Control device, wireless access network node, wireless terminal, and methods thereof

Abstract

This control device selectively applies any of a plurality of downlink discontinuous transmission (DTX) patterns to a radio access network (RAN) node. The plurality of downlink DTX patterns are different from each other in terms of the numbers of subframes in which downlink transmission by the RAN node is stopped in a radio frame. This enables the RAN node to use, for example, one selected from a plurality of downlink DTX patterns in which the numbers of subframes in which downlink transmission by the RAN node is stopped in the radio frame are different from each other.

Description

CONTROL DEVICE, RADIO ACCESS NETWORK NODE, RADIO TERMINAL, AND METHODS THEREOF

[0001] The present disclosure relates to a controller, a radio access network node, a wireless terminal, and methods thereof.

[0002] Non-Patent Document 1 discloses potential solutions for energy conservation in an Evolved Universal Terrestrial Radio Access Network (E-UTRAN), i.e., a Long Term Evolution (LTE) network. Section 7 of Non-Patent Document 1 describes several solutions for intra-eNB energy saving. One of these solutions is to configure Multimedia Broadcast / Multicast Service (MBMS) over a Single Frequency Network (MBSFN) subframes within the range supported by current specification limitations. The term "MBSFN" may be an abbreviation for Multicast-broadcast single-frequency network (MBSFN). Because MBSFN subframes have fewer Cell-specific Reference Signals (CRS) than regular subframes, configuring MBSFN subframes whenever possible can reduce eNB transmission times. Current 3rd Generation Partnership Project (3GPP®) specifications allow up to five MBSFN subframes in a single radio frame in Time Division Duplex (TDD) LTE systems and up to six MBSFN subframes in Frequency Division Duplex (FDD) LTE systems. Utilizing currently available MBSFN subframes is an effective method for energy-efficient network operation in LTE, potentially achieving energy savings on the order of 30-50% in typical traffic scenarios compared to operation without MBSFN subframes. This solution is already supported without any impact on the current 3GPP specifications.

[0003] Non-Patent Document 2 discusses the possibility of introducing enhanced cell discontinuous transmission (DTX). Non-Patent Document 2 points out that the main contributor to downlink transmission time in LTE normal subframes is the CRS transmitted in every subframe. Similar to Non-Patent Document 1, Non-Patent Document 2 mentions that the use of MBSFN subframes can reduce the eNB's transmission-time fraction. However, Non-Patent Document 2 notes that the potential benefit of using MBSFN subframes is limited by the fact that even in MBSFN subframes, the CRS must be transmitted in at least one Orthogonal Frequency Division Multiplexing (OFDM) symbol per subframe. To address this issue, Non-Patent Document 2 proposes using SSS instead of CRS for UE mobility measurements used in cell search, thereby reducing the number of CRSs in empty cells with no active terminals (i.e., User Equipments (UEs)). Non-Patent Documents 3-5 provide further discussion of the CRS reduction and the use of SSS measurements instead of CRS measurements proposed in Non-Patent Document 2.

[0004] Currently, 3GPP is discussing network energy saving for 3GPP Release 18 (see, for example, Non-Patent Document 6). Network energy saving is abbreviated as NES. As described in Non-Patent Document 6, there are various techniques for improving network energy saving, including cell DTX and discontinuous reception (DRX). In one example, the network may provide a mechanism to notify UEs in a cell whether the cell is in an inactive state. During cell DTX or cell DRX, i.e., while the cell is in an inactive state, the cell may not transmit or receive, or may maintain only limited transmission or reception.

[0005] For example, as described in Section 6.1 of Non-Patent Document 6, when cell DTX is activated, a 5G NR cell does not need to transmit some periodic signals and channels, such as cell-common channels and UE-specific channels. These periodic signals and channels include, for example, Synchronization Signal (SS) / Physical Broadcast Channel (PBCH) block (SSB), System Information (SI), paging, and the cell-common Physical Downlink Control Channel (PDCCH). The transmission patterns of these periodic signals and channels can be semi-statically or dynamically adapted. Adapting the transmission pattern includes changing the periodicity, changing the location of time resources, and omitting certain signals or channels. In one example, in one transmission pattern, the repetition period of SSB and System Information Block Type 1 (SIB1) is extended to 40 ms, and only the Primary Synchronization Signal (PSS) and Secondary Synchronization Signal (SSS) are transmitted in the remaining 20 ms.

[0006] The Open Radio Access Network (O-RAN) Alliance is conducting technical studies on architectures including a Non-Real-Time (Non-RT) RAN Intelligent Controller (RIC) and a Near-RT RIC, and is providing technical specifications for these. The O-RAN Working Group 1 (WG1) is defining the overall O-RAN architecture and use cases. These use cases include the energy saving (ES) use case (see, for example, Section 4.21 of Non-Patent Document 7 and Non-Patent Document 8). The ES use case includes three sub-use cases: carrier and cell switch off / on, radio frequency (RF) channel switch off / on, and Advanced Sleep Mode.

[0007] In the carrier and cell switch off / on sub-use case, both the controlling system and the controlled system have non-real-time timescales. The Non-RT RIC provides carrier and cell switch off / on parameter configurations to E2 nodes (e.g., O-eNB, O-Central Unit (CU), O-Distributed Unit (DU)) using the O1 interface. The Non-RT RIC also provides carrier and cell switch off / on parameter configurations to O-Radio Units (RUs) via the Open Fronthaul Management plane (M-plane). A Non-RT RIC application (rApp) hosted on the Non-RT RIC may host a trained Machine Learning (ML) model and be used to achieve optimized ES configurations, such as switching times, that can provide the optimal desired tradeoff between ES and user Quality of Service (QoS).

[0008] The RF channel switch off / on sub-use case has a first non-real-time implementation and a second near-real-time implementation. In the first non-real-time implementation, the Non-RT RIC configures the user's QoS to the E2 node (e.g., O-eNB, O-CU, O-DU) using the O1 interface and provides massive multiple-input multiple-output (MIMO) system reconfiguration to the O-RU via the Open Fronthaul M-plane. In the second near-real-time implementation, the Non-RT RIC provides the trained ML model to the Near-RT RIC via the A1 interface. The Near-RT RIC application (xApp) hosted on the Near-RT RIC optimizes the RF channel configuration by performing inference using the trained ML model and provides the optimized RF channel configuration to the E2 node (e.g., O-eNB, O-CU, O-DU) via the E2 interface. The E2 node then performs massive MIMO system reconfiguration to the O-RU via the Open Fronthaul M-plane.

[0009] Advanced Sleep Modes (ASMs) are used to reduce energy consumption (EC) by automatically turning off parts of the O-RU components for one symbol (ASM1), one slot (ASM2), or one frame (ASM3). The objective of this sub-use case is to maximize the duration of ASMs (and the corresponding ES) during which O-RU components are switched off, taking into account user QoS constraints on latency. To this end, ASM activation policies can be set (e.g., the order and number of ASMs at each level), and system configurations can be applied (e.g., setting SSB periodicity; compressing data transmission in certain slots and leaving the remaining slots "in a sleep state" empty; reducing synchronization signal transmissions, reducing random access and paging opportunities, etc.). The Near-RT RIC requests the ML model over the A1 interface. Once this ML model is deployed and activated, the Near-RT RIC optimizes ES by setting the ASM policy and system configuration over the E2 interface and the Open Fronthaul M-plane. The xApp in the Near-RT RIC uses the trained ML model to infer ASM activation policies and system configurations and provides them to the E2 nodes (e.g., O-eNB, O-CU, O-DU) via the E2 interface. The E2 nodes send ASM and system parameters to the O-RU via the Open Fronthaul M-plane.

