WO2020108746A1

WO2020108746A1 - Network controlled measurement chain for enabling low energy consumption

Info

Publication number: WO2020108746A1
Application number: PCT/EP2018/082810
Authority: WO
Inventors: Klaus Ingemann Pedersen; Frank Frederiksen; Daniela Laselva; Mads LAURIDSEN
Original assignee: Nokia Technologies Oy
Priority date: 2018-11-28
Filing date: 2018-11-28
Publication date: 2020-06-04

Abstract

There is provided an apparatus, said apparatus comprising means for receiving, at a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode, determining, based on the information, a number of transceivers to use when operating in the second mode and causing the user equipment to operate in the second mode using the determined number of transceivers.

Description

Title

Network controlled measurement chain for enabling low energy consumption

Field

The present application relates to a method, apparatus, system and computer program and in particular but not exclusively to network controlled user equipment (UE) radio resource management (RRM) measurement chain/antenna configuration.

Background

A communication system can be seen as a facility that enables communication sessions between two or more entities such as user terminals, base stations and/or other nodes by providing carriers between the various entities involved in the communications path. A communication system can be provided for example by means of a communication network and one or more compatible communication devices (also referred to as station or user equipment) and/or application servers. The communication sessions may comprise, for example, communication of data for carrying communications such as voice, video, electronic mail (email), text message, multimedia, content data, time-sensitive network (TSN) flows and/or data in an industrial application such as critical system messages between an actuator and a controller, critical sensor data (such as measurements, video feed etc.) towards a control system and so on. Non-limiting examples of services provided comprise two-way or multi-way calls, data communication or multimedia services and access to a data network system, such as the Internet.

In a wireless communication system at least a part of a communication session, for example, between at least two stations or between at least one station and at least one application server (e.g. for video), occurs over a wireless link. Examples of wireless systems comprise public land mobile networks (PLMN) operating based on 3GPP radio standards such as E- UTRA, New Radio, satellite based communication systems and different wireless local networks, for example wireless local area networks (WLAN). The wireless systems can typically be divided into cells, and are therefore often referred to as cellular systems.

A user can access the communication system by means of an appropriate communication device or terminal. A communication device of a user may be referred to as user equipment (UE) or user device. A communication device is provided with an appropriate signal receiving and transmitting apparatus for enabling communications, for example enabling access to a communication network or communications directly with other users. The communication device may access one or more carriers provided by the network, for example a base station of a cell, and transmit and/or receive communications on the one or more carriers. In carrier aggregation (CA) two or more carriers are combined into one channel. In dual connectivity (DC), two carriers from different sites are combined, that is a user equipment may be dual (or multi) connected to two (or more) sites.

The communication system and associated devices typically operate in accordance with a given standard or specification which sets out what the various entities associated with the system are permitted to do and how that should be achieved. Communication protocols and/or parameters which shall be used for the connection are also typically defined. One example of a communications system is UTRAN (3G radio). Other examples of communication systems are the long-term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) based on the E-UTRAN radio-access technology, and so-called 5G system (5GS) including the 5G or next generation core (NGC) and the 5G Access network based on the New Radio (NR) radio-access technology. 5GS including NR are being standardized by the 3rd Generation Partnership Project (3GPP).

Summary

In a first aspect there is provided an apparatus, said apparatus comprising means for receiving, at a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode, determining, based on the information, a number of transceivers to use when operating in the second mode and causing the user equipment to operate in the second mode using the determined number of transceivers.

The information may comprise an indication of at least one of a first time period, a first mobility event and a first failure event.

The information may comprise an indication of radio conditions.

The first mode may comprise a radio resource control connected mode. The second mode may comprise one of a radio resource control idle mode and a radio resource control inactive mode. The apparatus may comprise means for providing to the network an indication of the number of active transmitters.

The indication of the number of transceivers to use when operating in the second mode may comprise an indication of a number of transceivers to use for a communication type.

The transceivers may comprise at least one of a receiver chain and a transmitter chain.

The information may comprise an indication of at least one of an absolute number of transceivers, a delta to a default configuration number of transceivers and an index to a predefined transceiver configuration.

In a second aspect there is provided an apparatus comprising means for providing, to a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode.

The apparatus may comprise means for determining, based on information associated with the user equipment, the number of transceivers the user equipment should use when operating in a second mode.

The information associated with the user equipment may comprise at least one of mobility information, interference information, network load and radio coverage information.

