Multiband Orthogonal Frequency Division Multiplexing Research Articles

UWB and MB-OFDM for Lunar Rover Navigation and Communication

This paper presents a comprehensive study of ultra-wideband (UWB) and multi-band orthogonal frequency-division multiplexing (MB-OFDM) technologies for lunar rover navigation and communication in challenging terrains. Lunar missions pose unique challenges, such as signal propagation in the lunar environment, terrain elevation, and rover movement constraints. To address these challenges, we propose a hybrid communication and navigation system that leverages UWB technology for high-precision positioning and MB-OFDM for robust and high-throughput communication. We develop a realistic simulation framework that incorporates terrain elevation, obstacles, and rover movement constraints, along with a simple fading model for communication. Simulation results demonstrate the effectiveness of the proposed system in navigating lunar rovers to their target locations while maintaining reliable communication links with a lunar lander. A novel approach based on game theory for rover navigation is also presented. The study provides valuable insights into the design and optimization of communication and navigation systems for future lunar missions, paving the way for seamless integration of advanced terrestrial technologies in extraterrestrial environments.

Low-Voltage Low Noise Figure Down-Conversion Mixer for Band #1 of MB-OFDM System in 180 nm Complementary Metal Oxide Semiconductor Technology

Low-voltage design is a challenge for Gilbert cell-based mixers due to stacking transconductance and switching stage. This work addresses this issue by proposing a design of a low-voltage down-conversion mixer for band #1 of multiband orthogonal frequency division multiplexing (MB-OFDM) system in 180 nm complementary metal oxide semiconductor (CMOS) technology. The mixer is tuned at band #1 at RF frequency of 3.432 GHz and IF frequency of 264 MHz. The proposed mixer uses folded cascode connection of LO and RF in order to increase headroom and to reduce the DC supply voltage for low-voltage operation. Common gate configuration is used at RF transconductance stage to enhance the input bandwidth of the mixer. RF and LO ports are matched to 50 Ω using differential T and LC matching, respectively. The resistive source denegation technique is used to linearize transconductance with respect to the bias point. The common source stage is used at the IF port as a buffer cum matching circuit it. The simulation results of the mixer show the maximum conversion gain of 9.76 dB, 1 dB compression point (P1dB) of -16.25 dBm, the third-order input intercept point (IIP3) of -4.70 dBm, an SSB noise figure of 9.036 dB, and S11of -19.490 dB at the supply voltage of 1.2 V. Excluding off chip components, proposed mixer records an active area of 926.35 μm2.

Analysis of Ultra Wide Band OFDM Communication System through IEEE802.15.4a in Wireless Communication

This paper uses simulation to evaluate the performance of a UWB communication system with an accurate channel model. A cost-effective prototype model of a real-time UWB communication system. This paper presents a UWB multiband OFDM system for various frequency ranges.Channel subgroups provide various models for the various frequency ranges of IEEE 802.15.4a. The UWB frame repeats from 2 to 10 GHz and provides 8-channel models for indoor and outdoor LOS (line-of-sight) and NLOS (no-line-of-sight) environmental conditions.The uniqueness of Task Group 4a channel models and UWB-enabled frameworks are reviewed and evaluated against a number of channel models.

Wideband ring mixer for band #1 of MB-OFDM systems in 180 nm CMOS technology

Abstract A wideband down conversion ring mixer is proposed for multi band orthogonal frequency division multiplexing (MB-OFDM) system in 180 nm CMOS technology. The mixer is essentially used in a heterodyne wireless receiver to enhance the selectivity of the system. Being a nonlinear system, the mixer dominates the overall performance of the system. The design of down conversion mixer is the most challenging part of a receive chain. Wideband impedance matching always remains a challenge in any radio frequency integrated circuit design. This paper presents the design of a ring mixer with high linearity, wideband impedance matching using differential resistive impedance matching and without using any DC bias. The proposed mixer is tuned for a frequency of 3.432 GHz of band 1 of the MB-OFDM system. Mixer core is based on the FET ring mixer topology. The mixer is implemented in 180 nm CMOS technology. The mixer achieves the minimum conversion loss of 10.49 dB, 1 dB compression point (P1) of 12.40 dBm, third order input intercept point (IIP3) of 12.01 dBm, a minimum SSB noise figure of 8.99 dB, and S 11 of less than -10 dB over the frequency range of 0 to 13.61 GHz . The layout of the mixer records an active area of 183.75 μm 2 .

