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Figure 1 highlights three major performance categories in terms of bit-error probability P B size 12{P rSub { size 8{B} } } {} versus E b / N 0 size 12{E rSub { size 8{b} } /N rSub { size 8{0} } } {}

The leftmost exponentially shaped curve highlights the performance that can be expected when using any nominal modulation scheme in AWGN interference. Observe that at a reasonable E b / N 0 size 12{ {E rSub { size 8{b} } } slash {N rSub { size 8{0} } } } {} level, good performance can be expected.

The middle curve, referred to as the Rayleigh limit , shows the performance degradation resulting from a loss in E b / N 0 size 12{ {E rSub { size 8{b} } } slash {N rSub { size 8{0} } } } {} that is characteristic of flat fading or slow fading when there is no line-of-sight signal component present. The curve is a function of the reciprocal of E b / N 0 size 12{ {E rSub { size 8{b} } } slash {N rSub { size 8{0} } } } {} , so for practical values of E b / N 0 size 12{ {E rSub { size 8{b} } } slash {N rSub { size 8{0} } } } {} , performance will generally be “bad.”

The curve that reaches an irreducible error-rate level, sometimes called an error floor , represents “awful” performance, where the bit-error probability can level off at values nearly equal to 0.5. This shows the severe performance degrading effects that are possible with frequency-selective fading or fast fading.

If the channel introduces signal distortion as a result of fading, the system performance can exhibit an irreducible error rate at a level higher than the desired error rate. In such cases, the only approach available for improving performance is to use some forms of mitigation to remove or reduce the signal distortion.

The mitigation method depends on whether the distortion is caused by frequency-selective fading or fast fading. Once the signal distortion has been mitigated, the P B size 12{P rSub { size 8{B} } } {} versus E b / N 0 size 12{ {E rSub { size 8{b} } } slash {N rSub { size 8{0} } } } {} performance can transition from the “awful” category to the merely “bad” Rayleigh-limit curve.

Next, it is possible to further ameliorate the effects of fading and strive to approach AWGN system performance by using some form of diversity to provide the receiver with a collection of uncorrelated replicas of the signal, and by using a powerful error-correction code.

Figure 2 lists several mitigation techniques for combating the effects of both signal distortion and loss in SNR. The mitigation approaches to be used when designing a system should be considered in two basic steps:

1) choose the type of mitigation to reduce or remove any distortion degradation;

2) choose a diversity type that can best approach AWGN system performance.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
nanopartical of organic/inorganic / physical chemistry , pdf / thesis / review
Ali
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
hey
Giriraj
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
ya I also want to know the raman spectra
Bhagvanji
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
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Source:  OpenStax, Principles of digital communications. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10805/1.1
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