Filter Bank Multicarrier for Massive MIMO

This paper introduces filter bank multicarrier (FBMC) as a potential candidate in the application of massive MIMO communication. It also points out the advantages of FBMC over OFDM (orthogonal frequency division multiplexing) in the application of massive MIMO. The absence of cyclic prefix in FBMC increases the bandwidth efficiency. In addition, FBMC allows carrier aggregation straightforwardly. Self-equalization, a property of FBMC in massive MIMO that is introduced in this paper, has the impact of reducing (i) complexity; (ii) sensitivity to carrier frequency offset (CFO); (iii) peak-to-average power ratio (PAPR); (iv) system latency; and (v) increasing bandwidth efficiency. The numerical results that corroborate these claims are presented.Comment: 7 pages, 6 figure

Multiuser MIMO-OFDM for Next-Generation Wireless Systems

This overview portrays the 40-year evolution of orthogonal frequency division multiplexing (OFDM) research. The amelioration of powerful multicarrier OFDM arrangements with multiple-input multiple-output (MIMO) systems has numerous benefits, which are detailed in this treatise. We continue by highlighting the limitations of conventional detection and channel estimation techniques designed for multiuser MIMO OFDM systems in the so-called rank-deficient scenarios, where the number of users supported or the number of transmit antennas employed exceeds the number of receiver antennas. This is often encountered in practice, unless we limit the number of users granted access in the base station’s or radio port’s coverage area. Following a historical perspective on the associated design problems and their state-of-the-art solutions, the second half of this treatise details a range of classic multiuser detectors (MUDs) designed for MIMO-OFDM systems and characterizes their achievable performance. A further section aims for identifying novel cutting-edge genetic algorithm (GA)-aided detector solutions, which have found numerous applications in wireless communications in recent years. In an effort to stimulate the cross pollination of ideas across the machine learning, optimization, signal processing, and wireless communications research communities, we will review the broadly applicable principles of various GA-assisted optimization techniques, which were recently proposed also for employment inmultiuser MIMO OFDM. In order to stimulate new research, we demonstrate that the family of GA-aided MUDs is capable of achieving a near-optimum performance at the cost of a significantly lower computational complexity than that imposed by their optimum maximum-likelihood (ML) MUD aided counterparts. The paper is concluded by outlining a range of future research options that may find their way into next-generation wireless systems

Multi-user aub-carrier and power allocation algorithm for OFDM/Offset-QAM

In this letter, the multiuser bit and power allocation problem for an Orthogonal Frequency Division Multiplexing (OFDM)/Offset—Quadrature Amplitude Modulation (OQAM) system is investigated. The Signal-to-Interference-plus-Noise Ratio (SINR) and required power expressions for the formulation of the problem in an OFDM/OQAM system are developed. Next, a suboptimal algorithm based on this formulation is proposedThis work supported in part by Project TEC2008-06327-C03-02 and AECIPublicad

Offset-QAM based coherent WDM for spectral efficiency enhancement

Optically multiplexed multi-carrier systems with channel spacing reduced to the symbol rate per carrier are highly susceptible to inter-channel crosstalk, which places stringent requirements for the specifications of system components and hinders the use of high-level formats. In this paper, we investigate the performance benefits of using offset 4-, 16-, and 64-quadrature amplitude modulation (QAM) in coherent wavelength division multiplexing (CoWDM). We compare this system with recently reported Nyquist WDM and no-guard-interval optical coherent orthogonal frequency division multiplexing, and show that the presented system greatly relaxes the requirements for device specifications and enhances the spectral efficiency by enabling the use of high-level QAM. The achieved performance can approach the theoretical limits using practical components

An Investigation into the Implementation and Performance of Spectrally Shaped Orthogonal Frequency Division Multiplex

