GB2605214A

GB2605214A - Paging

Info

Publication number: GB2605214A
Application number: GB2111248.7A
Authority: GB
Inventors: Schober Karol; Nissilä Mauri; Korhonen Jouni
Original assignee: Nordic Semiconductor ASA
Current assignee: Nordic Semiconductor ASA
Priority date: 2021-08-04
Filing date: 2021-08-04
Publication date: 2022-09-28
Anticipated expiration: 2041-08-04
Also published as: GB202111248D0; GB2605214B

Abstract

A radio transmitter device, such as a gNB in a 5G network, transmits tracking reference signals (TRS) and a paging frame to a receiver device (user equipment). If the receiver device supports the modified paging mode of the invention, the paging frame is sent at a time determined by a paging frame number n+m, where n is the frame number of a frame which includes a TRS, and m is determined by an operational condition. The operational condition may be the remaining battery life of the receiver device, the reported signal strength, coverage enhancement level or a priority level. The receiver devices monitor the TRS whilst in idle mode. The modified paging mode saves power by allowing the receiver device to spend more time in a deep sleep mode.

Description

Intellectual Property Office Application No G1321112487 RTM Date:13 January 2022 The following terms are registered trade marks and should be read as such wherever they occur in this document: 3 GP P LIE GSM Intellectual Property Office is an operating name of the Patent Office www.gov.uk/ipo Paging

Technical Field

The present invention relates to paging in a radio communications system, particularly though not exclusively a cellular communications system, such as an 3GPP R17 'NR' system, that may provide improved power consumption for receivers in such a system.

Background to the Invention

Throughout the course of the past few decades, the extent and technical capabilities of cellular-based radio communication systems have expanded dramatically. A number of different cellular-based networks have been developed over the years, including the Global System for Mobile Communications (GSM), General Packet Radio Services (GPRS), Enhanced Data rates for GSM Evolution (EDGE), and Universal Mobile Telecommunications System (UMTS), where GSM, GPRS, and EDGE are often referred to as second generation (or "2G") networks and UMTS is referred to as a third generation (or "3G") network.

The Long Term Evolution (LTE) network, a fourth generation (or "4G") network standard specified by the 3rd Generation Partnership Project (3GPP), gained popularity due to its relatively high uplink and downlink speeds and larger network capacity compared to earlier 2G and 3G networks.

More recently, 3GPP have published fifth generation (or "5G") network standards.

At the time of filing, the most recent release of the 5G standard is Release 16 (R16), and work on Release 17 (R17) is currently underway. In general, the radio technology is referred to as 'New Radio' (NR).

From a communications perspective, certain standards from 4G onwards use orthogonal frequency division multiple access (OFDMA) as the basis for allocating network resources, at least in the downlink. This allows the available bandwidth between to be shared between user equipment (UE) that accesses the network in a given cell, provided by a base station, referred to in NR as a 'Next Generation NodeB' or simply cgNB'. OFDMA is a multi-user variant of orthogonal division multiplexing (OFDM), a multiplexing scheme in which the total bandwidth is divided into a number of non-overlapping sub-bands, each having its own sub-carrier frequency. In OFDM, unlike other frequency division multiplexing (FDM) schemes, each of these sub-carriers are orthogonal to one another such that cross-talk between sub-bands is ideally eliminated and removing the need for inter-carrier guard bands. In the uplink, NR supports cyclic prefix OFDMA (CP-OFDMA).

Those skilled in the art will appreciate that the user equipment (UE) may use Discontinuous Reception (DRX) in the 'RRC_IDLE' and RRC_INACTIVE' states in order to reduce power consumption, where 'RRC' stands for 'radio resource control'. The UE monitors one paging occasion (PO) per DRX cycle. It will be appreciated that a PO is a set of physical downlink control channel (PDCCH) monitoring occasions and can consist of multiple time slots (e.g. subframe or OFDM symbol) in which a paging downlink control indicator (DCI) can be sent (as specified in technical specification TS 38.213). One Paging Frame (PF) is one Radio Frame and may contain one or multiple PO(s) or the starting point of a PO.

