multiple access for wireless mobile communications
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Subject: wireless mobile communication. Topics covered : FDMA, TDMA , Spread Spectrum Multiple Access,Space Division Multiple Access,Capacity of Cellular systems
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2.3 time division multiple access
TDMA divides the radio spectrum into time slots and allows only one user to transmit or receive data during each time slot. It uses a buffer-and-burst transmission method, making it well-suited for digital systems. TDMA systems employ TDMA/TDD or TDMA/FDD for duplexing and multiple access. A TDMA frame includes a preamble for identification and synchronization, and multiple time slots containing user data, trail bits, and guard bits between slots. TDMA provides high transmission rates, simpler handoff, and is more cost-effective than FDMA, though it requires minimum guard times between slots to avoid interference.
2.6 cellular concepts - frequency reusing, channel assignment
- Cellular networks address the problem of limited spectrum availability by using frequency reuse, where nearby base stations are assigned different channels to avoid interference. Cells are arranged in a hexagonal pattern and the same set of channels are reused in cells sufficiently far from each other.
- There are two main channel assignment strategies - fixed assignment, where each cell has a predetermined set of channels, and dynamic assignment, where channels are allocated on demand by a central controller considering interference levels. Dynamic assignment helps improve spectrum utilization but requires more complex coordination.
- Frequency reuse allows the available spectrum to be reused as needed across multiple cells as long as interference is kept at acceptable levels, increasing network capacity.
2.4 code division multiple access
This document discusses different multiple access techniques used in wireless communication systems. It provides details about Code Division Multiple Access (CDMA) including: how CDMA uses pseudorandom codes and spreading signals to allow simultaneous transmission from multiple users; the need for orthogonal codes to minimize interference; and challenges like near-far problem when power levels differ between users. It also compares CDMA with Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA), listing pros and cons of CDMA, and how its capacity depends on interference level rather than bandwidth.
Chapter 7 multiple access techniques
Multiple access techniques allow multiple users to share finite radio spectrum resources simultaneously. They can be categorized as narrowband or wideband. Common techniques include FDMA, TDMA, CDMA, and SDMA. FDMA divides the total bandwidth into narrow channels that are allocated to users. TDMA divides each channel into time slots that are allocated to users. CDMA spreads the signal over a wide bandwidth using pseudo-random codes and allows multiple signals to overlap in both time and frequency.
Multiple access techniques
This document discusses multiple access techniques for wireless communication, including Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), and Code Division Multiple Access (CDMA). It describes the basic concepts of each technique, including how they divide up frequency bands, time slots, or codes to allow multiple users to access a shared radio channel simultaneously. The document also provides examples of cellular systems that use each type of multiple access technique, such as Advanced Mobile Phone System (AMPS) using FDMA/FDD and Global System for Mobile (GSM) using TDMA/FDD. It defines terms like frame efficiency that describe how effectively each technique utilizes available resources.
Multiple access techniques
Multiple access techniques allow multiple users to share the same wireless spectrum simultaneously. Common techniques include frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA). FDMA assigns each user a different frequency band. TDMA assigns each user time slots on the same frequency. CDMA spreads each user's signal across the entire frequency band using unique codes.
Imt 2000
3G cellular networks aimed to provide higher bandwidth and data rates, global roaming, and support for multimedia services. The ITU defined the IMT-2000 standard to enable these capabilities. Major 3G technologies included W-CDMA, CDMA2000, and UWC-136. Early 3G networks rolled out starting in 2001, with the Japanese and Koreans among the first to offer services meeting IMT-2000 specifications. Key technologies like higher bandwidths, packet switching, coherent modulation, smart antennas, and interference management helped 3G networks provide improved performance over 2G networks.
Spread Spectrum Multiple Access
Spread spectrum communication was first described in 1941 by actress Hedy Lamarr and pianist George Antheil in a patent for a secure radio link to control torpedoes. Spread spectrum works by transmitting signals across a wider bandwidth than the minimum needed using a code known by the transmitter and receiver. It provides benefits like immunity to interference and robust multiple access capability, though it is not bandwidth efficient for single users. Some examples of multiple access techniques that use spread spectrum are frequency hopping and direct sequence spread spectrum.
Recommended
2.3 time division multiple access
TDMA divides the radio spectrum into time slots and allows only one user to transmit or receive data during each time slot. It uses a buffer-and-burst transmission method, making it well-suited for digital systems. TDMA systems employ TDMA/TDD or TDMA/FDD for duplexing and multiple access. A TDMA frame includes a preamble for identification and synchronization, and multiple time slots containing user data, trail bits, and guard bits between slots. TDMA provides high transmission rates, simpler handoff, and is more cost-effective than FDMA, though it requires minimum guard times between slots to avoid interference.
2.6 cellular concepts - frequency reusing, channel assignment
- Cellular networks address the problem of limited spectrum availability by using frequency reuse, where nearby base stations are assigned different channels to avoid interference. Cells are arranged in a hexagonal pattern and the same set of channels are reused in cells sufficiently far from each other.
