Handling unexpected configuration cases in a sidelink relay network

Abstract

Handling communication in a Sidelink Relay network, including a Remote UE and a Relay UE, comprises handling, by the Remote UE and / or the Relay UE, of an error and / or a misconfiguration. The Remote UE may discard a packet received thereby if a UE ID of the packet does not match the ID of the Remote UE. The Remote UE may discard a packet received thereby if a bearer ID of the packet does not match a bearer for the Remote UE. The Relay UE may discard a packet received thereby if a UE ID of the packet is not included in a configuration table. The Relay UE may discard a packet received thereby if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet does not match a bearer included in the configuration table for the UE ID. The Relay UE may remove a configuration table upon Uu RLF detection / notification or upon reception of an RRCReconfiguration including the reconfigurationWithSync. The Relay UE may release a SRAP (Sidelink Relay Adaption Protocol) entity.

Description

Field The present invention relates to sidelink relay networks, for example to handling configuration cases in sidelink relay networks. Background to the invention Figures 1 and 2 respectively show User and Control plane protocol stacks 1,2 for L2 UE-to-NW Relay, as captured in the 3GPP TR 38.836v17.0.0. 3GPP agreed to introduce the Adapt layer on the Uu link (link between Relay UE 12, 22 and the gNB 13, 23), as shown in the above figures in shaded boxes. Presence of a separate Adapt layer on the Sidelink (SL) i.e. PC5 link (between Remote UE and Relay UE) has also been confirmed by 3GPP RAN2 (but is not shown in the above diagrams). The main agreed functionality of Adapt is mapping of UL PC5 bearers onto Uu bearers, and performing the inverse process on the DL. This Adapt layer was recently (re)named Sidelink Relay Adaptation Protocol, or SRAP for short. As captured in R2-2201996 (the most recent version of TS 38.351 specification draft, capturing SRAP), the following is the basic model and operation of SRAP as agreed by 3GPP: On the U2N Relay UE 12, 22, the SRAP sublayer contains one SRAP entity at Uu interface and a separate collocated SRAP entity at the PC5 interface. On the U2N Remote UE 11, 21, the SRAP sublayer contains only one SRAP entity at the PC5 interface. Each SRAP entity has a transmitting part and a receiving part. Across the PC5 interface, the transmitting part of the SRAP entity at the U2N Remote UE 11, 21 has a corresponding receiving part of an SRAP entity at the U2N Relay UE 12, 22, and vice-versa. Across the Uu interface, the transmitting part of the SRAP entity 126, 226 at the U2N Relay UE 12, 22 has a corresponding receiving part of an SRAP entity 136, 236 at the gNB, and vice-versa. At the Remote UE 11, 21, in the uplink (UL) direction the SRAP will determine SRAP UE ID and BEARER ID and add the SRAP header. At the Remote UE 11, 21, on the downlink (DL), the SRAP will remove the SRAP header and deliver the packet to higher layers. At the Relay UE 12, 22, on the UL the SRAP will map the packet from a PC5 channel to a Uu channel using the SRAP UE ID and BEARER ID contained in the packet itself, and the mapping configuration provided by the network. At the Relay UE 12, 22, on the DL the SRAP will map the packet from a Uu channel to a PC5 channel using SRAP UE ID and BEARER ID contained in the packet itself, and the mapping configuration provided by the network. However, there remains a need to improve handling of configuration cases in sidelink relay networks. Summary of the Invention A first aspect provides a method of handling communication in a Sidelink Relay network, including a Remote UE and a Relay UE, the method comprising: handling, by the Remote UE and / or the Relay UE, an error and / or a misconfiguration. A second aspect provides a Sidelink Relay network, including a Remote UE and a Relay UE, configured to implement a method according to the first aspect. Detailed Description of the Invention According to the present invention there is provided a method, as set forth in the appended claims. Also provided is a network. Other features of the invention will be apparent from the dependent claims, and the description that follows. Method The first aspect provides a method of handling communication in a Sidelink Relay network, including a Remote UE and a Relay UE, the method comprising: handling, by the Remote UE and / or the Relay UE, an error and / or a misconfiguration. In one example, handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises discarding, by the Remote UE, a packet received thereby if a UE ID of the packet does not match the ID of the Remote UE. In one example, handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises discarding, by the Remote UE, a packet received thereby if a bearer ID of the packet does not match a bearer for the Remote UE. In one example, handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises discarding, by the Relay UE, a packet received thereby if a UE ID of the packet is not included in a configuration table. In one example, handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises discarding, by the Relay UE, a packet received thereby if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet does not match a bearer included in the configuration table for the UE ID. In one example, handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises sending, by the Relay UE, a packet received thereby on a default channel if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet does not match a bearer included in the configuration table for the UE ID. In one example, the default channel is a dedicated, pre-configured and / or configurable mapping between an RLC channel ID (i.e. the default channel) and one or more E2E bearer IDs. In one example, handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises sending, by the Relay UE, a packet received thereby on a channel selected based on prioritization if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a plurality of bearers included in the configuration table for the UE ID. In one example, handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises sending, by the Relay UE, a packet received thereby on a channel selected randomly if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a plurality of bearers included in the configuration table for the UE ID. In one example, handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises sending, by the Relay UE, a packet received thereby on a channel selected based on QoS requirements if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a plurality of bearers included in the configuration table for the UE ID. In one example, handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises selectively discarding, by the Relay UE, a packet received thereby if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a bearer included in the configuration table for the UE ID and if a determined egress link is in RLF or congested. In one example, handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises discarding, by the Relay UE, a packet received thereby if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a bearer included in the configuration table for the UE ID and if the Relay UE is to change its serving cell, for example due to RRCReconfiguration. In one example, handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises removing, by the Relay UE, a configuration table upon Uu RLF detection / notification or upon reception of an RRCReconfiguration including the reconfigurationWithSync. In one example, handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises forwarding, by the Relay UE, a buffered packet before removing, by the Relay UE, a configuration table. In one example, handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises re-routing via a different Remote UE, by the Relay UE, a packet received thereby if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a bearer included in the configuration table for the UE ID and if a determined egress link is in RLF or if the Relay UE is to change its serving cell, for example due to RRCReconfiguration. In one example, handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises releasing, at the Relay UE, a SRAP entity. Network The second aspect provides a Sidelink Relay network, including a Remote UE and a Relay UE, configured to implement a method according to the first aspect. Definitions Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of other components. The term “consisting essentially of’ or “consists essentially of’ means including the components specified but excluding other components except for materials present as impurities, unavoidable materials present as a result of processes used to provide the components, and components added for a purpose other than achieving the technical effect of the invention, such as colourants, and the like. The term “consisting of’ or “consists of means including the components specified but excluding other components. Whenever appropriate, depending upon the context, the use of the term “comprises” or “comprising” may also be taken to include the meaning “consists essentially of or “consisting essentially of, and also may also be taken to include the meaning “consists of or “consisting of. The optional features set out herein may be used either individually or in combination with each other where appropriate and particularly in the combinations as set out in the accompanying claims. The optional features for each aspect or exemplary embodiment of the invention, as set out herein are also applicable to all other aspects or exemplary embodiments of the invention, where appropriate. In other words, the skilled person reading this specification should consider the optional features for each aspect or exemplary embodiment of the