Reducing radio unit power consumption based on centralized unit control

Abstract

A base station for reducing power consumption in a radio unit. The base station includes at least one processor configured to, during light traffic conditions, schedule all user traffic for a frame into a minimum number of slots that include synchronization signal block (SSB) traffic. The at least one processor is also configured to trigger at least one power reduction step for the radio unit in response to receiving information from at least one centralized unit indicating activity level for at least one slot or symbol.

Description

REDUCING RADIO UNIT POWER CONSUMPTION BASED ON CENTRALIZED UNIT CONTROL CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to US Provisional Patent Application No. 63 / 770,896, filed March 12, 2025, titled “REDUCING RADIO UNIT POWER CONSUMPTION BASED ON CENTRALIZED UNIT CONTROL”, which is incorporated herein by reference in its entirety.BACKGROUND

[0002] Operating cost is a major factor that wireless network operators consider in order to maintain cost effective operations. Accordingly, it may be beneficial to reduce radio unit power consumption in base stations.SUMMARY

[0003] A base station for reducing power consumption in a radio unit. The base station includes at least one processor configured to, during light traffic conditions, schedule all user traffic for a frame into a minimum number of slots that include synchronization signal block (SSB) traffic. The processor(s) are also configured to trigger at least one power reduction step for the radio unit in response to receiving information from at least one centralized unit indicating activity level for at least one slot or symbol.

[0004] A method for reducing power consumption in a radio unit in a base station. The method includes, during light traffic conditions, scheduling all user traffic for a frame into a minimum number of slots that include synchronization signal block (SSB) traffic. The method includes triggering at least one power reduction step for the radio unit in response to receiving information from at least one centralized unit indicating activity level for at least one slot or symbol.DRAWINGS

[0005] Understanding that the drawings depict only exemplary configurations and are not therefore to be considered limiting in scope, the exemplary configurations will be described1 Docket 7069 WO W1 / 376.2178WO01with additional specificity and detail using the accompanying drawings, in which:

[0006] Figure 1 A is a block diagram illustrating one exemplary embodiment of a system in which the techniques described here for reducing radio unit power consumption can be used;

[0007] Figure IB is a block diagram illustrating another exemplary embodiment of a system in which the techniques described here for reducing radio unit power consumption can be used;

[0008] Figure 2 is a block diagram illustrating an example 5G NR frame structure in which each subframe (e.g., 1 ms) includes two slots (e.g., 0.5 ms), and each slot includes 14 OFDM symbols;

[0009] Figure 3 is a block diagram illustrating a digital signal processing block (DSP), an RF front end unit, and antenna in a radio unit;

[0010] Figure 4 is a block diagram illustrating a scheduler used in the present systems and methods;

[0011] Figure 5 is a block diagram illustrating radio unit functions that may be disabled using the second technique;

[0012] Figure 6 is a block diagram illustrating an example resource block mapping that consolidates user traffic 185A-D into the minimum number of slots that already contain SSBs;

[0013] Figure 7 is a block diagram illustrating an example DSP with radio power control circuitry that selectively disables circuitry in the RF front end unit;

[0014] Figure 8 is a block diagram illustrating another example DSP with radio power control circuitry that selectively disables circuitry in the RF front end unit;

[0015] Figure 9 is a transistor characteristic curve diagram illustrating variable drain bias conditions in a power transistor operating in class AB corresponding to the variable drain voltage regulation in Figure 7 and / or Figure 8; and

[0016] Figure 10 is a waveform diagram illustrating a time-domain representation of how the drain bias voltage of the transistor would be varied relative to the average power of the transmitted symbol in the configuration of Figure 7 and / or Figure 8;

[0017] Figure 11 is a flow diagram illustrating a method for reducing power consumption in a radio unit;2 Docket 7069 WO W1 / 376.2178WO01

[0018] Figure 12A is a circuit diagram illustrating an example metal-semiconductor fieldeffect transistor (MESFET) that may be used to implement a transistor with the present systems and methods; and

[0019] Figure 12B is a circuit diagram illustrating another example MESFET with variable voltage regulators.

[0020] In accordance with common practice, the various described features are not drawn to scale but are drawn to emphasize specific features relevant to the exemplary configurations.DETAILED DESCRIPTION

[0021] A significant factor in the total operating expenses of distributed wireless communication networks is the cost of the electrical power that must be provided to the radio units or remote access points. This applies to wireless macro networks as well as in-building small cell networks (such as a cloud radio access network, “C-RAN”) or distributed antenna systems. A significant percentage of the power consumed by these radio units or remote access points is in the digital signal processing (DSP) and radio frequency (RF) power amplifier (PA) circuits. Often, the power consumed by the DSP blocks is a function of the total amount of bandwidth process through these blocks which is determined by the number of carriers, bandwidth of each carrier, and the number of uplink and downlink MIMO paths. In contrast, the power consumed by the RF power amplifier circuits is more a function of the signal amplitude, power amplifier power rating, power amplifier efficiency, and number of downlink MIMO paths.

[0022] Previous techniques used in the radio configuration (e.g., of a 5G base station) incrementally reduce power consumption by shutting down radio resources in the radio unit in response to reduced throughput demand as sensed at the radio unit. This autonomous sensing in the radio unit may introduce latency in the signal path, e.g., the radio unit may introduce a symbol of latency while sensing the power for a symbol or slot.

[0023] In contrast to previous techniques, the present systems and methods temporarily disable certain circuit blocks in the radio unit transmitter during empty symbols or slots based on coordination with a centralized unit, such as a distributed unit (e.g., the scheduler function in a DU), to relay explicit information about upcoming slots and / or symbols to allows radio3 Docket 7069 WO W1 / 376.2178WO01circuitry (or portions of it) in the radio unit to turn off during unoccupied slots or symbols. The present systems and methods are especially useful for the Third Generation Partnership Project (3GPP) Fifth Generation New Radio (5G NR) systems but could work with Long Term Evolution (LTE) and other air interfaces. Additionally, when the RU receives an explicit message about inactive symbols and / or slots from the centralized unit, such as a gNB DU, it may be more accurate than autonomously sensing this information in some configurations.

[0024] During reduced or “light” traffic periods (periods during which all resource blocks in symbol(s) are not fully loaded, also referred to as “lightly loaded” symbols or slots), the traffic scheduler function of the gNodeB (gNB) or eNodeB (eNB) baseband section may take active measures to schedule the traffic in a manner that consolidates traffic from lightly loaded slots or symbols into fewer slots or symbols. This allows radio unit resources to be disabled for brief periods with no user traffic. A 5G distributed unit (DU) or a 4G baseband controller may communicate with radio unit through a fronthaul control channel to provide explicit information to the radio unit about the timing of such periods and the various signal parameters, such as amplitude information.

[0025] As described herein, this invention includes multiple techniques for radio unit power reduction that may be implemented under control of the gNB (e.g., DU) or eNB by communication of active symbol or slot signal amplitude information to the RU and by strategic scheduling of resource blocks to minimize the number of active slot or symbols within a frame and maximize the inactive interval length within a frame. Each of the techniques described herein may be implemented individually or in combination to achieve RU power consumption reduction enabled by control of the gNB (e.g., DU) or eNB.

[0026] As used herein, the term “traffic” can refer to downlink data intended sent to a user (e.g., transmitted by a radio unit in a base station using the physical downlink shared channel (PDSCH)) or uplink data sent from the user (e.g., transmitted by a UE using the physical uplink shared channel (PUSCH)). Generally, and without limitation, the term traffic does not refer to overhead / control messages, e.g., transmitted on the physical uplink control channel (PUCCH) or the physical downlink control channel (PDCCH).

[0027] The sequence of techniques or steps described herein could be implemented in any order or all at once as the traffic demand changes, though particular orders of steps may be used as examples herein, i.e., “first technique” is not meant to imply an order relative to a4 Docket 7069 WO W1 / 376.2178WO01“second technique”, etc. Additionally, the techniques or steps described herein could be used in any combination with anywhere from one to all being used in a particular radio unit.

[0028] Example 5G System

[0029] Figure 1A is a block diagram illustrating one exemplary embodiment of a system 101 A in which the techniques described here for reducing radio unit power consumption can be used. The system 101A includes one or more base stations 100. The term base station 100 herein refers to any electronic device configured to receive and transmit RF signals to provide wireless service to user equipment (UEs) 110. Typically, base stations 100 are in a fixed location, however other configurations are possible.

[0030] In the exemplary embodiment shown in Figure 1A, one of the base stations 100A is implemented using a centralized or cloud RAN (C-RAN) architecture that employs, for each cell (or sector) 102 served by the base station 100 A, the following logical nodes: at least one control unit (CU) 103, at least one distributed unit (DU) 105, and multiple radio units (RUs) 108. Each RU 108 is remotely located from each CU 103 and DU 105 serving it. Also, in this exemplary embodiment, at least one of the RUs 108 is remotely located from at least one other RU 108 serving that cell 102.

[0031] Without limitation, types of base stations include a cloud radio access network (C-RAN) 100A, a small cell 100B, a macro base station 100C, etc. Small cells 100B are generally lower-power, shorter-range, and can serve fewer max concurrent users than macro base stations 100C. For example, small cell(s) 100B may be used to fill in coverage gaps in macro base station 100C coverage, e.g., indoors, in urban environments, etc. In some cases, a C-RAN 100A may be considered a type of small cell 100B. It should be noted that the present systems and methods may be implemented using any number of C-RANs 100 A, other types of small cells 100B, and / or macro base stations 100C.

[0032] The C-RAN 100 A can be implemented in accordance with one or more public standards and specifications. In some configurations, the C-RAN 100A is implemented using the logical RAN nodes, functional splits, and fronthaul interfaces defined by the O-RAN Alliance. In such an O-RAN example, each CU 103, DU 105, and RU 108 can be implemented as an O-RAN central unit (CU), O-RAN distributed unit (DU), and O-RAN radio unit (RU), respectively, in accordance with the O-RAN specifications. That is, each CU 103 comprises a logical node hosting Packet Data Convergence Protocol (PDCP), Radio Resource Control (RRC), Service Data Adaptation Protocol (SDAP), and other control5 Docket 7069 WO W1 / 376.2178WO01functions. In some configurations, each DU 105 comprises a logical node hosting Radio Link Control (RLC), and Media Access Control (MAC) layers as well as the upper or higher portion of the Physical (PHY) layer (where the PHY layer is split between the DU 105 and RU 108). Each RU 108 comprises a logical node hosting the portion of the PHY layer not implemented in the DU 105 (that is, the lower portion of the PHY layer) as well as implementing the basic RF and antenna functions.