The information comprising an indication of a number of transceivers to use when operating in the second mode may comprise an indication of at least one of a first time period, a first mobility event and a first failure event.

The information comprising an indication of a number of transceivers to use when operating in the second mode may comprise an indication of radio conditions.

The first mode may comprise a radio resource control connected mode. The second mode may comprise one of a radio resource control idle mode and a radio resource control inactive mode.

The apparatus may comprise means for receiving from the UE an indication of the number of active transmitters. The indication of the number of transceivers to use when operating in the second mode may comprise an indication of a number of transceivers to use for a communication type.

The information comprising an indication of a number of transceivers to use when operating in the second mode may comprise an indication of at least one of an absolute number of transceivers, a delta to a default configuration number of transceivers and an index to a predefined transceiver configuration.

In a third aspect there is provided a method comprising receiving, at a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode, determining, based on the information, a number of transceivers to use when operating in the second mode and causing the user equipment to operate in the second mode using the determined number of transceivers.

The information may comprise an indication of radio conditions.

The method may comprise providing to the network an indication of the number of active transmitters.

The transceivers may comprise at least one of a receiver chain and a transmitter chain. The information may comprise an indication of at least one of an absolute number of transceivers, a delta to a default configuration number of transceivers and an index to a predefined transceiver configuration.

In a fourth aspect there is provided a method comprising providing, to a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode.

The method may comprise determining, based on information associated with the user equipment, the number of transceivers the user equipment should use when operating in a second mode.

The method may comprise receiving from the UE an indication of the number of active transmitters.

In a fifth aspect there is provided an apparatus comprising: at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to: receive, at a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode, determine, based on the information, a number of transceivers to use when operating in the second mode and cause the user equipment to operate in the second mode using the determined number of transceivers.

The information may comprise an indication of radio conditions.

The apparatus may be configured to provide to the network an indication of the number of active transmitters.

In a sixth aspect there is provided an apparatus comprising: at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to provide, to a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode.

The apparatus may be configured to provide, based on information associated with the user equipment, the number of transceivers the user equipment should use when operating in a second mode.

The apparatus may be configured to receive from the UE an indication of the number of active transmitters.

In a seventh aspect there is provided a computer readable medium comprising program instructions for causing an apparatus to perform at least the following receiving, at a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode, determining, based on the information, a number of transceivers to use when operating in the second mode and causing the user equipment to operate in the second mode using the determined number of transceivers.

The information may comprise an indication of radio conditions.

The apparatus may be caused to perform providing to the network an indication of the number of active transmitters.

In an eighth aspect there is provided a computer readable medium comprising program instructions for causing an apparatus to perform at least the following providing, to a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode.

The apparatus may be caused to perform determining, based on information associated with the user equipment, the number of transceivers the user equipment should use when operating in a second mode. The information associated with the user equipment may comprise at least one of mobility information, interference information, network load and radio coverage information.

The apparatus be caused to perform receiving from the UE an indication of the number of active transmitters.

In a ninth aspect there is provided a non-transitory computer readable medium comprising program instructions for causing an apparatus to perform at least the method according to the third aspect or a method according to the fourth aspect.

In the above, many different embodiments have been described. It should be appreciated that further embodiments may be provided by the combination of any two or more of the embodiments described above.

Description of Figures Embodiments will now be described, by way of example only, with reference to the accompanying Figures in which:

Figure 1 shows a schematic diagram of an example communication system comprising a base station and a plurality of communication devices;

Figure 2 shows a schematic diagram of an example mobile communication device;

Figure 3 shows a schematic diagram of an example control apparatus;

Figure 4 shows a schematic diagram of an example 5G network architecture;

Figure 5 shows a flowchart of an example embodiment;

Figure 6 shows a flowchart of an example embodiment.

Detailed description

Before explaining in detail the examples, certain general principles of a wireless communication system and mobile communication devices are briefly explained with reference to Figures 1 to 3 to assist in understanding the technology underlying the described examples.

In a wireless communication system 100, such as that shown in figure 1 , mobile communication devices or user equipment (UE) 102, 104, 105 are provided wireless access via at least one base station (e.g. next generation NB, gNB) or similar wireless transmitting and/or receiving node or point. Base stations may be controlled or assisted by at least one appropriate controller apparatus, so as to enable operation thereof and management of mobile communication devices in communication with the base stations. The controller apparatus may be located in a radio access network (e.g. wireless communication system 100) or in a core network (CN) (not shown) and may be implemented as one central apparatus or its functionality may be distributed over several apparatuses. The controller apparatus may be part of the base station and/or provided by a separate entity such as a Radio Network Controller. In Figure 1 control apparatus 108 and 109 are shown to control the respective macro level base stations 106 and 107. The control apparatus of a base station can be interconnected with other control entities. The control apparatus is typically provided with memory capacity and at least one data processor. The control apparatus and functions may be distributed between a plurality of control units. In some systems, the control apparatus may additionally or alternatively be provided in a radio network controller.

