WO2021188852A1

WO2021188852A1 - Ue-based energy efficient uplink data split in dual connectivity

Info

Publication number: WO2021188852A1
Application number: PCT/US2021/023069
Authority: WO
Inventors: Faranaz SABOURI-SICHANI; Daniela Laselva
Original assignee: Nokia Technologies Oy; Nokia Of America Corporation
Priority date: 2020-03-20
Filing date: 2021-03-19
Publication date: 2021-09-23

Abstract

In an aspect of the present disclosure, a method includes computing at least one uplink transmit power level required toward each of a master node and a secondary node; determining a total amount of data in a buffer requiring transmission; comparing the total amount of data to a preselected data splitting threshold; when the total amount of data does not exceed the preselected data splitting threshold, sending the total amount of data to the one of the master node and the secondary node having a smaller required uplink transmit power level; and, when the total amount of data exceeds the preselected data splitting threshold, preparing a buffer status report and providing the buffer status report for a logical channel to a network including the master node and the secondary node, the buffer status report including the total amount of data and a split of the total amount of data into two portions based on the at least one uplink transmit power level required toward the master node and the at least one uplink transmit power level required toward the secondary node.

Description

UE-BASED ENERGY EFFICIENT UPLINK DATA SPLIT IN DUAL

CONNECTIVITY

TECHNICAL FIELD

The present disclosure is related to 5G new radio, and, in particular, to a 5G low-latency access concept. More specifically, the present disclosure relates to a UE power saving optimization in MR-DC use cases.

BACKGROUND

The present disclosure relates to 5G communication systems, and, in particular, relates to UE power saving in NR. To date, power saving deployment for a single NR connection has been considered. However, it has been agreed that power saving improvements in dual connectivity (DC) would also be viable to consider, particularly in E-UTRA NR Dual Connectivity (EN-DC).

UE Power Saving:

It has been suggested that the UE can utilize different power saving schemes as specified in 3GPP TR 38.840 (“3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR; Study on UE Power Saving (Release 16”) whenever the conditions allow. In general, the UE power consumption reduction will utilize a wide range of techniques to allow UE implementations which can operate with reduced power consumption. The proposed schemes which are very likely to be introduced in 3GPP Release 16 (Rel-16) are listed below.

- UE adaptation to the traffic and power consumption characteristic.

- UE assistance for power saving.

- Power saving signal/channel/procedure for triggering adaptation to UE power consumption.

- Power consumption reduction in RRM (radio resource management) measurements.

The agreed power saving schemes focus on control plane communication between the UE and NB while data plane is kept out of the discussion. Dual Connectivity:

A number of 5G architecture deployment options are defined in 3GPP for independent migration of the access and core networks. The present disclosure will be applicable for any dual connectivity deployment option; however, the examples with details in the present disclosure are based on option 3 (EPC + LTE-assisted 5G NR (EN- DQ), MR-DC with EPC (EN-DC), and the NR-NR dual connectivity (NR-NR DC) among MR-DC options with NGC as shown in Figure 4, which illustrates control and user plane interfaces for EN-DC and NR-NR DC.

In the Multi-RAT Dual Connectivity (MR-DC), in addition to the RRC (radio resource control) connection towards the master node (MN), a mobile device has a second RRC termination at the secondary node (SN). From the perspective of a user equipment (UE), two cell groups are visible, that is, the master and secondary cell groups (MCG and SCG), and each cell group contains a primary cell called PCell (for MCG) and a primary SCell, PSCell, (for SCG), as in the legacy DC framework.

In MR-DC, the master node (MN), belonging to the MCG, and secondary node (SN), belonging to the SCG, operate as independently from one another as possible. Basically, each gNB, or eNB, owns its radio resources and is primarily responsible for allocating radio resources to the UE independently. However, the MN is responsible for maintaining the RRC connection state transitions, handling the connection setup/release, and initiating the first-time secondary node addition, that is, the DC setup. Any information exchange/coordination between MN and SN takes place via the X2/Xn interface, as shown in Figure 4.

In DC, the network achieves per-user throughput increase by aggregating radio resources from two NBs. In the uplink, the UE uses only one of the two links for packet data convergence protocol (PDCP) protocol data unit (PDU) transmission as long there is no need for large data amount. Note switching between MN and SN for uplink data requires layer 3 messaging, that is, RRCConnectionReconfiguration. It is up to the master NB to decide whether to utilize both uplink (UL) legs and how to split data of a split data radio bearer (DRB) across the two radio link control (RLC) entities.

Basically, how to perform data transmission on the split DRBs is decided by the MN based on its implementation and related commands being provided to the UE by RRC parameters carrying PDCP configuration. These include two main parameters: As long as the UL data buffer size is below a given limit (defined by the parameter ul- DataSplitThreshold), the UL transmission will use only one RLC entity, namely, the primary RLC entity at the MN ( see 3 GPP TS 36.331 and 3 GPP TS 38.331).

- The primary entity can be reconfigured, that is, changed, using the parameter ul- DataSplitDRB- ViaSCG (see 3 GPP TS 36.331).

- If the UE’s UL data buffer size (PDCP and RLC buffers) exceeds the threshold ul- DataSplitThreshold, the data should be split between the two nodes (see 3GPP TS 36.331 and 3GPPTS 38.331).

