This document provides an overview of wireless networks and communication systems. It discusses digital and analog communications, examples of wireless systems, and the differences between wireless and wired networks. It also covers wireless system architecture, multiple access techniques, the evolution of cellular networks from 1G to 4G, and various wireless technologies like WLANs, Bluetooth, ad hoc networks, and more. Key concepts around cellular concepts and the components of communication systems are also summarized.
This document provides an introduction to wireless communications and networks. It outlines topics that will be covered, including an overview of communication systems, digital vs analog communications, examples of wireless systems, challenges of wireless communications, wireless system architecture, multiple access techniques, evolution of cellular networks from 1G to 3G, and wireless local area networks. It then goes on to describe the components of a communication system, digital and analog signals, noise immunity of digital signals, and the interface between analog and digital systems using A/D and D/A conversion.
A brief discussion of Introduction to communication systems.
Prof. H.Amindavar complementary notes for the first session of "Advanced communications theory" course, Spring 2021
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.
Lecture 1 introduction to communication systemsavocado1111
This document provides an introduction to communication systems. It defines communication as the exchange of information from a source to a destination. An electronic communication system is defined as the whole mechanism of sending, receiving, and processing information electronically from source to destination. The main objectives of a communication system are to produce an accurate replica of the transmitted information and to transfer information between two or more points with minimum error. The basic elements of a communication system are an information source, transmitter, channel, receiver, and destination. Modulation is the process of modifying a carrier wave systematically by a modulating signal to make it suitable for transmission through a channel. There are two main types of modulation: analog modulation and digital modulation.
Analysis of Simulation Parameters of Pulse Shaping FIR Filter for WCDMAijsrd.com
The application of signal processing techniques to wireless communications is an emerging area that has recently achieved dramatic improvement in results and holds the potential for even greater results in the future as an increasing number of researchers from the signal process and communications areas participate in this expanding field. From an industrial viewpoint also, the advanced signal processing technology cannot only dramatically increase the wireless system capacity but can also improve the communication quality including the reduction of all types of interference. The present paper deals with simulation model of square root raised cosine pulse shaping filter for WCDMA with different parameters of the filter at 5Mhz.The present paper deals with study of Simulation Parameters (Number of Bits, Number of Errors) of Pulse Shaping FIR Filter at different value of group delay(2,4,6,8) to the calculate BER for WCDMA.
The document describes the key components of basic cellular systems including circuit-switched and packet-switched systems. It discusses two types of circuit-switched systems: analog and digital. The main components of an analog system are mobile units, cell sites, and a mobile telephone switching office. A digital system consists of mobile stations, base transceiver stations, base station controllers, and switching subsystems. It also outlines the main elements of a packet-switched cellular network and discusses performance criteria such as voice quality, data quality, coverage, and special features.
The document provides an overview of the evolution of wireless telecommunication systems and networks from 1G to 4G. It discusses the key aspects of 1G cellular networks including AMPS (Advanced Mobile Phone System), the first commercial cellular network deployed in the United States. It describes the components and operations of AMPS including frequency bands, channel structure, call setup procedures for mobile originated and terminated calls, and signaling between the mobile station, base station, and mobile switching center. The document also briefly introduces 2G, 3G and 4G networks as later generations of cellular standards.
This document provides an introduction to wireless communications and networks. It outlines topics that will be covered, including an overview of communication systems, digital vs analog communications, examples of wireless systems, challenges of wireless communications, wireless system architecture, multiple access techniques, evolution of cellular networks from 1G to 3G, and wireless local area networks. It then goes on to describe the components of a communication system, digital and analog signals, noise immunity of digital signals, and the interface between analog and digital systems using A/D and D/A conversion.
A brief discussion of Introduction to communication systems.
Prof. H.Amindavar complementary notes for the first session of "Advanced communications theory" course, Spring 2021
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.
Lecture 1 introduction to communication systemsavocado1111
This document provides an introduction to communication systems. It defines communication as the exchange of information from a source to a destination. An electronic communication system is defined as the whole mechanism of sending, receiving, and processing information electronically from source to destination. The main objectives of a communication system are to produce an accurate replica of the transmitted information and to transfer information between two or more points with minimum error. The basic elements of a communication system are an information source, transmitter, channel, receiver, and destination. Modulation is the process of modifying a carrier wave systematically by a modulating signal to make it suitable for transmission through a channel. There are two main types of modulation: analog modulation and digital modulation.
Analysis of Simulation Parameters of Pulse Shaping FIR Filter for WCDMAijsrd.com
The application of signal processing techniques to wireless communications is an emerging area that has recently achieved dramatic improvement in results and holds the potential for even greater results in the future as an increasing number of researchers from the signal process and communications areas participate in this expanding field. From an industrial viewpoint also, the advanced signal processing technology cannot only dramatically increase the wireless system capacity but can also improve the communication quality including the reduction of all types of interference. The present paper deals with simulation model of square root raised cosine pulse shaping filter for WCDMA with different parameters of the filter at 5Mhz.The present paper deals with study of Simulation Parameters (Number of Bits, Number of Errors) of Pulse Shaping FIR Filter at different value of group delay(2,4,6,8) to the calculate BER for WCDMA.
The document describes the key components of basic cellular systems including circuit-switched and packet-switched systems. It discusses two types of circuit-switched systems: analog and digital. The main components of an analog system are mobile units, cell sites, and a mobile telephone switching office. A digital system consists of mobile stations, base transceiver stations, base station controllers, and switching subsystems. It also outlines the main elements of a packet-switched cellular network and discusses performance criteria such as voice quality, data quality, coverage, and special features.
The document provides an overview of the evolution of wireless telecommunication systems and networks from 1G to 4G. It discusses the key aspects of 1G cellular networks including AMPS (Advanced Mobile Phone System), the first commercial cellular network deployed in the United States. It describes the components and operations of AMPS including frequency bands, channel structure, call setup procedures for mobile originated and terminated calls, and signaling between the mobile station, base station, and mobile switching center. The document also briefly introduces 2G, 3G and 4G networks as later generations of cellular standards.
This document discusses analog and digital modulation techniques used in communication systems. It defines key concepts like signals, bandwidth, transmitters, receivers and communication channels. It then explains different types of analog modulation like amplitude modulation, frequency modulation and phase modulation. Next, it covers digital modulation techniques and their advantages over analog techniques like higher noise immunity. The document lists various digital modulation schemes including amplitude shift keying, frequency shift keying, phase shift keying etc and provides a brief overview of each. In less than 3 sentences.
