Wavelet OFDM Research Articles

Wavelet OFDM Wireless Communication System for Autonomous Underwater Vehicles Using Loop-Shaped Antennas in Underwater Environments

Wavelet OFDM Wireless Communication System for Autonomous Underwater Vehicles Using Loop-Shaped Antennas in Underwater Environments

Massive MIMO NOMA with wavelet pulse shaping to minimize undesired channel interference

In this article, wavelet OFDM based non-orthogonal-multiple-access (NOMA) combined with massive MIMO system for 6G networks is proposed. For mMIMO transmissions, the proposed system could enhance the performance by utilizing wavelets to compensate for channel impairments on the transmitted signal. Performance measures include spectral efficiency, symbol error rate (SER), and peak to average ratio (PAPR). Simulation results prove that the proposed system outperforms the conventional OFDM based NOMA systems.

Analysis performance of wavelet OFDM in mobility platforms

Wavelet orthogonal frequency division multiplexing (OFDM) is one of the medium access techniques recommended by the IEEE 1901 working group for broadband communications over electrical networks, and is under consideration for IoT applications. This standard provides a flexible architecture supporting integrated access, smart grid, building, in-home, and mobility platform (vehicle) applications. Wavelet OFDM is a filter bank multicarrier system based on the extended lapped transform, in which the transmitting and receiving filters are obtained from a waveform provided by the standard. In this paper, we explore system performance when other waveforms are employed, studying the trade-off between stopband attenuation and transition band width. Furthermore, an alternative and more efficient way of obtaining the theoretical expressions of the achievable data rate is shown, assuming realistic power line communication noise other than additive white Gaussian noise. To demonstrate the capabilities of wavelet OFDM, the results of simulation of the symbol error rate and the data rate in several systems in platform scenarios (in-vehicle and in-aircraft) are shown.

Performance analysis of discrete wavelet transform for downlink non‐orthogonal multiple access in 5G networks

Non-orthogonal multiple access (NOMA) has been considered a key technology to address the increasing traffic demands for fifth-generation (5G) cellular wireless communication networks and internet of things. The NOMA technique offers efficient bandwidth utilisation, low latency, and support for the massive connectivity of devices in 5G networks. In the conventional NOMA system, orthogonal frequency division multiplexing (OFDM) is used as a pulse-shaping technique that causes high peak to average power ratio (PAPR) due to the superposition of signals of multiple users after passing through inverse fast Fourier transform and spectral inefficiency due to the cyclic prefix insertion. Therefore, an alternate methodology using wavelet OFDM is proposed in this research work, as a pulse-shaping technique for NOMA-based communication systems to improve spectral efficiency and system capacity The main contribution of this study is the analysis of the bit error rate (BER) performance and the effect of carrier frequency offset on system performance of wavelet NOMA (W-NOMA) technique in 5G networks. The simulation results demonstrate that W-NOMA outperforms the conventional NOMA with reference to PAPR and BER.

A bandpass wavelet OFDM system for power line communications

A bandpass wavelet OFDM system, based on the time-domain waveform signals described in the standard IEEE Std. 1901-2010 for broadband power line communications, is presented. Several important aspects of the bandpass physical layer are reviewed, focusing on the scheme of modulation. Furthermore, a viable receiver system that is compatible with the transmitter and that also includes an equalizer system, is proposed. This paper also derives theoretical expressions for different powers at the receiver side, corresponding to the desired signal, as well as to the intersymbol and the intercarrier interference, and the noise. With these expressions, the signal-to-interference plus noise ratio and the achievable data rate of wavelet OFDM for bandpass communications are calculated. Finally, several computer simulations complete this work, assuming different PLC scenarios.

