Question about continuous-channel capacity

[IBO]

HI


Is channel capacity described by number of bits/transmission.

Adding; if i have a channel capacity of 1 bit does that mean that i couldn't use QAM modulation.

thanks

 

[suamol]

Re: Channel capacity

1. Is channel capacity described by number of bits/transmission.

Yes. In other words, you can say bits / dimension pair or 2 times bit / dimension.

2. Adding; if i have a channel capacity of 1 bit does that mean that i couldn't use QAM modulation.

If you have a channel capacity of 0.5 bit / dimension which means you are in high SNR and low bandwidth regime, then you had better not to use any modulation scheme than binary ones such as BPSK. If you use, it is not possible to reduce error probability to zero whatever channel code you use.

Added after 3 minutes:

Let me correct my mistake;

If your channel has a capacity of 0.5 bit / dimension, then you are in low SNR regime not high SNR.

 

[aliazmat]

Re: Channel capacity

Dear thanks for such a nice explaination on the group.

If you could please help me regarding the following statement.
"
For a continuous-channel with bandwidth W Hz available for transmission, the discrete time model contains W two-dimensional symbols per second (2D/s)
"

I dont understand what does "W two-dimensional symbols per second (2D/s)" mean.

I hope you would help me.

 

[irfankundi]

Channel capacity

u cant use QAM for 1 bit. instead u can use BPSK.

 

[suamol]

Re: Channel capacity

If you have a certain SNR on a AWGN channel then you have a capacity of log(1+SNR) bits / transmission.

If the channel has a bandwidth of W, then you can send W transmission / sec.

If you have a certain SNR over a channel with W Hz, then you can get a capacity of W log (1+SNR) bits/sec.

Hope this helps.

 

[hrhgroup]

Re: Channel capacity

Dear friends

please visit this and help me!


Thanks

 

[aliazmat]

Re: Channel capacity

Hi suamol,

Thank you for your reply but dear I dont find the option of "helped me" to press.

and "bits / dimension pair or 2 times bit / dimension"

for the above sentense can we say:

dimension pair implies to using both real and imaginary parts of the channel or modulation techniques

Thanks