[0010] Patent Literature 1 discloses that a base station monitors the remaining capacity of a battery that supplies power to the base station, and if the actual battery remaining capacity is lower than the planned battery remaining capacity, sets control parameters that are more effective in saving power depending on the insufficient battery remaining capacity. The control parameters may set the suspension of transmission and reception functions during time periods when no bandwidth is allocated in the uplink or downlink. Alternatively, the control parameters may cause the suspension of transmission and reception operations for an entire frame if even scheduling information regarding bandwidth allocation is not transmitted. Various techniques and control parameters are available for achieving sleep control or suspension of transmission and reception operations depending on the target wireless standard.

[0011] Japanese Patent Application Laid-Open No. 2012-253621

[0012] 3GPP TR 36.927 V17.0.0 (2022-04), "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Potential solutions for energy saving for E-UTRAN (Release 17)", April 2022Ericsson, ST-Ericsson, "Extended cell DTX for enhanced energy-efficient network operation", R1-095011, 3GPP TSG-RAN WG1 #59, Jeju, Korea, November 9 - 13, 2009Samsung, "Considerations on Extended Cell DTX", R1-100144, 3GPP TSG RAN WG1 #59bis, Valencia, Spain, January 18 - 22, 2010Ericsson, ST-Ericsson, "Enabling Enhanced Cell DTX in LTE", R1-101309, 3GPP TSG-RAN WG1 #60, San Francisco, USA, February 22 - 26, 2010Ericsson, ST-Ericsson, "UE impacts of Cell DTX in LTE", R1-101552, 3GPP TSG-RAN WG1 #60, San Francisco, USA, February 22 - 26, 20103GPP TR 38.864 V18.1.0 (2023-03) "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Study on network energy savings for NR (Release 18)", March 2023O-RAN ALLIANCE Working Group 1, "O-RAN Use Cases Analysis Report 12.0", O-RAN.WG1.Use-Cases-Analysis-Report-R003-v12.00, October 2023O-RAN ALLIANCE Working Group 1, "O-RAN Network Energy Saving Use Cases Technical Report 2.0", O-RAN.WG1.Network-Energy-Savings-Technical-Report-R003-v02.00, June 2023.

[0013] Non-Patent Documents 2-5 teach cell DTX techniques involving halting downlink transmissions, including CRS transmissions, in MBSFN subframes within a radio frame. However, these documents do not explicitly disclose the use of multiple downlink DTX patterns in which transmission is halted in different numbers of subframes within a radio frame. Other documents cited in the Background Art section also do not explicitly disclose this. It may be useful to selectively use multiple downlink DTX patterns in which transmission is halted in different numbers of subframes within a radio frame depending on certain conditions, such as, but not limited to, the power supply status of a base station (e.g., eNB). Therefore, an alternative or improved method for enabling this may be needed.

[0014] One of the objectives that the embodiments disclosed in this specification aim to achieve is to provide an apparatus, a method, and a program that contribute to solving at least one of the problems, including the problems described above. It should be noted that this objective is only one of the objectives that the embodiments disclosed in this specification aim to achieve. Other objectives or objectives and novel features will become apparent from the description of this specification or the accompanying drawings.

[0015] In a first aspect, the controller is configured to selectively apply one of a plurality of downlink DTX patterns to a radio access network node, the downlink DTX patterns differing from one another in the number of subframes within a radio frame during which downlink transmission by the radio access network node is suspended.

[0016] In a second aspect, a method performed by a controller includes selectively applying to a radio access network node one of a plurality of downlink DTX patterns, the downlink DTX patterns differing from one another in a radio frame in the number of subframes during which downlink transmission by the radio access network node is suspended.

[0017] In a third aspect, a radio access network node is configured to selectively use one of a plurality of downlink DTX patterns, the downlink DTX patterns differing from one another in the number of subframes within a radio frame during which downlink transmission by the radio access network node is suspended.

[0018] In a fourth aspect, a method performed by a radio access network node comprises selectively using one of a plurality of downlink DTX patterns, the downlink DTX patterns differing from one another in the number of subframes within a radio frame during which downlink transmission by the radio access network node is suspended.

[0019] In a fifth aspect, the wireless terminal is configured to receive configuration information from a radio access network node indicating a selected one of a plurality of downlink DTX patterns, and to receive downlink transmissions of the radio access network node based on the configuration information, the plurality of downlink DTX patterns differing from one another in a radio frame in the number of subframes during which downlink transmissions by the radio access network node are suspended.

[0020] In a sixth aspect, a method performed by a wireless terminal includes receiving configuration information from a radio access network node indicating a selected one of a plurality of downlink DTX patterns, and receiving downlink transmissions of the radio access network node based on the configuration information, the plurality of downlink DTX patterns differing from one another in a radio frame in a number of subframes during which downlink transmissions by the radio access network node are suspended.

[0021] In a seventh aspect, a program includes a group of instructions (software code) that, when loaded into a computer, causes the computer to perform a method according to any one of the above aspects.

[0022] According to the above-described aspects, it is possible to provide an apparatus, a method, and a program that contribute to solving at least one of a plurality of problems including the above-described problem.

[0023] 1 illustrates an example configuration of a wireless communication system according to one or more embodiments; 2 illustrates an example flow chart of an operation of a control device (e.g., a RAN controller), according to one or more embodiments; 3 illustrates a sequence diagram of an example operation of a UE, a RAN node, and a control device, according to one or more embodiments; 4 illustrates an example of multiple downlink DTX patterns, according to one or more embodiments; 5 illustrates an example of suspending transmission within a subframe, according to one or more embodiments; 6 illustrates an example of suspending transmission within a subframe, according to one or more embodiments; 7 illustrates a flowchart of an example operation of a control device, according to one or more embodiments; 8 illustrates an example of switching between multiple downlink DTX patterns, according to one or more embodiments; 9 illustrates a sequence diagram of example signaling, according to one or more embodiments; 10 illustrates a block diagram of an example UE, according to one or more embodiments; 11 illustrates a block diagram of an example RAN node, according to one or more embodiments; 12 illustrates a block diagram of an example control device, according to one or more embodiments;

[0024] Hereinafter, specific embodiments will be described in detail with reference to the drawings. In each drawing, the same or corresponding elements are designated by the same reference numerals, and for clarity of explanation, duplicate explanations will be omitted as necessary.

[0025] The multiple embodiments described below may be used independently, or two or more embodiments may be combined as appropriate. These multiple embodiments may have different novel features. Therefore, these multiple embodiments may contribute to achieving different objectives or solving different problems, and may contribute to achieving different effects.

[0026] Each drawing is merely an example for describing one or more embodiments. Each drawing may not relate to only one particular embodiment, but may also relate to one or more other embodiments. As will be understood by those skilled in the art, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings to create, for example, an embodiment not explicitly shown or described. Not all features or steps shown in any one drawing are necessary to describe an exemplary embodiment, and some features or steps may be omitted. The order of steps described in any drawing may be changed as appropriate.

[0027] The following embodiments are described primarily for the 3GPP LTE (or E-UTRAN) system, but may also be applied to other wireless communication systems.

[0028] As used herein, depending on the context, "if" may be interpreted to mean "when," "while," "at or around the time," "after," "upon," "in response to determining," "in accordance with a determination," or "in response to detecting." These expressions may be interpreted to have the same meaning, depending on the context.

[0029] First, the configuration and operation of multiple network elements common to multiple embodiments will be described. Fig. 1 shows an example configuration of a wireless communication system related to multiple embodiments. Each element (network function) shown in Fig. 1 can be implemented, for example, as a network element on dedicated hardware, as a software instance running on dedicated hardware, or as a virtualized function instantiated on an application platform.