In multi-beam operations, the UE assumes that the same paging message is repeated in all transmitted beams and thus the selection of the beam(s) for the reception of the paging message is up to UE implementation. A UE may follow one or more beams -generally the best beam(s) -when camping on an NR cell. Transmitted beams are those beams corresponding to transmitted synchronization signal blocks (SSBs), i.e. those SSBs indicated in the parameter (ssb-PositionsInBurst that are quasi-co-location (QCL) sources for the beams served by the gNB.

The UE initiates the RRC Connection Resume procedure upon receiving radio access network (RAN) initiated paging. If the UE receives a core network (CN) initiated paging when the UE is operating in the RRC_INACTIVE state, the UE moves to the RRC IDLE state and informs the Non-Access-Stratum (NAS).

The PF and PO for paging are determined by the following equations, where the subframe number (SFN) for the PF (PFR15) is determined by Equation 1: 3 - (SFN + ffset)mod T = (T div N)* (UErnmod N) Equation 1: Subframe number (SFN) for the PF (PFRis) The index (is) that indicates the index of the PO in PF is determined by Equation 2 below: is = floor (UE1DIN)mod Ns Equation 2: The index (is) that indicates the index of the PO in PF where * T is the DRX cycle of the UE; where T is determined by the shortest of the UE specific DRX value if configured by RRC or upper layers, and a default DRX value broadcast in system information. If UE specific DRX is not configured by RRC or by upper layers, the default value is applied.

* N is the number of total paging frames in T * Ns is the number of paging occasions for a PF * P Foffset is the offset used for PF determination * UEID is the 5G-S-TMSI (5G S-Temporary Mobile Subscriber Identity) mod 2024 The parameters Ns, nAndPagingFrameOffset, and the length of default DRX Cycle are signalled in the first system information block (SIB1). The values of N and PFoffset are derived from the parameter nAndPagingFrameOffset as defined in TS 38.331, incorporated herein by reference. If the UE has no 5G-S-TMSI, for instance when the UE has not yet registered onto the network, the UE shall use as default identity UE'm = 0 in the PF and is formulas above.

The 3GPP 5G standard introduces a tracking reference signal (TRS) for the 5G downlink and uplink which is used by the UE for phase tracking purposes. These TRS may be sent to the UE when in the 'IDLE' state, where these are referred to as 'Idle TRS'. In RAN1#105e, it has been agreed that Idle TRS are configured to be sent with periodicity selected from the options {10, 20, 40, 80} ms. Depending on the sub-carrier spacing (SCS) in use, this may correspond to 20, 40, 80 and 160 4 -slots of 30kHz SCS. Those skilled in the art will appreciate that, in general, this SCS is typically the one indicated or used for the ControlResourceSet (CORESET) as indicated by the master information block (MI B). A further parameter frequencyDomainAllocafion with an applicable value selected from the options {0, 1, 2, 3} indicates the offset of the first resource element (RE) to RE#0 in a resource block (RB).

The Applicant has appreciated, however, that the shorter the periodicity of the Idle TRS (and particularly with the shorter options 10 ms and 20 ms), the more system overhead is caused to the downlink (DL), because the serving gNB serves RRC connected UEs in addition to any idle camping UEs for which the TRS are intended. Therefore, in general, the gNB would prefer to transmit TRS with the longer periodicity options such as 40 ms or 80 ms. Idle TRS bursts (i.e. a set of TRS with different QCL property) become a significant overhead if the gNB operates several beams in the cell because the gNB must transmit one TRS resource per beam in NR.

Simultaneously, the Applicant has appreciated that the UE achieves better power saving gains if the TRS are transmitted in one frame before the actual PO, and particularly between the SSB and the PO. If the paging early indication (PEI) indicates that the UE should wake-up for a PO, and if TRS does not fall between SSB and PO, the UE must wake-up one or more SSB(s) earlier than is strictly necessary, which causes unnecessary power consumption. Typically, TRS would be transmitted by gNB once every 40 ms (for connected mode UEs), while the SSB would be transmitted once every 20 ms, i.e. the default periodicity for SSB burst.

Thus the Applicant has appreciated that it would be advantageous to have an arrangement in which UEs could make better power savings without increasing the system overhead in DL.

