UNIT V- SPREAD SPECTRUM MODULATION Introduction
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CS647: Advanced Topics in Wireless Networks Basics
CS647: Advanced Topics in Wireless Networks Basics of Wireless Transmission Part II Drs. Baruch Awerbuch & Amitabh Mishra Computer Science Department Johns Hopkins University CS 647 2.1 Antenna Gain For a circular reflector antenna G = η ( π D / λ )2 η = net efficiency (depends on the electric field distribution over the antenna aperture, losses such as ohmic heating , typically 0.55) D = diameter, thus, G = η (π D f /c )2, c = λ f (c is speed of light) Example: Antenna with diameter = 2 m, frequency = 6 GHz, wavelength = 0.05 m G = 39.4 dB Frequency = 14 GHz, same diameter, wavelength = 0.021 m G = 46.9 dB * Higher the frequency, higher the gain for the same size antenna CS 647 2.2 Path Loss (Free-space) Definition of path loss LP : Pt LP = , Pr Path Loss in Free-space: 2 2 Lf =(4π d/λ) = (4π f cd/c ) LPF (dB) = 32.45+ 20log10 fc (MHz) + 20log10 d(km), where fc is the carrier frequency This shows greater the fc, more is the loss. CS 647 2.3 Example of Path Loss (Free-space) Path Loss in Free-space 130 120 fc=150MHz (dB) f f =200MHz 110 c f =400MHz 100 c fc=800MHz 90 fc=1000MHz 80 Path Loss L fc=1500MHz 70 0 5 10 15 20 25 30 Distance d (km) CS 647 2.4 Land Propagation The received signal power: G G P P = t r t r L L is the propagation loss in the channel, i.e., L = LP LS LF Fast fading Slow fading (Shadowing) Path loss CS 647 2.5 Propagation Loss Fast Fading (Short-term fading) Slow Fading (Long-term fading) Signal Strength (dB) Path Loss Distance CS 647 2.6 Path Loss (Land Propagation) Simplest Formula: -α Lp = A d where A and -
Novel Joint Chip Sampling and Phase Synchronization Algorithm for Multistandard UMTS Systems
I. J. Communications, Network and System Sciences, 2008, 2, 105-206 Published Online May 2008 in SciRes (http://www.SRPublishing.org/journal/ijcns/). Novel Joint Chip Sampling and Phase Synchronization Algorithm for Multistandard UMTS Systems Youssef SERRESTOU1, Kosai RAOOF2, Joël LIÉNARD2 1 LCIS-INPG, 50 Rue Barthélémy de Laffemas, 26902 cedex, Valence, France 2 GIPSA-LAB, CNRS UMR 5216, 961 Rue de Houille Blanche, 38402 St. Martin d’Hères, France E-mail: [email protected], [email protected] Abstract CDMA Timing and phase offsets tracking remain as one of considerable factors that influence the performances of communication systems. Many algorithms are proposed to solve this problem. In general, these solutions process separately the chip sampling offset and phase rotation. In addition, most of proposed solutions can not assure a compromise between robustness criteria and low complexity for implementation in real time applications. In this paper we present an efficient algorithm for chip sampling and phase synchronization. This algorithm allows estimating and correcting jointly in real time, sampling instant and phase errors. The robustness and the low complexity of this algorithm are evaluated, firstly by simulation and then tested by real experimentation for UMTS standard. Simulation results show that the proposed algorithm provides very efficient compensation for sampling clock offset and phase rotation. A real time implementation is achieved, based on TigerSharc DSP, while using a complete UMTS transmission- reception chain. Experimental results show robustness in real conditions. Keywords: Synchronization, DS-CDMA, UMTS, Joint Estimation, Early-late Loop, Phase Locked Loop 1. Introduction pull-in region of tracking loop [8–11]. -
ATSAMB11XR-ZR Ultra-Low Power Bluetooth Low Energy Sip/Module
ATSAMB11XR/ZR Ultra-Low Power Bluetooth® Low Energy SiP/Module Introduction The ATSAMB11-XR2100A is an ultra-low power Bluetooth Low Energy (BLE) 5.0 System in a Package (SiP) with Integrated MCU, transceiver, modem, MAC, PA, Transmit/Receive (T/R) switch, and Power Management Unit (PMU). It is a standalone Cortex® -M0 applications processor with embedded Flash memory and BLE connectivity. The Bluetooth SIG-qualified Bluetooth Low Energy protocol stack is stored in a dedicated ROM. The firmware includes L2CAP service layer protocols, Security Manager, Attribute protocol (ATT), Generic Attribute Profile (GATT), and the Generic Access Profile (GAP). Additionally, example applications are available for application profiles such as proximity, thermometer, heart rate and blood pressure, and many others. The ATSAMB11-XR2100A provides a compact footprint and various embedded features, such as a 26 MHz crystal oscillator. The ATSAMB11-ZR210CA is a fully certified module that contains the ATSAMB11-XR2100A and all external RF circuitry required, including a ceramic high-gain antenna. The user simply places the module into their PCB and provides power with a 32.768 kHz Real-Time Clock (RTC) or crystal, and an I/O path. Microchip BluSDK Smart offers a comprehensive set of tools and reference applications for several Bluetooth SIG defined profiles and a custom profile. The BluSDK Smart will help the user quickly evaluate, design and develop BLE products with the ATSAMB11-XR2100A and ATSAMB11-ZR210CA. The ATSAMB11-XR2100A and associated ATSAMB11-ZR210CA -
Demodulation of Chaos Phase Modulation Spread Spectrum Signals Using Machine Learning Methods and Its Evaluation for Underwater Acoustic Communication
sensors Article Demodulation of Chaos Phase Modulation Spread Spectrum Signals Using Machine Learning Methods and Its Evaluation for Underwater Acoustic Communication Chao Li 1,2,*, Franck Marzani 3 and Fan Yang 3 1 State Key Laboratory of Acoustics, Institute of Acoustics, Chinese Academy of Sciences, Beijing 100190, China 2 University of Chinese Academy of Sciences, Beijing 100190, China 3 LE2I EA7508, Université Bourgogne Franche-Comté, 21078 Dijon, France; [email protected] (F.M.); [email protected] (F.Y.) * Correspondence: [email protected] Received: 25 September 2018; Accepted: 28 November 2018; Published: 1 December 2018 Abstract: The chaos phase modulation sequences consist of complex sequences with a constant envelope, which has recently been used for direct-sequence spread spectrum underwater acoustic communication. It is considered an ideal spreading code for its benefits in terms of large code resource quantity, nice correlation characteristics and high security. However, demodulating this underwater communication signal is a challenging job due to complex underwater environments. This paper addresses this problem as a target classification task and conceives a machine learning-based demodulation scheme. The proposed solution is implemented and optimized on a multi-core center processing unit (CPU) platform, then evaluated with replay simulation datasets. In the experiments, time variation, multi-path effect, propagation loss and random noise were considered as distortions. According to the results, compared to the reference algorithms, our method has greater reliability with better temporal efficiency performance. Keywords: underwater acoustic communication; direct sequence spread spectrum; chaos phase modulation sequence; partial least square regression; machine learning 1. Introduction The underwater acoustic communication has always been a crucial research topic [1–6]. -
Continuous Phase Modulation with Faster-Than-Nyquist Signaling for Channels with 1-Bit Quantization and Oversampling at the Receiver Rodrigo R
1 Continuous Phase Modulation With Faster-than-Nyquist Signaling for Channels With 1-bit Quantization and Oversampling at the Receiver Rodrigo R. M. de Alencar, Student Member, IEEE, and Lukas T. N. Landau, Member, IEEE, Abstract—Continuous phase modulation (CPM) with 1-bit construction of zero-crossings. The proposed CPM waveform quantization at the receiver is promising in terms of energy conveys the same information per time interval as the common and spectral efficiency. In this study, CPM waveforms with CPFSK while its bandwidth can be the same and even lower. symbol durations significantly shorter than the inverse of the signal bandwidth are proposed, termed faster-than-Nyquist CPM. Referring to the high signaling rate, like it is typical for faster- This configuration provides a better steering of zero-crossings than-Nyquist signaling [9], the novel waveform is termed as compared to conventional CPM. Numerical results confirm a faster-than-Nyquist continuous phase modulation (FTN-CPM). superior performance in terms of BER in comparison with state- Numerical results confirm that the proposed waveform yields of-the-art methods, while having the same spectral efficiency and a significantly reduced bit error rate (BER) as compared to a lower oversampling factor. Moreover, the new waveform can be detected with low-complexity, which yields almost the same the existing methods [7], [6] with at least the same spectral performance as using the BCJR algorithm. efficiency. In addition, FTN-CPM can be detected with low- complexity and with a lower effective oversampling factor in Index Terms—1-bit quantization, oversampling, continuous phase modulation, faster-than-Nyquist signaling. -
Lecture 12 UMTS Universal Mobile Telecom. System
Lecture 12 UMTS Universal Mobile Telecom. System I. Tinnirello Standard & Tech. Evolution I. Tinnirello What is UMTS? UMTS stands for Universal Mobile Telecommunication System It is a part of the ITU “IMT-2000” vision of a global family of 3G mobile communication systems In 1998, at the end of the proposal submission phase, 17 proposals have been presented and accepted main differences due to existing 2G networks UMTS is the European proposal 3GPP group founded to coordinate various proposals and defining a common solution Compatibility guaranteed by multi-standard multi-mode or reconfigurable terminals I. Tinnirello IMT-2000 Variants IMT-2000 includes a family of terrestrial 3G systems based on the following radio interfaces IMT-DS (Direct Spread) UMTS FDD, FOMA (standardized by 3GPP) IMT-MC (Multi Carrier) CDMA 2000, evolution of IS-95 (standardized by 3GPP) IMT-TC (Time Code) UMTS TDD and TD-SCDMA (standardized by 3GPP) I. Tinnirello UMTS: Initial Goals 1. UMTS will be compatible with 2G systems 2. UMTS will use the same frequency spectrum everywhere in the world 3. UMTS will be a global system 4. UMTS will provide multimedia and internet services 5. UMTS will provide QoS guarantees I. Tinnirello IMT-2000 Features Higher data rate through the Air Interface At least 144 kb/s (preferably 384 kb/s) For high mobility (speed up to 250 km/h) subscribers In a wide area coverage (rural outdoor): larger than 1 km At least 384 kb/s (preferably 512 kb/s) For limited mobility (speed up to 120 km/h) subscribers In micro and macro cellular environments (urban/suburban area): max 1 km 2 Mb/s For low mobility (speed up to 10 km/h) subscribers In local coverage areas (indoor and low range outdoor): max 500 m I. -
Digital Phase Modulation: a Review of Basic Concepts
Digital Phase Modulation: A Review of Basic Concepts James E. Gilley Chief Scientist Transcrypt International, Inc. [email protected] August , Introduction The fundamental concept of digital communication is to move digital information from one point to another over an analog channel. More specifically, passband dig- ital communication involves modulating the amplitude, phase or frequency of an analog carrier signal with a baseband information-bearing signal. By definition, fre- quency is the time derivative of phase; therefore, we may generalize phase modula- tion to include frequency modulation. Ordinarily, the carrier frequency is much greater than the symbol rate of the modulation, though this is not always so. In many digital communications systems, the analog carrier is at a radio frequency (RF), hundreds or thousands of MHz, with information symbol rates of many megabaud. In other systems, the carrier may be at an audio frequency, with symbol rates of a few hundred to a few thousand baud. Although this paper primarily relies on examples from the latter case, the concepts are applicable to the former case as well. Given a sinusoidal carrier with frequency: fc , we may express a digitally-modulated passband signal, S(t), as: S(t) A(t)cos(2πf t θ(t)), () = c + where A(t) is a time-varying amplitude modulation and θ(t) is a time-varying phase modulation. For digital phase modulation, we only modulate the phase of the car- rier, θ(t), leaving the amplitude, A(t), constant. BPSK We will begin our discussion of digital phase modulation with a review of the fun- damentals of binary phase shift keying (BPSK), the simplest form of digital phase modulation. -
Bandwidth Scaling of a Phase-Modulated CW Comb Through Four-Wave Mixing in a Silicon Nano-Waveguide
Chalmers Publication Library Bandwidth scaling of a phase-modulated CW comb through four-wave mixing in a silicon nano-waveguide This document has been downloaded from Chalmers Publication Library (CPL). It is the author´s version of a work that was accepted for publication in: Optics Letters (ISSN: 0146-9592) Citation for the published paper: Liu, Y. ; Metcalf, A. ; Torres Company, V. (2014) "Bandwidth scaling of a phase-modulated CW comb through four-wave mixing in a silicon nano-waveguide". Optics Letters, vol. 39(22), pp. 6478-6481. Downloaded from: http://publications.lib.chalmers.se/publication/208731 Notice: Changes introduced as a result of publishing processes such as copy-editing and formatting may not be reflected in this document. For a definitive version of this work, please refer to the published source. Please note that access to the published version might require a subscription. Chalmers Publication Library (CPL) offers the possibility of retrieving research publications produced at Chalmers University of Technology. It covers all types of publications: articles, dissertations, licentiate theses, masters theses, conference papers, reports etc. Since 2006 it is the official tool for Chalmers official publication statistics. To ensure that Chalmers research results are disseminated as widely as possible, an Open Access Policy has been adopted. The CPL service is administrated and maintained by Chalmers Library. (article starts on next page) Bandwidth scaling of a phase-modulated CW comb through four-wave mixing in a silicon nano-waveguide Yang Liu,1* Andrew J. Metcalf,1 Victor Torres Company,1,2 Rui Wu,1,3 Li Fan,1,4 Leo T. -
Module 3: Physical Layer
Module 3: Physical Layer Dr. Natarajan Meghanathan Associate Professor of Computer Science Jackson StateMeghanathan University Jackson, MS 39217 Copyrights Phone: 601-979-3661 E-mail: [email protected] Natarajan 1 Topics • 3.1 Signal Levels: Baud rate and Bit rate • 3.2 Channel Encoding Standards – RS-232 and Manchester Encoding – Delay during transmission • 3.3 Transmission Order of Bits and Bytes • 3.4 Modulation Techniques – Amplitude, Frequency and PhaseMeghanathan modulation • 3.5 Multiplexing Techniques – TDMA, FDMA, StatisticalCopyrights Multiplexing and CDMA All Natarajan 2 Meghanathan Copyrights All Natarajan 3.1 Signal Levels: Baud Rate and Bit Rate Analog and Digital Signals • Data communications deals with two types of information: – analog – digital • An analog signal is characterized by a continuous mathematical function – when the input changes from one value to the next, it does so by movingMeghanathan through all possible intermediate values Copyrights • A digital signal has a fixed set of All valid levels Natarajan – each change consists of an instantaneous move from one valid level to another 4 Digital Signals and Signal Levels • Some systems use voltage to represent digital values – by making a positive voltage correspond to a logical one – and zero voltage correspond to a logical zero • For example, +5 volts can be used for a logical one and 0 volts for a logical zero • If only two levels of voltage are used – each level corresponds to one data bit (0 or 1). • Some physical transmission mechanismsMeghanathan -
Cdma2000-1X EV-DO Wireless Networks: Technology Overview
Technical Brief cdma2000-1x EV-DO Wireless Networks: Technology Overview Cellular networks continue to grow at a rapid pace around the world. In many regions, network operators are bringing cdma2000 1xEV-DO capabilities into commercial service as part of the evolution towards Third-Generation (3G) networks. This technical brief will introduce the reader to cdma2000 1xEV-DO wireless network concepts and will provide understanding and insight into the air interface. In order to assist maintenance personnel in achieving the high data rates promised by EVDO technology, a particular focus will be given to base station forward-link transmissions. We begin with a review of the evolution of cdma2000 1xEV-DO, followed by a description of the forward-link air interface and key RF parameters. We will then discuss some of the testing challenges in cdma2000 1xEV-DO and describe state-of-the-art test tools that can help wireless networks meet quality of service (QoS) goals. cdma2000-1x EV-DO Overview Technical Brief Figure 1. The Evolution of CDMA Technology Evolution of cdma2000 1xEV-DO While cdma2000 1xRTT is capable of data rates of approximately 144 kbps, the higher data rates significantly Code division multiple access (CDMA) is a second-genera- reduce the ability of the CDMA carrier to support voice tion cellular technology that utilizes spread-spectrum traffic channels. As a result, many wireless service providers techniques. CDMA came to market as an alternative to have been reluctant to allow high data rates in 1xRTT and, GSM-based frequency-hopping architectures. Basic CDMA instead, have opted to implement a dedicated carrier using systems deliver approximately 10X the voice capacity of EVDO technology. -
Performance of Coherent Direct Sequence Spread Spectrum
PERFORMANCE OF COHERENT DIRECT SEQUENCE SPREAD SPECTRUM FREQUENCY SHIFT KEYING A thesis presented to the faculty of the Russ College of Engineering and Technology of Ohio University In partial fulfillment of the requirements for the degree Master of Science Sudhir Kumar Sunkara November 2005 This thesis entitled PERFORMANCE OF COHERENT DIRECT SEQUENCE SPREAD SPECTRUM FREQUENCY SHIFT KEYING by SUDHIR KUMAR SUNKARA has been approved for the School of Electrical Engineering and Computer Science and the Russ College of Engineering and Technology by David W. Matolak Associate Professor of Electrical Engineering and Computer Science Dennis Irwin Dean, Russ College of Engineering and Technology SUNKARA, SUDHIR KUMAR. M.S. November 2005. Electrical Engineering and Computer Science Performance of Coherent Direct Sequence Spread Spectrum Frequency Shift Keying (83pp.) Director of Thesis: David W. Matolak We analyze the performance of a multi-user coherently-detected direct sequence spread spectrum frequency shift keying modulated system. Detection is done with respect to an arbitrary user. We derive bit error probability expressions for both synchronous and asynchronous systems. For the synchronous system, we analyze different variations of the system in order to ensure orthogonality. Orthogonality is achieved via both frequency separation and orthogonal codes. In the asynchronous system, orthogonality is achieved only through frequency separation. The channel impairments considered were additive white Gaussian noise and multi-user interference. We then extend this to a Rayleigh fading channel, and provide analytical and simulation results for single user and multi- user cases. We also analyzed the spectral characteristics of these systems. Approved: David W. Matolak Associate Professor of Electrical Engineering and Computer Science Acknowledgements I would like to thank my thesis advisor Dr. -
Amplitude and Frequency/Phase Modulation
Amplitude and Frequency/Phase Modulation I always had difficulties in understanding frequency modulation (FM) and its frequency spectrum. Even for the pure tone modulation, the FM spectrum consists of an infinite number of sidebands whose signs change from one sideband to the next one and whose amplitudes are given by the horrible Bessel functions. I work for Zurich Instruments, a Swiss maker of lock-in amplifiers and it has become a professional inclination to always think in terms of demodulation. The pictorial representation of AM/FM that I like comes with a (pictorial) digression on lock-in demodulation. Reader not interested in demodulation should read only Sect. 1.1.3 and Sect. 1.21 1.1 Lock-in Demodulation as a Change to a Rotating Frame of Reference A lock-in amplifier can find the amplitude AS and phase 'S of an input signal of the type VS(t) = AS cos(!St + 'S): (1.1) by a process called demodulation. The existing literature explains demodulation with the multiplication of the input signal by sine and cosine of the reference phase, also referred to as the in-phase and quadrature of the reference: this reflects the low level implementation of the scheme (it is a real multiplication) but I could never really understand it. I prefer more a different explanation using complex numbers: first I will present the math, then an equivalent pictorial representation. 1.1.1 Demodulation of the Signal: a Mathematical Approach The signal of eq. (1.1) can also be written in the complex plane as the sum of two vectors (phasors), AS each one of length 2