Improving energy efficiency of radio resource management decisions in o-ran networks

Abstract

A system and method for improving energy efficiency of Radio Resource Management (RRM) in Open Radio Access Network (O-RAN) wireless networks that specifies Low Energy Scheduling Solutions (LESS) at a Distributed Unit (DU) to improve energy saving in Radio Units (RUs) by scheduling data transmission to allow transition to an energy savings mode during non-transmission while maintaining acceptable performance requirements for connected UE and associated DRBs.

Description

Improving Energy Efficiency of Radio Resource Management Decisions in O-RAN NetworksBACKGROUND1. Field of the Disclosure

[0001] The present disclosure relates to Open Radio Access Network (O-RAN) wireless networks and more particularly to improving energy efficiency of Radio Resource Management (RRM) in O-RAN Networks.2. Description of Related Art

[0002] An overview of Next Generation Radio Access Network (NG-RAN) architecture and 5G New Radio (NR) stacks is presented below. 5G NR (New Radio) user and control plane functions with monolithic gNodeB (gNB) are shown in FIGS. 1A, 1B and 2. For the user plane (shown in FIG. 1A, which is in accordance with 3GPP TS 38.300), Physical (PHY), Medium Access Control (MAC), Radio Link Control (RLC), Packet Data Convergence Protocol (PDCP) and Service Data Adaptation Protocol (SDAP) are sublayers that originate in the UE 101 and are terminated in the gNB 102 on the network side.

[0003] As shown in FIG. 1B, which is a block diagram illustrating the user plane protocols stacks for a Protocol Data Unit (PDU) session, in accordance with 3GPP TS 23.501, PDU layer 9010 corresponds to the PDU carried between the UE 101 and the data network (DN) 9011 over the PDU session. As shown in FIG. 1B, UE 101 is connected to the 5G Access Network (AN) 902, which AN 902 is in turn connected via the N3 interface to the Intermediate UPF (I-UPF) 903a portion of the UPF 903, which I-UPF 903a is in turn connected via the N9 interface to the PDU session anchor 903b portion of the UPF 903, and which PDU session anchor 903b is0017303WOU / 4688 connected to the DN 9011. The PDU session can correspond to IPv4, IPv6, or both types of IP packets, when the PDU session is of type IPv4, IPv6 or IPv4v6, respectively. GTP-U shown in FIG. 1B supports tunnelling user plane data over N3 and N9 interfaces and provides encapsulation of end user PDUs for N3 and N9 interfaces.

[0004] For the control plane (shown in FIG. 2, which is in accordance with 3GPP TS 38.300), Radio Resource Control (RRC), PDCP, RLC, MAC and PHY sublayers originate in the UE 101 and are terminated in the gNB 102 on the network side, and Non-Access Stratum (NAS) originate in the UE 101 and is terminated in the Access Mobility Function (AMF) 103 on the network side.

[0005] NG-Radio Access Network (NG-RAN) architecture from 3GPP TS 38.401 is shown in FIGS. 3 and 4. As shown in FIG. 3, the NG-RAN 301 comprises a set of gNBs 302 connected to the 5GC 303 through the NG interface. Each gNB comprises gNB-CU 304 and one or more gNB-DU 305 (FIG. 3). As shown in FIG. 4, which illustrates separation of Control Unit-Control Plane (CU-CP) and Control Unit-User Plane (CU-UP), El is the interface between gNB-CU-CP 304a and gNB-CU-UP 304b; Fl-C is the interface between gNB-CU-CP 304a and gNB-DU 305; and Fl-U is the interface between gNB-CU-UP 304b and gNB-DU 305. As shown in FIG. 4, gNB 302 may comprise a gNB-CU-CP 304a, multiple gNB-CU-UPs (or gNB-CU-UP instances) 304b and multiple gNB-DUs (or gNB-DU instances) 305. One gNB-DU 305 is connected to only one gNB-CU-CP 304a, and one gNB-CU-UP 304b is connected to only one gNB-CU-CP 304a.

[0006] Note that Fl -Application Protocol (Fl-AP) running on Fl-C is specified in 3GPP TS38.473 version 18.1.0, and NR User Plane (NR-U) running on Fl-U is specified in 3GPPTS38.425 version 18.0.0.

[0007] An overview of Layer 2 (L2) of 5G NR is provided in connection with FIGS. 5-7. L2 of 5GNR is split into the following sublayers (in accordance with 3GPP TS 38.300):

[0008] 1) MAC 501 in FIGS. 5-7: Logical Channels (LCs) are Service Access Points (SAPs) between the MAC and RLC layers. This layer runs a MAC scheduler to schedule radio resources across different LCs (and their associated radio bearers). For the downlink direction, the MAC layer processes and sends RLC PDUs received on LCs to the PHY as Transport Blocks (TBs). For the uplink direction, it receives TBs from the PHY, processes these and sends to the RLC layer using the LCs.

[0009] 2) RLC 502 in FIGS. 5-7: The RLC sublayer presents RLC channels to the PDCP sublayer. The RLC sublayer supports three transmission modes: RLC-Transparent Mode (RLC-TM), RLC-Unacknowledged Mode (RLC-UM) and RLC-Acknowledgement Mode (RLC-AM). RLC configuration is per logical channel. It hosts Automatic Repeat Request (ARQ) protocol for RLC-AM mode.

[0010] 3) PDCP 503 in FIGS. 5-7: The PDCP sublayer presents Radio Bearers (RBs) to the SDAP sublayer. There are two types of Radio Bearers: Data Radio Bearers (DRBs) for data and Signaling Radio Bearers (SRBs) for control plane.

[0011] 4) SDAP 504 in FIGS. 5-7: The SDAP maps (Quality of Service) QoS flows within a PDU session to a specific Data Radio Bearer.

[0012] Referring now to FIGS. 5 -7, FIG. 5 is a block diagram illustrating DL L2 structure, FIG. 6 is a block diagram illustrating UL L2 structure, and FIG. 7 is a block diagram illustratingL2 data flow example where “H” denotes headers or sub-headers. All of FIGS. 5 - 7 are provided in accordance with 3GPP TS 38.300.

[0013] Open Radio Access Network (O-RAN) is based on disaggregated components, which are connected through open and standardized interfaces based on 3 GPP NG-RAN. An overview of O-RAN with disaggregated Centralized Unit (CU), Distributed Unit (DU), and Radio Unit (RU), near-real-time Radio Intelligent Controller (RIC) and non-real-time RIC is illustrated in FIG. 8.

