The 20-year-old has been out on loan before, spending time with Carlisle and Scunthorpe, he has also been capped by Northern Ireland four times.
Sky Blues' chief executive Tim Fisher told the club's official website: "We are delighted to have Oliver on board.
"Andy Thorn has been tracking him for quite a while and was very keen to bring him to the club and it's great news that we have been able to secure his services until the end of the season ahead of many other clubs."