This document discusses different types of data (analog and digital) and communication methods. It covers topics like:
- Analog data is represented as continuous waves while digital uses discrete ON/OFF pulses.
- Analog transmission has lower maintenance costs but higher transmission costs, while digital is the opposite.
- Channels can be ideal, analog, or digital in nature. Digital channels carry bits at a rate called the bit rate.
- Transmission modes include simplex, half-duplex, and full-duplex.
- Media can be guided (using cables) or unguided (using radio waves). Examples of each are provided.
Analogue and digital signals, as well as various communication media, were discussed. Analogue signals are continuous over time and value, while digital signals change between discrete high and low values. Common communication media include coaxial cable, twisted pair cable, fiber optic cable, microwave, and satellite. Each media has advantages and disadvantages for different applications.
A Level Physics - Telecommunications - A Basic Introduction
Sound waves
Microphones
Receivers and transmitters
Amplitude modulation (am)
Frequency modulation (fm)
MICROWAVES
Satellite Communication
Optical fibers
Attenuation
The Public Switched Telephone Network
Diversity Techniques in mobile communicationsDiwaker Pant
The document discusses diversity techniques in wireless communication. It introduces different types of diversity including frequency diversity and time diversity. Frequency diversity involves transmitting the same information over multiple carrier frequencies separated by more than the coherence bandwidth. Time diversity involves repeated transmission of information with time spacing exceeding the channel coherence time. The document provides examples of how techniques like frequency division multiplexing and rake receivers implement frequency and time diversity respectively.
Satellite communication analog and digital signalsAjay Kumar
This document discusses various sources of information and signals used in satellite communication, their characteristics, and applications. It describes primary information sources like speech, audio, video, and data. It then covers analog signals, including different types of analog signals and modulation schemes used. The document also discusses digital signals, examples of encoding digital data, and various digital modulation schemes. It provides advantages and disadvantages of both analog and digital signals.
RF fundamentals document discusses key concepts in radio frequency communications including:
- Communication requires sending, receiving, and processing information via electric means over a physical channel.
- A transmitter modifies a message signal for efficient transmission over the channel via modulation. The receiver demodulates the signal to recover the original message.
- Modulation involves varying parameters of a carrier wave like amplitude, frequency, or phase according to the message signal. This allows for efficient transmission and separation of multiple signals.
- Demodulation is the reverse process of modulation to recover the original message signal from the modulated wave.
- There are different types of modulation including amplitude modulation, frequency modulation, phase modulation, and digital modulation techniques
This document provides an overview of radio frequency (RF) basics for non-RF engineers. It defines common RF terms like dBm and discusses electromagnetic spectrum allocation. It describes the basic building blocks of RF systems including transmitters, receivers, modulation methods, and system types. Key topics covered include amplitude shift keying, frequency shift keying, and phase shift keying digital modulation techniques. The document also reviews RF parameters and measurement equipment.
Introduction to RF & Wireless - Part 2Carl Weisman
The document provides an overview of Module 2 of a two-day seminar on radio frequency (RF) and wireless hardware. Module 2 focuses on RF hardware building blocks, including transmitters, receivers, antennas, amplifiers, filters, mixers and sources. It describes the basic functions and characteristics of antennas and amplifiers, the two main building blocks covered in this module. Key antenna topics include antenna patterns, gain, polarization and smart antennas. Key amplifier topics include power gain, linearity, noise figure and output power.
Upon completion of this chapter, students will be able to:
- Understand the key elements of a communication system including information sources, transmitters, transmission mediums, receivers, and destination equipment.
- Comprehend core concepts such as signals, modulation, noise, interference, and frequency spectrums.
- Learn about various communication system types including radio, broadcasting, and computer networks.
Analogue and digital signals, as well as various communication media, were discussed. Analogue signals are continuous over time and value, while digital signals change between discrete high and low values. Common communication media include coaxial cable, twisted pair cable, fiber optic cable, microwave, and satellite. Each media has advantages and disadvantages for different applications.
A Level Physics - Telecommunications - A Basic Introduction
Sound waves
Microphones
Receivers and transmitters
Amplitude modulation (am)
Frequency modulation (fm)
MICROWAVES
Satellite Communication
Optical fibers
Attenuation
The Public Switched Telephone Network
Diversity Techniques in mobile communicationsDiwaker Pant
The document discusses diversity techniques in wireless communication. It introduces different types of diversity including frequency diversity and time diversity. Frequency diversity involves transmitting the same information over multiple carrier frequencies separated by more than the coherence bandwidth. Time diversity involves repeated transmission of information with time spacing exceeding the channel coherence time. The document provides examples of how techniques like frequency division multiplexing and rake receivers implement frequency and time diversity respectively.
Satellite communication analog and digital signalsAjay Kumar
This document discusses various sources of information and signals used in satellite communication, their characteristics, and applications. It describes primary information sources like speech, audio, video, and data. It then covers analog signals, including different types of analog signals and modulation schemes used. The document also discusses digital signals, examples of encoding digital data, and various digital modulation schemes. It provides advantages and disadvantages of both analog and digital signals.
RF fundamentals document discusses key concepts in radio frequency communications including:
- Communication requires sending, receiving, and processing information via electric means over a physical channel.
- A transmitter modifies a message signal for efficient transmission over the channel via modulation. The receiver demodulates the signal to recover the original message.
- Modulation involves varying parameters of a carrier wave like amplitude, frequency, or phase according to the message signal. This allows for efficient transmission and separation of multiple signals.
- Demodulation is the reverse process of modulation to recover the original message signal from the modulated wave.
- There are different types of modulation including amplitude modulation, frequency modulation, phase modulation, and digital modulation techniques
This document provides an overview of radio frequency (RF) basics for non-RF engineers. It defines common RF terms like dBm and discusses electromagnetic spectrum allocation. It describes the basic building blocks of RF systems including transmitters, receivers, modulation methods, and system types. Key topics covered include amplitude shift keying, frequency shift keying, and phase shift keying digital modulation techniques. The document also reviews RF parameters and measurement equipment.
Introduction to RF & Wireless - Part 2Carl Weisman
The document provides an overview of Module 2 of a two-day seminar on radio frequency (RF) and wireless hardware. Module 2 focuses on RF hardware building blocks, including transmitters, receivers, antennas, amplifiers, filters, mixers and sources. It describes the basic functions and characteristics of antennas and amplifiers, the two main building blocks covered in this module. Key antenna topics include antenna patterns, gain, polarization and smart antennas. Key amplifier topics include power gain, linearity, noise figure and output power.
Upon completion of this chapter, students will be able to:
- Understand the key elements of a communication system including information sources, transmitters, transmission mediums, receivers, and destination equipment.
- Comprehend core concepts such as signals, modulation, noise, interference, and frequency spectrums.
- Learn about various communication system types including radio, broadcasting, and computer networks.
This document provides an overview of principles of communication. It discusses key components of a communication system including the transmitter, communication channel, and receiver. It describes different forms of modulation used in analog and digital communication systems, including amplitude modulation, frequency modulation, and pulse modulation. It also discusses antennas, communication channels, receivers, and applications of communication systems like data transmission, fax, radio, television, and satellite communication.
This document provides information about microwave technology including:
1) Microwave frequencies range from 300MHz to 300GHz but communication uses 3GHz to 30GHz. Microwaves propagate as plane waves with electric and magnetic fields perpendicular to the direction of travel.
2) Common microwave link frequencies are listed between 2GHz and 38GHz. Microwave links can carry PDH, SDH, Ethernet and combinations of these protocols.
3) Microwave propagation is affected by the atmosphere through refraction, reflection, absorption and diffusion. The ground also impacts propagation through diffraction and reflection. Diversity techniques like space, frequency and polarization can overcome signal losses.
This document provides an overview of key concepts in radio frequency (RF) technology for wireless communication systems. It defines terms like dBm for measuring power, and modulation schemes like amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK) for encoding digital signals onto radio carriers. The document also outlines considerations for selecting an appropriate low-power wireless solution, including radio spectrum and network types.