Dimensioning an FPGA for Real-Time Implementation of State of the Art Neural Network-Based HPA Predistorter

Orthogonal Frequency Division Multiplexing (OFDM) is one of the key modulations for current and novel broadband communications standards. For example, Multi-band Orthogonal Frequency Division Multiplexing (MB-OFDM) is an excellent choice for the ECMA-368 Ultra Wideband (UWB) wireless communication standard. Nevertheless, the high Peak to Average Power Ratio (PAPR) of MB-OFDM UWB signals reduces the power efficiency of the key element in mobile devices, the High Power Amplifier (HPA), due to non-linear distortion, known as the non-linear saturation of the HPA. In order to deal with this limiting problem, a new and efficient pre-distorter scheme using a Neural Networks (NN) is proposed and also implemented on Field Programmable Gate Array (FPGA). This solution based on the pre-distortion concept of HPA non-linearities offers a good trade-off between complexity and performance. Some tests and validation have been conducted on the two types of HPA: Travelling Wave Tube Amplifiers (TWTA) and Solid State Power Amplifiers (SSPA). The results show that the proposed pre-distorter design presents low complexity and low error rate. Indeed, the implemented architecture uses 10% of DSP (Digital Signal Processing) blocks and 1% of LUTs (Look up Table) in case of SSPA, whereas it only uses 1% of LUTs in case of TWTA. In addition, it allows us to conclude that advanced machine learning techniques can be efficiently implemented in hardware with the adequate design.

A new insightful exploration into a low profile ultra-wide-band (UWB) microstrip antenna for DS-UWB applications

Designing a simple and planar antenna for high speed short distance ultra-wideband (UWB) communication has become a buzzword over the last few years. There are two very different categories of UWB technologies of vital relevance, i.e. (i) carrier-free direct sequence UWB (DS-UWB), and (ii) the Multi-Band orthogonal frequency division multiplexing UWB (OFDM UWB) technology. In, Multi-Band OFDM UWB technology, multi narrowband UWB antennas with frequency notches are required. However, in DS-UWB technology, the frequency spectrum of very short duration transmitted pulses occupies wide bandwidth, and hence to transmit it, the antenna should be fully matched over the entire bandwidth without the presence of any frequency notch. In this paper, a novel, small and completely planar air gap and defected ground slot integrated rectangular microstrip antenna with dual shorting posts have been thoroughly investigated to yield UWB, i.e. (109%) bandwidth without the presence of any frequency notch.

Proof-of-Concept of the Time and Spectral Optical Aggregation Network

In this article, we present the proof of concept (PoC) of the time and spectral optical aggregation (TISA) approach that allows a better filling of the time and spectral resources of an optical transport network. Some innovative solutions have been implemented, such as a new and fast tunable laser that permits to color the bursts sent in the TISA network, as well as their transmission with both DP-QPSK and DP-16QAM coherent multi-band (MB) OFDM formats. BER versus OSNR measurements have been achieved showing less than 1-dB penalty in back-to-back or after transmission. The tolerance of bursts against frequency mismatch occurring between the transceiver and the optical filter that extracts a sub-band inside the MB-OFDM signal has also been evaluated, and ∼1.5 GHz tolerance has been measured for bursts of ∼6.7 GHz bandwidth. Furthermore, in order to mitigate the transients in the coherent receiver that faces alternatively the presence or absence of signal, a novel channel estimator based on a sliding window has been introduced. Its efficiency and performance has been experimentally validated, and its ability to suppress the error threshold of the BER versus OSNR curves has been demonstrated. By the experimental proof of concept delivered here, the ability of the TISA network to perform with a good level of performance the transparent routing and sub-wavelength aggregation/disaggregation in the time and spectral domains simultaneously has been established. Beyond the important and crucial aspect of the optimal filling of the optical resources, our PoC demonstrate the ability of the TISA approach to push the flexibility of an optical transport network at its limit while allowing a cost and power consumption limitation obtained by the removal of costly and power-hungry optical-electrical-optical regenerators.