In Figure 1 base stations 106 and 107 are shown as connected to a wider communications network 1 13 via gateway 1 12. A further gateway function may be provided to connect to another network.

The smaller base stations 1 16, 1 18 and 120 may also be connected to the network 1 13, for example by a separate gateway function and/or via the controllers of the macro level stations. The base stations 1 16, 1 18 and 120 may be pico or femto level base stations or the like. In the example, stations 1 16 and 1 18 are connected via a gateway 1 1 1 whilst station 120 connects via the controller apparatus 108. In some embodiments, the smaller stations may not be provided. Smaller base stations 1 16, 1 18 and 120 may be part of a second network, for example WLAN and may be WLAN APs.

The communication devices 102, 104, 105 may access the communication system based on various access techniques, such as code division multiple access (CDMA), or wideband CDMA (WCDMA). Other non-limiting examples comprise time division multiple access (TDMA), frequency division multiple access (FDMA) and various schemes thereof such as the interleaved frequency division multiple access (I FDMA), single carrier frequency division multiple access (SC-FDMA) and orthogonal frequency division multiple access (OFDMA), space division multiple access (SDMA) and so on.

An example of wireless communication systems are architectures standardized by the 3rd Generation Partnership Project (3GPP). A latest 3GPP based development is often referred to as the long term evolution (LTE) of the Universal Mobile Telecommunications System (UMTS) radio-access technology. The various development stages of the 3GPP specifications are referred to as releases. More recent developments of the LTE are often referred to as LTE Advanced (LTE-A). The LTE (LTE-A) employs a radio mobile architecture known as the Evolved Universal Terrestrial Radio Access Network (E-UTRAN) and a core network known as the Evolved Packet Core (EPC). Base stations of such systems are known as evolved or enhanced Node Bs (eNBs) and provide E-UTRAN features such as user plane Packet Data Convergence/Radio Link Control/Medium Access Control/Physical layer protocol (PDCP/RLC/MAC/PHY) and control plane Radio Resource Control (RRC) protocol terminations towards the communication devices. Other examples of radio access system comprise those provided by base stations of systems that are based on technologies such as wireless local area network (WLAN) and/or WiMax (Worldwide Interoperability for Microwave Access). A base station can provide coverage for an entire cell or similar radio service area. Core network elements include Mobility Management Entity (MME), Serving Gateway (S-GW) and Packet Gateway (P-GW).

An example of a suitable communications system is the 5G or NR concept. Network architecture in NR may be similar to that of LTE-advanced. Base stations of NR systems may be known as next generation Node Bs (gNBs). Changes to the network architecture may depend on the need to support various radio technologies and finer QoS support, and some on-demand requirements for e.g. QoS levels to support QoE of user point of view. Also network aware services and applications, and service and application aware networks may bring changes to the architecture. Those are related to Information Centric Network (ICN) and User-Centric Content Delivery Network (UC-CDN) approaches. NR may use multiple input - multiple output (MIMO) antennas, many more base stations or nodes than the LTE (a so- called small cell concept), including macro sites operating in co-operation with smaller stations and perhaps also employing a variety of radio technologies for better coverage and enhanced data rates.

Future networks may utilise network functions virtualization (NFV) which is a network architecture concept that proposes virtualizing network node functions into“building blocks” or entities that may be operationally connected or linked together to provide services. A virtualized network function (VNF) may comprise one or more virtual machines running computer program codes using standard or general type servers instead of customized hardware. Cloud computing or data storage may also be utilized. In radio communications this may mean node operations to be carried out, at least partly, in a server, host or node operationally coupled to a remote radio head. It is also possible that node operations will be distributed among a plurality of servers, nodes or hosts. It should also be understood that the distribution of labour between core network operations and base station operations may differ from that of the LTE or even be non-existent.

