# US 2021/0176751 A1 · Mac-phy model for sidelink carrier (re)selection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0176751 A1 - Document ID: US20210176751A1 - Status: Published application - Kind: A1 - Application number: 17/044,944 - Filed: 2019-04-04 - Published: 2021-06-10 - Earliest claimed: 2018-04-05 - Assignees: Telefonaktiebolaget LM Ericsson (publ) - Applicants: Telefonaktiebolaget LM Ericsson (publ) - Inventors: Marco BELLESCHI; Shehzad Ali ASHRAF - Web page: https://patentgrep.com/patent/US20210176751A1 ## CPC - H04W 72/0453: Resources in frequency domain, e.g. a carrier in FDMA - H04W 76/14: Direct-mode setup - H04L 1/1812: Hybrid protocols; Hybrid automatic repeat request [HARQ] - H04L 5/001: {the frequencies being arranged in component carriers} - H04L 5/0055: {Physical resource allocation for ACK/NACK (for physical mapping arrangements in ARQ protocols H04L1/1861)} - H04W 72/23: in the downlink direction of a wireless link, i.e. towards a terminal - 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) ## Abstract A method in a communication device having a plurality of protocol layers including a media access control, MAC, layer and a physical, PHY, layer, includes, at the MAC layer, selecting a plurality of carriers for carrier aggregation, each of the carriers being associated to a respective hybrid automatic repeat request, HARQ, entity, and at the MAC layer, initiating a sidelink carrier reselection process by the first communication device in response to a triggering event. Related devices and computer program products are disclosed. ## Claims ### Claim 1 A method in a communication device having a plurality of protocol layers including a media access control, MAC, layer and a physical, PHY, layer, the method comprising: at the MAC layer, selecting a plurality of carriers for carrier aggregation, each of the carriers being associated to a respective hybrid automatic repeat request, HARQ, entity; and at the MAC layer, initiating a sidelink carrier reselection process by the first communication device in response to a triggering event, the triggering event comprising at least one of: there is no configured sidelink grant in any sidelink carrier; a configured sidelink grant cannot accommodate an RLC SDU by using a maximum allowed modulation and coding scheme, MCS, configured by upper layers for any sidelink carrier with configured SL grant and the MAC entity selects not to segment the RLC SDU; transmission(s) with a configured sidelink grant cannot fulfil a latency requirement of data in a sidelink logical channel for any sidelink carrier with a configured sidelink grant, and the MAC selects not to perform transmission(s) corresponding to a single MAC PDU. ### Claim 2 (depends on 1) The method of claim 1, wherein initiating the sidelink carrier reselection process is performed only for the carrier and associated HARQ event associated with the triggering event: wherein the triggering event comprises at least one of: for a specific carrier/HARQ entity, if an SL_RESOURCE_RESELECTION_COUNTER=0 and, when the SL_RESOURCE_RESELECTION_COUNTER was equal to 1, the MAC randomly selected, with equal probability, a value in an interval [0, 1] which is above a probability configured by upper layers; neither transmission nor retransmission has been performed by MAC on any resource indicated in a configured sidelink grant during a previous second for a specific carrier/HARQ entity; sl-ReselectAfter is configured and a number of consecutive unused transmission opportunities on resources indicated in the configured sidelink grant is equal to sl-ReselectAfter, for a specific carrier/HARQ entity; and/or a pool of resources is configured or reconfigured by upper layers for a specific carrier. ### Claim 3 (depends on 1) The method of claim 1, wherein initiating the sidelink carrier reselection process is performed for all sidelink carriers configured for sidelink operations; wherein the triggering event comprises at least one of: UE capability and/or power limitations are experienced by potential simultaneous transmissions in multiple carriers; and/or transmissions with a configured sidelink grant are such that the UE is unable to listen/sense the carriers for a long time due to half duplex limitation. ### Claim 4 (depends on 1) The method of claim 1, further comprising: after initiating the sidelink carrier reselection process, performing at least one of: continuing to use a previous carrier and performing resource reselection on the previous carrier; selecting a second sidelink carrier and configuring a second sidelink grant on the second sidelink carrier; and ceasing to use the sidelink carrier and not selecting any other sidelink carrier. ### Claim at position 5 5-6. (canceled) ### Claim 7 A first wireless device comprising: a transceiver configured to provide wireless network communication with a wireless communication network using a plurality of protocol layers including a media access control, MAC, layer; and a processor coupled with the transceiver, wherein the processor is configured to provide wireless network communication through the transceiver, and wherein the processor is configured to perform operations comprising: at the MAC layer, selecting a plurality of carriers for carrier aggregation, each of the carriers being