invention as interchangeable and combinable between different aspects and exemplary embodiments. Brief description of the drawings For a better understanding of the invention, and to show how exemplary embodiments of the same may be brought into effect, reference will be made, by way of example only, to the accompanying diagrammatic Figures, in which: Figure 1 schematically depicts a User plane protocol stack for L2 UE-to-NW Relay, as captured in the 3GPP TR 38.836v17.0.0; Figure 2 schematically depicts a Control plane protocol stack for L2 UE-to-NW Relay, as captured in the 3GPP TR 38.836v17.0.0; Figure 3 schematically depicts a User plane protocol stack for L2 UE-to-NW Relay, according to an exemplary embodiment; Figure 4 schematically depicts a Control plane protocol stack for L2 UE-to-NW Relay, according to an exemplary embodiment; and Figure 5 schematically depicts a method according to an exemplary embodiment. Detailed Description of the Drawings Figure 1 schematically depicts a User plane protocol stack 1 forL2 UE-to-NW Relay, as captured in the 3GPP TR 38.836v17.0.0. In more detail, the User plane protocol stack 1 comprises a Remote UE 11, a UE-to-Network Relay UE 12, a gNB 13 and a 5GC 14. The Remote UE 11 comprises an IP entity 110, a Uu-SDAP entity 111 on a SDAP sublayer and a Uu-PDCP entity 112 on a PDCP sublayer. The Remote UE 21 comprises a PC5-RLC entity 113 on a RLC sublayer, a PC5-MAC entity 114 on a MAC sublayer and a PC5-PHY entity 115 on a PHY sublayer. It should be understood that the sublayers (also known as layers) are of the network. The UE-to-Network Relay UE 12 comprises a PC5-RLC entity 123 on the RLC sublayer, a PC5-MAC entity 124 on the MAC sublayer and a PC5-PHY entity 125 on the PHY sublayer, respectively communicatively interfaced with the corresponding PC5-RLC entity 113, PC5-MAC entity 114 and PC5-PHY entity 115 of the Remote UE 11 via a RLC Channel 1112. The UE-to-Network Relay UE 12 comprises an ADAPT entity 126 on an ADAPT layer, a Uu-RLC entity 127 on the RLC sublayer, a Uu-MAC entity 128 on the MAC sublayer and a Uu-PHY entity 129 on the PHY sublayer. The gNB 13 comprises a Uu-SDAP entity 131 on the SDAP sublayer and a Uu-PDCP entity 132 on the PDCP sublayer, respectively communicatively interfaced with the corresponding Uu-SDAP entity 111 and Uu-PDCP entity 112 of the Remote UE 11. The gNB 13 comprises an ADAPT entity 136 on the ADAPT layer, a Uu-RLC entity 137 on the RLC sublayer, a Uu-MAC entity 138 on the MAC sublayer and a Uu-PHY entity 139 on the PHY sublayer, respectively communicatively interfaced with the corresponding ADAPT entity 126, Uu-RLC entity 127, Uu-MAC entity 128 and Uu-PHY entity 129 of the UE-to-Network Relay UE 12 via a Uu DRB 1213. The gNB 13 comprises a N3 Stack 13N3. The 5GC 14 comprises an IP entity 140, communicatively interfaced with the corresponding IP entity 110 of the Remote UE 11. The 5GC 14 comprises a N3 Stack 14N3, communicatively interfaced with the corresponding N3 Stack 13N3 of the gNB 13 via a GTP-U Tunnel 1314. Figure 2 schematically depicts a Control plane protocol stack 2 for L2 UE-to-NW Relay, as captured in the 3GPP TR 38.836v17.0.0. In more detail, the Control plane protocol stack 2 comprises a Remote UE 21, a UE-to-Network Relay UE 22, a gNB 23 and a 5GC 24. The Remote UE 21 comprises a NAS entity 210, a Uu-RRC entity 211 on a RRC sublayer and a Uu-PDCP entity 212 on a PDCP sublayer. The Remote UE 21 comprises a PC5-RLC entity 213 on a RLC sublayer, a PC5-MAC entity 214 on a MAC sublayer and a PC5-PHY entity 215 on a PHY sublayer. It should be understood that the sublayers (also known as layers) are of the network. The UE-to-Network Relay UE 22 comprises a PC5-RLC entity 223 on the RLC sublayer, a PC5-MAC entity 224 on the MAC sublayer and a PC5-PHY entity 225 on the PHY sublayer, respectively communicatively interfaced with the corresponding PC5-RLC entity 213, PC5-MAC entity 214 and PC5-PHY entity 215 of the Remote UE 21 via a RLC Channel 2112. The UE-to-Network Relay UE 22 comprises an ADAPT entity 226 on an ADAPT layer, a Uu-RLC entity 227 on the RLC sublayer, a Uu-MAC entity 228 on the MAC sublayer and a Uu-PHY entity 229 on the PHY sublayer. The gNB 23 comprises a Uu-RRC entity 231 on the RRC sublayer and a Uu-PDCP entity 232 on the PDCP sublayer, respectively communicatively interfaced with the corresponding Uu-RRC entity 211 and Uu-PDCP entity 212 of the Remote UE 21. The gNB 23 comprises an ADAPT entity 236 on the ADAPT layer, a Uu-RLC entity 237 on the RLC sublayer, a Uu-MAC entity 238 on the MAC sublayer and a Uu-PHY entity 239 on the PHY sublayer, respectively communicatively interfaced with the corresponding ADAPT entity 226, Uu-RLC entity 227, Uu-MAC entity 228 and Uu-PHY entity 229 of the UE-to-Network Relay UE 22 via a Uu DRB 2223. The gNB 23 comprises a N2 Stack 23N2. The 5GC 24 comprises an NAS entity 240, communicatively interfaced with the corresponding NAS entity 210 of the Remote UE 21. The 5GC comprises a N2 Stack 24N2, communicatively interfaced with the corresponding N2 Stack 23N2 of the gNB 23 via a N2 2324. Figures 1 and 2 respectively show User and Control plane protocol stacks 1,2 for L2 UE-to-NW Relay, as captured in the 3GPP TR 38.836v17.0.0. 