- There are two main channel assignment strategies - fixed assignment, where each cell has a predetermined set of channels, and dynamic assignment, where channels are allocated on demand by a central controller considering interference levels. Dynamic assignment helps improve spectrum utilization but requires more complex coordination.
- Frequency reuse allows the available spectrum to be reused as needed across multiple cells as long as interference is kept at acceptable levels, increasing network capacity.
2.4 code division multiple access
This document discusses different multiple access techniques used in wireless communication systems. It provides details about Code Division Multiple Access (CDMA) including: how CDMA uses pseudorandom codes and spreading signals to allow simultaneous transmission from multiple users; the need for orthogonal codes to minimize interference; and challenges like near-far problem when power levels differ between users. It also compares CDMA with Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA), listing pros and cons of CDMA, and how its capacity depends on interference level rather than bandwidth.
Chapter 7 multiple access techniques
Multiple access techniques allow multiple users to share finite radio spectrum resources simultaneously. They can be categorized as narrowband or wideband. Common techniques include FDMA, TDMA, CDMA, and SDMA. FDMA divides the total bandwidth into narrow channels that are allocated to users. TDMA divides each channel into time slots that are allocated to users. CDMA spreads the signal over a wide bandwidth using pseudo-random codes and allows multiple signals to overlap in both time and frequency.
Multiple access techniques
This document discusses multiple access techniques for wireless communication, including Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), and Code Division Multiple Access (CDMA). It describes the basic concepts of each technique, including how they divide up frequency bands, time slots, or codes to allow multiple users to access a shared radio channel simultaneously. The document also provides examples of cellular systems that use each type of multiple access technique, such as Advanced Mobile Phone System (AMPS) using FDMA/FDD and Global System for Mobile (GSM) using TDMA/FDD. It defines terms like frame efficiency that describe how effectively each technique utilizes available resources.
Multiple access techniques
Multiple access techniques allow multiple users to share the same wireless spectrum simultaneously. Common techniques include frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA). FDMA assigns each user a different frequency band. TDMA assigns each user time slots on the same frequency. CDMA spreads each user's signal across the entire frequency band using unique codes.
Imt 2000
3G cellular networks aimed to provide higher bandwidth and data rates, global roaming, and support for multimedia services. The ITU defined the IMT-2000 standard to enable these capabilities. Major 3G technologies included W-CDMA, CDMA2000, and UWC-136. Early 3G networks rolled out starting in 2001, with the Japanese and Koreans among the first to offer services meeting IMT-2000 specifications. Key technologies like higher bandwidths, packet switching, coherent modulation, smart antennas, and interference management helped 3G networks provide improved performance over 2G networks.
Spread Spectrum Multiple Access
Spread spectrum communication was first described in 1941 by actress Hedy Lamarr and pianist George Antheil in a patent for a secure radio link to control torpedoes. Spread spectrum works by transmitting signals across a wider bandwidth than the minimum needed using a code known by the transmitter and receiver. It provides benefits like immunity to interference and robust multiple access capability, though it is not bandwidth efficient for single users. Some examples of multiple access techniques that use spread spectrum are frequency hopping and direct sequence spread spectrum.
Frequency Division Multiple Access (FDMA)
Frequency Division Multiple Access (FDMA) is a channel access method where the available bandwidth is divided into multiple non-overlapping frequency bands and each user is assigned a specific frequency band. Each user can transmit or receive independently in its assigned frequency band without interference from other users. FDMA requires expensive bandpass filters for each frequency band and has strict linearity requirements for the transmission medium. The number of channels in an FDMA system is calculated by dividing the total available bandwidth minus the guard bands by the bandwidth of each individual channel.
Fading and Large Scale Fading
Large scale fading, also known as shadow fading, occurs when an obstacle blocks the signal between the transmitter and receiver, significantly reducing signal strength. It represents medium scale fluctuations in signal strength over distances of tens to hundreds of meters due to environmental factors like buildings, trees, and terrain. The key characteristics are that the measured signal power differs substantially between locations at the same distance from the transmitter, and the signal strength deviates from the average power when shadowing occurs due to obstacles in the transmission path.
TDMA
TDMA (Time Division Multiple Access) is a digital transmission technology that allows multiple users to share the same frequency channel by dividing the signal into different time slots. It allocates a single frequency channel for a short time and then switches to another channel, with the digital samples from a single transmitter occupying different time slots across several frequency bands simultaneously. The current TDMA standard for cellular divides each channel into six time slots, with each signal using two slots, providing three times the capacity of earlier analog cellular standards.
Multiple access techniques for wireless communication
This document discusses multiple access techniques for wireless communication. It begins with an introduction to how multiple access schemes allow efficient sharing of limited radio spectrum among multiple users. It then provides a brief history of wireless communication and pioneers. The document goes on to explain various multiple access techniques in detail including FDMA, TDMA, CDMA, SDMA, and CSMA. It describes their applications, advantages, and disadvantages. Forward and reverse link power control in CDMA is also summarized.
