in discussion Homework discussions / Homework Discussions » Good Luck to you all

Hi all:

Good Luck for the final!

Gig'em aggies!

Recent Forum Posts

ECEN661 Student 10 May 2010 06:11

in discussion Homework discussions / Homework Discussions » Good Luck to you all

in discussion Homework discussions / Homework Discussions » Good Luck to you all

Hi all:

Good Luck for the final!

Gig'em aggies!

ECEN661 Student 09 May 2010 03:46

in discussion Homework discussions / Homework Discussions » About the notes from the mid-term

in discussion Homework discussions / Homework Discussions » About the notes from the mid-term

Dr. Narayanan

Could you please upload the notes and HW solutions before the test?

Thank you

ECEN661 Student 08 May 2010 04:10

in discussion Homework discussions / Homework Discussions » About the notes from the mid-term

in discussion Homework discussions / Homework Discussions » About the notes from the mid-term

We are also waiting for the homework solutions. Please upload them, is possible.

ECEN661 Student 08 May 2010 01:29

in discussion Homework discussions / Homework Discussions » About the notes from the mid-term

in discussion Homework discussions / Homework Discussions » About the notes from the mid-term

Dear Prof.Krishna Narayanan

When will you post the notes from mid-term? Thank you very much.

Krishna Narayanan 07 May 2010 02:15

in discussion Homework discussions / Homework Discussions » Project

in discussion Homework discussions / Homework Discussions » Project

It is unlikely. If you want to talk to me about your performance, you can come by on Friday. I think I will do most of the grading only over the weekend or right after the finals.

ECEN661 Student 05 May 2010 22:01

in discussion Homework discussions / Homework Discussions » Project

in discussion Homework discussions / Homework Discussions » Project

Will we get to know our project scores before exam?

ECEN661 Student 03 May 2010 03:47

in discussion Homework discussions / Homework Discussions » Project

in discussion Homework discussions / Homework Discussions » Project

Hi,

How should we upload the m-files to the web? Moreover, should it be up to Tuesday that we turn in our reports?

Krishna Narayanan 03 May 2010 00:34

in discussion Homework discussions / Homework Discussions » Project

in discussion Homework discussions / Homework Discussions » Project

No, there should be no difference in the implementation. However, make sure you compute the branch metric properly as the square of the magnitude of the difference between what you observe at that time instant and what the noiseless output along that branch should be.

ECEN661 Student 02 May 2010 01:53

in discussion Homework discussions / Homework Discussions » Project

in discussion Homework discussions / Homework Discussions » Project

Is there any difference in the implementation of viterbi if the inputs and tap coefficients are complex and not real?

Krishna Narayanan 01 May 2010 13:12

in discussion Homework discussions / Homework Discussions » Project

in discussion Homework discussions / Homework Discussions » Project

The exact expression for the BER with a Viterbi algorithm is quite difficult to compute (there is no closed form expression or even an infinite series that can be numerically computed). However, we can obtain good lower bounds at high SNR. We can also obtain upper bounds. The relative easy bound to compute would be the lower bound based on computing the minimum Euclidean distance error event just like the example I worked out in class for three tap channel. There are some what easy ways to find this using the MATLAB program that you have already written for the Viterbi Algorithm, it is a bit difficult to explain this here.

As for the noise, there is often some confusion among the origin of what we call as noise in our model. This is thermal noise which has nothing to do with the individual paths that the transmitted signals take to get to the receiver. Read the section on thermal noise from Thermal noise and see that this noise occurs in the electronic circuitry at the receiver. So, you will NOT add noise to each path, but only once to the received signals.

ECEN661 Student 27 Apr 2010 19:21

in discussion Homework discussions / Homework Discussions » Project

in discussion Homework discussions / Homework Discussions » Project

What is the difference between the steps 5 and 6 in the task list? Are there two ways of computing BER - with using and without using Montecarlo simulations?

ECEN661 Student 23 Apr 2010 16:58

in discussion Homework discussions / Homework Discussions » Project

in discussion Homework discussions / Homework Discussions » Project

How to check the performance of viterbi algorithm i.e. What is the theoretical expression for Pe vs SNR graph for viterbi algorithm?

Moreover, How is SNR (or Es/No) defined? Do we add noise to each channel (path) seperately or to the sum?

Hi,

We need some office hours, discussing HW 7 before Tuesday . Is it possible for you?

ECEN661 Student 03 Apr 2010 19:46

in discussion Homework discussions / Homework Discussions » Homework 6

in discussion Homework discussions / Homework Discussions » Homework 6

1. In Question no. 4, whats the definition of ISI? More precisely, do we quantify it in terms of power or something ?

ECEN661 Student 31 Mar 2010 17:18

in discussion General technical discussions / General technical questions » SNR-Pe graph useless?

in discussion General technical discussions / General technical questions » SNR-Pe graph useless?

I think that's why figure 4.6-1 is important.

The figure shows us the relaton btw data rate and SNR, given probability error.

So, when we consider SNR-Pe graph for two different schemes,

first find how much energy do we need for acheive the same Pe,

and then compare the data rate given those amount of SNR.

In this manner, one may be better in SNR but worse in Data rate than the other.

The decision what scheme you're going to use is up to you.

ECEN661 Student 26 Mar 2010 09:15

in discussion General technical discussions / General technical questions » SNR-Pe graph useless?

in discussion General technical discussions / General technical questions » SNR-Pe graph useless?

After we learned a lot of

SNR-Pe graph(Eb/No to error probability graph)

for different signaling scheme

the book summarize that

"One can compare them[different signaling scheme]

on the basis of SNR required to achieve a specified

probability of error. However, such a comparison would

**not be very meaningful**, unless it were made on

the basis of some constraint, such as a fixed data rate

of transmission or, equivalently, on the basis of a fixed

bandwidth."

since we didn't talked about such constraints when we introduced

the SNR-Pe graph, are they making such assumption?

if not, how can we make use of it?

besides,

how can we equate data rate and bandwidth?

it make sense, but I don't feel very solid about it.

ECEN661 Student 15 Mar 2010 20:13

in discussion General technical discussions / General technical questions » howto upload image?

in discussion General technical discussions / General technical questions » howto upload image?

Hi David,

I tried Insert Image Wizard and Imageschack.us for picture "URL". Here is an exampleâ€¦

I hope it works.

ECEN661 Student 15 Mar 2010 03:46

in discussion General technical discussions / General technical questions » howto upload image?

in discussion General technical discussions / General technical questions » howto upload image?

how do you guys insert image to this wiki?

I tried "insert image" and "insert image wizard" but failed

insert image need to filled in to the code

`[[image source]]`

but I don't know what should I filled into

and the wizard need URL of the image

I tried my image on picasa

but it takes a long time to upload which I don't know

if it will succeed or not

any ideas?

David

Krishna Narayanan 09 Mar 2010 00:40

in discussion Homework discussions / Homework Discussions » Last Year's Mid Term

in discussion Homework discussions / Homework Discussions » Last Year's Mid Term

In problem 3 you should be able to write the answer in terms of product of Q functions. In Problem 5, you should be able to write the answer as a Q function

Krishna

ECEN661 Student 08 Mar 2010 22:24

in discussion Homework discussions / Homework Discussions » Last Year's Mid Term

in discussion Homework discussions / Homework Discussions » Last Year's Mid Term

In Q3. and Q5., do we leave the probability of error in terms of a double integral?

Unless otherwise stated, the content of this page is licensed under Creative Commons Attribution-ShareAlike 3.0 License