An example 5G core network (CN) comprises functional entities. The CN is connected to a UE via the radio access network (RAN). An UPF (User Plane Function) whose role is called PSA (PDU Session Anchor) may be responsible for forwarding frames back and forth between the DN (data network) and the tunnels established over the 5G towards the UE(s) exchanging traffic with the DN. The UPF is controlled by an SMF (Session Management Function) that receives policies from a PCF (Policy Control Function). The CN may also include an AMF (Access & Mobility Function).

A possible mobile communication device will now be described in more detail with reference to Figure 2 showing a schematic, partially sectioned view of a communication device 200. Such a communication device is often referred to as user equipment (UE) or terminal. An appropriate mobile communication device may be provided by any device capable of sending and receiving radio signals. Non-limiting examples comprise a mobile station (MS) or mobile device such as a mobile phone or what is known as a’smart phone’, a computer provided with a wireless interface card or other wireless interface facility (e.g., USB dongle), personal data assistant (PDA) or a tablet provided with wireless communication capabilities, or any combinations of these or the like. A mobile communication device may provide, for example, communication of data for carrying communications such as voice, electronic mail (email), text message, multimedia and so on. Users may thus be offered and provided numerous services via their communication devices. Non-limiting examples of these services comprise two-way or multi-way calls, data communication or multimedia services or simply an access to a data communications network system, such as the Internet. Users may also be provided broadcast or multicast data. Non-limiting examples of the content comprise downloads, television and radio programs, videos, advertisements, various alerts and other information.

A mobile device is typically provided with at least one data processing entity 201 , at least one memory 202 and other possible components 203 for use in software and hardware aided execution of tasks it is designed to perform, including control of access to and communications with access systems and other communication devices. The data processing, storage and other relevant control apparatus can be provided on an appropriate circuit board and/or in chipsets. This feature is denoted by reference 204. The user may control the operation of the mobile device by means of a suitable user interface such as key pad 205, voice commands, touch sensitive screen or pad, combinations thereof or the like. A display 208, a speaker and a microphone can be also provided. Furthermore, a mobile communication device may comprise appropriate connectors (either wired or wireless) to other devices and/or for connecting external accessories, for example hands-free equipment, thereto.

The mobile device 200 may receive signals over an air or radio interface 207 via appropriate apparatus for receiving and may transmit signals via appropriate apparatus for transmitting radio signals. In Figure 2 transceiver apparatus is designated schematically by block 206. The transceiver apparatus 206 may be provided for example by means of a radio part and associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the mobile device.

Figure 3 shows an example embodiment of a control apparatus for a communication system, for example to be coupled to and/or for controlling a station of an access system, such as a RAN node, e.g. a base station, eNB or gNB, a relay node or a core network node such as an MME or S-GW or P-GW, or a core network function such as AMF/SMF, or a server or host. The method may be implanted in a single control apparatus or across more than one control apparatus. The control apparatus may be integrated with or external to a node or module of a core network or RAN. In some embodiments, base stations comprise a separate control apparatus unit or module. In other embodiments, the control apparatus can be another network element such as a radio network controller or a spectrum controller. In some embodiments, each base station may have such a control apparatus as well as a control apparatus being provided in a radio network controller. The control apparatus 300 can be arranged to provide control on communications in the service area of the system. The control apparatus 300 comprises at least one memory 301 , at least one data processing unit 302, 303 and an input/output interface 304. Via the interface the control apparatus can be coupled to a receiver and a transmitter of the base station. The receiver and/or the transmitter may be implemented as a radio front end or a remote radio head.

Figure 4 shows an example 5G radio network architecture 400. The NG-RAN 404 in this example embodiment comprises gNB 401 and gNB 402. The 5G NR architecture allows centralised radio access networks (C-RAN) implementations with one or multiple centralized units (CU) 410 in a gNB 402, each serving a multiple of distributed units (DU) 412. Such CU- DU options are made possible by the interfaces E1 (between the control and user plane in the CU) and F1 (between the CU and DU). The interface between the CU 410 and gnB 401 is an Xn-C interface. The CU shares an interface with the NGC 405.

UE energy consumption is a function of (among other factors) the number of active receiver (Rx) chains. For LTE, UEs typically operate with two Rx antennas (and associated receiver chains), while for 3GPP NR the default number of UE Rx antennas is four, and in some cases (e.g., for mmWave terminals employing beamforming on multiple antenna panels) may be more. The increased number of receive antennas, and the corresponding Rx chain circuitry may offer performance benefits, but at the cost of higher UE complexity and energy consumption, both in terms of analog radio frequency front ends and baseband processing. For RRC Connected mode terminals, the gains from using a higher number of Rx chains may be justified, and immediately visible for the end-user in terms of, e.g., better coverage and higher data rates. The gains are obtained through receiver diversity and/or spatial multiplexing.

