Digital Phase Modulation: a Review of Basic Concepts
Total Page:16
File Type:pdf, Size:1020Kb
Load more
Recommended publications
-
UNIT V- SPREAD SPECTRUM MODULATION Introduction
UNIT V- SPREAD SPECTRUM MODULATION Introduction: Initially developed for military applications during II world war, that was less sensitive to intentional interference or jamming by third parties. Spread spectrum technology has blossomed into one of the fundamental building blocks in current and next-generation wireless systems. Problem of radio transmission Narrow band can be wiped out due to interference. To disrupt the communication, the adversary needs to do two things, (a) to detect that a transmission is taking place and (b) to transmit a jamming signal which is designed to confuse the receiver. Solution A spread spectrum system is therefore designed to make these tasks as difficult as possible. Firstly, the transmitted signal should be difficult to detect by an adversary/jammer, i.e., the signal should have a low probability of intercept (LPI). Secondly, the signal should be difficult to disturb with a jamming signal, i.e., the transmitted signal should possess an anti-jamming (AJ) property Remedy spread the narrow band signal into a broad band to protect against interference In a digital communication system the primary resources are Bandwidth and Power. The study of digital communication system deals with efficient utilization of these two resources, but there are situations where it is necessary to sacrifice their efficient utilization in order to meet certain other design objectives. For example to provide a form of secure communication (i.e. the transmitted signal is not easily detected or recognized by unwanted listeners) the bandwidth of the transmitted signal is increased in excess of the minimum bandwidth necessary to transmit it. -
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 -
Protection of Data Transmission Systems from the Influence of Intersymbol Interference of Signals
59 Protection of data transmission systems from the influence of intersymbol interference of signals © Volodymyr Yartsev 1 and © Dmitry Gololobov 2 1 State University of Telecommunications, Kyiv, Ukraine 2 Taras Shevchenko National University of Kyiv, Ukraine [email protected], [email protected] Abstract. The problems of creating a regenerator of an optical system for trans- mitting discrete messages with the aim of protecting against the influence of in- tersymbol interference of signals using the methods of statistical theory for a mixture of probability distributions are considered. A demodulator adaptation model that calculates the weighted sum of 4 samples of the input signal and com- pares the resulting sum with a threshold value has been created and studied. The main operations for adaptation of the regenerator during demodulation of signals distorted by intersymbol interference are assigned under certain transmission conditions, which are formulated as the task of evaluating some parameters of the probability distribution of the mixture. A block diagram of a regenerating optical signal in which an algorithm for digital processing of a mixture is imple- mented is proposed. The analysis is carried out and the requirements for the pa- rameters of the analog-to-digital converter used in the regenerator are deter- mined. The results of modeling digital processing of a discrete test message to verify the process of adaptation of the device to the influence of intersymbol dis- tortions of signals are presented. The block diagram of a digital processing device is substantiated, in which high-speed nodes that perform real-time processing are combined with a microprocessor, which implements an algorithm for adapting the regenerator to specific message transmission conditions. -
Degree Project
Degree project Performance of MLSE over Fading Channels Author: Aftab Ahmad Date: 2013-05-31 Subject: Electrical Engineering Level: Master Level Course code: 5ED06E To my parents, family, siblings, friends and teachers 1 Research is what I'm doing when I don't know what I'm doing1 Wernher Von Braun 1Brown, James Dean, and Theodore S. Rodgers. Doing Second Language Research: An introduction to the theory and practice of second language research for graduate/Master's students in TESOL and Applied Linguistics, and others. OUP Oxford, 2002. 2 Abstract This work examines the performance of a wireless transceiver system. The environment is indoor channel simulated by Rayleigh and Rician fading channels. The modulation scheme implemented is GMSK in the transmitter. In the receiver the Viterbi MLSE is implemented to cancel noise and interference due to the filtering and the channel. The BER against the SNR is analyzed in this thesis. The waterfall curves are compared for two data rates of 1 M bps and 2 Mbps over both the Rayleigh and Rician fading channels. 3 Acknowledgments I would like to thank Prof. Sven Nordebo for his supervision, valuable time and advices and support during this thesis work. I would like to thank Prof. Sven-Eric Sandstr¨om.Iwould also like to thank Sweden and Denmark for giving me an opportunity to study in this education system and experience the Scandinavian life and culture. I must mention my gratitude to Sohail Atif, javvad ur Rehman, Ahmed Zeeshan and all the rest of my buddies that helped me when i most needed it. -