[0033] Although the CU 103, DU 105, and RUs 108 are described as separate logical entities, one or more of them can be implemented together using shared physical hardware and / or software. For example, in the exemplary embodiment shown in Figure 1A, for each cell 102, the CU 103 and DU 105 serving that cell 102 could be physically implemented together using shared hardware and / or software, whereas each RU 108 would be physically implemented using separate hardware and / or software.

[0034] Also, in the exemplary embodiment described here in connection with Figure 1A, the C-RAN 100A is implemented as a Fifth Generation New Radio (5G NR) RAN that supports a 5G NR wireless interface in accordance with the 5G NR specifications and protocols promulgated by the Third Generation Partnership Project (3GPP). Thus, in some configurations, the C-RAN 100A can also be referred to as a “Next Generation Node B” 100, “gNodeB” 100, or“gNB” 100.

[0035] Each RU 108 includes or is coupled to one or more antennas 122 via which downlink RF signals are radiated to various items of user equipment (UE) and via which uplink RF signals transmitted by UEs 110 are received.

[0036] The CU 103 and / or DU(s) 105 is / are coupled to a core network 112 of the associated wireless network operator over an appropriate back-haul network 116 (such as the Internet). Also, each DU 105 is communicatively coupled to the RUs 108 served by it using a fronthaul network 118. Each of the DU(s) 105 and RUs 108 include one or more network interfaces (not shown) to enable the DU(s) 105 and RUs 108 to communicate over the fronthaul network 118.

[0037] In one implementation, the fronthaul 118 that communicatively couples the DU(s) 105 to the RUs 108 is implemented using a switched ETHERNET network 120. In such an implementation, each DU 105 and RU 108 includes one or more ETHERNET interfaces for communicating over the switched ETHERNET network 120 used for the fronthaul 118.6 Docket 7069 WO W1 / 376.2178WO01However, it is to be understood that the fronthaul 118 between each DU 105 and the RUs 108 served by it can be implemented in other ways.

[0038] Each CU 103, DU 105, and RU 108, (and the functionality described as being included therein), as well as any other device in the system 101 A more generally, and any of the specific features described here as being implemented by any of the foregoing, can be implemented in hardware, software, or combinations of hardware and software, and the various implementations (whether hardware, software, or combinations of hardware and software) can also be referred to generally as “circuitry” or a “circuit” or “circuits” configured to implement at least some of the associated functionality. When implemented in software, such software can be implemented in software or firmware executing on one or more suitable programmable processors or configuring a programmable device (for example, processors or devices included in or used to implement special-purpose hardware, general-purpose hardware, and / or a virtual platform). Such hardware or software (or portions thereof) can be implemented in other ways (for example, in an application specific integrated circuit (ASIC), etc.). Also, the RF functionality can be implemented using one or more RF integrated circuits (RFICs) and / or discrete components. Each CU 103, DU 105, RU 108, and the system 101 A more generally, can be implemented in other ways.

[0039] As noted above, in the exemplary embodiment described here in connection with Figure 1A, the C-RAN 100A is implemented as a 5G NR RAN that supports a 5G NR wireless interface to wirelessly communicate with the UEs 110.

[0040] More specifically, in the exemplary embodiment described here in connection with Figure 1A, the 5G NR wireless interface supports the use of beamforming for wirelessly communicating with the UEs 110 in both the downlink and uplink directions using the millimeter wave (mmWave) radio frequency (RF) range defined for 5G NR (Frequency Range 2 or “FR2”), e.g., ranging from 24 GHz to 40 or 100 GHz. 5G NR RAN systems typically make use of fine beams and beamforming, especially when FR2 is used. To perform such beamforming, each RU 108 comprises an array of multiple, spatially separated antennas 122. When FR2 is used, the spacing of the antennas 122 in the array is on the order of several millimeters (as opposed to several centimeters as is the case when FR1 is used) and can be implemented in a convenient fashion.

[0041] Each fine beam concentrates energy in a single narrow direction, thus providing better signal quality for a UE 110 that is within that fine beam. In the downlink direction (that7 Docket 7069 WO W1 / 376.2178WO01is, when the gNB 100 transmits to the UE 110), the directionality of the array is controlled by adjusting the phase and relative amplitude of the signal transmitted from each antenna 122 to create a pattern of constructive and destructive interference in the wavefront. In the uplink direction (that is, when the gNB 100 receives transmissions from the UE 110), the directionality of the array is likewise controlled by adjusting the phase and relative amplitude of the signal received via each antenna 122 to create a pattern of constructive and destructive interference in the resulting combined signal (which results from combining the signals received via all of the antennas 122 in the array). That is, for both downlink and uplink, each fine beam has an associated direction.

[0042] Beamforming can be done in an analog manner (for example, by applying the phase and relative amplitude weights in the RF front-end circuitry in each RU 108), in a digital manner (for example, by applying the phase and relative amplitude weights to the frequencydomain data generated for each antenna 122 for that UE 110 as a part of the lower PHY layer processing performed in each RU 108), or a combination of analog and digital beamforming (also called “hybrid”).

[0043] Although examples may be described as being implemented using FR2, it is to be understood that other frequency ranges can also theoretically be used (for example, the sub 6 Gigahertz (GHz) frequency range defined for 5G NR (Frequency Range 1 or “FR1”)).

[0044] A management system 114 may be communicatively coupled to the CU 103, for example, via the back-haul network 116. The management system 114 may send and receive management communications to and from the CU 103, which in turn forwards relevant management communications to and from the RUs 108. Additionally, the management system 114 may assist in managing and / or configuring the base stations 100. The management system 114 may be communicatively coupled to the CU(s) 103, DU(s) 105, and RUs 108, for example, via the back-haul network 116 and / or the fronthaul network 118. A hierarchical architecture can be used for management-plane (“M-plane”) communications. When a hierarchical architecture is used, the management system 114 can send and receive management communications to and from the baseband controller 104, which in turn forwards relevant M-plane communications to and from the RUs 108 as needed. A direct architecture can also be used for M-plane communications. When a direct architecture is used, the management system 114 can communicate directly with the RUs 108 (without having the M-plane communications forwarded by the CU 103 or DU 105). A hybrid8 Docket 7069 WO W1 / 376.2178WO01architecture can also be used in which some M-plane communications are communicated using a hierarchical architecture and some M-plane communications are communicated using a direct architecture. Proprietary protocols and interfaces can be used for such M-plane communications. Also, protocols and interfaces that are specified by standards such as O-RAN can be used for such M-plane communications.

[0045] Example 4G System

[0046] Figure IB is a block diagram illustrating another exemplary embodiment of a system 10 IB in which the techniques described here for reducing radio unit power consumption can be used. Figure IB includes a C-RAN 100D implementing a 3GPP Fourth Generation (4G) air interface, whereas the C-RAN 100A in Figure 1A implements a 5G air interface. However, it should be noted that a C-RAN 100, or a system 101 more generally, may implement 4G and 5G air interfaces.

[0047] The C-RAN 100D in Figure IB includes one or more baseband units (called baseband controller(s) 104) that interact with multiple radio points (RPs) 106. Each baseband controller 104 is coupled to the RPs over fronthaul communication links or a fronthaul network. Each RP 106 may include or be coupled to at least one antenna via which downlink RF signals are radiated to UEs 110 and via which uplink RF signals transmitted by UEs 110 are received. Furthermore, where an action is described as performed by a C-RAN 100D, it may be performed in the baseband controller 104 and / or at least one RP 106.

[0048] The RPs 106 and UEs 110 connected to (e.g., provided wireless service by) the C-RAN 100D may be located at a site 107. The site 107 may be, for example, a building or campus or other grouping of buildings (used, for example, by one or more businesses, governments, other enterprise entities) or some other public venue (such as a hotel, resort, amusement park, hospital, shopping center, airport, university campus, arena, or an outdoor area such as a ski area, stadium or a densely-populated downtown area). For example, the site 107 may be at least partially indoors, but other alternatives are possible.

[0049] It should be noted that the baseband controller 104 may or may not be located at the site 107 (with the RPs 106). For example, the baseband controller 104 may be physically located remotely from the RPs 106 (and the site 107) in a centralized bank of baseband controllers 104. Additionally, the RPs 106 are preferably physically separated from each other within the site 107, although they are each communicatively coupled to the baseband controller 104.9 Docket 7069 WO W1 / 376.2178WO01

[0050] Each UE 110 may be a computing device with at least one processor that executes instructions stored in memory, e.g., a mobile phone, tablet computer, mobile media device, mobile gaming device, laptop computer, vehicle-based computer, a desktop computer, etc. It should be noted that any number of UEs 110 (e.g., 1-1,000) may be present at the site 107.

[0051] The C-RAN 100D may be coupled to the core network 112 of each wireless network operator over an appropriate back-haul network 116. For example, the Internet (or any other ETHERNET network) may be used for back-haul between each base station 100 and each core network 112. However, it is to be understood that the back-haul network 116 can be implemented in other ways.

[0052] In some configurations, the system 101 may be implemented as a Long Term Evolution (LTE) radio access network providing wireless service using an LTE air interface. In the LTE configuration, the baseband controller 104 and RPs 106 together (C-RAN 100D) may be used to implement an LTE Evolved Node B (also referred to here as an “eNodeB” or “eNB”). An eNodeB may be used to provide UEs 110 with mobile access to the wireless network operator's core network 112 to enable UE 110 to wirelessly communicate data and voice (using, for example, Voice over LTE (VoLTE) technology).

[0053] In an LTE configuration, each core network 112 may be implemented as an Evolved Packet Core (EPC) 112 comprising standard LTE EPC network elements such as, for example, a mobility management entity (MME) and a Serving Gateway (SGW) and, optionally, a Home eNodeB gateway (HeNodeB GW) (not shown) and a Security Gateway (SeGW) (not shown).

[0054] Moreover, in an exemplary LTE configuration, the baseband controller 104 may communicate with the MME and SGW in the EPC core network 112 using the LTE SI interface and communicates with eNodeBs using the LTE X2 interface. For example, the baseband controller 104 can communicate with a macro base station 100C via the LTE X2 interface.

[0055] The baseband controller 104 and RPs 106 can be implemented to use an air interface that supports one or more of frequency-division duplexing (FDD) and / or timedivision duplexing (TDD). Also, the baseband controller 104 and the RPs 106 can be implemented to use an air interface that supports one or more of the multiple-input-multiple-output (MIMO), single-input-single-output (SISO), and / or beam forming schemes. For example, the baseband controller 104 and the RPs 106 can implement one or more of the10 Docket 7069 WO W1 / 376.2178WO01LTE transmission modes. Moreover, the baseband controller 104 and the RPs 106 can be configured to support multiple air interfaces and / or to support multiple wireless operators.

