Efficient signal monitoring

Abstract

System and method for managing user equipment, UE, the UE having a primary receiver and a secondary receiver, the method comprising the steps of the UE measuring a signal strength of signals received from a serving base station using the secondary receiver. When the measured signal strength of the signals received from the serving base station falls to a first threshold the secondary receiver causing the primary receiver to switch to a higher power mode from a lower power mode, and the primary receiver of the UE measuring the signal strength of the signals received from a serving base station instead of the secondary receiver.

Description

[0001] Efficient Signal Monitoring

[0002] Field of the Invention

[0003] 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.

[0004] Background of the Invention

[0005] 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.

[0006] 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.

[0007] 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.

[0008] 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).

[0009] When not in connected mode (i.e., idle or inactive modes) the UE can determine whether or not the serving base station can adequately provide services to the UE. The UE does this by making regular signal level measurements. For example, these may be inter-frequency measurements or intra-frequency measurements. When the signal drops below a certain threshold value then the UE can also start to make signal measurements on signals received from neighbouring cells. The accuracy of these measurements is important as they determine how and when the UE commences a cell reselection process. The measurements are made using the primary receiver to maintain accuracy, but this could be improved.

[0010] Therefore, there is required a method and system that overcomes these problems.

[0011] Summary of the Invention

[0012] 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).

[0013] 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 (e.g., 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).

[0014] When signal levels measured by the UE in non-connected mode (e.g., idle or inactive mode) are at a high level (e.g., because the UE is close to the centre of a cell) then the lower accuracy signal (e.g., dB) measurements are sufficient as the signal levels may be well within a range (e.g., above -60dB to -80dB) that does not require the UE to start making measurements from neighbouring cells. This is because it is unlikely that cell or base station reselection will be required. Therefore, the UE can use the secondary (lower power) receiver to make signal level measurements (from the serving cell or base station). This has the benefit of saving power and resources as the main or primary receiver can remain in a lower power or sleep mode. However, when the signal level measured by the secondary receiver falls to or below a first (predetermined or definable) threshold level (e.g., -79dB) then the main receiver can be activated, woken, or otherwise powered up and take over obtaining signal measurements from the secondary receiver.

[0015] At this point, the primary receiver can continue to measure signals from the serving base station. However, should the signals received and measured by the primary (higher power) receiver fall further, i.e., to a second threshold (e.g., -86dB), then the primary receiver can start to measure signals received from a neighbouring base station rather than (or as well as) the serving base station. Initially, the primary receiver can measure the signals from the neighbouring base station in a relaxed mode (i.e., at a sampling interval higher than that of a normal mode). Relaxed mode can use fewer power and processing resources than normal mode. The primary receiver continues to make these measurements in relaxed mode unless the signal measures fall below a third threshold (e.g., -89dB). If this signal level is reached then the measurements of the signal level for the neighbouring base station are recorded in normal mode (i.e., with shorter intervals between measurements than relaxed mode).

[0016] A reselection process (e.g., switching to a new serving base station) can take place whenever reselection criteria are reached. For example, this can occur when the signal levels between the serving base station and any one or more neighbouring base stations are compared and the neighbouring base station signals are higher than the serving base station (or have other higher parameters in comparison) and the signal level of the serving base station is below a particular value or threshold. Optionally, the reselection criteria may start to be checked as soon as the second threshold is reached (i.e., the signal from the serving base station drops to this level).

[0017] Should the measured signal levels move in the opposite direction (e.g., the serving base station level increases above the first or a separate threshold) then the secondary receiver can take over the measurements and the primary receiver can be powered down or put into a low power or sleep mode. The secondary receiver can control whether or not the primary receiver is in the low power or the higher power (active) mode by sending a signal or message to the primary receiver that retains enough power in low power or sleep mode to monitor such signals or messages from the secondary receiver.