Revision of Wireless Channel
ELEC6214 Advanced Wireless Communications Networks and Systems S Chen Revision of Wireless Channel • Quick recap system block diagram Wireless CODEC MODEM Channel • Previous three lectures looked into wireless mobile channels – To understand mobile communication technologies, one needs a deep understand of mobile communication media – Two main sources of hostility in mobile media are Doppler spread and multipath – Many techniques developed are counter measures for fading and frequency selective – How spatial/angular dimension fits into wireless mobile landscape • Front end of transceiver is Modem, which faces hostile (fading and frequency selective) communication media – Next eight lectures we will have a close look into Modem 57 ELEC6214 Advanced Wireless Communications Networks and Systems S Chen Digital Modulation Overview In Digital Coding and Transmission, we learn schematic of MODEM (modulation and demodulation) • with its basic components: clock carrier pulse b(k) x(k) x(t) s(t) pulse Tx filter bits to modulat. symbols generator GT (f) clock carrier channel recovery recovery GC (f) ^ b(k) x(k)^x(t) ^s(t) ^ symbols sampler/ Rx filter AWGN demodul. + to bits decision GR (f) n(t) The purpose of MODEM: transfer the bit stream at required rate over the communication medium • reliably – Given system bandwidth and power resource 58 ELEC6214 Advanced Wireless Communications Networks and Systems S Chen Constellation Diagram • Digital modulation signal has finite states. This manifests in symbol (message) set: M = {m1, m2, ··· , mM }, where each symbol contains log2 M bits • Or in modulation signal set: S = {s1(t),s2(t), ··· sM (t)}. There is one-to-one relationship between two sets: modulation scheme M S ←→ Q • Example: BPSK, M = 2. -
Bit & Baud Rate
What’s The Difference Between Bit Rate And Baud Rate? Apr. 27, 2012 Lou Frenzel | Electronic Design Serial-data speed is usually stated in terms of bit rate. However, another oft- quoted measure of speed is baud rate. Though the two aren’t the same, similarities exist under some circumstances. This tutorial will make the difference clear. Table Of Contents Background Bit Rate Overhead Baud Rate Multilevel Modulation Why Multiple Bits Per Baud? Baud Rate Examples References Background Most data communications over networks occurs via serial-data transmission. Data bits transmit one at a time over some communications channel, such as a cable or a wireless path. Figure 1 typifies the digital-bit pattern from a computer or some other digital circuit. This data signal is often called the baseband signal. The data switches between two voltage levels, such as +3 V for a binary 1 and +0.2 V for a binary 0. Other binary levels are also used. In the non-return-to-zero (NRZ) format (Fig. 1, again), the signal never goes to zero as like that of return- to-zero (RZ) formatted signals. 1. Non-return to zero (NRZ) is the most common binary data format. Data rate is indicated in bits per second (bits/s). Bit Rate The speed of the data is expressed in bits per second (bits/s or bps). The data rate R is a function of the duration of the bit or bit time (TB) (Fig. 1, again): R = 1/TB Rate is also called channel capacity C. If the bit time is 10 ns, the data rate equals: R = 1/10 x 10–9 = 100 million bits/s This is usually expressed as 100 Mbits/s. -
Application of 4K-QAM, LDPC and OFDM for Gbps Data Rates Over HFC Plant David John Urban Comcast
Application of 4K-QAM, LDPC and OFDM for Gbps Data Rates over HFC Plant David John Urban Comcast Abstract Higher spectral density requires mapping more bits into a symbol at the expense of a This paper describes the application of higher signal to noise ratio (SNR) threshold. 4096-QAM, low density parity check codes The new physical layer will map 12 bits per (LDPC), and orthogonal frequency division symbol on the downstream compared to the 8 multiplexing (OFDM) to transmission over a bits per symbol used in DOCSIS 3.0. 4K- hybrid fiber coaxial cable plant (HFC). These QAM (or 4096-QAM) is a modulation techniques enable data rates of several Gbps. technique that has 4,096 points in the constellation diagram and each point is A complete derivation of the equations mapped to 12 bits. The new physical layer used for log domain sum product LDPC will map 10 bits per symbol using 1024-QAM decoding is provided. The reasons for (or 1K-QAM) on the upstream compared to 6 selecting OFDM and 4K-QAM are described. bits per symbol with 64-QAM used in Analysis of performance in the presence of DOCSIS 3.0. noise taken from field measurements is made. INCREASING SPECTRAL EFFICIENCY INTRODUCTION The three key methods for increasing the A new physical layer is being developed for spectral efficiency of the HFC plant in the transmission of data over a HFC cable plant. new physical layer are LDPC, OFDM and The objective is to increase the HFC plant 4K-QAM. LDPC is a very efficient coding capacity. -
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]. -
Pulse Shape Filtering in Wireless Communication-A Critical Analysis