This document discusses radio frequency (RF) basics, including:
1) RF signals are characterized by their frequency and amplitude. Frequency is measured in Hertz and refers to the number of cycles per second. Amplitude is measured in Volts and relates to the strength of the signal.
2) Using decibels (dB) to express power ratios along an RF chain allows gains and losses to be simply added or subtracted, rather than multiplying and dividing raw power values.
3) As an example, the power received (Prec) at the end of a chain with a transmitter, amplifier, and two cables can be calculated by adding the transmitter power (Ptransm) to the gain of the amplifier and subtract
RF Basics & Getting Started Guide by AnarenAnaren, Inc.
This document provides an overview of parameters and considerations for selecting a low-power wireless solution. It highlights products from Anaren's Integrated Radio module line, including how they fit into a typical low-power design. Development tools and evaluation modules are also discussed. Stack considerations cover aspects like application and protocol design freedom across various standards.
This document provides an outline for a course on communication systems. It covers several key topics:
1) The different types of modulation techniques used in analog and digital communication systems including amplitude, frequency, phase, and pulse modulation.
2) The basic components and functioning of a communication system including information sources, encoding, transmission over a channel, reception and decoding.
3) Characteristics of communication channels such as bandwidth, transmitted power, and how these resources are used efficiently.
4) Differences between analog and digital communication systems and some advantages of digital systems.
Digital Communication System
Communication Channels
AWGN: Universal channel model
Band Limited Channel: Channel BW <Signal BW, ISI
Fading Channel: multipath waves
Basic Modulation Methods
Criteria for choosing Modulation Schemes
Power Efficiency: Required Eb/N for certain error probability over AWGN channel
Bandwidth Efficiency: no. of bits per second that can be transmitted on system bandwidth.
System Complexity: Amount of circuit involved and complexity
System Performance Parameters
Average SNR
Outage Probability: instantaneous prob. Exceed certain limit
Average BEP
Amount of Fading/severity of fading
Average Outage duration: O/P SNR fall below certain SNR
This document outlines an RF fundamentals course taught in 3 modules. Module 1 covers basics of RF including frequency, amplitude, wavelength, phase, and polarization. It also discusses transmission line fundamentals. Module 2 discusses RF communication systems, modulation techniques, and RF design. Module 3 covers wireless technologies like Bluetooth, WiFi, and cellular standards. The course provides assignments on topics like wavelength calculation and transmission line speed calculation in different materials. It also explains dBm calculations and concepts like signal to noise ratio, gain and loss.
Ripple control is a power line communication method used by electric utilities to remotely control loads like water heaters and street lights. It works by superimposing a coded control signal onto the 50Hz voltage waveform.
While smart meters allow for two-way communication, ripple control still provides utilities faster load control during emergencies compared to wireless options. Grid sensing uses sensor networks to monitor the electric grid in real-time for issues like equipment failures. Load management through ripple control involves directly or indirectly controlling loads like water heaters during peak periods to reduce demand. Attenuation can cause receiving relays not to operate loads as intended, while amplification can cause interference in customer equipment. Utilities mitigate inappropriate signal levels by
This document summarizes the performance measurements taken on a 40-channel 10G DWDM system operated by Bharath Sanchar Nigam Limited in India. The key findings were:
1. Optical power levels were measured for each channel at different points in the system. Some channels showed power levels indicating a fault in the respective fiber cable.
2. Parameters like noise figure, gain, polarization mode dispersion and dispersion were analyzed to identify limitations and suggest improvements to optimize the system.
3. Nonlinear impairments like four-wave mixing, self-phase modulation and stimulated Raman/Brillouin scattering were also evaluated to determine their impact based on number of channels, channel power, and fiber properties
Understanding RF Fundamentals and the Radio Design of Wireless NetworksCisco Mobility
The document discusses an advanced session that focuses on understanding radio frequency fundamentals and design of wireless networks, covering topics like 802.11 radio hardware, antenna basics, interpreting antenna patterns, distributed antenna systems, survey tools, and lessons learned from challenging wireless deployments in various environments. The session aims to provide a deep-dive understanding of the radio frequency aspects of wireless LAN design and deployment that are often overlooked. Certain topics related to security, density, location services, and management will not be covered in this session.
The document describes information and energy control systems. It discusses block diagrams of typical information systems like audio and process monitoring systems. It explains how electrical signals convey system information and the functions of system components like transducers, amplifiers, oscillators, analog to digital converters and digital to analog converters. It also discusses the effects of noise on systems and how system output is determined from a given input.
Modulation is the process of encoding information from a message source for transmission. It involves translating a baseband message signal to a bandpass signal at higher frequencies. Modulation can be done by varying the amplitude, phase, or frequency of a carrier signal based on the message signal. Digital modulation uses a discrete time sequence of symbols to represent bits of information, allowing for robustness and enabling techniques like error correction coding. The choice of digital modulation influences factors like bit error rate, power efficiency, bandwidth occupancy, and performance in fading channels.
This presentation demonstrate:
- Different RF receiver architectures.
- Basics of Multi-Standard receivers.
- How to select receiver's specifications from the selected standard.
- Subsampling basics.
This document discusses key concepts in data transmission including:
1) Data transmission involves transmitting data between a transmitter and receiver via some medium, which can be guided (e.g. cable) or unguided/wireless (e.g. air).
2) Transmission can be direct point-to-point, multi-point involving more than two devices, or simplex, half-duplex, or full-duplex depending on direction of communication.
3) Digital signals maintain constant levels that change abruptly, while analog signals vary smoothly over time. Periodic signals have a repeated pattern while aperiodic signals do not.
4) Transmission is impaired by attenuation, delay distortion, noise,
Signals and Systems
What is a signal?
Signal Basics
Analog / Digital Signals
Real vs Complex
Periodic vs. Aperiodic
Bounded vs. Unbounded
Causal vs. Noncausal
Even vs. Odd
Power vs. Energy
This presentation deals with topics such as Electromagnetic Spectrum, Wireless Propagation, Signals, Signal propagation effects, Spread spectrum and cellular systems.
ECE 618 covers topics related to mobile and wireless communications including frequencies, signals, antennas, and multiplexing techniques. The course discusses frequency ranges used for mobile communication and how signals are represented. It also examines antenna types including isotropic radiators, dipoles, directed, and sectorized antennas. The document outlines multiplexing methods such as FDM, TDM, CDM and modulation schemes including ASK, FSK, PSK and their advantages.
Wireless Communication and Networking by WilliamStallings Chap2Senthil Kanth
Hai I'm Senthilkanth, doing MCA in Mepco Schlenk Engineering College..
The following presentation covers topic called Wireless Communication and Networking
by WilliamStallings for BSc CS, BCA, MSc CS, MCA, ME students.Make use of it.
