Coordinate Interleaving Research Articles

Generalized Coordinate Interleaving Media-Based Modulation

In this letter, a new generalized coordinate interleaving media-based modulation (GCI-MBM) scheme for MIMO system is proposed. In this scheme, the coordinate interleaved orthogonal design, precoding matrix, generalized spatial modulation structure are combined with MBM principle. Thus, the proposed scheme not only achieves the second-order transmit diversity but also improves the spectral efficiency. Furthermore, to reduce decoding complexity, a low-complexity ordered fast sphere decoding (OF-SD) algorithm is proposed. Theoretical performance analysis and simulation results show that the GCI-MBM scheme outperforms some existing MBM schemes in terms of the bit error rate (BER) performance.

Rectangular Differential OFDM With Index Modulation Using Coordinate Interleaving

Differential subcarrier index modulation (DSIM) is an emerging OFDM with index modulation (OFDM-IM) technique, which does not require channel state information (CSI) at the receiver. However, the DSIM scheme has two drawbacks of lower spectral efficiency and lacking transmit diversity. In this letter, by combining rectangular differential coding and coordinate interleaving orthogonal design, a novel rectangular differential OFDM-IM using coordinate interleaving (CI-OFDM-RDIM) scheme is proposed. In this scheme, the dispersion matrix is projected to a dispersion vector that is transmitted in a single symbol interval, so that CI-OFDM-RDIM improves spectral efficiency compared with DSIM. Since the symbols in two adjacent differential groups are interleaved, the proposed scheme obtains diversity gain. Furthermore, owing to the orthogonality of its processing matrix, a low-complexity decoupled maximum likelihood (D-ML) detector is proposed. Theoretical performance analysis and simulation results show that CI-OFDM-RDIM outperforms DSIM in terms of the bit error rate (BER) performance.

Repeated Index Modulation-OFDM With Coordinate Interleaving: Performance Optimization and Low-Complexity Detectors

This article investigates performance of an advanced scheme of index modulation for orthogonal frequency division multiplexing (IM-OFDM), called the repeated index modulation-OFDM with coordinate interleaving (RIM-OFDM-CI), which achieves higher transmission reliability than the conventional IM-OFDM with coordinate interleaving (IM-OFDM-CI). We first derive the approximated expressions for the symbol error probability (SEP) of RIM-OFDM-CI. The obtained SEP provides an insight into the impact of system parameters on the error performance, which allows for selection of an optimum constellation rotation angle to minimize SEP. Two enhanced detectors, namely, the log likelihood ratio (LLR) and greedy detector for RIM-OFDM-CI are proposed. The proposed detectors not only achieve nearly same performance as the maximum likelihood detector but also significantly reduce detection complexity of the RIM-OFDM-CI system. Simulation results are reported to validate advantages of the proposed RIM-OFDM-CI and low-complexity detectors against benchmarks.

Low-Complexity MIMO MMSE Receiver with Performance Enhancement via Coordinate Interleaving

Multiple-input multiple-output (MIMO) Minimum mean-square error (MMSE) receivers are widely adopted in the latest communication standards and reducing the complexity of these receivers while preserving the error performance is highly desirable. In this work, we study the error performance and implementation complexity of MIMO MMSE receivers when combined with a coordinate interleaved signal space diversity (SSD) technique. Contrary to the well-known trade-off between the error performance and implementation complexity, the proposed system leads to a considerably simplified MIMO MMSE receiver with significant performance gains when compared to the original MIMO MMSE receiver. Unlike the standard MIMO MMSE receiver, the proposed coordinate interleaved technique induces a block diagonal transmit correlation matrix providing both performance enhancement and complexity reduction. The results show that the error performance can be improved more than 10[Formula: see text]dB with up to 71% computational complexity reduction. The complexity comparison between the original and proposed approaches is also verified by means of field-programmable gate array (FPGA) implementation.

Quadrature NOMA: A Low-Complexity Multiple Access Technique With Coordinate Interleaving

In this letter, we offer a low-complexity multiple access method based on coordinate interleaving coined as quadrature non-orthogonal multiple access (NOMA). It is shown that by properly utilizing two quadrature carriers, both error performance enhancement and reduction in the number of successive interference cancellation (SIC) operations can be attained as compared to the standard power-domain NOMA approach. Specifically, in a $K$ -user network with single-antenna nodes, the reduction in the number of SIC operations is more than 50% as compared to the original NOMA scheme. When $K=2$ , the power gain obtained by the inspected technique can be as large as 2.5 dB without resorting to any SIC process at all. Further, as compared to the original NOMA idea, the considered approach requires fewer number of SIC stability conditions on power allocation and functions for any power allocation strategy (without an error floor) when $K=2$ . Some similar gains are also applicable for $K>2$ . The decrease in the number of SIC operations manifests itself by boosting the immunity of the system against possible failures during the SIC process.