[0014] As shown in FIG. 8, the CU (shown split as O-CU-CP 801a and O-CU-UP 801b) and the DU (shown as O-DU 802) are connected using the Fl interface (with Fl-C for control plane and Fl-U for user plane traffic) over a mid-haul (MH) path. One DU can host multiple cells (e.g., one DU could host 24 cells) and each cell may support many users. In one example, one cell may support 800 Radio Resource Control (RRC)-connected users and out of these 800, there may be subset of 250 Active users (i.e., users that have data to send at a given point of time).

[0015] A cell site can comprise multiple sectors, and each sector can support multiple cells. As an example, one site could comprise three sectors and each sector could support eight cells (with each cell being on a different frequency band in each sector). One CU-Control Plane (CU-CP) could support multiple DUs and thus multiple cells. For example, a CU-CP could support 500 cells and around 100,000 different User Equipment (UE). Each UE could support multiple Data Radio Bearers (DRBs) and there could be multiple instances of CU-User Plane (CU-UP) to serve these DRBs. For example, each UE could support 4 DRBs, and 400,000 DRBs (corresponding to 100,000 UE) may be served by five CU-UP instances (and one CU-CP instance).

[0016] The DU could be in a private data center, or it could be located at a cell-site. The CU could also be in a private data center or even hosted on a public cloud system. The DU and CU,which are typically located at different physical locations, could be located many kilometers from each other. The CU communicates with a 5G core system, which could also be hosted in the same public cloud system (or could be hosted by a different cloud provider). A RU (shown as O-RU 803 in FIG. 8) is located at a cell-site and communicates with the DU via a front-haul (FH) interface.

[0017] The E2 nodes (CU and DU) are connected to the near-real-time RIC 132 using the E2 interface. The E2 interface is used to send data (e.g., user and / or cell KPMs) from the RAN, and deploy control actions and policies to the RAN at near-real-time RIC 132. The applications or services at the near-real-time RIC 132 that deploys the control actions and policies to the RAN are called xApps. During the E2 setup procedures, the E2 node advertises the metrics it can expose, and an xApp in the near-RT RIC can send a subscription message specifying key performance metrics which are of interest. The near-real-time RIC 132 is connected to the non-real-time RIC 133, which is shown as part of Service Management and Orchestration (SMO) Framework 805 in FIG. 8 using the Al interface. The applications that are hosted at non-RT-RIC are called rApps. Also shown in FIG. 8 are Open evolved Node B (O-eNB) 806, which is shown as being connected to the near-real-time RIC 132 and the SMO Framework 805 and O-Cloud 804, which is shown as being connected to the SMO Framework 805.

[0018] As in FIG. 8B, E2 node (which is DU or CU) and Near-RT-RIC establish E2 session using E2 SETUP REQUEST and E2 SETUP RESPONSE. Near-RT-RIC can subscribe to certain parameters from the E2 node on behalf the xApp running at Near-RT-RIC using the RIC SUBSCRIPTION REQUEST. The E2 node acknowledges this message by sending RIC SUBSCRIPTION RESPONSE to the Near-RT-RIC. As part of this, xApp running at the Near-RT-RIC also provides the event triggers to the E2 node (e.g., it could ask the E2 node to0017303WOU / 4688 REPORT subscribed parameters periodically to the xApp or to REPORT these subscribed parameters based on certain events to the xApp). The E2 node communicates subscribed parameters to the Near-RT-RIC and the xApp using RIC INDICATION as shown in FIG. 8B. After analysing received parameters from the E2 nodes and based on network operator policies, the Near-RT-RIC can send RIC CONTROL REQUEST to take an action at the E2 node (e.g. influence mobility decision). The E2 node acknowledges this message by sending RIC CONTROL ACKNOWLEDGE to Near-RT-RIC while E2 node functions as instructed by the Near-RT-RIC.

[0019] PDU sessions, DRBs, and Quality of Service (QoS) flows will now be discussed. In 5G networks, PDU connectivity service is a service that provides exchange of PDUs between a UE and a Data Network (DN) identified by a Data Network Name (DNN). The PDU Connectivity service is supported via PDU sessions that are established upon request from the UE. The DNN defines the interface to a specific external data network. One or more QoS flows can be supported in a PDU session. All the packets belonging to a specific QoS flow have the same 5G QoS Identifier (5QI). A PDU session comprises the following: Data Radio Bearers that are between UE and CU in RAN; and an NG-U GTP tunnel that is between CU and User Plane Function (UPF) in the core network. FIG. 9 illustrates an example PDU session (in accordance with 3GPP TS 23.501) comprising multiple DRBs, where each DRB may comprise multiple QoS flows. In FIG. 9, three components are shown for the PDU session 901: UE 101; AN 902; and UPF 903, which includes Packet Detection Rules (PDRs) 9031.

[0020] 3GPP 5G network architecture is illustrated in FIGS. 10 and 11. FIG. 10 is provided in the context of multiple PDU sessions involving multiple DRBs and QoS Flow Identifiers (QFIs), which PDU sessions are implemented involving UE 101, gNB 102, UPF 903, and DNNs 9011aand 901 lb. FIG. 11 is provided in the context of Radio Resource Management (RRM) for connecting UE 101 to the network via RU 306 with a MAC Scheduler 1001. The following should be noted:

[0021] 1) The transport connection between the base station (i.e., CU-UP 304b of FIG. 11) and the UPF 903 uses a single GTP-U tunnel per PDU session, as shown in FIGS. 10 and 11. The PDU session is identified using GTP-U Tunnel Endpoint Identifier (TEID).

[0022] 2) The transport connection between the DU 305 and the CU-UP 304b of FIG. 11 uses a single GTP-U tunnel per DRB (see also FIG. 10 and FIG. 11). The DU is provided with an UL GTP-U TEID and the CU is provided with the corresponding DL GTP-U TEID to allow for data communication for that DRB between DU and CU-UP.

[0023] 3) SDAP:a) The SDAP (Service Adaptation Protocol) 504 Layer receives downlink data from the UPF 903 across the NG-U interface (see FIG. 11).b) The SDAP 504 maps one or more QoS Flow(s) onto a specific DRB.c) The SDAP header is present between the UE 101 and the CU (when reflective QoS is enabled), and includes a field to identify the QoS flow within a specific PDU session.

[0024] 4) GTP-U protocol includes a field to identify the QoS flow and is present between CU and UPF 903 (in the core network).

[0025] 5) One (logical) DU (or RLC) queue exists per DRB (or per logical channel) for RLC PDUs that are to be transmitted for the first time, as shown in FIG. 11. Separate logical queues may exist in DU for packets that are to be retransmitted to UE.