[0056] In some configurations, the fronthaul network 118 that communicatively couples each baseband controller 104 to the one or more RPs 106 is implemented using a standard ETHERNET network. However, it is to be understood that the fronthaul network 118 between the baseband controller 104 and RPs 106 can be implemented in other ways. The fronthaul network 118 may be implemented with one or more switches, routers, and / or other networking devices.

[0057] Data can be fronthauled between the baseband controller 104 and RPs 106 in any suitable way (for example, using fronthaul interfaces and techniques specified in the Common Public Radio Interface (CPRI) and / or Open Base Station Architecture Initiative (OB SAI) family of specifications).

[0058] The Third Generation Partnership Project (3 GPP) has adopted a layered model for the LTE radio access interface. Generally, the baseband controller 104 and / or RPs 106 perform analog radio frequency (RF) functions for the air interface as well as digital Layer- 1 (LI), Layer-2 (L2), and / or Layer-3 (L3), of the 3GPP-defined LTE radio access interface protocol, functions for the air interface. In some configurations, the Layer- 1 processing for the air interface may be split between the baseband controller 104 and the RPs 106, e.g., with L2-L3 functions for the air interface being performed at the baseband controller 104.

[0059] Additionally, it should be noted that the present systems and methods may also be used in other distributed RANs (in addition to a C-RAN 101 A-B), e.g., a distributed antenna system (DAS) connected to a DU 105. For example, a DAS (with spatially-separated radio units and optionally a head unit) may communicate with a DU 105 using an 0-RAN interface (oDAS).

[0060] Where functionality of a 5G CU 103 or 5G DU 105 is described herein, it may also equally apply to a baseband controller 104 in 4G configurations (and / or a head-end unit in a DAS). Similarly, where functionality of a 5G radio unit (RU) 108 is described herein, it may also be implemented an RP 106 in 4G configurations. Additionally, where functionality of a radio unit (RU) 108 is described herein, it may also be implemented in a macro base station 100C or other type of small cell 100B.

[0061] Power Reduction Techniques11 Docket 7069 WO W1 / 376.2178WO01

[0062] As discussed above, operating costs are a significant consideration for 5G network operators. Specifically, 5G network infrastructure may consume significantly more power than similar 4G network infrastructure. In an effort to reduce power consumption in radio units (RUs) 108, one or more power reduction steps may be implemented during hours of light user traffic or no traffic, e.g., very early in the morning or late at night. The power reduction step(s) described herein can be performed in any sequence or combination. Therefore, the modifiers “first,” “second,” “third,” “fourth,” and “fifth” should not be interpreted as requiring an order of the steps relative to each other, e.g., the second step may be performed before or after the first step. Furthermore, one or more of the steps described herein may not be performed at all in some configurations.

[0063] First Technique for Reducing Power Consumption in the Radio Unit

[0064] A first technique to reduce power consumption in the radio unit 108 is to shut down or disable any component(s) of the DSP (e.g., fronthaul packet interface, the low PHY processing, the (digital front end), and / or digital up conversion (DUC) circuitry), and / or the RF front end (e.g., RF upconverter and / or power amplifiers) during slots of the air interface frame in which there is no user traffic.

[0065] Figure 2 is a block diagram illustrating an example 5G NR frame structure in which each subframe 111 (e.g., 1 ms) includes two slots 113 (e.g., 0.5 ms), and each slot 113 includes 14 OFDM symbols. It is understood that other specific configurations of subframes 111, slots 113, and / or symbols 115 may be used with the present systems and methods. In the example configuration, SSBs 117 are included only within the first 4 out of 10 slots 113. Each SSB 117 occupies 20 resource blocks (RBs) over four symbols 115 of each of the four slots 113 of a frame. In some configurations, SSBs 117 may be included within 100 resource blocks (1200 sub-carriers) mapped across the full 10 slots 113 (140 symbols 115) of a frame.

[0066] Each SSB 117 may include four downlink channels that include the Primary Sync Signal (PSS), the Secondary Sync Signal (SSS), the PBCH (Physical Broadcast Channel), and the PBCH DMRS (Demodulation Reference Signal). Since the SSBs 117 are downlink overhead signals that must be transmitted in every downlink frame whether that frame contains user traffic or not, the radio unit transmitter functions cannot be completely disabled during periods of no user traffic, but short periods in which the transmitter functions are disabled may still be implemented. During periods when there is no user traffic, the Synchronization Signal Block (SSB) signals are still transmitted during certain slots of the12 Docket 7069 WO W1 / 376.2178WO015G NR frame in the downlink to enable wireless devices 110 to detect and synchronize with the network.

[0067] Therefore, the first technique for reducing radio unit power consumption is to disable component(s) of the DSP (e.g., fronthaul packet interface, the low PHY processing, the DFE (digital front end), and / or digital up conversion (DUC) circuitry), and / or the RF front end (e.g., RF upconverter and / or power amplifiers) during the slots 113 that do not contain active SSB 117 transmissions (e.g., slots 4-9 in the example of Figure 2) and to enable or activate these circuit block only during slots 113 that contain active SSBs 117 (e.g., slots 0-3 in the example of Figure 2). In this manner, the radio unit transmitter blocks would be enabled or disabled on a slot-by-slot basis. In this technique the scheduler function of the gNB baseband would signal to the radio unit prior to the start of a slot 113 period whether or not it contains any active transmissions, either SSBs 117 or user traffic. This allows the radio unit to accurately time the disabling of the circuit blocks of idle slots and to enable the blocks at the appropriate time for active slots 113.

[0068] Figure 3 is a block diagram illustrating a gNB DU 105 communicating with a digital signal processing block (DSP) 136 in a radio unit 108. The radio unit 108 may communicate with one or more DUs 105 and / or CUs 103 (e.g., via a fronthaul network 118) and one or more wireless devices 110 (e.g., via an air interface). In some configurations, the radio unit 108 includes additional RF front end units 126 (not shown), each with at least one respective antenna 122. For example, if the RU 108 were using 8-column massive MEMO, the RU 108 may have eight RF front end units 126, each with a respective antenna 122. Alternatively, the RU 108 may have less RF front end units 126 than antennas 122 with at least one of the RF front end units 126 having processing signals for more than one antenna 122. In some configurations, each RF front end unit 126 may have an associated one or more digital signal processing block(s) 136, as shown in Figure 3.

[0069] The digital signal processor(s) 136 may send signals intended for UEs 110 to the RF front end unit 126 and receive UE signals from the RF front end unit 126. For example, the digital signal processor 136 may perform processing (including digital signal processing), along with the RF front end unit 126, to convert a baseband signal (e.g., from one or more DUs 105 and / or CUs 103) into an RF signal that is radiated from one or more antennas 122 that are connected to the RF front end unit 126. In some configurations, the digital signal processor 136 may perform processing for an air interface (e.g., a 5G air interface) that is not13 Docket 7069 WO W1 / 376.2178WO01performed in the DU 105 or CU 103, e.g., at least some of the physical layer (LI) processing. Each of the at least one digital signal processor 136 may be an FPGA, ASIC, microprocessor, DSP, etc.

[0070] The RF front end unit 126 and / or digital signal processor(s) 136 may include various components, some of which are shown in Figure 3. However, it is understood that (1) any suitable configuration of the RF front end unit 126 and / or digital signal processor(s) 136 configurations may be used with the present systems and methods; and (2) the DU 105, radio unit 108, DSP 136, and RF front end unit 126 could and likely would have additional components not shown in Figure 3 or described herein. For example, it is possible for the radio unit 108 (e.g., the DSP 136) to perform all or substantially all of the PHY processing in some configurations, e.g., both the high PHY 161 and low PHY 163. The term “high” with respect to PHY (also referred to as “LI” or the “physical layer”) refers to the upper sublayers of the physical layer functions. The term “low” with respect to PHY (also referred to as “LI” or the “physical layer”) processing 163 refers to the lower sublayers of the physical layer functions. Examples of possible high PHY processing 161 and low PHY processing 163 are given below.

[0071] In the example of Figure 3, the DU 105 includes at least one scheduler 171, MAC processing 159 (described in more detail below), high PHY 161 processing, and a fronthaul packet interface 172.

[0072] Without limitation, the high PHY processing 161 (performed at the DU 105) may include any of the following: forward error correction (FEC), layer mapping / demapping, modulation / demodulation, pre-coding, etc.

[0073] In the example of Figure 3, the radio unit 108 includes at least a DSP 136 (with a fronthaul packet interface 172, low PHY processing 163, digital front end 165, digital up conversion (DUC) circuitry 166, and a numerically controlled oscillator (NCO) 164) and an RF front end 126 (with an RF upconverter 151 and a power amplifier 152).

[0074] Without limitation, the low PHY processing 130 (performed at the RU 108) may include, without limitation, any of the following: Fast Fourier Transform (FFT) and inverse Fast Fourier Transform (iFFT) processing, cyclic prefix addition / removal, etc.

[0075] The DSP(s) 136 may include downlink circuitry (e.g., low PHY 163 and digital front end 165) configured to process digital data received from the fronthaul packet interface 172 (via the fronthaul interface 118) before sending digital data to the RF front end unit 12614 Docket 7069 WO W1 / 376.2178WO01for RF processing. Specifically, the DSP 136 (e.g., low PHY 163) may convert frequencydomain baseband samples (encapsulated in IP packets) from the fronthaul packet interface 172 into time-domain samples via inverse FFT (iFFT). A third digital filter may remove any out-of-band remnants introduced by the iFFT. A digital up conversion (DUC) 166 may then digitally upconvert the filtered time-domain samples before sending to the RF front-end unit 126. The DUC 166 may utilize a sinusoidal waveform generated by a numerically controlled oscillator (NCO) 164, which may be the same or different as the NCO 164 utilized by the DDC.

[0076] The DSP 136 may also include uplink circuitry (now shown in Figure 3) configured to process digital data received from a receive chain (not shown in Figure 3) in the RF front end 126. Specifically, the uplink circuitry in the DSP 136 (e.g., digital front end 165) may digitally downconvert samples from an ADC, remove all frequencies (except the PUSCH frequencies) from the downconverted samples perform FFT processing on the remaining PUSCH time-domain samples to produce frequency-domain PUSCH baseband data encapsulated in IP packets. The frequency-domain PUSCH data is transmitted across a fronthaul interface 118 by a fronthaul packet interface 172 for higher level processing. A similar process is performed in parallel for received physical random access channel (PRACH) data. Specifically, all frequencies (except the PRACH frequencies) are removed from the downconverted samples FFT processing is performed on the remaining PRACH time-domain samples to produce frequency-domain PRACH baseband data encapsulated in IP packets. The frequency-domain PRACH data is transmitted across the fronthaul interface 118 by the fronthaul packet interface 172 for higher level processing.

