GB2631296A

GB2631296A - Improving base station transmission efficiency

Info

Publication number: GB2631296A
Application number: GB2309610.0A
Authority: GB
Inventors: Kulakov Alexey; Pudney Chris; Martins Diogo
Original assignee: Vodafone Group Services Ltd
Current assignee: Vodafone Group Services Ltd
Priority date: 2023-06-26
Filing date: 2023-06-26
Publication date: 2025-01-01
Also published as: WO2025003629A1; GB202309610D0

Abstract

Method and system for managing communications between a user equipment, UE, having a primary receiver and a secondary receiver, and a telecommunications network, the method comprising the UE monitoring characteristics of a radio link between the UE and a base station of the telecommunications network. If the characteristics indicate a degradation of the radio link to a predetermined threshold then powering down the secondary receiver. Providing information to the telecommunications network indicating a receiver status of the UE. The telecommunications network ceasing transmissions to the secondary receiver if the receiver status of the UE provided in the information indicates that the secondary receiver is powered down. The secondary receiver may be a Low Power Wake Up Receiver, LP-WUR, used to reduce the power consumption of the UE. The monitored characteristics may be received signal strength, reference signal received power RSRP, reference signal received quality, RSRQ and/or number of repetitions of a message sent within a predetermined time period.

Description

Improving Base Station Transmission Efficiency

Field of the Invention

The present invention relates to a system, method, and user equipment (UE) for waking up the UE more effectively and efficiently by improving base station efficiency.

Background of the Invention

The battery life of mobile devices or user equipment (UE) is a consideration in 5G systems together with throughput, latency, and reliability. Many operations carried out within individual UEs can affect their battery life. Therefore, there is an aim to achieve improved energy efficiency and so reduce battery consumption. Study Item TR 38.840 in Release 16 (Rel-16) has led to the adoption of different techniques to reduce the UE's power consumption and RP-221543 has introduced further techniques.

In both Release 16 and 17, it was recognized that one procedure that consumes considerable energy in a UE is the paging procedure. The UE can be configured with particular lengths of wake up periods (e.g., in terms of discontinuous reception or DRX cycle). During these times, the UE is able to receive paging signals. The DRX cycle can be extended to allow the UE to sleep for longer periods of time and reduce power consumption, but this leads to increased latency, which is undesirable.

During periods where there is no signalling or data traffic, the UE needs to periodically wake up (e.g., once per DRX cycle) in order to perform coarse synchronization by measuring a synchronization block, so that it can receive a paging message (should one be sent). Figure 1 illustrates this procedure and how the UE changes the power mode of the receiver from deep sleep (DS) to a light sleep (LS) period when it can receive a synchronisation signal block (SSB) burst (where an energy overhead occurs) and back into the DS power mode (see the timing diagram A in Figure 1). The SSB and PO duration may be variable, depending on the Subcarrier Spacing and Cyclic Prefix length. This may be configured by the network. Therefore, Figure 1 illustrates an example configuration.

In Release 17 a new behaviour was introduced involving Paging Early Indication (PEI), as shown in timing diagram B in Figure 1, where the base station (gNB) or the core network indicates to the UE whether to monitor for any Paging Occasions (PO) or not. The PEI indicates to the UE whether or not it is likely to be paged and for the UE to select a power mode appropriately. As shown in timing diagram B of Figure 1, the PEI indicates to the UE not monitor for a Paging Occasion and so the receiver can enter a deep sleep mode and reduce its power consumption.

In Release 18, a new approach requires an additional new low power receiver within the UE. This low power or secondary receiver is separate from the main or primary receiver. When the secondary receiver receives a signal, it wakes the primary receiver. For example, this can occur when the network needs to page the UE (or for other reasons). This secondary or Low Power Wake Up Receiver (LP-WUR) may need to monitor an ultra low power Wake Up Signal (LP-WUS) sent by the base station (gNB) and this can indicate whether or not to wake up the main or primary receiver (allowing the primary receiver to stay in deep sleep mode in the meantime).

However, because the primary receiver can then be configured to remain in a low power or deep sleep mode for longer and the secondary receiver has much less sensitivity than the primary receiver (to reduce power consumption) there is a risk that the low powered secondary receiver misses these LP-WUS signals and fails to trigger the primary receiver to change power mode and become able to receive signals, which increases latency.

Whilst the UE can reduce power consumption by powering down its main receiver, there is also a need to reduce power used by the base station (gNB), where energy use is also important.

Therefore, there is required a method and system that overcomes these problems.

Summary of the Invention

A user equipment (UE), such as a mobile telephone or loT device, contains a primary or main receiver (that is used to communicate with a gNB or base station or a telecommunications network) and a secondary receiver. The secondary or low power receiver uses much less power than the main receiver but cannot receive the majority of signals used to implement cellular communications. The primary receiver can change from operating in a high power mode, where it can receive signals from a base station to a low power mode where it cannot. It may also have other intermediate power mode(s).

If the secondary receiver operates all of the time (even with limited resources), this will still consume some power. Furthermore, the secondary receiver will not be as sensitive as the primary receiver. Therefore, there may be situations when the base station is sending signals to the secondary receiver (attempting to trigger a wake up event) but the secondary receiver is not receiving these signals and so does not wake up the primary receiver or change it to high power mode. This uses power and computing resources for the base station or gNB without any benefit (the UE is unable to receive or act on these signals).

The UE can monitor a radio link with the base station. This can be based on either or both of the primary and/or secondary receivers. If the UE determines that the radio link is below a particular quality or signal level (e.g., based on radio link characteristics) for example, when there is no or little possibility of the secondary receiver receiving a wake-up signal from the base station, then the UE can shut down the secondary receiver (which will save its own computing and battery resources) and transmit data or information (e.g., one or more flags) in a message indicating that this has occurred. Therefore, the UE can inform the telecommunications network of the receiver status of the UE (e.g., that the secondary and/or the primary receivers are powered up or down or the radio link characteristics that have been monitored). The telecommunications network can save its own computing and power resources by refraining from sending further wake up transmissions to the secondary receiver of this particular UE when it is informed or can infer from the received information that the secondary receiver can no longer receive transmissions (i.e., because it is powered down).