Adaptive $2\times2$ MIMO Employed Wavelet-OFDM-Radio Over Fibre Transmission

Due to high peak-to-average-power ratio (PAPR) and low spectral-efficiency, the conventional Fast Fourier Transform based orthogonal frequency division multiplexing (OFDM) is losing its place to the other multicarrier modulation schemes. Alternatively, the wavelet treated multiple-input multiple-output (MIMO)-OFDM is gaining its popularity in realization of futuristic 5G networks due to proffering high spectral-efficiency, low-cost and low phase-noise. Subsequently, this work demonstrates a RF transmission system in S-band employing $2 \times 2$ MIMO-OFDM using orthogonal- and biorthogonal-wavelets with diverse phase shift keying modulation (PSK) schemes. Among the available MIMO configurations, the authors implement spatial diversity as it promises good reliability in noisy links [11] . However, the distribution of Wavelet-OFDM (W-OFDM) signals over a radio over fibre (RoF) link is critically affected by the optical sub-system non-linearity. So, the simplest $2 \times 2$ Alamouti’s space-time block code (STBC) is implemented in this work to overcome this non-linearity and to realize a less-complex detection. The work is further extended to realize an adaptive MIMO-RoF system employing W-OFDM scheme to adjust itself to a suitable available phase shift keying strategy as per the link-situation to retain an optimal balance of link-quality and spectral-efficiency.

Performance investigation of WOFDM for 5G wireless networks

<p>Nowadays, emerging wireless networks scenarios such as the proposed systems for 5G is discussed widely with diverse requirements. Orthogonal Frequency Division Multiplexing (OFDM) is a conservative proposal which is used to build 5G WOFDM system (Wavelet OFDM system). The simulation of the system is initialized with BPSK then with QAM and 64-QAM the system is improved by increasing the number of levels of Discrete Wavelet Transform to five levels and finally compared with original system to prove that the it is convenient for 5G Wireless networks.</p>

A-STBC incorporated power-efficient Radio over Fibre system

MIMO–OFDM based Radio over Fibre (RoF) system has emerged as a potential candidate to realize highly-reliable, power- and spectral-efficient wireless systems. However, low spectral-efficiency in conjunction with high peak-to-average power ratio (PAPR) of the FFT based conventional OFDM degrades the system performance and demands high power to attain the required BER. To reduce this high power requirement to attain the threshold BER (10−3), a discrete wavelet transform (DWT) approach is incorporated with conventional MIMO–OFDM-RoF system in this work. The proposed Wavelet-OFDM (W-OFDM) system is integrated with Alamouti-Space–time Block Codes (A-STBC) and the resulting MIMO–OFDM signal is transported over a RoF link of 10 Km in the presence of non-linearity. Moreover, at radio access point (RAP), the received RF signals are transmitted over Rayleigh faded wireless-channel in the presence of additive white Gaussian noise (AWGN) and phase-offset arising due to imperfect carrier phase-estimation. The proposed system equipped with 16-PSK and 64-PSK modulation schemes claims power efficacy of 68% and 40% respectively in achieving the threshold BER in contrast to the conventional system under low non-linearity scenario.

Wavelet OFDM with Overlap FDE for non-Gaussian channels in precoded NOMA based systems

Non-orthogonal multiple access (NOMA) is considered as a prominent multiple access technique for fifth generation (5G) systems mainly because of its high spectral efficiency (SE). NOMA based system employs superposition coding (SC) and successive interference cancellation (SIC) at the transmitter and receiver side respectively. Classical multi-carrier NOMA adopts orthogonal frequency division multiplexing (OFDM) as a multi-carrier modulation (MCM) technique; however, high peak to average power ratio (PAPR) and cyclic prefix (CP) inclusion makes OFDM an inadequate choice for NOMA. To improve SE of the OFDM-NOMA, wavelet transform (WT) has been proposed for NOMA. This article proposes new physical layer techniques based on OFDM-NOMA and Wavelet OFDM (WOFDM) -NOMA for tactile internet and investigates their performance in the presence of Gaussian and non-Gaussian channels. Overlap frequency domain equalization (OFDE) is proposed as a robust equalization technique to improve the performance of SIC in the presence of Gaussian and non-Gaussian channels for OFDM-NOMA and WOFDM-NOMA. Moreover, to enhance the equalization efficiency of the OFDE, linear precoding (LP) in the form of Walsh Hadamard transform (WHT) is also recommended for OFDM and WOFDM based NOMA transceivers which improves the reliability of the network. Performance of the proposed precoded OFDM-NOMA and precoded WOFDM-NOMA with OFDE is analyzed in the presence of additive white Gaussian noise (AWGN) and impulse noise for Rayleigh fading channel. Link level performance of the presented structures for downlink NOMA is evaluated in terms of bit error rate (BER), PAPR, SE and computational complexity (CC). Furthermore, performance of the proposed architectures is also compared in the presence of impulse noise having different intensities. Simulation results via computer show that the proposed precoded WOFDM-NOMA with OFDE transceiver incorporates low latency through waveform shaping and enhanced reliability through precoding and efficient equalization. Thus, proposed advanced physical layer not only performs better than its counterparts but presence of OFDE enhances SIC performance even in the presence of impulse noise at the expense of slight elevation in CC.

