Uplink HARQ operation for prose-enabled UEs participating in sidelink discovery operation
View Patent ↗The invention relates to an improved transmission protocol for uplink data packet transmission. A transmission counter of the transmission protocol counts the number of transmissions the user terminal has performed for a data packet. The user terminal participates in sidelink discovery operation with other user terminals based on sidelink discovery gaps. The user terminal cannot transmit and/or receive signals under control of the transmission protocol when participating in sidelink discovery operation during the sidelink discovery gaps. A processor of the user terminal determines whether a retransmission of a data packet, which is triggered by the transmission protocol, was not performed because the transmission protocol operation collided with one of the sidelink discovery gaps. In case of collision, the processor operates the transmission counter such that the colliding retransmission of the data packet does not result in an increment of the transmission counter of the transmission protocol for the data packet.
1. A user terminal operating a transmission protocol for:
uplink data packet transmission in a communication system, wherein a transmission counter is configured for the transmission protocol of the user terminal for counting a number of transmissions the user terminal has performed for a data packet,
wherein the user terminal is configured to participate in sidelink discovery operation with other user terminals based on sidelink discovery gaps configured for the user terminal, wherein the user terminal does not transmit and/or receive signals under control of the transmission protocol when participating in sidelink discovery operation during the sidelink discovery gaps,
wherein the user terminal comprises:
a processor configured to determine whether a retransmission of a data packet, which is triggered by the transmission protocol, was not performed because the transmission protocol operation collided with one of the sidelink discovery gaps, and wherein:
in case of collision, the processor being configured to operate the transmission counter such that the colliding retransmission of the data packet does not result in an increment of the transmission counter of the transmission protocol for the data packet, and
the processor being configured to increment the transmission counter of the transmission protocol in response to the retransmission of the data packet being triggered by the transmission protocol, and subsequently decrement the transmission counter of the transmission protocol in response to the retransmission of the data packet not being performed.
2. The user terminal according to claim 1 ,
wherein the user terminal is configured with a sidelink discovery gap for transmission, during which the user terminal can transmit sidelink discovery messages to other user terminals via a sidelink connection, wherein the processor determines that the retransmission of the data packet was not performed because the transmission protocol operation collided with one of the sidelink discovery gaps, when:
a retransmission of the data packet cannot be transmitted because of colliding with the sidelink discovery gap for transmission, when the user terminal transmits a sidelink discovery message during the sidelink discovery gap for transmission,
and/or
the user terminal is configured with a sidelink discovery gap for reception, during which the user terminal monitors for sidelink discovery messages transmitted from other user terminals via a sidelink connection, wherein the processor determines that the retransmission of the data packet was not performed because the transmission protocol operation collided with one of the sidelink discovery gaps, when:
feedback of the transmission protocol relating to a previous transmission of the data packet is not received, because of colliding with the sidelink discovery gap for reception.
3. The user terminal according to claim 1 ,
wherein the transmission protocol provides for the step of incrementing the transmission counter of the transmission protocol by 1 when the retransmission is triggered by the transmission protocol, and wherein the processor is configured to operate the transmission protocol such that the colliding retransmission of the data packet does not result in an increment of the transmission counter for the data packet.
4. The user terminal according to claim 1 ,
wherein a retransmission of a data packet is triggered according to the transmission protocol, when:
a buffer associated with the transmission protocol is not empty and a negative retransmission feedback is pending for the data packet, or
the user terminal receives an uplink grant from a base station to retransmit a previously transmitted data packet.
5. The user terminal according to claim 1 ,
wherein the user terminal is participating in the sidelink discovery on different frequency carriers than the transmission and retransmission of data packets according to the transmission protocol.
6. The user terminal according to claim 1 ,
wherein the user terminal is configured with a maximum number of allowable transmissions of a data packet, and the transmission protocol provides for a step of flushing a buffer of the transmission protocol storing the data packet when the transmission counter reaches the limit of maximum number of allowable transmissions of the data packet.
7. The user terminal according to claim 1 ,
wherein the user terminal is configured with at least one measurement gap during which the user terminal can perform channel measurements, wherein the user terminal does not transmit and/or receive signals under control of the transmission protocol during the measurement gap.
8. A method for operating a transmission protocol in a user terminal for uplink data packet transmission in a communication system, wherein a transmission counter is configured for the transmission protocol of the user terminal for counting a number of transmissions the user terminal has performed for a data packet,
wherein the user terminal is configured to participate in sidelink discovery operation with other user terminals based on sidelink discovery gaps configured for the user terminal, wherein the user terminal does not transmit and/or receive signals under control of the transmission protocol when participating in sidelink discovery operation during the sidelink discovery gaps,
wherein the method comprises the following steps performed by the user terminal:
determining whether a retransmission of a data packet, which is triggered by the transmission protocol, was not performed because the transmission protocol operation collided with one of the sidelink discovery gaps, and
in case of collision, operating the transmission counter such that the colliding retransmission of the data packet does not result in an increment of the transmission counter of the transmission protocol for the data packet by incrementing the transmission counter of the transmission protocol in response to the retransmission of the data packet being triggered by the transmission protocol, and subsequently decrementing the transmission counter of the transmission protocol in response to the retransmission of the data packet not being performed.
9. The method according to claim 8 , wherein the transmission protocol provides for the step of incrementing the transmission counter of the transmission protocol by 1 when the retransmission is triggered by the transmission protocol, and wherein the step of operating the transmission protocol such that the colliding retransmission of the data packet does not result in an increment of the transmission counter for the data packet.
10. The method according to claim 8 , wherein the user terminal is configured with at least one measurement gap during which the user terminal can perform channel measurements, wherein the user terminal does not transmit and/or receive signals under control of the transmission protocol during the measurement gap.