Frequency-domain subcarrier diversity receiver for discrete Hartley transform OFDM systems

Abstract

In recent years, there has been an increasing interest in the use of the discrete Hartley transform (DHT) for orthogonal frequency-division multiplexing (OFDM). Previous studies have not reported an improvement in bit error rate (BER) when using a DHT-based OFDM without substantial complexity increase due to the fact that the DHT cannot diagonalize a circulant channel matrix but rather produces a unique structured matrix that has only a main diagonal and anti-diagonal. In this paper, the coupling between symmetric carriers is exploited by introducing a frequency-domain subcarrier diversity receiver for DHT-based OFDM systems. The proposed simple receiver structure takes advantage of the coupling to enhance the BER performance of the DHT-OFDM system by increasing the diversity gain between subcarriers. A detailed statistical and performance analysis of the system is presented, in which closed-form expressions of the average BER were derived. The proposed system performance was compared to the conventional discrete Fourier transform OFDM (DFT-OFDM), the generalized DHT-OFDM, and the DHT-precoded OFDM systems in terms of average BER and peak-to-average power ratio (PAPR). The proposed DHT-OFDM system outperforms the generalized DHT-OFDM system by 12 dB and outperforms the conventional DFT-OFDM and the DHT-precoded OFDM systems by 17 dB at an average BER of 10 −5. In terms of PAPR, the proposed DHT-OFDM system suffers from an approximately 5.5, 2, and 1 dB increase in PAPR when compared to the DHT-precoded OFDM, the conventional DFT-OFDM, and the generalized DHT-OFDM systems, respectively.

On the Fast DHT Precoding of OFDM Signals over Frequency-Selective Fading Channels for Wireless Applications

“…It is known that DFT-s-OFDM [6], an example of SC scheme, can provide 3-5 dB better output power than OFDM due to low-PAPR transmission schemes with low modulation orders [3]. Other studies have explored the use of DHT as an alternative kernel for DFT in multi-carrier system design with improved PAPR and BER performances [27]. A major limitation of such proposal is that DHT kernel applies to real-signals; however, DFT spans both real and complex signals [23,28].…”

Pulse shaping methods for inter carrier interference reduction in OFDM system

“…So that the use of pulse shaping can reduce ICI power due to the frequency offset [20]. The pulse function in the frequency domain was used in this paper as follows [3]. − REC pulse…”

“…The purpose of using pulse shaping method is to eliminate side lobes that can potentially generate ICI power. The use of ISP pulse can reduce ICI power from the side lobe better than the REC pulse [3].…”

“…OFDM is a multicarrier transmission technique which between subcarriers are arranged to be mutually overlapping and arranged in such a way so that between subcarriers will have orthogonal properties [1,2]. By using this overlapping technique, OFDM systems offer high bandwidth efficiency that save up to 50% [3]. It also has high data rate transmission capability and robust to multipath fading and delay.…”

Generalized Orthogonal Discrete W Transform and Its Fast Algorithm

“…ese transforms have been widely used in communication and signal processing [21][22][23][24][25][26][27][28][29][30]. Numerous approaches on fast algorithms for discrete Hartley-type transforms have been reported [31][32][33][34].…”