Wireless Communication and Networking
by WilliamStallings Chapter : 2Transmission Fundamentals
Chapter 2
Electromagnetic Signal
Function of time
Can also be expressed as a function of frequency
Signal consists of components of different frequencies
Time-Domain Concepts
Analog signal - signal intensity varies in a smooth fashion over time
No breaks or discontinuities in the signal
Digital signal - signal intensity maintains a constant level for some period of time and then changes to another constant level
Periodic signal - analog or digital signal pattern that repeats over time
s(t +T ) = s(t ) -¥< t < +¥
where T is the period of the signal
Time-Domain Concepts
Aperiodic signal - analog or digital signal pattern that doesn't repeat over time
Peak amplitude (A) - maximum value or strength of the signal over time; typically measured in volts
Frequency (f )
Rate, in cycles per second, or Hertz (Hz) at which the signal repeats
Time-Domain Concepts
Period (T ) - amount of time it takes for one repetition of the signal
T = 1/f
Phase () - measure of the relative position in time within a single period of a signal
Wavelength () - distance occupied by a single cycle of the signal
Or, the distance between two points of corresponding phase of two consecutive cycles
Sine Wave Parameters
General sine wave
s(t ) = A sin(2ft + )
Figure 2.3 shows the effect of varying each of the three parameters
(a) A = 1, f = 1 Hz, = 0; thus T = 1s
(b) Reduced peak amplitude; A=0.5
(c) Increased frequency; f = 2, thus T = ½
(d) Phase shift; = /4 radians (45 degrees)
note: 2 radians = 360° = 1 period
Sine Wave Parameters
Time vs. Distance
When the horizontal axis is time, as in Figure 2.3, graphs display the value of a signal at a given point in space as a function of time
With the horizontal axis in space, graphs display the value of a signal at a given point in time as a function of distance
At a particular instant of time, the intensity of the signal varies as a function of distance from the source
Frequency-Domain Concepts
Fundamental frequency - when all frequency components of a signal are integer multiples of one frequency, it’s referred to as the fundamental frequency
Spectrum - range of frequencies that a signal contains
Absolute bandwidth - width of the spectrum of a signal
Effective bandwidth (or just bandwidth) - narrow band of frequencies that most of the signal’s energy is contained in
Frequency-Domain Concepts
Any electromagnetic signal can be shown to consist of a collection of periodic analog signals (sine waves) at different amplitudes, frequencies, and phases
The period of the total signal is equal to the period of the fundamenta
CYWUSB6935: WirelessUSB LR 2.4-GHz DSSS Radio SoCPremier Farnell
The document introduces the WirelessUSB technology and the CYWUSB693 WirelessUSB transceiver chip. It provides an overview of WirelessUSB and how it compares to other wireless technologies like Bluetooth and Zigbee. It then describes the key features of the CYWUSB6935 chip such as its 2.4GHz radio, data throughput, and integrated components. Finally, it outlines some potential applications for WirelessUSB technology and provides a functional description and block diagram of the CYWUSB6935 chip.
Modems convert digital data to analog signals and vice versa, allowing digital devices like computers to communicate over analog networks. Remote access servers (RAS) terminate connections from remote users and prepare data for transmission over packet networks, enabling services like remote access, VoIP, and virtual private networks. However, current RAS equipment has limitations in channel density, power consumption, and processing capability that will reduce their usefulness for newer applications.
This document provides an overview of principles of communication. It discusses key components of a communication system including the transmitter, communication channel, and receiver. It describes different forms of modulation used in analog and digital communication systems, including amplitude modulation, frequency modulation, and pulse modulation. It also discusses antennas, communication channels, receivers, and applications of communication systems like data transmission, fax, radio, television, and satellite communication.
This document provides information about microwave technology including:
1) Microwave frequencies range from 300MHz to 300GHz but communication uses 3GHz to 30GHz. Microwaves propagate as plane waves with electric and magnetic fields perpendicular to the direction of travel.
2) Common microwave link frequencies are listed between 2GHz and 38GHz. Microwave links can carry PDH, SDH, Ethernet and combinations of these protocols.
3) Microwave propagation is affected by the atmosphere through refraction, reflection, absorption and diffusion. The ground also impacts propagation through diffraction and reflection. Diversity techniques like space, frequency and polarization can overcome signal losses.
This document provides an overview of key concepts in radio frequency (RF) technology for wireless communication systems. It defines terms like dBm for measuring power, and modulation schemes like amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK) for encoding digital signals onto radio carriers. The document also outlines considerations for selecting an appropriate low-power wireless solution, including radio spectrum and network types.
This document discusses radio frequency (RF) basics, including:
1) RF signals are characterized by their frequency and amplitude. Frequency is measured in Hertz and refers to the number of cycles per second. Amplitude is measured in Volts and relates to the strength of the signal.
2) Using decibels (dB) to express power ratios along an RF chain allows gains and losses to be simply added or subtracted, rather than multiplying and dividing raw power values.
3) As an example, the power received (Prec) at the end of a chain with a transmitter, amplifier, and two cables can be calculated by adding the transmitter power (Ptransm) to the gain of the amplifier and subtract
RF Basics & Getting Started Guide by AnarenAnaren, Inc.
This document provides an overview of parameters and considerations for selecting a low-power wireless solution. It highlights products from Anaren's Integrated Radio module line, including how they fit into a typical low-power design. Development tools and evaluation modules are also discussed. Stack considerations cover aspects like application and protocol design freedom across various standards.
This document provides an outline for a course on communication systems. It covers several key topics:
1) The different types of modulation techniques used in analog and digital communication systems including amplitude, frequency, phase, and pulse modulation.
2) The basic components and functioning of a communication system including information sources, encoding, transmission over a channel, reception and decoding.
3) Characteristics of communication channels such as bandwidth, transmitted power, and how these resources are used efficiently.
4) Differences between analog and digital communication systems and some advantages of digital systems.
Digital Communication System
Communication Channels
AWGN: Universal channel model
Band Limited Channel: Channel BW <Signal BW, ISI
Fading Channel: multipath waves
Basic Modulation Methods
Criteria for choosing Modulation Schemes
Power Efficiency: Required Eb/N for certain error probability over AWGN channel
Bandwidth Efficiency: no. of bits per second that can be transmitted on system bandwidth.
System Complexity: Amount of circuit involved and complexity
System Performance Parameters
Average SNR
Outage Probability: instantaneous prob. Exceed certain limit
Average BEP
Amount of Fading/severity of fading
Average Outage duration: O/P SNR fall below certain SNR
This document outlines an RF fundamentals course taught in 3 modules. Module 1 covers basics of RF including frequency, amplitude, wavelength, phase, and polarization. It also discusses transmission line fundamentals. Module 2 discusses RF communication systems, modulation techniques, and RF design. Module 3 covers wireless technologies like Bluetooth, WiFi, and cellular standards. The course provides assignments on topics like wavelength calculation and transmission line speed calculation in different materials. It also explains dBm calculations and concepts like signal to noise ratio, gain and loss.
Ripple control is a power line communication method used by electric utilities to remotely control loads like water heaters and street lights. It works by superimposing a coded control signal onto the 50Hz voltage waveform.
While smart meters allow for two-way communication, ripple control still provides utilities faster load control during emergencies compared to wireless options. Grid sensing uses sensor networks to monitor the electric grid in real-time for issues like equipment failures. Load management through ripple control involves directly or indirectly controlling loads like water heaters during peak periods to reduce demand. Attenuation can cause receiving relays not to operate loads as intended, while amplification can cause interference in customer equipment. Utilities mitigate inappropriate signal levels by
This document summarizes the performance measurements taken on a 40-channel 10G DWDM system operated by Bharath Sanchar Nigam Limited in India. The key findings were:
1. Optical power levels were measured for each channel at different points in the system. Some channels showed power levels indicating a fault in the respective fiber cable.
2. Parameters like noise figure, gain, polarization mode dispersion and dispersion were analyzed to identify limitations and suggest improvements to optimize the system.
3. Nonlinear impairments like four-wave mixing, self-phase modulation and stimulated Raman/Brillouin scattering were also evaluated to determine their impact based on number of channels, channel power, and fiber properties
Understanding RF Fundamentals and the Radio Design of Wireless NetworksCisco Mobility
The document discusses an advanced session that focuses on understanding radio frequency fundamentals and design of wireless networks, covering topics like 802.11 radio hardware, antenna basics, interpreting antenna patterns, distributed antenna systems, survey tools, and lessons learned from challenging wireless deployments in various environments. The session aims to provide a deep-dive understanding of the radio frequency aspects of wireless LAN design and deployment that are often overlooked. Certain topics related to security, density, location services, and management will not be covered in this session.
The document describes information and energy control systems. It discusses block diagrams of typical information systems like audio and process monitoring systems. It explains how electrical signals convey system information and the functions of system components like transducers, amplifiers, oscillators, analog to digital converters and digital to analog converters. It also discusses the effects of noise on systems and how system output is determined from a given input.
Modulation is the process of encoding information from a message source for transmission. It involves translating a baseband message signal to a bandpass signal at higher frequencies. Modulation can be done by varying the amplitude, phase, or frequency of a carrier signal based on the message signal. Digital modulation uses a discrete time sequence of symbols to represent bits of information, allowing for robustness and enabling techniques like error correction coding. The choice of digital modulation influences factors like bit error rate, power efficiency, bandwidth occupancy, and performance in fading channels.