For RRC Idle and Inactive mode (where the UE does not have ongoing data transmissions), the primary task of the UE modem will be to conduct radio resource management (RRM) measurements (i.e. Rx operations) and monitor for network related signalling (for instance in case of network originated traffic, that is, paging messages). The measurements are used for managing cell reselections and mobility. Correspondingly, the monitoring for incoming paging messages is an operation may be crucial for the device such that it responds to for instance incoming phone calls or text messages.

Optimising the implementation of multi-antenna techniques for data reception while in RRC connected mode include combinations of analog/digital antenna combining techniques, selection methods, etc. For example, US patent publication no. US2013/0064151 describes adaptive receiver diversity for discontinuous reception, based on decoding a specific paging indicator channel and tracking the error status of that. US patent publication no. US2013/0242772 describes adaptive receiver diversity for discontinuous reception. The control is based on“historical communications” and may include SNR measurements.

For optimizing Idle/lnactive RRM measurements, US patent publication no. US2013/0244665 proposes that UEs shall, by default, only use a single Rx antenna for measurements in Idle mode, and autonomously enable more antenna chains when the reception quality drops below a threshold.

There are numerous studies of (LTE) UE energy consumption. Some of those include estimates of the energy consumption per Rx branch, see for example“Estimation of a 10 Gb/s 5G Receiver’s Performance and Power Evolution Towards 2030” M. Lauridsen, P. Mogensen, T.B. Sorensen, IEEE VTC Fall 2015. In the paper, the energy consumption is estimated for different receiver chain configurations, depending on the number of implemented Low-Noise Amplifiers, mixers and oscillators. A linear scaling is assumed and thus doubling the number of chains also doubles the energy required, but it is worth noting that the number of ADCs and channel bandwidth also plays an important role together with the resulting baseband power consumption.

There are no real power measurements on LTE modems detailing the impact of receive chains, because it is not possible to power ON/OFF individual chains without the vendor’s assistance. However, measurements on Carrier Aggregation (CA) capable LTE phones (“Current Consumption Measurements with a Carrier Aggregation Smartphone”, R. Sanchez- Mejias, Y. Guo, L. Maestro, M. Lauridsen, and P. Mogensen, IEEE VTC Fall 2014) indicate the energy consumption increases ~65 %, when a second carrier is configured. The measurement was performed using inter-band CA, i.e. separate carrier frequencies, and thus an ordinary receive chain, operating in the same band as the main receive chain, will consume less energy because there is no need for additional oscillators.

That is, the deactivation of one or more receive chains may lead to substantial energy savings, however less than the 65% instantaneous current consumption reduction for the case of going from two chains to one chain as observed with CA.

The following reference discusses specifically the anticipated power consumption of NR modems: "GTI Sub-6GHz 5G Device White Paper," 2017. It estimates a receive mode power increase from the 150 mW value with 2 receivers measured for a Cat4 LTE UE to the values of 800 and 400 mW with 16 receivers in NR at 15 kHz and 30/60 KHz subcarrier spacing respectively. Similarly, it estimates a transmit mode power for NR with 8 transmitters of 600 mW and 300 mW for the 15 kHz and 30/60 KHz cases, respectively.

The following relates to mechanisms for implementing a more energy efficient UE, especially when operating in RRC Idle or RRC Inactive modes. RRC Inactive is a new RRC state introduced for 3GPP NR Rel-15. How to efficiently control the number of active UE Rx chains for conducting UE operations while in RRC Idle and Inactive state is addressed below.

Figure 5 shows a flowchart of a method according to an example embodiment. In a first step, S1 , the method comprises receiving, at a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of number of transceivers to use when operating in the second mode.

In a second step, S2, the method comprises determining, based on the information, a number of transceivers to use when operating in the second mode.

In a third step, S3, the method comprises causing the user equipment to operate in the second mode using the determined number of transceivers.

Figure 6 shows a flowchart of a method according to an example embodiment, In a first step, T 1 , the method comprises providing, to a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of number of transceivers to use when operating in the second mode.

The method may comprise determining, based on information associated with the user equipment, the number of transceivers the user equipment should use when operating in a second mode. The information associated with the user equipment may be at least one of mobility information, interference information, network load and radio coverage information.

The first mode may be an RRC connected mode. The second mode may be one of a RRC idle and RRC inactive mode.

