This document discusses wireless communication channels and diversity techniques. It describes how wireless channels experience both large-scale and small-scale fading, unlike wired channels. Small-scale fading is caused by multipath interference and results in rapid channel variations. Diversity combines multiple independent copies of the signal to improve link performance over fading channels. It can be achieved through techniques like antenna, site, frequency, time, polarization and angle diversity. The capacity of wireless channels is fundamentally limited by information theory based on available channel resources.
It is description about trunking theory that is used to develop trunked system that can allocate a limited number of channels to a large number of users.
QAM modulation is a combination of Amplitude Shift Keying and Phase Shift Keying, both carrier wave is modulated by changing both its amplitude and phase...
It is description about trunking theory that is used to develop trunked system that can allocate a limited number of channels to a large number of users.
QAM modulation is a combination of Amplitude Shift Keying and Phase Shift Keying, both carrier wave is modulated by changing both its amplitude and phase...
SPACE DIVISION MULTIPLE ACCESS (SDMA) SATELLITE COMMUNICATION Soumen Santra
SPACE DIVISION MULTIPLE ACCESS (SDMA)
Definition : The communication channel encountered by this array of antennas.
advanced antenna technology.
Smart Antenna
Uplink Transmission
Downlink Transmission
Block Diagram
Features
Beam Frequency Reuse
Advantages
Disadvantages
Examples of wireless communication systems, paging systems, cordless telephone systems, cellular telephone systems,evolution of mobile phone, MSC, MTSO, PSTN, Mobile communication, wireless link, subscriber,
Physical channel - Each timeslot on a carrier is referred to as a physical channel. Per carrier there are 8 physical channels.
Logical channel - Variety of information is transmitted between the MS and BTS. There are different logical channels depending on the information sent. The logical channels are of two types
Traffic channel
Control channel
BCH Channels
BCCH( Broadcast Control Channel )
Downlink only
Broadcasts general information of the serving cell called System Information
BCCH is transmitted on timeslot zero of BCCH carrier
Read only by idle mobile at least once every 30 secs.
SCH( Synchronisation Channel )
Downlink only
Carries information for frame synchronisation. Contains TDMA frame number and BSIC.
FCCH( Frequency Correction Channel )
Downlink only.
Enables MS to synchronise to the frequency.
Also helps mobiles of the ncells to locate TS 0 of BCCH carrier.
RACH( Random Access Channel )
Uplink only
Used by the MS to access the Network.
AGCH( Access Grant Channel )
Downlink only
Used by the network to assign a signalling channel upon successfull decoding of access bursts.
PCH( Paging Channel )
Downlink only.
Used by the Network to contact the MS.
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
SPACE DIVISION MULTIPLE ACCESS (SDMA) SATELLITE COMMUNICATION Soumen Santra
SPACE DIVISION MULTIPLE ACCESS (SDMA)
Definition : The communication channel encountered by this array of antennas.
advanced antenna technology.
Smart Antenna
Uplink Transmission
Downlink Transmission
Block Diagram
Features
Beam Frequency Reuse
Advantages
Disadvantages
Examples of wireless communication systems, paging systems, cordless telephone systems, cellular telephone systems,evolution of mobile phone, MSC, MTSO, PSTN, Mobile communication, wireless link, subscriber,
Physical channel - Each timeslot on a carrier is referred to as a physical channel. Per carrier there are 8 physical channels.
Logical channel - Variety of information is transmitted between the MS and BTS. There are different logical channels depending on the information sent. The logical channels are of two types
Traffic channel
Control channel
BCH Channels
BCCH( Broadcast Control Channel )
Downlink only
Broadcasts general information of the serving cell called System Information
BCCH is transmitted on timeslot zero of BCCH carrier
Read only by idle mobile at least once every 30 secs.
SCH( Synchronisation Channel )
Downlink only
Carries information for frame synchronisation. Contains TDMA frame number and BSIC.
FCCH( Frequency Correction Channel )
Downlink only.
Enables MS to synchronise to the frequency.