[0077] While not explicitly illustrated in the Figures, the RF front end units 126 described herein may include a receive chain and a transmit chain. The receive chain may include circuitry configured to filter, mix amplify, and / or digitize analog signals received from wireless devices 110 (via one or more antennas 122) and pass them to the digital signal processor(s) 136. Specifically, an RF analog signal may be received wirelessly at the one or more antennas 122 connected to the RF front end unit 126 and fed to a duplexer. The duplexer may be configured to selectively enable a signal from the antenna 122 to pass through the receive chain or a signal from the transmit chain to pass through to the antenna 122, but not both at the same time. In this way, the duplexer may minimize interference between signals in the receive chain and the transmit chain and enable the receive chain and the transmit chain to share the same one or more antennas 122. The duplexer may be15 Docket 7069 WO W1 / 376.2178WO01implemented using one or more switches, filters or other circuitry configured to select between different signal paths. A band-pass filter (BPF) in the receive chain may be configured to filter the received analog signal to prevent out-of-band signals from propagating through the receive chain, i.e., frequency components above and below a particular frequency band may be attenuated or eliminated by the BPF while the components in a desired frequency band remain unattenuated (or minimally attenuated). The output of the BPF may be fed into a low-noise amplifier that may be configured to amplify the output of the BPF. A first mixer may then be configured to mix the output of the LNA with a sinusoidal signal from a local oscillator, e.g., to downconvert the output of the LNA from the RF band of the received signal to an intermediate frequency (IF) band. An analog-to-digital converter (ADC) may be configured to digitize the mixed signal before sending to the digital signal processor(s) 136.

[0078] The transmit chain may include circuitry configured to convert digital signals received from the digital signal processor(s) 136, then mix and amplify the analog signals before they are transmitted to one or more UEs 110 (via the one or more antennas 122). A digital-to-analog converter (DAC) may be configured to convert a digital signal from the digital signal processor(s) 136 to an analog signal, which is then fed into a second mixer. The second mixer may then be configured to mix the output of the DAC with a sinusoidal signal from the local oscillator, e.g., to upconvert the output of the DAC from an intermediate frequency (IF) band to an RF band. The analog RF signal may then be input into a power amplifier (PA) 152 that may be configured to increase the power of the signal before transmitting to one or more wireless devices 110 via the one or more antennas 122.

[0079] Figure 4 is a block diagram illustrating a scheduler 171 used in the present systems and methods. The scheduler 171 is a functional block of the gNB distributed unit (DU) 105 that controls MAC 159 (which receives information from the convergence sublayer 157) and PHY 161 processing to map user and control data into specific resource blocks of each slot 113. Therefore, Figure 4 shows an example DU 105 (with a scheduler 171, MAC 159, and PHY 161 processing) that may be used in the example architecture of Figure 3 in which the scheduler 171 controls the MAC 159 and PHY 161 processing to set the RB mapping within a slot 113 and also signals to a Radio Power Control block 169 of the radio unit to control the enabling and disabling a various radio unit transmitter functions during active or inactive slots 113, respectively.16 Docket 7069 WO W1 / 376.2178WO01

[0080] Without limitation, the Medium Access Control (MAC) processing 159 may include: scheduling processing such as scheduling, mapping of transport channels to logical channels, maintenance of uplink time alignment, hybrid automatic repeat request (HARQ) processing, and / or discontinuous reception (DRX); Radio Link Control (RLC) layer processing such as concatenation, segmentation, reassembly, reordering, and error correction (through ARQ); The DU 105 may also perform Packet Data Convergence protocol (PDCP) layer processing such as service flow classifications, in-sequence delivery of data units, header compression, elimination of duplicates, ciphering and deciphering, and integrity protection and verification; and Radio Resource Control (RRC) layer processing include broadcast of system information, connection control, mobility, and measurement configuration and control. Notably, the scheduler 171 enables during light traffic conditions, scheduling all user traffic for a frame into a minimum number of slots that include synchronization signal block (SSB) traffic.

[0081] In addition to controlling the MAC 159 and high PHY 161 processing in the DU 105, the scheduler 171 may also explicitly send information about empty upcoming slots 113 through the fronthaul interface 118 to radio power control circuitry 169 on the RU 108 (e.g., in the DSP block 136) as shown in Figure 3. This information may explicitly or implicitly identify empty slots 113 and / or explicitly indicate transmit power per slot 113 or symbol 115 (e.g., as calculated by the scheduler 171). Additionally or alternatively, a bitmask may be used in which each bit may correspond to a slot 113 in a particular subframe 111. Additionally or alternatively, the information may identify the last non-empty slot 113 in a particular subframe 111 or the first empty slot 113 in a particular subframe 111.

[0082] This information could be sent from the gNB (e.g., DU 105) to the RU 108 using management-plane (“M-plane”) communications or control-plane (“C-plane”) communications. Additionally or alternatively, the present systems and methods could be used as or in conjunction with a “transmission blanking” mechanism as described in detail at Section 8.4.2.3 “Transmission blanking” in the 0-RAN Working Group 4 (Open Fronthaul Interfaces WG) Control, User and Synchronization Plane Specification version 10.0 from October 2022 (O-RAN.WG4.CUS.0-vl 1.00, available at page 209 of PDF at https: / / specifications.o-ran.org / specifications), which is incorporated herein by reference. In transmission blanking, Section Type 0 messaging is used by the DU 105 to indicate to the RU 108 that certain slot(s) 113 or symbol(s) 115 will not be used (idle periods, guard periods). This Section Type 0 is control-plane (“C-plane”) messaging used for static configuration17 Docket 7069 WO W1 / 376.2178WO01before real-time scheduling starts. Typically, there are no associated U-Plane messages containing IQ data for Section Type 0 communication.

[0083] The radio power control circuitry 169 may then selectively turn off component(s) of the DSP 136 (e.g., fronthaul packet interface 172, the low PHY processing 163, the DFE (digital front end) 165, and / or digital up conversion (DUC) circuitry 166), and / or the RF front end 126 (e.g., RF upconverter 151 and / or power amplifiers 152) during portions of the air interface frame in which there is no user traffic (e.g., slots 4-9 in Figure 2).

[0084] It should be noted that in other solutions for reducing power consumption in the RU 108, the RU may sense unoccupied slots to disable various radio unit transmitter functions. In contrast, here the DU 105 explicitly or implicitly signals across the fronthaul 118 to inform the RU 108 in advance which slots 113 are inactive. So the RU 108 can more efficiently shut down components the RF front end if it receives radio signaling rather than having to sense slots 113. Specifically, the RU 108 (e.g., the radio power control 169 in the DSP 136) is able to look at all the frequency-domain information before FFT processing (e.g., in the DSP 136), and it can know instantly what the amplitude of this symbol 115 is, you know, right at the start of the symbol 115 rather than having to measure the time-domain symbol across the entire symbol period to determine whether the symbol is active or inactive. In other words, the present systems and methods (in which the DU 105 (e.g., scheduler 171) signals information regarding inactive slots) may, in some configurations, effectively remove a symbol duration of latency compared to a solution in which the RU 108 autonomously senses inactive slots 113 or symbols 115. Thus, the present systems and methods would be able to perform power control in RUs 108 in real-time or near real-time (e.g., less than 0.5 or 1 ms of latency).

[0085] Second Technique for Reducing Power Consumption in the Radio Unit

[0086] A second technique for reducing power consumption in the RU 108 is to time the enabling and disabling of the radio unit 108 circuit blocks by the scheduler 171 on a symbol -by-symbol basis (instead of a slot-by-slot basis). This technique would allow further optimization of power consumption by the radio unit 108 such that even within slots 113 that contain SSBs 117, the radio unit 108 resources would be disabled during inactive symbols 115 that contain neither SSBs 117 nor user traffic. This technique may rely on the scheduler block 171 of the DU 105 to signal to the radio unit 108 prior to the start of each symbol 115 period if there will be any active resource blocks within that symbol 115, either SSBs 117 or18 Docket 7069 WO W1 / 376.2178WO01user traffic. This could be detected by the radio unit 108 either by monitoring receipt of symbol resource block data from the DU 105 or by establishing a discrete command from the DU 105 to indicate that the upcoming symbol has active traffic.

[0087] Based on monitoring receipt of symbol resource block data from the DU 105 or by receipt of a discrete command from the DU 105, the radio unit during idle symbols or slots will then disable one or multiple blocks within the transmitter chain to reduce power consumption.

[0088] Figure 5 is a block diagram illustrating radio unit 108 functions that may be disabled using the second technique. Figure 5 illustrates the primary functions of the radio unit digital signal processing (DSP) block 169, which are the low PHY 163, the DFE (digital front end) 165, and the DUCs (digital upconverters) 166. The active / inactive slot and symbol information relayed from the DU 105 scheduler 171 to the radio unit would be captured in the active slot / symbol register 183 prior to the start of the slot 113 or symbol 115. This block 183 would then control (e.g., activate or deactivate) the specific features of the low PHY 163, DFE 165, and / or DUC 166 blocks (e.g., via PHY power control 175, DFE power control, and / or DUC power control 179 blocks) to disable these blocks during inactive periods of the slot 113 or symbol 115 and to quickly activate these blocks during active periods of the same. Typically, for the low PHY 163, the iFFT would be disabled during inactive periods as well as the associated CP (cyclic prefix) blocks. In addition, the DFE (digital front end) section 165 that typically contains digital filters, DUC(s) (digital upconverters) 166, and / or NCOs (numerically controlled oscillators) 164 would also typically be disabled during inactive periods (e.g., via DAC power control 181 and / or NCO power control (not shown) blocks), though other configurations are possible. These blocks (low PHY 163, DFE 165, NCO 164, DCU 166) are typically contained within a digital ASIC (application-specific integrated circuit) or within an FPGA (field programmable gate array) device. These devices are typically Complementary metal-oxide-semiconductor (CMOS) digital logic circuits. A typical characteristic of CMOS circuits is that power consumption is directly related to switching frequency. The higher the switching frequency, the higher the power that is consumed. Therefore, these blocks could be disabled by one or more of several optional methods during inactive slots or symbols. This may include toggling a control signal that holds these blocks in the reset state so that they will not be operating, by switching bias power to these blocks to activate / deactivate them, by gating the data passing through these blocks, and / or alternately by disabling the clocks distributed to these blocks.19 Docket 7069 WO W1 / 376.2178WO01

[0089] The digital signals from the DSP 136 of the radio unit 108 as shown in Figure 5 may be received by the DACs (digital -to-analog converters) 178 in the signal chain to convert the digital samples into an analog signal that is typically either a baseband analog waveform, a digital IF waveform, or a direct RF waveform. The power consumption of these DACs 178, similar to the CMOS digital circuits, is directly related to the sample clock frequency. The higher the sample clock frequency, the more power that the DAC(s) 178 consume. Therefore, the DAC(s) 178 could be disabled during inactive slots or symbols by a control signal that holds these in the reset state so that they will not be operating, by controlling the bias power provided, and / or by disabling the clock signals that are distributed to them to be used as sample clocks. The radio unit 108 would enable and disable the DAC(s) 178 based on either monitoring receipt of symbol resource block data from the DU 105 or by receipt of a discrete command from the DU 105 to indicate that the upcoming symbol or slot has active user traffic or SSBs 117.

