An acknowledgement information feedback apparatus, method and a communication system. The method includes: generating an acknowledgement response vector according to whether data transmitted by a plurality of UEs based on contention are correctly demodulated; generating a measurement vector according to a predetermined compressed sensing measurement matrix and the generated acknowledgement response vector; and broadcasting the measurement vector to the plurality of UEs. The UE recovers the acknowledgement response vector according to a compressed sensing measurement matrix and the measurement vector, and determines whether the transmitted data are correctly demodulated according to the recovered acknowledgement response vector. Hence, it is not only applicable to contention-based data transmission scenarios, but also has relatively low signaling overhead and reliable performance.