# US 2017/0290052 A1 · System and method for pilot assisted grant-free uplink transmission identification > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2017/0290052 A1 - Document ID: US20170290052A1 - Status: Published application - Kind: A1 - Application number: 15/088,607 - Filed: 2016-04-01 - Published: 2017-10-05 - Earliest claimed: 2016-04-01 - Assignees: Huawei Technologies Co., Ltd. - Inventors: LIQING ZHANG; YU CAO - Web page: https://patentgrep.com/patent/US20170290052A1 ## CPC - H04W 74/004: {in the uplink, i.e. towards network} - H04L 1/1896: {ARQ related signaling} - H04J 11/004: {using regenerative subtractive interference cancellation} - H04L 1/1812: Hybrid protocols; Hybrid automatic repeat request [HARQ] - H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72) - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) - H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S) ## Abstract System and methods are disclosed in which pilots are used to assist in identifying grant-free uplink transmissions originating from the same UE. In one embodiment, a base station receives a grant-free uplink transmission that carries initial data from a user equipment and an initial pilot. The initial pilot is successfully decoded and the initial data is unsuccessfully decoded. The successfully decoded initial pilot and the unsuccessfully decoded initial data are stored in memory. Another grant-free uplink transmission carrying retransmission data from the user equipment and a retransmission pilot is then received. The retransmission pilot is successfully decoded and used to identify the successfully decoded initial pilot in the memory and the unsuccessfully decoded initial data. The retransmission data and the unsuccessfully decoded initial data are used to successfully decode the initial data. ## Claims ### Claim 1 A method performed by a base station comprising: receiving 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; successfully decoding the initial pilot and unsuccessfully decoding the initial data; storing in memory the successfully decoded initial pilot and the unsuccessfully decoded initial data; receiving another grant-free uplink transmission carrying retransmission data from the user equipment and a retransmission pilot used for uplink channel estimation; successfully decoding the retransmission pilot; using 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; retrieving the unsuccessfully decoded initial data from the memory; using the retransmission data and the unsuccessfully decoded initial data to successfully decode the initial data. ### Claim 2 (depends on 1) The method of claim 1, wherein using the successfully decoded retransmission pilot to identify the successfully decoded initial pilot comprises: using a mapping, known by the base station, between the successfully decoded retransmission pilot and the successfully decoded initial pilot to identify the successfully decoded initial pilot. ### Claim 3 (depends on 2) The method of claim 2, wherein: the initial pilot is from a set of initial transmission pilots; the retransmission pilot is from a set of retransmission pilots; mapping information between the set of initial transmission pilots and the set of retransmission pilots is known by the base station, the mapping information comprising, for each pilot in the set of initial transmission pilots, a mapping between the pilot in the set of initial transmission pilots and a pilot in the set of retransmission pilots; and the mapping information includes the mapping between the successfully decoded retransmission pilot and the successfully decoded initial pilot. ### Claim 4 (depends on 3) The method of claim 3, wherein the number of unique pilots in the set of initial transmission pilots exceeds the number of unique pilots in the set of retransmission pilots. ### Claim 5 (depends on 1) The method of claim 1, further comprising unsuccessfully decoding the retransmission data; and wherein using the retransmission data and the unsuccessfully decoded initial data to successfully decode the initial data comprises: soft combining the unsuccessfully decoded retransmission data and the unsuccessfully decoded initial data. ### Claim 6 (depends on 5) The method of claim 5, wherein the user equipment is a first user equipment, and the method further comprises: receiving at least one other grant-free uplink transmission from at least one other user equipment, the at least one other grant-free uplink transmission using resources that are the same as resources used by the grant-free uplink transmission of the first user equipment; using the successfully decoded initial data to perform successive interference cancellation (SIC) to assist in decoding data of the at least one other grant-free uplink transmission. ### Claim 7 (depends on 1) The method of claim 1, wherein the initial data has a first modulation and coding scheme (MCS) that is associated with the initial pilot, and the retransmission data has a second MCS that is associated with the retransmission pilot. ### Claim 8 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. ### Claim 9 (depends on 8) The base station of claim 8, wherein the grant-free transmission module is configured to use the successfully decoded retransmission pilot to identify the successfully decoded initial pilot by: using a mapping, known by the base station, between the successfully decoded retransmission pilot and the successfully decoded initial pilot to identify the successfully decoded initial pilot. ### Claim 10 (depends on 9) The base station of claim 9, wherein: the initial pilot is from a set of initial transmission pilots; the retransmission pilot is from a set of retransmission pilots; mapping information between the set of initial transmission pilots and the set of retransmission pilots is known by the base station, the mapping information comprising, for each pilot in the set of initial transmission pilots, a mapping between the pilot in the set of initial transmission pilots and a pilot in the set of retransmission pilots; and the mapping information