Re: Fw: Assig #5 questions

Ed Casas (edc@ece.ubc.ca) Wed, 5 Apr 2000 14:20:25 -0700 

Date: Wed, 5 Apr 2000 14:20:25 -0700
From: Ed Casas <edc@ece.ubc.ca>
Subject: Re: Fw: Assig #5 questions



On Tue, Apr 04, 2000 at 09:42:46PM -0700, Amr Mohamed wrote:

> Once again, I would appreciate if someone can have some answers
> to these questions. I posted them 2 days agi and I haven't
> received any answer so far. Thanks and sorry for inconvenience.
...

> 1-problem 10.8, is spectral efficiency equivalent to bandwidth
> efficiency and not power efficiency?

Yes.

> 2-10.20, I do not seem to get the meaning of "fade slope" in
> db/s. Are we supposed to get the fade as function of time and
> then get the slope or what?

The fade slope is the rate of power change (dB/s).  IS-95 uses a
feedback channel for power control on the reverse channel.  This
channel has a limited data rate and thus can only compensate
fading up to a certain maximum slope.

> 3- 10.24, are we required to figure out the cell coverage for
> AMPS and IS-54, I believe we haven't discussed those standards
> in the class.

We haven't discussed these in detail, but we have discussed TDMA,
CDMA and FDMA (AMPS).  This question is meant to get you to think
about the differences between CDMA (where the interference is
mainly due to users in the same cell) and FDMA/TDMA (interference
is mainly due to users in co-channel cells).  In each case how
will the effective cell radius (the maximum distance where you
can get acceptable service) be affected by the number of users?

> 4- I cannot seem to find a reference in the text book about the
> material we discussed in the last class (link budget). Is there
> any reference other than the class handouts.

No, the text doesn't cover link budgets.  There is a section in
Proakis' book "Digital Communications" and it's also covered in
Haykin's "An Introduction to Analog and Digital Communications."

-- 
Ed Casas   edc@ece.ubc.ca   http://casas.ece.ubc.ca   +1 604 822-2592