BLOCK DIAGRAM by F4shxIT

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									     Interference Cancellation and Detection for More than
                          Two Users

ABSTRACT:

In multiple access channels, when users know each other’s channels, precoders can be designed
utilizing channel information to cancel the interference at the receiver without sacrificing the
diversity or the complexity of the system. Recently, it was shown that when there are only two
users,a receiver can completely cancel the interference of the two users and provide full diversity
for each user. Unfortunately, the scheme only works for two users. In this paper, we extend the
scheme to more than 2 users. In other words, we propose a system to achieve interference
cancellation and full diversity with low complexity for any number of users. Then, we extend the
results to any number of users with any number of transmit and receive antennas. Our main idea
is to design precoders, using the channel information, to make it possible for different users to
transmit over orthogonal directions. Then, using the orthogonality of the transmitted signals, the
receiver can separate them and decode the signals independently. We also analytically prove that
our system provides full diversity to each user. Simulation results confirm our analytical proof
and show that our proposed scheme outperforms other existing interference cancellation
schemes.

BLOCK DIAGRAM:



                                                                       ML                User 1
    User 1             Encoder                      Noise           Decoder




    User 2             Encoder                    Channel           ML Decoder           User 2




    User 3             Encoder                                      ML Decoder           User 3
EXISTING SYSTEM:

The existing multi-user systems are the small number of required receive antennas and the low
complexity of the array-processing decoding. However, as mentioned before, full diversity for
each user is only achieved using maximum-likelihood detection. On the other hand, maximum-
likelihood detection is usually not practical, because its complexity increases exponentially as a
function of the number of antennas, the number of users, and the bandwidth efficiency


DISADVANTAGES OF EXISTING SYSTEM:

            High complexity
            High interference
            Limited users


PROPOSED SYSTEM:

Our main idea is to design precoders, using the channel information, to make it possible for
different users to transmit over orthogonal directions. Then, using the orthogonality of the
transmitted signals, the receiver can separate them and decode the signals independently. We
have analytically proved that the system provides full diversity to each user and extended the
results to any number of users each with any number of transmit antennas and one receiver with
any number of receive antennas.


ADVANTAGES OF PROPOSED SYSTEM:

    Full diversity achieved

    High interference cancellation

    It is applied to many no of users

    Low complexity
DOMAIN

COMMUNICATION

        Wireless communication is the transfer of information over a distance without the use of
electrical conductors or "wires". The distances involved may be short (a few meters as in
television remote control) or long (thousands or millions of kilometers for radio
communications). When the context is clear, the term is often shortened to "wireless". Wireless
communication is generally considered to be a branch of telecommunications.


SOFTWARE REQUIREMENT

MATLAB 7.9

MATLAB

MATLAB is a high-performance language for technical computing. It integrates computation,
visualization, and programming in an easy-to-use environment where problems and solutions are
expressed in familiar mathematical notation. Typical uses include:

       Math and computation
       Algorithm development
       Modeling, simulation, and prototyping
       Data analysis, exploration, and visualization
       Scientific and engineering graphics
       Application development, including Graphical User Interface building

MATLAB is an interactive system whose basic data element is an array that does not require
dimensioning. This allows you to solve many technical computing problems, especially those with matrix
and vector formulations, in a fraction of the time it would take to write a program in a scalar non-
interactive language such as C or FORTRAN.

								
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