This presentation demonstrate:
- Different RF receiver architectures.
- Basics of Multi-Standard receivers.
- How to select receiver's specifications from the selected standard.
- Subsampling basics.
This document discusses key concepts in data transmission including:
1) Data transmission involves transmitting data between a transmitter and receiver via some medium, which can be guided (e.g. cable) or unguided/wireless (e.g. air).
2) Transmission can be direct point-to-point, multi-point involving more than two devices, or simplex, half-duplex, or full-duplex depending on direction of communication.
3) Digital signals maintain constant levels that change abruptly, while analog signals vary smoothly over time. Periodic signals have a repeated pattern while aperiodic signals do not.
4) Transmission is impaired by attenuation, delay distortion, noise,
Signals and Systems
What is a signal?
Signal Basics
Analog / Digital Signals
Real vs Complex
Periodic vs. Aperiodic
Bounded vs. Unbounded
Causal vs. Noncausal
Even vs. Odd
Power vs. Energy
This presentation deals with topics such as Electromagnetic Spectrum, Wireless Propagation, Signals, Signal propagation effects, Spread spectrum and cellular systems.
ECE 618 covers topics related to mobile and wireless communications including frequencies, signals, antennas, and multiplexing techniques. The course discusses frequency ranges used for mobile communication and how signals are represented. It also examines antenna types including isotropic radiators, dipoles, directed, and sectorized antennas. The document outlines multiplexing methods such as FDM, TDM, CDM and modulation schemes including ASK, FSK, PSK and their advantages.
Wireless Communication and Networking by WilliamStallings Chap2Senthil Kanth
Hai I'm Senthilkanth, doing MCA in Mepco Schlenk Engineering College..
The following presentation covers topic called Wireless Communication and Networking
by WilliamStallings for BSc CS, BCA, MSc CS, MCA, ME students.Make use of it.
Wireless Communication and Networking
by WilliamStallings Chapter : 2Transmission Fundamentals
Chapter 2
Electromagnetic Signal
Function of time
Can also be expressed as a function of frequency
Signal consists of components of different frequencies
Time-Domain Concepts
Analog signal - signal intensity varies in a smooth fashion over time
No breaks or discontinuities in the signal
Digital signal - signal intensity maintains a constant level for some period of time and then changes to another constant level
Periodic signal - analog or digital signal pattern that repeats over time
s(t +T ) = s(t ) -¥< t < +¥
where T is the period of the signal
Time-Domain Concepts
Aperiodic signal - analog or digital signal pattern that doesn't repeat over time
Peak amplitude (A) - maximum value or strength of the signal over time; typically measured in volts
Frequency (f )
Rate, in cycles per second, or Hertz (Hz) at which the signal repeats
Time-Domain Concepts
Period (T ) - amount of time it takes for one repetition of the signal
T = 1/f
Phase () - measure of the relative position in time within a single period of a signal
Wavelength () - distance occupied by a single cycle of the signal
Or, the distance between two points of corresponding phase of two consecutive cycles
Sine Wave Parameters
General sine wave
s(t ) = A sin(2ft + )
Figure 2.3 shows the effect of varying each of the three parameters
(a) A = 1, f = 1 Hz, = 0; thus T = 1s
(b) Reduced peak amplitude; A=0.5
(c) Increased frequency; f = 2, thus T = ½
(d) Phase shift; = /4 radians (45 degrees)
note: 2 radians = 360° = 1 period
Sine Wave Parameters
Time vs. Distance
When the horizontal axis is time, as in Figure 2.3, graphs display the value of a signal at a given point in space as a function of time
With the horizontal axis in space, graphs display the value of a signal at a given point in time as a function of distance
At a particular instant of time, the intensity of the signal varies as a function of distance from the source
Frequency-Domain Concepts
Fundamental frequency - when all frequency components of a signal are integer multiples of one frequency, it’s referred to as the fundamental frequency
Spectrum - range of frequencies that a signal contains
Absolute bandwidth - width of the spectrum of a signal
Effective bandwidth (or just bandwidth) - narrow band of frequencies that most of the signal’s energy is contained in
Frequency-Domain Concepts
Any electromagnetic signal can be shown to consist of a collection of periodic analog signals (sine waves) at different amplitudes, frequencies, and phases
The period of the total signal is equal to the period of the fundamenta
CYWUSB6935: WirelessUSB LR 2.4-GHz DSSS Radio SoCPremier Farnell
The document introduces the WirelessUSB technology and the CYWUSB693 WirelessUSB transceiver chip. It provides an overview of WirelessUSB and how it compares to other wireless technologies like Bluetooth and Zigbee. It then describes the key features of the CYWUSB6935 chip such as its 2.4GHz radio, data throughput, and integrated components. Finally, it outlines some potential applications for WirelessUSB technology and provides a functional description and block diagram of the CYWUSB6935 chip.
Modems convert digital data to analog signals and vice versa, allowing digital devices like computers to communicate over analog networks. Remote access servers (RAS) terminate connections from remote users and prepare data for transmission over packet networks, enabling services like remote access, VoIP, and virtual private networks. However, current RAS equipment has limitations in channel density, power consumption, and processing capability that will reduce their usefulness for newer applications.
The document discusses various networking concepts including:
- Common network topologies like bus, star, ring, and mesh and the characteristics of each.
- Twisted pair cabling types like UTP, STP, and fiber optic.
- Network devices like hubs, switches, routers, and the differences between LANs, WANs, intranets, and the internet.
- The OSI model which defines 7 layers of networking with specific functions at each layer to prepare data for transmission.
This document provides an overview of various networking devices used for interconnecting local area networks (LANs). It describes the functions of repeaters, hubs, bridges, routers, gateways, and switches. Repeaters operate at the physical layer to amplify and extend signals. Hubs operate at the physical layer, copying and broadcasting packets to all ports. Bridges operate at the data link layer and learn MAC addresses to forward packets between connected segments. Routers operate at the network layer, using network addresses and routing tables to path packets between different networks. Gateways can translate between incompatible networks, operating across multiple OSI layers. Switches provide bridging functionality with greater efficiency than hubs.
This document provides an overview of LAN network design and various high-speed networking technologies. It discusses the evolution of networking needs that led to faster LANs, describes Ethernet and some of its variants like Fast Ethernet and Gigabit Ethernet. It also covers wireless LAN technologies and fiber optic networks like Fibre Channel. Key concepts explained include CSMA/CD, full duplex operation, and different physical layer specifications for networks operating at speeds of 100Mbps, 1Gbps, and 10Gbps.
Network architecture is the design of a communications network, including its physical components, functional organization, configuration, operational principles, procedures, and data formats. The most prominent network architecture today is the Internet Protocol Suite framework underlying the Internet. Network architecture specifications can also describe the products, services, rates, and billing structures of a communications network. In distributed computing, network architecture is sometimes used synonymously with the structure and classification of distributed application architecture, as distributed application nodes are often referred to as a network.
The document provides an overview of key concepts in mobile computing including wireless telephony systems like GSM and CDMA. It discusses issues in mobile computing like interference and time-varying channels. It also covers wireless access technologies, multiple access techniques for sharing wireless spectrum like FDMA, TDMA, CDMA and the cellular concept for enabling frequency reuse in wireless networks.
Transmission media are located below the physical layer and are used to transmit signals representing data. There are two main types of transmission media: guided media (wired), which provide a conduit for transmission, and unguided media (wireless), which transmit via electromagnetic waves without a physical pathway. Common guided media include twisted-pair cable, coaxial cable, and fiber-optic cable. Unguided media include radio waves, microwaves, and infrared. Each type of transmission media has different characteristics that determine its suitable uses.
The document discusses various types of transmission media, including guided media like twisted pair, coaxial cable, and optical fiber, as well as wireless transmission using frequencies, antennas, and propagation modes. It provides details on the characteristics, applications, benefits, and limitations of each medium. Key points are that twisted pair is commonly used for short-distance communication, while coaxial cable and optical fiber can support higher data rates over longer distances and in different applications. Wireless transmission employs frequencies and antennas to transmit through air or space.