3GPP agreed to introduce the Adapt layer on the Uu link (link between Relay UE 12, 22 and the gNB 13, 23), as shown in the above figures in shaded boxes. Presence of a separate Adapt layer on the Sidelink (SL) i.e. PC5 link (between Remote UE and Relay UE) has also been confirmed by 3GPP RAN2 (but is not shown in the above diagrams). The main agreed functionality of Adapt is mapping of UL PC5 bearers onto Uu bearers, and performing the inverse process on the DL. This Adapt layer was recently (re)named Sidelink Relay Adaptation Protocol, or SRAP for short. As captured in R2-2201996 (the most recent version of TS 38.351 specification draft, capturing SRAP), the following is the basic model and operation of SRAP as agreed by 3GPP: - On the U2N Relay UE 12, 22, the SRAP sublayer contains one SRAP entity at Uu interface and a separate collocated SRAP entity at the PC5 interface. On the U2N Remote UE 11, 21, the SRAP sublayer contains only one SRAP entity at the PC5 interface. Each SRAP entity has a transmitting part and a receiving part. Across the PC5 interface, the transmitting part of the SRAP entity at the U2N Remote UE 11, 21 has a corresponding receiving part of an SRAP entity at the U2N Relay UE 12, 22, and vice-versa. Across the Uu interface, the transmitting part of the SRAP entity 126, 226 at the U2N Relay UE 12, 22 has a corresponding receiving part of an SRAP entity 136, 236 at the gNB, and vice-versa. - At the Remote UE 11, 21, in the uplink (UL) direction the SRAP will determine SRAP UE ID and BEARER ID and add the SRAP header. At the Remote UE 11, 21, on the downlink (DL), the SRAP will remove the SRAP header and deliver the packet to higher layers. At the Relay UE 12, 22, on the UL the SRAP will map the packet from a PC5 channel to a Uu channel using the SRAP UE ID and BEARER ID contained in the packet itself, and the mapping configuration provided by the network. At the Relay UE 12, 22, on the DL the SRAP will map the packet from a Uu channel to a PC5 channel using SRAP UE ID and BEARER ID contained in the packet itself, and the mapping configuration provided by the network. Figure 3 schematically depicts a User plane protocol stack 3 for L2 UE-to-NW Relay, according to an exemplary embodiment. In more detail, the User plane protocol stack 3 comprises a Remote UE 31, a UE-to-Network Relay UE 32, a gNB 33 and a 5GC 34. The Remote UE 31 comprises an IP entity 310, a Uu-SDAP entity 311 on a SDAP sublayer and a Uu-PDCP entity 312 on a PDCP sublayer. The Remote UE 21 comprises a PC5-RLC entity 313 on a RLC sublayer, a PC5-MAC entity 314 on a MAC sublayer and a PC5-PHY entity 315 on a PHY sublayer. It should be understood that the sublayers (also known as layers) are of the network. The UE-to-Network Relay UE 32 comprises a PC5-RLC entity 323 on the RLC sublayer, a PC5-MAC entity 324 on the MAC sublayer and a PC5-PHY entity 325 on the PHY sublayer, respectively communicatively interfaced with the corresponding PC5-RLC entity 313, PC5-MAC entity 314 and PC5-PHY entity 315 of the Remote UE 31 via a RLC Channel 3132. The UE-to-Network Relay UE 32 comprises an ADAPT entity 326 on an ADAPT layer, a Uu-RLC entity 327 on the RLC sublayer, a Uu-MAC entity 328 on the MAC sublayer and a Uu-PHY entity 329 on the PHY sublayer. The gNB 33 comprises a Uu-SDAP entity 331 on the SDAP sublayer and a Uu-PDCP entity 332 on the PDCP sublayer, respectively communicatively interfaced with the corresponding Uu-SDAP entity 311 and Uu-PDCP entity 312 of the Remote UE 31. The gNB 33 comprises an ADAPT entity 336 on the ADAPT layer, a Uu-RLC entity 337 on the RLC sublayer, a Uu-MAC entity 338 on the MAC sublayer and a Uu-PHY entity 339 on the PHY sublayer, respectively communicatively interfaced with the corresponding ADAPT entity 326, Uu-RLC entity 327, Uu-MAC entity 328 and Uu-PHY entity 329 of the UE-to-Network Relay UE 32 via a Uu DRB 3233. The gNB 33 comprises a N3 Stack 33N3. The 5GC 34 comprises an IP entity 340, communicatively interfaced with the corresponding IP entity 310 of the Remote UE 31. The 5GC 34 comprises a N3 Stack 34N3, communicatively interfaced with the corresponding N3 Stack 33N3 of the gNB 33 via a GTP-U Tunnel 3334. Figure 4 schematically depicts a Control plane protocol stack 4 for L2 UE-to-NW Relay, according to an exemplary embodiment. In more detail, the Control plane protocol stack 4 comprises a Remote UE 41, a UE-to-Network Relay UE 42, a gNB 43 and a 5GC 44. The Remote UE 41 comprises a NAS entity 410, a Uu-RRC entity 411 on a RRC sublayer and a Uu-PDCP entity 412 on a PDCP sublayer. The Remote UE 41 comprises a PC5-RLC entity 413 on a RLC sublayer, a PC5-MAC entity 414 on a MAC sublayer and a PC5-PHY