Efficient Estimation of CFO-Affected OFDM BER Floor in Small Cells with Resource-Limited IoT End-Points

Contemporary wireless networks dramatically enhance data rates and latency to become a key enabler of massive communication among various low-cost devices of limited computational power, standardized by the Long-Term Evolution (LTE) downscaled derivations LTE-M or narrowband Internet of Things (NB IoT), in particular. Specifically, assessment of the physical-layer transmission performance is important for higher-layer protocols determining the extent of the potential error recovery escalation upwards the protocol stack. Thereby, it is needed that the end-points of low processing capacity most efficiently estimate the residual bit error rate (BER) solely determined by the main orthogonal frequency-division multiplexing (OFDM) impairment–carrier frequency offset (CFO), specifically in small cells, where the signal-to-noise ratio is large enough, as well as the OFDM symbol cyclic prefix, preventing inter-symbol interference. However, in contrast to earlier analytical models with computationally demanding estimation of BER from the phase deviation caused by CFO, in this paper, after identifying the optimal sample instant in a power delay profile, we abstract the CFO by equivalent time dispersion (i.e., by additional spreading of the power delay profile that would produce the same BER degradation as the CFO). The proposed BER estimation is verified by means of the industry-standard LTE software simulator.

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Practical BER-Based Estimation of Residual OFDM CFO by Reducing Noise Margin

Wireless Communications and Mobile Computing ◽

10.1155/2020/8881436 ◽

2020 ◽

Vol 2020 ◽

pp. 1-5

Author(s):

Ante Mihaljević ◽

Adriana Lipovac ◽

Vlatko Lipovac ◽

Jasmin Musovic

Keyword(s):

Carrier Frequency Offset ◽

Signal To Noise Ratio ◽

Phase Error ◽

Average Power ◽

Small Time ◽

Small Cells ◽

Test Time ◽

High Power Amplifier ◽

Noise Margin ◽

Long Time

The main OFDM drawbacks are Carrier Frequency Offset (CFO) and large Peak-to-Average Power Ratio (PAPR), which both degrade the Bit Error Rate (BER). Specifically, we consider here clipping or any other PAPR reduction method sufficient to prevent the nonlinear high-power amplifier from generating errors. Moreover, in small cells, the signal-to-noise ratio is large, while the small time dispersion allows the OFDM symbol cyclic prefix to prevent intersymbol interference. This retains the CFO to solely determine the BER and vice versa, enabling indirect estimation of CFO-induced phase distortion by simple BER testing. However, a particular problem is measuring very low BER values (generated by alike residual CFO), which could last a long time in order to acquire statistically enough errors. The test time can be drastically reduced if the noise margin is reduced in a controllable way, by adding the interfering signal to each subcarrier at the receiver. This approach is shown to enable efficient and accurate short-term BER (and so CFO phase error) testing.

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INTER CARRIER INTERFERENCE AND SIGNAL TO INTERFERENCE RATIO OF VARIOUS PULSE SHAPING FUNCTIONS USED IN OFDM SYSTEM WITH CARRIER FREQUENCY OFFSET

International Journal of Electronics Signals and Systems ◽

10.47893/ijess.2012.1068 ◽

2012 ◽

pp. 68-71

Author(s):

SHANKAR AENAGANDULA ◽

ASHOK KUMAR ◽

SRINIVAS K ◽

MONIKA NANDA

Keyword(s):

Carrier Frequency ◽

Orthogonal Frequency Division Multiplexing ◽

Pulse Shaping ◽

Carrier Frequency Offset ◽

Signal To Noise Ratio ◽

Frequency Offset ◽

Performance Comparison ◽

Intercarrier Interference ◽

Ofdm Systems ◽

Ofdm System

Orthogonal Frequency Division Multiplexing (OFDM) is the important modulation of choice for fourthgeneration broadband multimedia wireless systems. This paper is focused on the problem of reducing the intercarrierinterference (ICI) and signal to noise ratio in the transmission over OFDM using various pulse shaping methods. Here we have performed a detailed performance comparison of various pulse shaping functions used in OFDM System with Carrier Frequency Offset. They appear to be suitable for transmission in OFDM systems with carrier frequency offset. The results obtained by analysis show that the performance improvement over conventional pulse shapes, are significant for reducing average intercarrier-interference (ICI) power and increased ratio of average signal power to average ICI power (SIR).