Also helps mobiles of the ncells to locate TS 0 of BCCH carrier.
RACH( Random Access Channel )
Uplink only
Used by the MS to access the Network.
AGCH( Access Grant Channel )
Downlink only
Used by the network to assign a signalling channel upon successfull decoding of access bursts.
PCH( Paging Channel )
Downlink only.
Used by the Network to contact the MS.
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
Welcome to TechSoup New Member Orientation and Q&A (May 2024).pdfTechSoup
In this webinar you will learn how your organization can access TechSoup's wide variety of product discount and donation programs. From hardware to software, we'll give you a tour of the tools available to help your nonprofit with productivity, collaboration, financial management, donor tracking, security, and more.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
Synthetic Fiber Construction in lab .pptxPavel ( NSTU)
Synthetic fiber production is a fascinating and complex field that blends chemistry, engineering, and environmental science. By understanding these aspects, students can gain a comprehensive view of synthetic fiber production, its impact on society and the environment, and the potential for future innovations. Synthetic fibers play a crucial role in modern society, impacting various aspects of daily life, industry, and the environment. ynthetic fibers are integral to modern life, offering a range of benefits from cost-effectiveness and versatility to innovative applications and performance characteristics. While they pose environmental challenges, ongoing research and development aim to create more sustainable and eco-friendly alternatives. Understanding the importance of synthetic fibers helps in appreciating their role in the economy, industry, and daily life, while also emphasizing the need for sustainable practices and innovation.
Acetabularia Information For Class 9 .docxvaibhavrinwa19
Acetabularia acetabulum is a single-celled green alga that in its vegetative state is morphologically differentiated into a basal rhizoid and an axially elongated stalk, which bears whorls of branching hairs. The single diploid nucleus resides in the rhizoid.
Honest Reviews of Tim Han LMA Course Program.pptxtimhan337
Personal development courses are widely available today, with each one promising life-changing outcomes. Tim Han’s Life Mastery Achievers (LMA) Course has drawn a lot of interest. In addition to offering my frank assessment of Success Insider’s LMA Course, this piece examines the course’s effects via a variety of Tim Han LMA course reviews and Success Insider comments.
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
The Roman Empire’s society was hierarchical, with a rigid class system. At the top were the patricians, wealthy elites who held significant political power. Below them were the plebeians, free citizens with limited political influence, and the vast numbers of slaves who formed the backbone of the economy. The family unit was central, governed by the paterfamilias, the male head who held absolute authority.
Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
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1.4 modern child centered education - mahatma gandhi-2.pptx
The wireless channel, diversity and capacity of wireless channels
1. THE WIRELESS CHANNEL, DIVERSITY
AND CAPACITY OF WIRELESS CHANNELS
Presented By:
Faiz.ur.Rehman
MS(CS)
faiz.rehmanpk@yahoo.com
2. CONTENTS
Communication channel
The wire line channel
The wireless channel
Fading effect
Large scale fading
Small scale-multipath fading
Diversity
Capacity of wireless channels
Methods for obtaining multiple replicas
4. THE WIRE LINE CHANNEL
Transmitter Receiver
Wireline Channel,
e.g. copper wire
Too many noises?
Shielded against
electromagnetic noise
Large signal attenuation?
Use repeaters
Data speed too low? Upgrade to coaxial cable
Data speed still too low?
Upgrade to optical fiber
5. THE WIRELESS CHANNEL
Channel varies at two spatial scales:
large scale fading
small scale fading
6. FADING EFFECT
Typical Indoor
Wireless
Environment
Signal strength
fluctuates
significantly
Wireless channel
cannot be
engineered.
You can only
improve your
transmission and
reception
techniques.
7. LARGE-SCALE FADING
In free space, received power attenuates like 1/r2.
( r => radius )
With reflections and obstructions, can attenuate
even more rapidly with distance. Detailed modeling
complicated.
Time constants associated with variations are very
long as the mobile moves, many seconds or
minutes.
More important for cell site planning, less for
communication system design.