The UE will then - depending on its data buffer size - transmit on MCG, SCG, or apply split bearer based on the italicized rules below (see Section 5.2, 3GPP TS 38.323):

“When submitting a PDCP (data) PDU to lower layer, the transmitting PDCP entity shall:

- if the transmitting PDCP entity is associated with one RLC entity: o submit the PDCP PDU to the associated RLC entity;

- else, if the transmitting PDCP entity is associated with two RLC entities: o if the PDCP duplication is activated:

^■ if the PDCP PDU is a PDCP Data PDU:

- duplicate the PDCP Data PDU and submit the PDCP Data PDU to both associated RLC entities;

* else

- submit the PDCP Control PDU to the primary RLC entity; o else

* if the two associated RLC entities belong to the different Cell Groups; and

¹ if the total amount of PDCP data volume and RLC data volume pending for initial transmission (as specified in 3GPP TS 38.322 (“3rd Generation Partnership Project; Technical Specification Group Radio Access Network; NR;

Radio Link Control (RLC) protocol specification”) in the two associated RLC entities is equal to or larger than ul- PataSOlitThreshold: - submit the PDCP PDU to either the primary RLC entity or the secondary RLC entity;

^■ else (less than threshold => one link):

- submit the PDCP PDU to the primary RLC entity. "

The choice of primary and secondary RLC entity as well as the data split ratio is based on the MN decision and up to NW implementation. At SN Addition preparation, MN may ask the SN to provide additional resources to the UE. To guide the resource assignments at SN, the MN splits the total guaranteed bit rate (GBR) target of the split DRB in two portions and asks SN to provide one portion of the GBR that the MN cannot provide by itself as illustrated in Figure 5.

- The GBR split is typically based on MN’s physical resource block (PRB) load.

- The consequent GBR distribution between MN and SN is used for determining UL grants by MN and SN.

The aim of UL data bearer split is to increase the UL throughput for the user, as it enables the UE to utilize radio resources from two NBs. It also provides better user experience in cases where one NB (cell group) link is overloaded or the link towards one NB is degraded. The UL bearer split may also help in network load balancing; hence, MN may calculate the data split ratio based on radio conditions and network load in MCG and SCG similar to downlink bearer splitting. Then, the MN and SN should be able to ensure indirectly that the UE uses the calculated data split ratio, by sending appropriate UL (dynamic) scheduling grants.

Currently, at the initial SN Addition, the MN splits the total GBR target associated to the DRB, requesting SN to provide the portion MN cannot support by itself, hence, typically based on MN’s PRB load. After the DC setup is completed, each node can determine the UL grants based on the requested GBR and the buffer status reporting (BSR) received by the UE. It is noted that the two radio links towards MN and SN will have their independent power control running.

The UL power level of each link is controlled by the NW separately through uplink power control based on legacy mechanisms, and is directly proportional to the path loss (PL) between the UE and NB. For instance, the open-loop power control configuration for PUSCH/SRS, Po, a, combined with the UE-estimated PL, is linked to SRS resource indicator (SRI) which indicates the number of configured SRS resources in the SRS resource set for a PUSCH beam (see 3GPP TS 38.213). The control of the UE transmit power is done by the network via transmit power control (TPC) commands; hence, the UE has the knowledge about the requested UL transmit power to each node.

The required UL transmitter (Tx) power may be higher towards MN than SN or vice versa depending on the UE’s radio link condition, mainly, the path loss for the selected beam due to different distances between the UE and each NB. This difference can be up to several dBs. As an example, a UE in EN-DC mode between a macro LTE eNB and an NR small cell may be in proximity of the NR small cell and, therefore, it may be beneficial to transmit the dominant part of UL data DRBs over the NR SN.

Although, the power control algorithm at each node would independently ensure that the uplink transmit powers used for transmissions towards each node are adequate, no explicit consideration of the uplink transmit power is taken when making the splitting decision in the prior art.

However, the dominating power consumption at the UE is when it is transmitting due to significant high current consumption in power amplifiers. This is further directly proportional to the absolute UL transmit power, and the_^UL transmit power is directly proportional to the path loss. As a UE can have quite different distances to the two nodes, it is expected that the corresponding path loss and, hence, the requested UL transmit power can differ by several dBs between the two nodes. The difference in transmit power between the two nodes may also be due to different operating carrier frequencies. Therefore, considering the requested power level toward MN and SN when deciding the primary RLC entity as well as the relative data split across MN and SN would improve UE power saving.

Table 1 below, illustrating simulation results of averaged power in units/slots for some DL and UL examples, quantifies the impact of UE power consumption during UL transmission as function of the UL transmit power. In particular, Table 1 contains examples showing how the average consumed power by the UE depends on the uplink transmit power of the used link. The examples are generated using the NR UE power consumption model as defined in 3GPP TS 38.840. The model applies time division duplex (TDD), 30 kHz SCS and 100 MHz BW. It can be observed that using a 23 dBm link instead of a 0 dBm link increases the average power consumption per slot by 200% using a single UL component carrier and single antenna and an increase of 157% with a single UL component carrier and two antennas (2x2 UL MIMO). Table 1

Rel-13 LTE supports uplink bearer split, building on top of the downlink split-bearer architecture with aggregation of data links at PDCP layer, allowing utilization of uplink radio resources on both MCG and SCG links simultaneously for a data bearer. The same framework was inherited by NR. Currently, the distribution of UL data bearers’ split over MCG and SCG is up to network implementation and can be based on the buffer status report (BSR) and configured guaranteed bit rate (GBR) at each node. In uplink bearer split scenarios, the BSR is sent from the UE to the gNB/eNB to indicate the amount of pending data in the uplink buffer. When the UE is configured with SCG, two medium access control (MAC) entities are configured to the UE: one for the MCG and one for the SCG.

Figure 6 illustrates an exemplary message sequence chart based on the legacy UL data split in dual connectivity. It can be observed that the data available for transmission of a split bearer will be equally reflected in the two equal BSRs, which are sent towards the MCG and SCG.