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Compressed Sensing Based Blind Carrier Frequency Offset Estimation for OFDM System

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.756-759.1894 ◽

2013 ◽

Vol 756-759 ◽

pp. 1894-1897 ◽

Cited By ~ 1

Author(s):

Gang Yang ◽

Hua Xin Yu ◽

Xiao Fei Zhang

Keyword(s):

Compressed Sensing ◽

Carrier Frequency ◽

Orthogonal Frequency Division Multiplexing ◽

Carrier Frequency Offset ◽

Signal To Noise Ratio ◽

Estimation Algorithm ◽

Frequency Offset ◽

Ofdm Systems ◽

Carrier Frequency Offset Estimation ◽

Sensing Model

In this paper, we address the problem of carrier frequency offset (CFO) estimation for Orthogonal Frequency Division Multiplexing (OFDM) systems. This paper links CFO estimation problem in OFDM systems to the compressed sensing model. Exploiting this link, it derives a compressed sensing-based CFO estimation algorithm. The proposed algorithm has better CFO estimation performance than ESPRIT method with lower signal-to-noise ratio (SNR). Simulation results illustrate performance of this algorithm.

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Model Kanal 5G dengan Pengaruh Kelembapan pada Frekuensi 3,3 GHz dan Bandwidth 99 MHz Berbasis Convolutional Codes

ELKOMIKA Jurnal Teknik Energi Elektrik Teknik Telekomunikasi & Teknik Elektronika ◽

10.26760/elkomika.v9i4.878 ◽

2021 ◽

Vol 9 (4) ◽

pp. 878

Author(s):

RENI DYAH WAHYUNINGRUM ◽

KHOIRUN NI’AMAH ◽

SOLICHAH LARASATI

Keyword(s):

Orthogonal Frequency Division Multiplexing ◽

Channel Model ◽

Signal To Noise Ratio ◽

Convolutional Codes ◽

Cyclic Prefix ◽

Frequency Division Multiplexing ◽

Frequency Division ◽

Signal To Noise ◽

Power Delay Profile ◽

Noise Ratio

ABSTRAKGenerasi telekomunikasi kelima (5G) diterapkan pada 2021 dengan frekuensi tinggi yang menyebabkan redaman yang besar dibandingkan pita sub-1 GHz. Penelitian ini mengkaji sistem 5G dengan frekuensi operasi 3,3 GHz dan bandwidth 99 MHz berdasarkan spesifikasi 5G dari Cyclic Prefix-Orthogonal Frequency Division Multiplexing (CP-OFDM) numerologi μ = 1 menggunakan parameter lingkungan yang diukur secara langsung di kota Bandung. Penelitian ini menemukan bahwa model kanal 5G dengan pengaruh kelembapan maksimum memiliki power delay profile (PDP) 9 path dengan nilai daya yang lebih kecil dan outage performances (𝑅>𝐶) yang lebih buruk dengan gap sebesar 0,3 dB dibandingkan dengan pengaruh kelembapan minimum. Hasil penelitian menunjukkan bahwa penggunaan convolutional codes dapat membantu menghemat Signal to Noise Ratio (SNR) dengan gap sebesar 3 dB. Hasil dari penelitian ini diharapkan dapat memberikan kontribusi bagi perkembangan komunikasi nirkabel 5G di Indonesia.Kata kunci: 5G, model kanal, convolutional codes, PDP, FER, BER. ABSTRACTThe fifth generation of telecommunications (5G) implemented in 2021, where high frequency which causes a large attenuation compared to the sub-1 GHz band. This research examines a 5G system with an operating frequency of 3.3 GHz and a bandwidth of 99 MHz based on the 5G specification of the Cyclic Prefix - Orthogonal Frequency Division Multiplexing (CP-OFDM) numerology μ = 1 using environmental parameters measured directly in Bandung, Indonesia. This research shows that the 5G channel model under maximum humidity has a 9 power delay profile (PDP) with a smaller power value and worse outage performances (𝑅>𝐶) with a gap of 0.3 dB compared to the effect of minimum humidity. The results showed that the use of convolutional codes can save the Signal to Noise Ratio (SNR) with gap of 3 dB. The results of this research are expected to contribute to the development of 5G wireless communications in Indonesia.Keywords: 5G, channel model, convolutional codes, PDP, FER, BER.