Summary of the Invention

When viewed from a first aspect, embodiments of the present invention provide a radio transmitter device configured to communicate with a plurality of radio receiver

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devices, wherein one or more of said radio receiver devices is configured to support a modified paging mode, wherein said radio transmitter device is configured to: transmit a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; transmit a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; determine a first paging frame number for a paging occasion; and determine a second paging frame number n+m when the selected radio receiver device is configured to support the modified paging mode, wherein: n is a frame number of the first frame after or before the first paging frame number that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; and wherein said radio transmitter device is further configured to: transmit the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the second paging frame number when the selected radio receiver device is configured to support the modified paging mode; and transmit the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the first paging frame number when the selected radio receiver device is not configured to support the modified paging mode.

The first aspect of the invention extends to a method of operating a radio transmitter device configured to transmit radio signals to a plurality of radio receiver devices, wherein one or more of said radio receiver devices is configured to support a modified paging mode, the method comprising: transmitting a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; transmitting a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; determining a first paging frame number for a paging occasion; determining a second paging frame number n+m when the selected radio receiver device is configured to support the modified paging mode, wherein: 6 -n is a frame number of the first frame after or before the first paging frame number that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; the method further comprising: transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the second paging frame number when the selected radio receiver device is configured to support the modified paging mode; and transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the first paging frame number when the selected radio receiver device is not configured to support the modified paging mode.

The first aspect also extends to a non-transitory computer-readable medium comprising instructions that, when executed by a processor, cause the processor to carry out a method of operating a radio transmitter device configured to transmit radio signals to a plurality of radio receiver devices, wherein one or more of said radio receiver devices is configured to support a modified paging mode, the method comprising: transmitting a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; transmitting a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; determining a first paging frame number for a paging occasion; determining a second paging frame number n+m when the selected radio receiver device is configured to support the modified paging mode, wherein: n is a frame number of the first frame after or before the first paging frame number that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; the method further comprising: transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the second paging 7 -frame number when the selected radio receiver device is configured to support the modified paging mode; and transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the first paging frame number when the selected radio receiver device is not configured to support the modified paging mode.

The first aspect also extends to a computer software product comprising instructions that, when executed by a processor, cause the processor to carry out a method of operating a radio transmitter device configured to transmit radio signals to a plurality of radio receiver devices, wherein one or more of said radio receiver devices is configured to support a modified paging mode, the method comprising: transmitting a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; transmitting a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; determining a first paging frame number for a paging occasion; determining a second paging frame number n+m when the selected radio receiver device is configured to support the modified paging mode, wherein: n is a frame number of the first frame after or before the first paging frame number that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; the method further comprising: transmitting the paging frame comprising the paging occasion to the radio receiver device at a time determined by the second paging frame number when the selected radio receiver device is configured to support the modified paging mode; and transmitting the paging frame comprising the paging occasion to the radio receiver device at a time determined by the first paging frame number when the selected radio receiver device is not configured to support the modified paging mode.

Thus it will be appreciated that embodiments of the present invention provide an improved arrangement in which, when supported by the appropriate receiver, the 8 -paging occasion is 'shifted' to a time after a TRS following or preceding the first page frame number, i.e. to a time following either the next TRS or the previous TRS respectively. When a given receiver supports the modified paging mode, a paging occasion for that receiver may be transmitted at a time earlier or later than it would otherwise have been under legacy approaches (e.g. 3GPP Release 15). When the receiver does not support the modified paging mode, the paging occasion is sent at the original time, such that the transmitter is backwards-compatible with existing receivers that do not support this mode.

It will be appreciated that the timing of the paging occasion can therefore be advanced or delayed, based on the timing of the TRS, as appropriate. In some embodiments, n is a frame number of the first frame after the first paging frame number that will include a tracking reference signal as determined by the periodicity and the offset. In alternative embodiments, n is a frame number of the first frame before the first paging frame number that will include a tracking reference signal as determined by the periodicity and the offset. In other words, embodiments are envisaged in which the transmitter only delays paging occasions and/or in which the transmitter only advances paging occasions. However, in other embodiments, the transmitter is able to delay or advance a given paging occasion as appropriate.