[0026] In this section, standardized 5QI to QoS characteristics mapping is discussed. As per 3GPP TS 23.501, the one-to-one mapping of standardized 5QI values to 5G QoS characteristics is specified in Table 1. The first column represents the 5QI value. The second column lists the different resource types, i.e., as one of Non-GBR, GBR, Delay-critical GBR. The third column (“Default Priority Level”) represents the priority level Priority5QI, for which lower the value the higher the priority of the corresponding QoS flow. The fourth column represents the Packet Delay Budget (PDB), which defines an upper bound for the time that a packet may be delayed between the UE and the N6 termination point at the UPF. The fifth column represents the Packet Error Rate (PER). The sixth column represents the maximimum data burst volume for delay-critical GBR types. The seventh column represents averaging window for GBR, delay critical GBR types. Note that only a subset of 5QI values are shown in Table 1.5QI Value Resource Default Packet Packet Default Default Example Type Priority Delay Error Rate Maximum Averaging Services Level Budget Data Burst Window(Note 3) Volume(Note 2)1 GBR Note 1 20 100 mS 10-2N / A 2000 mS Conversational (Note 11, Voice Note 13)2 GBR Note 1 40 150 mS 10-3N / A 2000 mS Conversational (Note 11, Video (live Note 13) streaming) 3 GBR Note 1 30 50 mS (Note 10-3N / A 2000 mS Real Time 11, Note 13) Gaming (V2X messages (see TS 23287

[0121] ) Electricity distribution - medium voltage, Process automation monitoring 4 GBR Note 1 50 300 mS 10-6N / A 2000 mS Non- (Note 11, Conversational Note 13) Video(BufferedStreaming) 5 (Note 9, GBR Note 1 7 75 mS (Note 10-2N / A 2000 mS Mission Note 12) 7, Note 8) Critical user plane Push To Talk voice (e.g, MCPTT) (Note 12) GBR Note 1 20 100 mS 10-2N / A 2000 mS Non-Mission- (Note 10, Critical user Note 13) plane Push- To-Talk voice (Note 12) GBR Note 1 15 100 mS 10-3N / A 2000 mS Mission (Note 10, Critical Video Note 13) user plane (Note 14) GBR Note 171 GBR Note 1 56 150 mS 10‘° N / A 2000 mS “Live” Uplink (Note 11, Streaming Note 13, (e g, TS Note 15) 26.238

[0076] ) 72 GBR Note 1 56 300 mS IO'4N / A 2000 mS “Live” Uplink (Note 11, Streaming Note 13, (e.g, TS Note 15) 26.238

[0076] ) 73 GBR Note 1 56 300 mS 10'8N / A 2000 mS “Live” Uplink (Note 11, Streaming Note 13, (e.g, TS Note 15) 26.238

[0076] ) 74 GBR Note 1 56 500 mS 10'8N / A 2000 mS “Live” Uplink (Note 11, Streaming Note 13, (e.g, TS Note 15) 26.238

[0076] ) 76 GBR Note 1 56 500 mS IO'4N / A 2000 mS “Live” Uplink (Note 11, Streaming Note 13, (e.g, TS Note 15) 26.238

[0076] ) 5 Non-GBR 10 lOO mS 10-6N / A N / A IMS Note 1 (Note 10, Signalling Note 13)6 Non-GBR 60 300 mS 10’6N / A N / A Video Note 1 (Note 10, (Buffered Note 13) Streaming)TCP-based (e.g, www, e- mail, chat, ftp, p2p file sharing, progressive video, etc.)7 Non-GBR 70 100 mS 10-3N / A N / A Voice, Video Note 1 (Note 10, (Live Note 13) Streaming) Interactive GamingTable 1

[0027] For example, as shown in Table 1, 5QI value 1 is of resource type GBR with the default priority value of 20, PDB of 100ms, PER of 0.01, and averaging widnow of 2000 ms.Conversational voice falls under this catogery. Similarly, as shown in Table 1, 5QI value 7 is of resource type Non-GBR with the default priority value of 70, PDB of 100ms and PER of 0.001. Voice, video (live streaming), and interactive gaming fall under this catogery.

[0028] Radio Resource Management (RRM) is now discussed (a block diagram for an example RRM with a MAC Scheduler is shown in FIG. 11). L2 methods (such as MAC scheduler) play a critical role in allocating radio resources to different UEs in a cellular network. For example, the scheduling priority of a logical channel (PLC) could be determined as part of MAC scheduler using one of the following (or some other variant) for a LC sending data in the downlink direction:PLC= W5QI*P5QI+ WGBR*PGBR+WPDB* PPDB +WBO*PBO + WPF*PPF, orPLC = (W5QI*P5QI) *(WPF*PPF) * (WGBR*PGBR)*(WPDB* PPDB), orPLC = (W5QI*P5QI+ WPF*PPF) * maximum (WGBR*PGBR, WPDB* PPDB) + WBO*PBO, orPLC= (W5QI*P5QI+ WPF*PPF) + maximum (WGBR*PGBR, WPDB* PPDB) + WBO*PBO

[0029] Once one of the above methods is used to compute scheduling priority of a logical channel corresponding to a UE in a cell, the same method is used for all other UEs and these scheduling priorities are used to determine the resources to be allocated to each LC in each cell.

[0030] RANs account for a large amount of energy use for an operator in an end-to-end cellular network. A major part of this energy is used within the RU with Power Amplifiers (PAs) consuming a major portion.

[0031] With many UEs in a cell, each UE could experience different radio conditions and may support different types of traffic for its DRBs, and some of these may be associated with different slices with varying performance requirements. In addition, there can be many cells in a cluster of cells, and this may cause interference for UEs in the overlapping areas of cells with identical frequency bands.

[0032] A base station needs to meet various performance requirements of these UEs and associated DRBs (such as QoS requirements per DRB, minimum throughput requirements per GBR DRB, and so on), while at the same time the base station needs to achieve maximum possible energy savings. Satisfying such diverse performance requirements is a complex problem.

[0033] Accordingly, there is a need for RAN that overcome, alleviate, and / or mitigate one or more of the aforementioned and other deleterious effects relating to power consumption of prior art RAN systems.SUMMARY

[0034] The present disclosure provides a system and method for lowering energy consumption of RANs.

[0035] It is further desired to provide a system and method that specifies Low Energy Scheduling Solutions (LESS) to improve energy saving in a base station.

[0036] It is still further desired to provide a system and method that allows a base station to provide acceptable performance requirements for connected UE and associated DRBs, while at the same time achieving maximum possible energy reduction.

