TDMA technology allows multiple users to access a single channel by dividing it into time slots. This increases spectral efficiency and channel capacity compared to analog systems. TDMA can integrate voice and data and provides better voice quality over greater ranges than analog. The document discusses how TDMA enables professional organizations to double their channel capacity to achieve 6.25 kHz efficiency, which will likely be a future regulatory requirement. It argues that two-slot 12.5 kHz TDMA is the best choice for professional mobile users due to its advantages in features, costs, battery life, and ability to further increase efficiency without interference.
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.
FDMA (frequency division multiple access) is a technology that divides the frequency band allocated for wireless communication into multiple channels, with each channel assigned to a single user. It allows more than one user to share the radio frequency spectrum by allocating different frequency channels. In FDMA, each call is placed on a separate frequency channel. It separates the spectrum into uniform chunks of bandwidth for voice channels. While capable of digital transmission, FDMA is not efficient for digital transmission.
This presentation based on TDMA technology,How it works,comparison between TDMA,FDMA,CDMA,Advantages and disadvantages of TDMA,Synchronization of TDMA and Evolution of TDMA
multiple access techniques used in wireless communicationSajid ali
This document discusses multiple access techniques for wireless communication. It describes frequency division duplexing (FDD) and time division duplexing (TDD) for sharing radio spectrum. The main multiple access techniques are described as frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA). FDMA allocates different frequency bands to each user, TDMA divides the available time into time slots and allocates one slot per user, and CDMA uses pseudo-random codes to distinguish users transmitting simultaneously on the same frequency. Common cellular systems like AMPS, GSM, and IS-95 are cited as examples.
Multiple access techniques for wireless communicationDr.Umadevi V
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 allows multiple users to share the same frequency channel by dividing the signal into different time slots. Each user transmits in brief bursts at periodic intervals, with the time slots being allocated so as not to interfere with each other. Key advantages include efficient use of spectrum and ability to carry voice and data. TDMA networks provide approximately three times the voice channel capacity of analog networks.
This document discusses multiple access techniques for wireless communications, including FDMA, TDMA, and CDMA. It provides details on how each technique works and its advantages and disadvantages. FDMA divides the frequency band into channels that can be assigned to individual users. TDMA divides each channel into time slots that can be assigned to users. CDMA allows all users to use the whole available bandwidth simultaneously by using unique codes to distinguish users' signals.
multiple access techniques for wireless communicationSajid ali
This document discusses multiple access techniques for wireless communication. It describes three main techniques: frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA). FDMA allocates different frequency bands to different users. TDMA divides the available bandwidth into time slots and allocates slots to users. CDMA spreads user signals using unique codes and allows simultaneous transmission. Common cellular systems that use these techniques include AMPS (FDMA), GSM (TDMA), and IS-95 (CDMA).
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.
FDMA (frequency division multiple access) is a technology that divides the frequency band allocated for wireless communication into multiple channels, with each channel assigned to a single user. It allows more than one user to share the radio frequency spectrum by allocating different frequency channels. In FDMA, each call is placed on a separate frequency channel. It separates the spectrum into uniform chunks of bandwidth for voice channels. While capable of digital transmission, FDMA is not efficient for digital transmission.
This presentation based on TDMA technology,How it works,comparison between TDMA,FDMA,CDMA,Advantages and disadvantages of TDMA,Synchronization of TDMA and Evolution of TDMA
multiple access techniques used in wireless communicationSajid ali
This document discusses multiple access techniques for wireless communication. It describes frequency division duplexing (FDD) and time division duplexing (TDD) for sharing radio spectrum. The main multiple access techniques are described as frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA). FDMA allocates different frequency bands to each user, TDMA divides the available time into time slots and allocates one slot per user, and CDMA uses pseudo-random codes to distinguish users transmitting simultaneously on the same frequency. Common cellular systems like AMPS, GSM, and IS-95 are cited as examples.
Multiple access techniques for wireless communicationDr.Umadevi V
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 allows multiple users to share the same frequency channel by dividing the signal into different time slots. Each user transmits in brief bursts at periodic intervals, with the time slots being allocated so as not to interfere with each other. Key advantages include efficient use of spectrum and ability to carry voice and data. TDMA networks provide approximately three times the voice channel capacity of analog networks.
This document discusses multiple access techniques for wireless communications, including FDMA, TDMA, and CDMA. It provides details on how each technique works and its advantages and disadvantages. FDMA divides the frequency band into channels that can be assigned to individual users. TDMA divides each channel into time slots that can be assigned to users. CDMA allows all users to use the whole available bandwidth simultaneously by using unique codes to distinguish users' signals.
multiple access techniques for wireless communicationSajid ali
This document discusses multiple access techniques for wireless communication. It describes three main techniques: frequency division multiple access (FDMA), time division multiple access (TDMA), and code division multiple access (CDMA). FDMA allocates different frequency bands to different users. TDMA divides the available bandwidth into time slots and allocates slots to users. CDMA spreads user signals using unique codes and allows simultaneous transmission. Common cellular systems that use these techniques include AMPS (FDMA), GSM (TDMA), and IS-95 (CDMA).
Code Division Multiple Access (CDMA) is a spread spectrum multiple access technique that allows multiple users to access the same bandwidth simultaneously. It uses pseudorandom code sequences to spread the signal over a wide bandwidth. The two main types of SSMA are Frequency Hopped Multiple Access (FHMA) and Direct Sequence Multiple Access (DSMA), with DSMA also known as CDMA. In CDMA, each user is assigned a unique code and the receiver uses correlation to separate the signals. Power control is needed to address the near-far problem where stronger signals can drown out weaker ones. Features of CDMA include soft capacity limits, resistance to multipath fading, and soft handoffs between cells without switching frequencies.
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.
This document discusses multiple access communication techniques. It introduces frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and space/beam division multiple access (SDMA). FDMA assigns each user a pair of frequencies, TDMA divides bandwidth into time slots and assigns users slots, CDMA allows signals to occupy the same channel using unique codes, and SDMA serves different users using concentrated spot beams. The document provides examples of applications and advantages/disadvantages of each technique.
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 IN WIRELESS COMMUNICATIONjuhi kumari
Multiple access techniques allow multiple terminals to share access to a transmission medium. The document discusses several techniques: frequency division multiple access (FDMA) allocates different frequencies to different users; time division multiple access (TDMA) divides the time frame into slots and allocates different time slots to different users; code division multiple access (CDMA) allocates different codes to different users; space division multiple access (SDMA) uses directional antennas to spatially separate users. The document also discusses ALOHA, slotted ALOHA, carrier sense multiple access (CSMA), and multiple access collision avoidance (MACA) protocols for wireless networks.
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.
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.
The document discusses multiplexing and multiple access techniques. It describes frequency division multiplexing (FDM), time division multiplexing (TDM), code division multiplexing (CDM), and code division multiple access (CDMA). FDM separates a shared transmission medium into different frequency channels. TDM allows multiple signals to share the same transmission medium by dividing the signal into different time slots. CDM uses unique codes to distinguish between signals transmitted over the same shared band. CDMA is a multiple access scheme that uses spread spectrum technology and pseudo-random codes.
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.
This document summarizes key aspects of cellular telephony systems and the CDMA technique. It begins by outlining cellular telephony and multiple access techniques like TDMA, FDMA, and CDMA. It then focuses on CDMA, explaining that it uses spread spectrum techniques to allow multiple users to share frequencies simultaneously through encoding with pseudo-random digital sequences. The document outlines the spread spectrum technique used in CDMA and how it transmits and reconstructs data. It concludes by listing advantages of CDMA like high spectral capacity and call quality, and disadvantages such as limitations in international roaming and degradation of audio quality with large numbers of users.