entity 415 on a PHY sublayer. It should be understood that the sublayers (also known as layers) are of the network. The UE-to-Network Relay UE 42 comprises a PC5-RLC entity 423 on the RLC sublayer, a PC5-MAC entity 424 on the MAC sublayer and a PC5-PHY entity 425 on the PHY sublayer, respectively communicatively interfaced with the corresponding PC5-RLC entity 413, PC5-MAC entity 414 and PC5-PHY entity 415 of the Remote UE 41 via a RLC Channel 4142. The UE-to-Network Relay UE 42 comprises an ADAPT entity 426 on an ADAPT layer, a Uu-RLC entity 427 on the RLC sublayer, a Uu-MAC entity 428 on the MAC sublayer and a Uu-PHY entity 429 on the PHY sublayer. The gNB 43 comprises a Uu-RRC entity 431 on the RRC sublayer and a Uu-PDCP entity 432 on the PDCP sublayer, respectively communicatively interfaced with the corresponding Uu-RRC entity 411 and Uu-PDCP entity 412 of the Remote UE 41. The gNB 43 comprises an ADAPT entity 436 on the ADAPT layer, a Uu-RLC entity 437 on the RLC sublayer, a Uu-MAC entity 438 on the MAC sublayer and a Uu-PHY entity 439 on the PHY sublayer, respectively communicatively interfaced with the corresponding ADAPT entity 426, Uu-RLC entity 427, Uu-MAC entity 428 and Uu-PHY entity 429 of the UE-to-Network Relay UE 42 via a Uu DRB 4243. The gNB 43 comprises a N2 Stack 43N2. The 5GC 44 comprises an NAS entity 440, communicatively interfaced with the corresponding NAS entity 410 of the Remote UE 41. The 5GC comprises a N2 Stack 44N2, communicatively interfaced with the corresponding N2 Stack 43N2 of the gNB 43 via a N2 4344. In more detail, this invention deals with handling of unknown, unforeseen, and erroneous protocol data. Handling of error cases and misconfiguration at Remote UE 31, 41: At Remote UE 31,41, if a packet is received with UE ID not matching that UE, the packet is discarded. At Remote UE 31, 41, if a packet is received with UE ID matching that UE but whose bearer ID does not matching any bearer for that UE, the packet is discarded. Handling of error cases and misconfiguration at Relay UE 32, 42: At Relay UE 32, 42, if a packet is received whose UE ID does not appear in the configuration table, the packet is discarded. At Relay UE 32, 42, if a packet is received whose UE ID appears in the configuration table but the relevant entries do not match the BEARER ID, the packet is discarded. At Relay UE 32, 42, if a packet is received whose UE ID appears in the configuration table but the relevant entries do not match the BEARER ID, the packet is sent on a default channel. This default channel can be part of the initial Relay UE 32, 42 configuration by the network, and can also be re-configurable. In an embodiment of this invention, the default channel is a dedicated, preconfigured and / or configurable mapping between an RLC channel ID (= the default channel) and one or more E2E bearer IDs (identified by the BEARER ID in the SRAP packet). In a refinement of this embodiment, there is an explicit indication about default channel for this erroneous case to distinguish it from normal use case contained in the E2E bearer<->RLC channel configuration (i.e. Relay UE 32, 42 SRAP configuration). At Relay UE 32, 42, if a packet is received whose UE ID appears in the configuration table and multiple entries match the BEARER ID, and a prioritization is configured among these multiple entries (e.g. by the network), the packet is sent on a channel chosen in descending order of priority of the matched entries. At Relay UE 32, 42, if a packet is received whose UE ID appears in the configuration table and multiple entries match the BEARER ID, the packet is sent on a channel randomly chosen by the Relay UE 32, 42. At Relay UE 32, 42, if a packet is received whose UE ID appears in the configuration table and multiple entries match the BEARER ID, the packet is sent on a channel with conditions which match the QoS requirements e.g. priority, BER, PER, delay requirements / packet delay budget. At Relay UE 32, 42, if a packet is received whose UE ID appears in the configuration table and a single entry matches the BEARER ID but the determined egress link is in RLF (Radio Link Failure, i.e. unavailable), the packet is discarded. At Relay UE 32, 42, if a packet is received whose UE ID appears in the configuration table and a single entry matches the BEARER ID but the determined egress link is congested (i.e. technically available but overloaded), the packet is discarded. At Relay UE 32, 42, if a packet is received whose UE ID appears in the configuration table and a single entry matches the BEARER ID but the determined egress link is congested (i.e. technically available but overloaded), the packet is discarded (or not) depending on its related QoS requirements (e.g. if the packet will soon expire, or if the packet delay budget is unlikely to be met). At Relay UE 32, 42, if a packet is received whose UE ID appears in the configuration table and a single entry matches the BEARER ID but