[0037] In a wireless base station (e.g., 5G gNB or LTE eNB), a Low-Energy Scheduler Solution (LESS) at DU seeks to schedule data transmission to find opportunities to move an RU to a lower power state for multiple time intervals where each such interval could be even a few milliseconds or longer. This has the potential to result in a relatively large level of power saving for the base station.

[0038] In one configuration, energy consumption in a base station is reduced by computing a value for an energy saving metric referred to as p£5that using metrics that utilizes metrics including: p5Q / , pPDB, pB0,and pCL.

[0039] For this application the following terms and definitions shall apply:

[0040] P? QI is the priority metric corresponding to the QoS class (5QI) of the logical channel. Incoming traffic from a DRB is mapped to Logical Channel (LC) at RLC level. PSQI is a function of the default 5QI priority value, PrioritysQi, of a QoS flow that is mapped to the current LC. The lower the value of Priori tys i the higher the priority of the corresponding QoS flow. For example, Voice over New Radio (VoNR) (with 5QI of 1) will have a higher PSQI compared to web browsing (with 5 QI of 9).

[0041] PGBR is the priority metric corresponding to the target bit rate of the corresponding logical channel. The GBR metric PGBR represents the fraction of data that must be delivered to the UE within the time left in the current averaging window Tavwin (as per 5QI table, default is 2000msec.) to meet the UE’s GBR requirement. PGBR is calculated as follows:PGBR = remData! targetDataWhere, targetData is the total data bits to be served in each averaging window Tavgwin in order to meet the GFBR (Guaranteed Flow Bit Rate) of the given QoS flow; remData is the amount of data bits remaining to be served within the time left in the current averaging window; PGBR is reset to 1 (or some other suitable value) at the start of each averaging window TaVg win, and should go down to 0 towards the end of this window if the GBR criterion is met; and PGBR = 0 for non-GBR flows. For GBR DRB m corresponding to UE h, remData at time t is denoted as remData(h, m; t) and targetData at time t is denoted as targetData(h, m; t).

[0042] PPDB is the priority metric corresponding to the packet delay budget at DU for the corresponding logical channel. PPDB = 1 if PDBDU<=QDelayRLc and PPDB = 1 / (PDBDU-QDelayRLc) if PDBDU> QDelayRLc where both PDBDU(Packet Delay Budget at DU) and RUC Queuing delay, QDelayRLc, are measured in terms of (time) slots. For example, each (time) slot could be equal to 1 ms or 0.5 ms.

[0043] ‘ Slot’ and ‘time slot’ are used interchangeably in this document.

[0044] QDelayRLc = (t -TRLC) is the delay of the oldest RLC packet in the QoS flow that has not been scheduled yet, and it is calculated as the difference in time between the SDU insertion in RLC queue to current time where t:= current time instant, TRLC:= time instant when oldest SDU was inserted in RLC.

[0045] Packet delay budget at DU is denoted as PDBDU. Waiting time for HoL RLC packet for DRB m corresponding to UE h at time t (i.e. in slot t) is denoted as QDelayRLc(h, m; t).

[0046] PPF is the priority metric corresponding to proportional fair metric of the UE. PPF is the PF Metric, calculated on a per UE basis asaiPPF = -^pTWhere, r: It is the UE’s achievable data rate. DU considers CSI (Channel Status Information) which also includes CQI (Channel Quality Indication), reported by UE to compute this; Ravg= a *Ravg+ (1-a) * b. Specifically, Ravg(t)= a *RaVg(t-1) + (1-a) *b(t), UE’s exponentially weighted moving average throughput, where b(t)>=0 is the number of bits scheduled in the current slot t and parameter ‘a’ is selected such that 0 < a <= 1.

[0047] al and?1 are configurable parameters. For example, if one sets al=l and?1 = 0, the priority metric, PPF, favors UEs in good channel conditions. This helps to improve cell throughput but need not be fair to individual logical channels and some of these UCs may not meet their QoS requirements.

[0048] For some existing systems, al and (31 are in the range of 0 to 1. We allow a to be upper bounded by al max (and lower bounded by zero). As a EC is eventually selected by the overall scheduling priority of a logical channel (PLC) which has multiple other factors (and not only the PPF metric), we allow al_max to be even higher than one (for example, al_max = 1.2) to help design and enforce various type of policies (and associated service level agreements at per-cell, per-DU and per-logical channel level). Similarly, (31, is upper bounded by (31_max, and lower bounded by zero.

[0049] For UE h, achievable data rate in slot t is denoted as r(h; t), which is influnced by CSI reported by UE h for slot t denoted as CSI(h; t). Also, UE’ s weighted average throughput for UEh at the beginning of slot t or at the end of the slot (t-1) is denoted as RaVg(h; t-1).

[0050] BO is the (normalized) buffer occupancy in the RLC queue (e g., in the RLC queue at DU for traffic in the downlink direction for a DRB). PBO is the normalized value of buffer occupancy across all DRBs, which could be proportional to the value of BO.

[0051] RLC queue (normalized) BO for DRB m corresponding to UE h at time t is denoted as RLCBO(h, m; t).

[0052] In addition, the following weights are defined:WSQI is the weight of PSQI;WGBR is the weight of PGBR;WPDB is the weight of PPDB;WBois the weight of PBO;WPF is the weight of PPF.Each of the above weights could be set to a value between 0 and 1 though other suitable set of values can be chosen.

[0053] For a LC sending data in the uplink direction, scheduling priority of that logical channel, PLC can be computed using one of the following methods (or some other variant):PLC= W5QI*P5QI+ WGBR*PGBR+WBSR*PBSR + WPF*PPF, orPLC= (W5QI*P5QI) *(WPF*PPF) * (WGBR*PGBR)*(WBSR* PBSR),

[0054] For UL, UE reports Buffer Status Report (BSR) to DU based on the data, which is waiting in the UL queues at the UE and this BSR can be used to estimate the (UL) BO. DifferentLogical Channel Groups (LCGs) can be used depending on the type of traffic. For example, one LCG can be used for GBR traffic and another GBR can be used for non-GBR traffic. A separate LCG can be used for signalling traffic.

[0055] For each GBR DRB m (corresponding to UE h) that is sending data in the uplink direction, remData(h,m;t) and targetData(h,m;t) at time t are computed by monitoring data received in the UL direction from the UE at the DU.

[0056] The PF metric for a UE can be computed using the MCS and the corresponding TB size for the UL direction for that UE. The weighted average throughput (Ravg) for the UL traffic from each UE can be computed at the DU by monitoring UL traffic from that UE.