Principles Of Electronic Communication SystemSagar Kumar
This document is an excerpt from Chapter 1 of the textbook "Principles of Electronic Communication Systems" by Louis E. Frenzel, Jr. It provides an overview of key topics in electronic communication systems that are covered in Chapter 1, including the significance of human communication, basic components of communication systems, types of electronic communication (analog vs. digital, simplex vs. duplex), modulation and multiplexing techniques, the electromagnetic spectrum, and bandwidth. The document discusses these topics in detail through text and illustrations.
Cellular communication systems have evolved through multiple generations from analog 1G to digital 4G systems. A cellular network is divided into geographical areas called cells served by base transceiver stations. Cells are grouped into clusters where frequencies are reused to allow for more subscribers. When making a call, the cellular phone registers with the local base station which routes the call through switching centers to establish communication with the intended recipient. Modern cellular networks support additional services beyond voice like texting, internet access, and location tracking through technologies like GSM that employ protocols like TDMA for efficient frequency usage.
The document discusses several topics related to digital signal processing and telecommunications networks:
1) It explains why analog signals need to be converted to digital for processing by microprocessors, and describes the steps of analog to digital and digital to analog conversion.
2) It defines pulse code modulation (PCM) and its role in encoding analog signals like speech into digital signals for transmission.
3) It discusses the use of multiplexing to combine multiple signals into a single channel for transmission over networks in order to save costs.
4) It provides an overview of the OSI model and its layered approach to network communication.
introdution to analog and digital communicationSugeng Widodo
This document provides a historical overview of developments in analog and digital communications. It discusses technologies like the telegraph, radio, telephone, electronics, television, digital communications, computer networks, satellite communications, and optical communications. It also describes applications of communications technologies like broadcasting and point-to-point links. Finally, it outlines primary resources for communication systems including transmitted power and channel bandwidth.
1 . introduction to communication systemabhijitjnec
This document provides an introduction to communication systems. It discusses the basic components and elements of a communication system including the input, transmitter, channel, receiver and output. It also covers various modulation techniques used to transmit signals over different types of channels. Finally, it discusses different types of signal propagation including ground waves, sky waves and space waves and how radio frequency spectrum is allocated internationally.
Telecommunication involves the transmission of information over distances using communication systems. A communication system has three main parts: a transmitter that processes the input signal, a transmission channel as the medium, and a receiver that operates on the output signal. Messages can be analog, varying continuously over time like voice, or digital, consisting of discrete symbols. Transducers convert between message forms. Communication channels can be simplex, half-duplex, or full-duplex depending on transmission direction. Undesirable effects like noise, distortion, interference and attenuation affect signal quality during transmission. Modulation encodes information onto carrier waves to transmit signals over long distances.
The document summarizes key concepts from chapters 13-17 of a homework assignment on telecommunications circuits. It includes definitions of terms like VSAT (very small aperture terminal), PON (passive optical network), and discusses topics like the differences between single mode and multimode fiber, components of the access network like POTS lines, and signal transmission parameters used in circuit design like bandwidth and loss.
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.
The document provides an overview of topics covered in Chapter 1 of an introduction to electronic communication textbook. It discusses the significance of human communication, components of communication systems including transmitters, channels, and receivers. It also describes types of electronic communication such as simplex, full duplex, and digital/analog signals. Modulation, multiplexing, and the electromagnetic spectrum are explained. The chapter concludes with an overview of various communication applications and careers in the communication industry.
This document provides an overview of telecommunication networks and their evolution. It discusses the main components of basic telecommunication networks including telephone exchanges, distribution points, and switching rooms. The document also covers digital switching techniques, multiplexing methods like FDM and TDM, signaling systems, concepts of PCM, broadband applications, and optical fiber cables.
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
This document discusses the evolution of cellular communication networks from early radio technologies to modern 4G networks. It covers key developments like the invention of the transistor, the first commercial cellular network, and the progression of cellular generations from 1G analog to 4G digital networks. It also provides details on cellular network components, frequency reuse, call setup processes, and the GSM standard including features like SIM cards, IMEI, IMSI, and TMSI identifiers.
Ch 03 quality of service and telecommunication impairments.sakariachromabook
1) Transmission impairments like attenuation, delay distortion, and noise can degrade signals during telecommunication and cause bit errors. Attenuation weakens signals over long distances, while delay distortion causes phase shifts between frequency components. Thermal noise, intermodulation, crosstalk, and impulse noise all contribute unwanted signals that interfere with the received signal.
2) The maximum rate of error-free data transmission over a channel is called its channel capacity. It depends on the bandwidth, error rate tolerance, and transmission conditions. Network operators face challenges optimizing capacity utilization and traffic management to deliver quality of service within these constraints.
This document summarizes key information from chapters 8-10 of a homework assignment:
- It defines common digital signal rates like DS0, DS1, DS3, and OC-1 according to the North American digital hierarchy.
- It explains terms like DS0, DS1, and DS3 and what each is used for in digital signaling.
- It describes T-1 framing formats and where signaling information is carried.
- It explains the purpose of overhead bits in digital signals and how many DS0s are multiplexed into a T-1.
- It compares SONET bit rates like STS-1 to T-1 and T-3, explaining the difference between OC-
The document discusses various topics related to telecommunications including:
- The differences between an ILEC central office switch and a CLEC regional switch site.
- The purpose of a DSX panel and why two ports are required for connections.
- Standard sizes for relay racks and what DACs are used for.
- Key terms related to outside plant design like CSA, feeder cables, and distribution cables.
- Components of the local telephone network like load coils and T-1 repeater housings.
- Equipment used to determine fiber network endpoints like OTDRs.
- Functions of PBX systems and differences from key systems.
- Networking protocols, standards, and technologies discussed
Data Communications,Data Networks,computer communications,multiplexing,spread spectrum,protocol architecture,data link protocols,signal encoding techniques,transmission media,asynchronous transfer mode,routing,cellular networks
Modulation involves adding information to a carrier signal. There are two main types of modulation: analog and digital. Analog modulation varies either the amplitude (AM) or frequency (FM) of a carrier wave, while digital modulation uses techniques like amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK) to transmit digital data. Modems are used to transmit digital data over analog networks like phone lines by modulating and demodulating signals. Common modem types include internal, external, DSL, and cable modems.