[0030] In the example of FIG. 1 , the wireless communication system includes multiple UEs 1 and a Radio Access Network (RAN) node 2. Hereinafter, when describing matters common to the multiple UEs 1, reference will be made to the UE 1 unless otherwise specified. The UE 1 may be referred to by other terms, such as a wireless terminal, a mobile terminal, a mobile station, or a wireless transmit receive unit (WTRU). The RAN node 2 may be referred to by other terms, such as a network, a base station, or a radio station. If the system of FIG. 1 is an LTE system, the RAN node 2 may be an eNB. The UE 1 has at least one radio transceiver and communicates with the RAN node 2. The RAN node 2 manages, operates, or provides a cell 21 and communicates with the multiple UEs 1 within the cell 21 using cellular communication technology (e.g., E-UTRA Radio Access Technology).

[0031] The RAN node 2 may provide multiple cells including cell 21, and the UE 1 may be simultaneously connected to multiple cells provided by the RAN node 2. In other words, the UE 1 may perform carrier aggregation (CA) between multiple cells provided by the RAN node 2. In addition, the UE 1 may be simultaneously connected to the RAN node 2 and other RAN nodes for dual connectivity (DC).

[0032] The RAN node 2 may include a Base Band Unit (BBU) and one or more Remote Radio Heads (RRHs). The RRHs may also be referred to as Radio Units (RUs) or Transmission Reception Points (TRPs). The BBU may also include a Central Unit (CU) and one or more Distributed Units (DUs). Depending on the functional division between the BBU and the RRHs, in some implementations, the BBU may be the node that hosts the eNB's Radio Resource Control (RRC), Packet Data Convergence Protocol (PDCP), Radio Link Control (RLC), Medium Access Control (MAC), and upper physical (PHY) layers. In other implementations, the BBU may perform all digital signal processing, including lower PHY layer signal processing, and digital-to-analog (DA) and analog-to-digital (AD) conversion. Each RRH includes RF components coupled to one or more antennas and may include lower PHY layer signal processing circuits depending on the functional division between the BBU and the RRHs. The RF components include at least an amplifier and a frequency converter.

[0033] The RAN node 2 is connected to a RAN controller 3. The RAN controller 3 may be referred to as a control device or a control system. The RAN controller 3 may be integrated into the RAN node 2 (e.g., eNB). Alternatively, the RAN controller 3 may include one or both of a Non-RT RIC and a Near-RT RIC as defined in the O-RAN Alliance technical specifications. In this case, the RAN node 2 may be connected to the RAN controller 3 via one or both of an O1 interface and an E2 interface. According to the O-RAN architecture, the RAN node 2 may be referred to as an E2 node. Alternatively, the RAN controller 3 may be an Operations, Administration, and Maintenance (OAM) server or other controller. In other words, the functions of the RAN controller 3 may be located in the RAN node 2, a Non-RT RIC, a Near-RT RIC, an OAM server, or another controller, or may be distributed across any combination thereof.

[0034] First Embodiment A configuration example of a wireless communication system according to this embodiment is similar to the configuration example described with reference to FIG. 1 . FIG. 2 shows an example of the operation of the RAN controller 3. In step 201, the RAN controller 3 selects one of multiple downlink (DL) DTX patterns. Here, the multiple DL DTX patterns differ from one another in the number of subframes in which DL transmission by the RAN node 2 is suspended within one radio frame. In step 201, the RAN controller 3 applies the selected DL DTX pattern to the RAN node 2. In other words, the RAN node 2 selectively uses one of the multiple DL DTX patterns. Depending on some condition, for example, but not limited to, depending on the state of power supply to the RAN node 2, the RAN node 2 may selectively use one of the multiple DL DTX patterns. Additionally or alternatively, the RAN node 2 may selectively use one of the multiple DL DTX patterns depending on the number of UEs 1 active (or in the RRC_CONNECTED state) in the cell 21. Additionally or alternatively, the RAN node 2 may selectively use one of the multiple DL DTX patterns depending on a time period. Additionally or alternatively, the RAN node 2 may selectively use DL DTX patterns depending on the location of the RAN node 2 or cell 21.

[0035] The operation of the RAN controller 3 described with reference to FIG. 2 enables the RAN node 2 to use one selected from a number of DL DTX patterns, each of which differs in the number of subframes in a radio frame during which DL transmission by the RAN node 2 is suspended.

[0036] 3 illustrates an example of the operation of the UE 1, the RAN node 2, and the RAN controller 3. In step 301, the RAN controller 3 sends an indication, instruction, or request to the RAN node 2 to activate a power saving mode. The indication, instruction, or request may indicate a change from one power saving mode to another. The indication, instruction, or request indicates a selected one of multiple DL DTX patterns. The RAN node 2 applies the DL DTX pattern indicated by the RAN controller 3 to the cell 21.

[0037] In step 302, the RAN node 2 transmits configuration information indicating a selected one of a plurality of DL DTX patterns to the UE 1. The configuration information may be referred to as a subframe allocation configuration. The RAN node 2 may broadcast the configuration information in the cell 21. More specifically, the RAN node 2 may broadcast the configuration information in the cell 21 via cell-specific (or cell-wide) RRC signaling. The cell-specific (or cell-wide) RRC signaling may be system information, specifically a Master Information Block (MIB) or a SIB. The configuration information (e.g., MBSFN configuration) may be broadcast in SIB Type 2 (SIB2). Additionally or alternatively, the RAN node 2 may signal the configuration information in UE-specific RRC signaling. Additionally or alternatively, the RAN node 2 may signal the configuration information in Layer 2 or Layer 1 control information (e.g., Downlink Control Information (DCI)). The UE 1 receives downlink transmissions from the RAN node 2 based on the received configuration information. Specifically, the UE 1 may receive the downlink transmission of the RAN node 2 according to the DL DTX pattern indicated by the configuration information.

[0038] The operations of the UE 1, the RAN node 2, and the RAN controller 3 described with reference to Figure 3 enable the RAN node 2 to use one selected from a plurality of DL DTX patterns, each of which differs in the number of subframes in a radio frame during which DL transmission by the RAN node 2 is suspended, and this enables the UE 1 to receive DL transmission according to the DL DTX pattern.

[0039] Note that the operation shown in FIG. 3 is merely an example and may be modified as appropriate. In particular, step 302 may be omitted. In other words, the RAN node 2 may not transmit configuration information indicating a selected one of multiple DL DTX patterns to the UE 1. This contributes to reducing the power consumption of the RAN node 2 without adding any new functionality to the UE 1. The UE 1 may perform normal reception operations regardless of whether cell DTX is performed in the cell 21. In one example, as described below, each DL DTX pattern may be associated with the number and arrangement of MBSFN subframes within a radio frame. In this case, the RAN node 2 may transmit a normal MBSFN configuration corresponding to the selected DL DTX pattern to the UE 1. The normal MBSFN configuration is used by the UE 1 to know the arrangement of MBSFN subframes, but it is not necessary to indicate that DL DTX is performed in any MBSFN subframes (and unicast subframes).

[0040] In an LTE system, one radio frame consists of 10 subframes and may include multiple unicast subframes and one or more multicast / broadcast subframes. The multicast / broadcast subframes are MBSFN subframes. In one implementation, the RAN node 2 performs cell DTX operation by stopping DL transmission in one or more multicast / broadcast subframes within the radio frame, i.e., one or more MBSFN subframes. The RAN node 2 stops transmitting CRS and other physical signals and channels in the MBSFN subframes. The UE 1 stops downlink reception of CRS and other physical signals and channels from the RAN node 2 in the MBSFN subframes. The MBSFN subframes in which DL transmission is stopped may be referred to as blank subframes or DTX subframes.