[0057] Carbon credits are the permits or the certificates that allow an organization to emit certain amount of Carbon Dioxide or other greenhouse gases. Typically, one carbon credit represents one metric ton of Carbon Dioxide or its equivalent in other greenhouse gases. A government or regulatory body sets the limit for overall emissions from a certain sector. Another entity may provide a quote for carbon credits to different industries in that sector. If an organization uses less than the quote of carbon credits allocated to it, then it can sell corresponding extra carbon credits to someone who is exceeding the limits.

[0058] For this application the following terms and definitions shall apply:

[0059] The term “data” as used herein means any indicia, signals, marks, symbols, domains, symbol sets, representations, and any other physical form or forms representing information, whether permanent or temporary, whether visible, audible, acoustic, electric, magnetic, electromagnetic or otherwise manifested. The term “data” as used to represent predeterminedinformation in one physical form shall be deemed to encompass any and all representations of the same predetermined information in a different physical form or forms.

[0060] The term “network” as used herein includes both networks and internetworks of all kinds, including the Internet, and is not limited to any particular type of network or inter-network.

[0061] The terms “first” and “second” are used to distinguish one element, set, data, object or thing from another, and are not used to designate relative position or arrangement in time.

[0062] The terms “coupled”, “coupled to”, “coupled with”, “connected”, “connected to”, and “connected with” as used herein each mean a relationship between or among two or more devices, apparatus, files, programs, applications, media, components, networks, systems, subsystems, and / or means, constituting any one or more of (a) a connection, whether direct or through one or more other devices, apparatus, files, programs, applications, media, components, networks, systems, subsystems, or means, (b) a communications relationship, whether direct or through one or more other devices, apparatus, files, programs, applications, media, components, networks, systems, subsystems, or means, and / or (c) a functional relationship in which the operation of any one or more devices, apparatus, files, programs, applications, media, components, networks, systems, subsystems, or means depends, in whole or in part, on the operation of any one or more others thereof.

[0063] As used herein, the term “p5Q / ” is a QoS priority metric that is computed using the 5QI priority value of each DRB in 5G networks. For 4G networks, QCI is used instead of 5QI for a given DRB.

[0064] As used herein, the term “pB0” is computed using the Buffer Occupancy (BO)information of a given DRB (e g., in the RLC queue at the DU for DL).

[0065] As used herein, the term “pBBB” is computed using the delay budget criteria for every DRB.

[0066] As used herein, the term “pCL” is computed using cell load (such as the overall PRB utilization or number of active users) in the associated cell.

[0067] In one configuration, a method for minimizing energy consumption in a base station of a Radio Access Network where a set of Data Radio Bearers (DRBs) or Logical Channels (LCs) that include a set of DRBs that have been selected for scheduling is provided, the method comprising the steps of: computing a value of an energy saving metric pBSusing metrics selected from the group consisting of p5QI, pPDB, PBO- PCL and combinations thereof.

[0068] In another configuration, a method for minimizing energy consumption in a Radio Unit (RU) of a Radio Access Network where a set of Data Radio Bearers (DRBs) or Logical Channels (LCs) that include a set of DRBs that have been selected for scheduling using a Low-Energy Scheduler Solution (LESS) module executing on a Distributed Unit (DU) is provided, the method comprising the step of computing a value of an energy saving metric pES- using metrics selected from the group consisting of Quality of Service Priority metric (PSQJ ), Delay Budget Metric (pBBB), Buffer Capacity Metric (pB0), Cell Load Metric (pCL), and combinations thereof. The method further comprises the step of transitioning the RU to an energy savings mode during a time interval based on the computed value of the energy saving metric pES.

[0069] The above-described and other features and advantages of the present disclosure will be appreciated and understood by those skilled in the art from the following detailed description,0017303WOU / 4688 drawings, and appended claims.DESCRIPTION OF THE DRAWINGS

[0070] FIG. 1A is an overview of NG-RAN architecture showing user and control plane functions with gNB according to the prior art.

[0071] FIG. IB is a block diagram of NG-RAN architecture showing user and control plane functions with gNB according to FIG. 1A according to the prior art.

[0072] FIG. 2 is an overview of NG-RAN architecture showing user and control plane functions with gNB and AMF according to FIG. 1A according to the prior art.

[0073] FIG. 3 is a block diagram of NG-RAN architecture with a set of gNBs coupled to the 5GC through an NG interface according to FIG. 1A according to the prior art.

[0074] FIG. 4 is a block diagram of NG-RAN architecture with a set of gNBs coupled to the 5GC through an NG interface with separate CU-CP and CU-UP according to FIG. 3 according to the prior art.

[0075] FIG. 5 is a block diagram of 5G NR illustrating DL L2 structure with various sublayers according to FIG. 1A according to the prior art.

[0076] FIG. 6 is a block diagram of 5G NR illustrating UL L2 structure with various sublayers according to FIG. 1A according to the prior art.

[0077] FIG. 7 is a block diagram of 5G NR illustrating an L2 data flow example according to FIG. 1A according to the prior art.

[0078] FIG. 8A is a block diagram of 0-RAN with the various components connected via the mid-haul path according to FIG. 1A according to the prior art.

[0079] FIG. 8B is a data flow diagram between the E2 node and the Near-RT-RIC according to FIG. 8A according to the prior art.

[0080] FIG. 9 is a block diagram of an example PDU session comprising multiple DRBs that each comprise multiple QoS flows according to FIG. IB according to the prior art.

[0081] FIG. 10 illustrates 3GPP 5G network architecture within the context of multiple PDU sessions with multiple DRBs and QoS flow identifiers according to FIG. IB.

[0082] FIG. 11 illustrates 3GPP 5G network architecture within the context of RRM for connecting UE to the network via and RU with a MAC scheduler according to FIG. IB.

[0083] FIG. 12 is a table illustrating a histogram of a probability density function of pESwhere x-axis is the value of pES- and y axis represents corresponding discrete probabilities.DETAILED DESCRIPTION

[0084] METHOD I

[0085] Whether a Radio Unit (and its associated Power Amplifier) for a cell (or a component carrier) can transition to an energy saving (or sleep) state is influenced by an energy saving metric denoted as pES.

[0086] A MAC scheduler for a cell at the DU selects a set of maximum users that can be scheduled in a slot for this cell in each base station system. The Method I considers the set ofDRBs (or LCs) that include the set of DRBs that have been selected for scheduling and computes a value of this energy saving metric, pESusing the following four metrices, p5QI, pPDB, PBO andPCL-

[0087] For example, there could be nl active DRBs (or LCs) in that cell, and MAC scheduler at the DU can pick up n2 (out of these nl) DRBs to serve in each time slot. In this case, Method I computes the energy saving metric, pES, considering these n2 +r (or n2 * r) DRBs (or max number of active DRBs whichever is lower) where n2 DRBs have been selected by the scheduler for scheduling in that time slot and r is configurable parameter. In addition to per-DRB (or per-LC) factors, this method also considers cell load.