[0018] In accordance with a first aspect there is provided a method for managing user equipment, UE, the UE having a primary receiver and a secondary receiver, the method comprising the steps of: the UE measuring a signal strength of signals received from a serving base station using the secondary receiver; and when the measured signal strength of the signals received from the serving base station falls to a first threshold: the secondary receiver causing the primary receiver to switch to a higher power mode from a lower power mode; and the primary receiver of the UE measuring the signal strength of the signals received from a serving base station instead of the secondary receiver. Therefore, fewer resources are used to monitor base station signal levels (when there is a much lower probability that the measurements need to be used to make any operational changes) and higher quality measurements can be made only when necessary. This reduces power usage without compromising usability of the UE.

[0019] When the first threshold is reached then the primary receiver can start making measurements from the serving base station. Optionally, it may simultaneously make signal measurements from a neighbouring base station or only start to do so when the signal drops below a second threshold.

[0020] The method may start with the primary receiver in the lower or low power mode. The lower or low power mode may be a power mode where some electrical power is consumed (e.g., to carry out a minimum of background tasks but not capable or measuring signal levels of received signals). Alternatively, the lower power mode may have the primary receiver completely powered down and consuming no power at all.

[0021] Advantageously, the secondary receiver may have a sensitivity for signal measurement lower than the primary receiver and / or the secondary receiver consumes less power than the primary receiver when making signal measurements. Therefore, this saves power when only lower quality or less critical measurements are required.

[0022] Optionally, the method may further comprise the step of: when the signal strength of the signals from the serving base station measured by the primary receiver falls to a second threshold, the primary receiver measuring a signal strength of signals received from a base station neighbouring the serving base station instead of or as well as measuring the signal strength of signals received form the serving base station. The second threshold is a lower signal strength level than the first threshold. When the signal received from the serving base station falls to a particular level then this can indicate that reselection will be required (but the reselection criteria are not yet met). The second threshold can be set so that when reached it is important to start monitoring signals from one or more neighbouring base stations.

[0023] Optionally, the primary receiver may measure the signal strength from signals from the serving base station and / or the neighbouring base station in a relaxed mode. Relaxed mode may involve longer intervals between measurements than a normal mode or other resource saving measures. Optionally, the primary receiver may also make measurements from the serving base station in relaxed (or normal) mode at the same time.

[0024] Optionally , the method may further comprise the step of: when the signal strength of the signals from the neighbouring base station and / or the serving base station measured by the primary receiver falls to a third threshold, the primary receiver measuring the signal strength of the signals from the neighbouring base station and / or the serving base station in a normal mode instead of the relaxed mode. The third threshold is a lower signal strength than the second threshold. The third threshold can be set when to a signal level indicating that reselection will be required imminently. This may also be indicated by the signal level measured from the neighbouring base station being significantly above that of the serving base station (e.g., a difference greater than 5-1 OdB). Therefore, more regular measurements may be required and more important than saving resources provided by using the relaxed mode. The thresholds may be set and / or varied by a network component.

[0025] Optionally, the method may further comprise the step of: when one or more cell reselection criteria are met, initiating a base station reselection process. This may occur at any signal level that is measured and ensures that an optimal base station acts as the serving base station whilst reducing base station hopping. Preferably, reselection criteria checks commence when the primary receiver starts to monitor signal levels from one or more neighbouring base stations (i.e., after the second threshold is reached).

[0026] Optionally, the method may operate with the UE in a non-connected mode. Therefore, the UE only needs to monitor signal conditions in advance of when a connected mode is required and data and other services can be provided.

[0027] Optionally, the non-connected mode may be idle mode or inactive mode.

[0028] Optionally, the method may further comprise the steps of: when the signal strength of the signals from the serving base station measured by the primary receiver rises above a fourth threshold: the secondary receiver of the UE measuring the signal strength of the signals received from the serving base station instead of the primary receiver; and the primary receiver switching to the lower power mode. The fourth threshold may be the same as the first threshold. However, in order to avoid hysteresis (or oscillations) then the fourth threshold may be the higher than the first threshold (e.g., by around 1 -5dB). Reselection criteria checks may also cease when the signal level from the serving base station rises above the first (or fourth) threshold. Therefore, the method may reverse when the signal increases. This may be extended to the second and third thresholds as well, i.e., the primary receiver stops measuring neighbouring base station signal levels when the signal rises to or slightly above the second threshold and / or the mode changes from normal to relaxed when the signal level measured from the neighbouring base station rises to or just above the third threshold.