Relay UE 32, 42 is to change its serving cell due to RRCReconfiguration (including the reconfigurationWithSync), the packet is discarded. In a refinement, upon Uu RLE detection / notification or upon reception of an RRCReconfiguration including the reconfigurationWithSync, Relay UE 32, 42 removes the configuration table. Alternatives / enhancements for above Uu RLF and handover case, to cover any possibility that Relay UE 32, 42 has packets buffered for transmission immediately before removing the configuration table due to Uu RLF / handover: At Relay UE 32, 42, if a packet is received whose UE ID appears in the configuration table and a single entry matches the BEARER ID but the determined egress link is in RLF (i.e. unavailable), the packet is forwarded to Remote UE 31,41 or gNB 33, 43 before removing the configuration table. At Relay UE 32, 42, if a packet is received whose UE ID appears in the configuration table and a single entry matches the BEARER ID but Relay UE 32, 42 is to change its serving cell due to RRCReconfiguration including the reconfigurationWithSync, the packet is forwarded to Remote UE 31,41 or gNB 33, 43 before removing the configuration table. At Relay UE 32, 42 (applies to DL only), if a packet is received whose UE ID appears in the configuration table and a single entry matches the BEARER ID but the determined egress link is in RLF (i.e. unavailable), the packet is re-routed via a different Remote UE 31,41. At Relay UE 32, 42 (applies to DL only), if a packet is received whose UE ID appears in the configuration table and a single entry matches the BEARER ID but Relay UE 32, 42 is to change its serving cell due to RRCReconfiguration including the reconfigurationWithSync, the packet is re-routed via a different Remote UE 31,41. In case of PC5 RLF or Uu RLF notification from Relay UE 32, 42, or Relay UE 32, 42’s serving cell change (RRCReconfiguration including the reconfigurationWithSync) notification from Relay UE 32, 42 or PC5 RRC release by upper layer request, SRAP entity at Remote UE 31,41 is released. In case of PC5 RLF or Uu RLF or Relay UE’s 32, 42 serving cell change (RRCReconfiguration including the reconfigurationWithSync) or PC5 RRC release by upper layer request, SRAP entity at Relay UE 32, 42 is released. The first aspect provides a method of handling communication in a Sidelink Relay network, including the Remote UE 31,41 and the Relay UE 32, 42, the method comprising: handling, by the Remote UE 31, 41 and / or the Relay UE 32, 42, an error and / or a misconfiguration. Optionally, in this example, handling, by the Remote UE 31,41 and / or the Relay UE 32, 42, the error and / or the misconfiguration comprises discarding, by the Remote UE 31, 41, a packet received thereby if a UE ID of the packet does not match the ID of the Remote UE 31,41. Optionally, in this example, handling, by the Remote UE 31,41 and / or the Relay UE 32, 42, the error and / or the misconfiguration comprises discarding, by the Remote UE 31, 41, a packet received thereby if a bearer ID of the packet does not match a bearer for the Remote UE 31,41. Optionally, in this example, handling, by the Remote UE 31,41 and / or the Relay UE 32, 42, the error and / or the misconfiguration comprises discarding, by the Relay UE 32, 42, a packet received thereby if a UE ID of the packet is not included in a configuration table. Optionally, in this example, handling, by the Remote UE 31,41 and / or the Relay UE 32, 42, the error and / or the misconfiguration comprises discarding, by the Relay UE 32, 42, a packet received thereby if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet does not match a bearer included in the configuration table for the UE ID. Optionally, in this example, handling, by the Remote UE 31,41 and / or the Relay UE 32, 42, the error and / or the misconfiguration comprises sending, by the Relay UE 32, 42, a packet received thereby on a default channel if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet does not match a bearer included in the configuration table for the UE ID. Optionally, in this example, the default channel is a dedicated, pre-configured and / or configurable mapping between an RLC channel ID (i.e. the default channel) and one or more E2E bearer IDs. Optionally, in this example, handling, by the Remote UE 31,41 and / or the Relay UE 32, 42, the error and / or the misconfiguration comprises sending, by the Relay UE 32, 42, a packet received thereby on a channel selected based on prioritization if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a plurality of bearers included in the configuration table for the UE ID. Optionally, in this example, handling, by the Remote UE 31,41 and / or the Relay UE 32, 42, the error and / or the misconfiguration comprises sending, by the Relay UE 32, 42, a packet received thereby on a channel selected randomly if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a plurality of bearers included in the configuration