Comparative Analysis of ICI Self Cancellation Techniques for Wavelet OFDM Under Different Channels in Simulink

Orthogonal frequency division multiplexing (OFDM) has found its place in many applications due to its advantages like robustness to channel fading,spectral efficiency and high data rate. Long Term Evolution and Wi-Fi utilises OFDM. Some practical limitations faced by OFDM are Inter carrier Interference(ICI) and Peak to Average Power Ratio(PAPR). Many schemes to combat the ICI and PAPR are available. In this paper, we analyze the different ICI self cancellation techniques proposed in literature. Further, these techniques are integrated with wavelet based OFDM. ICI Self Cancellation techniques for wavelet OFDM are compared under different channels using Simulink.

Dual PHY Layer for Non-Orthogonal Multiple Access Transceiver in 5G Networks

Non-orthogonal multiple access (NOMA) is a promising multiple access technique, proposed in literature for the fifth generation (5G) mobile networks. The NOMA system model consists of the conventional orthogonal frequency division multiplexing (OFDM), as a pulse shaping technique in conjunction with a variable power domain for various users, allocated in proportion to each user’s channel gain. OFDM technique based on wavelet filter banks, namely wavelet OFDM (WOFDM) has been utilized in digital communication to improve the system robustness to noise and adjacent channel interference, and is therefore anticipated to be adopted for the NOMA technique. WOFDM in NOMA (WNOMA) outperforms OFDM-based conventional NOMA (CNOMA) with reference to interference mitigation, bandwidth efficiency, spectral confinement, and multi-user capacity. Most of the fourth generation (4G) networks are based on OFDM and its variants. Therefore, in this paper, keeping in view the interoperability with the 4G networks and the latency requirements in 5G, a dual physical layer based on conventional OFDM and WOFDM as pulse shaping methods, is proposed for the NOMA transceiver. Performance of WNOMA and CNOMA is analyzed for bit error rate in the presence of channel impairments including additive noise and IQ imbalance and multiuser capacity is also computed. Comparison of various parameters indicates the advantage of adopting WNOMA over its conventional counterpart for relatively poor channel conditions.

Throughput Analysis of Wavelet OFDM in Broadband Power Line Communications

Windowed orthogonal frequency-division multiplexing (OFDM) and wavelet OFDM have been proposed as multicarrier techniques for broadband communications over the power line network by the standard IEEE 1901. The windowed OFDM has been extensively researched and employed in different fields of communication, while the wavelet OFDM has been recently recommended for the first time in a standard. This paper is aimed to show that the wavelet OFDM, which basically is an extended lapped transform-based multicarrier modulation (ELT-MCM), is a viable and attractive alternative for data transmission in hostile scenarios, such as in-home power line communications (PLC). To this end, we obtain theoretical expressions for ELT-MCM of: 1) the desired signal power; 2) the inter-symbol interference power; 3) the inter-carrier interference power; and 4) the noise power at the receiver side. These expressions are used to derive the throughput. This paper includes several computer simulations that show that ELT-MCM is an efficient alternative to improve data rates in the PLC systems.

Linear precoded wavelet OFDM‐based PLC system with overlap FDE for impulse noise mitigation

SummaryIn recent years, power lines have gained significant interest for their use in high‐speed communications because of the already deployed power distribution infrastructure. However, to achieve high data rates with reliability in power line communication (PLC), robust signal processing techniques are required to mitigate channel distortion and noise. Orthogonal frequency division multiplexing (OFDM) as a multicarrier modulation technique has been standardized for PLC; however, to further enhance the quality of communication, wavelet OFDM (WOFDM) has been proposed as a suitable choice. In this article, OFDM‐based and WOFDM‐based PLC systems are studied, and overlap frequency domain equalization (OFDE) as a robust and efficient equalization technique is presented. Moreover, to enhance the efficiency of the OFDE, linear precoding (LP) is also suggested for fast Fourier transform and wavelet transform–based filter bank transceivers over the PLC channel. Performance of the proposed LP‐based OFDM‐OFDE and LP‐based WOFDM‐OFDE systems is compared with previously proposed equalization structures in terms of bit error rate, peak‐to‐average power ratio, and computational complexity via computer simulations. Furthermore, the performance of proposed architectures is also compared with classical equalization techniques under impulse noise with different intensities. Results show that not only the proposed LP‐based WOFDM‐OFDE transceiver performs better than the previous equalization models but also the LP‐based OFDM‐OFDE at the expense of slight increment in computational complexity.

