Channel Coding for Multi-Carrier Wireless Partial Duplex

In order to leverage the spectrum resources, several forms of wireless duplex have been introduced and investigated in recent years. In Partial Duplex (PD) schemes, part of the band is transmitted in Full-Duplex (FD) and the rest in Half-Duplex (HD); therefore, some transmitted symbols will be characterized, at the receiver, by high SNR (Signal-to-Noise Ratio) and others by low SNR because of the residual self-interference (SI) in the FD part. Combining properly the patterns of these high and low SNR symbols affects the performance of the encoding schemes used in the system; in order to overcome this issue, different encoding and allocation schemes can be adopted for achieving a satisfactory solution. This paper investigates the performance of Low-Density Parity-Check (LDPC), turbo, polar codes for wireless PD. Orthogonal Frequency Division Multiplexing (OFDM) is an efficient multicarrier modulation technique, used in 4G and in the upcoming 5G, and it can be exploited for realizing a proper symbol allocation according to the SNR on each subcarrier. In this context, performance of LDPC, polar, and turbo codes derived from existing specifications has been studied when the system faces a mixture of high and low SNRs on the bits and hence on the symbols coming from the same codeword and this unbalanced SNR distribution is known a-priori at the transmitter, a condition associated with a scheme in which part of the symbols is subject to FD interference.

Download Full-text

Automotive antenna diversity system for satellite radio with high phase accuracy in low SNR-scenarios

International Journal of Microwave and Wireless Technologies ◽

10.1017/s1759078718000296 ◽

2018 ◽

Vol 10 (5-6) ◽

pp. 578-586 ◽

Cited By ~ 4

Author(s):

Simon Senega ◽

Ali Nassar ◽

Stefan Lindenmeier

Keyword(s):

Signal To Noise Ratio ◽

A Priori ◽

Multipath Fading ◽

Correction Method ◽

Antenna System ◽

Antenna Diversity ◽

Phase Detection ◽

Low Snr ◽

Single Antenna ◽

Noise Correction

AbstractFor a fast scan-phase satellite radio antenna diversity system a noise correction method is presented for a significant improvement of audio availability at low signal-to-noise ratio (SNR) conditions. An error analysis of the level and phase detection within the diversity system in the presence of noise leads to a correction method based on a priori knowledge of the system's noise floor. This method is described and applied in a hardware example of a satellite digital audio radio services antenna diversity circuit for fast fading conditions. Test drives, which have been performed in real fading scenarios, are described and results are analyzed statistically. Simulations of the scan-phase antenna diversity system show higher signal amplitudes and availabilities. Measurement results of dislocated antennas as well as of a diversity antenna set on a single mounting position are presented. A comparison of a diversity system with noise correction, the same system without noise correction, and a single antenna system with each other is performed. Using this new method in fast multipath fading driving scenarios underneath dense foliage with a low SNR of the antenna signals, a reduction in audio mute time by one order of magnitude compared with single antenna systems is achieved with the diversity system.

Download Full-text

A Full-Duplex LED-to-LED Visible Light Communication System

Electronics ◽

10.3390/electronics9101713 ◽

2020 ◽

Vol 9 (10) ◽

pp. 1713

Author(s):

Hyunwoo Jung ◽

Sung-Man Kim

Keyword(s):

Visible Light ◽

Bit Error Rate ◽

Error Rate ◽

Signal To Noise Ratio ◽

Light Emitting Diode ◽

Visible Light Communication ◽

Full Duplex ◽

Signal To Noise ◽

Light Emitting ◽

Half Duplex

We experimentally demonstrated full-duplex light-emitting diode (LED)-to-LED visible light communication (VLC) using LEDs as the transmitter and receiver. Firstly, we investigated the performance dependency on the wavelengths of the LED transmitter and receiver by measuring the rise time and signal-to-noise ratio (SNR). Through the investigation, we were able to choose the optimal LED color set for LED-to-LED VLC using Shannon’s channel capacity law. The bit error rate (BER) results of full-duplex and half-duplex LED-to-LED VLC systems with the optimal LED sets are shown to compare the performance. Furthermore, we discuss major distortions and signal losses in the full-duplex LED-to-LED VLC system.