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All-Optical Non-Inverted Parity Generator and Checker Based on Semiconductor Optical Amplifiers

Applied Sciences ◽

10.3390/app11041499 ◽

2021 ◽

Vol 11 (4) ◽

pp. 1499

Author(s):

Bingchen Han ◽

Junyu Xu ◽

Pengfei Chen ◽

Rongrong Guo ◽

Yuanqi Gu ◽

...

Keyword(s):

Optical Amplifiers ◽

Signal To Noise Ratio ◽

Low Cost ◽

Extinction Ratio ◽

Semiconductor Optical Amplifiers ◽

Optical Signal ◽

Probe Light ◽

All Optical ◽

Negative Effect ◽

Parity Generator

An all-optical non-inverted parity generator and checker based on semiconductor optical amplifiers (SOAs) are proposed with four-wave mixing (FWM) and cross-gain modulation (XGM) non-linear effects. A 2-bit parity generator and checker using by exclusive NOR (XNOR) and exclusive OR (XOR) gates are implemented by first SOA and second SOA with 10 Gb/s return-to-zero (RZ) code, respectively. The parity and check bits are provided by adjusting the center wavelength of the tunable optical bandpass filter (TOBPF). A saturable absorber (SA) is used to reduce the negative effect of small signal clock (Clk) probe light to improve extinction ratio (ER) and optical signal-to-noise ratio (OSNR). For Pe and Ce (even parity bit and even check bit) without Clk probe light, ER and OSNR still maintain good performance because of the amplified effect of SOA. For Po (odd parity bit), ER and OSNR are improved to 1 dB difference for the original value. For Co (odd check bit), ER is deteriorated by 4 dB without SA, while OSNR is deteriorated by 12 dB. ER and OSNR are improved by about 2 dB for the original value with the SA. This design has the advantages of simple structure and great integration capability and low cost.

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PHY, MAC, and RLC Layer Based Estimation of Optimal Cyclic Prefix Length

Sensors ◽

10.3390/s21144796 ◽

2021 ◽

Vol 21 (14) ◽

pp. 4796

Author(s):

Adriana Lipovac ◽

Vlatko Lipovac ◽

Borivoj Modlic

Keyword(s):

Error Recovery ◽

Cyclic Prefix ◽

Closed Form Expression ◽

Delay Spread ◽

Radio Link ◽

Medium Access ◽

Power Delay Profile ◽

Rms Delay Spread ◽

Industry Standard ◽

New Radio

This work is motivated by growing evidence that the standard Cyclic Prefix (CP) length, adopted in the Long Term Evolution (LTE) physical layer (PHY) specifications, is oversized in propagation environments ranging from indoor to typical urban. Although this ostensibly seems to be addressed by 5G New Radio (NR) numerology, its scalable CP length reduction is proportionally tracked by the OFDM symbol length, which preserves the relative CP overhead of LTE. Furthermore, some simple means to optimize fixed or introduce adaptive CP length arose from either simulations or models taking into account only the bit-oriented PHY transmission performance. On the contrary, in the novel crosslayer analytical model proposed here, the closed-form expression for the optimal CP length is derived such as to minimize the effective average codeblock length, by also considering the error recovery retransmissions through the layers above PHY—the Medium Access Control (MAC) and the Radio Link Control (RLC), in particular. It turns out that, for given protective coding, the optimal CP length is determined by the appropriate rms delay spread of the channel power delay profile part remaining outside the CP span. The optimal CP length values are found to be significantly lower than the corresponding industry-standard ones, which unveils the potential for improving the net throughput.