[0029] Optionally, the signal measurements may be intra frequency or inter frequency signal strength measurements. Preferably, intra frequency measurements are made.

[0030] Optionally, the first threshold may be between -70dB and -90dB. The second threshold may be between -80dB and -90dB. The third threshold may be between -85dB and -95dB. Other values and threshold levels may be used.

[0031] In accordance with a second aspect there may be provided user equipment, UE, comprising: a primary receiver; a secondary receiver having a lower power consumption than the primary receiver when receiving signals and measuring received signal strength; and one or more processors and one or more storage devices storing instructions that are operable, when executed by the one or more computers, to cause the one or more processors to execute the steps of: measuring, by the secondary receiver, a signal strength of signals received from a serving base station using the secondary receiver; when the measured signal strength of the signals received from the serving base station falls to a first threshold: switching the primary receiver to a higher power mode from a lower power mode; and measuring the signal strength of the signals received from a serving base station using the primary receiver of the UE instead of using the secondary receiver of the UE.

[0032] Optionally, the secondary receiver may be configured to receive a wake up signal from a base station and in response, issue a command to the primary receiver to switch 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 secondary receiver may have at least a dual purpose.

[0033] In accordance with a third aspect there may be provided telecommunications system comprising: the UE, as described above; and one or more base stations (including a serving and one or more neighbouring base stations).

[0034] Optionally, the telecommunications system may be configured to operate with LTE, 5G, and / or 6G technologies. Other technologies may be used and used together.

[0035] In accordance with a third aspect there may be provided a non-transitory computer- readable medium storing software comprising instructions executable by one or more computers which, upon such execution, cause the one or more computers to carry out the methods described above.

[0036] 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.

[0037] 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 (CRM) may be included to store the logic or program instructions. For example, embodiments may include a non-transitory computer-readable medium (CRM) storing software comprising instructions executable by one or more computers which, upon such execution, cause the one or more computers to perform the disclosed methods. Non-transitory CRM may refer to a CRM that stores data for short periods or in the presence of power such as a memory device or Random Access Memory (RAM). For example, a non-transitory computer-readable medium may include storage components, such as, a hard disk (e.g., a magnetic disk, an optical disk, a magneto-optic disk, and / or a solid state disk), a compact disc (CD), a digital versatile disc (DVD), a floppy disk, a cartridge, and / or a magnetic tape. 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.

[0038] It should be noted that any feature described above may be used with any particular aspect or embodiment of the invention.

[0039] Brief description of the Fiaures

[0040] 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:

[0041] Fig. 1 shows a schematic illustration of the timing of signals between a network and user equipment (UE);

[0042] Fig. 2 shows a schematic diagram of a system for initiating communications between a network and the UE;

[0043] Fig. 3 shows a flowchart of a method for managing the UE of Figure 2;

[0044] Fig. 4 shows a flowchart of a further method for managing the UE of Figure 2;

[0045] Fig. 5 shows a flowchart of a further method for managing the UE of Figure 2;

[0046] Fig. 6 shows a graphical illustration of operations carried out by the UE of Figure 2;

[0047] Fig. 7 shows a schematic illustration of a timeline of events carried out by the UE of Figure 2;

[0048] Fig. 8 shows a schematic diagram of events and conditions carried out by the UE of Figure 2; and

[0049] Fig. 9 shows a schematic diagram of system for executing the methods of figures 3, 4 and / or 5;

[0050] 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.

[0051] Detailed description of the preferred embodiments

[0052] 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:

[0053] 1 ) Lower modulation order (OOK, FSK); and

[0054] 2) Smaller amount of data to be transmitted

[0055] 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 . However, both receivers can measure the signal strengths of each different type of signal. In other words, although he secondary receiver is optimised to receive different signals than the primary receiver, it may still be used to monitor and measure other signal types, including those intended for the primary receiver.

[0056] 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.

[0057] For example, the receiver architecture for the secondary receiver may be based on:

[0058] 1 ) RF Envelope detection;

[0059] 2) Heterodyne architecture with Intermediate Frequency envelope detection;

[0060] 3) Homodyne / zero-lntermediate Frequency architecture with baseband envelope detection; and

[0061] 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.