[0090] For the radio to respond quickly enough to operate on a per-symbol basis, the RU 108 would need advanced information from the DU 105 to shut off its radio transmitter function(s) on a per-symbol basis (autonomous sensing at the RU 108 may not be fast enough to switch off radio transmitter function(s) within a slot 113 then switch back on in time to transmit the SSB 117 data). So the cell is still active, but radio transmitter function(s) are shut off for certain symbols 115 or slots 113.

[0091] The signal from the DU 105 may be real-time information that controls radio resources. The signal may be management plane or control plane information, e.g., O-RAN transmission blanking using Section Type 0 to indicate to the RU 108 that certain slot(s) 113 or symbol(s) 115 will be empty.

[0092] Third Technique for Reducing Power Consumption in the Radio Unit

[0093] The third technique for reducing power consumption in the RU 108 relates to conditions where there is light traffic (in slots with or without SSBs 117), i.e., all of the resource blocks in a time period (e.g., frame, subframe 111, slot 113, and / or symbol 115) are not fully loaded (also referred to as “lightly loaded”). The total power lightly-loaded symbol(s) (in which all resource blocks are not fully loaded) transmitted from the power amplifier is below it is rated power level. Specifically, the third technique includes (1) the scheduler 171 consolidating all user traffic 185 within a frame into the minimum number of slots 113 that already contain SSBs 117; and optionally (2) scheduling the user traffic into the20 Docket 7069 WO W1 / 376.2178WO01minimum number of symbols 115 within these slots 113 that already contain SSBs 117.

[0094] The third technique may include creating, applying, and / or using a scheduler policy that groups all user traffic 185 within a frame into the minimum number of slots 113 that already contain SSBs 117 and / or all user traffic 185 within a frame into the minimum number of symbols 115 that already contain SSBs 117. A scheduler policy that groups all the user traffic into the same slots or symbols where there are also SSBs allows the transmitter to shut off completely for more symbols compared to if that user traffic were scattered across the whole slot period and you have to keep the entire transmitter active through the whole slot.

[0095] Since the scheduler 171 controls the RB mapping of each upcoming slot 113, it can be programmed to efficiently control the placement of user traffic 185 within the frame and can be provided capability to signal that placement information to the radio unit 108 prior to the start of any slot 113. Thus the first approach in the third technique is to consolidate the user traffic into the slots 113 that already contain SSBs 117 to allow transmitter resources to be shut down during unused slots.

[0096] Figure 6 is a block diagram illustrating an example resource block mapping that consolidates user traffic 185A-D into the minimum number of slots that already contain SSBs 117. In this example, since the SSBs 117 are contained in the first four slots 113 of a 10-slot frame, all user traffic 185A-D could be consolidated into only these four slots thereby allowing the radio unit resources to be disabled during the other six slots of the frame. If the amount of user traffic 185A-D exceeds what can be contained within these first four slots 113, then user traffic 185A-D would be scheduled into additional slots 113, again consolidating into the minimum number of slots 113 to allow the radio unit resources to be disabled for the maximum number of contiguous idle slots 113. Consolidating user traffic 185A-D into the minimum number of contiguous slots 113 maximizes inactive interval length and, therefore, power reduction in the RU 108.

[0097] The second approach in the third technique described here for conditions of reduced or light user traffic 185A-D is to not only schedule the user traffic 185A-D into the minimum number of slots 113 that would already contain SSBs 117, but then to schedule the user traffic 185A-D into the minimum number of symbols 115 within these slots 113. In so doing, radio unit resources could be disabled on a symbol-by-symbol basis even within active slots 113. Therefore, during conditions of reduced or light user traffic 185A-D, by consolidating the user traffic 185A-D into slots 113 and symbols 115 that contain SSBs 117 and to21 Docket 7069 WO W1 / 376.2178WO01consolidate into the minimum number of slots 113 and symbols 115, this allow the radio unit 108 resources to be disabled during idle slots 113 and symbols 115 to minimize power consumption. In these techniques, the radio unit 108 enables and disables circuit blocks either by monitoring receipt of symbol resource block data from the DU 105 or by receipt of a discrete command from the DU 105 to indicate that the upcoming symbol 115 or slot 113 has active user traffic 185A-D or SSBs 117.

[0098] In other solutions, a radio unit 108 could monitor the digital IQ samples from the DU 105 and create an amplitude estimate of that average symbol amplitude and then control the bias on the power amplifier 152 to adjust the bias commensurate with the amount of transmit power that was required. Thus, the power could be reduced for symbols 115 or slots 113 that were lightly loaded. In the present systems and methods, the RU 108 relies on the DU 105 to send slot 113 or amplitude information. If slot 113 information is sent from the DU 105 to the RU 108, the scheduler 171 in the DU 105 would determine the highest power symbol 115 in the slot 113 and send that information to the radio, which would scale the gate voltage and drain bias on the power amplifier so that the power amplifier could reduce power consumption during those lightly loaded slots. For example, a symbol 115 where only half the resource blocks were loaded might be transmitted at half the RF power that it would if it were fully loaded. During empty slots 113 and symbols 115, the radio may still be completely disabled whenever possible. If amplitude information is sent to the RU 108 (on a slot 113 by slot 113 basis or a symbol 115 by symbol 115 basis), the DU 105 calculates the amplitude of each symbol 115 so that during lightly loaded symbols 115 the power amplifier 152 can be biased to a much lower power consuming condition, e.g., only what’s required to transmit that symbol while still meeting the linearity requirements of 3 GPP but at a much lower power.

[0099] Fourth Technique for Reducing Power Consumption in the Radio Unit

[0100] The fourth technique for reducing power consumption in the RU 108 includes disabling specific analog signal chain circuit(s) and / or RF power amplifiers 152 of the transmitters during inactive slots 113 and / or symbols 115. This could be implemented by a discrete or multiple discrete control signals produced by the DSP block 136 or the radio unit 108.

[0101] Figure 7 is a block diagram illustrating an example DSP 136 with radio power control circuitry 169 that selectively disables circuitry in the RF front end unit 126. As1 Docket 7069 WO W1 / 376.2178WO01illustrated in Figure 7, control signals may be used to place the analog circuits and RF power amplifiers (e.g., in the RF front end 126) into low power states during the inactive slot 113 or symbol 115 periods. This can be implemented by enabling and disabling the power regulator circuit that supplies DC power to each of these blocks. Alternately, the control signal can disable and enable the circuits by controlling the gate and / or drain functions of the circuit transistors. In the RF power amplifiers 152, the control signal could alternately be used to control the gate and / or drain of the final power transistor device and driver transistor device by pinching off the transistors during the inactive periods and then returning the device to the normal gate and / or drain bias condition during the active slots or symbols. Again, the radio unit may enable and disable the analog circuits and RF power amplifiers 152 by producing discrete control signals from the DSP block 136 based on either monitoring receipt of symbol resource block data from the DU 105 or by receipt of a discrete command from the DU 105 to indicate that the upcoming symbol 115 or slot 113 has active user traffic 185 or SSBs 117.

[0102] For symbol -by-symbol changes in the amplitude and corresponding bias state, the slot amplitude may be determined by the DU 105 and written to the Slot-Symbol Amplitude Register 183. Alternately for slot-by-slot indexing of the bias conditions, the DU 105 may calculate the root mean square (RMS) amplitude on a slot basis based on the largest amplitude symbol within that slot and to then write this to the radio unit Slot / Symbol Amplitude Register 183 prior to the start of each slot 113. This may allow the radio unit 108 to set the power amplifier drain bias state for the entire slot period based on this maximum symbol amplitude.

[0103] Since making any changes to the bias voltage of the power amplifier 152 transistor during a symbol 115 period may degrade modulation accuracy or EVM (error vector magnitude), the radio unit 108 must have prior knowledge of the upcoming symbol 115 or slot 113 amplitude in order to set the drain bias to the optimum state prior to the start of the symbol 115 or slot 113, respectively. In this technique the DU 105 calculates the symbol 115 or slot 113 amplitude value and communicates this value to the radio unit 108 prior to transmitting the symbol 115 or slot 113 data to the radio unit 108. This allows the radio unit 108 sufficient time to get the appropriate drain bias state set.

[0104] Figure 8 is a block diagram illustrating another example DSP 136 with radio power control circuitry 169 that selectively disables circuitry in the RF front end unit 126. Within the radio unit 108, often the RF power amplifiers 152 consume a significant percentage of the23 Docket 7069 WO W1 / 376.2178WO01overall radio power consumption. In many cases, this is as much as 80% of the total radio power consumption. Therefore, it may be beneficial to not just achieve power reduction by disabling the RF power amplifier 152 during idle slots 113 and symbols 115, but to also implement techniques to reduce power consumption during active slots 113 and symbols 115. To further optimize power consumption, one technique is to reduce the power amplifier 152 power consumption during active slots 113 and symbols 115 by scaling the power consumption on the basis of the level of the power transmitted during that slot 113 or symbol 115. This could be done in addition to completely disabling the RF amplifier(s) 152 during idle slots 113 and symbols 115 as described previously. For example, this could be done through active control of the drain voltage and / or gate bias of power transistors of the final power amplifiers 152 and driver amplifiers, e.g., in the transmit chain.

[0105] One solution for multi-level drain bias control for a wireless RF power amplifier 152 could be to calculate a symbol -by-symbol RMS signal amplitude of the downlink waveform within the radio unit 108 to generate a discrete index to one of multiple drain bias settings that were then applied on a symbol-by-symbol basis to the transmitter RF power amplifier transistor device or devices, e.g., within the DSP block 136. In contrast, in the present systems and methods, the selection of the drain bias state is determined by control information sent from the gNB (e.g., DU 105) to the radio unit 108 indicating the relative amplitude for each upcoming symbol 115 or slot 113 in advance of the start of the symbol or slot period. Prior to the start of each symbol 115 or slot 113, the gNB (e.g., DU 105) may determine the RMS amplitude of the upcoming symbol 115 or slot 113 and send this information to the radio unit Slot / Symbol Amplitude Register 167. This value allows the radio unit power control block 169 to establish a Bias State Index 165 that corresponds to this amplitude. The function of the Bias State Index 165 is to bin the many possible amplitude levels into a discrete number of bias states. This could be as few as two states, a maximum bias condition used for an upper range of amplitude and a minimum bias condition used for a lower range of amplitude. There could also be a discrete number of intermediate bias states to further subdivide the range of possible corresponding amplitudes in order to further optimize power consumption.