ICA based estimation and compensation of carrier frequency offset for MBOFDM based UWB systems

A carrier frequency offset (CFO) is addressed as a main type of wireless communication system imperfections in this paper. Carrier frequency offset (CFO) severely deteriorates the performance of OFDM receiver. Here an effective time domain CFO estimation and compensation method using symmetric subcarrier allocation (SCA) for multiband orthogonal frequency division multiplexing (MBOFDM) based ultra-wideband system is proposed. A data supported CFO estimation technique, which is robust to a larger offset, is presented as a novel method in compensation of CFO. An effective separation matrix scheme of OFDM signal with CFO is obtained. Subsequently, independent component analysis (ICA) based CFO estimation is stated. On fully exploiting the ECMA-368 preamble symbols, the proposed technique is capable for carrier frequency offset of 100 ppm, and the result is confirmed through simulations.

Mean Bit Error Rate Analysis of High Rate IEEE 802.15.3.a UWB Channels

In this work, the performance of ultra-wide band systems (UWB) in high-speed wireless networks is studied. At the physical layer of wireless personal area networks, dual carrier modulation driving multiband orthogonal frequency division multiplexing is implemented for 480 Mbps data rates over 4 classes of UWB scattering channels (CM1, CM2, CM3, CM4) bundeled as per the IEEE 802.15.3a UWB standard. Generalized wireless fading models are presented and canonical expressions for mean bit error rates (MBER) are derived for different modulation and receiver diversity combining schemes. A generating model in terms of the characteristic function of the signal-to-noise ratio is introduced for MBER under general statistical fading conditions, which further develops our previous work. The power density spectral characteristic of the multi-user noise is tuned to a novel generalized innovation-matched filter (GIMF) which is at the core of the UWB receiver. Because of its robustness at also capturing the fading characteristics of the UWB channels, the GIMF detector yields better performance than the classical matched filter and a 10-finger RAKE receiver. The relatively flat CM1 channel is proven to have the best performance, while the highly frequency selective CM4 suffers from the worst performance. CM3 channel slightly outperforms CM4 channel between 0 and 5 dB and exhibits significant improvement over CM4 above 5 dB SNR. CM3 and CM4 channels are proven to have nearly identical performance below 0 dB margins. A comparative analysis was also conducted for the MBER of our model and that of the CF-based model at a 10-finger RAKE receiver developed by Wang et al. It was found that our model outperforms that of the CF-model for CM1 and CM2 channels for a wide dynamic range of SNR values. For CM3 and CM4 channels, our model's performance was superior for SNR values below 8 dB.

RETRACTED ARTICLE: Enhancing the LTE-Based Intelligent Transportation System’s Performance

Intelligent transportation system is considered as one of the main features of the new generation of the wireless systems. Furthermore, both of high speed data transmission and processing play a crucial role for these generations. In this work, two main propositions have been detailed in order to attain an improvement in such intelligent systems performance and to enhance both of data transmission and processing speed. Thus, a proposed clustering algorithm will be presented for grouping mobile nodes based on their speeds besides the assignments of the head nodes that will not be updated every cycle, while the ordinary ones themselves will execute their attaching heads continuously. In order to enhance the speed of data transmission and processing, a parallel-processing technique is emphasized. This is based on a variety of wavelet baby functions to attain the target of increasing the speed with low complexity. In addition, the optimization of the transmitted power phenomenon, the Multiband orthogonal frequency division multiplexing is used to provide such privilege via the parallel processing criterion. There have been five main efficiency factors involved in this investigation; namely complementary cumulative distributions, bit rates, energy efficiency, the cluster head life time and the ordinary nodes reattaching-head average times.

Adaptive bandwidth control for multi-band OFDM transmission with spectrum sharing

Adaptive bandwidth control for multi-band OFDM transmission with spectrum sharing

Parameter estimation and channel reconstruction based on compressive sensing for ultra-wideband MB-OFDM systems

Multi-band orthogonal frequency-division multiplexing (MB-OFDM) is an important transmission technique for ultra-wideband (UWB) communication. One of the challenges for practical realization of these UWB MB-OFDM systems is the estimation of the channel. In UWB MB-OFDM, the channel can be modelled as sparse, and channel estimation (CE) based on compressed sensing (CS) can be used. However, the existing techniques all require prior knowledge of some channel parameters, which are not known in practice, e.g. the dictionary size, corresponding to the effective duration of the channel impulse response (CIR), and the sparsity of the CIR. Therefore, in this paper, we propose a CS-based channel parameter estimation method to estimate the dictionary size and the sparsity based on a pilot preamble of which the duration is shorter than the total duration of the CIR. Using the resulting parameter estimates, we reconstruct the CIR with the compressive sampling matching pursuit (CoSaMP) method. We show that the proposed algorithm is able to accurately estimate the sparsity and the dictionary size, and can effectively reconstruct the CIR for channels that are either based on a mathematical model or real, measured channels. Moreover, as the algorithm has acceptable complexity, the proposed method is suitable for practical use.