The transceivers may comprise receive(Rx)/transmit (Tx) RF chains. The terms Rx chain and Tx chain may be substituted by“antennas”,“antenna panels”,“branches” or“antenna groups”.

The number of transceivers to use when operating in the second mode may be the number of active Rx chains for RRM measurements or measurements of the downlink synchronization channels while in Idle/lnactive state. The information may include an indication of the number of RF chains to be used when in network access mode, e.g., for performing the RACH procedure.

In the following, RRM measurements and number of Rx chains are given as an example use case. It should be noted that, in principle other UE operations such as decoding system information and receiving paging information may be subject to the same concept. That is, a UE may potentially reduce the number of Rx chains when monitoring for paging messages when specific radio conditions are sufficiently good. The potential timers and triggers for such operation may be separate for such functionality.

In an example embodiment, the network informs the UE of the number of active Rx chains that it shall use for (RRM) measurements after it undergoes a RRC state transition from Connected to Inactive, or Idle.

The information from the network to the UE comprising an indication of the number of transceivers to use when operating in the second mode may be conveyed to the UE as part of the general RRC configuration for the device, or by means of dedicated signaling such as, for example, RRC reconfiguration procedures or RRC suspend or release messages. The information may be received (at least partially) when the UE is operating in the second mode (e.g. via SIB signalling). For example, the network may broadcast new event triggering parameters (e.g. A2 threshold) to use in the conditions to determine the number of transceivers to use.

The information may be associated with a BWP (BWP index) such that a given number of RF chains is a function of the BWP to be monitored.

The information may be provided as an absolute number of RF chains, as a delta to a default configuration, or as pointers/index to predefined RF chains configurations.

The information may also convey whether the frequency range 2 (FR2) RF chain may be turned off, relying on frequency range 1 (FR1 ) RF chain. It can be expected that separate RF chains will be utilized for NR operations in FR1 (frequency range of 450 MHz-6 GHz) and FR2 (frequency range of 24.25 - 52.6 GHz) because of the fundamental differences between the two ranges.

The UE shall comply with the information from the network, and only use the number of indicated Rx chains, e.g. while conducting RRM measurements.

In one alternative, the information may provide the maximum number of the RF chains which the UE can use.

When the UE switches back to the first mode, e.g., RRC Connected mode, the UE enables the number of Rx chains used by default while in that state, e.g. 2 for LTE and 4 for NR, unless the default number was overwritten by the network information acquired before moving to Inactive/idle.

The information may comprise an indication of at least one of a first time period, a first mobility event and a first failure event and/or an indication of radio conditions. A mobility event may be one or more reselections. A failure event may be a synchronization failure or cell search failure, or RNAU failure.

For example, the indication coming from the network of a reduced number of Rx chains to use for Idle/lnactive RRM measurements, may be associated with a timer constraint or event constraint (indicated by the first time period, first mobility event or first failure event, respectively). That is, the UE may use a reduced number of Rx chains for a first time period only or until the first mobility event or failure event (e.g., reselection to a different cell) occurs, where after it shall fall back to using more (potentially all) Rx chains. The first time period, X, may be a parameter signaled to the UE from the network. The state transitions may be implemented as gradually increasing the number of antennas to use (potentially with individual timer values) or by abruptly jumping to the default configuration upon timer expiring.

Alternatively, the network may configure the UE with a time pattern associated with a given number of Rx chains e.g. based on the UE/network history in terms of interference vs time of the day and UE mobility pattern.

The network may configure other fail-back criteria for the UE to autonomously switch back to using the full number of Rx chains for Idle/lnactive RRM measurements.

The network may configure the UE to use any of the pre-defined RRM measurement triggering events or a new event for switching back to using the full number of Rx chains for RRM measurements (see 3GPP specs 36.331 and 38.331 ).

For example, the network may configure the UE with event A2 (current cell RSRP/RSRQ below a certain threshold), and hence switch back to using the full number of Rx chains when A2 is triggered (but without necessarily reporting the A2 to the network).

Other examples include using e.g. A3 where a neighbor cell becomes an offset dB better than the serving cell.

The indication of the number of transceivers to use when operating in the second mode may comprise an indication of a number of transceivers to use for a communication type, e.g., QoS or service types, scheduling or procedure types (e.g. configured grant type 1 or type 2).

For example, the UE may be indicated to use 2 Tx to transmit RACH preamble, to use 2 Tx for eMBB transmissions, but to use 4 Tx for configured grant based transmissions of URLLC applications to avoid latency and collisions.

