ECE 461 - Spring 2022
Course description: Reliable communication of one bit of information over three types of channels: additive Gaussian noise, wireline, and wireless. Emphasis on the impact of bandwidth and power on the data rate and reliability, using discrete-time models. Technological examples used as case studies, like 2G, 3G, 4G and 5G. Full description, including course goals and instructional objectives, can be found here.
Lectures: TR, 9.30am-10.50am.
- 3013 Electrical & Computer Eng Bldg.
- IMPORTANT: please note that the first week of classes will be fully online, so lectures will by attended using this link, with passwd: ece461here.
- Students MUST properly wear a face mask in order to attend the in-person lectures. Visit the University's COVID-19 website here for detailed information on COVID related procedures.
- Lecture recordings available in Mediaspace.
Prof. Juan Alvarez, alvarez@,
3046 Electrical & Computer Eng Bldg (ECEB), 300-5452.
Dufei Wu, dufeiwu2@
Policy: We invite relevant questions and comments during
lectures. Address your questions and comments to the entire class;
avoid disruptive behavior such as talking to neighbors, unless the
instructor invites you to form discussion groups. Kindly turn off or mute
cell phones, laptop computers, and other electronic devices during
Introduction to Communication Systems, Madhow.
J. G. Proakis and M. Salehi, Fundamentals of Communication Systems, 2nd edition, Prentice-Hall, ISBN: 978-0133354850.
B. P. Lathi and Z. Ding, Modern Digital and Analog Communication Systems, Fifth edition, Oxford University Press, ISBN: 978-0-19-068684-0.
- Lecture Notes on Digital Communication, Viswanath: pdf. Hardcopy available from the ECE Copy Room.
- Supplemental notes:
Prerequisite: The basic prerequisites are a probability course (such as ECE 313 or STAT 410) and some basic signal processing background (such as ECE 210).
Back to top
Communication Systems are the basic workhorses behind the information
age. Examples include high speed communication networks, wireless and
wireline telephone systems, high speed modems, etc. The basic
currency of information is digital: bits . Broadly
speaking, this course is centered around a single theme:
reliably communicate bits over an unreliable physical
medium. The emphasis
is on how to transfer this currency between a
transmitter-receiver pair. The transfer involves a physical
medium, whose input-output characteristics are not deterministically
known. The curriculum has three broad parts:
These three parts are discussed in the course in the context of three
specific physical media:
- Channel Model : Even though the input-output relationship
of the physical medium is not deterministically known,
statistical quantities of this relationship, such as mean and
correlation, can be physically measured and are typically constant
over the time-scale of communication.
- Transmission and Reception Strategies : The statistical
model of the physical medium is then brought into bearing in the
engineering design of appropriate transmission and reception
strategies (modulation and demodulation, in the language of this
- Design Resources and Performance : The resources available
to the communication engineer are power and
bandwidth . The final part of the course is to
relate the statistical performance of the communication strategies
to these two key resources.
- Additive white Gaussian noise channel: The received signal
is the transmit signal plus a statistically independent
signal. This is a basic
model that underlies the more complicated wireline and wireless
- Telephone channel: The received signal is the transmit
signal passed through a time-invariant, causal filter plus
statistically independent noise. Voiceband v.90 modem and DSL
technologies are used as examples.
- Wireless channel: The received signal is the transmit
signal passed through a time-varying filter plus statistically
independent noise. 2G, 3G, 4G and 5G standards are used as
Back to top
Office hours (starting January 24 through May 4):
- Mondays, 1.30-2.30pm, Prof. Alvarez, in ECEB 2036.
- Tuesdays, 1.30-2.30pm, Prof. Alvarez, in ECEB 2036.
- Tuesdays, 4-5pm, Dufei Wu, dufeiwu2@, via Zoom. passwd: ece461here
back to top
Exams scheduled for these dates:
- Exam 1, Thursday, February 24, 9.30-10:50am, in the usual lecture room.
- Exam 2, Thursday, April 7, 9.30-10:50am, in the usual lecture room.
- Final Exam, Thursday, May 12, 1:30-4:30 p.m, 3013 ECEB.
with documented disabilities must notify the lecture instructor at
least two weeks before Exam 1.
- Closed book: all exams will be closed book, closed notes, but you may bring a one-sided 8 1/2 ′′ by 11 ′′ sheet of notes.
However, you should not depend on it, browsing and searching through it will only waste your time. If you know what you are doing, you should not need any aides.
- Calculations: Calculators and other electronic ways to do calculations are not allowed.
Absences from exams:
If you miss an exam due to illness, injury, family emergency or other reasons beyond your control, you will be asked to provide your professor with an absence letter from the Student Assistance Center in the Office of the Dean of Students. Documentation which validates the absence is required by the Dean's Office to provide the absence letter. The absence letter will serve to verify the reason for your absence from the exam. Prof. ALvarez will then take an appropriate action that may include offering an oral examination or written examination.