Closed-Form Analysis of Various Diversity Techniques for Multiband OFDM UWB System Over Log-Normal Fading Channels

In this paper, we investigate the effect of multipath fading on the combined signal-to-noise ratio (SNR) in conjunction with multiband orthogonal frequency division multiplexing ultra-wideband system with different diversity schemes such as maximal ratio combining, equal gain combining and selection combining. In particular, we derived the probability density function of the combiner output SNR followed by performance measures, average combined SNR, outage probability and average bit error rate, in the case of L-fold log-normal fading channels. The derived mathematical expressions are illustrated by applying the method to some selected numerical examples of interest showing the impact of fading variance as-well-as a number of diversity paths, which is combined, on the performance metrics of combiner output for above diversity techniques. The results show that the number of diversity paths significantly improve the effect of multipath fading on derived performance measures.

Analysis of UWB MB-OFDM Communication System through IEEE802.15.4a Channel Models using Matlab Simulink

This paper evaluates the performance of the UWB communication system with an accurate channel model using simulation. In real time a prototype model of UWB communication system is cost effective. This paper UWB Multiband-Orthogonal Frequency Division Multiplexing System is provided for various range of frequency. In various frequency range of IEEE 802.15.4a channel subgroup provides a several model. Ultra wideband frame work recurrence ranges from 2 to 10 GHz, and provides eight different models of channel for both Line-of-Sight (LOS) and No-line-of- Sight (NLOS) environment circumstances of both indoor as well as outdoor. The uniqueness of task group 4a Channel Models and UWB correspondence framework are confirmed and evaluated for numerous channel models.

Power reallocation and complexity enhancement for beyond 4G systems

Competitiveness in the modern wireless systems' provided services is a key factor in the development, in addition to the adaptation to/harmonization of user demand. Therefore, this paper discussed the quality of services from the point of view of the need for supporting the needed data rates. For this purpose, a benchmark based on Multi-Antenna Multiband Orthogonal Frequency Division Multiplexing has been proposed to compatible with Ultra-Wideband systems such as the fifth generation based technologies. In order to enhance the system quality of service, the structure of the ultra-wideband system's main stage; namely Orthogonal Frequency Division Multiplexing has been modified by imposing a low complexity designed Haar-wavelets stage instead of the fast Fourier transform stage. This is in addition to reallocate the transmitted power in order to reduce the effect of one of the main drawbacks that is found in the Orthogonal Frequency Division Multiplexing; namely the peak-to-average power ratio problem. A MATLAB simulation has been performed in order to validate the propositions that have been made based on six different performance factors. As a result, the new propositions were achieved our targets by reducing the system's complexity in terms of mathematical operations and by giving promising results in managing the transmitted powers. Furthermore, the effectiveness of such work has been verified and compared with four different work in the literature.

Spectral Efficiency Improving Technique in OCDMA-VLC system for IoT Application using Catenated-OFDM Modulation Scheme

Visible light communication (VLC) technology offers unregulated, unlicensed and huge bandwidth to meet the growing demand in future indoor communication system. One of the major challenge in VLC system is in improving transmission speed with optimize the bandwidth capacity. The method to improve spectral usage is using advanced modulation formats such as orthogonal frequency division multiplexing (OFDM). In this work, a new approach for modulation technique based on multiband OFDM has been developed which capable to improve the spectral efficiency and optimize the data rate. A proposed technique is then adapted in OCDMA-VLC environment to analyse the reliability of the proposed scheme in high capacity network. Different selection of parameter values such as bit rates, number of bands and effective received power will have different effect on the system performance. Numerical result shown that the catenated-OFDM outperforms conventional OFDM by five times spectral efficiency improvement and eight times spectral efficiency improvement at their five and eight number of bands respectively. It is also shown that the proposed catenated-OFDM design is working well even at very high bit rate of 15 Gbps. Moreover, there are enhancement in receiver sensitivity with 7.3 dB power penalty compared to previous work.