[0062] 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).

[0063] 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 (low power mode) and not be completely shut off.

[0064] 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 may consume approximately 0.015 times the power of the active state of the primary receiver. This may be found in TR 38.869.

[0065] 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. There may be one or more (a group of) neighbouring base stations (not shown in this figure). These neighbouring base stations provide alternatives to the serving base station (30 in this figure) should signal degradation occur.

[0066] 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.

[0067] In Figure 2, the transmission 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. The trigger 25 sent from the secondary receiver 50 to the primary receiver 40 can be sent whether or not the secondary receiver 50 receives the wake up (LP-WUS) signal 55 and the ability to send this trigger is utilised in the following description and enhancements.

[0068] These receiver architectures are aimed to achieve a lower power consumption when compared to the main receiver, at the cost of lower receiving sensitivity. The main or primary receiver 40 sensitivity values can be found on TS 38.101 -1 and can be as low as - 96.8 dBm for the reception of a QPSK signal for n1 with 15 kHz SCS with a 2RX receiver.

[0069] For comparison, the sensitivity values for the secondary receiver 50 may be between -50 to -90 dBm. By having lower receiving sensitivity when compared to a main a receiver, depending on the LP-WUS signal design, the LP-WUR may have coverage performance degradation. With the UE 20 in a non-connected mode (e.g., idle mode) serving cell and target cell measurements are obtained by a receiver of the UE 20. The different sensitivity levels of the primary receiver 40 and the secondary (LP-WUR) receiver 50, may be expected to cause difficulties if secondary receiver 40 is responsible for those measurements and also for reselection process. Therefore, in existing implementations, only the primary receiver 40 is used.

[0070] Figure 3 shows a flowchart of a method 100 of managing one or more UEs each having a primary receiver 40 and a secondary receiver 50. The method 100 starts with the primary receiver in its low power mode (step 110). Low power mode may be an off state (no power consumption) or consuming only enough power to maintain minimum functionality (e.g., monitoring a signal to turn it on, power up, or switch to a higher power mode). The secondary receiver is measuring a signal strength from a serving base station 30 (step 120). At some point in time the signal from the serving base station 30 drops below a first threshold and it is detected at step 130. This may be due to many different reasons, including movement of the UE 20 to a location having lower reception qualities. At step 140, the primary receiver switches from its low power mode to a high power mode where it can receive signals from base stations. This may be triggered by the secondary receiver 50 (trigger 25) or using another message or internal switch. At step 150, the primary receiver starts measuring the signal level from the serving base station 30 instead of (or as well as) the secondary receiver 50. Therefore, Figure 3 shows at a high level the method 100 for operating and managing user equipment.

[0071] Figure 4 shows a flowchart of an enhanced method 100’ for managing user equipment. Similar steps shown in Figure 4 have the same reference numerals as those of Figure 3. However, the method 100’ of Figure 4 includes additional steps, which enhance the method.

[0072] Continuing from step 150, the method 100’ proceeds to a situation where the signal from the serving base station drops below a second threshold at step 160. This may occur because the UE is moving further from the centre of a cell served by the serving base station 30 or for other reasons. Dropping below this second threshold (as measured by the primary receiver of the UE) causes the primary receiver to commence measurements of signal levels from one or more neighbouring base stations. The primary receiver may continue to measure the signal level from the serving base station at the same time or only measure the signal level from the one or more neighbouring base stations. In any case, during step 170 the measurements made by the primary receiver of the neighbouring base station are made in a relaxed mode. Fewer system resources are used during the relaxed mode than when a normal mode of measurements are obtained. For example, intervals between measurements may be longer in the relaxed mode than in the normal mode. In an example implementation, reselection criteria also start to be monitored as soon as the signals from the one or more neighbouring base stations start to be monitored. This is not shown in this simplified flowchart.