In accordance with a first aspect, there is provided a method for managing communications between a user equipment, UE, having a primary receiver and a secondary receiver, and a telecommunications network, the method comprising the steps of: the UE monitoring characteristics of a radio link between the UE and a base station of the telecommunications network; if the characteristics indicate a degradation of the radio link to a predetermined threshold then powering down the secondary receiver; providing information to the telecommunications network (e.g., by transmitting this from the UE to the telecommunications network) indicating a receiver status of the UE; and the telecommunications network ceasing transmissions to the secondary receiver if the receiver status of the UE provided in the information indicates that the secondary receiver is powered down. Therefore, the telecommunications network can reduce bandwidth use (on the band used by the secondary receiver) and reduce power consumption because it does not send unnecessary transmissions to the secondary receiver of the UE, when the secondary receiver (of a particular UE) is powered down.

Preferably, the method may further comprise the steps of: the UE powering up the secondary receiver; the UE providing the telecommunications network with further information indicating the receiver status of the UE; and the telecommunications network resuming transmissions to the secondary receiver if the receiver status of the UE provided in the further information indicates that the secondary receiver is powered up. Therefore, the telecommunications network can be aware of when the UE is both not able to receive signals (i.e., wake up messages) using its secondary receiver and when it is again able to receiver signals using its secondary (low power) receiver and respond by resuming transmissions, accordingly.

Advantageously, the UE may power up the secondary receiver in response to determining that the characteristics indicate an improvement of the radio link to a second predetermined threshold. Therefore, the UE can monitor the radio link when the secondary receiver is both active and powered down. The second predetermined threshold may be optionally set to a different value (e.g., set at a level to indicate a higher quality link) than the first predetermined threshold. This provides a hysteresis to avoid powering up and down the second receiver repeatedly when the radio link hovers around a particular level or threshold.

Optionally, the transmissions to the secondary receiver may be transmissions causing the UE to change a power mode of the primary receiver from a second power mode to a first power mode, wherein the primary receiver consumes more power in the first power mode than when in the second power mode. Therefore, the transmission to the secondary receiver may be wake up signals or contain wake up messages. The primary receiver may be powered down (at least partially) but carry our at least a background process to detect signals received from the secondary receiver (generated in response to receiving a radio signal) causing the primary receiver to fully power up.

Optionally, the monitored characteristics of the radio link between the UE and a base station may include any one or more of: received signal strength; reference signal received power, RSRP; reference signal received quality, RSRQ; and/or number of repetitions of a message sent to the secondary receiver within a predetermined time period. Other characteristics or parameters may be measured. The number of repetitions of a message sent to the secondary receiver within a predetermined time period may indicate that the secondary receiver is only receiving a small subset of message that are sent to it. If too many failures are detected (e.g., because the telecommunications network monitors how many transmissions are not acknowledged and informs the UE when it does become available) then the secondary receiver may be powered down or other actions taken (e.g., keeping the primary receiver active for a longer periods).

Optionally, the UE may be in radio resource control, RRC, idle mode or RRC inactive mode. The UE may also be in other modes during the time that the method executes.

Preferably, the information indicating the status of the secondary receiver provided to the telecommunications network may include an identifier of the UE. This may be a unique identifier and/or an identifier assigned by the telecommunications network.

Optionally, the identifier of the UE may be an inactive radio network temporary identifier, I-RNTI, assigned by a radio access network, RAN. Other identifiers may be used (especially when the UE is in different RRC modes).

Optionally, the information indicating receiver status of the UE (which may be used to indicate that the secondary receiver is powered down) may be transmitted to the telecommunications network within a scheduled uplink physical uplink shared channel, UL PUSCH, transmission. Other communication channels may be used.

Optionally, the method may further comprise the steps of: the UE moving to a new base station; and the new base station retrieving from the original base station the information indicating that the receiver status of the UE. Therefore, the telecommunications network does not need to send unnecessary transmissions to the secondary receiver of the UE even when the UE moves to a different cell site.

Optionally, the identifier of the UE may be a serving temporary mobile subscriber identity, S-TMSI, assigned by a core network. Other identifiers may be used (especially when the UE is in different RRC modes).

Optionally, the information indicating the receiver status of the UE may be transmitted to the telecommunications network within a radio resource control (RRC) communication between the UE and the base station. Other communication methods may be used.

Optionally, the step of providing information to the telecommunications network indicating the receiver status of the UE may be transmitted by the UE when the UE is in RRC idle mode. The telecommunications network may put the UE into RRC connected mode to receive the receiver status, but this is not necessary. The receiver status may be transmitted by the UE to the telecommunications network and the connection may be released without the UE being connected.

Optionally, the method may further comprise the step of a core network providing the base station with information indicating the receiver status of the UE. Therefore, the base station (gNB) may be able to cease sending signals to the secondary receiver of a particular UE even though the UE is not in RRC connected mode and does not have an assigned identifier.

Optionally, the core network may provide the base station with the information indicating the receiver status of the UE at the same time as paging the UE. Therefore, no wake up message needs to be sent (as the base station will be aware that this message is not receivable by the UE).

Optionally, the method may further comprise the step of the base station issuing a RRC message to the UE causing the UE to release connection with the base station.

Optionally, the step of providing information to the telecommunications network indicating the receiver status of the UE may be transmitted by the UE when the UE is in RRC connected mode.

Advantageously, the receiver status of the UE may be transmitted by the UE within a UE assistance information message. Other formats or message types may be used.

Optionally, the method may further comprise the step of the base station storing the receiver status of the UE.

Optionally, the base station may associate the stored receiver status of the UE with a context of the UE. For example, the context of the UE may be an RRC mode (idle, inactive, etc.). Therefore, this information may be used by the base station or provided to the core network once a connection between the base station and the UE ends.

Optionally, the information provided to the telecommunications network indicating the receiver status of the UE may comprise any one or more of: a powered up or a powered down status of the primary receiver; and/or a powered up or a powered down status of the secondary receiver. This may be included explicitly within a message or encoded within a message (e.g., using a particular bit or flag within an existing message).