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This document discusses multiplexing and multiple access techniques used in communication networks. It describes multiplexing as transmitting multiple signals over a single medium, such as frequency division multiplexing (FDM) and time division multiplexing (TDM). Multiple access allows several stations to transmit simultaneously into the same network using techniques like frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA). FDMA divides the available bandwidth into frequency slots, TDMA divides transmission time into time slots, and CDMA assigns unique codes to signals.
Multiple access techniques for wireless communications
Subject: wireless mobile communication.
Topics covered : FDMA, TDMA , Spread Spectrum Multiple Access,Space Division Multiple Access,Capacity of Cellular systems
MIMO
1) The document introduces MIMO (multiple-input multiple-output) wireless communication systems and discusses their advantages over traditional SISO systems, including higher spectral efficiency and ability to benefit from multipath propagation.
2) It describes the MIMO channel model and derives the capacity of MIMO systems using singular value decomposition and water-filling principles. MIMO capacity is shown to increase approximately linearly with the number of antennas.
3) Cooperative communication techniques that enable single-antenna devices to achieve MIMO-like benefits are introduced, along with the concepts of cognitive radio networks and spectrum pooling.
2.2 frequency division multiple access
Frequency Division Multiple Access (FDMA) is a multiple access technique that assigns individual frequency bands or channels to each user. FDMA avoids interference by ensuring each user is allocated a unique frequency band. While FDMA allows multiple users to access the channel simultaneously and has low inter-symbol interference, it requires tight RF filtering to minimize adjacent channel interference and duplexers, increasing costs. Non-linear effects from power amplifiers can also cause intermodulation frequencies, interfering with adjacent channels. The capacity of an FDMA system is calculated based on the total spectrum allocation, guard band allocation, and channel bandwidth.
MIMO in 15 minutes
This document provides an overview of MIMO (Multiple Input Multiple Output) technology and its use in 802.11n wireless networks. MIMO works by using multiple antennas at both the transmitter and receiver to improve communication in three ways: by providing signal diversity to increase range and resilience, by enabling spatial multiplexing to increase data rates, and by allowing beamforming to focus signals in certain directions. The 802.11n standard will incorporate MIMO to achieve data rates up to 600Mbps using techniques like multi-path mitigation, modulation schemes, channel coding, and frame formatting adapted for MIMO transmissions. MIMO thus allows 802.11n to continue advancing wireless LAN speeds and performance.
Orthogonal frequency division multiplexing (ofdm)
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Frequency Reuse
This document discusses frequency reuse in cellular networks. It describes the frequency bands used in GSM900 and GSM1800 standards. Common frequency reuse patterns include "4 3", "3 3", and dual frequency reuse. Frequency reuse allows the same frequencies to be used in different cells by ensuring sufficient distance between those cells. The document also provides equations to calculate frequency reuse distance based on cell radius and reuse factor.
Mimo
This document discusses multiple-input multiple-output (MIMO) systems, including their motivations and capabilities. MIMO systems use multiple antennas at both the transmitter and receiver to achieve high data rates approaching 1 Gbps while maintaining quality of service. The document covers MIMO channel models and capacity, design criteria like diversity and spatial multiplexing, practical architectures like V-BLAST and Alamouti's scheme, and applications to networking including MIMO-OFDM and MIMO MAC protocols.
Spread spectrum
Spread spectrum communication uses wideband noise-like signals that are hard to detect, intercept, or jam. It spreads data over multiple frequencies. There are two main techniques: direct sequence spread spectrum multiplies a data signal by a pseudorandom code, and frequency hopping spread spectrum modulates a narrowband carrier that hops between frequencies. Spread spectrum provides benefits like resistance to interference and jamming, better signal quality, and inherent security. It finds applications in wireless networks, Bluetooth, and CDMA cellular systems.
GSM channels
Physical channels carry information over the air interface between the mobile station and base transceiver station. Logical channels map user data and signaling information onto physical channels. There are two main types of logical channels - traffic channels which carry call data, and control channels which communicate service information. Control channels include broadcast channels which transmit cell-wide information, common channels used for paging and access procedures, and dedicated channels for signaling during calls or when not on a call. Logical channels are mapped onto physical channels to effectively transmit information wirelessly between network components in a GSM system.
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This power point presentation discusses cell splitting and sectoring techniques used to increase channel capacity in cellular networks. It explains that a large cellular area is divided into smaller hexagonal cells, each with its own base station and frequency set. To further increase capacity, cells can be split into smaller cells served by additional base stations. Alternatively, directional antennas can be used to sector each cell into three segments to reduce interference and allow frequency reuse over smaller areas. Both techniques aim to add channels by subdividing congested cells.
Wavelength division multiplexing
This presentation is just a basic explanation of wavelength division multiplexing.
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Cdma ppt for ECE
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Ec 2401 wireless communication unit 5
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Multiplexing, fdma,tdma,cdma
The document discusses various multiplexing techniques including frequency division multiplexing (FDM), wavelength division multiplexing (WDM), time division multiplexing (TDM), and code division multiplexing (CDM). It provides examples of how each technique works, such as using different carrier frequencies for FDM, assigning time slots to each channel for TDM, and multiplying data values by unique code sequences for CDM. The techniques allow multiple signals to be combined and transmitted over a shared medium then separated again at the receiving end.
