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A non-orthogonal multicarrier signal, termed spectrally efficient frequency division multiplexing (SEFDM), is investigated in this work. It improves spectral efficiency by compressing sub-carrier spacing below the symbol rate at the cost of self-created inter carrier interference (ICI). Sphere decoding (SD) is an efficient method to recover signals approaching maximum likelihood (ML) performance....
In this paper, an enhanced scheme of Index Modulation for Orthogonal Frequency Division Multiplexing (IM-OFDM), called Repeated IM-OFDM with Diversity Reception (ReIM-OFDM) is proposed. ReIM-OFDM achieves performance improvement over the convetional IM-OFDM at the same spectral efficiency by providing additional space and frequency diversity. Similar to IM-OFDM, the proposed ReIM-OFDM also activates...
In next generation communication systems high data rate, and higher transmission capacity through wireless channel are important for researchers. Filter bank based multicarrier (FBMC) modulation with offset quadrature amplitude modulation (OQAM) makes researchers interested due to its advantages over orthogonal frequency division multiplexing (OFDM). The paper indicates that OFDM, FBMC-QAM, multiple-input...
Multiuser Detection (MUD) and Channel Estimation techniques in Space-Division Multiple Access aided Orthogonal Frequency Division Multiplexing (SDMA-OFDM) systems recently received intensive interest in receiver design technologies. The maximum likelihood (ML) MUD that provides optimal performance has the cost of a dramatically increased computational complexity. The minimum mean-squared error (MMSE)...
A novel joint detector is proposed for the quadrature amplitude modulation (QAM) filter-bank multicarrier (FBMC) system with the prototype filter of the conventional FBMC. Based on the inter-carrier-correlation (ICC) matrices, the intrinsic interference model of the QAM FBMC is derived. The total interference can be divided into inter-carrier interference (ICI) and inter-symbol interference (ISI)...
This paper presents a computationally efficient cyclostationarity detection based spectrum sensing in cognitive radio. Traditionally, several cyclostationarity detection based spectrum sensing techniques with a low computational complexity have been presented, e.g., peak detector (PD) or maximum cyclic autocorrelation selection (MCAS), and so on. Compared to both techniques, PD can be affected the...
In this paper, a novel pilot-aided algorithm is proposed for the detection of integer frequency offset (IFO) in orthogonal frequency division multiplexing (OFDM) systems. By transforming the IFO into two new integer parameters, the proposed method can largely reduce the number of trial values for the true IFO. The two new integer parameters are detected using two different pilot sequences, a periodic...
The existing solutions for multi-user detection in uplink (UL) grant-free sparse code multiple access (SCMA) rely on the prior knowledge of user sparsity, i.e., the number of active users. An alternative solution, which sets the sparsity as a statistically empirical value to get a rough active user set and then eliminates the false detected inactive users with joint message passing algorithm (JMPA),...
Multiple-input multiple-output orthogonal frequency division multiplexing with index modulation (MIMO-OFDM-IM), which provides a flexible trade-off between spectral efficiency and error performance, is recently proposed as a promising transmission technique for energy-efficient 5G wireless communication systems. However, due to the dependence of subcarrier symbols within each subblock and the strong...
We consider index modulation (IM) for single-carrier (SC) systems in this paper. Compared with conventional orthogonal frequency division multiplexing (OFDM) IM, the resulting approach, which is referred to as SCIM, has a better performance due to the path diversity gain under a multipath fading environment. For sparse IM, since compressive sensing (CS) algorithms can be used for low-complexity signal...
The paper introduces an OFDM signal detector based on cyclic correlation function. The detector belongs to the class of blind SCD detectors. The paper presents the main relations connected with the idea of cyclostationarity and cyclostationary features of OFDM signals. Results of simulations are presented as well.
In this paper, we address the problem of signal detection in multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) system by using auto-encoder (AE) network and extreme learning machine (ELM). The existing signal detection algorithms, such as zero-forcing successive-interference-cancellation (ZF-SIC), minimum-mean-square-error successive-interference-cancellation...
The performance of a low-complexity detection technique for OFDM-IM over the Nakagami-m fading channel has been analyzed. The orthogonal frequency-division multiplexing with index modulation (OFDM-IM) has recently been used in conjunction with the subcarriers using on-off keying modulation. The result shows improved performance in comparison with the conventional OFDM. The closed-form expression for...
In order to assist dynamic spectrum access in the cognitive radio framework, a precise real-time identification of the signals sent by either the primary or secondary users should be necessary. Orthogonal frequency-division multiplexing (OFDM) signals with and without DFT precoding are commonly adopted in the recent wireless communications standards. Therefore, the accurate classification of such...
Orthogonal frequency division multiplexing (OFDM) has been identified as a potential method to enhance the performance of wireless communication links degraded by cosite interference, impulsive noise and frequency selective fading. In this paper, an OFDM software defined radio (SDR) receiver based on a wideband substrate integrated waveguide (SIW) six-port circuit is described and analyzed. A six-port...
Multiple input multiple output orthogonal frequency division multiplexing (MIMO-OFDM) is known as a high capacity system for data transmission over broadband wireless communication channels. However, the time-varying fading and Doppler effect of the underwater acoustic channel can destroy the orthogonality of subcarriers, causing intercarrier interference (ICI). In this paper, we proposed a combined...
Ambient backscatter communications (AmBC) enables radio-frequency (RF) powered devices (e.g., tags, sensors) to modulate their information bits over ambient RF carriers in an over-the-air manner. This system, called ``modulation in the air'', thus has emerged as a promising technology for green communications and future Internet-of-Things. This paper studies the AmBC system over ambient orthogonal...
As we know, Cognitive Radio comes to improve the underutilization problem of available radio spectrum by using one of its functional called spectrum sensing. In this paper, we compare two methods between Fixed Sample Size Test and Sequential Detection specifically for spectrum sensing using OFDM signals with Gaussian noise. The compared parameter in this simulation is OFDM Average Block (AVB) which...
One of the major components of cognitive radio is its ability to detect the availability of unused spectrum. Detection for the presence or absence of the spectrum hole plays a very important role before the frequency spectrum is used. Previous research in the field of spectrum detection for cognitive radio has been done for the distributed detection using energy detector with 2-bit decision but its...
Inspired by the success of multi-carrier waveforms such as Orthogonal Frequency Division Multiplexing (OFDM) in radio communication, multi-carrier based radar waveform designs have gained strong interest recently. Reasons for this include their resistance to multipath fading, ability to overcome the limitations of a congested frequency spectrum, ability to exploit frequency diversity gains, and potential...
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