Multi-hop wireless relay communication system and downlink data transmitting method and device

A multi-hop wireless relay system, comprising a base station (BS) and more than one relay station (RS), wherein

• the BS is adapted to obtain a next hop relay station identifier (RSID) corresponding to a connection ID (CID) in a downlink medium access control protocol data unit (MPDU) according to an existing corresponding relationship of the CID and the next hop RSID, and send the downlink MPDU to the next hop RS according to the obtained next hop RSID;
• and
• the RS is adapted to obtain a next hop RSID corresponding to a CID in a received downlink MPDU header according to the existing corresponding relationship of the CID and the next hop RSID, and send the downlink MPDU to the next hop RS till a user terminal according to the obtained next hop RSID.

A communication device, applied to a multi-hop wireless relay system, the communication device is a base station (BS) or a relay station (RS), comprising:

• a routing device, adapted to obtain an identifier (ID) of a next hop network unit corresponding to a connection ID (CID) in a downlink medium access control protocol data unit (MPDU) header according to an existing corresponding relationship of the CID and a path ID, and send the downlink MPDU to the next hop network unit by utilizing the obtained ID of the next hop network unit.