Presentation on MULTIPLE ACCESS TECHNIQUES FOR WIRELESS COMMUNICATION By SUPRIYA BHARATI (ME/EC/10006/16) and KHUSHBOO KUMARI (ME/EC/10010/16) Under the Guidance of Dr. Sanjay Kumar Department of Electronics & Communication Engg. (ECE) Birla Institute of Technology, Mesra ,Ranchi-835215 , Jharkhand , India
The document provides background information on various wireless technologies including LTE, UMB, and WiMax. It discusses their origins, standards development organizations, key enhancements over time, and speed capabilities. For example, it explains that LTE evolved from GSM/UMTS standards through 3GPP, while UMB originated from CDMA2000/EVDO standards and WiMax came from IEEE 802.16 standards for wireless metropolitan area networks. It provides timelines of developments and comparisons of download/upload speeds for different generations of each technology.
you can be friend with me on orkut
"mangalforyou@gmail.com" : i belive in sharing the knowledge so please send project reports ,seminar and ppt. to me .
This document discusses space division multiplexing (SDM), a new technique for fiber optic communication that increases transmission capacity. SDM utilizes unused space within the core or additional fiber cores to establish independent transmission channels. There are two main SDM strategies: multi-core fiber which has multiple cores embedded in the cladding, and multi-mode fiber which supports propagation of multiple independent modes within a single core. SDM provides significant advantages like high scalability and the ability to achieve terabit per second throughput. When combined with software defined networking, SDM networks also enable efficient infrastructure utilization and flexible bandwidth provisioning. However, SDM also faces challenges like crosstalk between cores and high insertion losses.
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.
CDMA (Code Division Multiple Access) is a channel access method used in radio communication that allows multiple users to transmit simultaneously over the same frequency by assigning each user a unique code. It employs spread spectrum technology and coding to multiplex multiple signals over one physical channel. CDMA differs from TDMA, which divides access by time, and FDMA, which divides it by frequency. CDMA spreads the modulated coded signal over a wider bandwidth than the original data. It is analogous to people speaking different languages to avoid confusion over the same communication channel.
This document discusses multiplexing techniques used in mobile computing. It describes four types of multiplexing: frequency division multiplexing (FDM), time division multiplexing (TDM), code division multiplexing (CDM), and space division multiplexing (SDM). For each type, it provides details on how the technique works and its advantages and disadvantages. FDM uses different frequencies to transmit multiple signals simultaneously. TDM divides a signal into time slots to share a frequency. CDM assigns unique codes to signals sharing the same frequency. SDM splits a channel across physical locations.
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.
TDMA (Time Division Multiple Access) is a digital wireless telephone transmission technique that allocates the given bandwidth to different users in different time slots. Each user is only allowed to transmit within their specified time interval. A TDMA frame structure divides each frequency channel into a series of time slots that are assigned to individual users. The advantages of TDMA include allowing a single channel to be used by multiple users, reducing the need for radio transceivers and allowing for smaller cell sizes. However, TDMA requires accurate clocks to avoid time jittering and multipath distortion.
Frequency division multiplexing (FDM) divides the available bandwidth into non-overlapping frequency bands, with each band carrying a separate signal. Time division multiplexing (TDM) divides signals into different time slots to share the same frequency channel. TDM samples voice frequency signals at 8 kHz and quantizes each sample to 8 bits, requiring 64 kbps per voice channel. A 32-channel PCM system using TDM requires 2 Mbps of bandwidth and can carry more voice channels than FDM with the same bandwidth.
This document summarizes different types of multiplexing techniques used in communication systems:
1) Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), Wavelength Division Multiplexing (WDM), and Code Division Multiple Access (CDMA). FDM separates users by allocating different frequency bands, TDM separates users by assigning different time slots, WDM separates signals using different wavelengths of light, and CDMA separates users by encoding data with unique spreading codes.
2) TDM uses a commutator to sample multiple signals and transmit them serially, with each user getting a time slot. TDMA divides a time frame into slots and assigns each user a slot.
3) W
Code Division Multiple Access (CDMA) is a spread spectrum multiple access technique that allows multiple users to access the same bandwidth simultaneously. It uses pseudorandom code sequences to spread the signal over a wide bandwidth. The two main types of SSMA are Frequency Hopped Multiple Access (FHMA) and Direct Sequence Multiple Access (DSMA), with DSMA also known as CDMA. In CDMA, each user is assigned a unique code and the receiver uses correlation to separate the signals. Power control is needed to address the near-far problem where stronger signals can drown out weaker ones. Features of CDMA include soft capacity limits, resistance to multipath fading, and soft handoffs between cells without switching frequencies.
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.
This document discusses multiple access communication techniques. It introduces frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and space/beam division multiple access (SDMA). FDMA assigns each user a pair of frequencies, TDMA divides bandwidth into time slots and assigns users slots, CDMA allows signals to occupy the same channel using unique codes, and SDMA serves different users using concentrated spot beams. The document provides examples of applications and advantages/disadvantages of each technique.
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 IN WIRELESS COMMUNICATIONjuhi kumari
Multiple access techniques allow multiple terminals to share access to a transmission medium. The document discusses several techniques: frequency division multiple access (FDMA) allocates different frequencies to different users; time division multiple access (TDMA) divides the time frame into slots and allocates different time slots to different users; code division multiple access (CDMA) allocates different codes to different users; space division multiple access (SDMA) uses directional antennas to spatially separate users. The document also discusses ALOHA, slotted ALOHA, carrier sense multiple access (CSMA), and multiple access collision avoidance (MACA) protocols for wireless networks.
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.
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.
The document discusses multiplexing and multiple access techniques. It describes frequency division multiplexing (FDM), time division multiplexing (TDM), code division multiplexing (CDM), and code division multiple access (CDMA). FDM separates a shared transmission medium into different frequency channels. TDM allows multiple signals to share the same transmission medium by dividing the signal into different time slots. CDM uses unique codes to distinguish between signals transmitted over the same shared band. CDMA is a multiple access scheme that uses spread spectrum technology and pseudo-random codes.
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.
This document summarizes key aspects of cellular telephony systems and the CDMA technique. It begins by outlining cellular telephony and multiple access techniques like TDMA, FDMA, and CDMA. It then focuses on CDMA, explaining that it uses spread spectrum techniques to allow multiple users to share frequencies simultaneously through encoding with pseudo-random digital sequences. The document outlines the spread spectrum technique used in CDMA and how it transmits and reconstructs data. It concludes by listing advantages of CDMA like high spectral capacity and call quality, and disadvantages such as limitations in international roaming and degradation of audio quality with large numbers of users.
Presentation on MULTIPLE ACCESS TECHNIQUES FOR WIRELESS COMMUNICATION By SUPRIYA BHARATI (ME/EC/10006/16) and KHUSHBOO KUMARI (ME/EC/10010/16) Under the Guidance of Dr. Sanjay Kumar Department of Electronics & Communication Engg. (ECE) Birla Institute of Technology, Mesra ,Ranchi-835215 , Jharkhand , India
The document provides background information on various wireless technologies including LTE, UMB, and WiMax. It discusses their origins, standards development organizations, key enhancements over time, and speed capabilities. For example, it explains that LTE evolved from GSM/UMTS standards through 3GPP, while UMB originated from CDMA2000/EVDO standards and WiMax came from IEEE 802.16 standards for wireless metropolitan area networks. It provides timelines of developments and comparisons of download/upload speeds for different generations of each technology.
you can be friend with me on orkut
"mangalforyou@gmail.com" : i belive in sharing the knowledge so please send project reports ,seminar and ppt. to me .
This document discusses space division multiplexing (SDM), a new technique for fiber optic communication that increases transmission capacity. SDM utilizes unused space within the core or additional fiber cores to establish independent transmission channels. There are two main SDM strategies: multi-core fiber which has multiple cores embedded in the cladding, and multi-mode fiber which supports propagation of multiple independent modes within a single core. SDM provides significant advantages like high scalability and the ability to achieve terabit per second throughput. When combined with software defined networking, SDM networks also enable efficient infrastructure utilization and flexible bandwidth provisioning. However, SDM also faces challenges like crosstalk between cores and high insertion losses.