3.TDMA ACCESS TECHNOLOGY.pptx
This document discusses various multiple access techniques used in cellular communication systems. It describes Time Division Multiple Access (TDMA) which allows multiple users to share the same frequency channel by dividing the signal into different time slots. Frequency Division Multiple Access (FDMA) allocates different frequency bands to each user. Code Division Multiple Access (CDMA) separates users by assigning them different code channels. Space Division Multiple Access (SDMA) controls radiated energy for each user spatially using adaptive antennas. The document also discusses the efficiency, capacity and interference considerations of these different multiple access techniques.
schaeffner.ppt
1) Multiple techniques exist for wireless communication including FDMA, TDMA, CDMA, and SDMA which divide up the available spectrum by frequency, time, code, or space respectively.
2) TDMA and FDMA are examples of narrowband systems that utilize many narrow channels, while CDMA is a wideband technique allowing multiple transmitters to share a single radio channel simultaneously.
3) The capacity of cellular systems depends on factors like the carrier-to-interference ratio and minimum acceptable signal quality, with digital techniques allowing higher capacity due to improved ratios compared to analog.
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Frequency Division Multiple Access (FDMA)
Frequency Division Multiple Access (FDMA) is a channel access method where the available bandwidth is divided into multiple non-overlapping frequency bands and each user is assigned a specific frequency band. Each user can transmit or receive independently in its assigned frequency band without interference from other users. FDMA requires expensive bandpass filters for each frequency band and has strict linearity requirements for the transmission medium. The number of channels in an FDMA system is calculated by dividing the total available bandwidth minus the guard bands by the bandwidth of each individual channel.
Fading and Large Scale Fading
Large scale fading, also known as shadow fading, occurs when an obstacle blocks the signal between the transmitter and receiver, significantly reducing signal strength. It represents medium scale fluctuations in signal strength over distances of tens to hundreds of meters due to environmental factors like buildings, trees, and terrain. The key characteristics are that the measured signal power differs substantially between locations at the same distance from the transmitter, and the signal strength deviates from the average power when shadowing occurs due to obstacles in the transmission path.
TDMA
TDMA (Time Division Multiple Access) is a digital transmission technology that allows multiple users to share the same frequency channel by dividing the signal into different time slots. It allocates a single frequency channel for a short time and then switches to another channel, with the digital samples from a single transmitter occupying different time slots across several frequency bands simultaneously. The current TDMA standard for cellular divides each channel into six time slots, with each signal using two slots, providing three times the capacity of earlier analog cellular standards.
Multiple access techniques for wireless communication
This document discusses multiple access techniques for wireless communication. It begins with an introduction to how multiple access schemes allow efficient sharing of limited radio spectrum among multiple users. It then provides a brief history of wireless communication and pioneers. The document goes on to explain various multiple access techniques in detail including FDMA, TDMA, CDMA, SDMA, and CSMA. It describes their applications, advantages, and disadvantages. Forward and reverse link power control in CDMA is also summarized.
TDMA, FDMA, and CDMA
What are the differences between FDMA, CDMA and TDMA?
How they work?
Adv and DisAdv of them.
Real life applications etc
Satellite ppt
This document discusses multiplexing and multiple access techniques used in communication networks. It describes multiplexing as transmitting multiple signals over a single medium, such as frequency division multiplexing (FDM) and time division multiplexing (TDM). Multiple access allows several stations to transmit simultaneously into the same network using techniques like frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA). FDMA divides the available bandwidth into frequency slots, TDMA divides transmission time into time slots, and CDMA assigns unique codes to signals.
Multiple access techniques for wireless communications
Subject: wireless mobile communication.
Topics covered : FDMA, TDMA , Spread Spectrum Multiple Access,Space Division Multiple Access,Capacity of Cellular systems
MIMO
1) The document introduces MIMO (multiple-input multiple-output) wireless communication systems and discusses their advantages over traditional SISO systems, including higher spectral efficiency and ability to benefit from multipath propagation.
2) It describes the MIMO channel model and derives the capacity of MIMO systems using singular value decomposition and water-filling principles. MIMO capacity is shown to increase approximately linearly with the number of antennas.
3) Cooperative communication techniques that enable single-antenna devices to achieve MIMO-like benefits are introduced, along with the concepts of cognitive radio networks and spectrum pooling.
2.2 frequency division multiple access
Frequency Division Multiple Access (FDMA) is a multiple access technique that assigns individual frequency bands or channels to each user. FDMA avoids interference by ensuring each user is allocated a unique frequency band. While FDMA allows multiple users to access the channel simultaneously and has low inter-symbol interference, it requires tight RF filtering to minimize adjacent channel interference and duplexers, increasing costs. Non-linear effects from power amplifiers can also cause intermodulation frequencies, interfering with adjacent channels. The capacity of an FDMA system is calculated based on the total spectrum allocation, guard band allocation, and channel bandwidth.