associated to a respective hybrid automatic repeat request, HARQ, entity; and at the MAC layer, initiating a sidelink carrier reselection process by the first communication device in response to a triggering event, the triggering event comprising at least one of: there is no configured sidelink grant in any sidelink carrier; a configured sidelink grant cannot accommodate an RLC SDU by using a maximum allowed modulation and coding scheme, MCS, configured by upper layers for any sidelink carrier with configured SL grant and the MAC entity selects not to segment the RLC SDU; transmission(s) with a configured sidelink grant cannot fulfil a latency requirement of data in a sidelink logical channel for any sidelink carrier with a configured sidelink grant, and the MAC selects not to perform transmission(s) corresponding to a single MAC PDU. ### Claim at position 7 8-11. (canceled) ### Claim 12 (depends on 1) A computer program product comprising a non-transitory storage medium including program code to be executed by processing circuitry of a communication device configured to operate in a communication network, whereby execution of the program code causes the communication device to perform operations according to claim 1. ### Claim 13 A method in a first communication device having a plurality of protocol layers including a media access control, MAC, layer and a physical, PHY, layer, the method comprising: receiving, at the MAC layer, data for transmission over a sidelink interface to a second communication device; generating, at the MAC layer, first and second MAC protocol data units, PDUs, from the data; providing the first and second MAC PDUs from the MAC layer to the PHY layer for simultaneous transmission in a first transmission time interval, TTI, along with an indication of selected first and second carriers from a set of available carriers that the PHY layer should use for transmission of the first and second MAC PDUs in a sidelink transmission to the second communication device, respectively; and receiving, at the MAC layer, an acknowledgement from the PHY layer, the acknowledgement indicating whether or not the simultaneous transmission of the first and second MAC PDUs on the selected first and second carriers was performed successfully. ### Claim 14 (depends on 13) The method of claim 13, wherein the acknowledgement from the PHY layer comprises a negative acknowledgement, NAK, the NAK indicating that the PHY layer was unable to transmit at least one of the first and second MAC PDUs on the respective selected carrier indicated by the MAC layer. ### Claim at position 11 15-17. (canceled) ### Claim 18 (depends on 13) The method of claim 13, further comprising: for a MAC PDU transmission for which a negative acknowledgement is received at the MAC layer, performing at least one of: excluding the MAC PDU from simultaneous transmission on different carriers in subsequent TTIs; triggering carrier reselection and/or resource reselection for transmission of the MAC PDU in a subsequent TTI excluding time/frequency resources for simultaneous transmissions of MAC PDUs in different carriers as indicated by the PHY layer; returning one or more MAC service data units, SDUs, of the MAC PDU to a radio link control, RLC, buffer; storing information relating to a carrier combination and/or time/frequency resources for which the MAC PDU transmission was unsuccessful; and refraining from advancing a transmission counter relating to the MAC PDU that was not successfully transmitted. ### Claim at position 13 19-22. (canceled) ### Claim 23 (depends on 13) The method of claim 13, wherein the data received at the MAC layer for transmission comprises a radio link control, RLC, layer service data unit, SDU; wherein evaluating whether the first and second MAC PDUs can be transmitted over the first and second carriers, respectively, within the first TTI depends on at least one of: whether the PHY is capable of transmitting on the first and second carriers simultaneously; whether a power budget for transmissions on the first and second carriers is overwhelmed; whether simultaneous transmissions on the first and second carriers may lead to power spectral density, PSD, imbalance; whether a strong interfering node is detected on the first or second carrier; whether the first or second carrier is busy to receiving sidelink data or monitoring Uu transmissions; whether the first or second carrier is busy receiving or transmitting Uu data; and whether the PHY layer is capable of transmitting on the first and second carriers due to a limitation on transmitter switching time. ### Claim 24 (depends on 13) The method of claim 13, further comprising: at the PHY layer, evaluating whether the first and second MAC PDUs can be transmitted over the first and second carriers, respectively, within the first TTI; and generating the acknowledgement indicating whether or not the simultaneous transmission of the first and second MAC PDUs on the selected first and second carriers was performed successfully based at least in part on the evaluation. ### Claim 25 (canceled) ### Claim 26 A first wireless device comprising: a transceiver configured to provide wireless network communication with a wireless communication network using a plurality of protocol layers including a media access