[0041] FIG. 4 shows examples of multiple DL DTX patterns. In the example of FIG. 4, the RAN node 2 selectively uses one of five DL DTX patterns A to E. The DL DTX patterns A to E differ from each other in the number of MBSFN subframes (in which DL transmission is suspended) within a radio frame. That is, in the example of FIG. 4, the RAN node 2 (and the RAN controller 3) switches among the five DL DTX patterns by changing the ratio of unicast subframes to MBSFN subframes within a radio frame. Patterns A, B, C, D, and E have two, three, four, five, and six MBSFN subframes within a radio frame, respectively, and DL transmission is suspended in the MBSFN subframes. Therefore, the DL DTX patterns E, D, C, B, and A have the highest energy-saving effect in this order.

[0042] For example, depending on the state of power supply to the RAN node 2, the RAN node 2 may selectively use one of DL DTX patterns A to E. If the RAN node 2 is connected to an external power source and is powered by the external power source, the RAN node 2 may not use MBSFN subframes, and all subframes in a radio frame may be unicast subframes. On the other hand, if the RAN node 2 (or some of its components) is not powered by an external power source and is operating on an emergency battery, the RAN node 2 may use any of DL DTX patterns A to E. As the remaining power of the emergency battery decreases, the RAN node 2 may use a DL DTX pattern with a higher energy-saving effect.

[0043] In another example, the RAN node 2 may selectively use one of the DL DTX patterns A to E depending on the number of UEs 1 active (or in RRC_CONNECTED state) in the cell 21. As the number of UEs 1 active in the cell 21 decreases, the RAN node 2 may use a more energy-efficient DL DTX pattern.

[0044] 4 shows switching between five DL DTX patterns, but this is just an example. The RAN node 2, or the RAN node 2 and UE 1, may selectively use fewer than five DL DTX patterns or more than five DL DTX patterns. In a given DL DTX pattern, there may be only one MBSFN subframe (where DL transmission is suspended) in one radio frame, or there may be seven or more MBSFN subframes (where DL transmission is suspended) in one radio frame.

[0045] Additionally or alternatively, in some implementations, to further enhance energy savings, the RAN node 2 may stop DL transmissions in at least one of multiple unicast subframes within a radio frame. In some implementations, the RAN node 2 may switch between at least two of multiple DL DTX patterns by changing the number of unicast subframes within a radio frame in which DL transmissions by the RAN node 2 are stopped.

[0046] Specifically, the RAN node 2 (and the RAN controller 3) may stop DL transmissions in one or more multicast / broadcast subframes (e.g., MBSFN subframes) within a radio frame, and may also stop DL transmissions in at least one of multiple unicast subframes within that radio frame.

[0047] In other words, the multiple DL DTX patterns may include a first pattern in which downlink transmissions are stopped in multicast / broadcast subframes (e.g., MBSFN subframes) and a second pattern in which downlink transmissions are stopped in unicast subframes. In the first pattern, downlink transmissions are stopped in one or more multicast / broadcast subframes (e.g., MBSFN subframes) within a radio frame. In the second pattern, downlink transmissions are stopped in one or more unicast subframes within the radio frame in addition to one or more multicast / broadcast subframes. Additionally or additionally, downlink transmissions may be stopped in one or more unicast subframes within the radio frame.

[0048] Similarly, UE 1 may stop DL reception in at least one of multiple unicast subframes within a radio frame. However, as described above, UE 1 may perform normal reception operation regardless of whether cell DTX is occurring in cell 21. Specifically, UE 1 may attempt to receive physical signals and channels, such as PDCCH reception, in a unicast subframe regardless of whether DL transmission is stopped in that unicast subframe.

[0049] Figures 5 and 6 show examples of DL transmission suspension in unicast subframes. RAN node 2 may perform the DL transmission suspension shown in either Figure 5 or 6, or may perform the DL transmission suspension shown in both Figures 5 and 6. Similarly, UE 1 may stop receiving DL transmissions shown in either Figure 5 or 6, or may stop receiving DL transmissions shown in both Figures 5 and 6.

[0050] In the example of FIG. 5 , among the ten subframes (subframes #0 to #9) in a radio frame, DL transmission is stopped in one or both of the fifth subframe (i.e., subframe #4) and the tenth subframe (i.e., subframe #9). Subframes #4 and #9 are unicast subframes in which neither PSS nor SSS is transmitted. Typically, CRS is always transmitted in multiple resource elements in the first and fifth OFDM symbols of the first and second slots, respectively, in subframes #4 and #9. In addition, PDCCH and Physical Downlink Shared Channel (PDSCH) can be transmitted in subframes #4 and #9. In one or more DL DTX patterns, the RAN node 2 may stop transmitting CRS and other physical signals and channels (e.g., PDCCH and PDSCH) in unicast subframes #4 and #9.

[0051] In the example of FIG. 6 , among the ten subframes (subframes #0 to #9) in a radio frame, DL transmission is stopped in one or both of the first subframe (i.e., subframe #0) and the sixth subframe (i.e., subframe #5). Subframes #0 and #5 are unicast subframes in which the PSS and SSS are transmitted and the Physical Broadcast Channel (PBCH) carrying the MIB is transmitted. Typically, in subframes #0 and #5, the CRS is always transmitted in multiple resource elements in the first and fifth OFDM symbols of each of the first and second slots. Additionally, typically, in subframes #0 and #5, the PSS is always transmitted in the seventh OFDM symbol of the first slot, and the SSS is always transmitted in the sixth OFDM symbol of the first slot. Furthermore, typically, in subframes #0 and #5, the PBCH is always transmitted in the first to fourth OFDM symbols of the second slot. Furthermore, typically, in subframe #5, the PDSCH carrying the SIB1 is transmitted every other radio frame. In subframes #0 and #5, PDCCH and PDSCH can be transmitted.

[0052] In one or more DL DTX patterns, the RAN node 2 may stop transmitting CRS and other physical signals and channels (e.g., PSS, SSS, PBCH, PDCCH, and PDSCH) in one or both of the unicast subframes #0 and #5. Note that PSS, SSS, MIB (PBCH), and SIB1 transmissions are necessary for the UE 1 to synchronize to and access the cell 21. Therefore, the RAN node 2 may stop PSS, SSS, MIB (PBCH), and SIB1 transmissions in some radio frames by lengthening the period or cycle of PSS, SSS, MIB (PBCH), and SIB1 transmissions beyond their normal reference values.

[0053] Second Embodiment A configuration example of a wireless communication system according to this embodiment is similar to the configuration example described with reference to Fig. 1 . Fig. 7 shows an example of the operation of the RAN controller 3. In step 701, the RAN controller 3 monitors the state of power supply to the RAN node 2. The RAN controller 3 may monitor the state of power supply to some components of the RAN node 2 (e.g., BBU, CU, DU, or RRH). In step 702, the RAN controller 3 selects one of multiple downlink DTX patterns to be applied to the RAN node 2, depending on the state of power supply to the RAN node 2 (or some of its components). Specific examples of the multiple downlink DTX patterns may be similar to those described in the first embodiment. The operation of the RAN controller 3 described with reference to Fig. 7 enables the RAN node 2 to selectively use multiple downlink DTX patterns depending on the state of power supply to the RAN node 2.