According to a second aspect, there is provided a telecommunications network comprising: one or more base stations; one or more UEs; and means adapted to perform the method according to any previous claim. The UEs and/or base stations may be configured to operate any of the methods described above.

The above described methods may be implemented together with the following operating at the UE. As described previously, in the low power mode, the primary receiver can continue with some limited operations, such as those that control or change the power mode of the primary receiver. For example, the primary receiver can contain a timer so that it switches from low power mode to high power mode at intervals so that the UE can check if any signals are being transmitted to the UE by a telecommunications network. If no signals are received by the primary receiver, then it may return to the low power or sleep mode after a predetermined period. The primary receiver can also be changed to high power mode when it is triggered by the secondary receiver. This occurs when the secondary receiver receives a signal from the base station.

Because the secondary receiver has to operate all of the time it must do so with limited resources. Furthermore, it will not be as sensitive as the primary receiver, which requires more power when it is operating in the high power mode. Therefore, there may be situations when the base station is sending signals to the secondary receiver (attempting to trigger a wake up event) but the secondary receiver is not receiving these signals and so does not wake up the primary receiver or change it to high power mode.

During this time, the UE is not in communication with the network. When the primary receiver changes from low power mode to high power mode (wakes up) it can then receive any missed signal or message that the network has been trying to send. The network includes in this signal data or information that the UE or primary receiver uses to alter how the primary receiver changes its power mode. For example, the network will be aware whether or not the UE has missed any messages and how often they are missed. If they are missed very regularly then the information can indicate that the primary receiver should stay in its high power mode for longer than usual.

Alternatively or additionally, the information can include an indication of the number of signals that were missed by the secondary receiver before it successfully received one and woke up the primary receiver. The UE can compare this with a threshold (e.g., three missed signals). If the number of missed signals is equal or greater than the threshold then the primary receiver determines that it should remain in the high power mode for longer than usual. The information can also change the threshold number and/or the time (e.g., updates a parameter) that the primary receiver remains in the high power mode. The information may also alter (increase or decrease) the timeout time for remaining in sleep or low power mode before returning to high power mode.

Whilst this information that affects how the power mode of the primary receiver is changed is contained with the signals sent to the primary receiver, such information may alternatively or additionally be included in the signals sent to the secondary receiver. Therefore, even if the secondary receiver is missing a certain percentage or ratio of signals, some may get through and can be processed. Therefore, the secondary receiver can pass this information to the primary receiver (or another processor) for processing.

The information may also change the parameters in the other direction so that the primary receiver remains for longer in sleep or low power mode (e.g., if few or no signals are missed by the secondary receiver).

The methods described above may be implemented as a computer program comprising program instructions to operate a computer. The computer program may be stored on a computer-readable medium, including a non-transitory computer-readable medium.

The computer system may include a processor or processors (e.g., local, virtual or cloud-based) such as a Central Processing Unit (CPU), and/or a single or a collection of Graphics Processing Units (GPUs). The processor may execute logic in the form of a software program. The computer system may include a memory including volatile and nonvolatile storage medium. A computer-readable medium may be included to store the logic or program instructions. The different parts of the system may be connected using a network (e.g. wireless networks and wired networks). The computer system may include one or more interfaces. The computer system may contain a suitable operating system such as UNIX, Windows (RTM) or Linux, for example.

It should be noted that any feature described above may be used with any particular aspect or embodiment of the invention.

Brief description of the Figures

The present invention may be put into practice in a number of ways and embodiments will now be described by way of example only and with reference to the accompanying drawings, in which: Fig. 1 shows a schematic illustration of the timing of signals between a network and user equipment (UE); -10 -Fig. 2 shows a schematic diagram of a system for initiating communications between the network and the UE; Fig. 3 shows a flowchart of a method for operating the system of Figure 2; Fig. 4 shows a further method for operating the system of Figure 2; Fig. 5 shows a further method for operating the system of Figure 2; Fig. 6 shows a further method for operating the system of Figure 2; Fig. 7 shows a further method for operating the system of Figure 2; Fig. 8 shows a sequence diagram of a method for operating the system of Figure 2; Fig. 9 shows example messages used within the method of Figure 8; and Fig. 10 shows a sequence diagram of a method for operating the system of Figure 2.

It should be noted that the figures are illustrated for simplicity and are not necessarily drawn to scale. Like features are provided with the same reference numerals.

Detailed description of the preferred embodiments

A low power secondary receiver is used to wake up a primary receiver, which has different characteristics to the primary receiver in a new radio (NR) user equipment (UE). Preferably, the secondary receiver has reduced complexity so that the primary receiver can be powered down more often whilst keeping the secondary receiver operational and the overall system can then consume less power. This difference and energy saving can be considerable. The primary receiver is configured to receive certain types of signals (e.g., a first signal or a first signal type) and the secondary receiver is configured to receive a different type of signals (e.g., a second signal or a second signal type). Therefore, the secondary receiver (i.e., a Low Power Wake up Receiver -LP-WUR) consumes less power than the primary receiver (e.g., by at least a factor of 10). To allow this lower complexity, the type of signal that is received by the secondary receiver should also follow a simpler design. The characteristics of such a new (second) signal LP-WUS (Low power wake up signal) can comprise but is not limited to: 1) Lower modulation order (00K, FSK); and 2) Smaller amount of data to be transmitted The second signal (LP-WUS) may in some situations be a replacement for (or in addition to) the PEI (Paging Early Indication) functionality, as shown in the timing diagram B of Figure 1, or to be used as trigger to monitor one or more Paging Occasion, e.g., by monitoring the Physical Downlink Control Channel (PDCCH) in the primary receiver, as shown in timing diagram A in Figure 1.

The secondary receiver (LP-WUR) can have a simpler architecture, with lower cost and complexity components when compared with the primary receiver, as the demodulation of the wake up (second) signal will not be as complex as the demodulation of a legacy signal received by the primary receiver, e.g., a NR channel/signal.