Cellular networks divide geographic areas into cells served by low-power base stations to reuse frequencies. Adjacent cells are assigned different frequencies to avoid interference. As capacity demands increase, networks employ techniques like frequency borrowing, cell splitting, cell sectoring, and microcells. Cellular standards like GSM use TDMA to allow multiple users per cell by dividing the air interface into time slots. CDMA spreads user data over a wide bandwidth using unique codes and allows soft handoff between cells. Third generation networks support high-speed data and multimedia services.
A computer network connects devices using communication links. It allows for simultaneous communication and sharing of bandwidth between connected devices sending signals in either direction. There are different types of networks including personal area networks covering a single person, local area networks spanning a building or campus, metropolitan area networks covering multiple cities, and wide area networks spanning countries or continents. Networks rely on protocols that define rules for communication and different hardware technologies for data transmission, including broadcast links that send packets to all machines and point-to-point links that connect individual pairs of machines.
Introduction wireless communication networkRiazul Islam
The document provides an overview of wireless communications and networks. It discusses the history of wireless technologies and how digital communications provide noise immunity over analog signals. It also describes the basic components of a communication system including the transmitter, channel, and receiver. Additionally, it defines key terms related to wireless systems such as mobile station, base station, and handoff. The document outlines some examples of wireless communication systems and highlights challenges in wireless communications compared to wired systems.
This document provides an introduction to wireless communications and networks. It discusses the key components of a communication system including the source, transmitter, channel, receiver and output transducer. It also describes examples of wireless communication systems such as cellular telephone systems, remote controllers and wireless LANs. The document summarizes the characteristics of 1G, 2G and 3G wireless systems and standards. It also discusses wireless local area networks, personal area networks using Bluetooth, and mobile ad-hoc networks. Finally, it outlines the conceptual layers in a wireless network including the physical, data link, network and application layers.
This document discusses analog and digital modulation techniques used in communication systems. It defines key concepts like signals, bandwidth, transmitters, receivers and communication channels. It then explains different types of analog modulation like amplitude modulation, frequency modulation and phase modulation. Next, it covers digital modulation techniques and their advantages over analog techniques like higher noise immunity. The document lists various digital modulation schemes including amplitude shift keying, frequency shift keying, phase shift keying etc and provides a brief overview of each. In less than 3 sentences.
Principles Of Electronic Communication SystemSagar Kumar
This document is an excerpt from Chapter 1 of the textbook "Principles of Electronic Communication Systems" by Louis E. Frenzel, Jr. It provides an overview of key topics in electronic communication systems that are covered in Chapter 1, including the significance of human communication, basic components of communication systems, types of electronic communication (analog vs. digital, simplex vs. duplex), modulation and multiplexing techniques, the electromagnetic spectrum, and bandwidth. The document discusses these topics in detail through text and illustrations.
Cellular communication systems have evolved through multiple generations from analog 1G to digital 4G systems. A cellular network is divided into geographical areas called cells served by base transceiver stations. Cells are grouped into clusters where frequencies are reused to allow for more subscribers. When making a call, the cellular phone registers with the local base station which routes the call through switching centers to establish communication with the intended recipient. Modern cellular networks support additional services beyond voice like texting, internet access, and location tracking through technologies like GSM that employ protocols like TDMA for efficient frequency usage.
The document discusses several topics related to digital signal processing and telecommunications networks:
1) It explains why analog signals need to be converted to digital for processing by microprocessors, and describes the steps of analog to digital and digital to analog conversion.
2) It defines pulse code modulation (PCM) and its role in encoding analog signals like speech into digital signals for transmission.
3) It discusses the use of multiplexing to combine multiple signals into a single channel for transmission over networks in order to save costs.
4) It provides an overview of the OSI model and its layered approach to network communication.
introdution to analog and digital communicationSugeng Widodo
This document provides a historical overview of developments in analog and digital communications. It discusses technologies like the telegraph, radio, telephone, electronics, television, digital communications, computer networks, satellite communications, and optical communications. It also describes applications of communications technologies like broadcasting and point-to-point links. Finally, it outlines primary resources for communication systems including transmitted power and channel bandwidth.
1 . introduction to communication systemabhijitjnec
This document provides an introduction to communication systems. It discusses the basic components and elements of a communication system including the input, transmitter, channel, receiver and output. It also covers various modulation techniques used to transmit signals over different types of channels. Finally, it discusses different types of signal propagation including ground waves, sky waves and space waves and how radio frequency spectrum is allocated internationally.
Telecommunication involves the transmission of information over distances using communication systems. A communication system has three main parts: a transmitter that processes the input signal, a transmission channel as the medium, and a receiver that operates on the output signal. Messages can be analog, varying continuously over time like voice, or digital, consisting of discrete symbols. Transducers convert between message forms. Communication channels can be simplex, half-duplex, or full-duplex depending on transmission direction. Undesirable effects like noise, distortion, interference and attenuation affect signal quality during transmission. Modulation encodes information onto carrier waves to transmit signals over long distances.
The document summarizes key concepts from chapters 13-17 of a homework assignment on telecommunications circuits. It includes definitions of terms like VSAT (very small aperture terminal), PON (passive optical network), and discusses topics like the differences between single mode and multimode fiber, components of the access network like POTS lines, and signal transmission parameters used in circuit design like bandwidth and loss.
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.
The document provides an overview of topics covered in Chapter 1 of an introduction to electronic communication textbook. It discusses the significance of human communication, components of communication systems including transmitters, channels, and receivers. It also describes types of electronic communication such as simplex, full duplex, and digital/analog signals. Modulation, multiplexing, and the electromagnetic spectrum are explained. The chapter concludes with an overview of various communication applications and careers in the communication industry.
This document provides an overview of telecommunication networks and their evolution. It discusses the main components of basic telecommunication networks including telephone exchanges, distribution points, and switching rooms. The document also covers digital switching techniques, multiplexing methods like FDM and TDM, signaling systems, concepts of PCM, broadband applications, and optical fiber cables.
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
This document discusses the evolution of cellular communication networks from early radio technologies to modern 4G networks. It covers key developments like the invention of the transistor, the first commercial cellular network, and the progression of cellular generations from 1G analog to 4G digital networks. It also provides details on cellular network components, frequency reuse, call setup processes, and the GSM standard including features like SIM cards, IMEI, IMSI, and TMSI identifiers.
Ch 03 quality of service and telecommunication impairments.sakariachromabook
1) Transmission impairments like attenuation, delay distortion, and noise can degrade signals during telecommunication and cause bit errors. Attenuation weakens signals over long distances, while delay distortion causes phase shifts between frequency components. Thermal noise, intermodulation, crosstalk, and impulse noise all contribute unwanted signals that interfere with the received signal.