[0054] Figure 8 shows an example of changing the DL DTX pattern depending on the state of power supply to the RAN node 2. In the example of Figure 8, the RAN node 2 switches its power saving mode between four modes, specifically no restriction mode 801, restricted unicast mode 802, restricted mobility mode 803, and emergency mode 804. As will be described below, three of the four power saving modes, modes 802 to 804, are associated with different DL DTX patterns.

[0055] When the RAN node 2 (or some of its components) is connected to an external power source and receives power from the external power source, the RAN controller 3 applies the unrestricted mode 801 to the RAN node 2. In the unrestricted mode 801, the ratio of unicast subframes to MBSFN subframes in a radio frame is 10:0. That is, in the unrestricted mode 801, all 10 subframes in a radio frame are unicast subframes, and cell DTX operation for energy saving is not performed. Also, in the unrestricted mode 801, the transmission cycles or periods of the PSS, SSS, MIB, and SIB1 remain normal and are not changed.

[0056] If the RAN node 2 (or some of its components) is not powered by an external power source and is running on an emergency battery, the RAN controller 3 applies restricted unicast mode 802, restricted mobility mode 803, or emergency mode 804 to the RAN node 2. The RAN controller 3 selects one of the restricted unicast mode 802, restricted mobility mode 803, and emergency mode 804 depending on the remaining capacity of the emergency battery. In one example, if the remaining battery capacity is 50% or more, the RAN controller 3 may select the restricted unicast mode 802. If the remaining battery capacity is below 50%, the RAN controller 3 may select the restricted mobility mode 803. If the remaining battery capacity further decreases and is close to running out (e.g., if the remaining battery capacity is less than 10%), the RAN controller 3 may select the emergency mode 804.

[0057] In restricted unicast mode 802, for example, the ratio of unicast subframes to MBSFN subframes in a radio frame is 6:4. RAN node 2 performs cell DTX operation by stopping DL transmission in four MBSFN subframes in a radio frame. In restricted unicast mode 802, the transmission cycle or period of PSS, SSS, MIB, and SIB1 remains normal and unchanged. Therefore, RAN node 2 continues DL transmission in all unicast subframes.

[0058] In restricted mobility mode 803, the number of MBSFN subframes in a radio frame is greater than that in restricted unicast mode 802. In other words, in restricted mobility mode 803, the number of unicast subframes in a radio frame is smaller than that in restricted unicast mode 802. For example, in restricted mobility mode 803, the ratio of unicast subframes to MBSFN subframes in a radio frame is 4:6. RAN node 2 performs cell DTX operation by suspending DL transmission in six MBSFN subframes in a radio frame. In addition, in restricted mobility mode 803, RAN node 2 extends the transmission cycle of PSS, SSS, MIB, and SIB1 by twice the normal cycle. The RAN node 2 also suspends DL transmission in unicast subframes in which none of PSS, SSS, MIB, and SIB1 is transmitted.

[0059] In the emergency mode 804, the number of MBSFN subframes in a radio frame is greater than that in the restricted unicast mode 802. In other words, in the emergency mode 804, the number of unicast subframes in a radio frame is less than that in the restricted unicast mode 802. For example, in the emergency mode 804, the ratio of unicast subframes to MBSFN subframes in a radio frame is 4:6, similar to that in the restricted mobility mode 803. The RAN node 2 performs cell DTX operation by suspending DL transmission in six MBSFN subframes in a radio frame. In addition, in the restricted mobility mode 804, the RAN node 2 extends the transmission cycle of the PSS, SSS, MIB, and SIB1 by four times compared to normal. The RAN node 2 also suspends DL transmission in unicast subframes in which none of the PSS, SSS, MIB, and SIB1 is transmitted.

[0060] The ratio of unicast subframes to MBSFN subframes in a radio frame in each mode shown in Fig. 8 is merely an example. Similarly, the transmission periods of PSS, SSS, MIB, and SIB1 in each mode shown in Fig. 8 are also merely an example. These may be defined so that the number of subframes in which DL transmission is performed in one radio frame decreases in the order of modes 801, 802, 803, and 804.

[0061] It should also be understood that the names of the four power saving modes 801-804 shown in Figure 8 are merely exemplary. These four power saving modes 801-804 may be referred to by other names, such as first, second, third, and fourth power modes. The power saving mode 801 may also be referred to as a normal mode or a non-power saving mode. The RAN node 2 may use fewer or more than four power saving modes.

[0062] 9 shows an example of signaling for activating, deactivating, or changing a power saving mode. In step 901, the RAN controller 3 receives a power supply status report from the battery controller 7. The battery controller 7 manages the power supply to the RAN node 2 (or some of its components). The power supply status report indicates the status of the power supply to the RAN node 2 (or some of its components). The power supply status report may indicate whether the RAN node 2 is powered by an external power source. Additionally or alternatively, the power supply status report may indicate the remaining capacity of a battery supplying power to the RAN node 2. Additionally or alternatively, the power supply status report may indicate whether any failure has occurred in the power supply to the RAN node 2. In one example, the power supply status report may indicate any of the power supply statuses described with reference to FIG. 8.

[0063] In step 902, the RAN controller 3 sends an indication, instruction, or request to activate, deactivate, or change the power saving mode to the RAN node 2. More specifically, in the example of Figure 9, the RAN controller 3 sends the indication, instruction, or request to the BBU 23 of the RAN node 2. The RAN controller 3 may decide to activate, deactivate, or change the power saving mode based on the power supply status report.

[0064] In step 903, the BBU 23 of the RAN node 2 instructs the RU 25 to update (activate, deactivate, or change) the power saving mode. The BBU 23 may provide the RU 25 with a subframe allocation setting corresponding to the applied power saving mode or DL ​​DTX pattern.

[0065] In step 904, the BBU 23 of the RAN node 2 transmits a subframe allocation configuration corresponding to the applied power saving mode or DL ​​DTX pattern to the UE 1. The RAN node 2 may broadcast the configuration in the cell 21 via cell-specific (or cell-wide) RRC signaling. The configuration may be an MBSFN configuration, and the RAN node 2 may broadcast the configuration in the SIB2. Additionally or alternatively, the RAN node 2 may notify the configuration information via UE-specific RRC signaling. Additionally or alternatively, the RAN node 2 may notify the configuration information via Layer 2 or Layer 1 control information (e.g., DCI). The UE 1 receives downlink transmissions from the RAN node 2 based on the received subframe allocation configuration. Specifically, the UE 1 receives downlink transmissions from the RAN node 2 in accordance with the DL DTX pattern indicated by the subframe allocation configuration.

[0066] Note that the operation shown in FIG. 9 is merely an example and may be modified as appropriate. In particular, step 904 may be omitted. In other words, the RAN node 2 may not transmit to the UE 1 a subframe allocation configuration corresponding to the applied power saving mode or DL ​​DTX pattern. This contributes to reducing the power consumption of the RAN node 2 without adding new functionality to the UE 1. The UE 1 may perform normal reception operations regardless of whether cell DTX is performed in the cell 21. In one example, the RAN node 2 may transmit to the UE 1 a normal MBSFN configuration corresponding to the selected DL DTX pattern. The normal MBSFN configuration is used by the UE 1 to know the arrangement of MBSFN subframes, but it is not necessary to indicate that DL DTX is performed in any MBSFN subframes (and unicast subframes).