In contrast, in the present disclosure the BSR reporting in DC scenarios is manipulated, such that each node knows more information than just the total BSR as in the legacy scheme. Split DRB (DC uplink, data plane): as shown in Figure 6, a buffer size based threshold is used to trigger the use of secondary leg, and configuration of the primary leg for data plane is according to the following: ul-DataSplitThreshold (see 3 GPP TS 36.331 and 3 GPP TS 38.331]

Indicates the threshold value for uplink data split operation specified in 3GPP TS 36.323 (“3rd Generation Partnership Project;

Technical Specification Group Radio Access Network; NR; Packet Data Convergence Protocol”). Value blOO means 100 Bytes, b200 means 200 Bytes and so on, E-UTRAN only configures this field for split DRBs, ul-DataSplitDRB-ViaSCG (see 3 GPP TS 36.331)

Indicates whether the UE shall send PDCP PDUs via SCG as specified in 3 GPP TS 36.323. E-UTRAN only configures the field, that is, indicates value TRUE, for split DRBs. For PDCP duplication, if this field is set to TRUE, the primary RLC entity is SCG RLC entity and the secondary RLC entity is MCG RLC entity. If this field is not configured or set to FALSE, the primary RLC entity is MCG RLC entity and the secondary RLC entity is SCG RLC entity,

Currently, the primary link and when the data should be split is controlled by the network in a semi-static fashion; the relevant parameters are provided via RRC signaling. The present disclosure builds upon both concepts and extends them making the data splitting based on power efficiency and allowing a fast change of the primary leg based on power-efficiency considerations.

SUMMARY

In a first aspect of the present disclosure, a method comprises: computing at least one uplink transmit power level required toward each of a master node and a secondary node; determining a total amount of data in a buffer requiring transmission; comparing the total amount of data to a preselected data splitting threshold; when the total amount of data does not exceed the preselected data splitting threshold, sending the total amount of data to the one of the master node and the secondary node having a smaller required uplink transmit power level; and when the total amount of data exceeds the preselected data splitting threshold, preparing a buffer status report and providing the buffer status report for a logical channel to a network including the master node and the secondary node, the buffer status report including the total amount of data and a split of the total amount of data into two portions based on the at least one uplink transmit power level required toward the master node and the at least one uplink transmit power level required toward the secondary node.

The split of the total amount of data into two portions may be in inverse proportion to the ratio between the required uplink transmit power levels. The method may further comprise: sending the larger of the two portions of the total amount of data to the one of the master node and the secondary node having a lower required uplink transmit power level,

In a second aspect of the present disclosure, an apparatus comprises: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured, with the at least one processor, to cause the apparatus to perform the following: compute at least one uplink transmit power level required toward each of a master node and a secondary node; determine a total amount of data in a buffer requiring transmission; compare the total amount of data to a preselected data splitting threshold; when the total amount of data does not exceed the preselected data splitting threshold, send the total amount of data to the one of the master node and the secondary node having a smaller required uplink transmit power level; and when the total amount of data exceeds the preselected data splitting threshold, prepare a buffer status report and provide the buffer status report for a logical channel to a network including the master node and the secondary node, the buffer status report including the total amount of data and a split of the total amount of data into two portions based on the at least one uplink transmit power level required toward the master node and the at least one uplink transmit power level required toward the secondary node.

The split of the total amount of data into two portions may be in inverse proportion to the ratio between the required uplink transmit power levels.

The at least one memory and the computer program code may be further configured, with the at least one processor, to cause the apparatus to perform the following: send the larger of the two portions of the total amount of data to the one of the master node and the secondary node having a lower required uplink transmit power level.

In a third aspect of the present disclosure, an apparatus comprises: means for computing at least one uplink transmit power level required toward each of a master node and a secondary node; means for determining a total amount of data in a buffer requiring transmission; means for comparing the total amount of data to a preselected data splitting threshold; means for sending the total amount of data to the one of the master node and the secondary node having a smaller required uplink transmit power level, when the total amount of data does not exceed the preselected data splitting threshold; and means for preparing a buffer status report and for providing the buffer status report for a logical channel to a network including the master node and the secondary node, the buffer status report including the total amount of data and a split of the total amount of data into two portions based on the at least one uplink transmit power level required toward the master node and the at least one uplink transmit power level required toward the secondary node, when the total amount of data exceeds the preselected data splitting threshold.

The apparatus may further comprise: means for sending the larger of the two portions of the total amount of data to the one of the master node and the secondary node having a lower required uplink transmit power level.

In a fourth aspect of the present disclosure, a computer program product comprises a non-transitory computer-readable storage medium bearing computer program code embodied therein for use with a computer, the computer program code comprising code for performing: computing at least one uplink transmit power level required toward each of a master node and a secondary node; determining a total amount of data in a buffer requiring transmission; comparing the total amount of data to a preselected data splitting threshold; when the total amount of data does not exceed the preselected data splitting threshold, sending the total amount of data to the one of the master node and the secondary node having a smaller required uplink transmit power level; and, when the total amount of data exceeds the preselected data splitting threshold, preparing a buffer status report and providing the buffer status report for a logical channel to a network including the master node and the secondary node, the buffer status report including the total amount of data and a split of the total amount of data into two portions based on the at least one uplink transmit power level required toward the master node and the at least one uplink transmit power level required toward the secondary node.

The computer program code may also comprise code for performing: sending the larger of the two portions of the total amount of data to the one of the master node and the secondary node having a lower required uplink transmit power level.

In a fifth aspect of the present disclosure, a method comprises: receiving a buffer status report including the total amount of data and an indication of a split of the total amount of data into two portions to be accommodated by each of a first network node and a second network node; allocating the required uplink radio resources to the user equipment for uplink transmission of a first portion of data to the first network node; and when allocating all of the required uplink resources for uplink transmission of the first portion of data to the first network node is not possible, identifying a third portion of data, the third portion of data being a remaining part of the first portion of data, and communicating with the second network node to request the second network node to allocate the required uplink radio resources to the user equipment for uplink transmission of the second portion of data plus the third portion of data.

The method may further comprise: allocating the required uplink resources to accommodate the larger of the two portions of data when the at least one uplink transmit power level of the user equipment towards the first network node is lower than that of the second network node.

In a sixth aspect of the present disclosure, an apparatus comprises: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured, with the at least one processor, to cause the apparatus to perform the following: receive a buffer status report including the total amount of data and an indication of a split of the total amount of data into two portions to be accommodated by each of a first network node and a second network node; allocate the required uplink radio resources to the user equipment for uplink transmission of a first portion of data to the first network node; and when allocating all of the required uplink resources for uplink transmission of the first portion of data to the first network node is not possible, identify a third portion of data, the third portion of data being a remaining part of the first portion of data, and communicate with the second network node to request the second network node to allocate the required uplink radio resources to the user equipment for uplink transmission of the second portion of data plus the third portion of data.