control, MAC, layer and a physical, PHY, layer; and a processor coupled with the transceiver, wherein the processor is configured to provide wireless network communication through the transceiver, and wherein the processor is configured to perform operations comprising: receiving, at the MAC layer, data for transmission over a sidelink interface to a second communication device; generating, at the MAC layer, first and second MAC protocol data units, PDUs, from the data; providing the first and second MAC PDUs from the MAC layer to the PHY layer for simultaneous transmission in a first transmission time interval, TTI, along with an indication of selected first and second carriers from a set of available carriers that the PHY layer should use for transmission of the first and second MAC PDUs in a sidelink transmission to the second communication device, respectively; and receiving, at the MAC layer, an acknowledgement from the PHY layer, the acknowledgement indicating whether or not the simultaneous transmission of the first and second MAC PDUs on the selected first and second carriers was performed successfully. ### Claim at position 18 27-30. (canceled) ### Claim 31 (depends on 13) A computer program product comprising a non-transitory storage medium including program code to be executed by processing circuitry of a communication device configured to operate in a communication network, whereby execution of the program code causes the communication device to perform operations according to claim 13. ### Claim at position 20 32-39. (canceled) ### Claim 40 A method in a first communication device having a plurality of protocol layers including a media access control, MAC, layer and a physical, PHY, layer, the method comprising: receiving, at the MAC layer, data for transmission over a sidelink interface to a second communication device; generating, at the MAC layer, first and second MAC protocol data units, PDUs, from the data; receiving information from the PHY layer regarding the availability of one or more carriers for transmitting the first and second MAC PDUs; performing a carrier selection or reselection procedure to select first and second carriers from the one or more carriers for transmission of the first and second MAC PDUs based on the information from the PHY layer; and providing the first and second MAC PDUs from the MAC layer to the PHY layer for simultaneous transmission in a first transmission time interval, TTI, along with an indication of the selected first and second carriers. ### Claim 41 (depends on 40) The method of claim 40, wherein the information from the PHY layer comprises one of: an indication of a carrier or time/frequency resources on the carrier that the MAC layer should not select for simultaneous transmission in future TTIs; an indication of a carrier combination and/or time/frequency resources that the information from the PHY layer indicates is unavailable for transmission; and an indication of a carrier combination and/or time/frequency resources that the information from the PHY layer indicates is available for transmission. ### Claim at position 23 42-43. (canceled) ### Claim 44 (depends on 40) The method of claim 40, further comprising: triggering carrier reselection and/or resource reselection for transmission of at least one of the first and second MAC PDUs excluding time/frequency resources for simultaneous transmissions of MAC PDUs in different carriers as indicated by the PHY layer; and storing information relating to a carrier combination and/or time/frequency resources that the information from the PHY layer indicates is unavailable for transmission. ### Claim at position 25 45-46. (canceled) ### Claim 47 (depends on 40) The method of any claim 40, further comprising: generating, at the PHY layer, an indication of whether or not simultaneous transmission of the first and second MAC PDUs on the selected first and second carriers can be performed successfully; and transmitting the indication to the MAC layer. ### Claim 48 (depends on 47) The method of claim 47, wherein evaluating whether the first and second MAC PDUs can be transmitted over the first and second carriers, respectively, within the first TTI depends on at least one of: whether the PHY is capable of transmitting on the first and second carriers simultaneously; whether a power budget for transmissions on the first and second carriers is overwhelmed; whether simultaneous transmissions on the first and second carriers may lead to power spectral density, PSD, imbalance; whether a strong interfering node is detected on the first or second carrier; whether the first or second carrier is busy to receiving sidelink data or monitoring Uu transmissions; whether the first or second carrier is busy receiving or transmitting Uu data; and whether the PHY layer is capable of transmitting on the first and second carriers due to a limitation on transmitter switching time. ### Claim 49 A first wireless device comprising: a transceiver configured to provide wireless network communication with a wireless communication network using a plurality of protocol layers including a media access control, MAC, layer and a physical, PHY, layer; and a processor coupled with the transceiver, wherein the processor is configured to provide wireless network communication through