It will be appreciated that the transmitter may delay and/or advance paging occasions for different ones of the plurality of radio receiver devices (that support the modified paging mode) by different degrees. The transmitter may advance paging occasions for some radio receiver devices and delay paging occasions for some other radio receiver devices, if appropriate.

The degree of time shifting (i.e. modification of the paging timing) is dependent on two factors, n and m, as outlined below. It will be appreciated that as these relate to frame numbers, n and m are both positive integers.

The first of these, n, is an absolute value -specifically a frame number -that is determined by the periodicity and offset of the TRS. The periodicity and offset of the TRS determine the schedule of the TRS, and so with knowledge of these, it can be determined when the next or previous TRS is scheduled for, following or preceding the 'original' paging occasion timing (i.e. the first paging frame number) before performing the shift in paging timing. 9 -

The second factor, m, may provide an offset from that frame (i.e. as defined by the first factor n) containing the TRS, based on the operational condition. As outlined below, there are a number of different operational conditions on which this factor m may be based. If m = 1, then the paging occasion will be delayed until the frame having frame number n + 1. Similarly, if m = 3, the paging occasion will be delayed until the frame having frame number n + 3.

As consequence, receivers (e.g. UEs) having a nominal paging frame preceding the TRS (i.e. having a first paging frame number prior to the TRS) may now have all of their paging in a single frame. This may cause a drawback due to increasing the size of a group having paging in that single frame. However, the Applicant has appreciated that this potential drawback may be alleviated by means of sub-grouping, where a paging early indicator (PEI) may indicate presence of paging for a sub-group of a paging group. This may reduce the groups to be paged and facilitate power saving. It will be appreciated that 3GPP R17 UEs may support such sub-grouping.

In a particular set of such embodiments, the radio transmitter device is further configured to: transmit the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the second paging frame number only when the selected radio receiver device is further configured to support sub-grouping; and transmit the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the first paging frame number when the selected radio receiver device is not configured to support sub-grouping. In other words, the radio transmitter device (e.g. gNB) may, at least in some embodiments, be arranged to use the modified paging mode only with receivers (e.g. UEs) that support both the modified paging mode and sub-grouping. It will be appreciated by those skilled in the art that the term 'sub-grouping' means paging being directed to only a subset of receivers within a larger paging group to which the selected radio receiver device belongs.

-10 -In some embodiments, the plurality of radio receiver devices are configured to monitor said tracking reference signals when operating in an idle mode.

The second factor m may be based on operational conditions reported by the radio receiver such as its battery life. For example, a receiver reporting low battery life may get m = 1, while receivers with high battery life may get m = 3. These conditions may be reported using UE assistance' techniques, known in the art per se. Thus, in some embodiments, the operational condition comprises a parameter reported by the selected radio receiver device. In some such embodiments, the operational condition comprises a reported battery life of the selected radio receiver device. One or more, and potentially all, of the plurality of radio receiver devices may be configured to report operational condition(s) such as its respective battery life.

Additionally or alternatively, the second factor m may be based on a received signal strength at the selected radio receiver device. For example, a radio receiver device (e.g. a UE) may report a power of a received reference signal (e.g. a Reference Signal Received Power or 'RSRP' metric) to the radio transmitter device, where this is then used as an or the operational condition of which m is based. This reference signal may be transmitted by the radio transmitter device. Another parameter that may additionally or alternatively be used as an or the operational condition is a coverage enhancement level. Using the reported power of a received reference signal and/or the indicated coverage enhancement level to determine m may allow the transmitter to compensate for power consumption differences between radio receivers at the centre of a cell served by the transmitter and radio receiver devices operating at the edge of that cell. It will be appreciated that receivers operated at the cell edge generally have a larger power consumption due to their increased UL power requirements and typically requiring more repetitions in the DL.

The second factor m may, additionally or alternatively, be based on a location of the selected radio receiver device. This location may be determined by the radio transmitter device or may be reported by the selected radio receiver device. The selected radio receiver device may determine its location using any suitable technique known in the art per se such as using a global navigation satellite system (GNSS) like the Global Positioning System (GPS), Galileo, BeiDou Navigation Satellite System (BDS), or Global Navigation Satellite System (GLONASS).