- We will use Gradescope to grade the exams, so you will receive an email from Gradescope to log in and see your graded exam. If after looking at the posted solutions, you feel there was an inaccuracy in the grading of your exam, you can request a regrade within Gradescope itself.
- Do not submit a regrade asking for more partial credit because you did so much work nor because you think something should be worth more/less that it does. Only regrades regarding inaccurate grading will be addressed.
- Regrades could be subjected a regrading of the entire exam, no just those parts you indicate. Therefore, your grade could go up or down as appropriate.
- You will get an email from the instructors after the exams are graded indicating when you can start submitting regrades and when the deadline to submit the regrades is.
- Make sure you submit regrade requests by the deadline indicated in that email, so do not wait until the last minute to submit it and then run into internet issues.
You can find copies of some old exams and their solutions below.
- These past exams are provided here so you can identify your misconceptions on course topics and get help on those during office hours. They are not a replacement for attending lectures and reading the textbook.
- We provide both the blank exam and the solutions so that you can follow this procedure:
- Solve the blank exam.
- Compare your solutions to the provided solutions and identify your misconceptions.
- If you first look at the solutions and then solve the blank exam, you will not be able to identify your misconceptions as easily, so that is not a good idea.
- Only looking at the solutions without even trying to solve the problems will be of little/no use.
- Solving multiple past exams without understanding the concepts will not result in a good exam grade.
- These exams are a sample of the type of questions that aim at testing the students’ understanding of the course’s concepts, but there are a myriad of other questions, with the same level of difficulty, that could also test those concepts . You should not expect your exam to include questions like those in these past exams.
back to top
It is the student's
responsibility to check that the correct grades are entered in
The final grade will be calculated as follows:
- Class participation/attendance: 10%
- Homework: 20%
- Exam 1: 20%
- Exam 2: 20%
- Final exam: 30%
back to top
Homework assignment policy:
- Assignments will be posted every Wednesday in Gradescope at 9am CST and will be due the following Wednesday by 9am CST.
The first homework will be posted on Wednesday, January 19 and will be due the following Wednesday, January 26 by 9am.
- Submissions will be made via Gradescope. You can join the course there with the entry code 6P3R88, use your UIN as your Student ID #.
- Instructions for uploading your solutions to Gradescope can be found here.
- Instructions on how to scan the pdf of the solutions in Android are here.
- Instructions on how to scan the pdf of the solutions in MacOS are here.
- Late assignments will be deducted 1% per late minute, so after 100 minutes, you will get zero, so please mark your calendar with the deadlines to avoid losing points.
No exceptions, so don't wait until the last minute to submit it and then run into internet issues.
- Solutions will be posted in Canvas 2 hours after the corresponding deadline.
- In order to account for sickness, travel or internet issues, your two lowest assignment grades will be dropped.
- Make sure you box your final answers and match problem parts accurately in Gradescope, or you will be deducted 5% of the corresponding problem part.
- Make sure that your assignments are neat enough to read. Graders has the flexibility to deduct points for lack of neatness.
- Assignments constitute an essential component of your learning experience in the course and prepare you for your exams in effective ways. Investing time to do your assignments with care will pay off when you are taking your exams.
You will be expected to provide detailed explanations of your solutions in order to obtain full credit in your assignments. Conversely, solutions lacking full explanations will receive zero credit even when the answer provided may be correct and further incorrect answers without any work shown may lead to 'academic integrity violation' cases being opened against you.
You are encouraged to collaborate to understand the problems in the assignment, but each student should solve the problems individually for submission even if they work together initially to understand how to solve the problems. Copying a joint solution is not acceptable.
The same applies to using external resources: each student should solve the problems individually for submission even if you use external resources to understand how to solve the problems. Copying or "following" the solutions from an external resource is not acceptable.
Please keep these cautionary remarks in mind as you are working out your assignments and avoid submitting unsubstantiated solutions to avoid any misinterpretations as explained above.
Any of these academic integrity violations will result in at least a letter grade reduction, and possibly stronger sanctions. It is not worth the risk for what each problem in 14 HWs is worth, and it will not help you learn the course material.
- Regrades: You will receive an email from Gradescope so you can log in and see your graded assignment. If after looking at the posted solutions, you feel there was an inaccuracy in the grading of your assignment, you can request a regrade within Gradescope itself.
Make sure you submit regrade requests before 9am CST the Wednesday after your graded assignment is made available via Gradescope. Regrades will not be accepted after that date.
back to top
The University of Illinois at Urbana-Champaign Student Code should is very important for you to know.