This document summarizes different types of transmission media used for data and computer communications. It discusses guided media like twisted pair, coaxial cable, and optical fiber as well as unguided wireless transmission. It describes the characteristics, bandwidth, attenuation, and limitations of each medium. Key factors that determine the quality of transmission through different media include bandwidth, transmission impairments, interference, and the number of receivers in guided media.
This document discusses various methods for compressing analog and digital data. It begins by explaining why analog signals are modulated, such as to allow for more efficient transmission. It then covers analog to digital conversion techniques like pulse code modulation (PCM). On the digital side, it discusses lossless compression methods like run-length encoding, Huffman encoding, and Lempel-Ziv encoding. Lossy compression techniques like JPEG and MPEG are also summarized. The document aims to provide an overview of different data compression strategies.
This document discusses different types of transmission media used to transmit signals and data in communication networks. It describes guided media such as twisted pair cable, coaxial cable, and fiber optic cable, which provide a physical path for signal propagation. It also covers unguided or wireless media that transmit signals through air using radio waves, microwaves, or infrared. The key characteristics, applications, and performance of each transmission medium are outlined.
Chapter 4-Transmission Media - guided and unguided .pptxssuser32eccd
transmission medium is the physical path between transmitter and receiver
guided media – guided along a solid medium
unguided media – atmosphere, space, water
characteristics and quality determined by medium and signal
guided media - medium is more important
unguided media - bandwidth produced by the antenna is more important
key concerns are data rate and distance
The document discusses various topics related to physical layer communication including:
1. Bandwidth-limited signals and the relationship between data rate and harmonics.
2. Different transmission media such as magnetic media, twisted pair, coaxial cable, and fiber optics. It describes their properties and applications.
3. Wireless transmission using different parts of the electromagnetic spectrum such as radio waves, microwaves, and infrared. It also discusses communication satellites.
Orthogonal frequency-division multiplexing (OFDM)
[1] is a method of encoding digital data on multiple carrier
frequencies. OFDM[1] has developed into a popular scheme
for wideband digital communication, whether wireless or
over copper wires, used in applications such as digital television
and audio broadcasting, DSL Internet access, wireless networks,
powerline networks, and 4G mobile communications. In the
Several wireless standards such as IEEE 802.11a[2] and
HiperLAN2[3].The orthogonality of the subcarriers is no longer
maintained which results in ICI (Inter carrier Interference)[4]
.ICI reduction techniques achieve a better SNR and BER in
OFDM at zero phase noise variance . This technique will use a
large number of closely spaced orthogonal subcarriers to avoid
phase noise. It provides high data rates with sufficient robustness
to radio channel damages. A major problem in OFDM is carrier
frequency offset error between the transmitted and received
signals. Due to this the orthogonality of the subcarriers is no
longer maintained which results in ICI (Inter carrier
Interference). In this paper, we used the ICI self-cancellation
technique and reduced the ICI and improved the BER and SNR
we are also calculate the SNR=15db and 20db at different phase
noise variance.
SONET/SDH are digital fiber optic transmission standards developed independently in the US and Europe to transmit data at high speeds over fiber optic cables. SONET defines a hierarchy of electrical signaling levels called STS and uses synchronous TDM multiplexing. It can transmit data from 155 Mbps to 2.5 Gbps and supports ring topologies. SONET defines layers for signal transmission including path, line, section and physical layers. SDH is the international version of SONET and uses similar framing and network elements like multiplexers, regenerators and cross-connects to transmit digital signals over fiber optic networks. DWDM further increases fiber capacity by transmitting multiple wavelengths/channels over the same fiber using wavelength division
This document provides an overview of Orthogonal Frequency Division Multiplexing (OFDM). It defines OFDM as a digital modulation technique that splits a high-rate data stream into multiple lower-rate streams and transmits them simultaneously over a number of subcarriers. The main advantages of OFDM are high spectral efficiency, resilience to radio interference and multipath fading. Common applications of OFDM include wireless networks, Wi-Fi, WiMAX and digital audio/video broadcasting.
The document discusses various methods for accessing satellites including frequency division multiplexing (FDM), time division multiplexing (TDM), and code division multiple access (CDMA). It also covers satellite microwave transmission which uses communication satellites as microwave relay stations in space to link ground-based transmitters and receivers over long distances.
Communication involves a sender encoding a message and sending it through a medium to a receiver. It requires a sender, receiver, message, and medium. Common mediums include twisted pair cable, coaxial cable, fiber optics, radio waves, infrared, microwaves, and satellites. Twisted pair is commonly used for analog and digital transmission over short distances. Coaxial cable and fiber optics can transmit over longer distances due to better shielding and bandwidth. Wireless technologies like radio, infrared, and microwaves are used for line-of-sight transmission without cables. Satellites are used when direct transmission is not possible due to obstacles like the curvature of the Earth.
The document discusses various types of transmission media used for data communication, including guided media like twisted pair, coaxial cable, and optical fiber, as well as unguided wireless transmission. It covers characteristics of each medium such as bandwidth, attenuation, interference susceptibility, and data rates. Key concerns in transmission media design are maximizing bandwidth to increase data rates while minimizing transmission impairments over distance.
OFDM is a digital multi-carrier modulation technique that encodes data over multiple carrier frequencies. It splits a high-rate data stream into multiple lower-rate streams that are transmitted simultaneously over separate subcarriers. The subcarriers are chosen so they are orthogonal to each other, allowing them to be packed closely together without interference. OFDM provides high spectral efficiency, resilience to radio interference and multipath distortion, and works well for broadband applications including wireless networks, digital television and audio broadcasting.
This document summarizes different transmission media used for communication including guided media like twisted pair, coaxial cable, and optical fiber as well as unguided wireless transmission. It discusses characteristics of each medium such as bandwidth, attenuation, delay, and repeater spacing. Key concerns for any transmission include data rate, distance, and impairments from attenuation and interference. The document also provides tables comparing specifications of different cable categories and wavelength bands for optical fiber.
This document summarizes various transmission media used for data and computer communications. It discusses both guided media like twisted pair, coaxial cable, and optical fiber as well as unguided or wireless media. Key factors in transmission include bandwidth, data rate, attenuation, interference, and the number of potential receivers. Different media have varying characteristics like maximum bandwidth, typical attenuation rates, and optimal repeater spacing. The document also examines wireless transmission frequencies, antenna types, wireless propagation techniques, and challenges like free space loss, multipath interference, and atmospheric absorption that affect wireless signals.
Analog-to-digital conversion (ADC) is an electronic process in which a continuously variable, or analog, the signal is changed into a multilevel digital signal without altering its essential content.
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1. Data two types
Analog
Form of sinusoidal wave pattern…
changing states
Digital
Form of ON/OFF pattern… pulses
2. Communication
Analog data transmission
States changes (follows SIN wave)
Maintenance cost is low
But.. Cost of transmission is high
Effect of environment is very high
Amplifier circuit loses data
3. Digital data transmission
Follow ON/OFF pattern
Mainainance cost is high
Transmission cost is low
Environment factor… low
No loss while using amplifier/reapeter
4. Channel Characteristic
Ideal channel
Should convey the maximum from
sender to receiver
Should not ALTER…(additional noise)
No distance restriction
Convey cost should be maintain
Type
Analog
digital
5. Close look to the digital channel
Channel carries BITS
Measurement… how many BIT/ second
called bit rate (bps)
The bps is the rate at which the channel
can carry BITS (digital data)
Distribution of bits determine bit rate
shorter the duration greater bps
6. TRANSMISSION MODES
Simplex
DATA
Sender receiver
Only one way communication …
unidirectional flow
Interactive part is absent… so no ackw
Examples… keyboard/printer.. Radio, TV
Cheapest… but low efficient
7. Half duplex
Sender/ DATA Receiver
Receiver Sender
Both communication thru same
medium
Only one is active at a time … no one at
the same time
Either send or receive at a time
Examples HDD, RAM
8. Full Duplex
Data
Sender Receiver
Receiver Sender
Simultaneous transmission in both
direction
Full interactive communication
Examples… telephone/mobile
costly
9. Asynchronous Mode Transmission
Referred as ON/OFF (Start/stop)
transmission
Transmission takes place character by
character
Character sequence
Irregular time interval
10. Each channel is started by ‘start’ bit
and ended by ‘stop’ bit
Channel remain unused between
the two character… hence at each
character start and stop bit is
required to notify the receiver
Summery :- Data is transmitted
character by character at irregular
time interval
11. Synchronous Mode Transmission
Character are grouped as a block
Series of such blocks are
transmitted
Each block is started by HEADER
and ended with TRAILER
information and each block may
contain hundreds of characters
Indefinite time interval between blocks
12. Summary
Synch
Entire blocks of characters are framed and
transmitted
Expensive
Efficient
Need for BUFFER and accurate synch and
is required.
