System and method for pilot assisted grant-free uplink transmission identification

A base station comprising:

• at least one antenna;
• a memory;
• and
• a grant-free transmission module;
• the at least one antenna configured to receive a grant-free uplink transmission on an uplink channel, the grant-free uplink transmission carrying initial data from a user equipment and an initial pilot for channel estimation of the uplink channel;
• the grant-free transmission module configured to attempt to decode the initial pilot and the initial data, and when the initial pilot is successfully decoded and the initial data is unsuccessfully decoded, then the grant-free transmission module is further configured to store in the memory the successfully decoded initial pilot and the unsuccessfully decoded initial data;
• the at least one antenna further configured to receive another grant-free uplink transmission carrying retransmission data from the user equipment and a retransmission pilot used for uplink channel estimation;
• the grant-free transmission module further configured to attempt to decode the retransmission pilot, and when the retransmission pilot is successfully decoded the grant-free transmission module is further configured to:
• use the successfully decoded retransmission pilot to identify the successfully decoded initial pilot in the memory and the unsuccessfully decoded initial data associated with the successfully decoded initial pilot;
• retrieve the unsuccessfully decoded initial data from the memory;
• use the retransmission data and the unsuccessfully decoded initial data to successfully decode the initial data.

A method performed by a user equipment comprising:

• transmitting a grant-free uplink transmission on an uplink channel, the grant-free uplink transmission carrying initial data and an initial pilot to be used for channel estimation of the uplink channel;
• selecting a retransmission pilot usable for uplink channel estimation and associated with the initial pilot such that the initial pilot can be identified from the retransmission pilot;
• and
• transmitting a subsequent grant-free uplink transmission carrying retransmission data and the retransmission pilot.

A user equipment comprising:

• at least one antenna;
• a grant-free transmission module;
• the at least one antenna configured to transmit a grant-free uplink transmission on an uplink channel, the grant-free uplink transmission carrying initial data and an initial pilot to be used for channel estimation of the uplink channel;
• the grant-free transmission module configured to select a retransmission pilot usable for uplink channel estimation and associated with the initial pilot such that the initial pilot can be identified from the retransmission pilot;
• and
• the at least one antenna configured to transmit a subsequent grant-free uplink transmission carrying retransmission data and the retransmission pilot.