2) The maximum rate of error-free data transmission over a channel is called its channel capacity. It depends on the bandwidth, error rate tolerance, and transmission conditions. Network operators face challenges optimizing capacity utilization and traffic management to deliver quality of service within these constraints.
This document summarizes key information from chapters 8-10 of a homework assignment:
- It defines common digital signal rates like DS0, DS1, DS3, and OC-1 according to the North American digital hierarchy.
- It explains terms like DS0, DS1, and DS3 and what each is used for in digital signaling.
- It describes T-1 framing formats and where signaling information is carried.
- It explains the purpose of overhead bits in digital signals and how many DS0s are multiplexed into a T-1.
- It compares SONET bit rates like STS-1 to T-1 and T-3, explaining the difference between OC-
The document discusses various topics related to telecommunications including:
- The differences between an ILEC central office switch and a CLEC regional switch site.
- The purpose of a DSX panel and why two ports are required for connections.
- Standard sizes for relay racks and what DACs are used for.
- Key terms related to outside plant design like CSA, feeder cables, and distribution cables.
- Components of the local telephone network like load coils and T-1 repeater housings.
- Equipment used to determine fiber network endpoints like OTDRs.
- Functions of PBX systems and differences from key systems.
- Networking protocols, standards, and technologies discussed
Data Communications,Data Networks,computer communications,multiplexing,spread spectrum,protocol architecture,data link protocols,signal encoding techniques,transmission media,asynchronous transfer mode,routing,cellular networks
Modulation involves adding information to a carrier signal. There are two main types of modulation: analog and digital. Analog modulation varies either the amplitude (AM) or frequency (FM) of a carrier wave, while digital modulation uses techniques like amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK) to transmit digital data. Modems are used to transmit digital data over analog networks like phone lines by modulating and demodulating signals. Common modem types include internal, external, DSL, and cable modems.
Cellular networks divide geographic areas into cells served by low-power base stations to reuse frequencies. Adjacent cells are assigned different frequencies to avoid interference. As capacity demands increase, networks employ techniques like frequency borrowing, cell splitting, cell sectoring, and microcells. Cellular standards like GSM use TDMA to allow multiple users per cell by dividing the air interface into time slots. CDMA spreads user data over a wide bandwidth using unique codes and allows soft handoff between cells. Third generation networks support high-speed data and multimedia services.
A computer network connects devices using communication links. It allows for simultaneous communication and sharing of bandwidth between connected devices sending signals in either direction. There are different types of networks including personal area networks covering a single person, local area networks spanning a building or campus, metropolitan area networks covering multiple cities, and wide area networks spanning countries or continents. Networks rely on protocols that define rules for communication and different hardware technologies for data transmission, including broadcast links that send packets to all machines and point-to-point links that connect individual pairs of machines.
Introduction wireless communication networkRiazul Islam
The document provides an overview of wireless communications and networks. It discusses the history of wireless technologies and how digital communications provide noise immunity over analog signals. It also describes the basic components of a communication system including the transmitter, channel, and receiver. Additionally, it defines key terms related to wireless systems such as mobile station, base station, and handoff. The document outlines some examples of wireless communication systems and highlights challenges in wireless communications compared to wired systems.
This document provides an introduction to wireless communications and networks. It discusses the key components of a communication system including the source, transmitter, channel, receiver and output transducer. It also describes examples of wireless communication systems such as cellular telephone systems, remote controllers and wireless LANs. The document summarizes the characteristics of 1G, 2G and 3G wireless systems and standards. It also discusses wireless local area networks, personal area networks using Bluetooth, and mobile ad-hoc networks. Finally, it outlines the conceptual layers in a wireless network including the physical, data link, network and application layers.
Chapter 1 AI is used in Customer Relationship Management (CRM):.pptxfilembarketema
Certainly! Here are some examples of how AI is used in Customer Relationship Management (CRM):
Chatbots: AI-powered chatbots are used in CRM systems to provide automated customer support and assistance. Chatbots can handle a wide range of customer inquiries, answer frequently asked questions, and provide relevant information in real-time. They can engage in natural language conversations, understand customer intent, and provide personalized recommendations or solutions.
Sentiment Analysis: AI algorithms can analyze customer interactions, such as emails, social media posts, and chat transcripts, to determine customer sentiment and emotions. Sentiment analysis helps CRM systems understand customer satisfaction levels, identify potential issues or concerns, and take proactive measures to address them.
Personalization: AI enables CRM systems to deliver personalized experiences to customers. By analyzing customer data, purchase history, browsing behavior, and preferences, AI algorithms can generate personalized product recommendations, targeted marketing campaigns, and customized offers to enhance customer engagement and satisfaction.
Lead Scoring and Qualification: AI can assist in lead scoring and qualification processes. By analyzing historical data and customer behavior patterns, AI algorithms can predict the likelihood of a lead converting into a customer. This helps sales teams prioritize their efforts and allocate resources effectively to high-potential leads, improving conversion rates and sales efficiency.
Predictive Analytics: AI algorithms can analyze customer data and historical patterns to make predictions about customer behavior, such as likelihood to churn or cross-sell/up-sell opportunities. These predictions help CRM systems identify the most effective strategies for customer retention and revenue growth.
Voice and Speech Analytics: AI-powered voice and speech analytics tools can analyze customer calls and extract valuable insights. These tools can identify keywords, sentiment, and speech patterns to understand customer needs, identify common issues, and provide feedback for agent training and process improvement.
Social Media Monitoring: AI algorithms can monitor social media platforms to track brand mentions, customer feedback, and sentiment. This helps CRM systems identify customer concerns, engage in social listening, and respond promptly to customer queries or complaints, improving overall customer satisfaction and brand reputation.
Customer Segmentation: AI can assist in segmenting customers based on various criteria, such as demographics, purchase history, interests, and behavior. This enables CRM systems to tailor marketing campaigns, promotions, and communication strategies to specific customer segments, improving targeting and response rates.
Customer Lifetime Value (CLV) Prediction: This helps CRM
This document discusses telecommunication systems and communication networks. It covers three key points:
1) It describes the essential components of a communication system as a transmitting device, transport mechanism, and receiving device. The transport can range from a simple channel to a complex network.
2) It discusses different modes of transmission as simplex, duplex, and half duplex. Communications can be point-to-point, point-to-multipoint, or between many points.
