Once the distance is more than about 100m it becomes more challenging to get full quality over cable. If this part of it was implemented by you, instead of buying an off the shelf solution, you would be getting somewhere. The first step is to find a reason, e.g. to make it work better than the off the shelf solution, in some way. Find a shortcoming, provide a solution.
Using an embedded computer would be one approach. Another area for CCTV is to move to high definition. The Raspberry Pi is cheap yet seems to be suited to video processing. You could use it in an embedded system to provide automatic control of lighting, by changing the illumination as required to suit the camera, so the image is optimum all the time, but power is not wasted. This is "lighting management". So many CCTV systems end up with an image that is so poor that it is difficult to identify people.
Another idea is to use the camera to measure something. This might be based on geometry or color or illumination level. Now that cameras have good stable geometry, and so do displays, it is only the lens that matters. This leads to control systems too. The lighting control is a basic control system. Take it a step further, automatic color balance from the lighting, using some sort of signature. It doesn't have to be new, or not done before, rather that you can demonstrate you can work out how to do it.
Another idea is to make the video stream available on a mobile platform. Maybe that would be tablet or a phone, considering you seem to be interested in Android. Basically a gateway into a phone could be easy with wifi, but how about doing it some other way. Perhaps getting that extra range is the way you want to go. Or increased security, convenience, quality.
Another idea is to think of this as a solution for an underwater camera that is at the end of 300m of cable. The cable has to carry power and controls for the camera down the cable and get the signal back. Solutions are to use something like ADSL on a copper cable (OFDM etc.), FM analogue over a coaxial or twisted pair cable, FM of a pulse stream over fiber, or some other fiber solution like Ethernet, but extended. First step, characterize a cable, and then devise solutions. Note that the cable should have an overall shield, grounded at one end to keep it simple, so it behaves more or less the same in air as underwater. Consider safety aspects of using power over the cable.
The idea is not to invent something unique, but to demonstrate that your capability is suitable for and focused on your degree. Thus it can be completely mundane, but you show how you planned the project, completed it on time, set the goals, solved problems, all that stuff. You could think of it like someone had asked you to do something, just like someone did. The difference is you might not use an "IT solution" of buying boxes that plug together for all of the project, but do some part of it from scratch. Engineering is about project management as much as about design, and not so much about "creating original works". e.g. Make a good power supply that has something better than average like high efficiency with light loads, (low standby power, go for 100mW or whatever. Yet how many power supplies are on the market? Billions.