MIMO in 15 minutes
This document provides an overview of MIMO (Multiple Input Multiple Output) technology and its use in 802.11n wireless networks. MIMO works by using multiple antennas at both the transmitter and receiver to improve communication in three ways: by providing signal diversity to increase range and resilience, by enabling spatial multiplexing to increase data rates, and by allowing beamforming to focus signals in certain directions. The 802.11n standard will incorporate MIMO to achieve data rates up to 600Mbps using techniques like multi-path mitigation, modulation schemes, channel coding, and frame formatting adapted for MIMO transmissions. MIMO thus allows 802.11n to continue advancing wireless LAN speeds and performance.
Orthogonal frequency division multiplexing (ofdm)
this ppt is focused on general information about OFDM, its types, advantages, disadvantages and applications
Frequency Reuse
This document discusses frequency reuse in cellular networks. It describes the frequency bands used in GSM900 and GSM1800 standards. Common frequency reuse patterns include "4 3", "3 3", and dual frequency reuse. Frequency reuse allows the same frequencies to be used in different cells by ensuring sufficient distance between those cells. The document also provides equations to calculate frequency reuse distance based on cell radius and reuse factor.
Mimo
This document discusses multiple-input multiple-output (MIMO) systems, including their motivations and capabilities. MIMO systems use multiple antennas at both the transmitter and receiver to achieve high data rates approaching 1 Gbps while maintaining quality of service. The document covers MIMO channel models and capacity, design criteria like diversity and spatial multiplexing, practical architectures like V-BLAST and Alamouti's scheme, and applications to networking including MIMO-OFDM and MIMO MAC protocols.
Spread spectrum
Spread spectrum communication uses wideband noise-like signals that are hard to detect, intercept, or jam. It spreads data over multiple frequencies. There are two main techniques: direct sequence spread spectrum multiplies a data signal by a pseudorandom code, and frequency hopping spread spectrum modulates a narrowband carrier that hops between frequencies. Spread spectrum provides benefits like resistance to interference and jamming, better signal quality, and inherent security. It finds applications in wireless networks, Bluetooth, and CDMA cellular systems.
GSM channels
Physical channels carry information over the air interface between the mobile station and base transceiver station. Logical channels map user data and signaling information onto physical channels. There are two main types of logical channels - traffic channels which carry call data, and control channels which communicate service information. Control channels include broadcast channels which transmit cell-wide information, common channels used for paging and access procedures, and dedicated channels for signaling during calls or when not on a call. Logical channels are mapped onto physical channels to effectively transmit information wirelessly between network components in a GSM system.
cell splitting and sectoring
This power point presentation discusses cell splitting and sectoring techniques used to increase channel capacity in cellular networks. It explains that a large cellular area is divided into smaller hexagonal cells, each with its own base station and frequency set. To further increase capacity, cells can be split into smaller cells served by additional base stations. Alternatively, directional antennas can be used to sector each cell into three segments to reduce interference and allow frequency reuse over smaller areas. Both techniques aim to add channels by subdividing congested cells.
Wavelength division multiplexing
This presentation is just a basic explanation of wavelength division multiplexing.
Hope this is useful. :)
Cdma ppt for ECE
CDMA is a digital cellular technology that allows multiple users to access a single radio channel simultaneously through the use of unique code assignments. The document discusses CDMA network architecture, which includes mobile stations, base stations, base station controllers, mobile switching centers, home and visitor location registers, and authentication centers. It also compares CDMA to earlier multiple access technologies like TDMA and FDMA, noting advantages of CDMA like increased capacity and soft handoffs between cells using the same frequency.
Ec 2401 wireless communication unit 5
The document discusses advanced transceiver schemes including spread spectrum systems, code division multiple access (CDMA), orthogonal frequency division multiplexing (OFDM), and wireless network standards. It provides details on direct sequence spread spectrum, frequency hopping spread spectrum, CDMA principles and power control, OFDM principles and implementation, and 2G and 3G wireless network standards including GSM.
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The document discusses various multiplexing techniques including frequency division multiplexing (FDM), wavelength division multiplexing (WDM), time division multiplexing (TDM), and code division multiplexing (CDM). It provides examples of how each technique works, such as using different carrier frequencies for FDM, assigning time slots to each channel for TDM, and multiplying data values by unique code sequences for CDM. The techniques allow multiple signals to be combined and transmitted over a shared medium then separated again at the receiving end.
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Similar to multiple access for wireless mobile communications
3.TDMA ACCESS TECHNOLOGY.pptx
This document discusses various multiple access techniques used in cellular communication systems. It describes Time Division Multiple Access (TDMA) which allows multiple users to share the same frequency channel by dividing the signal into different time slots. Frequency Division Multiple Access (FDMA) allocates different frequency bands to each user. Code Division Multiple Access (CDMA) separates users by assigning them different code channels. Space Division Multiple Access (SDMA) controls radiated energy for each user spatially using adaptive antennas. The document also discusses the efficiency, capacity and interference considerations of these different multiple access techniques.
schaeffner.ppt
1) Multiple techniques exist for wireless communication including FDMA, TDMA, CDMA, and SDMA which divide up the available spectrum by frequency, time, code, or space respectively.