3) It examines types of communication networks like the Public Switched Telephone Network (PSTN) and private automatic branch exchanges (PABX) that connect devices within an organization. The PSTN uses a switched network and signaling to set
This document discusses computer networking and communication. It defines networking as exchanging messages among parties, known as communication. Data communication consists of a sender, receiver, and medium. Communication can be simplex with one-way data flow, or duplex with two-way data flow. Wired media like twisted pair, coaxial cable, and fiber optics are guided, while wireless uses radio waves or infrared. Protocols govern digital data exchange within or between networks. Synchronization and acknowledgement ensure correct data transmission and reception. Signals carry data as electrical or electromagnetic currents. Modulation encodes digital data onto analog carrier signals for transmission.
This document summarizes information about Bharat Sanchar Nigam Limited (BSNL), the seventh largest telecommunications company in the world. It provides an overview of BSNL's services and sections within telephone exchanges, including the main distribution frame room, power room, PCM room, switch room, optical fiber cable section, broadband section, and mobile section. It also describes technologies used like DWDM, signaling, PDH and SDH multiplexing hierarchies, and defines key terms like STM.
This document discusses key concepts in communication systems including:
1) The basic elements of a communication system including the information source, transmitter, channel, and receiver.
2) Types of communication including simplex, full duplex, and half duplex as well as analog and digital signals.
3) Modulation and multiplexing which allow signals to be transmitted efficiently over a channel by modifying the signal or combining multiple signals.
Cellular network evolved gradually .Generations of computer network like 1st generation (1g) ,second generation (2g) evolved .Then came 3g ,4g, each time with increased speed and security
This document provides an introduction to electronic communication systems. It discusses the basic elements of a communication system including the information source, transmitter, channel, receiver and destination. It also classifies communication systems as either analog or digital. Modulation techniques are described which allow baseband signals to be transmitted over a channel by modifying a carrier signal. The document outlines some fundamental limitations of communication systems including noise, distortion and bandwidth. It discusses different types of signal distortion and techniques for equalization and companding to overcome nonlinear distortion.
Telecommunication involves the transmission of information using technology. It has basic elements including a transmitter, transmission medium, and receiver. Telecommunication occurs through various channels and technologies like telephone networks, cellular networks, and the internet. Common concepts include modulation, multiplexing, circuit switching, and packet switching. Modern cellular technologies progression includes 2G, 3G, LTE, and VoLTE networks that provide improved data speeds and services. ADSL uses frequencies on copper telephone lines to provide faster internet speeds than traditional modems.
Cellular networks use multiple low-power transmitters that divide coverage areas into cells served by individual antennas and base stations. Adjacent cells are assigned different frequencies to avoid interference. As capacity demands increase, networks address this through techniques like frequency borrowing, cell splitting, and adding microcells. Digital cellular systems like GSM use TDMA to allow dynamic channel sharing between users. GSM networks feature a mobile station that communicates through the base station subsystem and network subsystem, which includes HLR, VLR, and MSC databases to manage authentication, location tracking, and call routing.
A communications system allows for the transfer of information from an information source to an information sink. It consists of a transmitter that encodes a message from the information source into a transmitted signal, a channel to carry the signal, and a receiver to decode the signal back into a message for the information sink.
The transmitter may perform operations like modulation, amplification, and filtering on the message signal. The channel can be a wireline medium like coaxial cable or a wireless medium like free space. It is subject to degradation from noise, interference and distortion. The receiver performs complementary operations to the transmitter like demodulation, amplification and filtering to recover the original message from the received signal for the information sink.
Mobile communication - GSM/CDMA/WIMAX TechnologiesAman Abhishek
Mobile communication allows communication without a physical connection and flexibility to move anywhere during communication. It uses technologies like GSM and CDMA. Mobile communication has become one of the fastest growing industries. A mobile handset allows making and receiving calls over radio links while moving. It contains components like a battery, SIM card and antenna. A SIM card identifies the subscriber to the network. In mobile communication, a cell is the smallest area, subscribers pay for use, and base stations connect mobile units to switching centers. As users move, handoffs transfer calls between base stations to maintain connectivity.
Lesson 4 communication and computer network (123 kb)IMRAN KHAN
Communication between computers has increased with advancements in data communication facilities, allowing users to access computers remotely. A computer network connects multiple computers over communication channels to share data and programs across geographical locations. It consists of senders and receivers of messages connected by a medium like cables, wireless signals, or satellites. Protocols define how computers transmit data over the network by sequencing packets, routing them efficiently, and detecting and correcting errors.
Communication channel and networktechnologies.pdfmouizakhan4
1) The document discusses various topics related to telecommunication systems including communication channels, signals, and network components. It describes how speech signals are converted to electrical forms and transmitted over channels.
2) The communication channel acts as a conduit between the transmitter and receiver. Impairments like noise, attenuation and bandwidth limitations can degrade signals during transmission.
3) A communication system requires a transmitting device, transport mechanism, and receiving device to effectively transfer information. Networks facilitate communication between users across geographical boundaries using various transmission media and standards.
Wireless communication involves transmitting information such as voice and data through electromagnetic waves without wires. It allows for flexible and mobile connectivity between devices. The document discusses various topics related to wireless communication including point-to-point communication, multiuser systems, modulation techniques, channel models and capacity. It provides an overview of the evolution of wireless technologies and applications.
The document provides an overview of the Global System for Mobile Communication (GSM) standard. It describes GSM as an integrated European mobile system that enables international roaming. The key objectives of GSM are outlined as well as the basic system elements, including mobile stations, base station systems, and mobile switching centers. The document also discusses concepts such as frequency reuse, cellular networks, handover, and multiple access methods used in GSM like TDMA.
The document discusses digital modulation techniques used in modern telecommunication systems. It describes techniques like ASK, FSK, PSK and QAM that are used to modulate digital signals for transmission. It also discusses multiplexing techniques like FDM and TDM that allow multiple signals to be transmitted simultaneously over the same medium. The document outlines the evolution from analog to digital networks, including the introduction of techniques like PCM, TDM and optical fiber that enabled widespread digitization of telecom networks and improved quality, features and costs.
The document discusses cellular communication systems and mobile network technologies including:
- The basic components and principles of cellular networks including cells, frequency reuse, and handoff.
- Early analog cellular standards like AMPS and their limitations in capacity and features.
- Digital cellular standards including TDMA, CDMA, and GSM, with details on GSM network architecture and services.