For example, the receiver architecture for the secondary receiver may be based on: 1) RF Envelope detection; 2) Heterodyne architecture with Intermediate Frequency envelope detection; 3) Homodyne/zero-Intermediate Frequency architecture with baseband envelope detection; and 4) FSK (Frequency Shift Keying) receiver.

These secondary receiver architectures are optimised for a lower power consumption when compared to the primary receiver, at the cost of lower receiving sensitivity. Primary or main receiver sensitivity values can be found on TS 38.101-1 and can be as low as -96.8 dBm for the reception of a Quadrature phase-shift keying (QPSK) signal for n1 with 15 kHz SCS with a 2RX receiver. For comparison, the type of architectures mentioned above for the secondary receiver can have sensitivity values between -50 to -90 dBm.

By having lower receiving sensitivity when compared to the primary receiver, depending on the second signal (LP-WUS) design, the secondary receiver (LP-WUR) may have coverage performance degradation and so will not always be able to detect the second signal (LP-WUS) indicating that the UE is to be paged. Therefore, there may be no trigger to wake up the primary receiver and so paging (or other) messages may be missed when transmitted by the base station, gNodeB or gNB. If the UE is not able to be paged due to coverage issues from the non-detection of the second signal (LP-WUS), caused by the lower sensitivity of the secondary receiver (LP-WUR), the UE may be left in a state where it doesn't wake up as it was not triggered by the secondary receiver (LP-WUR). This can leave the UE not able to receive paging messages even in the absence of coverage level issues (i.e., if the primary receiver was in a high power mode).

-12 -At the same time, the base station (gNB) does not know the signal level, characteristics or quality, as encountered by the UE. For example, these may include any one or more of received signal strength, reference signal received power (RSRP), reference signal received quality (RSRQ) and/or number of repetitions of a message sent to the secondary receiver within a predetermined time period (i.e., that failed and had to be repeated until acknowledged). These receiver signal characteristics or monitored radio link characteristics may be measured by the main and/or secondary (LP-WUS) receivers when the device is in IDLE/Inactive modes and does not send measurements to the network, for example. As a consequence, the telecommunications network and/or radio access network (RAN) may page the device using the secondary receiver (LP-WUS) and normal physical downlink control channel (PDCCH) to ensure paging is received.

Sending on a regular basis two signals to the same device increases energy consumption of the telecommunications network. This may be calculated for a typical network to increase energy consumption by between 0.002% and 1.724% according to simulation results. Avoiding transmission of signals where the corresponding receiver cannot receive them (because the radio link is below a particular quality or value) can improve energy efficiency by up to this amount.

Should the UE not be able to receive wake up signals using the secondary receiver then the UE may fallback to a legacy paging monitoring procedure, i.e., using the primary receiver (with higher sensitivity and corresponding power demands). Therefore, paging messages can be received and decoded in the circumstances where the primary receiver outperforms the secondary receiver (LP-WUR), i.e., in terms of coverage level and radio link quality.

Although the aim of employing a LP-WUR/LP-WUS (second signal/secondary receiver) mechanism is to wake up the primary or main radio when it is triggered by the network, this does not require the primary receiver to be completely shut down. It will instead change to a deeper sleep state and not be completely shut off.

There may be several different power modes or sleep states. An ultra-deep sleep or lowest power mode may be defined relative to a fully active state. The active or highest power state or mode may have a relative power unit of 1. The ultra-deep sleep power state -13 -may consume approximately 0.015 times the power of the active state of the primary receiver. This may be found in TR 38.869.

Figure 2 shows a schematic diagram of a system 10 that incorporates a UE 20 and a base station (gNB or gNodeB) 30 connected to other parts of the telecommunications network 70. The system 10 may include a plurality of base stations 30 and many UEs 20 but Figure 2 only shows a single UE 20 and base station 30 for simplicity.

The primary receiver 40 and the secondary receiver 50 are shown within the UE 20.

Both receivers are shown as being connected to antenna 90 of the UE but there may be separate antennas and each receiver may have its own antenna in certain alternative implementations. A processing means 60 is illustrated with the primary receiver 40 but such processing means may be located elsewhere. The base station 30 also has its own processor 80 that controls how and when the first and second signals are sent from the base station 30 using an antenna 85.

In Figure 2, the system of the first signal 45 is shown between the base station 30 and the primary receiver 40. The second signal 55 is shown schematically also between the base station 30 and the secondary receiver 50. The secondary receiver 50 is shown in communication with the primary receiver 40. In particular, when the secondary receiver 50 receives the second signal 55, a trigger 25 is sent from the secondary receiver 50 to the primary receiver 40, which is processed by the processing means 60 of the primary receiver to change the power state of the primary receiver 40 from any low power modes to a high (or higher) power mode enabling the primary receiver 40 to receive the first signal 45 from the base station 30.

In an example implementation where the first signal is a paging signal, the UE 20 may be paged in an area that may be a tracking area or a RAN based notification area (RNA) depending on the state of the UE 20 (Idle or Inactive). This may include multiple cells. The UE 20 needs to know if a particular cell will support the new signal architecture described above. This indication may be configured as a wake up signal (WUS) configuration (e.g., as part of DownlinkConfigCommonSlB IE within SIB1) and may be sent by the base station (gNB) 30 to all UEs 20. If WUS is supported by the cell (e.g., base station 30) and the UE 20 has a corresponding capability, which is indicated previously to the base station 30, the base station 30 may use the WUS signal to wake up the UE 20.

-14 -The other parameter associated with a new signal might be the payload of the signal; a number of paging locations associated with the signal; UE identity or UE group identity formats, in case there are different supported formats; Physical layer parameters to assist the UE 20 in monitoring of a new signal; or other parameters.

One of the parameters which may be provided to the UE 20 within a system information block (SIB), e.g., SIB1, may be a fallback threshold. There are at least two alternative ways in which the fallback procedure may be implemented.

Alternative 1: An internal clock 65 of the primary receiver or radio 40 is kept running in order to maintain synchronisation of different components. Furthermore, the processing means 60 of the primary receiver is also capable of receiving the wake up instruction or trigger 25 from the secondary receiver 50 (LP-WUR). Even with this functionality, a low power state of the primary receiver 40 can be maintained. The internal timer 65 is monitored by the primary receiver 40 to wake up or return to a high power mode, if no wake up instruction or trigger 25 has been provided by the secondary receiver 50 (LP-WUR) within a time threshold (either static or dynamic). Such a time period may be 1-2 hours, for example.