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.
CDMA (Code Division Multiple Access) is a channel access method used in radio communication that allows multiple users to transmit simultaneously over the same frequency by assigning each user a unique code. It employs spread spectrum technology and coding to multiplex multiple signals over one physical channel. CDMA differs from TDMA, which divides access by time, and FDMA, which divides it by frequency. CDMA spreads the modulated coded signal over a wider bandwidth than the original data. It is analogous to people speaking different languages to avoid confusion over the same communication channel.
This document discusses multiplexing techniques used in mobile computing. It describes four types of multiplexing: frequency division multiplexing (FDM), time division multiplexing (TDM), code division multiplexing (CDM), and space division multiplexing (SDM). For each type, it provides details on how the technique works and its advantages and disadvantages. FDM uses different frequencies to transmit multiple signals simultaneously. TDM divides a signal into time slots to share a frequency. CDM assigns unique codes to signals sharing the same frequency. SDM splits a channel across physical locations.
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.
TDMA (Time Division Multiple Access) is a digital wireless telephone transmission technique that allocates the given bandwidth to different users in different time slots. Each user is only allowed to transmit within their specified time interval. A TDMA frame structure divides each frequency channel into a series of time slots that are assigned to individual users. The advantages of TDMA include allowing a single channel to be used by multiple users, reducing the need for radio transceivers and allowing for smaller cell sizes. However, TDMA requires accurate clocks to avoid time jittering and multipath distortion.
Frequency division multiplexing (FDM) divides the available bandwidth into non-overlapping frequency bands, with each band carrying a separate signal. Time division multiplexing (TDM) divides signals into different time slots to share the same frequency channel. TDM samples voice frequency signals at 8 kHz and quantizes each sample to 8 bits, requiring 64 kbps per voice channel. A 32-channel PCM system using TDM requires 2 Mbps of bandwidth and can carry more voice channels than FDM with the same bandwidth.
This document summarizes different types of multiplexing techniques used in communication systems:
1) Frequency Division Multiplexing (FDM), Time Division Multiplexing (TDM), Wavelength Division Multiplexing (WDM), and Code Division Multiple Access (CDMA). FDM separates users by allocating different frequency bands, TDM separates users by assigning different time slots, WDM separates signals using different wavelengths of light, and CDMA separates users by encoding data with unique spreading codes.
2) TDM uses a commutator to sample multiple signals and transmit them serially, with each user getting a time slot. TDMA divides a time frame into slots and assigns each user a slot.
3) W
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive functioning. Exercise boosts blood flow, releases endorphins, and promotes changes in the brain which help regulate emotions and stress levels.
The document discusses time division multiplexing (TDM) and synchronous digital hierarchy (SDH) networking. It describes how TDM works by dividing bandwidth into discrete time slots and transmitting multiple signals in rapid sequence. It covers topics like TDM over PCM links, E1 and T1 framing, line codes like HDB3, synchronous vs asynchronous transmission, elastic stores, and PDH networking hierarchy. It then introduces SDH, describing how it uses containers, virtual containers, and pointers to allow flexible bandwidth allocation and adding/dropping of tributary signals.
Este documento describe dos técnicas de multiplexación utilizadas en telecomunicaciones: FDMA y TDMA. FDMA separa el espectro en distintos canales de voz asignando a cada uno una frecuencia diferente, mientras que TDMA comprime conversaciones digitales y las envía utilizando la señal de radio por tercios de tiempo, lo que permite tres veces más capacidad que sistemas analógicos equivalentes. El documento también explica cómo se utiliza TDMA en telefonía celular para dividir canales de frecuencia en ranuras de tiempo y así permitir m
Bandwidth utilization techniques allow multiple signals to be transmitted simultaneously over a single data link. Multiplexing divides the bandwidth into channels that can be assigned to different signals. There are two primary multiplexing techniques: frequency-division multiplexing (FDM) and time-division multiplexing (TDM). FDM is an analog technique that combines signals by assigning each to a different frequency band. TDM is a digital technique that combines signals by assigning each short time slots in a repeating sequence. TDM makes more efficient use of the available bandwidth than FDM.
Time division multiplexing (TDM) is a technique used in telecommunications to transmit multiple signals over a shared medium. It involves dividing a signal into multiple time slots and assigning each slot to a different signal. TDM was initially developed for telegraphy in 1870 and is now widely used. It is used in digital networks like TDM telephone networks and synchronous digital hierarchy (SDH) networks to efficiently allocate bandwidth to multiple signals or data streams. Common examples of TDM include digitally transmitting multiple telephone calls over the same cable or interleaving left and right stereo signals in an audio file.
This document discusses multiple access techniques for wireless communications, including FDMA, TDMA, and CDMA. It provides details on how each technique works and its advantages and disadvantages. FDMA divides the frequency band into channels that can be assigned to individual users. TDMA divides each channel into time slots that can be assigned to users. CDMA allows all users to use the whole available bandwidth simultaneously by using unique codes to distinguish users.
Time DIvision Multiplexing ApplicationsRohan Nagpal
Time division multiplexing (TDM) allows simultaneous transmission of multiple signals across a single data link by carrying signals at different time intervals. A research paper proposes a mixed signal built-in self-test (BIST) scheme using TDM comparators and counters to test analog circuits. The scheme converts circuit responses to digital signatures using TDM comparators. Counters connected to comparators count 1s at each time slot to generate signatures. This flexible and low-hardware scheme allows monitoring internal nodes in addition to outputs. Simulation results show the scheme can test a low-pass filter and determine a pass/fail result. The paper concludes the TDM BIST scheme provides an efficient, minimum-hardware approach for analog and mixed-
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.
The DMR standard delivers compelling benefits for professional two-way radio users by increasing spectral efficiency through a two-slot TDMA protocol. This allows significant cost savings through reduced equipment needs while also providing enhanced audio quality, longer battery life, and advanced features. DMR represents an exciting evolution for professional mobile radio and strengthens two-way radio's position as the leading communication method for mobile professionals in demanding environments.
4G is the fourth generation of mobile communications technology intended to replace 3G. It would allow for wireless internet access at much higher speeds of up to 1 Gbps for low mobility and 100 Mbps for high mobility. Key 4G technologies include OFDM, SDR, MIMO and improved handover and mobility. 4G would provide benefits like higher bandwidth, lower network costs, and access to broadband multimedia services for both operators and users.
Redline produces powerful, versatile, and reliable broadband wireless systems for delivering high-speed communications services. Their software-defined radios can be configured for various applications and upgraded without hardware changes. Redline offers the longest ranges, best coverage, highest throughput, and lowest latency of any competitor in the industry.
This document provides an overview of 4G technology. It begins with an introduction defining 4G and its objective of providing comprehensive IP solutions for voice, data and multimedia on an "anytime, anywhere" basis. The document then outlines key 4G technologies including communications architecture, ad hoc networks, smart antennas, MIMO, software defined radio, Mobile IPv6, and OFDMA. It describes applications and impacts of 4G and concludes by noting 4G promises to fulfill the goal of personal computing and communication through high data rates everywhere over wireless networks.
The Motorola AP 7181 is an outdoor, dual-band 802.11n mesh access point that delivers high network capacity and performance for enterprises. It features 3x3 MIMO technology for data rates up to 300 Mbps, dual polarized antennas for excellent coverage without self-shadowing, and Motorola's MeshConnex routing technology for efficient mesh networking. The AP 7181 is designed for flexible mounting and easy deployment to minimize costs and maximize return on investment.