Download Full-text

A Low-Complexity Ordered Statistics Decoding Algorithm for Short Polar Codes

Applied Sciences ◽

10.3390/app9050831 ◽

2019 ◽

Vol 9 (5) ◽

pp. 831

Author(s):

Yusheng Xing ◽

Guofang Tu

Keyword(s):

Error Correction ◽

Error Rate ◽

Complexity Analysis ◽

Signal To Noise Ratio ◽

Low Complexity ◽

High Signal ◽

Polar Codes ◽

Decoding Algorithm ◽

Low Snr ◽

Ordered Statistics

In this paper, we propose a low-complexity ordered statistics decoding (OSD) algorithm called threshold-based OSD (TH-OSD) that uses a threshold on the discrepancy of the candidate codewords to speed up the decoding of short polar codes. To determine the threshold, we use the probability distribution of the discrepancy value of the maximal likelihood codeword with a predefined parameter controlling the trade-off between the error correction performance and the decoding complexity. We also derive an upper-bound of the word error rate (WER) for the proposed algorithm. The complexity analysis shows that our algorithm is faster than the conventional successive cancellation (SC) decoding algorithm in mid-to-high signal-to-noise ratio (SNR) situations and much faster than the SC list (SCL) decoding algorithm. Our addition of a list approach to our proposed algorithm further narrows the error correction performance gap between our TH-OSD and OSD. Our simulation results show that, with appropriate thresholds, our proposed algorithm achieves performance close to OSD’s while testing significantly fewer codewords than OSD, especially with low SNR values. Even a small list is sufficient for TH-OSD to match OSD’s error rate in short-code scenarios. The algorithm can be easily extended to longer code lengths.

Download Full-text

Pilot-Based Time Domain SNR Estimation for Broadcasting OFDM Systems

Journal of Computer Networks and Communications ◽

10.1155/2018/9319204 ◽

2018 ◽

Vol 2018 ◽

pp. 1-8

Author(s):

Abid Muhammad Khan ◽

Varun Jeoti ◽

Muhammad Zaka Ur Rehman ◽

Muhammad Taha Jilani ◽

Omer Chugtai ◽

...

Keyword(s):

Time Domain ◽

Orthogonal Frequency Division Multiplexing ◽

Signal To Noise Ratio ◽

Ofdm Systems ◽

Ofdm System ◽

Significant Saving ◽

Snr Estimation ◽

Channel Changes ◽

Low Snr ◽

Estimation Scheme

The estimation of signal-to-noise ratio (SNR) is a major issue in wireless orthogonal frequency-division multiplexing (OFDM) system. In OFDM system, each frame starts with a preamble symbol that facilitates the SNR estimation. However, the performance of preamble-based SNR estimation schemes worsens in the fast-changing environment where channel changes symbol to symbol. Accordingly, in this paper, we propose a novel pilot-based SNR estimation scheme that optimally exploits the pilot subcarriers that are inserted in each data symbol of the OFDM frame. The proposed scheme computes the circular correlation between the received signal and the comb-type pilot sequence to obtain the SNR. The simulation results are compared with the conventional preamble-based Zadoff-Chu sequence SNR estimator. The results indicate that the proposed scheme generates near-ideal accuracy; especially in low SNR regimes, in terms of the normalized mean square error (NMSE). Moreover, this scheme offers a significant saving of computation over a conventional time domain SNR estimator.

Download Full-text

An Improved Channel Estimation Algorithm Based on WD-DDA in OFDM System

Mobile Information Systems ◽

10.1155/2021/6540923 ◽

2021 ◽

Vol 2021 ◽

pp. 1-9

Author(s):

Dan Wang ◽

Zhiqiang Mei ◽

Jiamin Liang ◽

Jinzhi Liu

Keyword(s):

Channel Estimation ◽

Orthogonal Frequency Division Multiplexing ◽

Signal To Noise Ratio ◽

Estimation Algorithm ◽

Transform Domain ◽

Ofdm System ◽

Low Snr ◽

Estimation Algorithms ◽

Residual Noise ◽

First Time

Channel estimation is the key technology to ensure reliable transmission in orthogonal frequency division multiplexing (OFDM) system. In order to improve the accuracy of the channel estimation algorithm in a low signal-to-noise ratio (SNR) channel environment, in this paper, we proposed an improved channel estimation algorithm based on the transform domain. The improved algorithm with wavelet denoising (WD) and distance decision analysis (DDA) to perform secondary denoising on the channel estimation algorithm based on the transform domain is proposed. First, after the least-squares (LS) algorithm, WD is used to denoise for the first time, then the DDA is used to further suppress the residual noise in the transform domain, and the important channel taps are screened out. Simulation results show that the proposed algorithm can improve the detection performance of existing channel estimation algorithms based on transform domain in low SNR.

Download Full-text

Performance analysis of NR Polar Codes at short information blocks for control channels

10.21203/rs.3.rs-203428/v1 ◽

2021 ◽

Author(s):

Tirthadip Sinha ◽

Jaydeb Bhaumik

Keyword(s):

Performance Analysis ◽

Error Correction ◽

Channel Coding ◽

Signal To Noise Ratio ◽

Additive White Gaussian Noise ◽

Early Termination ◽

Polar Codes ◽

Cyclic Redundancy Check ◽

Polar Code ◽

Trade Offs

Abstract One important innovation in information and coding theory is polar code, which delivers capacity attaining error correction performance varying code rates and block lengths. In recent times, polar codes are preferred to offer channel coding in the physical control channels of the 5G (5 th Generation) wireless standard by 3GPP (Third Generation Partnership Project) New Radio (NR) group. Being a part of the physical layer, Channel coding plays key role in deciding latency and reliability of a communication system. However, the error correction performance degrades with decreased message lengths. 5G NR requires channel codes with low rates, very low error floors with short message lengths and low latency in coding process. In this work, Distributed Cyclic Redundancy Check Aided polar (DCA-polar) code along with Cyclic Redundancy Check Aided polar (CA-polar) code, the two variant of polar codes have been proposed which provide significant error-correction performance in the regime of short block lengths and enable early termination of decoding processes. While CRC bits improve the performance of SCL (successive cancellation list) decoding by increasing distance properties, distributed CRC bits permit path trimming and early-termination of the decoding process. The design can reduce the decoding latency and energy consumption of hardware, which is crucial for mobile applications like 5G. The work also considers the performance analysis of NR polar codes over AWGN (Additive White Gaussian Noise) for short information block lengths at low code rates in the uplink and downlink control channels using SNR (Signal to Noise Ratio) and FAR (False Alarm Rate) as the performance measures. Simulation results illustrate different trade-offs between error-correction and detection performances comparing proposed NR polar coding schemes.

Download Full-text

MIMO-OFDM equaliser for spatial multiplexing transmission modes

Advances in Radio Science ◽

10.5194/ars-8-81-2010 ◽

2010 ◽

Vol 8 ◽

pp. 81-85 ◽

Cited By ~ 1

Author(s):

P. Beinschob ◽

U. Zölzer

Keyword(s):

Channel Coding ◽

Orthogonal Frequency Division Multiplexing ◽

Multiple Input Multiple Output ◽

Spatial Multiplexing ◽

Performance Loss ◽

Low Snr ◽

Input Multiple Output ◽

Spatial Interference ◽

The Impact ◽

Ber Performance

Abstract. In search for faster and more reliable communication, multiple-input multiple-output (MIMO) in conjuction with Orthogonal Frequency Division Multiplexing (OFDM) are subject of extensive research. In spatial multiplexing transmission an instantaneous rise of data rates governed by the number of transmit antennas can be realised. The system performance depends highly on signal-to-interference-plus-noise ratios (SINR) at the receiver. The receiver's equaliser is supposed to maximize the SINR by mitigating the spatial interference and thus separating the transmitted signals. For this problem several solutions exist such as linear and nonlinear, per subcarrier or OFDM symbol-based. An overview of common algorithms is given and complexity is discussed. Bit error rate (BER) performance evaluations are presented. Another aspect is the impact of the equalisation strategy on the performance of bit-interleaved soft information-based channel coding schemes. As a representative, LDPC codes are chosen. Simulation results show a significant BER performance loss for symbol decision-based equalisers compared to the uncoded performance. To overcome this problem a modification of the Maximum Likelihood algorithm is proposed which yields good performance for low SNR applications.

Download Full-text

Improvement of Fast Simplified Successive-Cancellation Decoder for Polar Codes

Information ◽

10.3390/info9100254 ◽

2018 ◽

Vol 9 (10) ◽

pp. 254

Author(s):

Chao Xing ◽

Zhiliang Huang ◽

Shengmei Zhao

Keyword(s):