- 3G networks providing broadband multimedia including messaging, applications, and requirements.
- Challenges include handover, screen size, functionality for convergence of mobile and consumer electronics.
This document discusses error detection and correction techniques used at the data link layer. It describes different types of errors that can occur like single-bit and burst errors. Error detection methods like parity checks, cyclic redundancy checks (CRC), and checksums are explained. Forward error correction codes like Hamming codes that allow for error correction are also covered. The document provides examples to illustrate how various error detection and correction schemes work.
The document discusses several existing wireless systems including Advanced Mobile Phone System (AMPS), Global System for Mobile communications (GSM), and IS-41 standard. AMPS was one of the first cellular standards and uses FM to transmit voice and FSK for control signals. It divides coverage areas into cells using different frequency bands. GSM is a second-generation standard that aims for roaming between networks. It uses TDMA and operates between 890-960 MHz. IS-41 allows for roaming and handoffs between mobile switching centers.
The document describes the infrastructure and processes that enable cellular communication systems. Key components include:
- Base stations that transmit and receive signals and connect to a base station controller.
- Authentication centers and equipment registers that verify user identities and equipment.
- Home and visitor location registers that track user locations to route calls and support mobility.
- Registration and handoff processes allow users to move between base stations and be reached on their cell phone number anywhere on the network. Location tracking, signaling between registers, and rerouting enable seamless roaming across large areas.
The document discusses network protocols and the OSI model. It describes the 7 layers of the OSI model from the physical layer to the application layer. It then discusses the TCP/IP protocol suite and its 5 layers. For each layer, it outlines the main responsibilities and protocols that are part of that layer such as IP, ICMP, DHCP, TCP, and others. It also discusses some common routing protocols like RIP, OSPF, and BGP. Finally, it covers issues with using TCP over wireless networks and some proposed solutions to improve its performance.
The document discusses various multiple access techniques used in wireless networks. It describes Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA), Orthogonal Frequency Division Multiplexing (OFDM), and Space Division Multiple Access (SDMA). It also covers concepts like duplexing methods, power control, modulation techniques, and the near-far problem in CDMA systems.
Mobile stations must share a single channel for communication, which can lead to collisions if multiple stations transmit simultaneously. Several protocols have been developed to manage access to the shared channel, including ALOHA, CSMA, and their variations. CSMA/CA with RTS/CTS is commonly used in wireless networks as it helps avoid collisions and resolve the hidden terminal problem.
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A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
This presentation was provided by Steph Pollock of The American Psychological Association’s Journals Program, and Damita Snow, of The American Society of Civil Engineers (ASCE), for the initial session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session One: 'Setting Expectations: a DEIA Primer,' was held June 6, 2024.
Exploiting Artificial Intelligence for Empowering Researchers and Faculty, In...Dr. Vinod Kumar Kanvaria
Exploiting Artificial Intelligence for Empowering Researchers and Faculty,
International FDP on Fundamentals of Research in Social Sciences
at Integral University, Lucknow, 06.06.2024
By Dr. Vinod Kumar Kanvaria
LAND USE LAND COVER AND NDVI OF MIRZAPUR DISTRICT, UPRAHUL
This Dissertation explores the particular circumstances of Mirzapur, a region located in the
core of India. Mirzapur, with its varied terrains and abundant biodiversity, offers an optimal
environment for investigating the changes in vegetation cover dynamics. Our study utilizes
advanced technologies such as GIS (Geographic Information Systems) and Remote sensing to
analyze the transformations that have taken place over the course of a decade.
The complex relationship between human activities and the environment has been the focus
of extensive research and worry. As the global community grapples with swift urbanization,
population expansion, and economic progress, the effects on natural ecosystems are becoming
more evident. A crucial element of this impact is the alteration of vegetation cover, which plays a
significant role in maintaining the ecological equilibrium of our planet.Land serves as the foundation for all human activities and provides the necessary materials for
these activities. As the most crucial natural resource, its utilization by humans results in different
'Land uses,' which are determined by both human activities and the physical characteristics of the
land.
The utilization of land is impacted by human needs and environmental factors. In countries
like India, rapid population growth and the emphasis on extensive resource exploitation can lead
to significant land degradation, adversely affecting the region's land cover.
Therefore, human intervention has significantly influenced land use patterns over many
centuries, evolving its structure over time and space. In the present era, these changes have
accelerated due to factors such as agriculture and urbanization. Information regarding land use and
cover is essential for various planning and management tasks related to the Earth's surface,
providing crucial environmental data for scientific, resource management, policy purposes, and
diverse human activities.
Accurate understanding of land use and cover is imperative for the development planning
of any area. Consequently, a wide range of professionals, including earth system scientists, land
and water managers, and urban planners, are interested in obtaining data on land use and cover
changes, conversion trends, and other related patterns. The spatial dimensions of land use and
cover support policymakers and scientists in making well-informed decisions, as alterations in
these patterns indicate shifts in economic and social conditions. Monitoring such changes with the
help of Advanced technologies like Remote Sensing and Geographic Information Systems is
crucial for coordinated efforts across different administrative levels. Advanced technologies like
Remote Sensing and Geographic Information Systems
9
Changes in vegetation cover refer to variations in the distribution, composition, and overall
structure of plant communities across different temporal and spatial scales. These changes can
occur natural.
This slide is special for master students (MIBS & MIFB) in UUM. Also useful for readers who are interested in the topic of contemporary Islamic banking.
How to Setup Warehouse & Location in Odoo 17 InventoryCeline George
In this slide, we'll explore how to set up warehouses and locations in Odoo 17 Inventory. This will help us manage our stock effectively, track inventory levels, and streamline warehouse operations.
2. Overview of a Communication System
Digital vs. Analog Communications
Examples of Wireless Communication Systems
Why Wireless is Different ?
Wireless System Architecture
Multiple Access Techniques
Evolution of Cellular Networks (1G ~ 4G)
Wireless Local Area Networks (WLANs), Bluetooth and
Personal Area Networks (PANs)
Ad hoc networks
Cellular Concepts
Outline
4. The source originates a message, which could be a human voice, a
television picture or data. The source is converted by an input
transducer into an electrical waveform referred to as the baseband
signal or message signal.
The transmitter modifies the baseband signal for efficient
transmission. The transmitter generally consists of one or more of the
following subsystems: a pre-emphasizer, a sampler, aquantizer, a
coder and a modulator.