The Motorola AP 7181 is an outdoor, multi-radio 802.11n mesh access point that delivers high network capacity and performance. It utilizes 802.11n technology and optimized hardware and software to achieve maximum throughput and connections for mesh networking. The dual-radio device features 3x3 MIMO and supports data rates up to 300Mbps. It provides robust mesh routing and fast handoffs for mobile applications. The AP 7181 is designed for flexible mounting and easy deployment to minimize costs.
The document discusses the evolution and capabilities of DOCSIS (Data Over Cable Service Interface Specification) technology. It notes that DOCSIS 1.0 enabled high-speed internet access over cable networks. DOCSIS 1.1 added quality of service and security features. DOCSIS 2.0 provides increased upstream bandwidth capacity to support symmetric services like voice and peer-to-peer applications. The roadmap outlines continued improvements like DOCSIS in set-top boxes and higher bandwidth to support new services.
The Motorola AP 7181 is an outdoor, multi-radio 802.11n mesh access point that delivers high network capacity and performance. It utilizes 802.11n technology and optimized hardware and software to achieve maximum throughput and connections for mesh networking. The dual-polarized antenna system allows it to achieve high data rates. The AP 7181 provides fast and stable connections for mobile applications and extends 802.11n capabilities outdoors.
The Motorola AP 7181 is an outdoor, dual-band 802.11n mesh access point that delivers high network capacity and performance using 3x3 MIMO technology. It features dual polarized antennas that achieve excellent coverage without self-shadowing. The AP 7181 supports data rates up to 300 Mbps and uses Motorola's robust MeshConnex routing technology for efficient mesh networking. It is designed for flexible mounting and easy deployment in enterprise and municipal wireless networks.
The document discusses Cambium Point-to-Point (PTP) 500 and PTP 600 wireless technologies. These technologies employ a unique combination of intelligent OFDM, adaptive modulation, dynamic frequency selection, MIMO, and other technologies to provide up to 99.999% availability in challenging environments. The PTP 500 and 600 systems deliver high throughput wireless connectivity and are optimized for applications such as video surveillance, backhaul, and disaster recovery networks.
4G networks are optimized for data and aim to provide speeds of 100Mbps for mobile users and 1Gbps for stationary users. 4G allows for lower powered radio signals, digital error checking, and the introduction of digital data services like SMS and email. However, 3G networks still face issues like high license fees and expensive phones. 4G is expected to offer faster, more reliable connections at lower costs using technologies like OFDM and potentially incorporating IEEE 802.11n standards.
The document discusses the evolution of wireless communication technologies from 1G to 4G. It provides an overview of cellular networks and wireless local area networks. The key aspects of 3G and 4G wireless systems are summarized, including services, issues, hardware requirements and user expectations for 4G. 4G is described as providing higher speeds, bandwidth and customized services across a variety of access technologies compared to 3G.
The document discusses the evolution of wireless communication technologies from 1G to 4G. It provides an overview of cellular networks and wireless local area networks. The key aspects of 3G wireless systems are described, including services provided and issues. 4G wireless is characterized as providing high speeds, customized services, and support for multimedia. The technologies, hardware, services, and expected user segments of 4G are outlined. Comparisons are made between requirements and technologies of 3G and 4G wireless systems.
This document provides a summary of a term paper on cognitive radio. It discusses key topics such as:
- What cognitive radio is and its main features of intelligent awareness and reconfigurability.
- The inefficiencies of current static spectrum allocation and how cognitive radio can help address spectrum scarcity issues.
- Drivers for cognitive radio like dynamic spectrum access and cognitive radio networks.
- Challenges to deploying cognitive radio like legal hurdles, security issues, and technology hurdles related to spectrum sensing.
- Promising applications of cognitive radio in areas like emergency services, internet access, and rural connectivity.
This document provides a summary of a term paper on cognitive radio. It discusses key topics such as what cognitive radio is, its advantages over static spectrum allocation, key drivers for cognitive radio like dynamic spectrum access and cognitive radio networks, challenges to deployment including legal hurdles, security issues, and technology hurdles related to spectrum sensing. Promising applications of cognitive radio mentioned include emergency services, low cost internet access, and new services enabled by intelligent radio-based advertising.
This document provides a summary of a term paper on cognitive radio. It discusses key topics such as:
- What cognitive radio is and its main features of intelligent awareness and reconfigurability.
- The inefficiencies of current static spectrum allocation and how cognitive radio can help address spectrum scarcity issues.
- Drivers for cognitive radio like dynamic spectrum access and cognitive radio networks.
- Challenges to deploying cognitive radio like legal hurdles, security issues, and technology hurdles related to spectrum sensing.
- Promising applications of cognitive radio in areas like emergency services, internet access, and rural connectivity.
rafkwnshru2ocnal9ta1-signature-a1b6820cbe628a2a167a0a81f2762fc8f340dd4b93d47a...Mathavan N
The document discusses software defined radios and their evolution. It provides definitions of software radio and describes how radios have evolved from hardware-based to more software-based designs with digital signal processing and software reconfiguration. This allows for greater flexibility, easier upgrades, and lower costs. It outlines the progression from 1G to 2G to 3G cellular networks and how each generation incorporated more software to handle increasing complexity. The benefits of software defined radios are provided for various stakeholders. Finally, it discusses the ideal software radio architecture and challenges in implementation.
Meru Retailer Presentation 18 October 2006Meru Networks
Meru Networks provides a converged wireless LAN platform that sits at the high end of technology and offers the lowest total cost of ownership. Their platform is interoperable with existing networking infrastructure and can be used to create an all-wireless enterprise. Meru targets markets with critical data, voice, and video applications including healthcare, education, retail, enterprise, and government facilities. For retailers specifically, their platform enables mobility for knowledge workers, accommodates growing mobile technologies, and drives productivity and profitability through cost savings. It provides reliable conduits for information sharing using toll-quality voice, video, and data transmission over a single wireless network.
Digital Mobile Radio (DMR) is an open digital radio standard defined by ETSI that uses two-slot TDMA to allow two voice calls within a single 12.5kHz channel, doubling capacity compared to analog. DMR Tier II covers licensed conventional systems operating from 66-960MHz and provides spectral efficiency, advanced features, and integrated IP data. DMR systems offer improved audio clarity, longer battery life, and a migration path from analog to digital radios.
Cambium Networks is an industry leader in point-to-multipoint and point-to-point wireless broadband solutions. They have shipped over 4 million nodes totaling over $1 billion to networks in more than 150 countries. Their ePMP product line provides affordable and scalable wireless access networks through features like GPS synchronization, high scalability and consistent performance, interference mitigation technology, and effective quality of service capabilities.
The VX 9000 virtualized software-based wireless LAN controller combines the power of virtualization with Motorola Solutions' WiNG Controller. It provides centralized management of wireless networks through a single interface with high scalability, flexibility and advanced wireless services. Key features include integrated network security, the advanced WiNG 5 operating system, plug-and-play deployment, simplified licensing and infinite scalability through virtualization. It supports all major hypervisors and public/private clouds for maximum deployment flexibility at low cost.
The NX 7500 integrated services platform provides comprehensive management of up to 2,048 network elements through a single interface. It allows all network infrastructure to intelligently route traffic for maximum speed and throughput without congestion. The NX 7500 offers advanced wireless LAN performance for mid-sized and campus environments with features such as plug-and-play installation, hierarchical management, smart routing, BYOD support, and integrated security services. It provides flexibility and investment protection through modular upgrades.
The document discusses the challenges retailers face in supporting increased wireless applications and next-generation Wi-Fi in stores. It introduces the Motorola AP 8200 Series as a solution that provides high-performance wireless connectivity for customers and staff. The AP 8200 Series allows easy access, security, support for 802.11ac Wi-Fi, bandwidth for applications, and performance for many users. It provides flexibility, a cost-effective upgrade to 802.11ac, and features for security, environmental monitoring, location services, and more.
