of the proposed D <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> is thoroughly analyzed theoretically in terms of bit error rate (BER), where closed-form accurate approximations are derived for several cases of interest, and validated by Monte Carlo simulations. Moreover, extensive complexity analysis are performed to evaluate the system suitability for implementation. The obtained theoretical and simulation results demonstrate that the BER of the proposed D3 is only 3 dB away from coherent detectors with perfect knowledge of the channel state information (CSI) in flat and frequency-selective fading channels for a wide range of signal-to-noise ratios (SNRs). If CSI is not known perfectly, then D <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> outperforms the coherent detector substantially, particularly at high SNRs with linear interpolation. The computational complexity of D <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> depends on the length of the sequence to be detected, nevertheless, a significant complexity reduction can be achieved using the Viterbi algorithm.
Highlights
O RTHOGONAL frequency division multiplexing (OFDM) is widely adopted in several wired and wireless communication standards fourth-generation (4G) wireless networks [1], [2], Digital Video Broadcasting (DVB), Terrestrial (DVB-T) and Hand-held (DVB-H) [3], optical wireless communications (OWC) [4], [5], and recently, it has been adopted for the fifthgeneration (5G) New Radio (NR) [6], [7]
OFDM is suitable for frequency-selective channels that are experienced in 4G and 5G wireless systems, and flat fading channels which are commonly experienced in OWC under the effect of atmospheric turbulence [4], [5]
We first assume that constant modulus (CM) constellations such as M -ary phase shift keying (MPSK) is used, we evaluate the complexity for higher-order modulation such as quadrature amplitude modulation (QAM) modulation
Summary
O RTHOGONAL frequency division multiplexing (OFDM) is widely adopted in several wired and wireless communication standards fourth-generation (4G) wireless networks [1], [2], Digital Video Broadcasting (DVB), Terrestrial (DVB-T) and Hand-held (DVB-H) [3], optical wireless communications (OWC) [4], [5], and recently, it has been adopted for the fifthgeneration (5G) New Radio (NR) [6], [7]. Appending the cyclic prefix (CP) prevents intersymbol interference (ISI), and a low-complexity single-tap equalizer can be utilized to eliminate the impact of the multipath fading channel. Under such circumstances, the OFDM demodulation process can be performed once the fading parameters at each subcarrier, commonly denoted as channel state information (CSI), are estimated. The key concept of ACD is to estimate only the amplitude of the channel frequency response and use it for equalization This approach demonstrated to be robust in the presence of phase noise, phase estimation error and frequency offsets, it requires one-dimensional modulation, which may limit its spectral efficiency
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