I am doing BS Computer Science. I will be starting my final year in August and my CGPA is 3.05. I don't have any research experience yet but I am pretty sure that I want to get a PhD degree.
Will 3-4 months of research experience be enough if I involve in a research project now (considering the 15 December deadline for PhD application)? Or should I apply next year and get more research experience?
Plenty of PhD students go into their program without research experience. I would say that of the PhD students I know who went into their PhD directly from their BS in CS well over half had no previous research experience. Previous research experience can help during the application process but it's not required.
That answers your overt question of "Do I need research experience to get into Grad School?" but let's take a moment to look at some of the implied questions you bring up.
Spending more time researching prior to applying for or attending graduate school can help you make sure that a postgraduate degree is really what you want. You should spend some time figuring out what kind of job you want after you are done with school and seeing what level of education will help you reach that goal. Or, in other words, why do you want to go to grad school? There were be a lot more happy grads students if more of them stopped to consider this question. I found that I while I enjoy research, I hate writing research papers SO MUCH that I couldn't face 5 - 7 years of research papers. I also discovered that for the jobs I wanted a PhD wasn't very useful at this point(and that most jobs I looked at would eventually pay for me to go back and get a PhD).
Spending some time researching prior to applying or attending grad school would also be useful if you felt you needed to improve your application packet. You mention a 3.05 CGPA which is kinda, just 'ok' you know? It's not amazing but it's also not bad enough to prevent you from attending graduate school. It's the kind of CGPA that needs strong extracurricular activities, external projects, great letters of recommendation and strong statements of purpose in order to succeed. How are your letters of recommendation? Do you have a good relationship with any instructors that could write a personalized letter? Were you involved in good extracurriculars(not necessarily CS related, but, rather, extracurriculars where you did something)? Have you taken the GREs? How did they go for you? What schools do you want to do your PhD at? How competitive are these schools? These are the kinds of questions that will strongly effect your chances at getting into graduate school. Time researching could help with some of these - it could get you stronger letters of recommendation, buff up missing or subpar extracurriculars, give you time to study for and retake the GRE.
Finally when you start thinking about a PhD you should consider a couple of things:
If you are not 100% positive(and even if you are) that you want to get a PhD and do all the stuff that comes along with that then you should apply to a program that gets you a Masters degree along the way. This way if things don't turn out the way you want them to you still end up with a very useful piece of paper.
What do you want to research? Just saying 'I want a PhD' is a short road to a shitty PhD experience. What are you willing to spend almost the next decade of your life researching? Who do you want to research with? If you want to study, say, Human Computer Interaction then you should be applying to schools that have those programs and have professors publishing and researching in that field. If you aren't sure what you want to study then, perhaps, more time researching before you apply would be useful - it would give you a chance to get the lay of the land and make some decisions(and possibly connections).
I've already brought this up but it bears repeating. What do you want to do with a PhD? Do you want to research? Do you want to teach? Get this shit locked down before you sign up for anything. So many PhD students go into their degree program because 'I want a PhD' without thinking about the why and the what and a not insignificant amount of them end up never finishing.
PhD programs are for applicants who know and show, all they want to do is research! If the research project you are involved in, right now is extraordinarily productive, then you might get into a PhD program this year itself, given that the PhD would be about the research you are doing right now. You can also start writing review papers or research articles to start building your publication record. Even if it is under progress during the time of application, it still counts.
If all (or most) of these are non-feasible for you for the time being, I'd suggest waiting till next year. That way you'd know better what research you want to pursue for PhD and would have a strong profile too. Chances of admission are higher, if you do it(apply for PhD) next year.
Good luck :)