[0073] The signal level from the neighbouring base station may drop below a further third threshold at step 180. Again, this may be due to different causes. However, this causes the measurements made by the primary receiver 40 to switch from the relaxed mode to the normal mode at step 190 as this could indicate that a reselection process needs to commence. Again, the primary receiver 40 may simultaneously be measuring signal levels from the serving base station when it is in both relaxed and normal modes. In a separate embodiment, the primary receiver 40 may commence measurements from the serving base station at step 150 in relaxed mode and when those signals drop below a threshold (e.g., the second threshold) then this could cause the mode to switch from relaxed to normal mode (i.e., before any measurements start to be taken of the signals from neighbouring base stations).

[0074] The methods described with reference to Figures 3 and 4 illustrate how the UE 20 manages the process in which the received signal strength measured by the primary and secondary receivers of the UE 20 fall below the first, second and third thresholds and resultants measurements that are taken after this occurs. However, in reality the received signal strength may go up as well as down in certain circumstances. Furthermore, even after the received signal strength, as detected by a receiver, has fallen below a particular threshold then it may increase above that threshold at a later time. Should this occur then the actions taken when the signal strength drops below those thresholds may be reversed when passing back above those thresholds. For example, when the primary receiver 40 has been switched from its low power mode to high power mode and is measuring the signal strength from the serving base station 30 then if the signal strength passes above the first threshold then the primary receiver 40 may switch from high power mode to low power mode and the secondary receiver 50 may take over measuring signal strength from the serving base station 30. This process may repeat. Furthermore, passing below the second threshold and into the step 170 when the primary receiver is measuring signal strength from a neighbouring base station and / or the serving base station in relax mode then should the signal strength received and measured by the primary receiver from the serving base station pass back up above the second threshold, measurement from the neighbouring base station may be paused. However, when the signal strength varies around a particular threshold then the switching process may change repeatedly. To avoid this, there may be a level of hysteresis provided in the thresholds so that there are two thresholds rather than a single threshold. For example, a fourth threshold may be defined just above the first threshold (e.g., 1 to 3 dB difference) for the primary receiver 40 to be switched to low power mode and for the second receiver 40 to resume measurements of the signal level from the serving base station then the signal strength must rise above the first threshold and reach the fourth threshold. This avoids oscillations around a single threshold.

[0075] Figure 5 shows a further enhanced method 200 illustrating how the UE 20 manages such situations with further thresholds defined. Again, similar steps have the same reference numerals as those shown in the previous figures.

[0076] Step 210 shows how the signal received from the serving base station as measured by the secondary receiver 50 is continuously monitored. If it falls below the first threshold, the primary receiver is powered up and takes over measurements (steps 140 and 150). At this stage the second and fourth thresholds are both continuously monitored at steps 230 and 220, respectively. Should the signal strength rise above the fourth threshold then the method returns to step 110 with the primary receiver 40 being switched to low power mode and secondary receiver 50 taking over measurements of the serving base station at step 120. If the signal strength drops below the second threshold, the primary receiver 40 commences measurements of signals received from a neighbouring base station and / or the serving base station in relaxed mode at step 170, as described in the previous figures. Following step 170, both a third threshold and a fifth threshold are monitored at steps 240 and 250, respectively. Should the signal rise above the fifth threshold then the method 200 returns to the primary receiver 40 measuring signals from the serving base station alone at step 150. Should the signal received from the neighbouring base station, as measured in relax mode, drop below the third threshold (step 240) then the primary receiver 40 can switch to measuring the neighbouring base station and / or the serving base station signal in normal mode at step 190. There may also be a sixth threshold (not shown in this figure) above which the primary receiver 40 switches back to measurements in relax mode.

[0077] The UE 20 performs two main types of actions when in idle mode:

[0078] 1 . Start measurements of a target base station. This can include three separate cases:

[0079] • Intra Frequency;

[0080] • Inter Frequency / lnterRAT of higher Prio; and

[0081] • Inter Frequency / lnterRAT of lower Prio.

[0082] 2. The current specification allows the UE 20 not to avoid intra frequency measurements if the serving cell fulfils Srxlev > Sintrasearchp and Squal > S IntraSearchQ- Otherwise, the UE shall perform intra-frequency measurements. However, these may be in relaxed mode or normal mode with measurements taking place less often in relaxed mode.