The second factor m could also be based on a predetermined pattern such that m varies according to said predetermined pattern from one paging occasion to the next, i.e. between paging cycles. This may advantageously increase fairness among different UE groups. Alternatively, the value for m may vary randomly (or pseudorandomly) which may similarly provide for fairness across the UEs.

The second factor m could also be based on a priority level. This priority level may, for example, be derived from subscription data (e.g. UE subscription data) or an explicit request by a radio receiver device. These may, for example, be determined during a network attach procedure. The priority levels may be predetermined or may be variable, e.g. in response to subscription data or a command.

Thus the operational condition may comprise one or more of: a battery life of the selected radio receiver device; a received signal strength at the selected radio receiver device; a coverage enhancement level; a value determined by a predetermined pattern; a random (or pseudorandom) value; and/or a priority level.

It will be appreciated that the radio transmitter device may determine m using one of these options, or may utilise multiple of these options when determining m. For example, the radio transmitter may assess both a UE's battery life and its reported RSRP when deciding what value is appropriate for m when sending paging occasions for that UE.

The first paging frame number may be determined based on a periodic function. In other words, the 'nominal' timing for the paging occasion (i.e. the timing used when the radio receiver device does not support the modified paging mode) may be periodic. This first paging frame number may be determined in accordance with a manner known in the art per se, i.e. in accordance with existing standards. In some embodiments, the first paging number may be determined in accordance with Equations 1 and 2 as outlined previously.

While the principles of the present invention may readily apply to a number of different radio communication technologies, in at least some embodiments the radio -12 -communication system operates in accordance with a cellular wireless communication protocol, and in preferred embodiments is a 5G communication system. As such, the radio transmitter device may comprise a gNB, and one or more of the radio receiver devices may comprise NR UEs.

The first aspect of the invention extends to a radio communication system comprising the radio transmitter device and the plurality of radio devices.

Thus, when viewed from a second aspect, embodiments of the present invention provide a radio communication system comprising a radio transmitter device and a plurality of radio receiver devices, wherein one or more of said radio receiver devices is configured to support a modified paging mode, said radio communication system being arranged such that: the radio transmitter device is configured to transmit a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; the radio transmitter device is configured to transmit a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; the radio transmitter device is configured to determine a first paging frame number for a paging occasion; the radio transmitter device is configured to determine a second paging frame number n+m when the selected radio receiver device is configured to support the modified paging mode, wherein: n is a frame number of the first frame after or before the first paging frame number that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; wherein the radio transmitter device is further configured to: transmit the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the second paging frame number when the selected radio receiver device is configured to support the modified paging mode; and transmit the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the first paging frame -13 -number when the selected radio receiver device is not configured to support the modified paging mode.

The second aspect of the invention extends to a method of operating a radio communication system comprising a radio transmitter device and a plurality of radio receiver devices, wherein one or more of said radio receiver devices is configured to support a modified paging mode, the method comprising: the radio transmitter device transmitting a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; the radio transmitter device transmitting a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; the radio transmitter device determining a first paging frame number for a paging occasion; the radio transmitter device determining a second paging frame number n+m when the selected radio receiver device is configured to support the modified paging mode, wherein: n is a frame number of the first frame after or before the first paging frame number that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; the method further comprising: the radio transmitter device transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the second paging frame number when the selected radio receiver device is configured to support the modified paging mode; and the radio transmitter device transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the first paging frame number when the selected radio receiver device is not configured to support the modified paging mode.

The second aspect also extends to a non-transitory computer-readable medium comprising instructions that, when executed by a processor, cause the processor to carry out a method of operating a radio communication system comprising a radio -14 -transmitter device and a plurality of radio receiver devices, wherein one or more of said radio receiver devices is configured to support a modified paging mode, the method comprising: the radio transmitter device transmitting a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; the radio transmitter device transmitting a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; the radio transmitter device determining a first paging frame number for a paging occasion the radio transmitter device determining a second paging frame number n+m when the selected radio receiver device is configured to support the modified paging mode, wherein: n is a frame number of the first frame after or before the first paging frame number that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; the method further comprising: the radio transmitter device transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the second paging frame number when the selected radio receiver device is configured to support the modified paging mode; and the radio transmitter device transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the first paging frame number when the selected radio receiver device is not configured to support the modified paging mode.