[0106] Each possible value of the Bias State Index 165 may be scaled 187 and used to index several transmitter parameters corresponding to the index. First, the power amplifier drain bias may be scaled and set to a voltage condition that may optimize power consumption for the corresponding range of amplitudes while still maintaining the required linearity24 Docket 7069 WO W1 / 376.2178WO01performance. Second, the power amplitude gate bias may be scaled and set to a voltage condition that set the quiescent drain current that is optimum for the corresponding drain voltage of that bias state. Any pre-driver or driver amplifiers could be similarly controlled in drain and gate bias corresponding to the bias state index to achieve further optimization. Thirdly, since the gain of the PA, driver, and pre-driver amplifiers will likely vary as a function of the gate and drain bias conditions, a TX Gain Control function set within the signal path may compensate for any of the PA 152, driver, and pre-driver gain changes that occur for each bias state. Then fourthly, because the PA 152, driver, and pre-driver AM-to-PM and AM-to-AM characteristics will change as a function of the gate and drain bias conditions, the digital predistortion (DPD) function 191 within the signal chain will also be indexed to one of multiple states corresponding to the Bias State Index. For each of the bias state conditions, the DPD function 191 will include a unique set of look-up tables (LUTs) and DPD coefficients that are adapted periodically to fully linearize the PA, driver, and pre-driver line-up for that specific bias state.

[0107] Figure 9 is a transistor characteristic curve diagram illustrating variable drain bias conditions in a power transistor operating in class AB corresponding to the variable drain voltage regulation in Figure 7 and / or Figure 8. Rather than have infinitely variable bias states, the power amplifier 152 may have a limited number of discrete bias conditions. The slot 113 or symbol 115 amplitudes transmitted from the DU 105 may be binned into one of six different bias states. For each of these bias states, there may be specific gate voltages and / or drain voltages that are set on the power amplifier commensurate with the slot 113 or symbol 115 amplitude. This reduces quiescent bias conditions for low power signals to optimize power consumption while increasing bias conditions for high power signal to maintain linearity performance and achieve the target transmitter power level. And each bias state may index to a different digital pre-distortion (DPD) table (e.g., in a power amplifier gate and / or drain voltage regulator 180) and apply some different transmit power gain control for each different bias state to compensate for any gain variations in the power amplifier 152 with the changing gate and drain voltage settings. For each bias state, there may be a different DPD LUT, a different gain control in the signal path, and a different gate and drain bias condition for the power amplifier. This may optimize the power consumption of the complete transmitter path commensurate with the amplitude of each symbol so that during lightly loaded or empty symbols the power consumption of the transmitter may be adjusted accordingly.25 Docket 7069 WO W1 / 376.2178WO01

[0108] For example, under maximum signal conditions, the drain may be biased according to Bias A condition. For lower and lower signal amplitude conditions, Bias B, C, D, or E voltages may be applied to the drain. Finally, for even lower signal conditions, Bias F voltage may be applied to the drain. While this illustration uses six discrete bias states, the number of bias states used can be set to any number greater than 1 for this technique and this number of states may be set to achieve the best balance between power added efficiency and power amplifier linearity.

[0109] Figure 10 is a waveform diagram illustrating a time-domain representation 1006 of how the drain bias voltage of the transistor may be varied relative to the average power of the transmitted symbol 115 in the configuration of Figure 7 and / or Figure 8. Figure 10 illustrates the drain voltage 1004 in the time domain of a specific symbol. During lightly loaded (Sym 0), the drain voltage 1004 may be low. The next symbol (Syml) would have higher amplitude and a corresponding higher drain voltage 1004. Thus, Figure 10 illustrates how the drain voltage 1004 is adjusted relative to the symbol amplitude relayed from the DU in advance. By getting the amplitude information in advance, the transmitter can queue these different settings and transition between states very quickly. If the radio operates autonomously throughout the symbol period, you have to delay the signal path until you make the amplitude measurement and adjust the power amplifier bias. In contrast, the present systems and methods remove the one symbol latency by getting the amplitude information in advance from the scheduler 171 at the DU 105. Since the scheduler 171 is prior to the IFFT, it can look at all the frequency domain information before it clocks through the FFT and it can instantly know what the amplitude of the symbol at the start of the symbol rather than having to measure across the entire symbol.

[0110] Using this technique, during low load conditions in which very few or none of the user plane resource blocks of the waveform 1006 contain data, then the RMS symbol 115 amplitude will be lower. For these symbols, a low bias voltage will be set to the transistor drain, e.g., as in symbols 0, 2, 4, 7. Whereas when most or all of the resource blocks of the symbols 115 are occupied, the RMS symbol 115 amplitude will be high. Under this condition, a high bias voltage will be set to the transistor drain, e.g., as in symbol 6. During low load conditions when potentially there is no user data traffic in the downlink, only the SSB 117 will be transmitted. During the SSB 117 symbols, the composite signal power transmitted is significantly lower than a fully loaded waveform and the power consumption using this technique will be significantly lower during these symbols. Then during symbols26 Docket 7069 WO W1 / 376.2178WO01115 that contain neither SSB 117 nor user traffic, the quiescent power consumption of the power amplifiers would be at its minimum. Using the symbol-based drain bias control technique applied to a class AB amplifier, the transmitter power consumption will be significantly reduced during low load or no load conditions of the wireless network. To reduce complexity in the drain voltage regulator 182, it may be desirable to limit the number of possible bias conditions.

[0111] Figure 11 is a flow diagram illustrating a method 1100 for reducing power consumption in a radio unit 108. The method 1100 may be implemented by at least a radio unit 108 in a wireless communication system 101. The radio unit 108 be part of a C-RAN 100A implementing a 5G air interface. Alternatively, the method 1100 may be implemented by an RP 106 in a C-RAN 100D implementing a 4G air interface, a macro base station 100C, or another type of non-C-RAN small cell 100B. In some examples, at least a portion of the method 1100 is performed by at least one central unit, such as a DU 105, a CU 103, or a baseband controller 104. The entity or entities may perform the method 1100 using respective processor(s) that execute instructions stored on respective memories.

[0112] The blocks of the flow diagram shown in Figure 11 have been arranged in a generally sequential manner for ease of explanation; however, it is to be understood that this arrangement is merely exemplary, and it should be recognized that the processing associated with method 1100 (and the blocks shown in Figure 11) can occur in a different order (for example, where at least some of the processing associated with the blocks is performed in parallel and / or in an event-driven manner). Also, most standard exception handling is not described for ease of explanation; however, it is to be understood that method 1100 can and typically would include such exception handling.

[0113] The method 1100 begins at optional step 1102 (referred to as the first approach in the third technique above) where, during light traffic conditions, the scheduler 171 (e.g., in the DU 105) schedules / consolidates all user traffic 185 for a frame into the minimum number of slots that already include SSBs 117. Light traffic (in slots with or without SSBs 117), also referred to as reduced traffic conditions, refers to scenarios in which all of the resource blocks in a time period (e.g., frame, subframe 111, slot 113, and / or symbol 115) are not fully loaded. Since the scheduler 171 controls the RB mapping of each upcoming slot 113, it can be programmed to efficiently control the placement of user traffic within the frame and can be provided capability to signal that placement information to the radio unit 108 prior to the start27 Docket 7069 WO W1 / 376.2178WO01of any slot 113. Thus, in step 1102, the scheduler 171 consolidates the user traffic 185 into the slots 113 that already contain SSBs 117 to allow transmitter resources to be shut down during unused slots.

[0114] Step 1102 may include creating, applying, and / or using a scheduler policy that groups all user traffic 185 within a frame into the minimum number of slots 113 that already contain SSBs 117.

[0115] The method 1100 proceeds at optional step 1104 (referred to as the second approach in the third technique above) where, during light traffic conditions, the scheduler 171 (e.g., in the DU 105) schedules / consolidates all user traffic into the minimum number of symbols 115 within the slots 113 that include SSBs 117. In so doing, radio unit resources could be disabled on a symbol-by-symbol basis even within active slots 113.

[0116] Step 1104 may include creating, applying, and / or using a scheduler policy that groups all user traffic 185 within a frame into the minimum number of symbols 115 that already contain SSBs 117. A scheduler policy that groups all the user traffic into the same symbols where there are also SSBs allows the transmitter to shut off completely for more symbols compared to if that user traffic were scattered across the whole slot period and you have to keep the entire transmitter active through the whole slot.

[0117] Therefore, during conditions of reduced or light user traffic 185A-D, by consolidating the user traffic 185A-D into slots 113 (optional step 1102) and / or symbols 115 (optional step 1104) that already contain SSBs 117 and consolidating into the minimum number of slots 113 and symbols 115, this allows the radio unit 108 to disable certain circuitry during idle slots 113 and symbols 115 to minimize power consumption.

[0118] The method 1100 proceeds at optional step 1106 where the RU 108 triggers at least one power reduction step in response to receiving information from at least one DU 105 indicating activity level of at least one slot 113 and / or symbol 115. This information may explicitly or implicitly identify empty slots 113 and / or explicitly indicate transmit power per slot 113 or symbol 115 (e.g., as calculated by the scheduler 171). Additionally or alternatively, a bitmask may be used in which each bit may correspond to a slot 113 in a particular subframe 111. Additionally or alternatively, the information may identify the last non-empty slot 113 in a particular subframe 111 or the first empty slot 113 in a particular subframe 111. The information indicating activity level could be sent using managementplane (“M-plane”) communications or control-plane (“C-plane”) communications, e.g., an O-28 Docket 7069 WO W1 / 376.2178WO01RAN “transmission blanking” mechanism in which Section Type 0 messaging is used by the DU 105 to indicate to the RU 108 that certain slot(s) 113 or symbol(s) 115 will not be used (idle periods, guard periods).

[0119] In C-RAN 100A, 100D examples, the RU 108 may be one of a plurality of RUs 108 (or RPs 106). In non-C-RAN small cell 100B or macro base station 100C examples, the base station may include a single radio. In a C-RAN 100 A, 100D configuration, power reduction could be triggered by the CU 103 and / or DU(s) 105 in 5G configurations or a baseband controller 104 in 4G configurations. For example, the CU 103, DU(s) 105, or baseband controller 104 in a C-RAN 100 A may be configured to identify situations with light user traffic or no traffic, which could benefit from power reduction step(s). Alternatively, the power reduction step(s) may be triggered at the RU 108 or an external management system 114. In C-RAN 100A, 100D configurations, the method 1100 may be performed in parallel for multiple or all RUs 108 in the same C-RAN 100A, 100D. In 5G configurations, message(s) can be sent, from the CU 103, DU(s) 105, or baseband controller 104, across the M-plane to the RUs 108 (or RPs 106) and, optionally, then on to the UE(s) 110, e.g., using radio resource control (RRC) signaling.