the transceiver, and wherein the processor is configured to perform operations comprising: receiving, at the MAC layer, data for transmission over a sidelink interface to a second communication device; generating, at the MAC layer, first and second MAC protocol data units, PDUs, from the data; receiving information from the PHY layer regarding the availability of one or more carriers for transmitting the first and second MAC PDUs; performing a carrier selection or reselection procedure to select first and second carriers from the one or more carriers for transmission of the first and second MAC PDUs based on the information from the PHY layer; and providing the first and second MAC PDUs from the MAC layer to the PHY layer for simultaneous transmission in a first transmission time interval, TTI, along with an indication of the selected first and second carriers. ### Claim at position 29 50-53. (canceled) ### Claim 54 (depends on 40) A computer program product comprising a non-transitory storage medium including program code to be executed by processing circuitry of a communication device configured to operate in a communication network, whereby execution of the program code causes the communication device to perform operations according to claim 40. ### Claim 55 (depends on 7) The first wireless device of claim 7, wherein initiating the sidelink carrier reselection process is performed only for the carrier and associated HARQ event associated with the triggering event; wherein the triggering event comprises at least one of: for a specific carrier/HARQ entity, if an SL_RESOURCE_RESELECTION_COUNTER=0 and, when the SL_RESOURCE_RESELECTION_COUNTER was equal to 1, the MAC randomly selected, with equal probability, a value in an interval [0, 1] which is above a probability configured by upper layers; neither transmission nor retransmission has been performed by MAC on any resource indicated in a configured sidelink grant during a previous second for a specific carrier/HARQ entity; sl-ReselectAfter is configured and a number of consecutive unused transmission opportunities on resources indicated in the configured sidelink grant is equal to sl-ReselectAfter, for a specific carrier/HARQ entity; and/or a pool of resources is configured or reconfigured by upper layers for a specific carrier. ### Claim 56 (depends on 7) The first wireless device of claim 7, wherein initiating the sidelink carrier reselection process is performed for all sidelink carriers configured for sidelink operations; wherein the triggering event comprises at least one of: UE capability and/or power limitations are experienced by potential simultaneous transmissions in multiple carriers; and/or transmissions with a configured sidelink grant are such that the UE is unable to listen/sense the carriers for a long time due to half duplex limitation. ### Claim 57 (depends on 7) The first wireless device of claim 7, further comprising: after initiating the sidelink carrier reselection process, performing at least one of: continuing to use a previous carrier and performing resource reselection on the previous carrier; selecting a second sidelink carrier and configuring a second sidelink grant on the second sidelink carrier; and ceasing to use the sidelink carrier and not selecting any other sidelink carrier. ### Claim 58 (depends on 26) The first wireless device of claim 26, wherein the operations further comprise: for a MAC PDU transmission for which a negative acknowledgement is received at the MAC layer, performing at least one of: excluding the MAC PDU from simultaneous transmission on different carriers in subsequent TTIs; triggering carrier reselection and/or resource reselection for transmission of the MAC PDU in a subsequent TTI excluding time/frequency resources for simultaneous transmissions of MAC PDUs in different carriers as indicated by the PHY layer; returning one or more MAC service data units, SDUs, of the MAC PDU to a radio link control, RLC, buffer; storing information relating to a carrier combination and/or time/frequency resources for which the MAC PDU transmission was unsuccessful; and refraining from advancing a transmission counter relating to the MAC PDU that was not successfully transmitted. ### Claim 59 (depends on 26) The first wireless device of claim 26, wherein the operations further comprise: at the PHY layer, evaluating whether the first and second MAC PDUs can be transmitted over the first and second carriers, respectively, within the first TTI; and generating the acknowledgement indicating whether or not the simultaneous transmission of the first and second MAC PDUs on the selected first and second carriers was performed successfully based at least in part on the evaluation. ### Claim 60 (depends on 49) The first wireless device of claim 49, wherein the information from the PHY layer comprises one of: an indication of a carrier or time/frequency resources on the carrier that the MAC layer should not select for simultaneous transmission in future TTIs; an indication of a carrier combination and/or time/frequency resources that the information from the PHY layer indicates is unavailable for transmission; and an indication of a carrier combination and/or time/frequency resources that the information from the PHY layer indicates is available for transmission.