Procedurally, this behaviour may be described as the following example scenario: 1) Internal timer 65 of the primary receiver 40 is set to 0 (or reset) when the primary receiver 40 is turned on (i.e., changes to a high power mode of operation). The internal timer 65 starts to run as soon as the primary receiver 40 changes power mode to a low power mode (e.g., its ultra-deep sleep mode); 2) Normal functioning of the secondary receiver 50 (LP-WUR) occurs, with the UE 20 having a coverage level that allows it to receive the second signal 55 (LP-WUS) and trigger the primary receiver 40, waking it up if necessary. Timer 65 is set to 0 (e.g., seconds or minutes) again whenever primary receiver 40 is changed to its high power mode (wakes up). Timer 65 starts to run when the primary receiver 40 goes back to a low power mode (e.g., ultra-deep sleep); 3) Coverage level degradation is observed, secondary receiver 50 (LP-WUR) is not able to receive the second signa (LP-WUS) 55. The timer 65 continues to run; 4) When the timer 65 reaches a given threshold (e.g., 2 hours), it automatically wakes the primary receiver 40, which can attempt to monitor for paging occasions (PO) following legacy procedures, going back to sleep (low power mode) if no paging message -15 -has been received over a second time period, which may be defined as a preconfigured number of discontinuous reception (DRX) cycles. The timer is set to 0 as the primary receiver 40 wakes up and if there are no received paging messages, then the primary receiver 40 goes back to sleep and sets the timer 65 to run again; and 5) Step 3), 4) may continue until coverage level degradation is not observed by the secondary received (LP-WUR) 50, i.e., returning to Step 1).

Alternative 2: Another method that provides a mechanism for the primary receiver 40 to fallback to the legacy paging monitoring procedure is to have the base station 30 (gNB) indicate a number of False Paging receptions, i.e., how many times the base station 30 transmitted the second signal 55 without the primary receiver 40 changing to the high power mode and/or received the first signal 45. This may be defined as a failure ratio or other value. This may be indicated (to the network or base station 30) by failure of the primary receiver 40 (which may include or be linked to a transmitter) in responding to a first signal 45 (e.g., a paging message). A threshold may be predetermined for such false paging reception (i.e., number of repetitions that were required until success) and this threshold may be part of the WUS configuration (similar to the fallback threshold or second time period in alternative 1, described above).

As paging is UE specific, the base station 30 knows how many paging messages (or other first signals 45) following second signals 55 have been sent to a particular UE 20 and how many messages are received back from it, establishing a rate or ratio of Paging Reception Failures. If the base station 30 can report this ratio (or data indicating this ratio) to the UE, it can provide information for the UE 20 to fallback to the legacy paging monitoring procedure. Furthermore, this information can indicate characteristics of the radio link between the UE and the base station. This ratio can be sent in the second signal 55 (LP-WUS) or be included in information with the first signal 45 (when eventually received). Depending on a threshold of this ratio or a number, the UE 20 may fallback to the legacy procedure.

Procedurally, the behaviour may be described as the following example scenario: 1) Normal functioning of the secondary receiver 50 (LP-WUR) being in a coverage level that allows it to receive the second signal 55 (LP-WUS) and trigger the primary receiver or radio 40 to wake up when necessary. When there is a trigger 25 for the -16 -primary receive change from a low power mode to a high power mode (woken up), the first signal 45 (and/or a second signal 55, if received) contains the Paging Reception Failures ratio or number. The main receiver 40 stores this ratio, number or other indication of this value; 2) For every occasion where the primary receiver 40 and/or the UE 20 is woken up (changed from low to high power mode), a new ratio may be received and the stored ratio may be updated within the primary receiver 40 or elsewhere within the UE 20. Even though this value or ratio may not be received every time, once received, the UE 20 can become aware of the current failure range or rate; 3) When the ratio reaches a threshold provided in the WUS configuration (or elsewhere), it automatically wakes the primary receiver 40 so that it may perform the legacy paging monitoring procedure; and 4) The criteria to fallback again to the LP-WUR mechanism (i.e., being triggered by the secondary receiver 50) may occur when the coverage level of the secondary receiver 50 (LP-WUR) can be maintained, i.e., operating according to step 1).

The process may fall back to using the secondary receiver 50 (LP-WUR) after a time period defined as a number of discontinuous reception (DRX) cycles, which could also be defined as part of WUS configuration.

Alternatives 1 and 2 may be combined or operate in isolation.

Figure 3 shows a flowchart of a method 100 for operating the system 10 shown in figure 2. The method 100 starts with the primary receiver 40 in low power mode at step 110. As described previously, during the low power mode the primary receiver 40 can carry out some operations such as running the timer 65 but cannot receive the first signal from any base station 30.

At step 120, the secondary receiver 50 receives the second signal 55. This causes a trigger 25 to be sent internally within the UE 20, which causes the primary receiver 40 to switch from low power mode to high power mode at step 130. The primary receiver 40 is therefore in a power mode that enables it to receive the first signal 45 from the base station 30 when it is set.

At step 140, the primary receiver 40 receives the first signal 45 from the base station 30. The first signal 45 includes information or data that the primary receiver 40 can -17 -use to alter parameters that control how the power mode of the primary receiver 40 is changed. At step 150, the information within the first signal 45 (or alternatively or additionally within the second signal 55) received by the primary receiver 40 is used to alter these parameters so that the power mode of the primary receiver is changed in a different way to how it was operating before it received the first signal 45. Therefore, the power modes for the primary receiver 40 can be changed in a more optimal way depending on the location of the UE 20 and how effective the secondary receiver 50 is at receiving the second signals 55. For examples, these parameters can change and switch between the two alternative methods described above or provide additional functionality for changing how the power mode of the primary receiver 40 is altered under different circumstances and radio conditions. At step 160, the power mode of the primary receiver 40 is controlled according to the altered (or unaltered) parameters. For example, the primary receiver 40 may remain in its high power mode for longer than normal.