[0120] The method 1100 proceeds at step 1108 (referred to as the first technique above) where the RU 108 disables component(s) of the DSP (e.g., fronthaul packet interface, the low PHY processing, the DFE (digital front end), and / or digital up conversion (DUC) circuitry), and / or the RF front end (e.g., RF upconverter and / or power amplifiers) during the slots 113 that do not contain active SSB 117 transmissions (e.g., slots 4-9 in the example of Figure 2). The RU 108 may further enable or activate these component(s) / circuit blocks only during slots 113 that contain active SSBs 117 (e.g., slots 0-3 in the example of Figure 2). In this manner, the radio unit transmitter blocks would be enabled or disabled on a slot-by-slot basis. In step 1108 the scheduler function 171 of the gNB baseband would signal to the radio unit 108 prior to the start of a slot 113 period whether or not it contains any active transmissions, either SSBs 117 or user traffic 185. This allows the radio unit 108 to accurately time the disabling of the circuit blocks of idle slots and to enable the blocks at the appropriate time for active slots 113.

[0121] The method 1100 proceeds at step 1110 (referred to as the second technique above) where the RU 108 disables component s) of the DSP (e.g., fronthaul packet interface, the low PHY processing, the DFE (digital front end), and / or digital up conversion (DUC) circuitry),29 Docket 7069 WO W1 / 376.2178WO01and / or the RF front end (e.g., RF upconverter and / or power amplifiers) during the symbols 115 that do not contain active SSB 117 transmissions. The RU 108 may further enable or activate these component(s) / circuit blocks only during symbols 115 that contain active SSBs 117. In this manner, the radio unit transmitter blocks would be enabled or disabled on a symbol -by-symbol basis. In step 1110 the scheduler function 171 of the gNB baseband would signal to the radio unit 108 prior to the start of a symbol 115 period whether or not it contains any active transmissions, either SSBs 117 or user traffic 185. This allows the radio unit 108 to accurately time the disabling of the circuit blocks of idle slots and to enable the blocks at the appropriate time for active symbols 115.

[0122] The method 1100 proceeds at optional step 1112 (referred to as the fourth technique above) where, for at least one amplifier circuit in the RU 108, the RU 108 limits a voltage bias of a drain and / or a gate of the respective at least one amplifier circuit based on an average amplitude of a signal being transmitted, e.g., as outlined in any of Figures 7-10. Optional step 1112 may alternatively be referred to as average power drain control. In other words, the RU 108 detects the average power of a signal being transmitted, then adjusts the drain and / or gate voltage of the at least one amplifier circuit accordingly. For example, as the amplitude of the signal being transmitted is reduced (in response to interference reducing from light traffic), the bias voltage of the drain and / or gate of the at least one amplifier can be reduced proportionally. Therefore, optional step 1112 may reduce unnecessary power dissipation by operating the at least one amplifier at a lower bias. Optional step 1112 may be used to adjust the bias voltage of gate(s) and / or drain(s) in a final power amplifier stage, a pre-amplifier, and / or driver amplifier stage(s), e.g., in a transmit chain of an RU 108.

[0123] The additional circuitry being disabled in optional step 1112 (and / or other steps) may include (1) entire receive chain(s) and / or transmit chain(s) processing signals for the disabled at least one antenna 122; or (2) merely low-noise amplifier(s) and / or power amplifier(s) in the receive chain(s) and transmit chain(s), respectively, processing signals for the disabled at least one additional antenna 122; or (3) any combination of components in the receive chain and / or transmit chain processing signals for the disabled at least one additional antenna 122.

[0124] While not explicitly shown in Figure 11, the method 1100 may also include the RU 108 periodically disabling at least one additional antenna 122 used to transmit the wireless signals from the RU 108, along with at least some additional circuitry used to process the30 Docket 7069 WO W1 / 376.2178WO01wireless signals for the at least one additional antenna 122. The method may also include reducing the speed of at least one fan or the number of fans operating in the RU 108 based on temperature(s) of at least one component in the RU 108 falling below respective threshold(s). For example, the DC voltage applied to fan(s) may be reduced or pulse width modulation may be used to reduce the speed of fan(s).

[0125] Figure 12A is a circuit diagram illustrating an example RF amplifier circuit 1200A comprising a MESFET (e.g., GaAs) transistor 194 (also referred to as a power transistor herein). For example, the RF amplifier circuit 1200A may be located in a power amplifier 152. In the example RF amplifier circuit 1200A in Figure 12A, the transistor 194 may receive an input at the gate and output an amplified signal at the drain, where the source is coupled to ground. The RF amplifier circuit 1200 A includes impedance matching circuits 192A-B at the transistor input (gate) and output (drain) to best match the source and load impedance of the transistor 194 to optimize either the circuit 1200 A gain, output power, or linearity depending on the specific requirements. A gate bias voltage, VG, is applied to the gate of the transistor 194 through a quarter- wavelength transmission line 198 A (quarter- wave transformer for impedance transformation) to prevent the low DC impedance of the VG source from loading the high frequency RF response. Likewise, a drain bias voltage, VDD, is applied to the transistor drain through a quarter- wavelength transmission line 198B (quarter- wave transformer for impedance transformation) to prevent the low DC impedance of the VDD source from loading the high frequency RF response. In the circuit 1200A of Figure 12A, the gate voltage and drain voltage as set to fixed voltage levels. The gate voltage, VG, is set based upon whether the circuit 1200A is set for Class A or Class AB operation.

[0126] Figure 12B is a circuit diagram illustrating another example RF amplifier circuit 1200B comprising a MESFET (e.g., GaAs) transistor 194. In contrast to Figure 12A, the example RF amplifier circuit 1200B in Figure 12B implements a variable drain voltage regulator 197 and / or a variable gate voltage regulator 196. Specifically, in the circuit 1200B of Figure 12B, the fixed gate and drain voltages are replaced with variable voltage regulators 196, 197 having a fixed primary voltage and a control interface used to adjust the secondary voltage to variable states. The variable secondary voltage (output of the variable drain voltage regulator 197) is then applied to the transistor drain to implement drain bias control. Similarly, the variable secondary voltage (output of the variable gate voltage regulator 196) is31 Docket 7069 WO W1 / 376.2178WO01then applied to the transistor gate to implement gate bias control. Although the example RF amplifier circuit 1200B is based on a type of field-effect transistor (MESFET), this same technique is directly applicable to bipolar junction transistors (BJT). In the case of a BJT, the drain and references to drain, drain voltage and drain current would be replaced with the collector, collector voltage, and collector current, respectively. Likewise, references to gate, gate voltage, and gate current would be replaced with the base, base voltage, and base current, respectively in a BJT. Similarly, references to source, source voltage, and source current would be replaced with the emitter, emitter voltage, and emitter current, respectively in a BJT. As an example the variable drain voltage regulator 197 and / or the variable gate voltage regulator 196 in Figure 12B may be the same or different than the variable drain voltage regulator 197 and / or the variable gate voltage regulator 196 in Figure

[0127] The methods and techniques described here may be implemented in digital electronic circuitry, field programmable gate array (FPGA), or with a programmable processor (for example, a special-purpose processor or a general-purpose processor such as a computer) firmware, software, or in combinations of them. Apparatus embodying these techniques may include appropriate input and output devices, field programmable gate array (FPGA), a programmable processor, and a storage medium tangibly embodying program instructions for execution by the programmable processor. A process embodying these techniques may be performed by a programmable processor executing a program of instructions to perform desired functions by operating on input data and generating appropriate output. The techniques may advantageously be implemented in one or more programs that are executable on a programmable system including at least one programmable processor coupled to receive data and instructions from, and to transmit data and instructions to, a data storage system, at least one input device, and at least one output device. Generally, a processor will receive instructions and data from a read-only memory and / or a random access memory. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks and removable disks; magneto-optical disks; and DVD disks. Any of the foregoing may be supplemented by, or incorporated in, specially designed application-specific integrated circuits (ASICs).

[0128] Terminology32 Docket 7069 WO W1 / 376.2178WO01

[0129] Brief definitions of terms, abbreviations, and phrases used throughout this application are given below.

[0130] The term “determining” and its variants may include calculating, extracting, generating, computing, processing, deriving, modeling, investigating, looking up (e.g., looking up in a table, a database, or another data structure), ascertaining and the like. Also, “determining” may also include receiving (e.g., receiving information), accessing (e.g., accessing data in a memory) and the like. Also, “determining” may include resolving, selecting, choosing, establishing and the like.

[0131] The phrase “based on” does not mean “based only on,” unless expressly specified otherwise. In other words, the phrase “based on” describes both “based only on” and “based at least on”. Additionally, the term “and / or” means “and” or “or”. For example, “A and / or B” can mean “A”, “B”, or “A and B”. Additionally, “A, B, and / or C” can mean “A alone,” “B alone,” “C alone,” “A and B,” “A and C,” “B and C” or “A, B, and C.”

[0132] The terms “connected”, “coupled”, and “communicatively coupled” and related terms may refer to direct or indirect connections. If the specification states a component or feature “may,” “can,” “could,” or “might” be included or have a characteristic, that particular component or feature is not required to be included or have the characteristic.

[0133] The terms “responsive” or “in response to” may indicate that an action is performed completely or partially in response to another action. The term “module” refers to a functional component implemented in software, hardware, or firmware (or any combination thereof) component.

[0134] The methods disclosed herein comprise one or more steps or actions for achieving the described method. Unless a specific order of steps or actions is required for proper operation of the method that is being described, the order and / or use of specific steps and / or actions may be modified without departing from the scope of the claims.

[0135] In conclusion, the present disclosure provides novel systems, methods, and arrangements for reducing radio unit power consumption based on centralized unit control. While detailed descriptions of one or more configurations of the disclosure have been given above, various alternatives, modifications, and equivalents will be apparent to those skilled in the art without varying from the spirit of the disclosure. For example, while the configurations described above refer to particular features, functions, procedures, components, elements, and / or structures, the scope of this disclosure also includes33 Docket 7069 WO W1 / 376.2178WO01configurations having different combinations of features, functions, procedures, components, elements, and / or structures, and configurations that do not include all of the described features, functions, procedures, components, elements, and / or structures. Accordingly, the scope of the present disclosure is intended to embrace all such alternatives, modifications, and variations as fall within the scope of the claims, together with all equivalents thereof. Therefore, the above description should not be taken as limiting.Examples

[0136] Example 1 includes a base station for reducing power consumption in a radio unit, comprising: at least one processor configured to: during light traffic conditions, schedule all user traffic for a frame into a minimum number of slots that include synchronization signal block (SSB) traffic; trigger at least one power reduction step for the radio unit in response to receiving information from at least one centralized unit indicating activity level for at least one slot or symbol.