The second aspect also extends to a computer software product comprising instructions that, when executed by a processor, cause the processor to carry out a method of operating a radio communication system comprising a radio transmitter device and a plurality of radio receiver devices, wherein one or more of said radio receiver devices is configured to support a modified paging mode, the method comprising: -15 -the radio transmitter device transmitting a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; the radio transmitter device transmitting a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; the radio transmitter device determining a first paging frame number for a paging occasion the radio transmitter device determining a second paging frame number n+m when the selected radio receiver device is configured to support the modified paging mode, wherein: n is a frame number of the first frame after or before the first paging frame number that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; the method further comprising: the radio transmitter device transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the second paging frame number when the selected radio receiver device is configured to support the modified paging mode; and the radio transmitter device transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the first paging frame number when the selected radio receiver device is not configured to support the modified paging mode.

When viewed from a third aspect, embodiments of the present invention provide a radio receiver device configured to received radio signals from a radio transmitter device, said radio receiver device being configured to: support a modified paging mode; receive a tracking reference signal from the radio transmitter device, said tracking reference signal having a periodicity and an offset; and receive a paging frame comprising a paging occasion from the radio transmitter device at a time determined by a modified paging frame number n+m, wherein: -16 -n is a frame number of a frame that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition.

The third aspect of the invention extends to a method of operating a radio receiver device configured to received radio signals from a radio transmitter device, said radio receiver device being further configured to support a modified paging mode, the method comprising: receiving a tracking reference signal from the radio transmitter device, said tracking reference signal having a periodicity and an offset; and receiving a paging frame comprising a paging occasion from the radio transmitter device at a time determined by a modified paging frame number n+m, wherein: n is a frame number of a frame that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition.

The third aspect also extends to a non-transitory computer-readable medium comprising instructions that, when executed by a processor, cause the processor to carry out a method of operating a radio receiver device configured to received radio signals from a radio transmitter device, said radio receiver device being further configured to support a modified paging mode, the method comprising: receiving a tracking reference signal from the radio transmitter device, said tracking reference signal having a periodicity and an offset; and receiving a paging frame comprising a paging occasion from the radio transmitter device at a time determined by a modified paging frame number n+m, wherein: n is a frame number of a frame that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition.

The third aspect also extends to a computer software product comprising instructions that, when executed by a processor, cause the processor to carry out a method of operating a radio receiver device configured to received radio signals -17 -from a radio transmitter device, said radio receiver device being further configured to support a modified paging mode, the method comprising: receiving a tracking reference signal from the radio transmitter device, said tracking reference signal having a periodicity and an offset; and receiving a paging frame comprising a paging occasion from the radio transmitter device at a time determined by a modified paging frame number n+m, wherein: n is a frame number of a frame that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition.

Embodiments are envisaged in which legacy mode receivers are not supported, and such that all of the radio receiver devices with which the radio transmitter device communicates support the advancing and/or delaying of paging occasions.

Thus, when viewed from a fourth aspect, embodiments of the present invention provide a radio transmitter device configured to communicate with a plurality of radio receiver devices, wherein said radio transmitter device is configured to: transmit a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; transmit a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; determine a paging frame number n+m, wherein: n is a frame number of a frame that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; and wherein said radio transmitter device is further configured to transmit the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the paging frame number.

The fourth aspect of the invention extends to a method of operating a radio transmitter device configured to transmit radio signals to a plurality of radio receiver devices, the method comprising: transmitting a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; -18 -transmitting a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; determining a paging frame number n+m, wherein: n is a frame number of a frame that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; the method further comprising transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the paging frame number.

The fourth aspect also extends to a non-transitory computer-readable medium comprising instructions that, when executed by a processor, cause the processor to carry out a method of operating a radio transmitter device configured to transmit radio signals to a plurality of radio receiver devices, the method comprising: transmitting a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; transmitting a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; determining a paging frame number n+m, wherein: n is a frame number of a frame that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; the method further comprising transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the paging frame number.