Whilst figure 3 shows the method 100 starting with the primary receiver 40 (primary RX) in the low power mode, it may also start at a different point in the cycle with the primary receiver in the high power mode 40. At this starting point, the primary receiver 40 can receive the signal containing the information (step 140) and use the information to alter the parameters controlling its power mode (step 150). When using these parameters to control the power mode (step 160) the primary receiver 40 will eventually revert to the low power mode (see arrow back to step 110), where the secondary receiver 50 waits to receive the second signal 120, which wakes the primary receiver 40 (step 130) and the cycle can repeat.

Figure 4 shows a further method 200 for operating the system 10 of Figure 2. This method 200 includes the same method steps as that of method 100 but operates a further parallel procedure in which the primary receiver 40 can fall back to operating in a high power mode even when the secondary receiver 50 fails to receive any second signals 50 from the base station 30 and/or the trigger signal 25 fails to wake the primary receiver 40.

Either process can be used to change the power mode of the primary receiver 40 from low power to high power. With the primary receiver starting in low power mode (step 210) the timer 65 runs until a first time period (timer 1) reaches a time threshold or expires (step 220). After timer 1 has expired then the primary receiver 40 changes from low power mode to high power mode at step 230. The time 65 (or a different timer) may be reset to -18 -zero and when the high power mode is set and then runs until a second timer (timer 2) reaches a second time period or threshold at expiration of this second time period at step 240. The primary receiver 40 then changes from the higher power mode to the low power mode at step 250 where timer 1 is reset to zero and is then monitored until timer 1 reaches the first time period value.

The information within the first signal 45 can alter different parameters that control how the power mode of the primary receiver 40 operates. For example, the information may alter either or both of timer 1 and timer 2 (i.e., their expiration or trigger times).

Therefore, altering the timer 2 expiry time can be used to increase or decrease the time that the primary receiver 40 is in a high power mode and able to receive the first signal 45. For example, if the network 70 considers it likely that the UE 20 will need to be paged more often, then it can include an alteration to the expiry value of timer 2 in the first signal 45 keeping the primary receiver 40 in high power mode for additional DRX cycles, for example. Whilst this uses more power, it can reduce latency. The information within first signal 45 can either temporarily or permanently adjust the expiry time of timer 2. For example, the information may change the timer 2 expiry by a number of DRX cycles or for a particular time with such information also included within the first signal 45. Conversely, when no paging is expected for the UE 20 then the expiry time of timer 1 can be increased and/or timer 2 can be decreased saving power.

The information contained within the first signal 45 may indicate how many second signals 55 have been missed before the UE 20 responds to the base station 30 in a paging or otherwise situation. This ratio or absolute number can be used by the UE 20 or primary receiver 40 to adjust timer 1 and or timer 2 expiry times. For example, when this ratio or number indicates a threshold has been reached then (i.e., too many wakeup signals 55 have been missed or a failure rate has been breached) then the primary receiver 40 can be kept in the higher power mode for longer by increasing the timer 2 expiry time and/or reducing the time that the primary receiver 40 sleeps or remains in the low power mode by reducing the timer 1 expiry time. Again, these changes may be temporary (i.e., expire or revert after a set period) or be permanent, as defined in the information received in the first signal 45.

The thresholds themselves may also be altered as parameters for controlling how the primary receiver power mode is changed. For example, the network 70 may decide -19 -that this threshold is rarely breached and so may increase the threshold number or ratio that is acceptable before temporarily increasing the timer 2 expiry time to keep the primary receiver 40 within the high power mode for longer. This can go in both directions.

Figure 5 shows a flowchart of a further method 300 for operating the system 10. In this example, the primary receiver 40 starts the process in the high power mode (310) and is able to receive signals containing the information to alter the parameters that control how the primary receiver 40 is changed (steps 140, 150 and 160). At some point in this process, the primary receiver 40 will have its power mode changed from the high power mode to low power mode (arrow from 160 to step 330), when it can no longer receiver signals but can operate the timers. In parallel, timers 1 and 2 operate to periodically change the power mode of the primary receiver between high power mode and low power mode (steps 320, 330, 340 and 350). The thresholds of these timers may also be altered using the information contained within the signal received by the primary (or secondary) receiver 40. Whenever the information is received or changed then the operation of the method 300 may be adjusted.

The method described with reference to figures 3, 4, and 5 provide the UE with an improved operation technique for ensuring that latency is reduced as much as possible. However, this still leaves the base station transmitting signals to the secondary receivers of particular UEs that are unable to receive them because of the current characteristics of the radio link between the UE and the base station. Therefore, the UE 20 can monitor these characteristics and power down or shut down the secondary receiver 50 if the radio link is insufficient for wake up (or any other) signals to be received by it and also inform the telecommunications network 70 that this has been done so that it may cease (at least temporarily) transmitting signals to the secondary receiver 50 that will not be received. The UE 20 can keep monitoring the radio link characteristics and restart or power up its secondary receiver 50 when these characteristics indicate that transmissions will be received. It may do this my monitoring the radio link characteristics of the primary receiver 40 as these may be used to determine whether or not the (lower power and sensitivity) secondary receiver 50 could receive signals in the same environment.

In order to save energy the telecommunications network 70 should preferentially not send LP-WUS signals to UEs which are out of coverage of the low power WUS. However, if a particular UE 20 is in radio resource control (RRC) Idle or RRC Inactive mode, then the telecommunications network 70 does not know if the device is capable of receiving the LP- -20 -WUS signal. The telecommunications network 70 is expected to continue to send paging messages over the air interface, irrespectively if the device is listening to PDCCH / paging / PEI (i.e., whether or not the primary receiver is on or off).