Wavelet OFDM-Based Non-orthogonal Multiple Access Downlink Transceiver for Future Radio Access

ABSTRACTTo address the exploding traffic demands for mobile data, non-orthogonal multiple access (NOMA) schemes for resource allocation are considered as one of the potential candidates for future radio access. To this date, NOMA is implemented via orthogonal frequency division multiplexing (OFDM) for waveform shaping, which employs redundancy in the form of cyclic prefix (CP) and induces peak-to-average power ratio () problem. In this paper, wavelet OFDM (WOFDM) is proposed as a waveform shaping scheme for transceivers employing power domain NOMA for resource allocation. Since WOFDM-based systems do not use CP, they can reduce and increase spectral efficiency (SE). Link level performance of power domain NOMA with OFDM and WOFDM as waveform shaping techniques is evaluated in terms of , SE, and computational complexity (CC). In addition, power spectral densities of both transceivers are also analyzed. Simulation results show that NOMA with WOFDM outperforms NOMA with OFD in terms of reduction, out of band emissions reduction, SE, and CC.

Simulation of a Narrowband Power Line Communications System over Medium Voltage

Narrowband Power Line Communications (NB-PLCs) are investigated as an alternative option for transferring low rate smart grid (SG) data via Medium Voltage (MV) power lines. In this framework, two variants of orthogonal frequency division multiplexing are examined, namely Filtered-OFDM (F-OFDM) and Wavelet-OFDM (W-OFDM), in an attempt to determine which of them is capable of transmitting low rate SG data to greater distances over non-branched MV power lines. The reach of NB-PLC signals via MV power lines is estimated, taking into account the transfer function of the relevant PLC channels and noise mechanisms as well as the specific features of the two modulation options under consideration. Simulations show that NB-PLC transmission constitutes a technically feasible and economically affordable option for exchanging low rate data with remote SG nodes dispersed over the MV grid. Moreover, simulations show that F-OFDM allows low rate data transmission to considerably greater distances compared to W-OFDM.

A Wavelet OFDM receiver for baseband power line communications

Wavelet OFDM is one of the medium access techniques adopted by the IEEE P1901 working group for broadband power line communications (PLC). This paper reviews important aspects of baseband physical layer for broadband PLC, such as the scheme of modulation to obtain the transmitter and the characteristics of the recommended prototype filters. It further proposes a viable receiver system compatible with the transmitter and that provides perfect reconstruction characteristics in ideal environments. Furthermore, a procedure to perform the per-subcarrier frequency domain equalization, essential to deal with the power line channel effects at the receiver side, is also addressed. In order to greatly simplify the equalizer design, an efficient fast algorithm with reduced computational complexity is presented. Finally, this study is completed with several computer simulations, considering in-home PLC scenarios, to demonstrate the benefits of the proposed transceiver system.

Design and Development of HiperLAN/2 Physical Layer Model Based Wavelet Signals

HiperLAN (High Performance Radio LAN) is a Wireless LAN standard. It is defined by the European Telecommunications Standards Institute (ETSI). In ETSI the standards are defined by the BRAN project (Broadband Radio Access Networks). In this paper, we improve HIPERLAN/2 based Orthogonal Frequency-Division Multiplexing OFDM, based wavelet signals execution via a MATLAB/ Simulink simulation .These systems provide channel adaptive data rates up to 54 Mb/s (in a 20 MHz channel spacing) in the 5 GHz radio band. For dissimilar channels. MATLAB/ Simulink modeling proved that the performance of wavelet OFDM has a significant degradation in the packet (PDU or PSDU) error rate (PER) compared to based OFDM on Fast Fourier transform (FFT) due to the considerable channel models. With HiperLAN/2 based DWT-OFDM, Carrier-to-Noise Ratio (C/N) development compared to conventional HiperLAN/2 based FFT-OFDM is accomplished. Keywords: HiperLAN/2, OFDM, DWT, IDWT.

