Method of path selection in PDCP layer to support multipath configuration
Methods are provided to support path selection for a remote UE configured with multipath in a UE-to-network relay. A direct path or an indirect path is set as the primary path. Side information of the indirect path is considered for path selection. A remote UE can select a suitable path by utilizing the side information for path selection to check whether an indirect path can fulfill the QoS requirement of arriving UL traffic. In a network-controlled path selection, the base station can request UE to send side information. The base station indicates the selected path or the change of primary path to the UE via explicit signaling. Each path is identified by a path ID. The path indication is in a granularity of per radio bearer, per QoS flow, per logical channel, or per logical channel group.
1 . A method comprising:
identifying a traffic type or requirement of arriving traffic by a remote User Equipment (UE), wherein the remote UE is configured with multipath comprising a direct path to a base station and an indirect path to the base station via a relay UE, and wherein a primary path is selected from the direct path and the indirect path;
obtaining, by the remote UE, link information of the direct path and side information of the indirect path, wherein the side information comprises metrics of sidelink (SL) or metrics of WiFi between the remote UE and the relay UE, and wherein the metrics of sidelink comprises one of a SL reference signal received power (RSRP), SL signal to interference and noise ratio (SINR), SL channel busy ratio (CBR), and a transmission latency; and
applying, by the remote UE, path selection rules to select a path for traffic forwarding based at least on the traffic type or requirement, the link information, and the side information.
2 . The method of claim 1 , wherein the selected path is in a granularity of per radio bearer, per QoS flow, per logical channel (LCH), or per logical channel group (LCG).
3 . The method of claim 1 , wherein a path selection rule is that packets belonging to one of a signal radio bearer (SRB), a PDCP control PDU, and URLLC traffic are forwarded to the primary path.
4 . The method of claim 1 , wherein the primary path or the direct path is selected if the data volume in a PDCP buffer is below a data volume threshold.
5 . The method of claim 1 , wherein the UE sends a path indication of the selected path to the relay UE or the base station, and wherein the path indication is carried by a radio resource control (RRC) signaling message or a MAC control element (CE).
6 . The method of claim 5 , wherein the path indication comprises a path ID of the selected path.
7 . A remote User Equipment (UE) comprising:
a control circuit that identifies a traffic type or requirement of arriving traffic, wherein the remote UE is configured with multipath comprising a direct path to a base station and an indirect path to the base station via a relay UE, and wherein a primary path is selected from the direct path and the indirect path;
a receiver that obtains link information of the direct path and side information of the indirect path, wherein the side information comprises metrics of sidelink (SL) or metrics of WiFi between the remote UE and the relay UE, and wherein the metrics of sidelink comprises one of a SL reference signal received power (RSRP), SL signal to interference and noise ratio (SINR), SL channel busy ratio (CBR), and a transmission latency; and
a path selection circuit that applies path selection rules to select a path for traffic forwarding based at least on the traffic type or requirement, the link information, and the side information.
8 . The UE of claim 7 , wherein the selected path is in a granularity of per radio bearer, per QoS flow, per logical channel (LCH), or per logical channel group (LCG).
9 . The UE of claim 7 , wherein a path selection rule is that packets belonging to one of a signal radio bearer (SRB), a PDCP control PDU, and URLLC traffic are forwarded to the primary path.
10 . The UE of claim 7 , wherein the primary path or the direct path is selected if the data volume in a PDCP buffer is below a data volume threshold.
11 . The UE of claim 7 , further comprising:
a transmitter that sends a path indication of the selected path to the relay UE or the base station, wherein the path indication is carried by a radio resource control (RRC) signaling message or a MAC control element (CE).
12 . The UE of claim 11 , wherein the path indication comprises a path ID of the selected path.
13 . A method comprising:
receiving uplink information and side information from a remote UE or from a relay UE by a base station, wherein the remote UE is configured with multipath comprising a direct path to the base station and an indirect path to the base station via a relay UE, and wherein a primary path is selected from the direct path and the indirect path, wherein the side information comprises metrics of sidelink (SL) or metrics of WiFi between the remote UE and the relay UE, and wherein the metrics of sidelink comprises one of a SL reference signal received power (RSRP), SL signal to interference and noise ratio (SINR), SL channel busy ratio (CBR), and a transmission latency;
performing, by the base station, dynamic primary path change based on the uplink information and the side information, wherein the base station selects a path for the remote UE for transmitting uplink traffic; and
sending, by the base station, a path indication of the selected path to the remote UE, wherein the path indication is carried by an RRC message, a DL MAC control element, or a PHY layer control signaling.
14 . The method of claim 13 , further comprising:
requesting the remote UE or the relay UE to send the side information to the network entity.