Orthogonal Frequency Division Multiplex (OFDM) is a flexible, robust multi-carrier modulation scheme. The orthogonal spectral shaping and spacing of OFDM sub-carriers ensure that their spectra can be over-lapped without leading to undesirable inter-carrier interference. Conventional OFDM systems have non-band limited Sinc(x) shaped subcarrier spectra. An alternative form of OFDM, referred to hereafter as Spectrally Shaped OFDM, employs band limited Nyquist shaped sub-carrier spectra. The research described in this thesis investigates the strengths and weaknesses of Spectrally Shaped OFDM as a potential modulation scheme for future mobile radio applications. From this research a novel Digital Signal Processing architecture for modulating and demodulating Spectrally Shaped OFDM sub-carriers has been derived which exploits the combination of a complex Discrete Fourier Transform (DFT) and PolyPhase Network (PPN) filter. This architecture is shown to significantly reduce the minimum number of computations required per symbol compared to previous designs. Using a custom coded computer simulation, the effects of varying the key parameters of the novel architecture's PolyPhase Filter (PPN) filter an the overall system complexity, spectral performance and system signal-to-distortion have been extensively studied. From these studies it is shown that compared to similar conventional OFDM systems, Spectrally Shaped OFDM systems possess superior out-of-band spectral qualities but significantly worse Peak-to-Average-Power-Ratio (PAPR) envelope performance. lt is also shown that the absolute value of the end PPN filter coefficients (dependent on the roll-off factor of the sub-carrier spectral shaping) dictate the system signal-to-distortion ratio when no time-domain windowing of the PPN filter coefficients is applied. Finally the effects of a both time and frequency selective fast fading channels on the modulation scheme's uncoded Bit Error Rate (BER) versus Signal-to-Noise (SNR) performance are simulated. The results obtained indicate that Spectrally Shaped OFDM is more robust (lower BER) to frequency-selective fading than time-selective fading

Design and FPGA Implementation of OFDM System with Channel Estimation and Synchronization

In wireless and mobile communications, multipath fading severely degrades the quality of information exchange. The orthogonal frequency division multiplexing (OFDM) technology is able to provide a high transmission data rate with enhanced communication performance at a relatively small bandwidth cost, together with proper estimation and compensation of channel effects. Therefore, it has been widely applied in many wireless and mobile networks, especially for the state-of-the-art communication standards. The unique structure of OFDM signals and the application of discrete Fourier transform (DFT) algorithm have significantly simplified the digital implementation of OFDM system. Among different kinds of implementations, field programmable gate array (FPGA) is a very cost-effective and highly flexible solution, which provides superior system performance and enables easy system upgrade. In this thesis, a baseband OFDM system with channel estimation and timing synchronization is designed and implemented using the FPGA technology. The system is prototyped based on the IEEE 802.11a standard and the signals is transmitted and received using a bandwidth of 20 MHz. With the help of the quadrature phase shift keying (QPSK) modulation, the system can achieve a throughput of 24 Mbps. Moreover, the least squares (LS) algorithm is implemented and the estimation of a frequency-selective fading channel is demonstrated. For the coarse estimation of timing, a modified maximum-normalized correlation (MNC) scheme is investigated and implemented. Starting from theoretical study, this thesis in detail describes the system design and verification on the basis of both MATLAB simulation and hardware implementation. Bit error rate (BER) verses bit energy to noise spectral density (Eb/N0) is presented in the case of different channels. In the meanwhile, comparison is made between the simulation and implementation results, which verifies system performance from the system level to the register transfer level (RTL). First of all, the entire system is modeled in MATLAB and a floating-point model is established. Then, the fixed-point model is created with the help of Xilinx’s System Generator for DSP (XSG) and Simulink. Subsequently, the system is synthesized and implemented within Xilinx’s Integrated Software Environment (ISE) tools and targeted to Xilinx Virtex-5 board. What is more, a hardware co-simulation is devised to reduce the processing time while calculating the BER for the fixed-point model. The present thesis is an initial work on the implementation part of an collaborative research and development (CRD) project of the Natural Sciences and Engineering Research Council of Canada (NSERC) sponsored by the WiTel Technologies, Ontario. It is the first and foremost step for further investigation of designing innovative channel estimation techniques towards applications in the fourth generation (4G) mobile communication systems

Investigation of coding and equalization for the digital HDTV terrestrial broadcast channel

Includes bibliographical references (p. 241-248).Supported by the Advanced Telecommunications Research Program.Julien J. Nicolas

ヘンパ チョッコウセイ ヲ モチイタ コウソク チョッコウ シュウハスウ タジュウ ディジタル ヘンチョウ ホウシキ ニカンスル ケンキュウ

博士論文/博士(工学)/平成11年3月24日授与/奈良先端科学技術大学院大学授