I wanna do a challenging project at the end of each course I take in college and am interested in bigger projects with wider scope as well. But I'm unable to come up with good ideas. Where can I find research papers or sites to help me, given my limited knowledge as an undergraduate? I study Electronics & Communication Engg. while I also take courses from CompSci.
If you want to do projects related to your courses, I wouldn't push towards recent literature. It will be specialized and the emphasis will be on new ideas, not on implementation of your course learnings.
Instead I would look at the references in your texts (often older/harder books). They may have harder exercises or have small design projects.
Also, of course, talk to your teachers.
I [want] a challenging project at the end of each course I take
Whoever gave the course probably knows some challenging projects within the course's scope, so ask them first. If they don't know any (perhaps they aren't particularly interested in the course, they are just forced to teach it), then they'll surely know someone that does. Going further afield, you can search for experts in the field, check out their web pages (where projects for students may be listed), and perhaps even email them.