The at least one memory and the computer program code may be further configured, with the at least one processor, to cause the apparatus to perform the following: allocate the required uplink resources to accommodate the larger of the two portions of data when the at least one uplink transmit power level of the user equipment towards the first network node is lower than that of the second network node.

In a seventh aspect of the present disclosure, an apparatus comprises: means for receiving a buffer status report including the total amount of data and an indication of a split of the total amount of data into two portions to be accommodated by each of a first network node and a second network node; means for allocating the required uplink radio resources to the user equipment for uplink transmission of a first portion of data to the first network node; and means for identifying a third portion of data, the third portion of data being a remaining part of the first portion of data, and for communicating with the second network node to request the second network node to allocate the required uplink radio resources to the user equipment for uplink transmission of the second portion of data plus the third portion of data, when allocating all of the required uplink resources for uplink transmission of the first portion of data to the first network node is not possible.

The apparatus may further comprise: means for allocating the required uplink resources to accommodate the larger of the two portions of data when the at least one uplink transmit power level of the user equipment towards the first network node is lower than that of the second network node.

In an eighth aspect of the present disclosure, a computer program product comprises a non-transitory computer-readable storage medium bearing computer program code embodied therein for use with a computer, the computer program code comprising code for performing: receiving a buffer status report including the total amount of data and an indication of a split of the total amount of data into two portions to be accommodated by each of a first network node and a second network node; allocating the required uplink radio resources to the user equipment for uplink transmission of a first portion of data to the first network node; and, when allocating all of the required uplink resources for uplink transmission of the first portion of data to the first network node is not possible, identifying a third portion of data, the third portion of data being a remaining part of the first portion of data, and communicating with the second network node to request the second network node to allocate the required uplink radio resources to the user equipment for uplink transmission of the second portion of data plus the third portion of data.

The computer program code may also comprise code for performing: allocating the required uplink resources to accommodate the larger of the two portions of data when the at least one uplink transmit power level of the user equipment towards the first network node is lower than that of the second network node.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other aspects of these teachings are made more evident in the following detailed description, when read in conjunction with the attached drawing figures. Figure 1 shows a simplified block diagram of certain apparatus in which the subject matter of the present disclosure may be practiced.

Figures 2 and 3 show an example of New Radio (NR) architecture having the 5G core (5GC) and the NG-RAN.

Figure 4 illustrates control and user plane interfaces for EN-DC and NR-

NR DC.

Figure 5 illustrates GBR configuration/split across MN and SN at SN addition.

Figure 6 illustrates an exemplary message sequence chart for uplink data split in legacy dual connectivity.

Figure 7 is a schematic illustration of an exemplary embodiment in which a UL DRB data split in Dual Connectivity is based on requested UL transmit power.

Figure 8 is a message sequence chart for the exemplary embodiment (UE- based) when the data size requires UL data split.

Figure 9 is a flow chart for an exemplary embodiment of the present disclosure.

Figure 10 is a flow chart illustrating a method performed by a user equipment in accordance with the present disclosure.

Figure 11 is a flow chart illustrating a method performed by a network node in accordance with the present disclosure.

DETAILED DESCRIPTION

Figure 1 is a block diagram of one possible and non-limiting example in which the subject matter of the present disclosure may be practiced. A user equipment

(UE) 110, radio access network (RAN) node 170, and network element(s) 190 are illustrated. In the example of Figure 1, the user equipment (UE) 110 is in wireless communication with a wireless network 100. A UE is a wireless device, typically mobile, that can access the wireless network. The UE 110 includes one or more processors 120, one or more memories 125, and one or more transceivers 130 interconnected through one or more buses 127. Each of the one or more transceivers 130 includes a receiver, Rx, 132 and a transmitter, Tx, 133. The one or more buses 127 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, and the like, The one or more transceivers 130 are connected to one or more antennas 128. The one or more memories 125 include computer program code 123, The UE 110 includes a module 140, comprising one of or both parts 140-1 and/or 140-2, which may be implemented in a number of ways. The module 140 may be implemented in hardware as module 140-1, such as being implemented as part of the one or more processors 120. The module 140-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, the module 140 may be implemented as module 140-2, which is implemented as computer program code 123 and is executed by the one or more processors 120. For instance, the one or more memories 125 and the computer program code 123 may be configured, with the one or more processors 120, to cause the user equipment 110 to perform one or more of the operations as described herein. The UE 110 communicates with RAN node 170 via a wireless link 111.

The RAN node 170 in this example is a base station that provides access by wireless devices, such as the UE 110, to the wireless network 100. The RAN node

170 may be, for example, a base station for 5G, also called New Radio (NR). In 5G, the

RAN node 170 may be an NG-RAN node, which is defined as either a gNB or an ng- eNB. A gNB is a node providing NR user plane and control-plane protocol terminations toward the UE, and connected via the NG interface to a 5GC, such as, for example, the network element(s) 190. The ng-eNB is a node providing E-UTRA user plane and control plane protocol terminations towards the UE, and connected via the NG interface to the 5GC. The NG-RAN node may include multiple gNBs, which may also include a centralized unit (CU) (gNB-CU) 196 and distributed unit(s) (DUs) (gNB-DUs), of which

DU 195 is shown. Note that the DU may include or be coupled to and control a radio unit

(RU). The gNB-CU is a logical node hosting RRC, SDAP and PDCP protocols of the gNB or RRC and PDCP protocols of the en-gNB that controls the operation of one or more gNB-DUs. The gNB-CU terminates the FI interface connected with the gNB-DU.

