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Which modulation technique is used in gsm?
GSM uses GMSK modulation scheme. GPRS also uses GMSK modulation scheme. EDGE and UMTS uses 8-PSK.
What is gfsk modulation?
whatbis GMSK MODULATION ?
What is the different between segmentation and multiplexing?
AnswerMODULATION:Usually, the signal that we want to transmit, say a speech signal with 4000 Hz frequency, will require a very big antenna. For any signal the frequency f is related to wavelength Lasc = L * f ………………………… (i)Where c is velocity of light. And antenna length is generally taken as L/2 which simply means for our case antenna length is 75000 m, obviously this size of antenna is too big to use on day to day basis. That is why we take our speech signal or the desired signal and take another high frequency signal known as carrier (carrier can be any signal but should have high frequency and in practice we use a simple continuous wave signal), now we alter one or more parameters of this career signal in accordance with our desired signal, this parameters can be any one or combination of parameters. The basic parameters are amplitude, frequency, and phase of the signal. The result of this alteration we get is known as modulated signal, the desired signal which we wanted to transmit is known as modulating signal also known as base band signal and modulated signal is also known as band pass signal. The whole process is known as MODULATION.There are many types of modulation starting from amplitude modulation popularly known as AM, frequency modulation (FM), QPSK, PCM, GMSK, QAM etc.MULTIPLEXING:Basically there are two types of system, time domain and frequency domain. In time domain we transmit frames, and in frequency domain we transmit in accordance with frequency. Now if there is more than one source of signal and we want to transmit them together then we implement multiplexing. In multiplexing we mix the source signals (off course with some precautions) say if we want to mix them in time domain then our frame will contain some packets form source A and some packets from source B and so on depending upon the constraints of the channel and time frame. The signals that source are generating can either be modulated signals or we can even send our multiplexed signal to the modulator and then modulate the signal. At the receiving end be demultiplex the signals. In multiplexing we do not provide a dedicated resource to a single source. I.e. we do not dedicate the complete time frame to a single source (in our case it is time frame). Multiplexing is also seen as you are travelling on a four lane road and suddenly it get narrower and turned to single lane, at this point the traffic police will allow one car from each lane to drive through that narrow single lane, this is what we called MULTIPLEXING.MULTIPLE ACCESS:As the name suggest, multiple access means multiple users can access the channel or link. Multiple access provides dedicated resources to the user (with a time constraint) in comparison to the multiplexing which does not provide any type of resources. There are many type of Multiple access schemes like FDMA frequency division multiple access, TDMA time division multiple access, CDMA code division multiple access, SDMA space division multiple access etc. take the example of FDMA, the whole frequency band is divided into small frequency bands called channels, now each channel is having certain capacity to take the traffic say a channel can accommodate single user at time, then the whole frequency bandwidth can be access by as many users as there are channels, mathematically if we are having a bandwidth of 200 KHz and channel bandwidth is 50 KHz then it means we can accommodate 4 users at a time by giving 50 KHz channel to each. This is so called multiple access, i.e. multiple users can access the bandwidth simultaneously and we do not require any additional hardware at the receiving end to separate the desired user from the other users as we do in Multiplexing. In reality the concept of Multiple Access is more complicated and In GSM each channel can accommodate 8 users at a time and each channel has 200 KHz bandwidth.Even I am searching its answer. But, I feel, multiplexing is technique and multiple access is way to use this technique.but there is a difference between multiple access and multiplexing that should be noted:Multiple access refers to the remote sharing of a communication channel such as a satellite or radio channel by users in highly dispersed loctions. on the other hand, multiplexing refers to the sharing of a channel such as a telephone channel by users confined to a local site.Modern telephone networks allow bandwidths in their channels that are much larger than those is needed for a digitalized telephone channel. Basically, a number of channels share a common transmission medium with the aim of reducing costs and complexity in the network. Multiplexing is defined as the process by which several signals from different channels share a channel with greater capacity. When the sharing is carried out with respect to a remote resource, such as a satellite, this is referred to as multiple access rather than multiplexing.According to the definition described in Encyclopedia of Britinica : Multiplexing is defined as the sharing of a communications channel through local combining at a common point. In many cases, however, the communications channel must be efficiently shared among many users that are geographically distributed and that sporadically attempt to communicate at random points in time. Three schemes have been devised for efficient sharing of a single channel.
Which modulation technique is used in gsm?