The document describes the innovative features of the Motorola AP 8222 wireless access point. It has a sleek design suitable for retail, office, and other customer-facing spaces. It provides dual-band 802.11ac and 802.11n wireless connectivity at speeds up to 1.3Gbps. Key features include advanced beamforming, gap-free security, and support for bandwidth-heavy applications like video calling. The access point is centrally managed through Motorola's WiNG 5 networking operating system.
The AP 8163 is a ruggedized outdoor mesh access point designed to withstand extreme weather conditions. It has three radios - two for client access across 2.4GHz and 5GHz bands, and a third radio that can be used for wireless intrusion prevention scanning or dynamic frequency selection to avoid radar interference. The advanced WiNG 5 operating system allows the access points to self-optimize the network for best performance. Key features include powerful antennas for extended range, mesh networking for redundancy, and security features like firewalls and wireless intrusion prevention.
The document describes the features and capabilities of the Motorola AP 8122 3x3 MIMO 802.11n access point. It delivers high throughput to support enterprise applications including voice and HD video using 802.11n technology with standard 802.3af PoE. It has advanced features like load balancing, pre-emptive roaming, and dual band radios to increase network reliability, resilience, and security. The access point also supports advanced wireless capabilities such as voice over wireless, location services, and guest access controls.
The document describes the innovative features of the AP 7532 wireless access point. It provides the highest wireless speeds available with 3x3 MIMO and 256 QAM modulation on both 2.4GHz and 5GHz radios. It has a dual radio 802.11ac/802.11n design that provides a upgrade path to 1.3Gbps 802.11ac speeds while maintaining support for existing devices. It offers various advanced features like load balancing, security, sensor support and quality of service for voice. The access point is designed to deliver maximum performance at a low cost.
The AP 7502 is a dual-band 802.11ac wireless access point designed for installation in small spaces like hotel rooms. It has a compact wall-mount design, supports the latest WiFi standards, and includes features to ensure reliable connectivity even in challenging environments. Setup and management are simplified through zero-touch provisioning and both standalone and controller-based operation modes.
The document describes the innovative features of the AP 7522 wireless access point. It provides dual-band 802.11ac and 802.11n radios for high performance WiFi. It offers internal or external antenna options and can function as both an access point and wireless sensor. The access point provides security, load balancing, and other features to support mission critical applications on the wireless network.
Unveiling the Dynamic Personalities, Key Dates, and Horoscope Insights: Gemin...my Pandit
Explore the fascinating world of the Gemini Zodiac Sign. Discover the unique personality traits, key dates, and horoscope insights of Gemini individuals. Learn how their sociable, communicative nature and boundless curiosity make them the dynamic explorers of the zodiac. Dive into the duality of the Gemini sign and understand their intellectual and adventurous spirit.
Industrial Tech SW: Category Renewal and CreationChristian Dahlen
Every industrial revolution has created a new set of categories and a new set of players.
Multiple new technologies have emerged, but Samsara and C3.ai are only two companies which have gone public so far.
Manufacturing startups constitute the largest pipeline share of unicorns and IPO candidates in the SF Bay Area, and software startups dominate in Germany.
The APCO Geopolitical Radar - Q3 2024 The Global Operating Environment for Bu...APCO
The Radar reflects input from APCO’s teams located around the world. It distils a host of interconnected events and trends into insights to inform operational and strategic decisions. Issues covered in this edition include:
SATTA MATKA DPBOSS KALYAN MATKA RESULTS KALYAN CHART KALYAN MATKA MATKA RESULT KALYAN MATKA TIPS SATTA MATKA MATKA COM MATKA PANA JODI TODAY BATTA SATKA MATKA PATTI JODI NUMBER MATKA RESULTS MATKA CHART MATKA JODI SATTA COM INDIA SATTA MATKA MATKA TIPS MATKA WAPKA ALL MATKA RESULT LIVE ONLINE MATKA RESULT KALYAN MATKA RESULT DPBOSS MATKA 143 MAIN MATKA KALYAN MATKA RESULTS KALYAN CHART
The Steadfast and Reliable Bull: Taurus Zodiac Signmy Pandit
Explore the steadfast and reliable nature of the Taurus Zodiac Sign. Discover the personality traits, key dates, and horoscope insights that define the determined and practical Taurus, and learn how their grounded nature makes them the anchor of the zodiac.
[To download this presentation, visit:
https://www.oeconsulting.com.sg/training-presentations]
This presentation is a curated compilation of PowerPoint diagrams and templates designed to illustrate 20 different digital transformation frameworks and models. These frameworks are based on recent industry trends and best practices, ensuring that the content remains relevant and up-to-date.
Key highlights include Microsoft's Digital Transformation Framework, which focuses on driving innovation and efficiency, and McKinsey's Ten Guiding Principles, which provide strategic insights for successful digital transformation. Additionally, Forrester's framework emphasizes enhancing customer experiences and modernizing IT infrastructure, while IDC's MaturityScape helps assess and develop organizational digital maturity. MIT's framework explores cutting-edge strategies for achieving digital success.
These materials are perfect for enhancing your business or classroom presentations, offering visual aids to supplement your insights. Please note that while comprehensive, these slides are intended as supplementary resources and may not be complete for standalone instructional purposes.
Frameworks/Models included:
Microsoft’s Digital Transformation Framework
McKinsey’s Ten Guiding Principles of Digital Transformation
Forrester’s Digital Transformation Framework
IDC’s Digital Transformation MaturityScape
MIT’s Digital Transformation Framework
Gartner’s Digital Transformation Framework
Accenture’s Digital Strategy & Enterprise Frameworks
Deloitte’s Digital Industrial Transformation Framework
Capgemini’s Digital Transformation Framework
PwC’s Digital Transformation Framework
Cisco’s Digital Transformation Framework
Cognizant’s Digital Transformation Framework
DXC Technology’s Digital Transformation Framework
The BCG Strategy Palette
McKinsey’s Digital Transformation Framework
Digital Transformation Compass
Four Levels of Digital Maturity
Design Thinking Framework
Business Model Canvas
Customer Journey Map
IMPACT Silver is a pure silver zinc producer with over $260 million in revenue since 2008 and a large 100% owned 210km Mexico land package - 2024 catalysts includes new 14% grade zinc Plomosas mine and 20,000m of fully funded exploration drilling.
❼❷⓿❺❻❷❽❷❼❽ Dpboss Matka Result Satta Matka Guessing Satta Fix jodi Kalyan Final ank Satta Matka Dpbos Final ank Satta Matta Matka 143 Kalyan Matka Guessing Final Matka Final ank Today Matka 420 Satta Batta Satta 143 Kalyan Chart Main Bazar Chart vip Matka Guessing Dpboss 143 Guessing Kalyan night
The Genesis of BriansClub.cm Famous Dark WEb PlatformSabaaSudozai
BriansClub.cm, a famous platform on the dark web, has become one of the most infamous carding marketplaces, specializing in the sale of stolen credit card data.
SATTA MATKA DPBOSS KALYAN MATKA RESULTS KALYAN CHART KALYAN MATKA MATKA RESULT KALYAN MATKA TIPS SATTA MATKA MATKA COM MATKA PANA JODI TODAY BATTA SATKA MATKA PATTI JODI NUMBER MATKA RESULTS MATKA CHART MATKA JODI SATTA COM INDIA SATTA MATKA MATKA TIPS MATKA WAPKA ALL MATKA RESULT LIVE ONLINE MATKA RESULT KALYAN MATKA RESULT DPBOSS MATKA 143 MAIN MATKA KALYAN MATKA RESULTS KALYAN CHART
2. contents
3 Executive Summary
4 Advantages of Digital Two-Way Radio
5 Digital Radio Market and Standards
7 Multiple Access and Spectral Efficiency
7 TDMA: How It Works
9 Advantages of Two-Slot TDMA for
Professional Organizations
12 The Right Choice for Professional
Two-Way Digital Radio: TDMA
TDMA Technology
3. Executive Summary
Licensed, professional two-way radio is on the verge of making the biggest leap forward since the
invention of the transistor — the move from analog to digital. Digital radio offers many advantages
over analog, including improved voice quality at greater range, better privacy, sophisticated call-control
features, the ability to easily integrate with data systems, and more.