Figure 6 shows a flowchart of an example method 600 for operating the UE 20 of Figure 2. This method 600 operates as computer code executed within the UE 20. As can be seen from Figure 6, the method 600 operates as an ongoing loop with the method 600 returning to the step of monitoring radio link characteristics 610 between the UE 20 and the base station 30. When the characteristics indicate that radio link has degraded to below a particular (first) threshold (that may be defined and compared in different ways) and shown at step 620, then a check is made to determine if the secondary receiver 50 is powered and/or operational (step 630). If not, then the method 600 returns to the monitoring step (610). If the secondary receiver 50 is operational but the radio link has degraded below the first threshold, then the secondary receiver is powered down at step 640 and the receiver status is transmitted to the telecommunications network 70 (step 650).

The radio link characteristics continue to be monitored. If the radio link improves past a second threshold (step 660) that may be the same or higher than the first threshold, then the method 600 checks if the secondary receiver 50 is powered (step 670) if not then monitoring continues. If the secondary receiver 50 is not powered, then it is powered up at step 680 and the receiver status is again sent to the telecommunications network 70 (step 650) and monitoring continues.

Figure 7 shows a flowchart of a method 700 for operating at the base station 30 while the method 600 is operating (i.e., at one or more UEs within the cell serviced by the base station 30). At step 710 the base station 30 receives the receiver status transmitted by the UE 20. If the receiver status indicates that the secondary receiver 50 is powered (step 720), then the base station 30 will continue to transmit the wake up signals to it at step 730 (or start to transmit wake up signals if it had previously received an indication that the secondary receiver 50 of the UE20 had been powered down). If the information received from the UE 20 indicates that the secondary receiver 50 of a particular UE 20 has been powered down then the base station 30 will cease (or continue to refrain from) sending wake up signals to the secondary receiver 50 of the UE 20.

-21 -The following provides example implementations with the UE 20 in RRC Inactive and IDLE Modes.

Figure 8 shows a sequence diagram 800 of method steps carried out with the UE 20 in Inactive mode. The following step numbers (0-4) correspond to those shown in Figure 8.

STEP 0: During an initial connection to the telecommunications network 70 (when the primary or main receiver 40 is on), the radio network (serving base station or gNB 30) assigns the UE 20 with a UE identifier to be used to inform the telecommunications network if LP-WUR status is on or off (i.e., the receiver status of the UE 20). With the UE 20 in inactive mode, the identifier used may be an inactive radio network temporary identifier (IRNTI) -full or short. Any other ID given to the UE 20 by the RAN network can be used for this propose.

STEP 1: The UE 20 (device) decides to switch on or off LP-WUR (secondary receiver 50) according to the method 600 described with reference to Figure 6. This decision might be based on specific thresholds based on hysteresis parameters that may be adjusted (e.g., over system information) to avoid frequent switching off and on of low power (secondary) receiver 50.

With the UE 20 in inactive mode (no radio connection to the RAN exists, but the UE context is known within the RAN=gNBs level), the UE 20 can use a legacy mobile originated procedure (using RACH or configured grants) to be able to send msg 3 (i.e., scheduled UL (PUSCH) Transmission) carrying RRC message (e.g., RRC connection resume) including the UE identity, plus information indicating the LP-WUR or receiver status. There may be other UEs included in this message, e.g., MAC-I to enable the base station (gNB) 30 to identify the context in a secure way). The UE receiver status (e.g., LPWUR) can be determined in different ways (e.g., based on different or new cause values within the RRC resume request or using a spare bit within RRC resume request).

STEP 2 and STEP 3 (Optional): If the UE 20 moves between base stations (gNBs) and the receiver (e.g., LPWUR) status needs to be delivered, the context of the UE 20 needs to be retrieved from the last used base station (gNB) 30 to the new base station.

-22 -STEP 4: Once the new receiver (e.g., LP-WUR) status is known by the serving base stion 30 the procedure may end with a RRCRelease or RRCReject message, which allows the UE 20 to remain in inactive mode.

Figure 9 illustrates three example messages 910, 920, 930, used in the method described with reference to method 800 of Figure 8.

The following describes a further example implementation method 1000 with the UE 20 in RRC idle mode. This method 1000 is shown as a sequence diagram in Figure 10.

The following steps correspond to those shown in Figure 10.

STEP 0: This takes place during the initial connection to the telecommunications network 70, e.g., with the main or primary receiver 40 on. The core network (CN) assigns a UE identifier to be used to inform the core network of the UE receiver status (e.g., if the LP-WUR or secondary receiver is on or off). With the UE 20 in idle mode, the UE identifier may be a serving temporary mobile subscriber identity (S-TMSI). This may be 40 bits in LTE and 48 bits in 5G.

STEP 1-3: If the status of the LP-WUR signal is changed and the UE 20 is in idle mode, the UE 20 establishes an RRC connection using an RRC setup procedure, which includes adding the assigned identifier into either message 3 (step 1 in Figure 10) or in msg 5 (step 3 on in Figure 10). This UE identifier may also be split between these messages, for example.

STEP 4: At the base station (gNB) 30 once the receiver (e.g., LW-WUR) status and UE identifier are received, the base station 30 forwards it to the core network, which associates and saves the received receiver (e.g., LW-WUR) status to a particular device identified by the allocated UE identifier. This may be achieved in such a way, that even if UE identifier or UE 20 is re-located, the association remains.

STEP 5: The core network uses one of any existing or a new message (over NG-AP or in case of LTE or over 51-AP) to inform the base station (gNB) 30 that the connection could be re-leased. Alternatively, a reject message may be used.

STEP 6: The base station (gNB) 30 releases the connection with the UE 20.

-23 -STEP 7: If there are data to be sent to or from this particular device or UE 20, the core network initiates paging including a currently valid S-TMSI and the receiver (LP-WUR) status.

STEP 8: The base station (gNB) 30 initiates paging taking into account of the current UE receiver (e.g., LP-WUR Status).

With the UE 20 in RRC connected mode, the following procedure may be used.

The UE 20 may inform the base station (gNB) 30 about its receiver, e.g., its primary and/or secondary (LP-WUR) status. This might be done using a UE assistance information message, for example. The receiver (secondary or LP-WUR) status may be stored in the base station 30 and associated to UE context once the UE 20 was sent to RRC inactive mode or may be provided to the core network, once the current connection ends (e.g. using a UE context release request).