웨이블릿 OFDM 시스템과 FD-OFDM 시스템 성능 비교 분석

본 논문에서는 웨이블릿 OFDM (Orthogonal Frequency Division Multiplexing) 및 FD-OFDM(Frequency Diversity OFDM) 시스템과 일반 OFDM 시스템의 성능을 비교 분석 한다. 푸리에 변환에 기반하는 일반 OFDM방식과는 달리 웨이블릿 OFDM 방식은 웨이블릿 변환을 사용하며, CDM (Code Division Multiplexing)과 OFDM의 중간적인 특성을 통해 심볼간 간섭을 효과적으로 제거할 수 있으며 채널간 간섭 역시 최소화 할 수 있다. FD-OFDM 방식의 경우, 각 병렬 브랜치에 입력된 심볼들이 직교 시퀀스로 곱해진 뒤 모든 부반송파에 분배되고, 각 부반송파는 주어진 프레임에서 각 병렬 브랜치의 심볼 조각들의 합의형태로 이루어진 정보를 전달한다. FD-OFDM의 한 부반송파 내에 포함된 모든 심볼들은 직교 시퀀스에 의해 구별되며, 간섭에 강하며 주파수 다이버시티 특성을 가진다는 장점을 지닌다. 협대역 간섭과 하모닉 잡음 환경에서 BER (Bit Error Rate) 성능을 통해 시스템 간 성능 비교 분석을 진행하였으며, 이를 통해 웨이블릿 OFDM과 FD-OFDM의 성능이 일반 OFDM보다 간섭에 대해 강건하고 특히 하모닉 노이즈 환경에서는 웨이블릿 OFDM이 가장 강건한 특성을 보이는 것을 알 수 있다.

An Evaluation of Coded Wavelet for Multicarrier Modulation with OFDM

Orthogonal frequency division multiplexing (OFDM) is pronounced in wireless communication systems. Methods for improving the performance of the OFDM-based systems are mostly sought. A method of doing this involves error correction coding and another, a better multicarrier modulation kernel. In this work, convolutional error correction coding with interleaving is introduced in wavelet multicarrier modulation OFDM system (wavelet-OFDM) to improve the performance of multicarrier systems as the signal traverses the multipath and noisy transmission channels. This is compared with FFT-based multicarrier modulation (FFT-OFDM). Results show that coded wavelet-OFDM saves more than a half of the transmit power than the uncoded wavelet. Also it will be shown that, the interleaved and non-interleaved coded wavelet-OFDM well outperform interleaved coded and non-interleaved coded FFT-OFDM systems respectively.

CIC 필터를 이용한 Wavelet OFDM 설계

현재 매우 빠른 속도로 늘어나고 있는 인터넷 수요를 충족시키기 위하여 새로운 통신 대안이 필요하다. 이런 대안들 중에 하나가 바로 광대역 고속 전력선 통신이다. 전력선 통신은 전력을 전달하는 도체에 신호를 같이 실어 보내는 통신 방법이다. 하지만 전력선을 그대로 사용한다는 단점 때문에 기존의 사용되는 통신 시스템과의 간섭이 발생한다. 이런 간섭을 제거하기 위하여 일반적인 방법으로는 Notch 필터를 주로 사용한다. 반면 다른 방법의 하나로 Wavelet OFDM이 사용된다. 본 논문에서는 Wavelet OFDM에서 사용되는 CMFB구조에 CIC 필터를 적용하여 그 부협의 값을 더욱 낮추어 성능을 높이는 방법을 제안한다. Currently, The new communication system was very important because of the increasing demand for Internet access. One of these alternatives is the PLC. But, Power Line is not suitable for communication. So, electromagnetic wave is generated from Power Line during flow of communication information. And the electromagnetic wave is interfered with Wireless Communication Service using the same frequency range. To eliminate this interference by used Notch tilter. Wavelet OFDM in another way, while one is used. In this paper, Wavelet OFDM CIC filter used in the CMFB structure by applying a further lowering the value of the side-lobe is proposed to improve performance.