Adaptive Modulation Of 4G wireless communication
4G Communication
I-The Use of Adaptive Modulation Not Fixed Modulation:
The reason is as the Fading channels confront us with the problem
of lost Packets and the need for frequent re-transmissions and
Wireless communication systems are affected by changing weather conditions.
of lost Packets and the need for frequent re-transmissions and
Wireless communication systems are affected by changing weather conditions.
And if those effects not handled correctly, such systems may not be
able to cope with issues such as signal degradation thereby seriously
endangering a Carrier’s ,quality of service obligations.
To overcome this effects making coding and interleaving to reduce
the effect of channel and weather effects but it reduces the
throughput of the channel, but we can “Dynamic Adaptive Modulation”
which ensures maximum bandwidth most of the time with guaranteed
critical services all the time .
able to cope with issues such as signal degradation thereby seriously
endangering a Carrier’s ,quality of service obligations.
To overcome this effects making coding and interleaving to reduce
the effect of channel and weather effects but it reduces the
throughput of the channel, but we can “Dynamic Adaptive Modulation”
which ensures maximum bandwidth most of the time with guaranteed
critical services all the time .
II- Idea of Adaptive Modulation:
The basic idea of Adaptive Modulation is to adapt different
order modulations that allow sending more bits per symbol
and thus achieving higher throughput or better spectral
efficiencies However, it must also be noted that when using
a modulation technique such as 64-QAM, better signal-to-noise
ratios (SNRs) are needed to overcome any interference and
maintain a certain bit error ratio (BER).
The use of adaptive modulation allows a wireless system to
choose the highest order modulation depending on
,the channel conditions then when
*The channel condition is good use 16-QAM or 64-QAM
*Bad channel condition use QPSK
*The channel is very bad do not send the data or use BPSK
In one word we can define Adaptive Modulation as
the automatic modulation adjustment that a wireless system
can make to prevent weather-related fading from causing
communication on the link to be disrupted.
From the figure, knowing the mean of the adaptive modulation
As the channel changes the modulation schemes also changes
(to maintain a constant BER (here its 10^-5
The adaptive modulation try to use the time -variation in
channel conditions to increase the capacity of the system
not try to fight this effects only.
or can be obvious from the following figures that the modulation
scheme changes due to weather changes or the distance form the a
antenna
The Block diagram of adaptive modulation:
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Adaptive Modulation of wireless Communication channel,wireless Communications channel,
4G Communications,Adaptive Modulation of wireless Communications channel
Adaptive Modulation of wireless Communication channel,wireless Communication channel,
Adaptive Modulation of wireless Communications channel,wireless Communications channel,
Adaptive Modulation of wireless Communication channel in 4G communication,wireless Communication channel in 4G communication ,
Adaptive Modulation of wireless Communications channel in 4G communications,wireless Communications channel in 4G communications,
Adaptive Modulation of 4G wireless Communication channel,4G wireless Communication channel,
1 comments:
I have project about adaptive modulation and I'm so excited to see this blog about it ,,,and i'll be more if there is more information about it ...and thanks so much ...... :)))))))))))
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