[0067] Next, exemplary configurations of the UE 1, RAN node 2, and RAN controller 3 according to the above-described embodiments will be described. FIG. 10 is a block diagram showing an exemplary configuration of the UE 1. The RF transceiver 1001 performs analog RF signal processing for communication with the RAN node 2. The RF transceiver 1001 may include multiple transceivers. The analog RF signal processing performed by the RF transceiver 1001 includes frequency up-conversion, frequency down-conversion, and amplification. The RF transceiver 1001 is coupled to the antenna array 1002 and the baseband processor 1003. The RF transceiver 1001 receives modulation symbol data (or OFDM symbol data) from the baseband processor 1003, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 1002. The RF transceiver 1001 also generates a baseband receive signal based on the receive RF signal received by the antenna array 1002 and provides the baseband receive signal to the baseband processor 1003. The RF transceiver 1001 may include an analog beamformer circuit for beamforming, which may include, for example, multiple phase shifters and multiple power amplifiers.

[0068] The baseband processor 1003 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communications. Digital baseband signal processing includes (a) data compression / decompression, (b) data segmentation / concatenation, (c) transmission format (transmission frame) generation / decomposition, (d) transmission path coding / decoding, (e) modulation (symbol mapping) / demodulation, and (f) generation of OFDM symbol data (baseband OFDM signal) using Inverse Fast Fourier Transform (IFFT). Meanwhile, control plane processing includes communication management for Layer 1 (e.g., transmit power control), Layer 2 (e.g., radio resource management and hybrid automatic repeat request (HARQ) processing), and Layer 3 (e.g., signaling related to attachment, mobility, and call management).

[0069] For example, the digital baseband signal processing by the baseband processor 1003 may include signal processing of a PDCP layer, an RLC layer, a MAC layer, and a PH layer. Also, the control plane processing by the baseband processor 1003 may include processing of a Non-Access Stratum (NAS) protocol, an RRC protocol, MAC Control Elements (CEs), and Downlink Control Information (DCIs).

[0070] The baseband processor 1003 may perform MIMO encoding and precoding for beamforming.

[0071] The baseband processor 1003 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a Central Processing Unit (CPU) or a Micro Processing Unit (MPU)) that performs control plane processing. In this case, the protocol stack processor that performs control plane processing may be shared with the application processor 1004, which will be described later.

[0072] The application processor 1004 is also referred to as a CPU, MPU, microprocessor, or processor core. The application processor 1004 may include multiple processors (multiple processor cores). The application processor 1004 executes a system software program (operating system (OS)) and various application programs (e.g., a calling application, a web browser, a mailer, a camera operation application, and a music playback application) read from the memory 1006 or other memories, thereby realizing various functions of the UE 1.

[0073] In some implementations, the baseband processor 1003 and the application processor 1004 may be integrated on a single chip, as indicated by the dashed line (1005) in Figure 10. In other words, the baseband processor 1003 and the application processor 1004 may be implemented as a single System on Chip (SoC) device 1005. An SoC device may also be called a system Large Scale Integration (LSI) or chipset.

[0074] The memory 1006 is volatile memory, nonvolatile memory, or a combination thereof. The memory 1006 may include multiple physically independent memory devices. The volatile memory may be, for example, static random access memory (SRAM), dynamic RAM (DRAM), or a combination thereof. The nonvolatile memory may be mask read only memory (MROM), electrically erasable programmable ROM (EEPROM), flash memory, a hard disk drive, or any combination thereof. For example, the memory 1006 may include an external memory device accessible from the baseband processor 1003, the application processor 1004, and the SoC 1005. The memory 1006 may also include an internal memory device integrated within the baseband processor 1003, the application processor 1004, or the SoC 1005. Furthermore, the memory 1006 may include memory within a Universal Integrated Circuit Card (UICC).

[0075] The memory 1006 may store one or more software modules (computer programs) 1007 containing instructions and data for processing by the UE 1. In some implementations, the baseband processor 1003 or the application processor 1004 may be configured to read and execute the software modules 1007 from the memory 1006 to perform the processing of the UE 1 described in one or more of the embodiments.

[0076] It should be noted that the control plane processing and operations performed by UE 1 described in the above embodiment can be realized by elements other than RF transceiver 1001 and antenna array 1002, namely, at least one of baseband processor 1003 and application processor 1004, and memory 1006 storing software modules 1007.

[0077] FIG. 11 is a block diagram showing an example configuration of a RAN node 2. Referring to FIG. 11, the RAN node 2 includes an RF transceiver 1101, a network interface 1103, a processor 1104, and a memory 1105. The RF transceiver 1101 performs analog RF signal processing for communication with UEs 1. The RF transceiver 1101 may include multiple transceivers. The RF transceiver 1101 is coupled to an antenna array 1102 and a processor 1104. The RF transceiver 1101 receives modulation symbol data from the processor 1104, generates a transmit RF signal, and provides the transmit RF signal to the antenna array 1102. The RF transceiver 1101 also generates a baseband receive signal based on the receive RF signal received by the antenna array 1102 and provides the baseband receive signal to the processor 1104. The RF transceiver 1101 may include an analog beamformer circuit for beamforming. The analog beamformer circuit may include, for example, multiple phase shifters and multiple power amplifiers.

[0078] The network interface 1103 is used to communicate with network nodes (e.g., other RAN nodes, and control and forwarding nodes of the core network), and may include, for example, a network interface card (NIC) compliant with the IEEE 802.3 series.

[0079] The processor 1104 performs digital baseband signal processing (data plane processing) and control plane processing for wireless communication. The processor 1104 may include multiple processors. For example, the processor 1104 may include a modem processor (e.g., a Digital Signal Processor (DSP)) that performs digital baseband signal processing and a protocol stack processor (e.g., a CPU or MPU) that performs control plane processing. The processor 1104 may include a digital beamformer module for beamforming. The digital beamformer module may include a MIMO encoder and a precoder.

[0080] The memory 1105 is configured by a combination of volatile memory and non-volatile memory. The volatile memory is, for example, SRAM or DRAM, or a combination thereof. The non-volatile memory is, for example, MROM, EEPROM, flash memory, or a hard disk drive, or any combination thereof. The memory 1105 may include storage located remotely from the processor 1104. In this case, the processor 1104 may access the memory 1105 via the network interface 1103 or other I / O interface.

[0081] The memory 1105 may store one or more software modules (computer programs) 1106 containing instructions and data for processing by the RAN node 2. In some implementations, the processor 1104 may be configured to read and execute the software modules 1106 from the memory 1105 to perform the processing of the RAN node 2 described in one or more of the embodiments.

[0082] Figure 12 is a block diagram showing an example configuration of the RAN controller 3. In the example of Figure 12, the RAN controller 3 is implemented as a computer system. The computer system includes one or more processors 1210, memory 1220, and mass storage 1230, which communicate with each other via a bus 1270. The one or more processors 1210 may include, for example, a CPU or a graphics processing unit (GPU), or both. The computer system may also include other devices such as one or more output devices 1240, one or more input devices 1250, and one or more peripherals 1260. The one or more peripherals 1260 may include a modem, a network adapter, or any combination thereof.

[0083] One or both of the memory 1220 and the mass storage 1230 may include a computer-readable medium having stored thereon one or more sets of instructions, which may be located partially or completely in memory within the one or more processors 1210. These instructions, when executed in the one or more processors 1210, cause the one or more processors 1210 to provide the functionality of the RAN controller 3 described in the above embodiments.

[0084] As described with reference to Figures 10, 11, and 12, each of the processors included in the UE 1, the RAN node 2, and the RAN controller 3 according to the above-described embodiments can execute one or more programs including instructions for causing a computer to perform the algorithms described with reference to the drawings. The programs include instructions (or software code) that, when loaded into a computer, cause the computer to perform one or more functions described in the embodiments. The programs may be stored on a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technology, CD-ROM, digital versatile disk (DVD), Blu-ray disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage device. The programs may also be transmitted on a transitory computer-readable medium or communication medium. By way of example and not limitation, transitory computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals.