The FI interface is illustrated as reference 198, although reference 198 also illustrates a link between remote elements of the RAN node 170 and centralized elements of the RAN node 170, such as between the gNB-CU 196 and the gNB-DU 195. The gNB-DU is a logical node hosting RLC, MAC and PHY layers of the gNB or ng-eNB, and its operation is partly controlled by gNB-CU. One gNB-CU supports one or multiple cells. One cell is supported by only one gNB-DU. The gNB-DU terminates the FI interface 198 connected with the gNB-CU. Note that the DU 195 is considered to include the transceiver 160, for example, as part of a RU, but some examples of this may have the transceiver 160 as part of a separate RU, for example, under control of and connected to the DU 195. The RAN node 170 may also be an eNB (evolved NodeB) base station, for LTE (long term evolution), or any other suitable base station or node.

The RAN node 170 includes one or more processors 152, one or more memories 155, one or more network interfaces (N/W I/F(s)) 161, and one or more transceivers 160 interconnected through one or more buses 157. Each of the one or more transceivers 160 includes a receiver, Rx, 162 and a transmitter, Tx, 163. The one or more transceivers 160 are connected to one or more antennas 158. The one or more memories 155 include computer program code 153. The CU 196 may include the processor(s) 152, memories 155, and network interfaces 161. Note that the DU 195 may also contain its own memory/memories and processor(s), and/or other hardware, but these are not shown.

The RAN node 170 includes a module 150, comprising one of or both parts 150-1 and/or 150-2, which may be implemented in a number of ways. The module 150 may be implemented in hardware as module 150-1, such as being implemented as part of the one or more processors 152. The module 150-1 may be implemented also as an integrated circuit or through other hardware such as a programmable gate array. In another example, module 150 may be implemented as module 150-2, which is implemented as computer program code 153 executed by the one or more processors 152. For instance, the one or more memories 155 and the computer program code 153 are configured, with the one or more processors 152, to cause the RAN node 170 to perform one or more of the operations as described herein, Note that the functionality of the module 150 may be distributed, such as being distributed between the DU 195 and the CU 196, or be implemented solely in the DU 195.

The one or more network interfaces 161 communicate over a network such as via the links 176 and 131. Two or more gNBs 170 may communicate using, e.g., link 176. The link 176 may be wired or wireless or both and may implement, for example, an Xn interface for 5G, an X2 interface for LTE, or other suitable interface for other standards.

The one or more buses 157 may be address, data, or control buses, and may include any interconnection mechanism, such as a series of lines on a motherboard or integrated circuit, fiber optics or other optical communication equipment, wireless channels, and the like. For example, the one or more transceivers 160 may be implemented as a remote radio head (RRH) 195 for LTE or a distributed unit (DU) 195 for gNB implementation for 5G, with the other elements of the RAN node 170 possibly being physically in a different location from the RRH/DU, and the one or more buses 157 could be implemented in part as, for example, fiber optic cable or other suitable network connection to connect the other elements (e.g., a centralized unit (CU), gNB-CU) of the RAN node 170 to the RRH/DU 195. Reference 198 also indicates those suitable network link(s).

It is noted that description herein indicates that “cells” perform functions, but it should be clear that equipment which forms the cell will perform the functions. The cell makes up part of a base station. That is, there can be multiple cells per base station. For example, there could be three cells for a single carrier frequency and associated bandwidth, each cell covering one-third of a 360° area so that the single base station’s coverage area covers an approximate oval or circle. Furthermore, each cell can correspond to a single carrier and a base station may use multiple carriers. So if there are three 120° cells per carrier and two carriers, then the base station has a total of six cells.

The wireless network 100 may include a network element or elements 190 that may include core network functionality, and which provides connectivity via a link or links 181 with a further network, such as a telephone network and/or a data communications network (e.g., the Internet). Such core network functionality for 5G may include access and mobility management function(s) (AMF(S)) and/or user plane functions (UPF(s)) and/or session management function(s) (SMF(s)). Such core network functionality for LTE may include MME (Mobility Management Entity)/SGW (Serving Gateway) functionality. These are merely exemplary functions that may be supported by the network element(s) 190, and note that both 5G and LTE functions might be supported. The RAN node 170 is coupled via a link 131 to a network element 190. The link 131 may be implemented as, for example, an NG interface for 5G, or an SI interface for LTE, or other suitable interface for other standards. The network element 190 includes one or more processors 175, one or more memories 171, and one or more network interfaces (N/W I/F(s)) 180, interconnected through one or more buses 185. The one or more memories 171 include computer program code 173. The one or more memories 171 and the computer program code 173 are configured, with the one or more processors 175, to cause the network element 190 to perform one or more operations.

The wireless network 100 may implement network virtualization, which is the process of combining hardware and software network resources and network functionality into a single, software-based administrative entity, a virtual network.

Network virtualization involves platform virtualization, often combined with resource virtualization. Network virtualization is categorized as either external, combining many networks, or parts of networks, into a virtual unit, or internal, providing network-like functionality to software containers on a single system. Note that the virtualized entities that result from the network virtualization are still implemented, at some level, using hardware such as processors 152 or 175 and memories 155 and 171, and also such virtualized entities create technical effects.

The computer-readable memories 125, 155, and 171 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, flash memory, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The computer-readable memories 125, 155, and 171 may be means for performing storage functions. The processors 120, 152, and 175 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi-core processor architecture, as nonlimiting examples. The processors 120, 152, and 175 may be means for performing functions, such as controlling the UE 110, RAN node 170, and other functions as described herein.

In general, the various embodiments of the user equipment 110 can include, but are not limited to, cellular telephones such as smart phones, tablets, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, tablets with wireless communication capabilities, as well as portable units or terminals that incorporate combinations of such functions.

Figures 2 and 3 show an example of New Radio (NR) architecture having the 5G core (5GC) and the NG-RAN. The base stations gNB are coupled to the 5GC by the interface to core NGs, and the gNBs are coupled to each other by the inter-base station interface Xn.

In the present disclosure, there is introduced a UE power-saving optimization in MR-DC use cases by considering the requested UL transmit power over each radio link in the decision of the DRB’s data distribution between two nodes in case of UL data split. This is achieved by adapting the UL radio resource allocations to the UE from each node based on the UL transmit power to MN and to SN, aided by UE assistance.