We’re now at the beginning of what will quickly become a large-scale migration to digital radio in
professional applications. At the same time, regulatory pressures combined with real-world operating
needs are driving radio manufacturers and users to communicate more information in a given slice of
RF spectrum — in other words, to increase “spectral efficiency.” Channels that historically carried a
single call at a time are now being divided so they can carry two.
Two technologies exist to enable this “splitting” of channels, allowing multiple access on a single
channel. Frequency-Division Multiple Access (FDMA) splits the channel frequency into two smaller
sub-channels that can carry separate calls side-by-side. Time-Division Multiple Access (TDMA)
preserves the full channel width, but divides it into alternating time slots that can each carry an
individual call. Both technologies are already being used in North America to accomplish the FCC-
mandated split of 25 kHz channels into 12.5 kHz channels, and they’re both being used worldwide
to accomplish similar increases in spectral efficiency whether currently mandated or not.
In the coming years, new regulations will almost certainly require improvements in the effective
capacity of 12.5 kHz channels: it is only a matter of time before the ability to carry two voice paths in
a single 12.5 kHz channel — also known as 6.25 kHz equivalent efficiency — becomes a requirement.
But because the technology exists today to accomplish this goal, there’s no need for professional
radio users to wait for the regulations to catch up with benefits that are immediately available. Even
in the absence of a mandate, professional users can double the capacity of their existing licensed
channels by adopting digital technologies that enable 6.25 kHz equivalent efficiency. With potential
benefits including increased capacity, lower equipment costs, data integration, added features, and
more, now is a compelling time for analog radio users to make the switch to digital systems that offer
6.25 kHz equivalency.
This white paper examines the two leading digital modulation technologies that are capable of
achieving this doubling of spectral efficiency: 6.25 kHz FDMA and two-slot 12.5 kHz TDMA.
Businesses looking to migrate to the most efficient professional digital systems to achieve
greater capacity and performance will need to choose one or the other — FDMA and TDMA
are not interoperable.
Two-slot 12.5 kHz TDMA-based systems, providing 6.25 kHz equivalency is the right choice for most
mobile professionals. Professional radio standards based on TDMA technology are already widely
used around the world, and future requirements for even greater spectral efficiency are almost certain
to be based on TDMA as well. Today and tomorrow, TDMA technology provides advantages of
feature flexibility, lower equipment costs, longer battery life, future-readiness, and the proven ability
to increase spectral efficiency without risking increased congestion or radio channel interference.
TDMA Technology
4. Advantages of Digital Two-Way Radio
Since the first wireless transceiver was installed in a Bayonne, New Jersey police car in
1933, two-way radio has been a mission-critical technology for police, firefighters, search
and rescue workers and others on the front lines of public safety. And increasingly, as new
models have reduced the size and cost of two-way radios, the technology has been adopted
by business professionals as well.
Industries including transportation, education, construction, manufacturing, energy and
utilities, private security, government, hospitality, retail, and many others are finding that two-
way radio can improve efficiency, worker productivity, and responsiveness by allowing mobile
teams to share business and customer information instantly.
Through most of its history, two-way radio has meant analog voice — the representation of
sound waves as either amplitude modulated (AM) or frequency modulated (FM) radio waves.
In fact, this is one of the last areas of professional communications to be touched by digital
technology. But that’s changing, very quickly, for very good reasons.
Modulating the voice into digital signals, rather than analog, provides several advantages.
First and foremost, digital technology provides better noise rejection and preserves voice
quality over a greater range than analog. Especially at the farthest edges of the transmission
range, users can hear what’s being said much more clearly — increasing the effective range
of the radio solution and keeping users responsive to changing situations in the field.
Depending on the technologies used, digital systems can also be designed to:
• Make more efficient use of available, licensed RF spectrum
• Combine voice and data access in the same device, delivering more information while
empowering field workers with systems that are more portable, flexible, and much easier
to use than two different and incompatible systems
• Enable integration and interoperability with back-end data systems and external systems
• Combine analog and digital voice in the same device, easing the migration to digital while
preserving investments in analog technology
• Provide strong, practical, easy-to-use privacy solutions without the significant loss in voice
quality that analog scrambling can cause
• Enable flexible and reliable call control and signaling capabilities
• Flexibly adapt to changing business needs and new applications through a modular architecture
DIGITAL
Enhanced Digital Excellent
Audio Performance audio quality
Area of Improved
Performance
AUDIO QUALITY
ANALOG
coverage
Minimal Acceptable Audio Quality
Digital voice retains better
quality than analog as signal Poor
strength decreases.
Strong SIGNAL STRENGTH Weak
TDMA Technology
5. The clear advantages of digital radio — along with increasing regulatory pressures to use RF
spectrum more efficiently — will drive widespread adoption of professional two-way digital
radio solutions in the coming years. If you’re using analog today, you’ll almost certainly be
migrating to digital tomorrow. Now is the time to research the available technologies so
that, when you’re ready to make the move, you’ll choose systems that provide the greatest
benefit over the long term.
Digital Radio Markets and Standards
Although the market landscape for two-way radio varies somewhat throughout the world,
markets can be roughly divided into three broad categories: (1) commercial and light
industrial applications, (2) professional, business-critical applications, and (3) mission-critical
public safety applications. With some overlap, there are relevant digital two-way radio
standards that are generally applicable to each of these categories.
While we won’t get into the specific regulatory requirements governing radio in various
countries and regions, let’s take a closer look at how the most important, internationally
recognized standards map to the needs of users within the general market categories. An
understanding of the entire market landscape will provide context for our discussion of the
needs of users in the professional/business-critical category.
Market Categories Example Vertical Markets Digital Radio Standards
Emergency Services
Public Safety/
ETSI TIA Project 25 Licensed
Mission Critical Public Transport
TETRA Licensed Trunking Conventional Trunking
Airports/Ports Local Government
Transportation Mining
Professional/
Petrochemical Public Utilities ETSI
Business Critical DMR Tier 2: Licensed Conventional
Manufacturing Taxi DMR Tier 3: Licensed Trunking
Construction Rental Agencies
Private Security
Commercial ETSI
Warehousing
Retail DMR Tier 1: Unlicensed On-site Technologies
Worldwide digital two-way Light Industrial
Agriculture dPMR Tier 1: Unlicensed
radio markets can be roughly Hospitality
divided into three categories
Commercial and Light Industrial. Multiple relevant digital technologies exist for
this market, including on-site digital technologies such as Frequency Hopping Spread
Spectrum (FHSS) utilized in unlicensed 900 Mhz and 2.4 GHz bands. The European
Telecommunications Standards Institute, or ETSI, has also defined two Tier-1 protocols for
digital mobile radio (DMR) in the unlicensed PMR446 band; the DMR Tier-1 protocol utilizes
12.5kHz FDMA, while the dPMR protocol utilizes 6.25kHz FDMA. Both protocols provide
for consumer applications and low-power commercial applications, using a maximum of
0.5 watt RF power. With a limited number of channels and no use of repeaters, no use of
telephone interconnects, and fixed/integrated antennas, Tier-1 DMR/dPMR devices are best
suited for personal use, recreation, small retail and other settings that don’t require wide
area coverage and advanced features.
Mission-Critical Public Safety. This market category is defined by mission-critical
communications, security, and interoperability needs. In countries covered by ETSI, a
relevant digital standard is the TErrestrial Trunked RAdio (TETRA) standard, which is used
to support multiple talk groups on multiple frequencies, including one-to-one, one-to-many
and many-to-many calls. TETRA is a digital standard that uses four-slot TDMA in 25 kHz
channels to increase spectral efficiency and allow multiple access.