includes the mapping between the successfully decoded retransmission pilot and the successfully decoded initial pilot. ### Claim 11 (depends on 10) The base station of claim 10, wherein the number of unique pilots in the set of initial transmission pilots exceeds the number of unique pilots in the set of retransmission pilots. ### Claim 12 (depends on 8) The base station of claim 8, wherein the grant-free transmission module is configured to use the retransmission data and the unsuccessfully decoded initial data to successfully decode the initial data by: soft combining unsuccessfully decoded retransmission data and the unsuccessfully decoded initial data, when the retransmission data is unsuccessfully decoded. ### Claim 13 (depends on 12) The base station of claim 12, wherein the user equipment is a first user equipment, and wherein: the at least one antenna is configured to receive at least one other grant-free uplink transmission from at least one other user equipment, the at least one other grant-free uplink transmission using resources that are the same as resources used by the grant-free uplink transmission of the first user equipment; the grant-free transmission module is configured to use the successfully decoded initial data to perform successive interference cancellation (SIC) to assist in decoding data of the at least one other grant-free uplink transmission. ### Claim 14 (depends on 8) The base station of claim 8, wherein the initial data has a first modulation and coding scheme (MCS) that is associated with the initial pilot, and the retransmission data has a second MCS that is associated with the retransmission pilot. ### Claim 15 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. ### Claim 16 (depends on 15) The method of claim 15, wherein: selecting the retransmission pilot and transmitting the subsequent grant-free uplink transmission is performed in response to not receiving an acknowledgement within a predetermined duration of time after transmitting the grant-free uplink transmission carrying the initial data, the acknowledgement indicating that the initial data has been successfully decoded; and selecting the retransmission pilot comprises using a mapping, known by the user equipment, between the initial pilot and the retransmission pilot to identify the retransmission pilot. ### Claim 17 (depends on 16) The method of claim 16, wherein: the initial pilot is from a set of initial transmission pilots; the retransmission pilot is from a set of retransmission pilots; mapping information between the set of initial transmission pilots and the set of retransmission pilots is known by the user equipment, the mapping information comprising, for each pilot in the set of initial transmission pilots, a mapping between the pilot in the set of initial transmission pilots and a pilot in the set of retransmission pilots; and the mapping information includes the mapping between the initial pilot and the retransmission pilot. ### Claim 18 (depends on 17) The method of claim 17, further comprising: receiving the mapping information from the base station. ### Claim 19 (depends on 17) The method of claim 17, wherein the number of unique pilots in the set of initial transmission pilots exceeds the number of unique pilots in the set of retransmission pilots. ### Claim 20 (depends on 16) The method of claim 16 further comprising: waiting for a duration of a back-off window before transmitting the subsequent grant-free uplink transmission. ### Claim 21 (depends on 16) The method of claim 16, wherein the initial data has a first modulation and coding scheme (MCS) that is associated with the initial pilot, and the retransmission data has a second MCS that is associated with the retransmission pilot. ### Claim 22 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. ### Claim 23 (depends on 22) The user equipment of claim 22, wherein: the grant-free transmission module is configured to select the retransmission pilot and the at least one antenna is configured to transmit the subsequent grant-free uplink transmission in response to the user equipment not receiving an acknowledgement within a predetermined duration of time after transmitting the grant-free uplink transmission carrying the initial data, the acknowledgement indicating that the initial data has been successfully decoded; and the grant-free transmission module is configured to select the retransmission pilot by using a mapping, known by the user equipment, between the initial pilot and the retransmission pilot to identify the retransmission pilot. ### Claim 24 (depends on 23) The user equipment of claim 23, wherein: the initial pilot is from a set of initial transmission pilots; the retransmission pilot is from a set of retransmission pilots; mapping information between the set of initial transmission pilots and the set of retransmission pilots is known by the user equipment, the mapping information comprising, for each pilot in the set of initial transmission pilots, a mapping between the pilot in the set of initial transmission pilots and a pilot in the set of retransmission pilots; and the mapping information includes the mapping between the initial pilot and the retransmission pilot. ### Claim 25 (depends on 24) The user equipment of claim 24, wherein the at least one antenna is configured to receive the mapping information from the base station. ### Claim 26 (depends on 24) The user equipment of claim 24, wherein the number of unique pilots in the set of initial transmission pilots exceeds the number of unique pilots in the set of retransmission pilots. ### Claim 27 (depends on 23) The user equipment of claim 23 wherein the grant-free transmission module is further configured to wait for a duration of a back-off window before transmitting the subsequent grant-free uplink transmission. ### Claim 28 (depends on 23) The user equipment of claim 23, wherein the initial data has a first modulation and coding scheme (MCS) that is associated with the initial pilot, and the retransmission data has a second MCS that is associated with the retransmission pilot.