table for the UE ID. Optionally, in this example, handling, by the Remote UE 31,41 and / or the Relay UE 32, 42, the error and / or the misconfiguration comprises sending, by the Relay UE 32, 42, a packet received thereby on a channel selected based on QoS requirements if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a plurality of bearers included in the configuration table for the UE ID. Optionally, in this example, handling, by the Remote UE 31,41 and / or the Relay UE 32, 42, the error and / or the misconfiguration comprises selectively discarding, by the Relay UE 32, 42, a packet received thereby if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a bearer included in the configuration table for the UE ID and if a determined egress link is in RLF or congested. Optionally, in this example, handling, by the Remote UE 31,41 and / or the Relay UE 32, 42, the error and / or the misconfiguration comprises discarding, by the Relay UE 32, 42, a packet received thereby if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a bearer included in the configuration table for the UE ID and if the Relay UE 32, 42 is to change its serving cell, for example due to RRCReconfiguration. Optionally, in this example, handling, by the Remote UE 31,41 and / or the Relay UE 32, 42, the error and / or the misconfiguration comprises removing, by the Relay UE 32, 42, a configuration table upon Uu RLF detection / notification or upon reception of an RRCReconfiguration including the reconfigurationWithSync. Optionally, in this example, handling, by the Remote UE 31,41 and / or the Relay UE 32, 42, the error and / or the misconfiguration comprises forwarding, by the Relay UE 32, 42, a buffered packet before removing, by the Relay UE 32, 42, a configuration table. Optionally, in this example, handling, by the Remote UE 31,41 and / or the Relay UE 32, 42, the error and / or the misconfiguration comprises re-routing via a different Remote UE 31,41, by the Relay UE 32, 42, a packet received thereby if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a bearer included in the configuration table for the UE ID and if a determined egress link is in RLF or if the Relay UE 32, 42 is to change its serving cell, for example due to RRCReconfiguration. Optionally, in this example, handling, by the Remote UE 31,41 and / or the Relay UE 32, 42, the error and / or the misconfiguration comprises releasing, at the Relay UE 32, 42, a SRAP entity. The second aspect provides a Sidelink Relay network, including a Remote UE 31,41 and a Relay UE 32, 42, configured to implement a method according to the first aspect. Figure 5 schematically depicts a method according to an exemplary embodiment. The method is of handling communication in a Sidelink Relay network, including the Remote UE and the Relay UE, the method comprising: at step 501, handling, by the Remote UE and / or the Relay UE, an error and / or a misconfiguration. The method may include any of the steps described with respect to the first aspect. Although a preferred embodiment has been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims and as described above. At least some of the example embodiments described herein may be constructed, partially or wholly, using dedicated special-purpose hardware. Terms such as ‘component’, ‘module’ or‘unit’ used herein may include, but are not limited to, a hardware device, such as circuitry in the form of discrete or integrated components, a Field Programmable Gate Array (FPGA) or Application Specific Integrated Circuit (ASIC), which performs certain tasks or provides the associated functionality. In some embodiments, the described elements may be configured to reside on a tangible, persistent, addressable storage medium and may be configured to execute on one or more processors. These functional elements may in some embodiments include, by way of example, components, such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables. Although the example embodiments have been described with reference to the components, modules and units discussed herein, such functional elements may be combined into fewer elements or separated into additional elements. Various combinations of optional features have been described herein, and it will be appreciated that described features may be combined in any suitable combination. In particular, the features of any one example embodiment may be combined with features of any other embodiment, as appropriate, except where such combinations are mutually exclusive. Throughout this specification, the term “comprising” or “comprises” means including the component(s) specified but not to the exclusion of the presence of others. Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and / or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and / or steps are mutually exclusive. Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features. The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