13. Asynchronous
Data is transmitted character by
character.
Less costly… but not efficient
No buffer is required… but channel will
remain unused
14. Type’s Of Media
Guided media
Signals are guided thru solid media
(like copper wire)
Thru cables
Unguided media
Signals are not guided… not thru solid
medium (use of air)
Usage of radio waves
15. Guided Media
Twisted pair cable
Two insulated wires (1mm thickness)
With each other
Less expensive
FD transmission
Can be used for analog and digital
Flow efficient is carries the signal
depends on thickness and distance
Very efficient for short distance (less
then 100meters)
16. More noise friendly
Normally Used in LAN
If more twisted per centimeter… results
less noise effect and better will be the
quality
Easy to maintain
If used less then 100 meters can give
up to 9600bps
17. CO-AXIAL CABLE
Better shielding … higher data bps
@longer distances …several tens of bps
at distances up to thousands feet
Used for analog (75 ohm cable) and
digital (50 ohm cable) communication
Costlier then twisted pair
Wire mesh conductor
Protective
Copper wire plastic
covering
Insulating material
18. OPTICAL FIBER
Inner core… glass/plastic… conducts
the light…size is in microns(1/25000
inch)
Cladding … reflects the light
Most expensive
Data rate up to 100 mbps to 2Gbps
No effect of EM noise
Mainly for digital
Half duplex (FD cause interference)
19. cladding
Fiber corer
jacket
Electrical signal Light signal To
To Electrical signal
Light converter Converter
Fiber optic
20. UNGUIDED MEDIA
Radio wave can travel ideally with
the speed of light (in vacuum) –
cover long distance
RF are omni directional
RF is subjected to interference at
any frequency
Visible
Micro
light
Radio wave infrared UV X Ray
4 5 6 7 8 9 10 11 16
Hz
21. TERRESTRIAL MICROWAVE TRAN.
4 TO 6 GHz and 21 to 23 GHz
Cheaper then fiber optic
1 to 4 mbps travel in straight line
(hence line of sight is required)
Cost depend on distance
Long distance telephone, cellular, TV,
link to cities etc..
22. SATELLITE MICROWAVE TRANS.
One antenna is on a satellite
4 -6 GHz and 11-14GHz
Use of satellite- cost
Normally uplink is 6 KHz and downlink
is 4 KHz
Earth based station required careful
adjustment
Can reach most remotes places on
earth
23. INFRAERED
Used for short distance communication
Do not pass thru solid object
Generally cheaper
Used for wireless LAN, remote controls
etc..
licensing is not required.
24. MODEMS
Types
A) Landline :- connected to PSTN…
having jacks RJ11
Internal – inside computer
External –separate device… outside the
computer… connected to serial port
PCMCIA – small size normally used for
laptops.
Personal computer memory card
(designed by) international associatioan.
25. B) Wireless
Radio transmitters/receiver generally used
for mobile device.
RJ11 is not there instead they can access
thru radio waves.
If it is out of range – no use.
C) LAN
Allow shared remote access to LAN.
26. Standards
Bell Modem :- designed by bell lab. There
are 103/113 series,202 series, 212 series,
201 series, and 208/9 series.
ITU- T modem- V.22,V.26,V.29
V.26 from 1200-2400 bps… user phase shift
keying.
V.22 bit- 600 baud line… during each signal
period (baud) the modem conveys 4 data bit
600*4= 2400 bps.
V.29 operating at 2400 baud *4 =9600 bps.
27. Encoding Techniques
Analog data to Analog signal
Digital data to Digital signal
Digital data to Analog signal
Analog data to Digital signal
28. Analog data to Analog signal
Types of modulation
1) Amplitude
Carrier
30. Modulation
To modulate to mix the signal with the carrier.
Process of encoding signals (information) for the
transmission
Translate the source signal, base band to a
band pass signal (high frequency compared to
the source frequency).
Source signal – MODULATING signal.
Band pass signal – MODULATED signal.
MODULATION is done by varying the amplitude
or frequency of high frequency carrier according
to the modulating signal.
31. Amplitude Modulation
Amplitude of high frequency carrier signal
is varied accordance to the instantaneous
amplitude of the modulating signal.
Easy
Environment friendly.
Strength decrease with distance.
32. Frequency Modulation
FM signal constant MODULATED but
frequency VARIES IN ACCORDING TO
THE SIGNAL to be transmitted.
Mixing of two frequency high frequency
(carrier) with the signal (low
frequency) compound frequency
varying according to signal.
Least affected by noise.
Requires high bandwidth than AM.
34. Phase Modulation
The shape of the carrier signal (phase) is
made to change at given pint of time.
The difference between two sine signals is a
phase angle… normally 180 out of phase.
USES:- medium speed modems use phase
modulation to convert digital signals into
phase modulated signals. This process of
phase shifting keying (PSK) allows modem to
modulate and demodulate
36. Digital data to Digital signal
Digital data to digital signal
conversion.
Equipment less complex and
expensive then digital data to
analog modulation equipment.
One logic state represented by
positive the other by negative
voltage
Data rate
Rate of data transmission in bps.
37. Schemes of D to D
1)Non return to zero –level (NRZ-L)
To different voltage for 0 & 1 bits
Voltage constant during bit interval
No transmission i.e. return to 0 voltage
E.g. absence of voltage for 0, constant
positive for 1
More often negative voltage for 1 value
and positive for the other
39. 2) non return to 0 interval
Constant voltage pulse for duration of
bit
Data encoded else presence or absence
of signal transmission at beginning of
bit time
Transition (low to high or high to low)
denotes binary 1
No transition denotes binary 0
43. 4)Defrential Manchester
Mid bit transition is clocking only
Transition at start of a bit period
represent 0
No transition at start of a bit period
represent 1
45. Digital Data to Analog Signal
Public telephone system
300 Hz to 3400 Hz.
Amplitude Shift Keying (ASK).
Frequency Shift Keying (FSK).
Phase Shift Keying (PSK).
46. ASK (Amplitude Shift Keying)
Values represented different amplitude
of carries.
Usually one amplitude as 0.
i.e. presence or absence of carrier is
used.
Susceptible to sudden gain changes.
Inefficient.
Up to 1200 bps on voice grade line.
Used over optical fiber.
48. Binary Frequency Shift Keying
Most common form is Binary FSK.
Two binary values represented by 2
different frequencies (near carrier).
Less susceptible to error than ASK.
Up to 1200 bps on voice grade lines.
High frequency radio .
Even higher frequency on LANs using
co-ax.
50. Binary phase shift keying (BPSK)
Phase of carrier signal is shifted to
represent data.
Binary PSK
Two phases represent two binary digits.
Differential PSK
Phase shifted relative to previous
transmission rather than some reference
signal.
52. Analog Data To Digital Signal
Digitization
Conversion of analog data in to digital
data.
Digital data can then be transmitted
using NRZ-L.
Digital data can then be converted to
analog signal.
Analog to digital conversion done using a
codec.
Pulse code modulation conversion of
analog data in to digital data.