[0083] Sintrasearchp may be between 0-62 dB, where

[0084] Srxlev is Srxlev = Qrxlevmeas - (Qrxlevmin + Qrxlevminoffset )- Pcompensation - Qoffsettemp

[0085] For simplicity reasons, we can consider: Qrxlevminoffset, Pcompensation, Qoffsettemp being 0. Under these conditions, the UE 20 may start measurements of the target if:

[0086] Srxlev = Qrxlevmeas - Qrxlevmin where Qrxlevmin is between -44 and -140dB.

[0087] As an example:

[0088] The UE 20 may start Intra-Frequency measurements in case SintraSearch is set to 20 dB and Qrxlevmin is by -110 dbm in Qrxlevmeas in dbm-(-110 dbm)>20 dB. The UE 20 fulfils the condition in this example until the base station signal becomes less than or equal to -89 dbm.

[0089] The above thresholds may be sent in different system information messages with NR. Qrxlevmin and Sintrasearchp can be found in SIB2 (NR 38.331). As shown in the following table:

[0090] In LTE, similar information may be be included in other SIBs.

[0091] The UE 20 may start performing normal intra frequency measurements as described in 38.133 chapter 4.2.2.3. This may also depend on several factors such as configured DRX cycle, for example (see tables Table 4.2.2.3-1 of 38.133 chapter).

[0092] As an alternative to the above description, the UE 20 may start relaxed measurements as described in 38.133 chapter 4.2.2.9 and so perform measurements with under relaxed conditions as per table. 4.2.2.9.2-1 and / or Table 4.2.2.9.3-1 using a relaxation factor “k”. In order to apply relaxed measurements, these need to be configured in SIB2, as shown in the following table. Corresponding conditions, described in 38.304 chapter 5.2.4.9, need to be met.

[0093] In general, relaxed measurements should be made when the UE 20 has good coverage and is stationary or moving slowly.

[0094] The UE 20 may perform reselection (of the base station) when the following criteria are met (see 5.2.4.6): Intra-frequency and equal priority inter-frequency Cell Reselection criteria

[0095] The cell-ranking criterion Rs for serving cell and Rn for neighbouring cells is defined by:

[0096] Rs= Q meas,s +Qhyst " QoffSettemp

[0097] Rn=Qmeas,n -Qoffset - Qoffsettemp where: where:

[0098] Qmeas RSRP measurement quantity used in cell reselections.

[0099] Qoffset For intra-frequency: Equals to Qoffsets,n, if Qoffsets,nis valid, otherwise this equals to zero.

[0100] For inter-frequency: Equals to Qoffsets,nplus Qoffsetfrequency, if Qoffsets.n is valid, otherwise this equals to Qoffsetfrequency.

[0101] Qoffsettemp Offset temporarily applied to a cell as specified in TS 38.331 [3].

[0102] If Qoffset and Qoffsettemp is set to 0, the neighbour cell should be at least Qhyst better than the source. Assuming Qhyst is for example 4 dB and the UE 20 starts to measure the neighbour at the source cell level of -89 dBm, it will reselect to other cell if the signal becomes better than -85 dBm.

[0103] The example is illustrated in Figure 6, which show the signal level when reselection takes place (700) and the signal level when intra frequency measurements take place (800).

[0104] As mentioned previously, when measurements are made using the secondary receiver (LP-WUR 50) having a lower receiver sensitivity, then those measurements may not be reliable. However, it has been determined that there are signal levels when such low accuracy readings are sufficient for management of the UE 20 in non-connected modes. For example, when the UE 20 is close to the centre of a cell and received a high signal level then even the low receiver sensitivity available from the secondary receiver 50 is sufficient. Moreover, this provides power efficiency savings without adversely affecting management of the UE 20.

[0105] In an example implementation, the intra-frequency measurements may be performed by the secondary receiver 50 as follows: 1 . The UE (primary receiver 40) would receive over SIB2 (for example) information related to intra frequency measurements to be obtained using the secondary receiver 50. For example, this may be provided as Srxlev>SintraSearch_L_WUR. As long this condition is fulfilled then the primary receiver 40 does not perform serving cell measurements at all and may be powered down or switched to a low power mode. As an example: SintraSearch_L_WUR=30 dB; srxlevmin=-110 dbm. Other values may be used. As long as a signal received from the serving cell, as measured by the secondary receiver 50 (LP-WUR), is better or higher than -79dbm, then no actions are taken in terms of other measurements being required and the primary receiver can remain powered down or in a low power (non-receiving) mode.