Modified CI and Modulation Order Replacement for Enhancing OFDM-IM Performance

Recently, a lower order modulation aided bit error rate reduction scheme was proposed for orthogonal frequency division multiplexing with index modulation (OFDM-IM). Here, the key idea was to replace the conventional modulation order in OFDM-IM with a lower order modulation and its rotated versions. In this paper, we incorporate on the aforementioned system, a novel coordinate interleaving (CI) scheme, where instead of the conventional application of CI to the data symbols alone, it is applied to the entire sub-block containing data symbols and zero-padded sub-carriers. Also, we replace the conventional modulation order in OFDM-IM with a higher order signal constellation. This leads to an increase in the number of symbol selecting bits and a subsequent decrease in the number of index combinations required for mapping. Next, the resulting excess inactive sub-carriers are used to carry more copies of the same data symbols in order to provide diversity. Finally, this modulation order replacement scheme is extended to the in-phase quadrature variant of OFDM-IM. Numerical results indicate that up to 7-dB transmit power gains over OFDM-IM and also over the existing lower order constellation aided scheme can be accrued.

Performance Analysis of Repeated Index Modulation with Coordinate Interleaving over Nakagami-m Fading Channel

In this paper, a new Space-Time Block Coded Spatial Modulation (SM) scheme based on the Golden Code, called the In this paper, we evaluate the symbol error performance of an extended Index Modulation for Orthogonal Frequency Division Multiplexing (IM-OFDM), namely repeated index modulation-OFDM with coordinated interleaving (abbreviated as ReCI), over the Nakagami-m fading channel. The ReCI system attains higher error performance than the conventional IM-OFDM with coordinate interleaving (IMOFDM-CI). In order to investigate the system performance over the Nakagami-m fading channel, we derive the closed-form expressions for the symbol error probability (SEP) and the bit error probability (BEP). The analytical results give interesting insights into the dependence of SEP on system parameters. Their tightness is also validated by numerical results, which show that our proposed scheme can provide considerably better error performance than the conventional IM-OFDM and IM-OFDM-CI at the same spectral efficiency. DOI: 10.32913/mic-ict-research.v2019.n1.863

Performance Analysis of Repeated Index Modulation with Coordinate Interleaving over Nakagami-m Fading Channel

In this paper, a new Space-Time Block Coded Spatial Modulation (SM) scheme based on the Golden Code, called the In this paper, we evaluate the symbol error performance of an extended Index Modulation for Orthogonal Frequency Division Multiplexing (IM-OFDM), namely repeated index modulation-OFDM with coordinated interleaving (abbreviated as ReCI), over the Nakagami-m fading channel. The ReCI system attains higher error performance than the conventional IM-OFDM with coordinate interleaving (IMOFDM-CI). In order to investigate the system performance over the Nakagami-m fading channel, we derive the closed-form expressions for the symbol error probability (SEP) and the bit error probability (BEP). The analytical results give interesting insights into the dependence of SEP on system parameters. Their tightness is also validated by numerical results, which show that our proposed scheme can provide considerably better error performance than the conventional IM-OFDM and IM-OFDM-CI at the same spectral efficiency.

Performance analysis of coordinate interleaved PLC system with Rayleigh channel gain under Nakagami‐ m additive noise

Power line communication (PLC) is an emerging field of communication that makes use of the existing power line infrastructure for the transmission of data and power. However, the presence of additive and multiplicative power line noises deteriorate the performance of a PLC system. Background and impulsive noises are the two main categories of additive noise, whereas channel gain accounts for the multiplicative noise. In this study, the authors propose coordinate interleaving (CI) technique and investigate its performance for a PLC system under the combined effect of Nakagami-m additive background noise and Rayleigh channel gain. They assume perfect channel state information at the transmitter and receiver of the PLC link. By interleaving the coordinates of the symbols sent over different channel realisations, CI results in significant improvement in the performance of a PLC system. Both the simulated and analytical results shown in this study reveal the effectiveness of the proposed technique in achieving better performance.