[0088] QoS Priority Metric Psqf. For a DRB that is carrying data for 5QI x, p5QIis computed as a function of Priority5Qi(x). Here, Priority SQI(X) denotes the priority level for 5Q1 x. In general, Priority5Qi(x), is represented as PrioritysQi here. Priority metric p5Q7is computed as> cp5QI“ Priority5QI’Here, ‘c’ is chosen to be less than or equal to the maximum value of Priority5(? / . Note that, p5QIE (0,1]. In the method specified here, there are higher chances for RU to go into energy saving mode with lower values of p5QI.

[0089] Buffer Capacity Metric, pB0: is an LC level metric and is computed every slot. When scheduler has picked the LCs to be served, the fraction of the buffer being used by that LC (in DU) is calculated every slot as follows:Buffer_size_occupied_by_LCBOT otal_Buf fer_size_allocated_to_that_particular_LC0017303WOU / 4688pBO∈ [0,1]. In the method specified here, there are higher chances for RU to move to energy saving mode with lower values of pBOfor several LCs.

[0090] Delay Budget Metric, PPDB It is also an LC (or DRB) level metric.

[0091] Based on the link information of a user, the TB (transport block) size can be calculated. With the information of subcarrier spacing used and the above-calculated TB size, the maximum achievable rate on that link (Rachievabie) for a given user can be determined. A fraction of this is used for a given DRB (for the case when this UE may be supporting multiple DRBs).

[0092] Information of Head-of-Line (HoL) packet size is denoted by H ol_packet_size. HoL or the oldest packet is in the RLC queue for the corresponding DRB (or LC).

[0093] Based on a maximum achievable rate calculated, the feasible rate possible for that link iscomputed using the following expression: Rf= Rachievable / K where K is a function (denoted as f)of various parameters such as number of active DRBs associated with that UE (along with their QoS class such as 5QI in 5G networks or QCI in 4G networks), cell load, CSI of this UE, and the like.

[0094] max_time_avail_in_queue (MTAIQ) is defined as the maximum time that the HoL packet can stay in the RLC queue for a DRB at DU (before missing its DL delay requirements). This is defined as follows:HOL_packet_size MTAIQ = PDB - - - MHdelay — BHdelay — time_in_queue

[0095] MTAIQ for the HoL packet in the RLC queue for LC (or DRB) k is denoted as MTAIQ(k; HoL). In the description of the method here, MTAIQ refers to MTAIQ of the HoL0017303WOU / 4688packet in the RLC queue for a given DRB.

[0096] Here, PDB is the delay budget between core network (CN) to UE for a given DRB (or LC) of a given QoS Class (i.e. 5QI for 5G networks or QCI for 4G networks), MHdelay denotes mid haul delay between CU and DU for a DRB of a given QoS Class, and BHdelay denotes backhaul delay between core network (CN) and CU-UP for a DRB of a given QoS Class and time in queue denotes how much time HoL packet was in the RLC queue before it was scheduled by the L2 scheduler for over-the-air transmission. BHdelay is measured at CU and communicated to DU via the Fl interface for a LC of a given QoS class. MHdelay is directly measured at the DU.

[0097] The delay metric pPDBfor a DRB is defined as:( 1, MTAIQ < yρPDB= { γ / MTAIQ, MTAIQ ≥ γ{MTAIQ’

[0098] Here, y, is a configurable parameter. The value of y could depend on QoS class (e.g. 5QI for 5G, or QCI for 4G) and other factors. Alternatively, it could be dynamically computed. In that case, it can depend on QoS class for this DRB, traffic mix in the cell corresponding to different 5QIs, cell load and other factors.

[0099] pPDB∈ (0,1] and there are higher chances for RU to move to energy saving mode with lower value of pPDB(for several LCs).

[0100] Cell load Metric, pCLThis metric depends on the cell load, and it is used to decide whether (or not) the RU should transition into an energy saving mode for that cell. The value of pCLdepends on various factors, such as, PRB utilization of that cell, the number ofactive users in that cell, and so on. One or more thresholds can be set for the cell load metric, pCL, based on the policies used by the network operator. An example policy is shown below where value of pCLis chosen (e.g., configured) based on PRB utilization in that cell.• When PRB utilization < PRB^t=> pCL= p“L• When 20% < PRB utilization <PRB^ta=> pCL= p^L• When 50% < PRB utilization < PRB^t=> pCL= pCcL• When 80% < PRB utilization => pCL= 1For example, PRB utilization PRB“tilcould be 20%, PRB^tilcould be 50% and PRB^tiicould be 80%. Also, pLcould be 0.1, p^Lcould be 0.2 and pLcould be 0.5

[0101] As another example, only one threshold can be used for the cell load. If the cell load is less than 85% (e.g., in terms of PRB utilization in that cell), energy savings operation can be triggered as described using the method here.

[0102] This method uses the metric p£5to decide whether RU can switch to energy saving mode or not. In this energy saving method, weighting is given to cell load metric, pCL, allowing better energy saving when the cell load is comparatively less.• In every slot, the L2 scheduler (running in the DU) selects a maximum n number of LCs to be served in that slot. This can be done using one of the scheduling policies described earlier or using any other scheduling policy. This method now calculates the LC level metric p' for each LC that is selected for scheduling by the scheduler using below equation:P'= X5Q / P5Q / +XPDBPPDB +XBOPBOWhere, p' is the weighted mean of p5QI, pPDBand pB0, and we have p' ∈ [0,1]; x5QI, xPDBand xB0are the weights assigned to the respective metrices. These weights are between 0 and 1 and could be configured based on operator policies.• LC level metric, p', for LC i is denoted as p[. This method computes variable p, which is the weighted mean of the LC metrics p' for all the LCs scheduled by the scheduler and this uses QoS priority metric, p5QI, as the weight for each LC metric.r?=i(p5QI)ipiΣni=1(p5QI)iWhere, i is the ithLC and n is the total number of LCs which have been selected for scheduling by the scheduler, (p5(3Z). is the QoS priority metric for LC i.• This method next computes pESas:PES = wrip + wCLpCLWhere, and wCLare the weights associated to the p and pCLrespectively. pESshould be less than a threshold value to transition to an energy saving mode, and when it exceeds that threshold value, the RU operates in regular mode. Depending on operator policies, we can also haveX5Q1XPDBXBO-.