[0106] 2. If this first threshold is reached (i.e., the signal drops below this level) and secondary receiver 50 detects that the serving cell is providing a signal is worst then -79 dBm, then it will inform the main receiver to start serving cell signal measurements. The secondary receiver 50 may send a message to the primary receiver to power up or move to a higher power mode so that it can start receiving and making measurements (e.g., using trigger 25).

[0107] 3. Once primary receiver 40 commences measurements, then it can be configured with relaxed measurements initially and after reaching a particular (e.g., second) threshold, then it can start performing normal measurements.

[0108] The process is shown schematically as a timeline in Figure 7. In a further implementation, the inter-frequency measurements may also be performed by the secondary receiver 50.

[0109] For simplicity, the timeline of Figure 7 shows a linear progression of degradation of signals (i.e., the method 100’ of Figure 4). At point 810, the signal received from the serving base station 30 drops below the first threshold (e.g., -79dB). Above the line at - 79dB (in this example) the primary receiver 40 is powered down, off, or in its low power mode and the secondary receiver (LP-WUR) 50 performs serving cell signal power measurements. Below the line at -79dB (in this example) the primary receiver 40 is powered up, on, or in its higher power mode and the secondary receiver (LP-WUR) 50 may be powered down. The primary or main receiver 40 is switched on. At point 820 the signal drops below the second threshold (e.g., -85dB) and relaxed measurements (of signals from the serving and / or neighbouring base stations) are used. When the signal drops below the third threshold at point 830 (e.g., -89dB in this example) then measurements are obtained (from the primary receiver 40) in normal mode. In this example implementation (as well as the other described variants), a reselection process (determining at the UE 20 whether or not to move to a different base station and / or use different cellular technology) can occur whenever reselection criteria are met (e.g., if the signal measured from the neighbouring or target base station is greater than -85dB and / or there is sufficient difference in signal levels). This can take place at any time or after the signal measured from either or both serving and / or neighbour base station drops below the second threshold (show by the dotted and then solid horizontal line in Figure 7). Figure 8 show graphically these events in the form of concentric event circles.

[0110] The secondary receiver 50 is a simplified receiver with a restricted number of architectural receiver components, consuming less energy compared to the main receiver at the expense of sensitivity. The examples provided above describe intra frequency measurements. However, the same principals may apply to inter frequency / inter RAT cases with lower / higher priorities, where particular thresholds might be different compared with the intra frequency examples and may be distributed in other SIBs.

[0111] If the secondary receiver 50 is not OFDM capable, then it may measure other signals (from either the serving or neighbouring base stations), which might be measured using different but corresponding technology.

[0112] Any of the described methods may be executed by a computer system. As shown in Figure 9, the computer system 300 includes a number of components including communication interfaces 320, system circuitry 330, input / output (I / O) circuitry 340, display circuitry and interfaces 350, and a datastore 370. The system circuitry 320 can include one or more processors or CPUs 380 and memory 390. The system circuitry 330 may include any combination of hardware, software, firmware, and / or other circuitry. The system circuitry 330 may be implemented, with one or more systems on a chip (SoC), application specific integrated circuits (ASIC), microprocessors, and / or analog and digital circuits.

[0113] The display circuitry may provide one or more graphical user interfaces (GUIs) 360 and the I / O interface circuitry 340 may include touch sensitive or non-touch displays, sound, voice or other recognition inputs, buttons, switches, speakers, sounders, and other user interface elements. The I / O interface circuitry 340 may include microphones, cameras, headset and microphone input / output connectors, Universal Serial Bus (USB) connectors, and SD or other memory card sockets. The I / O interface circuitry 340 may further include data media interfaces (e.g., a CD-ROM or DVD drive) and other bus and display interfaces.