TDMA Technology
6. In the U.S., the Telecommunications Industry Association (TIA) has established Project 25
to define similar capabilities for the mission-critical market. Unlike TETRA, Project 25 Phase I
uses 12.5 kHz channels and currently uses FDMA for both trunked and conventional digital
systems. Phase II will add two-slot TDMA capabilities for digital trunked radio. Both TETRA
and Project 25-compliant systems rely on sophisticated infrastructure to achieve the fault-
tolerant reliability and advanced calling functionality required in public-safety and other
mission-critical applications.
Business-Critical Professional. In between the commercial/light industrial and mission
critical/public safety market categories lies a huge market for organizations who aren’t
engaged in mission-critical work and don’t have the budget or need for expensive, fault-
tolerant infrastructure—but who can still benefit from increased capacity in licensed channels,
advanced features, wide area coverage and other benefits usually associated with mission-
critical systems. Businesses in this category include transportation, education, construction,
manufacturing, private security, small municipalities, and many other industries.
The ETSI DMR Tier-2 standard is the relevant digital radio standard targeted to these
users, providing spectral efficiency, advanced voice features and integrated IP data
services in licensed bands for high-power communications. ETSI DMR Tier-2 calls for two-
slot TDMA in 12.5 kHz channels. Two-slot TDMA technology is the primary focus of our
discussion in this paper.
Analog radios have been used in business-critical applications for years. However, as
manufacturers introduce high power digital radios to this market, they have a choice: they
can either build their communications system using a proprietary technology such as digital
6.25kHz FDMA, or they can leverage standards-based TDMA. The two are not compatible
or interoperable.
Motorola believes that two-slot TDMA is the best fit for most professional, business-
critical digital two-way radio applications. Moreover, ETSI has selected TDMA as the
standard protocol for Tier-2 professional two-way radio applications, and it satisfies ETSI
channel emissions requirements and goals for spectral efficiency. Although the FCC does
not mandate standard protocols, devices conforming to the ETSI Tier-2, two-slot TDMA
standard will meet existing FCC channel emissions requirements for 12.5 kHz channels
and exceed forward-looking requirements for spectral efficiency in the U.S. With technical
advantages for the professional market, and the backing of the world’s most influential
telecommunications standards bodies, two-slot TDMA is the clear choice for organizations
looking to deploy new digital two-way radio systems, or to upgrade their existing analog
radio to digital.
Let’s take a closer look at two-slot TDMA and why it’s the best multiple-access technology
for the majority of professional applications.
TDMA Technology
7. Multiple Access and Spectral Efficiency
The primary goal of any multiple-access RF technology is to achieve greater spectral
efficiency, allowing more users to share a given channel in the licensed RF spectrum.
Historically, the licensed airwaves were divided into relatively large 25 kHz channels. There
was plenty of room for the broadcasters using these channels to exist side-by-side, without
significant interference problems. Over the years, however, the airwaves have become
increasingly crowded, creating a need for new standards and technologies that allow more
radio users to share the available spectrum in any given area.
The demand for greater spectral efficiency is being driven, in part, by regulatory agencies.
In the U.S., for example, the FCC is requiring manufacturers to offer only devices that
operate within 12.5 kHz VHF and UHF channels by 2011. By the year 2013, all VHF and
UHF users will be required to operate in 12.5 kHz — making it possible for roughly twice as
many users to share the airwaves as compared with today’s 25 kHz licenses.
The next logical step is to further improve the effective capacity of 12.5 kHz channels. While
there’s no current mandate requiring a move to 6.25 kHz, discussions are continuing at the FCC
and other agencies, and it’s only a matter of time before the ability to carry two voice paths in a
single12.5 kHz channel, also known as 6.25 kHz equivalent efficiency, becomes a requirement in
VHF and UHF bands. In the meantime, two-slot TDMA offers a way to divide a 12.5 kHz channel
into two independent time slots, achieving 6.25 kHz-equivalent efficiency today.
With two-slot TDMA-based devices, there’s no reason to wait for a government mandate
to achieve more capacity on existing licensed channels. Business can take the initiative to achieve
greater spectral efficiency well ahead of the inevitable regulations — and ahead of the competition.
And even without a regulatory mandate, greater spectral efficiency offers many operational
benefits. We’ll discuss those benefits later, but first let’s explore how two-slot TDMA works.
TDMA: How It Works
TDMA stands for “Time-Division Multiple Access.” Like FDMA, or “Frequency-Division Multiple
Access,” TDMA is a technology that allows multiple conversations to share the same radio
channel. Although the goal is the same, the two technologies work very differently.
6.25 kHz FDMA
In FDMA, a channel frequency is split into smaller subdivisions — for example, splitting
a 25 kHz band into two narrower “sub-channels” that transmit side-by-side to achieve
12.5 kHz equivalent spectral efficiency. The same technique can be used to achieve 6.25
kHz equivalent efficiency in a 12.5 kHz channel — although how well this technique will
perform hasn’t yet been established in real-world implementations on a large scale.
As the subdivisions of a licensed channel become narrower, there’s a growing likelihood
of problems due to congestion and interference in an FDMA-based 6.25 kHz-equivalent
system, as shown in the illustration.
12.5 kHz Channel Regulatory
Emissions Mask
12.5 kHz Signal 6.25 kHz 6.25 kHz
When FDMA technology is used to split Signal Signal
a channel into two sub-channels, the
resulting signals must still fit within the
channel’s required emissions mask 12.5 kHz Channel 12.5 kHz Channel
TDMA Technology
8. When you try to squeeze two 6.25 kHz signals into one 12.5 kHz channel, you still have
to meet the channel’s regulatory emissions mask. In order to do, the signal deviation
(represented by the height and width of the lobes in the illustration) must necessarily be
smaller than what can be achieved with a single 12.5 kHz signal. This smaller deviation
means reduced sensitivity, which in turn reduces effective signal range in real world
conditions. At the same time, there is very little tolerance for errors introduced by oscillator
aging, and the 6.25 kHz signal contains more energy near the edges of the mask — making
it more prone to adjacent channel interference and near/far interference problems. This
results in reduced quality of service in real world conditions.
Two-Slot TDMA
By comparison, TDMA offers a proven method for achieving 6.25 kHz equivalency in
12.5 kHz repeater channels — a major benefit for users of increasingly crowded licensed
bands. Instead of dividing the channel into two smaller slices, TDMA uses the full channel
width, dividing it into two alternating time slots. As a result, TDMA essentially doubles
repeater capacity while preserving the well-known RF performance characteristics of the
12.5 kHz signal.
Voice Call 1
Time Slot 1 Time Slot 2 Time Slot 1 Time Slot 2
Voice Call 2
or Data Exchange
TDMA divides a 12.5 kHz channel into two alternating time slots to achieve
6.25 kHz equivalent spectral efficiency when used with a repeater.
From the perspective of RF physics — that is, actual transmitted power and radiated
emissions — the 12.5 kHz signal of two-slot TDMA occupies the channel, propagates,
and performs essentially the same as today’s 12.5 kHz analog signals. With the added
advantages of digital technology, TDMA-based radios can work within a single repeater
channel to provide roughly twice the capacity of analog while offering RF performance
equivalent to, or better than, today’s analog radio.
As we will see, the two time slots can potentially be used for a variety of purposes.
Most organizations considering TDMA-based two-way radio will probably be interested in
doubling the voice capacity per licensed repeater channel. By enabling 6.25 kHz equivalency,
TDMA supports two simultaneous, independent half-duplex calls in a single 12.5 kHz
repeater channel.
TDMA Technology
9. If you’re used to thinking about analog radio, this two-for-one capacity in two different
time slots might seem problematic. Wouldn’t the two calls cut in and out as the time slots
alternate, making both conversations nearly impossible to understand?
