The 5th Edition of Digital Communications by Proakis is structured quite differently from the 4th Edition. There are a number of changes in chapter 2, which has been assigned as reading for Assignment 1. Here are some of the changes I could find:

1. The sections 2.1.1 - 2.1.3 of 4th Edition are missing in the 5th Edition, but it's mostly basic probability that we covered in 646.

2. The 4th Edition has some extra content in section 2.1.4 - Probability Distributions like the examples and some extra mathematics under each random variable. Also, notations differ from the 5th Edition, mainly erfc() is replaced by Q() as Dr. Narayanan pointed out.

3. Section 2.2.3 of 4th Edition on Response of a LTI System to a Random Input Signal is not mentioned separately in the 5th Edition.

4. Section 2.2.5 of 4th Edition gives some notes on Discrete Time Stochastic Signals and Systems, which is not mentioned separately in the 5th Edition. But it is material that we have covered before.

5. Section 2.6 of 5th Edition - Complex Random Variables, is missing in the 4th Edition.

6. Some content from 4th chapter of the 4th Edition is transferred to the 2nd chapter in the 5th Edition:

- 4.1 - Representation of bandpass signals and systems transferred to 2.1. However 2.1 also contains equivalent results for low pass signals and systems. And 4.1 seems to focus a lot more on the mathematics.
- 4.2 - Signal Space representation transferred to 2.2. But 2.2 has some extra notes on bandpass & low pass orthonormal bases and on signal to vector and vector to signal mappings.

7. Section 4.1 of 4th Edition give some extra notes on bandpass linear systems and their response to bandpass linear signals.

8. Section 2.9 of 5th Edition talks about bandpass and low pass random processes. This does not seem to be mentioned in the 4th Edition.

Overall, chapter 2 of the 5th Edition contains some new material not seen in the 4th Edition. But the 4th Edition seems to go more into mathematical details. I have pointed out these changes to the best of my knowledge. If I have overlooked any points, or made any mistakes, please do make the changes in this page. Thank you.

- Hemant Raghavan