[0114] The memory 390 may include volatile (RAM) or non-volatile memory (e.g., ROM or Flash memory). The memory may store the operating system 392 of the computer system 300, applications or software 394, dynamic data 396, and / or static data 398. The datastore or data source 370 may include one or more databases 372, 374 and / or a file store or file system, for example.

[0115] The method and system may be implemented in hardware, software, or a combination of hardware and software. The method and system may be implemented either as a server comprising a single computer system or as a distributed network of servers connected across a network. Any kind of computer system or other electronic apparatus may be adapted to carry out the described methods.

[0116] 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.

[0117] 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.

[0118] 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” element and an element termed a “second” element may instead be considered a “first” element.

[0119] 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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.

[0124] The signals that are measured by either or both of the primary and secondary receivers may include: frequency shift keying (FSK), on / off keying (OOK), and / or orthogonal frequency division multiplexing (OFDM) signals. Whilst the examples provided above relate to telecommunications systems and UEs, the concept may be applied to Wi-Fi and Bluetooth systems and receives with similar benefits.

[0125] 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

CLAIMS:1 . A method for managing user equipment, UE, the UE having a primary receiver and a secondary receiver, the method comprising the steps of: the UE measuring a signal strength of signals received from a serving base station using the secondary receiver; and when the measured signal strength of the signals received from the serving base station falls to a first threshold: the secondary receiver causing the primary receiver to switch to a higher power mode from a lower power mode; and the primary receiver of the UE measuring the signal strength of the signals received from a serving base station instead of the secondary receiver.

2. The method of claim 1 , wherein the secondary receiver has a sensitivity for signal measurement lower than the primary receiver and / or the secondary receiver consumes less power than the primary receiver when making signal measurements.

3. The method of claim 1 or claim 2, further comprising the step of: when the signal strength of the signals from the serving base station measured by the primary receiver falls to a second threshold, the primary receiver measuring a signal strength of signals received from a base station neighbouring the serving base station instead of or as well as measuring the signal strength of signals received form the serving base station.

4. The method of claim 3, wherein the primary receiver measures the signal strength from signals from the serving base station and / or the neighbouring base station in a relaxed mode.

5. The method of claim 4 further comprising the step of: when the signal strength of the signals from the neighbouring base station and / or the serving base station measured by the primary receiver falls to a third threshold, the primary receiver measuring the signal strength of the signals from the neighbouring base station and / or the serving base station in a normal mode instead of the relaxed mode.

6. The method according to any previous claim further comprising the step of: when one or more cell reselection criteria are met, initiating a base station reselection process.

7. The method according to any previous claim, wherein the method operates with the UE in a non-connected mode.

8. The method of claim 7, wherein the non-connected mode is idle mode or inactive mode.

9. The method according to any previous claim further comprising the steps of: when the signal strength of the signals from the serving base station measured by the primary receiver rises above a fourth threshold: the secondary receiver of the UE measuring the signal strength of the signals received from the serving base station instead of the primary receiver; and the primary receiver switching to the lower power mode.

10. The method according to any previous claim, wherein the signal measurements are intra frequency or inter frequency signal strength measurements.11 . User equipment, UE, comprising: a primary receiver; a secondary receiver having a lower power consumption than the primary receiver when receiving signals and measuring received signal strength; and one or more processors and one or more storage devices storing instructions that are operable, when executed by the one or more computers, to cause the one or more processors to execute the steps of: measuring, by the secondary receiver, a signal strength of signals received from a serving base station using the secondary receiver; when the measured signal strength of the signals received from the serving base station falls to a first threshold: switching the primary receiver to a higher power mode from a lower power mode; andmeasuring the signal strength of the signals received from a serving base station using the primary receiver of the UE instead of using the secondary receiver of the UE.

12. The UE of claim 11 , wherein the secondary receiver is configured to receive a wake up signal from a base station and in response, issue a command to the primary receiver to switch 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.

13. A telecommunications system comprising: the UE of claim 11 or claim 12; and one or more base stations.

14. The telecommunications system of claim 13 configured to operate with LTE, 5G, and / or 6G technologies.

15. A non-transitory computer-readable medium storing software comprising instructions executable by one or more computers which, upon such execution, cause the one or more computers to carry out the method according to any of claims 1 to 10.

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