[0085] The above-described embodiments are merely examples of application of the technical ideas obtained by the inventors of the present invention. In other words, the technical ideas are not limited to the above-described embodiments, and various modifications are possible.

[0086] For example, some or all of the above embodiments may also be described as, but are not limited to, the following appendices. Some or all of the elements (e.g., configurations and functions) described in appendices directed to devices (e.g., control devices) may naturally also be described as appendices directed to methods and programs. For example, some or all of the elements described in appendices 2-15, which are dependent on appendices 1, may also be described as appendices dependent on appendices 28 and 31, due to the same dependency relationship as appendices 2-15. Similarly, some or all of the elements described in appendices 18-27, which are dependent on appendices 17, may also be described as appendices dependent on appendices 30 and 33, due to the same dependency relationship as appendices 18-27. Some or all of the elements described in any appendice may be applicable to various hardware, software, recording means for recording software, systems, and methods.

[0087] (Supplementary Note 1) A control device comprising means for selectively applying one of a plurality of downlink discontinuous transmission (DTX) patterns to a radio access network node, wherein the plurality of downlink DTX patterns differ from one another in the number of subframes in a radio frame in which downlink transmission by the radio access network node is stopped. (Supplementary Note 2) The control device according to Supplementary Note 1, wherein the radio frame consists of a plurality of unicast subframes and one or more multicast / broadcast subframes. (Supplementary Note 3) The control device according to Supplementary Note 2, wherein the plurality of downlink DTX patterns include a first pattern in which downlink transmission is stopped in the one or more multicast / broadcast subframes, and a second pattern in which downlink transmission is stopped in one or more unicast subframes in addition to the one or more multicast / broadcast subframes. (Supplementary Note 4) The control device according to Supplementary Note 2 or 3, wherein at least one of the plurality of downlink DTX patterns causes the radio access network node to stop transmission of Cell-specific Reference Signals (CRS) and other physical signals and channels in at least one of the one or more multicast / broadcast subframes. (Supplementary Note 5) The control device according to any one of Supplements 2 to 4, wherein at least one of the plurality of downlink DTX patterns causes the radio access network node to stop downlink transmission in at least one of the plurality of unicast subframes in addition to stopping downlink transmission in the one or more multicast / broadcast subframes. (Supplementary Note 6) The control device according to any one of Supplements 2 to 5, wherein the applying means is configured to switch between at least two of the plurality of downlink DTX patterns by changing a ratio of unicast subframes and multicast / broadcast subframes within the radio frame.(Supplementary Note 7) The control device according to any one of Supplementary Notes 2 to 6, wherein the applying means is configured to switch between at least two of the plurality of downlink DTX patterns by changing a number of unicast subframes in which downlink transmission by the radio access network node is stopped within the radio frame. (Supplementary Note 8) The control device according to any one of Supplementary Notes 2 to 7, wherein at least one of the plurality of downlink DTX patterns causes the radio access network node to stop downlink transmission in remaining unicast subframes of the plurality of unicast subframes except for a plurality of specific unicast subframes in which a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS) are transmitted. (Supplementary Note 9) The control device according to any one of Supplements 2 to 8, wherein at least one of the plurality of downlink DTX patterns causes the radio access network node to stop downlink transmission in at least one specific unicast subframe in which a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS) are transmitted. (Supplementary Note 10) The control device according to Supplementary Note 9, wherein at least one of the plurality of downlink DTX patterns causes the radio access network node to stop downlink transmission in the at least one specific unicast subframe by making a transmission period of the PSS and the SSS longer than a reference value. (Supplementary Note 11) The control device according to any one of Supplements 2 to 10, wherein the radio frame is a Long Term Evolution (LTE) radio frame, and wherein each of the one or more multicast / broadcast subframes is a Multimedia Broadcast / Multicast Service (MBMS) over a Single Frequency Network (MBSFN) subframe.(Supplementary Note 12) The control device according to any one of Supplements 1 to 11, further comprising: means for selecting one of the plurality of downlink DTX patterns to be applied to the radio access network node depending on a state of power supply to the radio access network node. (Supplementary Note 13) The control device according to any one of Supplements 1 to 12, wherein the control device is arranged in the radio access network node. (Supplementary Note 14) The control device according to any one of Supplements 1 to 12, wherein the control device is arranged in an Open Radio Access Network (O-RAN) Non-Real-Time (Non-RT) RIC or an O-RAN Near-Real-Time (Near-RT) RIC. (Supplementary Note 15) The control device according to any one of Supplements 1 to 12, wherein the control device is arranged in an Operations, Administration and Maintenance (OAM) server or other controller coupled to the radio access network node. (Supplementary Note 16) A radio access network node comprising the control device according to any one of Supplements 1 to 12. (Supplementary Note 17) A wireless terminal comprising: means for receiving, from a radio access network node, configuration information indicating a selected one of a plurality of downlink discontinuous transmission (DTX) patterns; and means for receiving downlink transmissions of the radio access network node based on the configuration information, wherein the plurality of downlink DTX patterns differ from each other in the number of subframes in a radio frame during which downlink transmissions by the radio access network node are suspended. (Supplementary Note 18) The wireless terminal according to Supplementary Note 17, wherein the radio frame consists of a plurality of unicast subframes and one or more multicast / broadcast subframes.(Supplementary Note 19) The wireless terminal according to Supplementary Note 18, wherein the plurality of downlink DTX patterns include a first pattern in which downlink transmission in the one or more multicast / broadcast subframes is stopped, and a second pattern in which downlink transmission in one or more unicast subframes in addition to the one or more multicast / broadcast subframes is stopped. (Supplementary Note 20) The wireless terminal according to Supplementary Note 18 or 19, wherein at least one of the plurality of downlink DTX patterns causes the wireless terminal to stop downlink reception of Cell-specific Reference Signals (CRS) and other physical signals and channels from the radio access network node in at least one of the one or more multicast / broadcast subframes. (Supplementary Note 21) The wireless terminal of any one of Supplements 18 to 20, wherein at least one of the plurality of downlink DTX patterns causes the wireless terminal to stop downlink reception from the radio access network node in at least one of the plurality of unicast subframes in addition to stopping downlink reception from the radio access network node in the one or more multicast / broadcast subframes. (Supplementary Note 22) The wireless terminal of any one of Supplements 18 to 21, wherein switching between at least two of the plurality of downlink DTX patterns is performed by changing a ratio of unicast subframes to multicast / broadcast subframes within the radio frame. (Supplementary Note 23) The wireless terminal of any one of Supplements 18 to 22, wherein switching between at least two of the plurality of downlink DTX patterns is performed by changing a number of unicast subframes in which downlink transmission by the radio access network node is stopped within the radio frame.(Supplementary Note 24) The radio terminal according to any one of Supplementary Notes 18 to 23, wherein at least one of the plurality of downlink DTX patterns causes the radio terminal to stop downlink reception from the radio access network node in remaining unicast subframes of the plurality of unicast subframes except for a plurality of specific unicast subframes in which a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS) are transmitted. (Supplementary Note 25) The radio terminal according to any one of Supplementary Notes 18 to 24, wherein at least one of the plurality of downlink DTX patterns causes the radio terminal to stop downlink reception from the radio access network node in at least one specific unicast subframe in which a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS) are transmitted. (Supplementary Note 26) The wireless terminal according to Supplementary Note 25, wherein at least one of the plurality of downlink DTX patterns causes the wireless terminal to stop downlink reception from the radio access network node in the at least one specific unicast subframe by making a transmission period of the PSS and the SSS longer than a reference value. (Supplementary Note 27) The wireless terminal according to any one of Supplements 18 to 26, wherein the radio frame is a Long Term Evolution (LTE) radio frame, and each of the one or more multicast / broadcast subframes is a Multimedia Broadcast / Multicast Service (MBMS) over a Single Frequency Network (MBSFN) subframe.(Supplementary Note 28) A method performed by a control device, comprising selectively applying one of a plurality of downlink discontinuous transmission (DTX) patterns to a radio access network node, wherein the plurality of downlink DTX patterns differ from one another in the number of subframes in a radio frame in which downlink transmission by the radio access network node is suspended. (Supplementary Note 29) A method performed by a radio access network node, comprising selectively using one of a plurality of downlink discontinuous transmission (DTX) patterns, wherein the plurality of downlink DTX patterns differ from one another in the number of subframes in a radio frame in which downlink transmission by the radio access network node is suspended. (Supplementary Note 30) A method performed by a wireless terminal, comprising: receiving, from a radio access network node, configuration information indicating a selected one of a plurality of downlink discontinuous transmission (DTX) patterns, and receiving downlink transmission of the radio access network node based on the configuration information, wherein the plurality of downlink DTX patterns differ from one another in the number of subframes in a radio frame in which downlink transmission by the radio access network node is suspended. (Supplementary Note 31) A program causing a computer to perform a method for a control device, the method comprising selectively applying one of a plurality of downlink discontinuous transmission (DTX) patterns to a radio access network node, the plurality of downlink DTX patterns differing from one another in the number of subframes in a radio frame during which downlink transmission by the radio access network node is suspended.(Supplementary Note 32) A program causing a computer to perform a method for a radio access network node, the method comprising selectively using one of a plurality of downlink discontinuous transmission (DTX) patterns, the plurality of downlink DTX patterns differing from one another in a number of subframes within a radio frame during which downlink transmission by the radio access network node is suspended. (Supplementary Note 33) A program causing a computer to perform a method for a wireless terminal, the method comprising: receiving, from a radio access network node, configuration information indicating a selected one of a plurality of downlink discontinuous transmission (DTX) patterns, and receiving a downlink transmission of the radio access network node based on the configuration information, the plurality of downlink DTX patterns differing from one another in a number of subframes within a radio frame during which downlink transmission by the radio access network node is suspended.