Essentially, the disclosure allows the UL DRB’s data to be transmitted primarily over the most power-efficient uplink radio link, that is, the link with lowest requested UL transmit power, while still letting the less power-efficient radio link to contribute to the data delivery in order to reduce the total time for completing the transmissions. That is to say, whenever a split DRB is needed to address higher required throughput, the data split should consider transmitting the maximum portion of data over the most power-efficient radio link and transmit only the remaining portion over the least power efficient radio link. As a result, the total UL transmit power will be minimized, thereby achieving a UE power saving.

The proposed implementation comprising the main features and steps of the present disclosure is summarized in the following and is further detailed below. An exemplary embodiment is based on UE implementation with standard impact, that is, allowing UE to change the decision on the primary leg as well as new UE operation related to BSR.

• When the BSR does not exceed the data splitting threshold, ul-

DataSplitThreshold:

^■ the UE re-evaluates the primary leg based on the UL transmit power required for data transmission towards MN and SN, selecting the most power-efficient leg for the transmission of the total BSR (it is allowed to change the primary link configured by the network)

• When the BSR exceeds the data splitting threshold, ul-DataSplitThreshold:

^■ The UE splits the total BSR in two distinct BSRs and calculates the “node- specific” BSRs by splitting its total BSR according to the requested power from each node.

^■ UE informs the corresponding “node-specific” BSR values to each node along with the total BSR.

^■ Each node will then allocate UL radio resources to the UE based on the received “node-specific” BSR and on other local information such as PRB load, GBR, etc. Thus, the energy efficient split of BSR by the UE will then guide MN and SN to adjust their radio resource assignment to the UE accordingly, whenever feasible.

Exemplary embodiments of the present disclosure, then, propose that the data split of an uplink DRB between MN and SN be based on the requested UL transmit power PUL,MN and PUL.SN. In this way, the total uplink transmit power will be minimized, the total transmission time will be reduced, and power saving will be achieved. These can be realized by applying the following UE-based implementation.

This is illustrated in the schematic shown in Figure 7 and in the more detailed message sequence chart shown in Figure 8 for the case where BSR exceeds the data splitting threshold, ul-DataSplitThreshold, and includes the detailed steps described below:

1. The split of the total GBR of the DRB between MN and SN is decided by MN at the time the secondary node is added. The criteria for the split depend on NW implementation and is expected to be, mainly, based on the MN’s PRB load.

2. Each NB will have its independent power control toward the UE and the UE has information on the requested UL transmit power level, PUL.MN and PUL.SN, from each node.

3. Upon request for UL scheduling toward the NB, the UE calculates the UE- power efficient UL data split based on the PUL,MN / PUL,SN and calculates its BSR for MN (BSRMN) and BSR for SN (BSRSN) accordingly, that is, as a function of PUL.MN and PUL.SN with the aim of power efficiency splitting. The UE will then send BSRtotai and BSRMN to MN and BSRtotai and BSRSN to SN.

4. MN and SN will adopt the UL grants to their respective received BSR, hence, following the UE power saving based UL DRB split.

The UE informs the nodes about the amount of data it needs to transmit in its buffer status report (BSR). This disclosure proposes that the UE guide the two nodes for overall power-efficient resource allocations by sending two “node-specific” BSR reports, BSRMN and BSRSN, along with its total BSR, BSRtotai (refer to * in Figure 8). The “node-specific” BSR values scale BSR_totai with the optimal total UL transmit power, that is in accordance to the relative UL transmit powers, as shown in the non-limiting example of pseudo-algorithm for energy-efficient BSR calculation below: BSRtotai - BSRMN + BSRSN

BSRMN / BSRSN = PUL.SN / PUL,MN

BSRMN ⁼ Ceil (PUL.SN/ (PUL,MN + PUL,SN) * BSRtotai)

BSRSN ⁼ BSR_totai - BSRMN

At each node, the received “node-specific” BSR will be considered in combination with other existing parameters and factors for UL data split, for example, each node’s PRB load/capacity, GBR target, and Maximum Bit Rate (MBR)) to allocate UL data resources (refer to ** in Figure 8).

Maximum power saving based on the proposed method can be achieved in case each node is capable of allocating the resources based on the received “node- specific” BSR and will allocate the UL radio resources accordingly. In case the node is not capable of allocating UL data resources according to the “node-specific” BSR, due to limitation in, for example, its capacity, it can choose either of the options below (or potentially combine the two):

A. The node will allocate the maximum capable UL data resources and inform the other node with the remaining part which then can be provided by the other node. The resource allocation at MN and SN is thus based on exchange/alignment of BSR values across MN and SN over Xn/X2 interface without further UE involvement.

B. Each node responds to the UE with its maximum capacity in case the “node-specific” BSR exceeds this value, whereafter the UE can adjust the BSRs to the two nodes accordingly.

Figure 9 shows a flow chart for the embodiment of the proposal where the pseudo-algorithm used to calculate the BSR scaling as indicated by (*) and the following adaptation of power-efficient UL resource allocation at the NBs is indicated by (**).

Figure 10 is a flow chart illustrating a method performed by a user equipment in accordance with the present disclosure. According to the method, in block

1002 the user equipment computes at least one uplink transmit power level required toward each of a master node and a secondary node. In block 1004, the user equipment then determines a total amount of data in a buffer requiring transmission. In block 1006, the user equipment compares the total amount of data to a preselected data splitting threshold. In block 1008, when the total amount of data does not exceed the preselected data splitting threshold, the user equipment sends the total amount of data to the one of the master node and the secondary node having a smaller required uplink transmit power level. In block 1010, when the total amount of data exceeds the preselected data splitting threshold, the user equipment prepares a buffer status report and provides the buffer status report for a logical channel to a network including the master node and the secondary node, the buffer status report including the total amount of data and a split of the total amount of data into two portions based on the at least one uplink transmit power level required toward the master node and the at least one uplink transmit power level required toward the secondary node.