The channel is a medium through which the transmitter output is
sent, which could be a wire, a coaxial cable, an optical fiber, or a radio
link, etc. Based on the channel type, modern communication systems
are divided into two categories: wireline communication systems and
wireless communication systems.
Components of a
Communication System (2)
5. The receiver reprocessed the signal received from the channel
by undoing the signal modifications made at the transmitter
and the channel. The task of the receiver is to extract the
message from the distorted and noisy signal at the channel
output. The receiver may consist of a demodulator, a decoder, a
filter, and a de-emphasizer.
The receiver output is fed to the output transducer, which
converts the electrical signal to its original form.
Transmitters and receivers are carefully designed to overcome
the distortion and noise. The Goal of Physical layer
Communication System is to transmit information accurately
and efficiently(power and spectrum).
Components of a
Communication System (3)
6. Analog and Digital Signals
Messages are digital or analog.
Digital messages are constructed with a finite number of
symbols. For example, a text file is a digital message
constructed from 50 symbols, consists of 26 letters, 10
numbers, a space and several punctuation marks. Similarly, a
Morse-coded telegraph is a binary message, implying only
two symbols –mark and space.
Analog messages are characterized by data whose values vary
over a continuous range. For example, a speech waveform has
amplitudes that vary over a continuous range. A picture is also
an analog message.
Digital vs. Analog
Communications (1)
8. Noise immunity of digital signals–digital data can be recovered
without any error as long as the distortion and noise are within limits .
On the other hand, for an analog message, even a slight distortion or
interference in the waveform will cause an error in the received signal.
Regenerative repeaters––Based on this “noise immunity”, when
transporting a bit stream over a long distance, regenerative repeaters
or repeater stations are placed along the path of a digital system at
distances short enough to ensure that noise and distortion remain
within a limit. The viability of regenerative repeaters is the main reason
for the superiority of digital systems over analog ones.
Every possible communication can be carried on with a minimum of
two symbols, i.e., by using a proper binary sequence. In the last 20
years, digital communication gradually replace its analog competitors,
and the revolution is now nearly complete.
Digital vs. Analog
Communications (2)
9. Sampling Theorem A meeting ground exists for analog and digital
signals: conversion of analog signals to digital signals. The backbone
that supports the interface is Shannon's Sampling Theorem, which states
that if the highest frequency in the signal spectrum is B (in hertz), then
the signal can be recovered from its samples, taken at a rate not less
than 2B samples per second.
Quantization each sample is approximated, or round off to the nearest
quantized level, the information is thus digitalized. The quantized signal
is an approximation of the original one. We can improve the accuracy of
the quantized signal to any desired degree by increasing the number of
levels.
Coding
Source coding Convert the quantized signal into binary sequences.
Channel coding Introduce redundancy in a controlled manner to
overcome the effects of noise and interferences.
Mapping Map binary sequence into symbols.
Transmission Symbols are applied to a transmitter filter, which produces
a continuous signal for transmission over a continuous channel.
Interface of Analog and Digital
Systems -A/D and D/A Conversion
10. Codeless telephones ---use radio to connect a portable handset to a
dedicated base station over a distance of a few tens of meters.
Paging systems ---Communication systems that broadcast a page from
every base station in the network and send brief messages to a
subscriber.
Cellular telephone systems ---provide a wireless connection to the
PSTN (Public Switched Telephone Network) for any user location
within the radio range of a system.
Garage car opener
Remote controllers for home entertainment equipment
Hand-held walkie-talkies
Wireless keyboard and mouse
Wireless Lan router and adapter
…..
Examples of Wireless
Communication Systems
11. Wireless channel
Have time varying and multipath propagation properties.
Communicate over a medium significantly less reliable than wired physical
layer.
Are unprotected from outside signals and interceptions. Multiuser
interference (MUI) is a significant problem in wireless communications.
Has neither absolute nor readily observable boundaries outside of which
stations are known to be unable to receive network frames.
User Mobility
Destination address does not equal to a fixed destination location.
Power management ---performance, interference lever and power
consumption.
Hand-off ---A mobile switches its serving base station while moving from cell
to cell.
Location management ---tracks the user’s movement, support users roaming
delivers calls to the user at its current location.
Wireless Vs. Wireline Communications -
Challenges in Wireless Communication
Systems
12. Rapid growth In the last few
decades, new and cheaper
wireless services are emerging
continuously, due to advances in:
Digital signal processing
Digital and RF circuit fabrication
Large scale circuit integration
Digital switching techniques ->
large scale deployment of radio
communication networks
Convergence of wireless and
Internet ----Broadband
communications
3G cellular and PCS networks
WLAN networks
Ad-hoc Networks (military)
Trends on Wireless
Communications
14. Radio Access: RF related signal processing and radio resource
management. Mobile => base station => BSC or RNC => MSC.
Core Network: Main part is MSC (mobile switching center),
performs user authentication, admission control, traffic control,
roaming, billing, network support and maintenance etc.
Backbone networks: Providing voice services (PSTN, Public
Switched Telephone Network), data services (through
Internet), and emergency services. Wireless networks need to
be connected to backbone networks to extend its service
capabilities and geographic coverage.
Cellular System Architecture
15. FDMA(Frequency Division Multiple Access) each user is
allocated a unique frequency band or channel, no other user
can share the same frequency band.
TDMA (Time Division Multiple Access)
divides the radio spectrum into time slots,
and in each slot, only one user is allowed
to either transmit or receive.
Multiple Access Techniques
16. CDMA (Code Division Multiple Access)
each user is assigned a special code
sequence (signature) to modulate its
message signal, all users are allowed to
transmit over the same channel
simultaneously and asynchronously.
OFDMA (Orthogonal frequency division
multiple access) Allows multiple users to
access the same channel at the same time.
Current WLANs such as IEEE 802.11a/g/n and
IEEE 802.16d (fixed service) are based on
OFDM, while WiMAX such as IEEE 802.16e
(mobile service) uses OFDMA.
SDMA (Space Division Multiple
Access) controls the radiated energy
for each user in space. SDMA serves
different users by using spot beam
antennas.
Multiple Access Techniques
17. Receiving a call
Turn on a cellular phone
The cellular phone scan the control channels to determine the one with the
strongest signal, it then monitors the signal drops below a usable level. At
his point, it starts to search of strongest base station again.
If a phone call is placed to a mobile user, the MSC dispatches the request to
all the base stations in the system, the MIN (mobile identification number,
i.e. the mobile’s phone number) is broadcast as a paging message through
the forward control channel.