53. Digitizer Modulator
Analog data
Digital Data
(voice)
54. Pulse code modulation
It’s a digitizing process in which analog
is represented in digital form.
The sound are transformed in to pulse
by codec…sampling of the amplitude of
the analog signals at very short interval
of time… the sampled valued converted
in to digital number of 0’s and 1’s… and
finally it is transmitted.
55. At the receiving, the original A/D is
reversed… voltage values are converted
read and production of the exact signal
will be achieved.
If a signal is sampled at regular interval at
a rate higher than twice the highest signal
frequency, the samples contain all the
information of the original signal.
Voice data limited to below 4000Hz.
Required 8000 samples per second.
Each sample assigned digital value.
56. CODEC (Compressor/DECompressor)
Its an electronic circuit that convert analog
to digital.
Converts human voice in to digital code
using pulse code modulation.
The resulting digital signal can travel
through all digital communication
equipment… provides more reliable and less
costly compared to analog.
Its also converting back to voice.
CODEC electronics used in digital phone.
57. Multiplexing
Multiplexing is a set of techniques that
allows the simultaneous transmission
of multiple signal across a single data
link.
Whenever the transmission capacity of
a medium linking two devices is
greater then the transmission needs of
the devices, the link can be shared in
order to maintained the utilization of
the link, much at one cable can carry
a hundreds of TV channel.
59. Frequency division mux (FDM)
In FDM signal generated by each sending
device modulated different carrier
frequencies. These modulated signals are
then combined in to a single composite signal
that can be transported by the link. The
carrier frequencies have to be different
enough to accommodate the modulation and
demodulation signals.
(refer fig.) The first PC terminal is sending
“1010” where as second terminal is sending
“0110”. The multiplexing process starts by
applying amplitude modulation in to each
signal by using different carrier frequencies
as f1 and f2
60. FDM mux process
Amplitude
Modulation
101 0
With
Carrier f1
Modulated
signal +
Amplitude
0 11 0 Modulation
With
Carrier f2
Signal connected
61. In demux process, we use filters to
decompose. The multiple signal in
to its constitute signals. Then each
signal is passed to a amplitude
demodulation process to separate
the carrier signal from the message
signal. Then the message signal is
sent to the waiting receiver.
62. Signal with
Carrier f1
Bandwidth f1
Amplitude 101 0
Filter
Filter
Amplitude 0 11 0
Bandwidth f2
Signal with
Carrier f2
63. Time Division mux (TDM)
In the TDM multiple transmission can
occupy a single link by subdividing
them and interleaving the portion. We
say that TDM is a round robin use of a
frequency.
64. Synch TDM
The mux allocate exactly the same time
slot each device at all times, whether or
not a device has any thing to transmit.
Time slot 1 ,for example is assigned to
device 1 alone and can not be used by
any other device.
FRAME: In synch TDM, a frame consist of
one complete cycle of time slots. Thus the
number of slots in frame is equal to the
number of inputs.
66. Synch TDM: mux process
1AAAA
2 BB
A D A D BA DCBA
MUX
3 C
4 DDD
67. Synch TDM: demux process
AAAA
D
BB
A D A D BA DCBA E
M
U
X C
DDD
68. Asynch TDM
In asynch TDM each slot in a frame is not
dedicated to the fix device. Each slot
contain an index of the device to be sent
to and a message. Thus the number of
slots in a frame is not necessary to be
equal to the number of inputs devices.
More than one slots in a frame can be
allocated for an input device. Asynch TDM
allows maximization the link. It allows a
number of lower speed input lines to be
multiplexed to a single higher speed line.
69. Synch TDM: mux process
1AAAA
BB
A D A D BA DCBA
MUX
C
DDD
70.
71. FRAME: In asynch TDM, a frame contain a
fix number of time slots. Each slot has an
index of which device to receive.
73. MULTIPLE ACCESS TECHNOLOGIES
FOR
WIRELESS COMMUNICATION
COMMUNICATION : Fixed BAND of
Frequency Spectrum.
Multiple Access Methods - WHY ?
SHARE THE FREQUENCY SPECTRUM.
Differentiates the signals from different
sources , without degrading the Quality.
Different techniques of SHARING …
called Multiple Access Methods /
Techniques / Schemes / Technologies.
74. MULTIPLE ACCESS TECHNOLOGIES
FOR
WIRELESS COMMUNICATION
THREE Basic Multiple Access Methods
currently in use :-
FDMA
FREQUENCY DIVISION MULTIPLE ACCESS
TDMA
TIME DIVISION MULTIPLE ACCESS
CDMA
CODE DIVISION MULTIPLE ACCESS
75. FDMA
(Frequency Division Multiple Access)
Channel 2
Channel 3
Channel 5
Channel 4
Channel 1
User B
User E
User A
User D
User C
Frequency
F1 F2 F3 F4 F5
Users SHARE the available spectrum in the
FREQUENCY domain.
Assigns the individual CHANNEL ( Unique
Frequency) to users - Allocated band is called
TRAFFIC CHANNEL. Hence .. Different Users
…..Different Traffic Channels.
76. FDMA
(Frequency Division Multiple Access)
If User A is in USE .. Channel 1 will not be
allotted to others. Disadvantage -> When
Channel is not in Use … can not be used by
others .. Wastage of Resource.
Each Channel has Very LOW Bandwidth ….
Hence Implemented normally in Narrow band
Systems.
Requires TIGHT filtering to reduce the
Channel Interference .
Channel ID = Frequency Slot ID.
77. TDMA
(Time Division Multiple Access)
Time
T3 User C User F User I
T2 User B User E User H
T1 User A User D User G
Frequency
F1 F2 F3
Spectrum is divided in narrow frequency bands
(Like FDMA) and further divided into a number of
time slots.
Each User is allotted a Time Slot that permit access
to the frequency channel for that duration of the
time slot.
78. TDMA
(Time Division Multiple Access)
Traffic Channel ID =
Frequency Slot ID + Time Slot
ID
Periodic train of time slots … make a FRAME.
Each User shares a frequency with several
users.
Transmission for any user is non continuous.
Allocation of different numbers of Time Slots
per frame to users … Better Utilization of
Spectrum…
Analog Systems used FDMA .. Digital Systems
used TDMA.
79. Spread Spectrum Multiple
Access
PN Code - pseudo-noise code …
random binary Sequence / Code.
SSMA - a) Frequency Hopped Multiple
Access (FHMA) & b) Direct Sequence Multiple
Access(DSMA).
FHMA :- Carrier Frequencies of individual user
are VARIED in a pseudo random way.
Based on the PN code of the user .. Each user
occupy the narrow band channel at one
particular time.
Because of the PN … Signals changes channels
rapidly.
Difference between FHMA & FDMA is that the
FHMA signal changes channels at rapid interval.
80. CDMA
(Code Division Multiple Access)
PN codes
Code 3 User C
Code 2 User B
Code 1 User A
Frequency
F1
DSMA is also called CDMA.
Unique PN code is assigned to unique user.
Users share the Block of frequency spectrum on
the basis of PN code.
81. CDMA
(Code Division Multiple Access)
Channel ID = PN Code ID
Utilizes the entire spectrum of allotted spectrum
-
All the PN code modulated signals from the users
are transmitted over the entire spectrum. And
at the receiving end the signals classified as
per the copy of PN sequence .
Unlike FDMA - TDMA … There is no LIMIT of
number of users … but increase in users
degrades the quality.
Each user operate independently with NO
knowledge of other users.
82. CORDLESS TELEPHONE
SYSTEMS
Public
Telephone Fixed Station -
Network ..
(DoT) Base Station
Handset
Cordless Telephone System -
provide the user limited range and
mobility. Coverage rang is few
Tens of Meters to Few hundred
Meters.
83. CELLULAR TELEPHONE
SYSTEMS
The concept was developed in early 70’s by
Bell Laboratories
Extension of your wireless connection to the
public telephone network for any user location
within the range of the system.
The principle of cellular system…To divide a
large geographic area into cells.
Each adjacent Cell Transmitters operate on
different frequencies to avoid interference.