GSM uses GMSK modulation scheme. GPRS also uses GMSK modulation scheme. EDGE and UMTS uses 8-PSK.
What Type of modulation used in GSM?
The modulation used in GSM is Guassian minimum-shift keying (GMSK), a kind of continuous-phase frequency shift keying. In GMSK, the signal to be modulated onto the carrier is first smoothed with a Guassian low-pass filter prior to being fed to a frequency modulator, which greatly reduces the interference to neighboring channels (adjacent channel interference). Added By:Muhammad Kamran Atif Contact: kami_cch@hotmail.com
Why gmsk is used for gsm?
GMSK for GSMGMSK is used in GSM because it provides good spectral efficiency. i think 8-psk modulation is also used..... for edge hardware.Well the reason GMSK is used for GSM.1. High spectral Efficiency2. Since Basic MSK uses Phase variations for modulation so better immune to noise.3.Use of non-linear amplifiers at receivers can be utilized since the information is stored in phase variations rather than amplitude, Non-linear amplifiers give better response and consume less power so low battery usage which is a important parameter in Cellular technology.
What is difference between OFDM - orthogonal frequency division multiplexing and GMSK - gaussian minimum shift keying?
Orthogonal FDM is a method of passing digital data that uses multiple carriers. The basic idea is, you take a high-rate data stream, convert it into a number of low-rate data streams, put each of these streams on a slightly different frequency and dissemble all of it back into the high-rate stream at the distant end. A low-rate stream doesn't require as much bandwidth as a high-rate one does, so you can afford to use multiple frequencies without knocking everyone else off the air. Error correction schema are used to prevent losing data, and monitoring the atmosphere allows the radio to move channels around as necessary to ensure reliability. The reason you want to go through all this trouble is to be able to communicate when atmospherics turn bad. A similar technique is used in tropospheric-scatter radios, which bounce radio waves off part of the upper atmosphere; because the troposphere changes all the time, the only way to reliably communicate via it is to transmit the same data over several different frequencies at once. But in troposcatter, it's called diversity operation. Minimum-shift keying is a form of frequency-shift keying, in which one frequency stands for a 1 - or 'mark' in teleprinter terms - and a different frequency for a 0, or space. This is a technique that's over a century old, and a century ago the way you did it was to wire a small capacitor in series with the contacts on an electromechanical relay, wire that assembly in parallel with the frequency-determining capacitor in your transmitter, and wire the relay's coil to your teleprinter. When the system needed to send a mark, the teleprinter closed the relay which changed the total capacitance of the LC tank which caused the radio's transmitting frequency to change. And they did it this way for at least seventy years! The problem with it (besides needing all those mechanical parts to get the thing to work, and the slow transmitting speeds it required; you certainly wouldn't be able to watch YouTube videos on your phone by keying an oscillator with a relay) is the technique created huge, bandwidth-eating sidebands that didn't matter when the only people sending FSK data were police departments and newspapers, but these days the only people NOT sending FSK data are babies too young to use phones, your grandma who refuses to buy a cell phone, and people in prison who aren't allowed to own cell phones. Today you couldn't get away with eating this much bandwidth, so "minimum-shift keying" - an FSK technique that creates very small sidebands - is the way to go, and feeding the signal through a gaussian filter to create gaussian MSK gives you a very reliable way to transmit data. A good answer to put on your paper might be "OFDM uses multiple carriers and GMSK uses a single carrier."
What is gfsk modulation?
whatbis GMSK MODULATION ?
What Spectral efficiency means related to GMSK in GSM?
0.17 bit/s per Hertz per sector
What has the author Luis E Climaco-Toledo written?
Luis E. Climaco-Toledo has written: 'GMSK data transmission'
What are the Uses of modulation techniques in telecommunication?
In GSM generally GMSK which is a derivative of MSK is beeing used because of its spectral efficiency and more noise resistant. Regards Sumeer Mehaboob
What type of modulation is used in GSM and CDMA?
I think OFDMA is used for cellphone communications via satellites. As far as I know, it is the best technique available which addresses all challenges like multipath fading, error correction, effective bandwidth utilization, security issues etc. Here, harmonics of a base carrier are considered for modulation. These signals will be orthogonal to each other. Hence can be overlapped on each other for transmission, without the signals getting collided. If we use N such orthogonal carriers, the BW requirement will be N times lesser than the classical modulation schemes (such as ASK, BPSK etc.) Practically, using N signal generators to produce precise orthogonal signals is difficult. Hence we do this in digital domain, where IFFT operation performs the same. (producing & adding orthoganal carrier signals). I'm Shreyas. Setting up an OFDM based Tx-Rx model was my academic project during my bachelor studies under Telecommunications. Hope I have answered in a simple way, with enough details :)
What is the different between segmentation and multiplexing?