The mobile receives the signal through the base station it monitors and
responds by identifying itself through the reverse control channel.
The base station informs the MSC of the handshake.
The MSC instructs the base station to move the call to an unused voice
channel within the cell.
The base station signals the mobile to change frequencies to the unused
unused forward and reverse voice channel pair.
The base station instructs the mobile phone to ring, thereby to instruct the
user to answer the phone.
How a cellular telephone call is
made?
18. Initiating a call
The mobile sends a call initiation request through the reverse control channel,
with this the unit transmits its MIN, ESN (electronic serial number) and the
phone number of the called party.
Base station receives the request and sends it to the MSC.
The MSC validates the request, making connection to the called party through
PSTN.
The MSC instructs the base station and mobile user to move to an unused
forward and reverse voice channel pair.
Roaming
All cellular systems provide a service called roaming. This allows subscribers to
operate in service areas other than the one from which the service is subscribed.
The MSC issues a global command every several minutes, asking all unregistered
mobiles to report their subscription information.
Mobiles report back upon receiving the request.
If the mobile has roaming authorization for billing purpose, the MSC registers
the subscriber as a roamer.
How a cellular phone call is
made (continued)
28. 4G = 4th Generation mobile communications.
4G = B3G = Beyond 3rd Generation (UMTS, IMT-2000) mobile
Communications.
Foreseen to become available after 2010.
A 4G system will provide an end-to-end IP solution where voice, data
and streamed multimedia can be served to users on an "Anytime,
Anywhere" basis at higher data rates than previous generations.
ITU Recommandation ITU-R M.1645:
Systems beyond IMT-2000 will be realized by functional fusion of existing,
enhanced, and newly developed elements of IMT-2000, nomadic wireless
access systems and other wireless systems, with high commonality and
seamless interworking.
Targeted data rates (with wide area coverage and significant mobility)
= 50 to 100 Mbits/s.
Wider bandwidth;
End-to-end Quality of service ;
High security;
Offering any kind of services anytime, anywhere;
Affordable cost and one billing.
4G – what it is ?
29. WiMAX 802.16e,
WiBro
IEEE 802.20 3GPP LTE
Key technology OFDMA, MIMO OFDMA, MIMO OFDMA/SC-FDMA,
MIMO
Duplex TDD/FDD TDD/FDD TDD/FDD
Channel Bandwidth 10 MHz 5 ~ 20 MHz 1.25 ~ 20 MHz
Mobility Middle High (~250 Km/h) High (~250 Km/h)
Peak Data
Rate
DL 46 Mbps 260 Mbps 100 Mbps
UL 14 Mbps 60 Mbps 50 Mbps
Coverage 2 ~ 5Km (typical) MAN scale < 20km, WAN scale
Frequency Band 2 ~ 6GHz Below 3.5 GHz WCDMA band with
additional band
Commercial ready 2007 ~ 2008 unexpected 2009 ~ 2010
29
Different radio access technologies for
4G
30. Attribute 3G 4G
Major Characteristic Predominantly voice- data as add-on Converged data and VoIP
Network Architecture Wide area Cell based
Hybrid – integration of Wireless
Lan (WiFi), Blue Tooth, Wide Area
Frequency Band 1.6 - 2.5 GHz 2 – 8 GHz
Component Design Optimized antenna; multi-band adapters
Smart antennas; SW multi-band;
wideband radios
Bandwidth 5 – 20 MHz 100+ MHz
Data Rate 385 Kbps - 2 Mbps 20 – 100 Mbps
Access WCDMA/CDMA2000 MC-CDMA or OFDM
Forward Error Correction Convolution code 1/2, 1/3; turbo Concatenated Coding
Switching Circuit/Packet Packet
Mobile top Speed 200 kmph 200 kmph
IP Multiple versions All IP (IPv6.0)
Operational ~2003 ~2010
30
Comparing 3G vs 4G
31.
32. An ad hoc (also written ad-hoc or adhoc) network is a local network with
wireless or temporary plug-in connection, in which mobile or portable devices
are part of the network only while they are in close proximity.
Future military applications for ad hoc networks, which include a group of
soldiers in close proximity sharing information on their notebook computers
using RF signals, along with numerous commercial applications, are now being
explored.
A mobile ad hoc network (MANET) is an autonomous system of mobile nodes,
mobile hosts (MHs), or MSs (also serving as routers) connected by wireless
links, the union of which forms a network modeled in the form of an arbitrary
communication graph. The routers are free to move at any speed in any
direction and organize themselves randomly.
Thus, the network’s wireless topology may dynamically change in an
unpredictable manner. There is no fixed infrastructure, and information is
forwarded in peer-to-peer (p2p) mode using multihop routing.
“an ad hoc network is a collection of wireless MHs
forming a temporary network without the aid of any
centralized administration or standard support
services regularly available on the wide area network
to which the hosts may normally be connected.”
Ad Hoc Networks
Illustration of
frequency hopping.
33. A mobile ad hoc network (MANET) are
finding an increased use as a Vehicular
Area Network (VANET). This is especially
true in urban areas where presence of
an internet on streets is impossible and
needed assistance and other useful
information can be shared with users
using MANETs among vehicles on the
road.
Sensor networks are the newest
members of one special class of wireless
ad hoc networks wherein a large
number of tiny immobile sensors are
planted on an ad hoc basis to sense and
transmit some physical characteristics
of the environment.
An associated BS collects the
information gathered by the sensors on
a data-centric basis. Although tiny
sensors are yet to be produced on a
large scale, people are exploring their
usefulness in many application areas.
Sensor Networks
34.
35. A cell is formally defined as an area wherein the use of radio
communication resources by the MS is controlled by a BS.
The size and shape of the cell and the amount of resources
allocated to each cell dictate the performance of the system to
a large extent, given the number of users, average frequency of
calls being made, average duration of call time, and so on.
Cell Area In a cellular system, the most important factor is the
size and the shape of a cell.
Cellular Concept
36. Handoff The variation of received power as a function of distance is given in
Figure 5.4. As the MS moves away from the BS of the cell, the signal strength
weakens, and at some point. region X3 to X4 indicates the handoff area.
MS moves away from cell i and gets closer to cell j . Assuming that Pi (x) and Pj
(x) represent the power received at the MS from BSi and BSj , the received signal
strength at the MS can be approximated by curves shown in Figure 5.5 .At
distance X1, the received signal from BSj is close to zero and the signal strength
at the MS can be primarily attributed to BSi .
Signal Strength and Cell Parameters 2