2) TDMA and FDMA are examples of narrowband systems that utilize many narrow channels, while CDMA is a wideband technique allowing multiple transmitters to share a single radio channel simultaneously.
3) The capacity of cellular systems depends on factors like the carrier-to-interference ratio and minimum acceptable signal quality, with digital techniques allowing higher capacity due to improved ratios compared to analog.
Ea 452 chap9
The document summarizes the evolution of multiple access techniques used in mobile communications systems over time. Early systems used simplex or half duplex frequency modulation. Cellular concepts and frequency division duplexing were developed in the 1950s-1960s. The first US cellular system was AMPS in 1983, using FDMA. Later, digital cellular and CDMA were introduced, using time division multiple access and code division multiple access respectively. Multiple access techniques allow sharing of bandwidth among users and include FDMA, TDMA, CDMA and their variations.
Multiplexing and Multiple access
This document provides a course syllabus on mobile and wireless communications. The syllabus covers 4 units:
1) Wireless transmission fundamentals like frequencies, signals, and propagation effects
2) Multiplexing techniques including FDM, TDM, CDMA, and modulation methods
3) Access control mechanisms like FDMA, TDMA, CDMA and their performance
4) Wireless networks including satellite, WLAN, WATM networks and protocols
It also lists recommended textbooks for the course.
satellite communication- UNIT-III.pptx
satellite communication jntuh
Satellite Link Design: Basic Transmission Theory, System Noise Temperature, and G/T Ratio,
Design of Down Links, Up Link Design, Design Of Satellite Links For Specified C/N, System Design
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Time Division Multiple Access (TDMA), Frame Structure, Examples, Satellite Switched TDMA
Onboard Processing, DAMA, Code Division Multiple Access (CDMA), Spread Spectrum Transmission
and Reception.
Multiple Access
This document discusses several multiple access techniques used in satellite communications, including Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Demand Access Multiple Access (DAMA), and Code Division Multiple Access (CDMA). FDMA divides the available frequency band into non-overlapping channels. TDMA allows multiple earth stations to share a transponder by taking turns transmitting bursts of signals. DAMA allocates satellite channels to users on demand. CDMA encodes signals so that a receiving station can recover information from an individual transmitter using the correct code.
L4 multiplexing & multiple access 16
This document discusses various techniques for multiplexing in wireless networks. It covers four main types of multiplexing: frequency-division multiplexing (FDM), time-division multiplexing (TDM), code-division multiplexing (CDM), and space-division multiplexing (SDM). For each technique, it provides examples of how they work, their advantages and disadvantages, and applications where they are used including GSM networks which combine FDM and TDM. It also discusses concepts like correlation between codes and how orthogonal codes allow receivers in CDMA networks to distinguish different user signals.
lec.2 Multiple Access.pptx
The document discusses multiple access technologies used in cellular networks, including Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA). FDMA divides the available spectrum into separate frequency channels that are assigned to users. TDMA divides each frequency channel into time slots that are assigned to users in a timed sequence. The document then covers the cellular concept, which involves dividing a service area into smaller cells served by low-power base stations and reusing frequencies in cells separated by a sufficient distance to avoid interference. This allows for increased network capacity compared to a single high-power transmitter covering the whole area. Key aspects covered include frequency reuse, cell shapes and sizes, interference types, and formulas for calculating reuse distance and network capacity
lec.2 Multiple Access.pptx
The document discusses multiple access technologies used in cellular networks, including Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA). FDMA divides the available spectrum into separate frequency channels that are assigned to users. TDMA divides each frequency channel into time slots that are assigned to users in a timed sequence. The document then covers the cellular concept, which involves dividing a service area into smaller cells served by low-power base stations and reusing frequencies in cells separated by a sufficient distance to avoid interference. This allows for increased network capacity compared to a single high-power transmitter covering the whole area. Key aspects covered include frequency reuse, cell shapes and sizes, interference types, and formulas for calculating reuse distance and network capacity
Mimo [new]
Multiple Input Multiple Output (MIMO) technology uses multiple antennas at both the transmitter and receiver to improve channel robustness and throughput. By utilizing reflected signals, MIMO can provide gains in channel robustness and throughput. MIMO was initially developed in the 1990s after additional processing power made it possible to utilize both spatial diversity and spatial multiplexing. MIMO systems provide either spatial multiplexing gain to maximize transmission rate or diversity gain to minimize errors and prioritize reliability. MIMO is now used in many wireless communication standards and ongoing research aims to develop more advanced MIMO techniques.
Multiple acces techniques
Multiple access techniques allow multiple mobile users to simultaneously share a finite amount of radio spectrum for communication. Common techniques include FDMA, TDMA, CDMA, and SDMA. FDMA allocates different frequency bands to different users. TDMA divides the available bandwidth into time slots that are allocated to users. CDMA spreads user signals over the entire available bandwidth through coding.