But remember, this is the digital world, where voices are encoded in bits. Although analog
signals represent the actual duration of spoken words, digital signals can encode that
duration in a way that allows for significant compression without compromising voice
quality. Each TDMA time slot is quite brief — on the order of 30 milliseconds. The circuitry
that translates voice into bits is actually able to pack 60 milliseconds worth of digitized
speech into each 30 millisecond time slot. The receiver, in turn, unpacks those bits into
speech that has its full 60 millisecond time value.
That’s why, with TDMA, two conversations can happen simultaneously and seamlessly via
a single repeater. The alternation of time slots is something that happens in the technology
only, not in the user’s experience. In fact, digital technology offers better background
noise suppression than analog while preserving the integrity of the signal at the farthest
reaches of the transmitter’s range — so both digital conversations are likely to be much
clearer than a single analog conversation would be over the same channel. And because
both conversations use the channel’s full bandwidth, there’s no degradation in range
performance, and no added risk of interference with adjacent channels.
Advantages of Two-Slot TDMA for Professional Organizations
If you’re in the professional two-way radio category, and you’re looking for increased system
capacity in 12.5 kHz channels along with higher performance and advanced features enabled
by digital radio solutions, you need to decide which technology to choose: 6.25 kHz FDMA or
12.5 kHz two-slot TDMA. 12.5 kHz FDMA remains an important technology in analog radio
systems, and is currently the standard for mission-critical digital radio under Project 25, Phase I.
However, 6.25 kHz FDMA is not well-proven and does not fit cleanly into today’s 12.5 kHz
channel structure. Professionals looking for a digital solution should strongly consider two-slot
TDMA for the many advantages it provides.
Increased Spectral Efficiency
As we have discussed, two-slot TDMA offers a proven way to enable 6.25 kHz
equivalent efficiency in licensed 12.5 kHz repeater channels. This doubles per-channel
communications capacity, while satisfying future regulatory requirements for 6.25
kHz equivalent efficiency. And unlike 6.25 kHz transmission methods build on FDMA
technology, TDMA fits seamlessly into existing licensed channel structures in UHF and VHF
— known performance, no need for rebanding or relicensing, and no risk of new forms of
radio channel interference. The choice of TDMA digital technology makes it quick and easy
to gain spectrum efficiency and improve your two-way radio communications.
Lower Equipment Costs
Compared to 6.25 kHz FDMA, two-slot TDMA allows you to achieve 6.25 kHz equivalent
efficiency while minimizing investments in repeaters and combining equipment. This is one
reason why TDMA is so well suited to professional applications, where the budget for two-
way digital radio may be limited compared to the mission-critical tier.
FDMA requires a dedicated repeater for each channel, plus expensive combining
equipment to enable multiple frequencies to share a single base-station antenna. It can
be particularly expensive to make combining equipment work with 6.25 kHz signals, and
there’s typically a loss in signal quality and range when it’s used this way.
In contrast, two-slot TDMA achieves two-channel equivalency using single-channel
equipment. No extra repeaters or combining equipment is required.
TDMA Technology
10. Advanced Features and Flexibility
In a traditional FDMA two-way radio implementation, each transmission occupies a full
12.5 kHz channel. A single channel can accommodate a single, half-duplex call. Proprietary
implementations that use FDMA to achieve two 6.25 kHz equivalent channels enable two
conversations to take place within a 12.5 kHz channel — but again, both of these conversations
are half-duplex, and there’s no flexibility to put the extra capacity to any other use.
TDMA-based digital systems with two time slots aren’t bound by these technical
restrictions. The two time slots can be used to carry two half-duplex conversations —
as with the two sub-channels in an FDMA-based system — but with no need for extra
equipment and no danger of reduced performance. Unlike FDMA, however, it’s also
possible to use the second TDMA time slot for other purposes.
For example, device designs for the first-generation of TDMA-based two-way radio
include the ability to use the second time slot for reverse-channel signaling. This capability
can be used for priority call control, remote-control of the transmitting radio, emergency
call pre-emption, and more. The second time-slot could also be used for transmitting
application data such as text messaging or location data in parallel with call activity —
a useful capability, for example, in dispatch systems that provide both verbal and visual
dispatch instructions.
TDMA-based systems also offer the flexibility to adapt as new applications emerge to
make additional use of the two time slots — preserving initial investments while providing
an open path to future usage models for digital two-way radio. For example, the future
roadmap for two-slot TDMA applications includes the ability to temporarily combine slots
for increased data rates, or to use both slots together to enable full-duplex private calls.
Additional capabilities will also emerge, as driven by the real-world needs of two-way radio
users in the professional marketplace. By choosing TDMA, professionals can immediately
gain benefits such as 2:1 voice capacity and reverse-channel signaling within a single
channel, with the option to add other capabilities as they become available. FDMA, in
contrast, is optimized for a single purpose — half-duplex calling.
One call per
repeater and channel
Two-channel Analog or Digital FDMA System
Repeater 1
Frequency 1
Combining
Equipment
Repeater 2
Frequency 2
Radio Groups
Two calls per
repeater and channel
Two-channel Digital TDMA System
TDMA saves licensing and equipment
costs by enabling the equivalent of
two 6.25 kHz channels within a single Repeater
licensed 12.5 kHz channel Frequency 1
Radio Groups
10 TDMA Technology
11. Longer Battery Life
One of the biggest challenges with mobile devices has always been battery life. In the
past, there have only been a couple of options for increasing the talk time on a single
battery charge. One way is to increase battery capacity. Battery manufacturers have
already done a remarkable job of maximizing capacity, but further gains are only possible by
increasing the size of the battery pack — and therefore decreasing portability.
The other option is to decrease transmit power, which is by far the most energy-intensive
function of two-way radio. But this means decreasing transmission range and increasing
the potential for interference from other devices — an unacceptable tradeoff in
professional situations.
Two-slot TDMA provides another, very effective option. Since each call uses only one of the
two slots, it requires only half of the transmitter’s capacity. The transmitter is idle half the
time — that is, whenever it’s the unused time-slot’s “turn.”
For example, in a typical duty cycle of 5 percent transmit, 5 percent receive, and 90
percent idle, the transmit time accounts for roughly 80 percent of the total current drain
on the radio’s battery. By cutting the effective transmit time in half, two-slot TDMA can
thus enable an up to 40 percent reduction in current battery drain, or an up to 40 percent
improvement in talk time. As a result, overall battery consumption per call is dramatically
reduced, enabling much longer usage time in the field between recharges. Modern digital
devices also include sleep and power-management technologies that increase battery life
even further.
The Right Choice for Professional
Two-Way Digital Radio: TDMA
For professional users, digital two-way radio in licensed bands is the wave of the future.
Whether they’re using analog radio today, or looking to implement their first two-way radio
system, business organizations of all kinds will soon be choosing their first digital two-
way radio solutions. The advantages and opportunities are simply too great to ignore — in
transportation, education, construction, manufacturing, energy and utilities, private security,
small municipalities and many other industries.
For most enterprises in these professions, TDMA provides the best method for achieving
6.25 kHz equivalent efficiency in licensed 12.5 kHz channels:
• TDMA is being leveraged in European and U.S. standards initiatives aimed at providing
greater spectral efficiency for the land mobile radio market.
• Unlike FDMA methods of rebanding existing channels into discrete 6.25 kHz channels,
properly designed
two-slot TDMA systems fit cleanly into existing channel structures, with no rebanding or
relicensing necessary.
• TDMA improves capacity today, while offering a path to compliance with further channel
efficiency requirements that may be mandated in the future.
• Because it increases capacity without the need for additional repeaters and other
infrastructure, TDMA can lower the overall costs of implementing digital two-way radio.
• TDMA offers the performance and flexibility to support the functional requirements of
mobile professionals in virtually any industry.
11 TDMA Technology