AnswerMODULATION:Usually, the signal that we want to transmit, say a speech signal with 4000 Hz frequency, will require a very big antenna. For any signal the frequency f is related to wavelength Lasc = L * f ………………………… (i)Where c is velocity of light. And antenna length is generally taken as L/2 which simply means for our case antenna length is 75000 m, obviously this size of antenna is too big to use on day to day basis. That is why we take our speech signal or the desired signal and take another high frequency signal known as carrier (carrier can be any signal but should have high frequency and in practice we use a simple continuous wave signal), now we alter one or more parameters of this career signal in accordance with our desired signal, this parameters can be any one or combination of parameters. The basic parameters are amplitude, frequency, and phase of the signal. The result of this alteration we get is known as modulated signal, the desired signal which we wanted to transmit is known as modulating signal also known as base band signal and modulated signal is also known as band pass signal. The whole process is known as MODULATION.There are many types of modulation starting from amplitude modulation popularly known as AM, frequency modulation (FM), QPSK, PCM, GMSK, QAM etc.MULTIPLEXING:Basically there are two types of system, time domain and frequency domain. In time domain we transmit frames, and in frequency domain we transmit in accordance with frequency. Now if there is more than one source of signal and we want to transmit them together then we implement multiplexing. In multiplexing we mix the source signals (off course with some precautions) say if we want to mix them in time domain then our frame will contain some packets form source A and some packets from source B and so on depending upon the constraints of the channel and time frame. The signals that source are generating can either be modulated signals or we can even send our multiplexed signal to the modulator and then modulate the signal. At the receiving end be demultiplex the signals. In multiplexing we do not provide a dedicated resource to a single source. I.e. we do not dedicate the complete time frame to a single source (in our case it is time frame). Multiplexing is also seen as you are travelling on a four lane road and suddenly it get narrower and turned to single lane, at this point the traffic police will allow one car from each lane to drive through that narrow single lane, this is what we called MULTIPLEXING.MULTIPLE ACCESS:As the name suggest, multiple access means multiple users can access the channel or link. Multiple access provides dedicated resources to the user (with a time constraint) in comparison to the multiplexing which does not provide any type of resources. There are many type of Multiple access schemes like FDMA frequency division multiple access, TDMA time division multiple access, CDMA code division multiple access, SDMA space division multiple access etc. take the example of FDMA, the whole frequency band is divided into small frequency bands called channels, now each channel is having certain capacity to take the traffic say a channel can accommodate single user at time, then the whole frequency bandwidth can be access by as many users as there are channels, mathematically if we are having a bandwidth of 200 KHz and channel bandwidth is 50 KHz then it means we can accommodate 4 users at a time by giving 50 KHz channel to each. This is so called multiple access, i.e. multiple users can access the bandwidth simultaneously and we do not require any additional hardware at the receiving end to separate the desired user from the other users as we do in Multiplexing. In reality the concept of Multiple Access is more complicated and In GSM each channel can accommodate 8 users at a time and each channel has 200 KHz bandwidth.Even I am searching its answer. But, I feel, multiplexing is technique and multiple access is way to use this technique.but there is a difference between multiple access and multiplexing that should be noted:Multiple access refers to the remote sharing of a communication channel such as a satellite or radio channel by users in highly dispersed loctions. on the other hand, multiplexing refers to the sharing of a channel such as a telephone channel by users confined to a local site.Modern telephone networks allow bandwidths in their channels that are much larger than those is needed for a digitalized telephone channel. Basically, a number of channels share a common transmission medium with the aim of reducing costs and complexity in the network. Multiplexing is defined as the process by which several signals from different channels share a channel with greater capacity. When the sharing is carried out with respect to a remote resource, such as a satellite, this is referred to as multiple access rather than multiplexing.According to the definition described in Encyclopedia of Britinica : Multiplexing is defined as the sharing of a communications channel through local combining at a common point. In many cases, however, the communications channel must be efficiently shared among many users that are geographically distributed and that sporadically attempt to communicate at random points in time. Three schemes have been devised for efficient sharing of a single channel.