04_20.pptx
1) FDMA divides the total available bandwidth into narrow frequency bands, allocating each user an individual band, allowing simultaneous transmission without interference. TDMA divides each frequency channel into time slots, allocating slots to different users to share the channel.
2) TDMA offers advantages like increased efficiency, ability to transmit data and voice, and cost-effectiveness for upgrading analog to digital. Disadvantages include predefined time slots and multipath distortion.
3) FDMA is simpler but requires expensive filters, while TDMA uses cheaper logic but has problems from propagation delays and assigning time slots when roaming.
Multiplexing and spreading
This document discusses multiplexing and spreading techniques. It explains that multiplexing combines multiple analog or digital signals into one signal over a shared medium to efficiently use scarce resources. The main multiplexing techniques covered are frequency-division multiplexing (FDM), time-division multiplexing (TDM), wavelength-division multiplexing (WDM), and code-division multiple access (CDMA). It also discusses spread spectrum techniques like frequency hopping spread spectrum (FHSS) and direct sequence spread spectrum (DSSS) that spread signals across bandwidths.
25143515-Wireless-Communication.ppt
Cordless systems and wireless local loop (WLL) technologies provide wireless connectivity for voice and data services. Cordless systems operate in residential and office environments using base stations to connect to wired networks. WLL uses point-to-multipoint architectures with stationary antennas to deliver broadband connectivity over longer ranges than cordless systems. Standards like 802.16 specify the protocol architecture and frame formats for WLL, including physical layer modulation and medium access control. Considerations for WLL deployment include propagation effects at high frequencies and mitigating rain attenuation through frequency selection.
Frequency Division Multiplexing Access (FDMA)
Frequency Division Multiplexing Access (FDMA)
Multiple Access : Introduction
Multiplexing : Features
Multiplexing : Example
Multiplexing : Channelization
Multiplexing : Channelization Diagram
Frequency division multiple access(FDMA)
FDMA : Features
FDMA : Diagram
FDMA : Guard Bands
Guard Bands & Channel Assignment
FDMA : Capacity of System
FDMA : Advantages
FDMA : Disadvantages
FDMA : Uses
FDMA vs. TDMA
Pulse Shaping FIR Filter for WCDMA
This document analyzes the simulation parameters of a pulse shaping FIR filter for WCDMA. It simulates a square root raised cosine pulse shaping filter in MATLAB Simulink with varying group delay parameters. The simulation measures the number of bits, number of errors, and bit error rate at different group delays. It finds that the bit error rate is minimized at a group delay of 6 symbol periods. The optimal values found are a group delay of 6 and a roll off factor of 0.22.
Code Division Multiple Access- CDMA
CDMA is a digital cellular standard that allows multiple users to access the same radio frequency channel simultaneously through the use of unique code sequences. Users are separated by spreading their transmitted signals across the frequency band using pseudo-random codes. CDMA provides advantages over other multiple access techniques like FDMA and TDMA such as increased capacity, soft handoffs between cells, and covert operation due to its noise-like signals. The IS-95 standard introduced CDMA to cellular networks and specified the use of orthogonal codes to separate signals and a 1.25 MHz channel bandwidth to support multiple simultaneous voice calls.
2.5 capacity calculations of fdma, tdma and cdma
The document discusses the capacity calculations of cellular systems using FDMA, TDMA, and CDMA. For FDMA systems, capacity is limited by co-channel interference and calculated based on channel bandwidth, frequency reuse factor, and signal-to-interference ratio. TDMA systems improve capacity over analog systems through techniques like timeslot allocation and adaptive channel assignment. CDMA systems can reuse the entire spectrum in all cells, and capacity is interference-limited rather than bandwidth-limited. Capacity is increased in CDMA through sectorization, monitoring voice activity, and controlling transmit power.
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The document provides an overview of the GSM cellular network and its operations. It describes the main components including the mobile switching center (MSC), home location register (HLR), visitor location register (VLR), and authentication center (AUC). It also discusses the mobile handset, radio interface, network architecture, and how capacity is increased through frequency reuse, cell splitting, and sectoring.
Gsm1368
The document provides an overview of the key components and operations of a GSM cellular network. It describes the network and switching subsystem (NSS) which controls connections, mobility management, and interconnection. The NSS includes components like the Mobile Switching Center (MSC) and databases like the Home Location Register (HLR) and Visitor Location Register (VLR). It also describes the mobile handset, radio interface using TDMA, network architecture with cells, and methods to increase network capacity like frequency reuse, cell splitting, and sectoring.
Similar to multiple access for wireless mobile communications (20)
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SPREAD SPECTRUM
The document discusses spread spectrum techniques used to prevent eavesdropping and jamming by adding redundancy. It describes two types of spread spectrum: Frequency Hopping Spread Spectrum (FHSS) which spreads signals across the frequency domain, and Direct Sequence Spread Spectrum (DSSS) which spreads signals across the time domain. The document then compares FHSS and DSSS in terms of performance, issues, acceptance and applications.
Modulation Techniques for Mobile Radio
Modulation is the process of encoding information from a message source for transmission. It involves translating a baseband message signal to a bandpass signal at higher frequencies. Modulation can be done by varying the amplitude, phase, or frequency of a carrier signal based on the message signal. Digital modulation uses a discrete time sequence of symbols to represent bits of information, allowing for robustness and enabling techniques like error correction coding. The choice of digital modulation influences factors like bit error rate, power efficiency, bandwidth occupancy, and performance in fading channels.
Spread spectrum modulation
This document provides an overview of spread spectrum technologies including frequency hopping spread spectrum (FHSS) and direct sequence spread spectrum (DSSS). It defines spread spectrum, describes how data is modulated at different rates using DSSS, explains FHSS and DSSS in detail, and lists factors that impact wireless signal performance. Key aspects covered include the FCC regulations for unlicensed use of spread spectrum in the 2.4GHz band, how DSSS spreads and encodes data across multiple frequencies, and how FHSS rapidly hops between frequencies to transmit information.
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This document discusses different radio propagation models for both indoor and outdoor environments. It provides examples of common outdoor propagation models including the Longley-Rice model and Hata model. It also discusses indoor propagation models and key factors that influence indoor radio signals, such as building layout and construction materials. Common indoor path loss models include the log-distance path loss model and ITU indoor attenuation model. Radio propagation is influenced by factors like distance, environment, and signal penetration through buildings.
Mobile Radio Propagations
Mobile radio propagation models are derived using empirical and analytical methods to account for all known and unknown propagation factors. Signal strength must be strong enough for quality but not too strong to cause interference. Fading can disrupt signals and cause errors. Path loss models predict received signal level as a function of distance and are used to estimate signal-to-noise ratio. Path loss includes propagation, absorption, diffraction, and other losses. Large-scale models describe mean path loss over hundreds of meters while small-scale models characterize rapid fluctuations over small distances.
Propagation mechanisms
There are 3 main propagation mechanisms in mobile communication systems:
1. Reflection occurs when signals bounce off surfaces like buildings and earth.
2. Diffraction is when signals bend around obstacles like hills and buildings.
3. Scattering is when signals are deflected in many directions by small obstacles like trees and signs. These 3 mechanisms impact the received power and must be considered in propagation models.
Wlan
Wireless LANs can be used for LAN extension between buildings, nomadic access for mobile users, and temporary ad hoc networks. There are several wireless LAN categories including infrared, spread spectrum, and narrowband microwave networks. Infrared networks have an unlimited radio spectrum but are limited by concerns of eye safety and range. Spread spectrum networks use multiple-cell configurations with either peer-to-peer or hub-based topologies. Narrowband microwave networks can be licensed to avoid interference or use unlicensed spectrum at low power over short ranges.
Wifi wimax
WiFi uses radio frequencies in the 2.4GHz and 5GHz bands to enable wireless networking. It uses protocols like 802.11b, 802.11a, and 802.11g which define operating frequencies and data transmission rates. These protocols use techniques like spread spectrum and CSMA/CA to allow multiple devices to share the wireless spectrum and avoid interference between connections. Newer standards like 802.11n and WiMax promise higher speeds but come with increased complexity and costs.
2g 3g
1) Wireless communication technologies have evolved from 1G analog cellular to 4G broadband cellular networks, with each generation providing improved data capabilities.
2) Future wireless networks are moving to an all-IP architecture using a combination of technologies like WiFi, WWAN, and WLAN to provide higher speeds and capacity.
3) Key drivers for beyond 4G networks include meeting increasing demand for multimedia services, improving spectrum efficiency, and supporting data rates of 100Mbps for outdoor use and 1Gbps for indoor use.
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multiple access for wireless mobile communications
- 1. MULTIPLE ACCESS TECHNIQUES FOR WIRELESS COMMUNICATIONS UNIT - IV
- 9. Multiple Access Techniques in use Multiple Access Technique Advanced Mobile Phone System (AMPS) FDMA/FDD Global System for Mobile (GSM) TDMA/FDD US Digital Cellular (USDC) TDMA/FDD Digital European Cordless Telephone (DECT) FDMA/TDD US Narrowband Spread Spectrum (IS-95) CDMA/FDD Cellular System
- 19. Repeating Frame Structure Slot 1 Slot 2 Slot 3 … Slot N Preamble Information Message Trail Bits One TDMA Frame Trail Bits Sync. Bits Information Data Guard Bits The frame is cyclically repeated over time.
- 24. Repeating Frame Structure Slot 1 Slot 2 Slot 3 … Slot N Preamble Information Message Trail Bits One TDMA Frame Trail Bits Sync. Bits Information Data Guard Bits The frame is cyclically repeated over time.
- 34. Spread Spectrum
- 35. Frequency Hoping Spread Spectrum
- 36. Frequency Hopping Spread Spectrum
- 41. CDMA for Direct Sequence Spread Spectrum
- 42. CDMA Example
- 45. CAPACITY of CELLULAR SYSTEMS .
- 68. Capacity of SDMA systems
- 74. Capacity of SDMA systems