The method may comprise providing to the network an indication of the number of active transmitters. In inactive mode, the UE may provide to the network the change of active number of Tx chains along with RNAU (RAN notification area update) procedure.

In a first example, the method may be deployed in a rural network. Rural deployments with large inter-site distances may be coverage limited (rather than interference limited) and NR deployments are likely to be planned, assuming full usage of UE antennas / Rx chains. That is, the base station deployment is planned under the assumption of the UEs having 4-Rx chains active, providing high diversity gain. This implies that for efficient Idle/lnactive operation, UEs in cell-edge conditions should operate with all 4-Rx chains, while UEs in better conditions may still have sufficiently good Idle/lnactive mode performance using only 1 - or 2-Rx chains, thus achieving power saving.

For a RRC Connected mode UE at cell edge in a rural network (the network is aware from the UEs RRM and CSI measurements), the network will inform the UE to continue using all Rx chains for RRM measurements when it switches to Idle/lnactive RRC mode.

For a RRC Connected mode UE in good coverage conditions (the network is aware from the UEs RRM and CSI measurements), the network will inform the UE upon switching to Idle/lnactive to use a reduced number of Rx chains for RRM measurements when it switches to Idle/lnactive RRC mode.

If the UE is subject to no/marginal mobility, the network may configure the UE to continue using reduced number of Rx chains for a relatively long time period (time duration parameter X in the previous section).

If the UE is subject to medium to high mobility, the network may configure the UE to use the reduced number of Rx chains for only a limited period of time, and potentially also to allow the UE to autonomously switch back to using all Rx chains based on network configured RRM measurements (e.g. event A2 or A3, examples only).

In performing the above, the network may utilize UE mobility information history data to estimate if a UE is a low, medium, or high mobility terminal.

For a RRC Connected mode UE the network may configure the UE with RRC Idle mode configuration that contains triggers for allowing the UE to activate and deactivate the number of receiver chains. That is, if radio conditions are above a certain threshold (like for“special A2” event), the UE is allowed to reduce the number of active receiver chains, while if the conditions are below the threshold, the UE is supposed to use all antennas. For a dense urban deployment, such as a megacity with 50-300 meters inter-site distance, coverage is typically not a problem, as such cases are predominantly interference limited. Only deep indoor users may be coverage limited. As an example, the method may be implemented as follows.

When the interference in the network is moderate, the network may configure UEs to use a limited number of Rx chains for RRM measurements while in Idle/lnactive mode.

As there is a high correlation between network load and interference in the network, the network may choose to configure UEs to use a limited number of Rx chains for RRM measurements (while in Idle/lnactive mode) when the network load is low to moderate.

If there is high network load (i.e. lots of interference), the network may configure UEs to use a higher number of Rx chains for RRM measurements (while in Idle/lnactive mode).

If the network detects that a RRC connected UE has low radio performance (e.g. indicated by reporting of lower CQI values), it indicates that the UE is in challenging radio conditions, and hence it would be riskier to switch to a reduced number of active Rx chains upon transition to Idle/lnactive.

Based on various geolocation information, subscription information, history information, etc., the network may also know that certain UEs are stationary (could e.g. be sensors, cameras, etc.) that therefore may be sufficient to always operate with reduced number of Rx chains, while in Idle/lnactive mode.

The method may provide a set of network controlled procedures to enable the UE to switch off some of its receiver chains for reducing its energy consumption.

The method may provide a network controlled framework for dictating the number of active UE Rx chains, complemented by UE assisted autonomous triggering mechanisms. Both Network and UE information sources are considered when deciding on the number of active UE Rx chains for (RRM) measurements. This may avoid the UE having too many active Rx chains (i.e. spending more energy than needed) versus using too few Rx chains that could cause“attachment/connection losses”, and poor“cell re-selection/mobility performance”, etc. That is, the solution is network controlled, and may benefit from the knowledge available at the network-side. The method may be implemented in a user equipment as described with reference to Figure 2 or a control apparatus as described with reference to figure 3.

An apparatus may comprise means for receiving, at a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode, determining, based on the information, a number of transceivers to use when operating in the second mode and causing the user equipment to operate in the second mode using the determined number of transceivers.

Alternatively, or in addition, an apparatus may comprise means for providing, to a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode, determining, based on the information, a number of transceivers to use when operating in the second mode and causing the user equipment to operate in the second mode using the determined number of transceivers.