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Event-Locked Time-Resolved Fourier Spectroscopy

Applied Spectroscopy ◽

10.1366/0003702971941917 ◽

1997 ◽

Vol 51 (8) ◽

pp. 1106-1112 ◽

Cited By ~ 20

Author(s):

H. Weidner ◽

R. E. Peale

Keyword(s):

Signal To Noise Ratio ◽

Low Cost ◽

Michelson Interferometer ◽

Far Infrared ◽

Time Base ◽

The Novel ◽

Time Resolved ◽

Mathematical Algorithm ◽

Scan Time ◽

Recorded Data

A low-cost method of adding time-resolving capability to commercial Fourier transform spectrometers with a continuously scanning Michelson interferometer has been developed. This method is specifically designed to eliminate noise and artifacts caused by mirror-speed variations in the interferometer. The method exists of two parts: (1) a novel timing scheme for synchronizing the transient events under study and the digitizing of the interferogram and (2) a mathematical algorithm for extracting the spectral information from the recorded data. The novel timing scheme is a modification of the well-known interleaved, or stroboscopic, method. It achieves the same timing accuracy, signal-to-noise ratio, and freedom from artifacts as step-scan time-resolving Fourier spectrometers by locking the sampling of the interferogram to a stable time base rather than to the occurrences of the HeNe fringes. The necessary pathlength-difference information at which samples are taken is obtained from a record of the mirror speed. The resulting interferograms with uneven pathlength-difference spacings are transformed into wavenumber space by least-squares fits of periodic functions. Spectra from the far-infrared to the upper visible at resolutions up to 0.2 cm−1 are used to demonstrate the utility of this method.

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Evaluation of PLC Channel Capacity and ABER Performances for OFDM-Based Two-Hop Relaying Transmission

Wireless Communications and Mobile Computing ◽

10.1155/2017/4827274 ◽

2017 ◽

Vol 2017 ◽

pp. 1-12 ◽

Cited By ~ 1

Author(s):

Sana Ezzine ◽

Fatma Abdelkefi ◽

Jean Pierre Cances ◽

Vahid Meghdadi ◽

Ammar Bouallégue

Keyword(s):

Channel Capacity ◽

Orthogonal Frequency Division Multiplexing ◽

Low Cost ◽

Relay Node ◽

Destination Node ◽

Direct Link ◽

Amplify And Forward ◽

Decode And Forward ◽

Maximum Ratio Combining ◽

The Impact

Powerline network is recognized as a favorable infrastructure for Smart Grid to transmit information in the network thanks to its broad coverage and low cost deployment. The existing works are trying to improve and adapt transmission techniques to reduce Powerline Communication (PLC) channel attenuation and exploit the limited bandwidth to support high data rate over long distances. Two-hop relaying BroadBand PLC (BB-PLC) system, in which Orthogonal Frequency Division Multiplexing (OFDM) is used, is considered in this paper. We derive and compare the PLC channel capacity and the end-to-end Average BER (ABER) for OFDM-based direct link (DL) BB-PLC system and for OFDM-based two-hop relaying BB-PLC system for Amplify and Forward (AF) and Decode and Forward (DF) protocols. We analyze the improvements when we consider the direct link in a cooperative communication when the relay node only transmits the correctly decoded signal. Maximum ratio combining is employed at the destination node to detect the transmitted signal. In addition, in this paper, we highlight the impact of the relay location on the channel capacity and ABER for AF and DF transmission protocols. Moreover, an efficient use of the direct link was also investigated in this paper.

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An EEG Experimental Study Evaluating the Performance of Texas Instruments ADS1299

Sensors ◽

10.3390/s18113721 ◽

2018 ◽

Vol 18 (11) ◽

pp. 3721 ◽

Cited By ~ 17

Author(s):

Usman Rashid ◽

Imran Niazi ◽

Nada Signal ◽

Denise Taylor

Keyword(s):

