Data Rate, bandwidth

Hi there,

I have the following question:

1) For each modulation scheme, there is a corresponding bandwidth
efficiency (let's call it n). n = R/B where R is the data rate and B is
the bandwidth. My question is can I simple say R = n*B no matter how big B
is. i.e. can I reach higher data rate by increasing the bandwidth using the
same modulation scheme.

2) If the above equation can not be applied due to each modulation scheme
data rate limit, how can I calculate the data rate given the modulation
scheme, coding and bandwidth? (Assume the certain SINR is good enough)

thanks!!

Yiu

In principle yes.
All of the following
- bit rate
- symbol rate
- bandwidth
- absolute transmitted power
- absolute noise power in the BW assuming AWGN
can scale linearly with the same factor.

A dumb example: Use two / three / x cellphones at the same time. As long
as they can use different radio channels (=more bandwidth), the total
capacity scales linearly.

Needless to say, this is a very simple answer to a question that can get
quite complex, depending on where you're heading.

Cheers

Markus

Thanks Markus.

In general, can I use the bandwidth efficiency for particular modulation
to calculate the data rate given bandwidth? E.g. 8-PSK, the bandwidth
efficiency is 1.5, if bandwidth is 640MHz, will I get 1.5x640Mbps =
960Mbps?

thanks again. really appreciate your help.
Yiu

>In principle yes.
>All of the following
>- bit rate
>- symbol rate
>- bandwidth
>- absolute transmitted power
>- absolute noise power in the BW assuming AWGN
>can scale linearly with the same factor.
>
>A dumb example: Use two / three / x cellphones at the same time. As long
>as they can use different radio channels (=more bandwidth), the total
>capacity scales linearly.
>
>Needless to say, this is a very simple answer to a question that can get
>quite complex, depending on where you're heading.
>
>Cheers
>
>Markus
>

On Mon, 10 Sep 2007 10:24:45 -0500, "blueyiu" <candy@cs.pdx.edu>
wrote:

>Thanks Markus.
>
>In general, can I use the bandwidth efficiency for particular modulation
>to calculate the data rate given bandwidth? E.g. 8-PSK, the bandwidth
>efficiency is 1.5, if bandwidth is 640MHz, will I get 1.5x640Mbps =
>960Mbps?
>
>thanks again. really appreciate your help.
>Yiu

It sounds like you're including an assumed code rate of R = 1/2, since
uncoded 8PSK is really 3 bits per symbol, not 1.5.

For the most part, though, you're correct that data rate scales
linearly with bandwidth for a given modulation order and code rate.

Practical effects like spectrum availability and transmit power tend
to limit things, though.

Eric Jacobsen
Minister of Algorithms
Abineau Communications
http://www.ericjacobsen.org

>On Mon, 10 Sep 2007 10:24:45 -0500, "blueyiu" <candy@cs.pdx.edu>
>wrote:
>
>>Thanks Markus.
>>
>>In general, can I use the bandwidth efficiency for particular modulation
>>to calculate the data rate given bandwidth? E.g. 8-PSK, the bandwidth
>>efficiency is 1.5, if bandwidth is 640MHz, will I get 1.5x640Mbps =
>>960Mbps?
>>
>>thanks again. really appreciate your help.
>>Yiu
>
>It sounds like you're including an assumed code rate of R = 1/2, since
>uncoded 8PSK is really 3 bits per symbol, not 1.5.
>
>For the most part, though, you're correct that data rate scales
>linearly with bandwidth for a given modulation order and code rate.
>
>Practical effects like spectrum availability and transmit power tend
>to limit things, though.
>
>Eric Jacobsen
>Minister of Algorithms
>Abineau Communications
>http://www.ericjacobsen.org
>


Might Yiu are implying a Trellis Coded Modulation?