[0103] As another policy, p can be computed as an average of p', accounting for each LC i.η = (1 / n) Σi=1npiWhere, r| is the weighted mean of p' and we have η ∈ [0,1]; pESis the weighted mean of r| and pCL, and we have pES6 [0,1].

[0104] Energy saving mode for a base station (BS), is given as:Energysaving_mode, if pES<BSjnode —Regularmode(i.e. if pES≥

[0105] Here, T is a threshold set by the operator to trigger the energy saving mode. A suitable value can be chosen in the range (0, 1). There is a tradeoff between QoS experienced by different users in the cell and energy saving targets of the cell, and this influences choice of a suitable value of T.

[0106] In this method four metrices for every time slot are computed, out of which three are LC level metrices and one is cell level metric. First, the weighted mean of LC level metrices is taken for each LC and then the term η is calculated by combining all LCs scheduled by the scheduler. Next, it is combined with the cell load by taking a weighted mean at the cell level to generate the final metric pES, which is compared with a threshold given by the operator, and this is used to decide whether to serve users (or LCs) in a given time slot. If it is decided not to serve any user in that slot, this can be used by the RU (and other components of gNB) to transition to energy saving mode.

[0107] Thus, every time slot (or set of time slots) by calculating metric pES, RU will be in working in either regular mode or energy saving mode and will reduce energy consumption when there is less load at the cell level and when QoS requirements are not violated for different users present in the cell.0017303WOU / 4688

[0108] It will be notes that if any type of mandatory control information is expected in a slot (such as MIB or SIBs in 4G or 5G networks), the metric pESneed not be computed in that slot.METHOD II

[0109] As discussed earlier, pES- is a performance measure defining the energy saving metric, and T is the tunable threshold, which controls the amount of energy saving. This energy saving metric, pES, is computed as in Method I.

[0110] Method II enhances Method I and helps to find a good value of threshold, T, which is needed for a given energy saving target.

[0111] Suppose after implementing Method I, energy savings of y% is obtained for a given scenario for a given T. With this, the RU could transition to the energy saving mode for f(y)% of the time where f(y) is computed using function f of y. This function f can be differentfor RUs from different vendors. With Method I, this means Prob(pES< T) =. HereProb(pES< T) represents the probability of (pES< T).

[0112] For some RUs, it could be that f(y) = y. For some other RUs, this relationship may not necessarily be linear.

[0113] In some scenarios, a network operator may want to increase this energy saving from y% to (y + 8)%. A network operator can choose a suitable value of 8 using the target saving in terms of carbon credits targets or based on previous experiences.

[0114] This method helps to find a correct value of T' to achieve energy saving of (y + s)%.

[0115] For finding the probability density function (PDF) of pES, many samples of pES- are collected and a histogram version of the PDF of pESis generated. The PDF of pESis denoted as / p(p) and looks like the example shown in FIG. 12 where x-axis is the value of pESand y axis represents corresponding discrete probabilities.

[0116] Considering f(y) = y, and after having the histogram version of the PDF of pES, the values of the histogram version of PDF / p(p) are added by varying the values of p from 0 toT, so that the sum value is almost equal toand thus giving the optimal value of T so that theenergy saving of y% is obtained.

[0117] To increase the energy saving from y% to (y + 8)%, it is necessary to change the value of T to T', for the new optimal value for energy saving, which can be computed by adding the values of histogram version of PDF fp(p) by varying the values of p from 0 to T', so that thesum value is almost is equal tothus giving us the new optimal value of T to T' so that theenergy saving is (y + 8)%.

[0118] Method II facilitate determining a good value of T' to increase energy saving of a cell from (y)% to (y + 8)%.

[0119] The following Abbreviations are applicable:5GC: 5G Core Network5GNR: 5G New Radio5QI: 5G QoS IdentifierACK: AcknowledgementAl: Artificial IntelligenceAI / ML (or AIML): Artificial Intelligence and Machine LearningAID: Assistance Information DataAM: Acknowledged ModeAMBR: Aggregate Maximum Bit RateAPN: Access Point NameARP: Allocation and Retention PriorityBLER: Block Error RateBO: Buffer OccupancyBS: Base StationBSR: Buffer Status ReportCMS: Centralized (or Configuration) Management SystemCNN: Convolution Neural NetworkCP: Control PlaneCSI: Channel State InformationCU: Centralized UnitCU-CP: Centralized Unit - Control PlaneCU-UP: Centralized Unit - User PlaneD2-U: D2-User Plane (for D2 interface)D2-C: D2-Control Plane (for D2 interface)D2AP: D2 Application Protocol (running over the D2-C interface)DBS: Desired Buffer SizeDL: DownlinkDDDS: DL Data Delivery StatusDDR: Desired Data RateDNN: Data Network NameDNN: Deep Neural NetworkDQN: Deep Q NetworkDRB: Data Radio BearerDU: Distributed UniteNB: evolved NodeB (or eNodeB)eNodeB: Evolved NodeB (or eNB)EPC: Evolved Packet CoreEN-DC: E-UTRAN New Radio Dual Connectivity (E-UTRA-NR Dual Connectivity)Fl-U: Fl -User PlaneFl-C: Fl -Control PlaneF1AP: Fl Application ProtocolGBR: Guaranteed Bit RategNB: gNodeBGTP-U: GPRS Tunnelling Protocol - User PlaneIP: Internet ProtocolLI: Layer 1L2: Layer 2L3: Layer 3L4S: Low Latency, Low Loss and Scalable Throughput LC: Logical ChannelLESS: Low Energy Scheduler SolutionLSTM: Long Short-Term MemoryLTE: Long Term EvolutionMAC: Medium Access ControlMDP: Markov Decision ProcessMCG: Master Cell GroupMeNB: Master eNB (or Master eNodeB)MeNB DU: DU of MeNBMeNB. CU-CP: CU-CP of MeNBMeNB. CU -UP: CU-UP of MeNBMIB: Master Information BlockML: Machine LearningMN: Master NodeMR-DC: Multi -RAT Dual ConnectivityMSS: Maximum Segment SizeMU-MIMO: Multi-User Multiple-Input Multiple-Output NACK: Negative AcknowledgementNAS: Non-Access StratumNG-RAN: Next Generation Radio Access NetworkNR-NR DC: New Radio (5G) - New Radio (5G) Dual Connectivity (Architecture) NR-U: New Radio - User PlaneNSA: Non-Standalone ArchitectureNSI: Network Slice InstanceNSSI: Network Slice Subnet InstanceNWDAF: Network Data Analytics FunctionO-RAN: Open Radio Access NetworkOAM: Operations, Administration MaintenancePDB: Packet Delay BudgetPDCP: Packet Data Convergence ProtocolPDU: Protocol Data UnitPER: Packet Error RatePF: Proportional FairPHY: Physical LayerPRB: Physical Resource BlockQCI: QoS Class IdentifierQFI: QoS Flow IdentifierQoS: Quality of ServiceRAN: Radio Access NetworkRAT: Radio Access TechnologyRB: Resource BlockRDI: Reflective QoS Flow to DRB IndicationRL: Reinforcement LearningRLC: Radio Link ControlRLC-AM: RLC Acknowledged ModeRLC-UM: RLC Unacknowledged ModeRNN: Recurrent Neural NetworksRQI: Radio Quality IndicationRRC: Radio Resource ControlRRM: Radio Resource ManagementRTP: Real-Time Transport ProtocolRTCP: Real-Time Transport Control ProtocolRU: Radio UnitSCG: Secondary Cell GroupSCTP: Stream Control Transmission ProtocolSD: Slice DifferentiatorSDAP: Service Data Adaptation ProtocolSDU: Service Data UnitSession-AMBR: Per-Session Aggregate Maximum Bit Rate SgNB: Secondary gNB (or Secondary gNodeB) SgNB. CU: CU of SgNBSgNB. CU-CP: CU-CP of SgNBSgNB. CU-UP: CU-UP of SgNBSgNB. DU: DU of SgNBSIB: System Information BlockSLA: Service Level AgreementSN: Secondary NodeS-NSSAI: Single Network Slice Selection Assistance SST: Slice / Service TypeSU-MIMO: Single User Multiple-Input Multiple-Output TB: Transport BlockTCP: Transmission Control ProtocolTEID: Tunnel Endpoint IdentifierUE: User EquipmentUE-AMBR: Per-UE Aggregate Maximum Bit RateUP: User PlaneUL: UplinkUM: Unacknowledged ModeUPF: User Plane FunctionX2-U: X2-User PlaneX2-C: X2-Control PlaneX2AP: X2 Application Protocol