84. CELLULAR TELEPHONE
SYSTEMS
Transmitted power and height of antenna of each
CELL is low so that the same set of frequency can
be used for different cells far apart.
Hence theoretical coverage range and capacity of a
cellular system are therefore UNLIMITED.
Each Cell is represented by HEXAGONE.
85. A cellular System –
An Overview.
Public
Telephone
Network
Mobile
Switching
Center
To Other MSC MSC
Basic Cellular System - Mobile Stations+Base
Stations+Mobile Switching Center.
86. A cellular System -
An Overview.
Mobile Station - Contains a transceiver+
antenna+Control Circuitry
Base Station - Bridge between MS and MSC
MSC - Coordinated the activities of all BS and
connect them to PTN. Plus Billing & System
Maintenance.
The Channel used for VOICE transmission from
BS to MS …called Forward Voice Channel (FVC).
The Channel used for VOICE transmission from
MS to BS …called Reverse Voice Channel (RVC).
87. How it WORKS ?
When MS is turned ON … Searches for the
strongest FVC.
When a Call is made for MS.. MSC dispatches
the request to all BS.
The Mobile Number is broadcasted as a paging
message.
MS acknowledges the Paging message.
BS relays this ACK to MSC .
MSC instructs the BS to select particular
frequency Channel for communication .
88. How it WORKS ?
BS TO RING sends DATA message in FVC TO
RING the MS.
During CALL .. MSC handles the transmitted
power and controls the channel between BS
and MS in order to maintain the Quality ( as MS
is likely in MOBILE mode)
When MS goes out of range of BS … called
HANDOFF …
Two other Channels are also Used besides FVC
& RVC … a) FCC & b) RCC
89. How it WORKS ?
Call from
MSC DoT. Sends
Number to
all BS
Paging
Message for
FCC MS
RCC
BS
FVC
RCC
Receives
FCC Paging
Message
RVC
MS
FVC
RVC
TIME
90. How it WORKS ?
When MS Originates Call… sends all information
to BS.
BS passes information to MSC
MSC Validates .. And If required help from
Public Telephone Network requested.
And the two way PATH will be maintained till
the Call Lasts.
91. Handoff
During the ongoing call if BS senses the LOW
power Quality from MS , it requests
neighboring BS to check the signal level .
( This happens when MS moves to different cell
while in USE)
If the signal is BETTER , current BS signals the
MS to switch over to new BS and inform the
new BS to take over.
This change of SPEECH channel is called
“Handoff”
This changeover will not be noticed /
experienced by the user.
92. Frequency REUSE
E
E F C
F C A
G B
A B D
G
D
BS in adjacent cells are assigned channel
groups … totally different from the neighboring
cells.
BS antennas are designed to cover the
particular cell.
94. 1G Cellular Systems
Based on Analog Cellular Systems
Concept
Depends on Frequency Band , Channel
Spacing and channel coding
Individual calls use different channels
and the Spectrum is shared on the
basis of FDMA
Uses Analog FM for speech
transmission
Normally uses 7 Cell reuse pattern –
provision for Cell splitting.
95. 2G Cellular System
Completely DIGITAL Cellular System
Increased in Capacity ( 3 to 10 times)
MS Terminal Size Reduction
Reduces the Power requirements … Increases
the battery life
Improved Reception
Highly Secured … Interference prone
environment.
Cell Splitting … Better
Wide Area Roaming
More Popular
96. 2G Cellular System
Spectrum Sharing in the digital
environment can be based on ;
TDMA : Each Radio Channel is partitioned in to
number of time slots - each user is assigned a
frequency/time slot COMBINATION
CDMA : A radio Channel is used
SIMULTANEOUSLY by multiple mobile users ,
and the signals from different users are
distinguished by SPREADING them on the
basis of PN code.
97. Global System for Mobile
(GSM)
Introduced in Europe in 1990.
World’s most popular standard now.
A memory device that stores the
subscriber Id , Networks, Countries where
he’s entitled to get services , personal
information is inserted into GSM phones .
(Subscriber Identity Module - SIM).
Example TOI dated 18th March.
Without SIM – non operational.
Encryption is possible … More secured
99. GSM Architecture
MS (Mobile Station)
• Low Power Requirement…0.8-8.0w
• SIM is Required
BSS (Base Station System)
• BSC+BTS (Base Transceiver Station)
• Responsible For Radio Channel Allocation/
Monitoring (BSC)
• Power Control (BSC)
• Handoff Management (BSC) – Reduce The Burden
of MSC
• Digital Signal Processing (BTS)
100. GSM – System Architecture
MSC
Doesn’t contain Info regarding MS .
Call Setup, Supervision & End / Routing
BILLING
MOBILITY Management
Management with Other MSCs , PSTN .
Home Location Register – HLR
Centralized Database of MS falling under MSC
Refer for every Incoming Call
101. GSM – System Architecture
VLR – Visitor Location Register
Temporarily stores the MS … Each roaming MS
visiting MSC.
AUC – Authentication Center
Strongly protected database which handles the
authentication and encryption keys of every MS
Interfaces :
Between BSC & MSC ::: A Interface
Between BSC & BTS ::: Abis Interface
Between BTS & MS ::: GSM Radio Air Interface
SS7 Protocol ::: Signal Correction control part
102. GSM Specifications
RC :: 890 – 915 MHz
FC :: 935 – 960 MHz
Separation ::: 45 MHz
Channel Spacing ::: 200 kHz
Each Channel is TIME SHARED
between 8 subscribers using TDMA
Total number of channel :::
125 (25MHz bandwidth) * 08 = 1000
approximately
104. GSM Traffic Channels
Traffic Channels (TCHs)
Carry digitally encoded user SPEECH or DATA
Control Channels (CCHs)
Carry signaling and synchronizing commands
between BS & MS
Full Rate :
User Speech / Data … one TS per Frame
Half Rate :
Same time slot but sent in alternate frames
Two half rate channel users would share the
same time slot but would alternately transmit
during every other frame
105. TCHs - Types
Full Rate TCH
TCH/FS … Full rate speech channel carries
@13kbps
TCH/F9.6 … Full rate DATA channel @9600bps
TCH/F4.8 … Full rate DATA channel @4800bps
TCH/F2.4 … Full rate DATA channel @2400bps
Half Rate TCH
TCH/HS … half rate of the full rate channel …
6.5kbps
TCH/H4.8 …half rate DATA @4800bps
TCH/H2.4 …half rate DATA @2400bps
106. CCH - Types
Three Main Control Channels – Broadcast
Channel (BCH), Common Control Channel
(CCCH) & DEDICATED Control Channel
(DCCH)
BCH – Operates only on Forward link …
Synchronization for all MS
Broadcast Control Channel – BCCH … used to
broadcast info. Such as cell & network identity
. Plus … Channel structure , channel
availability and congestion parameters.
Frequency Correction Channel – FCCH …
allows each MS to synchronize its internal
frequency as of BS
Synchronization Channel – SCH … used to
identify the serving BTS
107. CCH - Types
Common Control Channel – CCCH – used
to page specific MS , assign signaling
signals to specific MS and receive
requests for service from MS
Paging Channel – PCH … provides paging
signals from BSC to all MS in the cell … used
to provide cell broadcast ASCII text messages
to all MS – SMS feature.
Random Access Channel – RACH … reverse
link used by MS .. Used by MS to originate
calls
Access Grant Channel – AGCH … used by the
BSC to provide forward link communication
to the MS and carries signals which instructs
108. CCH - Types
Dedicated Control Channels (DCCH) – bi-
directional in nature like traffic channels …
Stand-alone Dedicated Control Channel –
SDCCH …ensures that MS will remain
connected with BSC while MSC verify the MS …
Slow Associated Control Channel – SACCH …
carries general info. Between the BTS and MS…
on the forward , regular signals to MS like
transmitted power … in reverse , it carries
received signal strength , quality of TCH info.
Fast Associated Control Channel – FACCH …
carries urgent messages same as of SDCCH …
urgent message like handoff request .