[0088] This application claims priority based on Japanese Patent Application No. 2024-002890, filed January 11, 2024, the disclosure of which is incorporated herein in its entirety by reference.

[0089] REFERENCE SIGNS LIST 1 UE 2 RAN node 3 RAN controller 7 Battery controller 21 Cell 23 BBU 25 RU 1003 Baseband processor 1004 Application processor 1006 Memory 1007 Modules 1104 Processor 1105 Memory 1106 Modules 1210 Processor 1220 Memory 1230 Mass storage

Claims

1. A control device comprising means for selectively applying any one of a plurality of downlink discontinuous transmission (DTX) patterns to a radio access network node, wherein the plurality of downlink DTX patterns have different numbers of subframes in which downlink transmission by the radio access network node is stopped within a radio frame.

2. The control device according to claim 1, wherein the radio frame consists of a plurality of unicast subframes and one or more multicast / broadcast subframes.

3. The control device according to claim 2, wherein the plurality of downlink DTX patterns include a first pattern in which downlink transmission in the one or more multicast / broadcast subframes is stopped, and a second pattern in which downlink transmission is stopped in one or more unicast subframes in addition to the one or more multicast / broadcast subframes.

4. The control device according to claim 2 or 3, wherein at least one of the plurality of downlink DTX patterns causes the radio access network node to stop transmission of Cell-specific Reference Signals (CRS) and other physical signals and channels in at least one of the one or more multicast / broadcast subframes.

5. The control device according to any one of claims 2 to 4, wherein at least one of the plurality of downlink DTX patterns causes the radio access network node to stop downlink transmission not only in the one or more multicast / broadcast subframes but also in at least one of the plurality of unicast subframes.

6. The control device according to any one of claims 2 to 5, wherein the applying means is configured to switch between at least two of the plurality of downlink DTX patterns by changing the ratio of unicast subframes to multicast / broadcast subframes within the radio frame.

7. The applying means is configured to switch between at least two of the plurality of downlink DTX patterns by changing, within the radio frame, the number of unicast subframes in which downlink transmission by the radio access network node is stopped, the control device according to any one of claims 2 to 6.

8. At least one of the plurality of downlink DTX patterns causes the radio access network node to stop downlink transmission in the remaining unicast subframes of the plurality of unicast subframes, excluding a plurality of specific unicast subframes in which a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS) are transmitted, the control device according to any one of claims 2 to 7.

9. At least one of the plurality of downlink DTX patterns causes the radio access network node to stop downlink transmission in at least one specific unicast subframe in which a Primary Synchronization Signal (PSS) and a Secondary Synchronization Signal (SSS) are transmitted, the control device according to any one of claims 2 to 8.

10. At least one of the plurality of downlink DTX patterns causes the radio access network node to stop downlink transmission in the at least one specific unicast subframe by making the transmission period of the PSS and the SSS longer than a reference value, the control device according to claim 9.

11. The radio frame is a Long Term Evolution (LTE) radio frame, and each of the one or more multicast / broadcast subframes is a Multimedia Broadcast / Multicast Service (MBMS) over a Single Frequency Network (MBSFN) subframe, the control device according to any one of claims 2 to 10.

12. The control device according to any one of claims 1 to 11, further comprising means for selecting one of the plurality of downlink DTX patterns applied to the radio access network node according to the state of power supply to the radio access network node.

13. The control device according to any one of claims 1 to 12, wherein the control device is arranged in the radio access network node.

14. The control device according to any one of claims 1 to 12, wherein the control device is arranged in an Open Radio Access Network (O-RAN) Non-Real-Time (Non-RT) RIC or an O-RAN Near-Real-Time (Near-RT) RIC.

15. A wireless terminal comprising means for receiving, from a radio access network node, configuration information indicating a selected one of a plurality of downlink discontinuous transmission (DTX) patterns, and means for receiving downlink transmissions of the radio access network node based on the configuration information, wherein the plurality of downlink DTX patterns have different numbers of subframes in which downlink transmissions by the radio access network node are stopped within a radio frame.

16. A method performed by a control device, comprising selectively applying any one of a plurality of downlink discontinuous transmission (DTX) patterns, wherein the plurality of downlink DTX patterns have different numbers of subframes in which downlink transmissions by the radio access network node are stopped within a radio frame.

17. A method performed by a radio access network node, comprising selectively using any one of a plurality of downlink discontinuous transmission (DTX) patterns, wherein the plurality of downlink DTX patterns have different numbers of subframes in which downlink transmissions by the radio access network node are stopped within a radio frame. A program causing a computer to perform a method for a control device, the method comprising selectively applying one of a plurality of downlink discontinuous transmission (DTX) patterns to a radio access network node, wherein the plurality of downlink DTX patterns differ from each other in the number of subframes in which downlink transmission by the radio access network node is stopped within a radio frame. A program causing a computer to perform a method for a radio access network node, the method comprising selectively using one of a plurality of downlink discontinuous transmission (DTX) patterns, wherein the plurality of downlink DTX patterns differ from each other in the number of subframes in which downlink transmission by the radio access network node is stopped within a radio frame. A program causing a computer to perform a method for a wireless terminal, the method comprising receiving, from a radio access network node, configuration information indicating one selected from among a plurality of downlink discontinuous transmission (DTX) patterns, and receiving downlink transmission from the radio access network node based on the configuration information, wherein the plurality of downlink DTX patterns differ from each other in the number of subframes in which downlink transmission by the radio access network node is stopped within a radio frame.

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