[0120] While the present disclosure has been described with reference to one or more exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the disclosure without departing from the scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as the best mode contemplated, but that the disclosure will include all embodiments falling within the scope of the appended claims.

Claims

CLAIMSWhat is claimed is:

1. A method for minimizing energy consumption in a Radio Unit (RU) of a Radio Access Network where a set of Data Radio Bearers (DRBs) or Logical Channels (LCs) that include a set of DRBs that have been selected for scheduling using a Low-Energy Scheduler Solution (LESS) module executing on a Distributed Unit (DU), the method comprising the steps of:computing a value of an energy saving metric pESusing metrics selected from the group consisting of Quality of Service Priority metric (ρ5QI), Delay Budget Metric (ρPDB), Buffer Capacity Metric (ρBO), Cell Load Metric (ρCL), and combinations thereof; andtransitioning the RU to an energy savings mode during a time interval based on the computed value of the energy saving metric pES.

2. The method of claim 1, wherein data transmission for the DU is scheduled during times other than the time interval when the RU is in the energy saving mode.

3. The method of claim 1, wherein for a DRB that is carrying data for 5QI x, p5QIis computed as a function of Priority SQI(X) that denotes a priority level for 5QI x and is computed as:> cp5<3 / “ Priority5(3;’where, ‘c’ is chosen to be less than or equal to the maximum value of Priority5(3 / ,the chances of RU transitioning to the energy saving mode increasing when the value of ρ5QIis below a threshold value for several LCs.

4. The method of claim 1, wherein the delay metric pPDBfor a DRB is defined as:f1’ MTAIQ < yρPDB= { γ / MTAIQ, MTAIQ ≥ γ{MTAIQ’where, y, is a configurable parameter that depends on QoS class or is dynamically computed and depends on QoS class for this DRB, traffic mix in the cell corresponding to different 5QIs, and cell load, and MTAIQ, is max_time_avail_in_queue defined as the maximum time that the Head-of-Line (HoL) packet can stay in a Radio Link Controller (RLC) queue for a DRB at the DU, andthe chances of RU transitioning to the energy saving mode increasing when the value of pPDBis below a threshold value for several LCs.

5. The method of claim 1, further comprising the steps of:selecting an LC to be served with a scheduler where a fraction of buffer used by the selected LC is calculated every slot, the pBOcalculated as follows:Buffer_size_occupied_by_LCρBO= Buffer_size_occupied_by_LC / Total_Buffer_size_allocated_to_that_particular_LCthe chances of RU transitioning to the energy saving mode increasing when the value of ρBOis below a threshold value for several LCs.

6. The method of claim 1, wherein pCLdepends on PRB utilization of that cell, and the number of active users in that cell, and uses the metric ρCLto determine whether the RU can switch to the energy saving mode, andweighting is according to pCLfacilitating increased energy saving when the cell load iscomparatively lower.

7. The method of claim 6, wherein ρESis computed as:ρES= wηη + wCLρCLwhere, wηand wCLare the weights associated to the η and ρCLrespectively, and η is computed as an average of ρi, accounting for each LC i,η = (1 / n)Σρiwhere, η is the mean of ρi, andthe RU transitioning to the energy saving mode when ρESis less than a threshold value denoted as T.

8. The method of claim 6, where η is computed as weighted average of ρi, accounting for each LC i, with weight used is proportional to ρ5QIfor each LCΣi=1(ρ5QI)iρiS”=1(P5(2 / )Zthe RU transitioning to the energy saving mode when ρESis less than a threshold value.

9. The method of claim 6, wherein ρCLdepends on PRB utilization of that cell, and the number of active users in that cell, where a threshold for pCLis based on PRB utilization in a cell, the threshold set as follows:when PRB utilization < PRB“ta=> pCL= pELwhen 20% < PRB utilization <PRBbutil=> ρCL= ρbCLwhen 50% < PRB utilization < PRB^ltil=> pCL— pCcLwhen 80% < PRB utilization => pCL= 1where,PRB^tibPRBytil, p“L, p^Land pCcLare configured based on operator policies.

10. The method of claim 1, wherein the step of transitioning the RU to an energy savings mode comprises transitioning the RU to the energy savings mode for multiple time intervals based on the energy saving metric ρES.

11. The method of claim 1, wherein the Radio Access Network is selected from the group consisting of: Fifth Generation gNodeB ( 5G gNB), Long Term Evolution evolved Node B (LTE eNB) or combinations thereof.

12. The method of Claim 1 where a good value of threshold T' (for ρES) is found to increase energy saving from y% to (y + δ)% using histogram version of the probability density function of ρES.

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