Reduction Method ◽

Signal To Noise Ratio ◽

Code Rate ◽

Polar Codes ◽

Latency Reduction ◽

Low Snr ◽

Successive Cancellation ◽

Current Node ◽

Reduction Methods ◽

Check Condition

This paper presents a new latency reduction method for successive-cancellation (SC) decoding of polar codes that performs a frozen-bit checking on the rate-other (R-other) nodes of the Fast Simplified SC (Fast-SSC) pruning tree. The proposed method integrates the Fast-SSC algorithm and the Improved SSC method (frozen-bit checking of the R-other nodes). We apply a recognition-based method to search for as many constituent codes as possible in the decoding tree offline. During decoding, the current node can be decoded directly, if it is a special constituent code; otherwise, the frozen-bit check is executed. If the frozen-bit check condition is satisfied, the operation of the R-other node is the same as that of the rate-one node. In this paper, we prove that the frame error rate (FER) performance of the proposed algorithm is consistent with that of the original SC algorithm. Simulation results show that the proportion of R-other nodes that satisfy the frozen-bit check condition increases with the signal-to-noise-ratio (SNR). Importantly, our proposed method yields a significant reduction in latency compared to those given by existing latency reduction methods. The proposed method solves the problem of high latency for the Improved-SSC method at a high code rate and low SNR, simultaneously.

Download Full-text

Orthogonal frequency division multiplexing with amplitude shift keying subcarrier modulation as a reliable and efficient transmission scheme for self-mixing receivers

Advances in Radio Science ◽

10.5194/ars-15-99-2017 ◽

2017 ◽

Vol 15 ◽

pp. 99-106 ◽

Cited By ~ 2

Author(s):

Jonas Kornprobst ◽

Thomas J. Mittermaier ◽

Thomas F. Eibert

Keyword(s):

Power Efficiency ◽

Orthogonal Frequency Division Multiplexing ◽

Phase Retrieval ◽

Signal To Noise Ratio ◽

A Priori ◽

Strong Dependence ◽

Equation System ◽

The Self ◽

Transmission Scheme ◽

Available Bandwidth

Abstract. A new receiving scheme for self-mixing receivers is presented that overcomes the disadvantages of the self-heterodyne concept. Generally speaking, the self-mixing receiver offers immunity to phase noise and frequency offsets, especially at very high frequencies, since it does not require radio frequency local oscillators. Our proposed technique eliminates the drawbacks of the self-heterodyne transmission scheme, which are the poor power efficiency and the strong dependence on the continously transmitted carrier. A nonlinear system of equations is constructed that describes a phase retrieval problem for the reconstruction of the original transmit signal before self-mixing. Two different solution strategies, with restrictions in time and frequency domain, are presented. As a consequence, the self-mixing equation system is shown to be solvable with some a-priori information about the transmit signal. With this novel approach, the transmitted information is distributed over the full available bandwidth, and there is no special dependence on a certain subcarrier for the down-conversion. The general performance, regarding bit error ratio over signal to noise ratio, is improved by at least 2 dB as compared to the self-heterodyne transmission scheme. In the case of frequency selective channels, e.g. multi-path propagation, this improvement is shown to be much larger, because the presented approach is able to reconstruct the received subcarriers without the necessity of receiving all subcarriers.

Download Full-text

Comparison between Different Channel Coding Techniques for IEEE 802.11be within Factory Automation Scenarios

Sensors ◽

10.3390/s21217209 ◽

2021 ◽

Vol 21 (21) ◽

pp. 7209

Author(s):

Lorenzo Fanari ◽

Eneko Iradier ◽

Iñigo Bilbao ◽

Rufino Cabrera ◽

Jon Montalban ◽

...

Keyword(s):

Turbo Codes ◽

Channel Coding ◽

Additive White Gaussian Noise ◽

Convolutional Codes ◽

Polar Codes ◽

Wireless System ◽

Factory Automation ◽

Require Time ◽

New Radio

This paper presents improvements in the physical layer reliability of the IEEE 802.11be standard. Most wireless system proposals do not fulfill the stringent requirements of Factory Automation use cases. The harsh propagation features of industrial environments usually require time retransmission techniques to guarantee link reliability. At the same time, retransmissions compromise latency. IEEE 802.11be, the upcoming WLAN standard, is being considered for Factory Automation (FA) communications. 802.11be addresses specifically latency and reliability difficulties, typical in the previous 802.11 standards. This paper evaluates different channel coding techniques potentially applicable in IEEE 802.11be. The methods suggested here are the following: WLAN LDPC, WLAN Convolutional Codes (CC), New Radio (NR) Polar, and Long Term Evolution (LTE)-based Turbo Codes. The tests consider an IEEE 802.11be prototype under the Additive White Gaussian Noise (AWGN) channel and industrial channel models. The results suggest that the best performing codes in factory automation cases are the WLAN LDPCs and New Radio Polar Codes.

Download Full-text