Experimental Study ◽

Mixed Models ◽

Signal To Noise Ratio ◽

Low Cost ◽

Low Frequency ◽

Low Power Consumption ◽

Motor Tasks ◽

Negative Peak ◽

Eeg Data ◽

Healthy Participants

Texas Instruments ADS1299 is an attractive choice for low cost electroencephalography (EEG) devices owing to its low power consumption and low input referred noise. To date, there have been no rigorous evaluations of its performance. In this EEG experimental study we evaluated the performance of the ADS1299 against a high quality laboratory-based system. Two self-paced lower limb motor tasks were performed by 22 healthy participants. Recorded power across delta, theta, alpha, and beta EEG bands, the power ratio across the motor tasks, pre-movement noise, and signal-to-noise ratio were obtained for evaluation. The amplitude and time of the negative peak in the movement-related cortical potentials (MRCPs) extracted from the EEG data were also obtained. Using linear mixed models, no statistically significant differences (p > 0.05) were found in any of these measures across the two systems. These findings were further supported by evaluation of cosine similarity, waveform differences, and topographic maps. There were statistically significant differences in MRCPs across the motor tasks in both systems. We conclude that the performance of the ADS1299 in combination with wet Ag/AgCl electrodes is analogous to that of a laboratory-based system in a low frequency (<40 Hz) EEG recording.

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An improved algorithm for polar cloud-base detection by ceilometer over the ice sheets

Atmospheric Measurement Techniques ◽

10.5194/amt-7-1153-2014 ◽

2014 ◽

Vol 7 (5) ◽

pp. 1153-1167 ◽

Cited By ~ 18

Author(s):

K. Van Tricht ◽

I. V. Gorodetskaya ◽

S. Lhermitte ◽

D. D. Turner ◽

J. H. Schween ◽

...

Keyword(s):

Seasonal Cycle ◽

Signal To Noise Ratio ◽

Low Cost ◽

Supercooled Liquid ◽

Cloud Base ◽

Polar Regions ◽

Detection Algorithms ◽

Humidity Measurements ◽

Using Data ◽

Mixed Phase Clouds

Abstract. Optically thin ice and mixed-phase clouds play an important role in polar regions due to their effect on cloud radiative impact and precipitation. Cloud-base heights can be detected by ceilometers, low-power backscatter lidars that run continuously and therefore have the potential to provide basic cloud statistics including cloud frequency, base height and vertical structure. The standard cloud-base detection algorithms of ceilometers are designed to detect optically thick liquid-containing clouds, while the detection of thin ice clouds requires an alternative approach. This paper presents the polar threshold (PT) algorithm that was developed to be sensitive to optically thin hydrometeor layers (minimum optical depth τ &geq; 0.01). The PT algorithm detects the first hydrometeor layer in a vertical attenuated backscatter profile exceeding a predefined threshold in combination with noise reduction and averaging procedures. The optimal backscatter threshold of 3 × 10−4 km−1 sr−1 for cloud-base detection near the surface was derived based on a sensitivity analysis using data from Princess Elisabeth, Antarctica and Summit, Greenland. At higher altitudes where the average noise level is higher than the backscatter threshold, the PT algorithm becomes signal-to-noise ratio driven. The algorithm defines cloudy conditions as any atmospheric profile containing a hydrometeor layer at least 90 m thick. A comparison with relative humidity measurements from radiosondes at Summit illustrates the algorithm's ability to significantly discriminate between clear-sky and cloudy conditions. Analysis of the cloud statistics derived from the PT algorithm indicates a year-round monthly mean cloud cover fraction of 72% (±10%) at Summit without a seasonal cycle. The occurrence of optically thick layers, indicating the presence of supercooled liquid water droplets, shows a seasonal cycle at Summit with a monthly mean summer peak of 40 % (±4%). The monthly mean cloud occurrence frequency in summer at Princess Elisabeth is 46% (±5%), which reduces to 12% (±2.5%) for supercooled liquid cloud layers. Our analyses furthermore illustrate the importance of optically thin hydrometeor layers located near the surface for both sites, with 87% of all detections below 500 m for Summit and 80% below 2 km for Princess Elisabeth. These results have implications for using satellite-based remotely sensed cloud observations, like CloudSat that may be insensitive for hydrometeors near the surface. The decrease of sensitivity with height, which is an inherent limitation of the ceilometer, does not have a significant impact on our results. This study highlights the potential of the PT algorithm to extract information in polar regions from various hydrometeor layers using measurements by the robust and relatively low-cost ceilometer instrument.

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