As used throughout, including in the claims, unless the context indicates otherwise, singular forms of the terms herein are to be construed as including the plural form and vice versa. For instance, unless the context indicates otherwise, a singular reference herein including in the claims, such as "a" or "an" (such as an ion multipole device) means "one or more" (for instance, one or more ion multipole device). Throughout the description and claims of this disclosure, the words "comprise", "including", "having" and "contain" and variations of the words, for example "comprising" and "comprises" or similar, mean "including but not limited to", and are not intended to (and do not) exclude other components. Also, the use of "or" is inclusive, such that the phrase "A or B" is true when "A" is true, "B is true", or both "A" and "B" are true.

The use of any and all examples, or exemplary language ("for instance", "such as", "for example" and like language) provided herein, is intended merely to better illustrate the disclosure and does not indicate a limitation on the scope of the disclosure unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosure.

The terms "first" and "second" may be reversed without changing the scope of the disclosure. That is, an element termed a "first" element may instead be termed a "second" -24 -element and an element termed a "second" element may instead be considered a "first" element.

Any steps described in this specification may be performed in any order or simultaneously unless stated or the context requires otherwise. Moreover, where a step is described as being performed after a step, this does not preclude intervening steps being performed.

It is also to be understood that, for any given component or embodiment described throughout, any of the possible candidates or alternatives listed for that component may generally be used individually or in combination with one another, unless implicitly or explicitly understood or stated otherwise. It will be understood that any list of such candidates or alternatives is merely illustrative, not limiting, unless implicitly or explicitly understood or stated otherwise.

Unless otherwise described, all technical and scientific terms used throughout have a meaning as is commonly understood by one of ordinary skill in the art to which the various embodiments described herein belongs.

As will be appreciated by the skilled person, details of the above embodiment may be varied without departing from the scope of the present invention, as defined by the appended claims.

For example, whilst the use of the method has been described with reference to a UE, other devices may be used. Many device or UEs maybe present in the telecommunications system as well as many base stations or gNBs. The method has been described with reference to paging messages but other messages may be used.

Many combinations, modifications, or alterations to the features of the above embodiments will be readily apparent to the skilled person and are intended to form part of the invention. Any of the features described specifically relating to one embodiment or example may be used in any other embodiment by making the appropriate changes.

Claims

-25 -CLAIMS: 1. A method for managing communications between a user equipment, UE, having a primary receiver and a secondary receiver, and a telecommunications network, the method comprising the steps of: the UE monitoring characteristics of a radio link between the UE and a base station of the telecommunications network; if the characteristics indicate a degradation of the radio link to a predetermined threshold then powering down the secondary receiver; providing information to the telecommunications network indicating a receiver status of the UE; and the telecommunications network ceasing transmissions to the secondary receiver if the receiver status of the UE provided in the information indicates that the secondary receiver is powered down.
2. The method of claim 1 further comprising the steps of: the UE powering up the secondary receiver; the UE providing the telecommunications network with further information indicating the receiver status of the UE; and the telecommunications network resuming transmissions to the secondary receiver if the receiver status of the UE provided in the further information indicates that the secondary receiver is powered up.
3. The method of claim 2, wherein the UE powers up the secondary receiver in response to determining that the characteristics indicate an improvement of the radio link to a second predetermined threshold.
4. The method according to any previous claim, wherein the transmissions to the secondary receiver are transmissions causing the UE to change a power mode of the primary receiver from a second power mode to a first power mode, wherein the primary receiver consumes more power in the first power mode than when in the second power mode.
-26 - 5. The method according to any previous claim, wherein the monitored characteristics of the radio link between the UE and a base station include any one or more of: received signal strength; reference signal received power, RSRP; reference signal received quality, RSRQ; and/or number of repetitions of a message sent to the secondary receiver within a predetermined time period.
6. The method according to any previous claim, wherein the UE is in radio resource control, RRC, idle mode or RRC inactive mode.
7. The method according to any previous claim, wherein the information indicating the status of the secondary receiver provided to the telecommunications network includes an identifier of the UE.
8. The method of claim 7, wherein the identifier of the UE is an inactive radio network temporary identifier, I-RNTI, assigned by a radio access network, RAN.
9. The method of claim 8, wherein the information indicating the receiver status of the UE is transmitted to the telecommunications network within a scheduled uplink physical uplink shared channel, UL PUSCH, transmission.
10. The method of claim 8 or claim 9 further comprising the steps of: the UE moving to a new base station; and the new base station retrieving from the original base station the information indicating that the receiver status of the UE.
11. The method of claim 7, wherein the identifier of the UE is a serving temporary mobile subscriber identity, S-TMSI, assigned by a core network.
12. The method of claim 11, wherein the information indicating the receiver status of the UE is transmitted to the telecommunications network within a radio resource control, RRC, communication between the UE and the base station.
-27 - 13. The method according to claim 11 or claim 12, wherein the step of providing information to the telecommunications network indicating the receiver status of the UE is transmitted by the UE when the UE is in RRC idle mode.
14. The method according to any previous claim further comprising the step of a core network providing the base station with information indicating the receiver status of the UE.
15. The method of claim 14, wherein the core network provides the base station with the information indicating the receiver status of the UE at the same time as paging the UE.
16. The method of claim 14 or claim 15 further comprising the step of the base station issuing a RRC message to the UE causing the UE to release connection with the base station.
17. The method according to any of claims 1 to 12, wherein the step of providing information to the telecommunications network indicating the receiver status of the UE is transmitted by the UE when the UE is in RRC connected mode.
18. The method of claim 17, wherein the receiver status of the UE is transmitted by the UE within a UE assistance information message.
19. The method of claim 17 or claim 18 further comprising the step of the base station storing the receiver status of the UE.
20. The method of claim 19, wherein the base station associates the stored receiver status of the UE with a context of the UE.
21. The method according to any previous claim, wherein the information provided to the telecommunications network indicating the receiver status of the UE comprises any one or more of: a powered up or a powered down status of the primary receiver; and/or a powered up or a powered down status of the secondary receiver.
22. A telecommunications network comprising: one or more base stations; one or more UEs; and -28 -means adapted to perform the method according to any previous claim.