(IJACSA) International Journal of Advanced Computer Science and Applications, Vol. 2, No.3, March 2011 Pulse Shape Filtering in Wireless Communication-A Critical Analysis A. S Kang Vishal Sharma Assistant Professor, Deptt of Electronics and Assistant Professor, Deptt of Electronics and Communication Engg Communication Engg SSG Panjab University Regional Centre University Institute of Engineering and Technology Hoshiarpur, Punjab, INDIA Panjab University Chandigarh - 160014, INDIA [email protected] [email protected] Abstract—The goal for the Third Generation (3G) of mobile networks. The standard that has emerged is based on ETSI's communications system is to seamlessly integrate a wide variety Universal Mobile Telecommunication System (UMTS) and is of communication services. The rapidly increasing popularity of commonly known as UMTS Terrestrial Radio Access (UTRA) mobile radio services has created a series of technological [1]. The access scheme for UTRA is Direct Sequence Code challenges. One of this is the need for power and spectrally Division Multiple Access (DSCDMA). The information is efficient modulation schemes to meet the spectral requirements of spread over a band of approximately 5 MHz. This wide mobile communications. Pulse shaping plays a crucial role in bandwidth has given rise to the name Wideband CDMA or spectral shaping in the modern wireless communication to reduce WCDMA.[8-9] the spectral bandwidth. Pulse shaping is a spectral processing technique by which fractional out of band power is reduced for The future mobile systems should support multimedia low cost, reliable , power and spectrally efficient mobile radio services. WCDMA systems have higher capacity, better communication systems. It is clear that the pulse shaping filter properties for combating multipath fading, and greater not only reduces inter-symbol interference (ISI), but it also flexibility in providing multimedia services with defferent reduces adjacent channel interference. -
A Measurement Instrument for Fault Diagnosis in Qam-Based Telecommunications
12th IMEKO TC4 International Symposium Electrical Measurements and Instrumentation September 25−27, 2002, Zagreb, Croatia A MEASUREMENT INSTRUMENT FOR FAULT DIAGNOSIS IN QAM-BASED TELECOMMUNICATIONS Pasquale Arpaia(1), Luca De Vito(1,2), Sergio Rapuano(1), Gioacchino Truglia(1,2) (1) Dipartimento di Ingegneria, Università del Sannio, piazza Roma, Benevento, Italy (2) Telsey Telecommunications, viale Mellusi 68, Benevento, Italy Abstract − A method for diagnosing faults in Some techniques for classifying automatically the main communication systems based on QAM (Quadrature faults on QAM modulation via the constellation diagram Amplitude Modulation) modulation scheme is proposed. were proposed. The approach followed in [4] is based on a The most relevant faults affecting this modulation have been Wavelet Network (WN). This method provides very good observed and modelled. Such faults, individually and results on simulated and actual signals. combined, are classified and estimated by analysing the Another method classifies the faults through an image- statistical moments of the received symbols. Simulation and processing approach [5]. The constellation diagram is experimental results of characterisation and validation digitised, then the obtained image is compared with some highlight the practical effectiveness of the proposed method. fault models, by using a correlation method, and a similarity score is provided. Keywords: Fault diagnosis, telecommunication, testing, However, both the WN- and the image processing-based QAM. methods can recognize and eventually measure only the dominating fault, and can not recognize the simultaneous 1. INTRODUCTION presence of several faults. In this paper, a diagnostics method, based on analytical Quadrature Amplitude Modulation (QAM) is an estimation of the statistical moments of the received symbol attractive method for transmitting two data streams in distribution, is proposed for QAM-modulation. -
The Trade-Off Between Transceiver Capacity and Symbol Rate
View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by UCL Discovery The Trade-off Between Transceiver Capacity and Symbol Rate L. Galdino, D. Lavery, Z. Liu, K. Balakier, E. Sillekens, D. Elson, G. Saavedra, R. I. Killey and P. Bayvel Optical Networks Group, Dept. of Electronic & Electrical Engineering, University College London, UK [email protected] Abstract: The achievable throughput using high symbol rate, high order QAM is investigated for the current generation of CMOS-based DAC/ADC. The optimum symbol rate and modula- tion format is found to be 80GBd DP-256QAM, with an 800Gb/s net data rate. OCIS codes: (060.0060) Fiber optics and optical communications; (060.2360) Fiber optics links and subsystems 1. Introduction A key goal when designing a new optical transmission system is to increase the amount of data sent for a given cost. One way to reduce the cost-per-bit is to increase the channel symbol rate, which will maximise the amount of information sent over one channel and reduce the number of transceivers for a given transmission bandwidth. Currently, the upper limit on the available signal-to-noise ratio (SNR), and therefore channel highest achievable information rate (AIR) in a coherent optical transmission system, in the absence of fiber nonlinearity, is bounded by the transceiver subsystems, such as digital-to-analog converter (DAC) and analog to digital converter (ADC). The SNR of an ideal DAC / ADC is defined by the number of bits (N) which sets the quantization noise floor of the device [1]. -
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.