ARQ/HARQ-related procedure for grant-free random access

A wireless communication system, comprising:

• one or more UEs, and
• one or more base stations, BSs,
• wherein the one or more BSs are configured to serve the one or more UEs, wherein certain UEs of the one or more UEs, which are served by the one or more BSs, are configured to perform a transmission to the one or more BSs using a grant-free, GF, transmission scheme, the transmission being performed in accordance with a GF transmission configuration,
• wherein the one or more BSs are configured to receive from the certain UEs respective grant free transmissions and to determine whether the certain UEs can be identified from the respective grant free transmissions,
• wherein in case some or all of the certain UEs cannot be identified by the one or more BSs, the one or more BSs are configured to transmit a certain signaling, the certain signaling indicating that the one or more BSs failed to identify the certain UEs from the transmission, and causing the certain UEs to retransmit the transmission in accordance with a GF retransmission configuration, the GF retransmission configuration being different from the GF transmission configuration,
• wherein the GF transmission configuration comprises a time at which the transmission is performed, and the GF retransmission configuration comprises a plurality of time offsets for the retransmission relative to the time of the transmission,
• wherein the UE is configured to select, based on a UE-ID or on a group or service type, from the plurality of time offsets
• randomly a time offset for the retransmission, or
• a preconfigured time offset for the retransmission, and
• wherein UEs of a certain type use the preconfigured time offset, and other UEs use the random time offset.

A method, comprising:

• performing by a user equipment, UE, of a wireless communication network, which comprises one or more base stations, a grant-free, GF, transmission to at least one base station of the one or more base stations using a GF transmission scheme, the GF transmission being performed in accordance with a GF transmission configuration,
• receiving, at the UE, from the at least one base station a certain signaling, the certain signaling indicating that the at least one base station failed to identify the UE from the GF transmission, and
• responsive to the certain signaling from the at least one base station, retransmitting, by the UE, the GF transmission in accordance with a GF retransmission configuration, the GF retransmission configuration being different from the GF transmission configuration,
• wherein the GF transmission configuration comprises a time at which the transmission is performed, and the GF retransmission configuration comprises a plurality of time offsets for the retransmission relative to the time of the transmission,
• wherein the UE is configured to select, based on a UE-ID or on a group or service type, from the plurality of time offsets
• randomly a time offset for the retransmission, or
• a preconfigured time offset for the retransmission, and
• wherein UEs of a certain type use the preconfigured time offset, and other UEs use the random time offset.

A non-transitory digital storage medium having a computer program stored thereon, wherein the computer program, when run by a computer, performs a method comprising:

• performing by a user equipment, UE, of a wireless communication network, which comprises one or more base stations, a transmission to at least one base station of the one or more base stations using a grant-free, GF, transmission scheme, the transmission being performed in accordance with a GF transmission configuration,
• receiving, at the UE, from the at least one base station a certain signaling, the certain signaling indicating that the at least one base station failed to identify the UE from the transmission, and
• responsive to the certain signaling from the at least one base station, retransmitting, by the UE, the transmission in accordance with a GF retransmission configuration, the GF retransmission configuration being different from the GF transmission configuration,
• wherein the GF transmission configuration comprises a time at which the transmission is performed, and the GF retransmission configuration comprises a plurality of time offsets for the retransmission relative to the time of the transmission,
• wherein the UE is configured to select, based on a UE-ID or on a group or service type, from the plurality of time offsets
• randomly a time offset for the retransmission, or
• a preconfigured time offset for the retransmission, and
• wherein UEs of a certain type use the preconfigured time offset, and other UEs use the random time offset.