It should be understood that the apparatuses may comprise or be coupled to other units or modules etc., such as radio parts or radio heads, used in or for transmission and/or reception. Although the apparatuses have been described as one entity, different modules and memory may be implemented in one or more physical or logical entities.

It is noted that whilst embodiments have been described in relation to LTE and 5G NR, similar principles can be applied in relation to other networks and communication systems where multiple Rx/Tx chains and Idle/lnactive modes are in use. Therefore, although certain embodiments were described above by way of example with reference to certain example architectures for wireless networks, technologies and standards, embodiments may be applied to any other suitable forms of communication systems than those illustrated and described herein.

It is also noted herein that while the above describes example embodiments, there are several variations and modifications which may be made to the disclosed solution without departing from the scope of the present invention.

In general, the various example embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Some aspects of the invention may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The embodiments of this invention may be implemented by computer software executable by a data processor of the mobile device, such as in the processor entity, or by hardware, or by a combination of software and hardware. Computer software or program, also called program product, including software routines, applets and/or macros, may be stored in any apparatus- readable data storage medium and they comprise program instructions to perform particular tasks. A computer program product may comprise one or more computer-executable components which, when the program is run, are configured to carry out embodiments. The one or more computer-executable components may be at least one software code or portions of it.

Further in this regard it should be noted that any blocks of the logic flow as in the Figures may represent program steps, or interconnected logic circuits, blocks and functions, or a combination of program steps and logic circuits, blocks and functions. The software may be stored on such physical media as memory chips, or memory blocks implemented within the processor, magnetic media such as hard disk or floppy disks, and optical media such as for example DVD and the data variants thereof, CD. The physical media is a non-transitory media.

The memory may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processors may be of any type suitable to the local technical environment, and may comprise one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs), application specific integrated circuits (ASIC), FPGA, gate level circuits and processors based on multi core processor architecture, as non-limiting examples.

Example embodiments of the inventions may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

The foregoing description has provided by way of non-limiting examples a full and informative description of the exemplary embodiment of this invention. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of this invention will still fall within the scope of this invention as defined in the appended claims. Indeed, there is a further embodiment comprising a combination of one or more embodiments with any of the other embodiments previously discussed.

Claims

1. An apparatus, said apparatus comprising means for:

receiving, at a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode;

determining, based on the information, a number of transceivers to use when operating in the second mode; and

causing the user equipment to operate in the second mode using the determined number of transceivers.

2. An apparatus according to claim 1 , wherein the information comprises an indication of at least one of a first time period, a first mobility event and a first failure event.

3. An apparatus according to claim 1 or claim 2, wherein the information comprises an indication of radio conditions.

4. An apparatus according to any of claims 1 to 3, wherein the first mode comprises a radio resource control connected mode and the second mode comprises one of a radio resource control idle mode and a radio resource control inactive mode.

5. An apparatus according to any of claims 1 to 4, comprising means for providing to the network an indication of the number of active transmitters.

6. An apparatus according to any of claims 1 to 5, wherein the indication of the number of transceivers to use when operating in the second mode comprises an indication of a number of transceivers to use for a communication type.

7. An apparatus according to any of claims 1 to 5, wherein the transceivers comprises at least one of a receiver chain and a transmitter chain.

8. An apparatus according to any of claims 1 to 6, wherein the information comprises an indication of at least one of an absolute number of transceivers, a delta to a default configuration number of transceivers and an index to a predefined transceiver configuration.

9. An apparatus, said apparatus comprising means for: providing, to a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode.

10. An apparatus according to claim 9 comprising means for:

determining, based on information associated with the user equipment, the number of transceivers the user equipment should use when operating in a second mode.

1 1. An apparatus according to claim 10, wherein the information associated with the user equipment comprises at least one of mobility information, interference information, network load and radio coverage information.

12. A method comprising:

13. A method comprising:

providing, to a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode.

14. An apparatus comprising: at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to:

receive, at a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode;

determine, based on the information, a number of transceivers to use when operating in the second mode; and

cause the user equipment to operate in the second mode using the determined number of transceivers.

15. An apparatus comprising: at least one processor and at least one memory including a computer program code, the at least one memory and computer program code configured to, with the at least one processor, cause the apparatus at least to:

provide, to a user equipment capable of operating in one of a first mode and at least one second mode, information comprising an indication of a number of transceivers to use when operating in the second mode.

16. A computer readable medium comprising program instructions for causing an apparatus to perform at least the following:

17. A computer readable medium comprising program instructions for causing an apparatus to perform at least the following: