Generic CDMA Principles and Techniques

Generic CDMA Principles and Techniques pdf

Code Division Multiple Access (CDMA)
In this case, a radio channel supports a number of simultaneous users who are
separated only by digital coding of their signals, such that the coding of each user’s
signal is as different as possible to every other user’s code. Careful decoding at the
receiver can then separate users. An analogy can be drawn by considering a crowded
restaurant. If many diners are speaking simultaneously, the human ear can “tune” into
one voice by using the unique audio characteristics (“coding”) of the voice. This is
possible if no diner is speaking very loudly or softly, i.e. all are speaking with similar
volume. The listener’s decoding task is made even easier if the speaker of interest
uses a language (e.g. French) different from all others (e.g. English). This is equivalent
in CDMA to a user being given a code very different from all others. CDMA appear to
offer better spectral efficiency than FDM/TDMA – perhaps 4 or 5 times better. Other
benefits will discussed later.

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Understanding UMTS-WCDMA

W-CDMA applied to UMTS PDF

W-CDMA is a multiple access technique using a concept known as Spread Spectrum.
In Spread Spectrum systems, the information bandwidth is “spread” across a wider
transmission bandwidth. This transmission bandwidth is determined by a function
which is independent of the information being sent.
So the information from both simple speech and complex video services, which
clearly have very different “information bandwidth”, will both be converted to be sent
over the full frequency band defined for the system.
Application of the same spreading codes once again at the receiver returns the
transmitted signals back to their original bandwidths.
In order to allow them to be distinguished at a receiver, signals which coexist within
the transmission frequency band must be separated using codes which have a low
cross-correlation with the other codes. In other words decoding signals using the
wrong code will simply produce “noise”, since only the signal with the desired code
will be strongly recognised.
Being able to distinguish signals from different users using codes gives rise to the
term Code Division Multiple Access.

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ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING FOR WIRELESS COMMUNICATIONS- EBOOK

orthogonal frequency division multiplexing for wireless communications pdf

Orthogonal frequency division multiplexing (OFDM) has been shown to be
an effective technique to combat multipath fading in wireless channels. It
has been and is going to be used in various wireless communication systems.
This book gives a comprehensive introduction on the theory and practice of
OFDM for wireless communications.

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L – I – S – T – E – N - I - N - G

Hi Folks,

Came across this lovely article and would like to share it with you all..

In any walk of life, whatever the professiona you practice, if you
are human being, because God gave youthe power of listening,
understanding and responding (orally or written), unlike any other
living being on the planet. Then it becomes vital that we develop
this habit called L – I – S – T – E – N - I - N - G

Poor listening habits account for a large percentage of communication
breakdowns.

To Avoid Communication Breakdown L – I – S – T – E – N ..

How many times have you found yourself saying "You never told me?"

Avoid these bad habits and develop your listening skills. Listening
is a skill that can be improved with practice, practice, and more
practice.

If you want to listen so you really HEAR what others say, make sure
you're not a:

Responder - Rehearser:
You mentally prepare for "Here's what I'll say next" and subsequently
tune out what else is being said.

Evaluator - Judger:
The burden of listening is on the listener. Don't automatically
condemn a speaker or the subject as uninteresting; don't prejudice
your listening because you don't like the speaker's looks, hairdo,
and voice and so on.

Un-Conscious - Daydreamer:
You have that "deer in the headlights look" leading to an
embarrassing "What did you say?" or "Could you repeat that?"

Imposter - Placater:
Agreeing with everything you hear just to be nice or to avoid
conflict does not mean you're a good listener.

Deralier - Changer:
You change the subject so quickly that the speaker believes you're
not interested in what he/she has to say.

Chooser - Selector:
You filter out what you don't what to hear.

Rigid - Defender:
You don't hear all of what someone has to say because a single
comment made by the speaker has upset you.

Actor - Faker:
Don't pretend to be getting the message while your mind has made a
mental detour and is busy with completely different ideas. If the
speaker tries to interact with you at this point, you'll find
yourself completely lost.


If only your listening skills improve you will fidn that the rate at
which your career will "ZOOM" will surprise you too.

Happy L – I – S – T – E – N - I - N - G

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EBOOK-Multicarrier Techniques for 4G Mobile Communications

Multicarrier Techniques for 4G Mobile Communications.pdf

This book provides a comprehensive introduction to multicarrier techniques
including orthogonal frequency division multiplexing (OFDM), putting
much emphasis on the analytical aspects by introducing basic equations
with derivations.

http://www.4shared.com/file/121165363/991b26c8/1580534821-Artech-Multicarrier_Techniques_for_4G_Mobile_Communications.html

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HSDPA/HSUPA for UMTS(ebook)

http://www.4shared.com/file/103288461/6c2e5327/JohnWileyandSonsHSDPAHSUPAforUMTSJun2006.html

Preface:This book was motivated by the fact that HSDPA and HSUPAare the next big steps in
upgrading WCDMA networks. While the WCDMA operation has experienced some
enhancements on top of dedicated channel operation, there was a clear need – it was felt –
to focus just on HSDPA and HSUPA issues without having to repeat what was
already presented in the different editions of WCDMA for UMTS for Release 99
based systems. Also, valuable feedback obtained from different lecturing events on
HSDPA and HSUPA training sessions had clearly indicated a shift in the learning
focus from basic WCDMA to the HSPA area. Thus, this book’s principal task is to
focus on HSPA specifications, optimization, and performance. The presentation concentrates
on the differences that HSPA has brought to WCDMA radio access. Detailed
information about WCDMA radio can be obtained from WCDMA for UMTS.

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