Performance of OFDM With Signal Space Diversity Using Subcarrier Coordinate Interleaving

Coordinate interleaving (CI) is applied to an orthogonal frequency division multiplexing system to exploit signal space diversity with binary phase-shift keying modulation. Two different CI strategies are introduced taking the correlation coefficients among the subcarrier channel gains into account. Accordingly, a number of different scenarios are investigated. Assuming Rayleigh fading, an exact closed-form expression on the bit error probability is derived. It is shown that the error performance of the system can be increased to a great extent with a feedback cost of a few bits and only a negligible increase in complexity. The proposed system is also shown to enhance the communication privacy under limited feedback.

OFDM With Index Modulation Using Coordinate Interleaving

Orthogonal frequency division multiplexing with index modulation (OFDM-IM), which uses the indices of the active subcarriers to transmit data, is a recently proposed multicarrier transmission technique. In this letter, we propose coordinate interleaved OFDM-IM (CI-OFDM-IM) by combining OFDM-IM and space-time block codes with coordinate interleaving. In this scheme, the real and imaginary parts of the data symbols are transmitted over different active subcarriers to achieve an additional diversity gain. The average bit error probability (ABEP) of the proposed scheme is derived and its superiority over the reference systems is shown via computer simulations.

Dynamic Subcarrier Coordinate Interleaving for Eavesdropping Prevention in OFDM Systems

In this letter, a novel anti-eavesdropping OFDM system through dynamic subcarrier coordinate interleaving is proposed by exploiting the reciprocal, location-dependent and time-varying nature of wireless channels. The transmitter performs coordinate interleaving at some of the OFDM subcarriers in an opportunistic manner, where the secret interleaving pattern is determined by the instantaneous channel state information (CSI) between the transmitter and intended receiver. More specifically, a subcarrier symbol associated with a channel phase larger than a predefined threshold is coordinate interleaved. Since wireless channels associated with each pair of users at separate locations exhibit independent multipath fading, the frequently updated coordinate interleaving pattern can only be shared between legitimate users based on channel reciprocity. Consequently, eavesdropping is prevented due to mismatched de-interleaving at the eavesdropper. Theoretical analysis and simulation results are provided to validate the proposed system.

Single-Symbol Maximum Likelihood Decodable STBCs with Fewer Zero-Entries

Two generalized constructions of single-symbol maximum likelihood (ML) decodable space-time block codes (SSDCs), the coordinate interleave orthogonal design (CIOD) and the generalized CIOD (GCIOD), have been proposed by Khan et al. Their main disadvantage is that there are too many zero entries in the codeword matrix. The transmission of these zero-valued symbols causes switching off some of the transmit antennas resulting in a high peak-to-average power ratio and also imposing a severe constraint on hardware implementation of the code. Based on the orthogonal construction of orthogonal space-time block codes and coordinate interleaving, a new generalized construction of SSDCs is proposed. Our proposed codes not only maintain the desirable properties of high rate, full transmit diversity and single-symbol ML decoding similar to CIODs and GCIODs, but also have fewer zero entries in its codeword matrix than CIODs and GCIODs.

A new layered MIMO-OFDM system with Signal Space Diversity

This paper aims to design a new transceiver with a signal space diversity (SSD) in layered multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. To this end, a enhanced coordinate interleaver (E-CI) that swaps a random pair of subcarriers is first proposed in order to realize readily the detection ordering required for a layered MIMO processing at the receiver. A enhanced maximum likelihood (E-ML) detection is also proposed in order to provide SSD gain after the MIMO detection processing. The performance of layered MIMO-OFDM system is evaluated and compared with that of MIMO-OFDM systems without the E-CI and E-ML detection over a time-varying Typical Urban (TU) channel.

An Efficient Differential MIMO-OFDM Scheme with Coordinate Interleaving

We propose a concatenated trellis code (TC) and coordinate interleaved differential space-time block code (STBC) for OFDM. The coordinate interleaver, provides signal space diversity and improves the codeword error rate (CER) performance of the system in wideband channels. Coordinate interleaved differential space-time block codes are proposed and used in the concatenated scheme, TC design criteria are derived, and the CER performances of the proposed system are compared with existing concatenated TC and differential STBC. The comparison showed that the proposed scheme has superior diversity gain and improved CER performance.

Power Allocation in MISO Channel With Co-Ordinate Interleaving Technique

This paper addresses the issue of peak-to-average power ratio (PAPR) reduction in multiple-input and single-output systems with a number of power allocation schemes. We propose a constellation-based power allocation scheme that is capable of achieving a lower PAPR when compared to the optimal power allocation scheme. Although this method of power allocation improves the PAPR performance, there is a slight degradation in bit error rate (BER) performance. However, the degradation in BER performance can be compensated through the use of co-ordinate interleaving technique. We also propose a constrained-optimal power allocation scheme with which it is possible to control the PAPR