8. SMALL-SCALE MULTIPATH FADING
Wireless communication typically happens at very high
carrier frequency. (e.g. fc = 900 MHz or 1.9 GHz for
cellular)
Multipath fading due to constructive and destructive
interference of the transmitted waves.
Channel varies when mobile moves a distance of the order
of the carrier wavelength. This is 0.3m for GHz cellular.
For vehicular speeds, this translates to channel variation of
the order of 100 Hz.
Primary driver behind wireless communication system
design.
9. What is diversity?
Diversity is a technique to combine several copies of
the same message received over different channels.
Why diversity?
To improve link performance.
DIVERSITY
10. DIVERSITY
Communication over a flat fading channel has poor
performance due to significant probability that channel is
in deep fading.
Reliability is increased by providing more signal paths
that fade independently.
Diversity can be provided across time, frequency and
space.
11. CAPACITY OF WIRELESS CHANNELS
Information Theory (1948):
Information theory says every channel has a capacity.
Information theory provides a fundamental characterization
of coded performance.
It identifies the impact of channel resources on performance
as well as suggests new and cool ways to communicate over
the wireless channel.
It provides the basis for the modern development of wireless
communication.
12. METHODS FOR OBTAINING MULTIPLE
REPLICAS
• Antenna Diversity
• Site Diversity
• Frequency Diversity
• Time Diversity
• Polarization Diversity
• Angle Diversity
Editor's Notes
Large-scale fading, due to path loss of signal as a function of distance and shadowing by large objects such as buildings and hills. This occurs as the mobile moves through a distance of the order of the cell size, and is typically frequency independent.
Small-scale fading, due to the constructive and destructive interference of the multiple signal paths between the transmitter and receiver. This occurs at the spatial scale of the order of the carrier wavelength, and is frequency dependent.
A signal transmitted at a particular carrier frequency and at a particular instant of time may be received in a multipath null. Diversity reception reduces the probability of occurrence of communication failures (outages) caused by fades by combining several copies of the same message received over different channels.
Fading: In wireless communications, fading is deviation of the attenuation affecting a signal over certain propagation media.
Flat fading: In flat fading, the coherence bandwidth of the channel is larger than the bandwidth of the signal. Therefore, all frequency components of the signal will experience the same magnitude of fading.
Deep fading: Strong destructive interference is frequently referred to as a deep fade and may result in temporary failure of communication due to a severe drop in the channel signal-to-noise ratio.
The terms slow and fast fading refer to the rate at which the magnitude and phase change imposed by the channel on the signal changes. The coherence time is a measure of the minimum time required for the magnitude change of the channel to become uncorrelated from its previous value.
Information theory in 1948
Information theory says every channel has a capacity.
Many recent advances based on understanding wireless channel capacity.
While
Wireless communication has been around since 1900’s.
Ingenious but somewhat adhoc design techniques
In antenna (or micro) diversity the signal from antennas mounted at separate locations are combined. Typically these antennas are located on the vehicle or at the same base station tower and their spacing is a few wavelengths.
In site (or macro) diversity the receiving antennas are located at different receiver sites. For instance, signals from within a cell may be received at the different corners of the hexagonal area. The advantage is that not only the multipath fading attenuation is independent at each branch but that the shadowing and path losses are also uncorrelated to some extent.
In Frequency diversity, Each message is transmitted at different carrier frequencies simultaneously. Frequency separation >> coherence bandwidth
In time diversity, the time difference between two transmissions should be large compared to the time is takes the mobile antenna to move half a wavelength. In systems with stationary antennas, such as indoor wireless communication, time diversity will be less effective as the channel characteristics do not change very much with time.
Polarization diversity exploits the fact that obstacles scatter waves differently depending on their polarization. It is hoped that in (at least) one of the branches the received waves do not cancel each other, resulting in a relatively strong signal.
In Angle Diversity, In angle diversity, directional antennas receive only a fraction of all scattered energy. Waves from different angles of arrival are combined optimally, rather than with random phase.