1. A method and device for transmitting multi-bit Acknowledgement (ACK)/Negative Acknowledgement (NACK) information are disclosed.

2. The negative acknowledgement message is forwarded to a radio link controller for discarding one or more of the data units.

3. 3 In order to avoid ambiguous acknowledgement or negative acknowledgement (ACK/NAK) and diffusion of cooperation process, cooperative and noncooperative frames are distinguished.

4. Conventional TCP/IP network suffers some problems, such as simplex services, source address spoofing and implosion of negative acknowledgement in multicast, in the course of its development.

5. A method for accounting for the presence of a piggybacked acknowledgement/negative acknowledgement (PAN) field in reporting a received signal quality for a current wireless transmit/receive unit (WTRU) is disclosed.

6. A method of supporting a hybrid automatic repeat and request (HARQ) at a user equipment in a mobile communication system comprises transmitting a first packet to a network (561 ), receiving a reception status signal for the first packet from the network (563), obtaining a negative acknowledgement signal (NACK) by decoding the reception status signal, and receiving supplemental control information indicating that the reception status signal is a positive acknowledgement signal (ACK)(564).