Figure 11 is a flow chart illustrating a method performed by a network node in accordance with the present disclosure. According to the method, in block 1102, the network node receives a buffer status report including the total amount of data and an indication of a split of the total amount of data into two portions to be accommodated by each of a first network node and a second network node. In block 1104, the network node allocates the required uplink radio resources to the user equipment for uplink transmission of a first portion of data to the first network node. Then, in block 1106, when allocating all of the required uplink resources for uplink transmission of the first portion of data to the first network node is not possible, the network node identifies a third portion of data, the third portion of data being a remaining part of the first portion of data, and communicates with the second network node to request the second network node to allocate the required uplink radio resources to the user equipment for uplink transmission of the second portion of data plus the third portion of data.

In general, the various exemplary embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software, which may be executed by a controller, microprocessor or other computing device, although the exemplary embodiments are not limited thereto.

While various aspects of the exemplary embodiments of this disclosure may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

It should thus be appreciated that at least some aspects of the exemplary embodiments of the disclosure may be practiced in various components, such as integrated circuit chips and modules, and that the exemplary embodiments of this disclosure may be realized in an apparatus that is embodied as an integrated circuit. The integrated circuit, or circuits, may comprise circuitry, as well as possibly firmware, for embodying at least one or more of a data processor or data processors, a digital signal processor or processors, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this disclosure.

Various modifications and adaptations to the foregoing exemplary embodiments of this disclosure may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. For example, while the exemplary embodiments have been described above in the context of advancements to the 5G NR system, it should be appreciated that the exemplary embodiments of this disclosure are not limited for use with only this one particular type of wireless communication system. The exemplary embodiments of the disclosure presented herein are explanatory and not exhaustive or otherwise limiting of the scope of the exemplary embodiments.

The following abbreviations may have been used in the preceding discussion: BSR Buffer Status Report BW Band Width CC Component Carrier DC Dual Connectivity DL Downlink DRB Data Radio Bearer eNB eNodeB (4G Base Station) EN-DC E-UTRA NR Dual Connectivity EPC Evolved Packet Core GBR Guaranteed Bit Rate gNB gNodeB (5G Base Station) IE Information Element LTE Long Term Evolution MAC Medium Access Control MBR Maximum Bit Rate MCG Master Cell Group

MN Master Node

MR-DC Multi-RAT Dual Connectivity

NB Node B NGC Next Generation Core NR New Radio (5G)

NR-DC NR-NR Dual Connectivity NW Network PCell Primary Cell PDCP Packet Data Convergence Protocol PDU Protocol Data Unit PHR Power Headroom Report PL Path Loss PRB Physical Resource Block PDCCH Physical Downlink Control Channel PDSCH Physical Downlink Shared Channel PUSCH Physical Uplink Shared Channel QoS Quality of Service RAT Radio Access Technology RLC Radio Link Control RRC Radio Resource Control RRM Radio Resource Management Rx Receiver SCell Secondary Cell SCG Secondary Cell Group SCS Sub Carrier Spacing SN Secondary Node SRI SRS Resource Indicator SRS Sounding Reference Signal TDD Time Division Duplex TPC Transmit Power Control Tx Transmitter UE User Equipment UL Uplink 3GPP 3^rd Generation Partnership Project

5G 5^th Generation

5GC 5^th Generation Core

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosed embodiments. As used herein, the singular forms “a”, “an”, and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising”, when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof,

The description of the present exemplary embodiments has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the embodiments in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the present disclosure. The embodiments were chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand the disclosure for various embodiments with various modifications as are suited to the particular use contemplated.

Various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings. However, any and all modifications of the teachings of this disclosure will still fall within the scope of the non-limiting embodiments thereof.

Although described in the context of particular embodiments, it will be apparent to those skilled in the art that a number of modifications and various changes to these teachings may occur. Thus, while the examples have been particularly shown and described with respect to one or more disclosed embodiments, it will be understood by those skilled in the art that certain modifications or changes may be made therein without departing from the scope of the disclosure as set forth above, or from the scope of the claims to follow.

Claims

WHAT IS CLAIMED IS:

1. A method comprising: computing at least one uplink transmit power level required toward each of a master node and a secondary node; determining a total amount of data in a buffer requiring transmission; comparing the total amount of data to a preselected data splitting threshold; when the total amount of data does not exceed the preselected data splitting threshold, sending the total amount of data to the one of the master node and the secondary node having a smaller required uplink transmit power level; and when the total amount of data exceeds the preselected data splitting threshold, preparing a buffer status report and providing the buffer status report for a logical channel to a network including the master node and the secondary node, the buffer status report including the total amount of data and a split of the total amount of data into two portions based on the at least one uplink transmit power level required toward the master node and the at least one uplink transmit power level required toward the secondary node.

2. The method as claimed in claim 1 , wherein the split of the total amount of data into two portions is in inverse proportion to the ratio between the required uplink transmit power levels.

3. The method as claimed in claim 1, further comprising: sending the larger of the two portions of the total amount of data to the one of the master node and the secondary node having a lower required uplink transmit power level.

4. An apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured, with the at least one processor, to cause the apparatus to perform the following: compute at least one uplink transmit power level required toward each of a master node and a secondary node; determine a total amount of data in a buffer requiring transmission; compare the total amount of data to a preselected data splitting threshold; when the total amount of data does not exceed the preselected data splitting threshold, send the total amount of data to the one of the master node and the secondaiy node having a smaller required uplink transmit power level; and when the total amount of data exceeds the preselected data splitting threshold, prepare a buffer status report and provide the buffer status report for a logical channel to a network including the master node and the secondary node, the buffer status report including the total amount of data and a split of the total amount of data into two portions based on the at least one uplink transmit power level required toward the master node and the at least one uplink transmit power level required toward the secondary node.

5. The apparatus as claimed in claim 4, wherein the split of the total amount of data into two portions is in inverse proportion to the ratio between the required uplink transmit power levels.