1. A method of handling communication in a Sidelink Relay network, including a Remote UE and a Relay UE, the method comprising:handling, by the Remote UE and / or the Relay UE, an error and / or a misconfiguration.

2. The method according to any previous claim, wherein handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises discarding, by the Remote UE, a packet received thereby if a UE ID of the packet does not match the ID of the Remote UE.

3. The method according to any previous claim, wherein handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises discarding, by the Remote UE, a packet received thereby if a bearer ID of the packet does not match a bearer for the Remote UE.

4. The method according to any previous claim, wherein handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises discarding, by the Relay UE, a packet received thereby if a UE ID of the packet is not included in a configuration table.

5. The method according to any previous claim, wherein handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises discarding, by the Relay UE, a packet received thereby if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet does not match a bearer included in the configuration table for the UE ID.

6. The method according to of claims 1 to 4, wherein handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises sending, by the Relay UE, a packet received thereby on a default channel if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet does not match a bearer included in the configuration table for the UE ID.

7. The method according to claim 6, wherein the default channel is a dedicated, pre-configured and / or configurable mapping between an RLC channel ID (i.e. the default channel) and one or more E2E bearer IDs.

8. The method according to any previous claim, wherein handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises sending, by the Relay UE, a packet received thereby on a channel selected based on prioritization if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a plurality of bearers included in the configuration table for the UE ID.

9. The method according to any previous claim, wherein handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises sending, by the Relay UE, a packet received thereby on a channel selected randomly if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a plurality of bearers included in the configuration table for the UE ID.

10. The method according to any previous claim, wherein handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises sending, by the Relay UE, a packet received thereby on a channel selected based on QoS requirements if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a plurality of bearers included in the configuration table for the UE ID.

11. The method according to any previous claim, wherein handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises selectively discarding, by the Relay UE, a packet received thereby if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a bearer included in the configuration table for the UE ID and if a determined egress link is in RLF or congested.

12. The method according to any previous claim, wherein handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises discarding, by the Relay UE, a packet received thereby if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a bearer included in the configuration table for the UE ID and if the Relay UE is to change its serving cell, for example due to RRCReconfiguration.

13. The method according to any previous claim, wherein handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises removing, by the Relay UE, a configuration table upon Uu RLF detection / notification or upon reception of an RRCReconfiguration including the reconfigurationWithSync.

14. The method according to any previous claim, wherein handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises forwarding, by the Relay UE, a buffered packet before removing, by the Relay UE, a configuration table.

15. The method according to any previous claim, wherein handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises re-routing via a different Remote UE, by the Relay UE, a packet received thereby if a UE ID of the packet is included in a configuration table and if a bearer ID of the packet matches a bearer included in the configuration table for the UE ID and if a determined egress link is in RLF or if the Relay UE is to change its serving cell, for example due to RRCReconfiguration.

16. The method according to any previous claim, wherein handling, by the Remote UE and / or the Relay UE, the error and / or the misconfiguration comprises releasing, at the Relay UE, a SRAP entity.

517. A Sidelink. Relay network, including a Remote UE and a Relay UE, configured to implement a method according to any of claims 1 to 16.