[0137] Example 2 includes the base station of Example 1, further comprising, during light traffic conditions, schedule all user traffic for a frame or a slot into a minimum number of symbols that include SSB traffic.

[0138] Example 3 includes the base station of any of Examples 1-2, wherein the information is sent via management plane signaling.

[0139] Example 4 includes the base station of any of Examples 1-3, wherein the information is sent via control plane signaling.

[0140] Example 5 includes the base station of Example 4, wherein the control plane signaling utilizes 0-RAN transmission blanking using Section Type 0 to indicate to the radio unit that certain slots or symbols will be empty.

[0141] Example 6 includes the base station of any of Examples 1-5, wherein the at least one power reduction step comprises disabling at least one component of a digital signal processor, a radio frequency front end unit, or both, that do not contain SSB traffic.

[0142] Example 7 includes the base station of any of Examples 1-6, wherein the at least one processor is further configured to, for each of at least one amplifier circuit in the radio unit, limit a voltage bias of a drain, a gate, or both, of the respective amplifier circuit based on an average amplitude of a signal being transmitted.34 Docket 7069 WO W1 / 376.2178WO01

[0143] Example 8 includes the base station of Example 7, wherein the at least one amplifier circuit comprises one or more of the following: a final power amplifier stage, a pre-amplifier, and one or more driver amplifier stages in a transmit chain of the radio unit.

[0144] Example 9 includes the base station of any of Examples 1-8, wherein the base station is a cloud radio access network (C-RAN) implementing a Fifth Generation New Radio (5GNR) wireless interface, comprising: the radio unit and a plurality of additional radio units, each being configured to exchange radio frequency (RF) signals with at least one user equipment (UE); and the centralized unit communicatively coupled to the radio unit and the plurality of additional radio units via a fronthaul network, wherein the centralized unit is a Distributed Unit (DU) or a Central Unit (CU) configured to operate in a 3 GPP Fifth Generation communication system.

[0145] Example 10 includes the base station of any of Examples 1-9, wherein the base station is a distributed access system (DAS) implementing a Fourth Generation (4G) or Fifth Generation New Radio (5G NR) wireless interface, comprising: the radio unit and a plurality of additional radio units, each being configured to exchange radio frequency (RF) signals with at least one user equipment (UE); and the centralized unit communicatively coupled to the radio unit and the plurality of additional radio units via a fronthaul network, wherein the centralized unit is a head unit, wherein the head unit is communicatively coupled to a Distributed Unit (DU) via an 0-RAN interface.

[0146] Example 11 includes a method for reducing power consumption in a radio unit in a base station, comprising: during light traffic conditions, scheduling all user traffic for a frame into a minimum number of slots that include synchronization signal block (SSB) traffic; triggering at least one power reduction step for the radio unit in response to receiving information from at least one centralized unit indicating activity level for at least one slot or symbol.

[0147] Example 12 includes the method of Example 11, further comprising, during light traffic conditions, scheduling all user traffic for a frame or a slot into a minimum number of symbols that include SSB traffic.

[0148] Example 13 includes the method of any of Examples 11-12, wherein the information is sent via management plane signaling.

[0149] Example 14 includes the method of any of Examples 11-13, wherein the information is sent via control plane signaling.35 Docket 7069 WO W1 / 376.2178WO01

[0150] Example 15 includes the method of Example 14, wherein the control plane signaling utilizes O-RAN transmission blanking using Section Type 0 to indicate to the radio unit that certain slots or symbols will be empty.

[0151] Example 16 includes the method of any of Examples 11-15, wherein the at least one power reduction step comprises disabling at least one component of a digital signal processor, a radio frequency front end unit, or both, that do not contain SSB traffic.

[0152] Example 17 includes the method of any of Examples 11-16, further comprising, for each of at least one amplifier circuit in the radio unit, limit a voltage bias of a drain, a gate, or both, of the respective amplifier circuit based on an average amplitude of a signal being transmitted.

[0153] Example 18 includes the method of Example 17, where the at least one amplifier circuit comprises one or more of the following: a final power amplifier stage, a pre-amplifier, and one or more driver amplifier stages in a transmit chain of the radio unit.

[0154] Example 19 includes the method of any of Examples 11-18, wherein the base station is a cloud radio access network (C-RAN) implementing a Fifth Generation New Radio (5GNR) wireless interface, comprising: the radio unit and a plurality of additional radio units, each being configured to exchange radio frequency (RF) signals with at least one user equipment (UE); and the centralized unit communicatively coupled to the radio unit and the plurality of additional radio units via a fronthaul network, wherein the centralized unit is a Distributed Unit (DU) or a Central Unit (CU) configured to operate in a 3 GPP Fifth Generation communication system.

[0155] Example 20 includes the method of any of Examples 11-19, wherein the base station is a distributed access system (DAS) implementing a Fourth Generation (4G) or Fifth Generation New Radio (5G NR) wireless interface, comprising: the radio unit and a plurality of additional radio units, each being configured to exchange radio frequency (RF) signals with at least one user equipment (UE); and the centralized unit communicatively coupled to the radio unit and the plurality of additional radio units via a fronthaul network, wherein the centralized unit is a head unit, wherein the head unit is communicatively coupled to a Distributed Unit (DU) via an O-RAN interface.36 Docket 7069 WO W1 / 376.2178WO01

Claims

CLAIMS1. A base station for reducing power consumption in a radio unit, comprising:at least one processor configured to:during light traffic conditions, schedule all user traffic for a frame into a minimum number of slots that include synchronization signal block (SSB) traffic; andtrigger at least one power reduction step for the radio unit in response to receiving information from at least one centralized unit indicating activity level for at least one slot or symbol.

2. The base station of claim 1, further comprising, during light traffic conditions, schedule all user traffic for a frame or a slot into a minimum number of symbols that include SSB traffic.

3. The base station of claim 1, wherein the information is sent via management plane signaling.

4. The base station of claim 1, wherein the information is sent via control plane signaling.

5. The base station of claim 4, wherein the control plane signaling utilizes O-RAN transmission blanking using Section Type 0 to indicate to the radio unit that certain slots or symbols will be empty.

6. The base station of claim 1, wherein the at least one power reduction step comprises disabling at least one component of a digital signal processor, a radio frequency front end unit, or both, that do not contain SSB traffic.

7. The base station of claim 1, wherein the at least one processor is further configured to, for each of at least one amplifier circuit in the radio unit, limit a voltage bias of a drain, a gate, or both, of the respective amplifier circuit based on an average amplitude of a signal being transmitted.37 Docket 7069 WO W1 / 376.2178WO018. The base station of claim 7, wherein the at least one amplifier circuit comprises one or more of the following: a final power amplifier stage, a pre-amplifier, and one or more driver amplifier stages in a transmit chain of the radio unit.

9. The base station of claim 1, wherein the base station is a cloud radio access network (C-RAN) implementing a Fifth Generation New Radio (5G NR) wireless interface, comprising:the radio unit and a plurality of additional radio units, each being configured to exchange radio frequency (RF) signals with at least one user equipment (UE); andthe at least one centralized unit communicatively coupled to the radio unit and the plurality of additional radio units via a fronthaul network, wherein the at least one centralized unit is a Distributed Unit (DU) or a Central Unit (CU) configured to operate in a 3GPP Fifth Generation communication system.

10. The base station of claim 1, wherein the base station is a distributed access system (DAS) implementing a Fourth Generation (4G) or Fifth Generation New Radio (5G NR) wireless interface, comprising:the radio unit and a plurality of additional radio units, each being configured to exchange radio frequency (RF) signals with at least one user equipment (UE); andthe at least one centralized unit communicatively coupled to the radio unit and the plurality of additional radio units via a fronthaul network, wherein the at least one centralized unit is a head unit, wherein the head unit is communicatively coupled to a Distributed Unit (DU) via an 0-RAN interface.

11. A method for reducing power consumption in a radio unit in a base station, comprising:during light traffic conditions, scheduling all user traffic for a frame into a minimum number of slots that include synchronization signal block (SSB) traffic; andtriggering at least one power reduction step for the radio unit in response to receiving information from at least one centralized unit indicating activity level for at least one slot or symbol.38 Docket 7069 WO W1 / 376.2178WO0112. The method of claim 11, further comprising, during light traffic conditions, scheduling all user traffic for a frame or a slot into a minimum number of symbols that include SSB traffic.

13. The method of claim 11, wherein the information is sent via management plane signaling.

14. The method of claim 11, wherein the information is sent via control plane signaling.

15. The method of claim 14, wherein the control plane signaling utilizes O-RAN transmission blanking using Section Type 0 to indicate to the radio unit that certain slots or symbols will be empty.

16. The method of claim 11, wherein the at least one power reduction step comprises disabling at least one component of a digital signal processor, a radio frequency front end unit, or both, that do not contain SSB traffic.

17. The method of claim 11, further comprising, for each of at least one amplifier circuit in the radio unit, limit a voltage bias of a drain, a gate, or both, of the respective amplifier circuit based on an average amplitude of a signal being transmitted.

18. The method of claim 17, wherein the at least one amplifier circuit comprises one or more of the following: a final power amplifier stage, a pre-amplifier, and one or more driver amplifier stages in a transmit chain of the radio unit.

19. The method of claim 11, wherein the base station is a cloud radio access network (C-RAN) implementing a Fifth Generation New Radio (5GNR) wireless interface, comprising:the radio unit and a plurality of additional radio units, each being configured to exchange radio frequency (RF) signals with at least one user equipment (UE); andthe at least one centralized unit communicatively coupled to the radio unit and the plurality of additional radio units via a fronthaul network, wherein the at least one centralized unit is a Distributed Unit (DU) or a Central Unit (CU) configured to operate in a 3GPP Fifth Generation communication system.39 Docket 7069 WO W1 / 376.2178WO0120. The method of claim 11, wherein the base station is a distributed access system (DAS) implementing a Fourth Generation (4G) or Fifth Generation New Radio (5G NR) wireless interface, comprising:the radio unit and a plurality of additional radio units, each being configured to exchange radio frequency (RF) signals with at least one user equipment (UE); andthe at least one centralized unit communicatively coupled to the radio unit and the plurality of additional radio units via a fronthaul network, wherein the at least one centralized unit is a head unit, wherein the head unit is communicatively coupled to a Distributed Unit (DU) via an 0-RAN interface.40 Docket 7069 WO W1 / 376.2178WO01

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