Linearization of multiband OFDM RoF system employing frequency-separated model based digital pre-distortion

To mitigate the nonlinear distortion of a multiband orthogonal frequency division multiplexing (OFDM) radio over fiber (RoF) system, a frequency-separated model-based digital pre-distortion (DPD) technique is proposed and experimentally demonstrated herein. Frequency-separated model DPD, when used as a pre-equalizer, mitigates nonlinearity in a transmitter. The nonlinear characteristic of an RoF system depends on the frequency band. Therefore, the proposed equalizer separates the input by frequency band and mitigates nonlinearities. A least mean square algorithm is used to estimate the variables of the proposed equalizer. Using the proposed DPD technique, performance enhancement was verified experimentally relative to the adjacent carrier leakage ratio (ACLR). The proposed technique obtained ACLR values of 27 to 30 dB. The results demonstrate that signal performance improved in terms of error vector magnitude from 6.3% to 3.5% at an optical modulation index value of 63%.

Channel‐based antenna synthesis for improved in‐vehicle UWB MB‐OFDM communications

Ultra-wide band (UWB) is an attractive technology for innovative in-vehicle wireless communications requiring high data rates and multiband orthogonal frequency division multiplexing (MB-OFDM) a suitable scheme for the accomplishment due to its high performance, low-power and low-cost characteristics. To contribute toward improved UWB MB-OFDM communications inside vehicles, a channel-based antenna synthesis technique to customise in-vehicle UWB antennas that reduce ‘blind spots’ in the communication channel is proposed and presented. For the realisation, a comprehensive analysis was utilised and comprised an in-car channel evaluation including bit-error-rate (BER) estimations and radiation pattern-and-source syntheses. The channel was measured using a standard antenna to set up the base of the experiments and the distribution of the impulse responses and signal-to-noise ratios in the vehicle's passenger plane shown. The currently available IEEE 802.15.3a channel models were perceived unrealistic for the in-vehicle application and the reason for measuring the channel practically. Using these specific channel measurements, the synthesised pattern is unveiled and consequently the channel-based antenna synthesis technique used to predict the antenna source. The antenna with optimised pattern-and-source showed an improved BER performance compared with the standard antenna in this application; that is, a figure of merit of 37.73% minimised ‘blind spots’.

Multiband Orthogonal Wavelet Division Multiplexing: Complexity and Power Peaks Enhancement

This article considers the existing wireless communications efficiency based on the multiband orthogonal frequency-division multiplexing (MBOFDM) benchmark. The power efficiency and frame error rates (FERs) have been investigated to find the peak-to-average-power ratio (PAPR) effect. Two impositions have been made to the benchmark: a new, lowcomplexity, Haar-based, discrete wavelet transform structure and a constant envelope transformation stage based on the pulsewidth modulation (PWM) technique.

Multi Band OFDM Alliance Power Line Communication System

This paper describes a new communication system that meets the quality of service requirements for home high speed communications. This system is based on Ultra-Wide Band (UWB) and Power Line Communication (PLC) technologies.The performances of our MBOA-PLC (Multi Band OFDM Alliance - Power Line Communication) system was evaluated by Matlab simulation to predict the efficiency of the UWB over PLC technology and their potential applications in the home network. The system compares the transmitted and received data to calculate the bit error rate (BER), based on the energy per bit to noise power spectral density ratio (Eb / N0). This is achieved by varying the number of information bits transmitted per OFDM symbol and the convolutional coding rate. The BER performance analysis presented in this study aims for a very high-speed transmission on indoor CPL channels, at more than 200 Mbps. The maximum data rate available on the market does not exceed 200 Mbps, despite the use of advanced coding and modulation systems, such as 1024 QAMs and the turbo-codes used for the Homeplug AV standard. The existing technology has little room to increase throughput because the available operational bandwidth limits the capacity of the channel.In the proposed PHY model for indoor PLC communications, QPSK mapping is used to provide good BER performance at high data rates that existing techniques have difficulty obtaining.