6. The apparatus as claimed in claim 4, wherein the at least one memory and the computer program code are further configured, with the at least one processor, to cause the apparatus to perform the following: send the larger of the two portions of the total amount of data to the one of the master node and the secondaiy node having a lower required uplink transmit power level.

7. An apparatus comprising: means for computing at least one uplink transmit power level required toward each of a master node and a secondaiy node; means for determining a total amount of data in a buffer requiring transmission; means for comparing the total amount of data to a preselected data splitting threshold; means for sending the total amount of data to the one of the master node and the secondary node having a smaller required uplink transmit power level, when the total amount of data does not exceed the preselected data splitting threshold; and means for preparing a buffer status report and for providing the buffer status report for a logical channel to a network including the master node and the secondaiy node, the buffer status report including the total amount of data and a split of the total amount of data into two portions based on the at least one uplink transmit power level required toward the master node and the at least one uplink transmit power level required toward the secondaiy node, when the total amount of data exceeds the preselected data splitting threshold.

8. The apparatus as claimed in claim 7, wherein the split of the total amount of data into two portions is in inverse proportion to the ratio between the required uplink transmit power levels.

9. The apparatus as claimed in claim 7, further comprising: means for sending the larger of the two portions of the total amount of data to the one of the master node and the secondary node having a lower required uplink transmit power level.

10. A computer program product comprising a non-transitory computer-readable storage medium bearing computer program code embodied therein for use with a computer, the computer program code comprising code for performing: computing at least one uplink transmit power level required toward each of a master node and a secondary node; determining a total amount of data in a buffer requiring transmission; comparing the total amount of data to a preselected data splitting threshold; when the total amount of data does not exceed the preselected data splitting threshold, sending the total amount of data to the one of the master node and the secondary node having a smaller required uplink transmit power level; and when the total amount of data exceeds the preselected data splitting threshold, preparing a buffer status report and providing the buffer status report for a logical channel to a network including the master node and the secondary node, the buffer status report including the total amount of data and a split of the total amount of data into two portions based on the at least one uplink transmit power level required toward the master node and the at least one uplink transmit power level required toward the secondary node.

11. The computer program product as claimed in claim 10, wherein the split of the total amount of data into two portions is in inverse proportion to the ratio between the required uplink transmit power levels.

12. The computer program product as claimed in claim 10, wherein the computer program code further comprises code for performing: sending the larger of the two portions of the total amount of data to the one of the master node and the secondary node having a lower required uplink transmit power level.

13. A method comprising : receiving a buffer status report including the total amount of data and an indication of a split of the total amount of data into two portions to be accommodated by each of a first network node and a second network node; allocating the required uplink radio resources to the user equipment for uplink transmission of a first portion of data to the first network node; and when allocating all of the required uplink resources for uplink transmission of the first portion of data to the first network node is not possible, identifying a third portion of data, the third portion of data being a remaining part of the first portion of data, and communicating with the second network node to request the second network node to allocate the required uplink radio resources to the user equipment for uplink transmission of the second portion of data plus the third portion of data.

14. The method as claimed in claim 13, further comprising: allocating the required uplink resources to accommodate the larger of the two portions of data when the at least one uplink transmit power level of the user equipment towards the first network node is lower than that of the second network node.

15. An apparatus comprising: at least one processor; and at least one memory including computer program code, the at least one memory and the computer program code being configured, with the at least one processor, to cause the apparatus to perform the following: receive a buffer status report including the total amount of data and an indication of a split of the total amount of data into two portions to be accommodated by each of a first network node and a second network node; allocate the required uplink radio resources to the user equipment for uplink transmission of a first portion of data to the first network node; and when allocating all of the required uplink resources for uplink transmission of the first portion of data to the first network node is not possible, identify a third portion of data, the third portion of data being a remaining part of the first portion of data, and communicate with the second network node to request the second network node to allocate the required uplink radio resources to the user equipment for uplink transmission of the second portion of data plus the third portion of data.

16. The apparatus as claimed in claim 15, wherein the at least one memoiy and the computer program code are further configured, with the at least one processor, to cause the apparatus to perform the following: allocate the required uplink resources to accommodate the larger of the two portions of data when the at least one uplink transmit power level of the user equipment towards the first network node is lower than that of the second network node.

17. An apparatus comprising: means for receiving a buffer status report including the total amount of data and an indication of a split of the total amount of data into two portions to be accommodated by each of a first network node and a second network node; means for allocating the required uplink radio resources to the user equipment for uplink transmission of a first portion of data to the first network node; and means for identifying a third portion of data, the third portion of data being a remaining part of the first portion of data, and for communicating with the second network node to request the second network node to allocate the required uplink radio resources to the user equipment for uplink transmission of the second portion of data plus the third portion of data, when allocating all of the required uplink resources for uplink transmission of the first portion of data to the first network node is not possible.

18. The apparatus as claimed in claim 17, further comprising: means for allocating the required uplink resources to accommodate the larger of the two portions of data when the at least one uplink transmit power level of the user equipment towards the first network node is lower than that of the second network node.

19. A computer program product comprising a non-transitory computer-readable storage medium bearing computer program code embodied therein for use with a computer, the computer program code comprising code for performing: receiving a buffer status report including the total amount of data and an indication of a split of the total amount of data into two portions to be accommodated by each of a first network node and a second network node; allocating the required uplink radio resources to the user equipment for uplink transmission of a first portion of data to the first network node; and when allocating all of the required uplink resources for uplink transmission of the first portion of data to the first network node is not possible, identifying a third portion of data, the third portion of data being a remaining part of the first portion of data, and communicating with the second network node to request the second network node to allocate the required uplink radio resources to the user equipment for uplink transmission of the second portion of data plus the third portion of data.

20. The computer program product as claimed in claim 19, wherein the computer program code further comprises code for performing: allocating the required uplink resources to accommodate the larger of the two portions of data when the at least one uplink transmit power level of the user equipment towards the first network node is lower than that of the second network node.