An apparatus and method for buffering data in a communication system. The apparatus includes a first and a second storage unit. The first storage unit is configured to store first data in a first mode and retrieve the first data in a second mode. The second storage unit is configured to store second data in the second mode and retrieve the second data in the first mode. The apparatus also has a management logic circuit controlling the first and the second storage units to operate between the first and the second modes. In addition, the management logic circuit performs a collision process if a collision has been detected during a collision detection period.