Poster

Channel Capacity (finished)

Today, we have finish the Firgure of Channel Capacity which is shown below;

As the figure shows, there are four lines about the different channel capacities. Next step, we are going to work out which BER of unipolar NRZ and bioplar NRZ are more effective in AWGN channel or fading channel.

Channel Capacity (Unfinished with simulation )

According to the concepts, we know that in the presence of noise, if the number of signal levels M increases, the ability of the receiever to distinguish between symbols decreaes. Hence, we should try to find an appropriate channel to achieve the mitigation of the noise.

There are some channels which are normal to be used in the communication system. AWGN channel and Rayleigh Fading Channel. When we are doing some calculations, the Shannon's Theorem is strongly recommended.

In this experiment, we should find the lower and upper AWGN channel capacity bound and the approximate capacity, then find the numerically computed shannon capacity.

Shannon capacity upper and lower bound are shown in the following formulas, respectively 

At the end of the today's experiment, we havn't simulated all results, so the final figure will be posted in the next blog.

 

The Rayleigh Flat Fading Channel

The Rayleigh Flat Fading Channel can be expressed as following

Shannon capacity equation: 

The AWGN Channel

The AWGN Channel, the model can be expressed as following Figure.

 Vt=Ut+Nt

   Vt:  the channel output

   Ut:  the channel input

   Nt: AWGN random variable with mean zero and variance N0

The Shannon capacity equation:        C=B log2(1+S/N)

Three simulations as the project goes so far.

As we mentioned before, we've already make the Unipolar NRZ in AWGN channel, the figure below is the Bioplar NRZ in AWGN channel;

SUMMARY: As these two figures shows, we can know that the BER of binary bipolar NRZ signal is smaller than the unipolar both in AWGN channel.

Additionally, we make a graph to compare the fading channel and AWGN channel which shown below,

SUMMARY: As the figure shows, the capacity of the AWGN channel is higer than the Fading channel and it is always at the top of the Fading channel.

Some concepts in the project------A SUMMARY

Summary:
1.Channel capacity is limited by the combined effects of channel bandwidth and noise.
2. Hartley' s law (for noiseless channel) 

3.Shannon capacity (for AWNG channel)
 
The reliable communication: R≤C, E_b/N₀≥-1.6dB