Students should pay particular attention to Article 1, Part 4: Academic Integrity.
Academic dishonesty may result in a failing grade. Every student is expected to review and abide by the Academic Integrity Policy.
Ignorance is not an excuse for any academic dishonesty. It is your responsibility to read this policy to avoid any misunderstanding.
Do not hesitate to ask the instructor(s) if you are ever in doubt about what constitutes plagiarism, cheating, or any other breach of academic integrity.
The effectiveness of this course is dependent upon the creation of an encouraging and safe classroom environment. Exclusionary, offensive or harmful speech (such as racism, sexism, homophobia, transphobia, etc.) will not be tolerated and in some cases subject to University harassment procedures. We are all responsible for creating a positive and safe environment that allows all students equal respect and comfort. I expect each of you to help establish and maintain and environment where you and your peers can contribute without fear of ridicule or intolerant or offensive language.
Disability Resources and Educational Services (DRES)
Students with documented disabilities must notify the instructor within the first 7 days of classes.
To obtain disability-related academic adjustments and/or auxiliary aids, students with disabilities must contact the course instructor and the Disability Resources and Educational Services (DRES) as soon as possible.
To contact DRES, you may visit 1207 S. Oak St., Champaign, call 333-4603, e-mail firstname.lastname@example.org or go to the DRES website.
If you are concerned you have a disability-related condition that is impacting your academic progress, there are academic screening appointments available on campus that can help diagnosis a previously undiagnosed disability by visiting the DRES website and selecting “Sign-Up for an Academic Screening” at the bottom of the page.
Any student who has suppressed their directory information pursuant to Family Educational Rights and Privacy Act (FERPA) should self-identify to the instructor to ensure protection of the privacy of their attendance in this course. Click here for more information on FERPA.
The University of Illinois is committed to combating sexual misconduct. Faculty and staff members are required to report any instances of sexual misconduct to the University’s Title IX and Disability Office. In turn, an individual with the Title IX and Disability Office will provide information about rights and options, including accommodations, support services, the campus disciplinary process, and law enforcement options. A list of the designated University employees who, as counselors, confidential advisors, and medical professionals, do not have this reporting responsibility and can maintain confidentiality, can be found here. Other information about resources and reporting is available here.
Support Resources and Supporting Fellow Students in Distress
As members of the Illinois community, we each have a responsibility to express care and concern for one another. If you come across a classmate whose behavior concerns you, whether in regards to their well-being or yours, we encourage you to refer this behavior to the Student Assistance Center (1-217-333-0050) or online. Based upon your report, staff in the Student Assistance Center reaches out to students to make sure they have the support they need to be healthy and safe. Further, as a Community of Care, we want to support you in your overall wellness. We know that students sometimes face challenges that can impact academic performance (examples include mental health concerns, food insecurity, homelessness, personal emergencies). Should you find that you are managing such a challenge and that it is interfering with your coursework, you are encouraged to contact the Student Assistance Center (SAC)in the Office of the Dean of Students for support and referrals to campus and/or community resources. The SAC has a Dean on Duty available to see students who walk in, call, or email the office during business hours. For mental health emergencies, you can call 911 or contact the Counseling Center.
Run, hide, fight.
Emergencies can happen anywhere and at any time. It is important that we take a minute to prepare for a situation in which our safety or even our lives could depend on our ability to react quickly. When we’re faced with almost any kind of emergency – like severe weather or if someone is trying to hurt you – we have three options: Run, hide or fight.
Run, hide, fight video.
Leaving the area quickly is the best option if it is safe to do so.
- Take time now to learn the different ways to leave your building.
- Leave personal items behind.
- Assist those who need help, but consider whether doing so puts yourself at risk.
- Alert authorities of the emergency when it is safe to do so.
When you can’t or don’t want to run, take shelter indoors.
- Take time now to learn different ways to seek shelter in your building.
- If severe weather is imminent, go to the nearest indoor storm refuge area.
- If someone is trying to hurt you and you can’t evacuate, get to a place
where you can’t be seen, lock or barricade your area if possible,
silence your phone, don’t make any noise and don’t come out until you
receive an Illini-Alert indicating it is safe to do so.
As a last resort, you may need to fight to increase your chances of survival.
- Think about what kind of common items are in your area which you
can use to defend yourself.
- Team up with others to fight if the situation allows.
- Mentally prepare yourself – you may be in a fight for your life
Please be aware of people with disabilities who may need additional assistance in emergency situations
- police.illinois.edu/safe for more information on how to prepare for emergencies, including
how to run, hide or fight and building floor plans that can show you safe areas.
- emergency.illinois.edu to sign up for Illini-Alert text messages.
- Follow the University of Illinois Police Department on Twitter and Facebook to get regular
updates about campus safety.