The first aspect also extends to a computer software product comprising instructions that, when executed by a processor, cause the processor to carry out a method of operating a radio transmitter device configured to transmit radio signals to a plurality of radio receiver devices, the method comprising: transmitting a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; transmitting a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; determining a paging frame number n+m, wherein: -19 -n is a frame number of a frame that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; the method further comprising transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the paging frame number.

When viewed from a fifth aspect, embodiments of the present invention provide a radio communication system comprising a radio transmitter device and a plurality of radio receiver devices, said radio communication system being arranged such that: the radio transmitter device is configured to transmit a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; the radio transmitter device is configured to transmit a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; the radio transmitter device is configured to determine a paging frame number n+m, wherein: n is a frame number of a frame that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; wherein the radio transmitter device is further configured to transmit the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the paging frame number.

The fifth aspect of the invention extends to a method of operating a radio communication system comprising a radio transmitter device and a plurality of radio receiver devices, the method comprising: the radio transmitter device transmitting a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; the radio transmitter device transmitting a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; -20 -the radio transmitter device determining a paging frame number n+m, wherein: n is a frame number of a frame that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; the method further comprising: the radio transmitter device transmitting the paging frame comprising the paging occasion to the radio receiver device at a time determined by the paging frame number.

The fifth aspect also extends to a non-transitory computer-readable medium comprising instructions that, when executed by a processor, cause the processor to carry out a method of operating a radio communication system comprising a radio transmitter device and a plurality of radio receiver devices, the method comprising: the radio transmitter device transmitting a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; the radio transmitter device transmitting a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; the radio transmitter device determining a paging frame number n+m, wherein: n is a frame number of a frame that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; the method further comprising: the radio transmitter device transmitting the paging frame comprising the paging occasion to the radio receiver device at a time determined by the paging frame number.

The fifth aspect also extends to a computer software product comprising instructions that, when executed by a processor, cause the processor to carry out a method of operating a radio communication system comprising a radio transmitter device and a plurality of radio receiver devices, the method comprising -21 -the radio transmitter device transmitting a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; the radio transmitter device transmitting a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; the radio transmitter device determining a paging frame number n+m, wherein: n is a frame number of a frame that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; the method further comprising: the radio transmitter device transmitting the paging frame comprising the paging occasion to the radio receiver device at a time determined by the paging frame number.

Thus, in accordance with the fourth and fifth aspects of the invention, the radio transmitter device may make a determination as to when the paging occasion should be sent based on the periodicity and offset of the TRS (which sets n, the 'starting point' for the frame in which the paging occasion will be sent) and the operational condition (which sets m, the offset to the frame as determined by n) without reference to a legacy paging occasion frame number.

The optional features described in relation to embodiments of any of the foregoing aspects of the invention apply equally to all of the other aspects of the invention, as appropriate. These optional features may be included in any such aspect, in any combination or permutation.

Brief Description of Drawings

Certain embodiments of the invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings in which: Fig. 1 is a block diagram of a radio communications system in accordance with an embodiment of the present invention; -22 -Fig. 2 is a flow chart outlining operation of the system of Fig. 1; Fig. 3 is a block diagram illustrating a comparison of the power consumption associated with paging in a prior art communication system and that of a communication system in accordance with an embodiment of the present invention where timing of a paging occasion is advanced; and Fig. 4 is a block diagram illustrating operation of a communication system in accordance with an embodiment of the present invention where timing of a paging occasion is delayed.

Detailed Description

Fig. 1 is a block diagram of a radio communications system 200 in accordance with an embodiment of the present invention. Here, a gNB 202 is configured to communicate with a number of UEs 204, 206, 208, 210, and 212. Three of these 204, 206, 208 are R17 UEs, two of which 204, 206 support a modified paging mode. The other two UEs 210, 212 are R15 UEs.

The gNB 202 sends the SSB, TRS, and PO messages to one or more of the UEs 204, 206, 208, 210, 212 as outlined previously. However, when the gNB 202 wishes to send a PO to a UE 204, 206 that supports the modified paging mode, the gNB 202 can delay the PO as outlined below. In this simplified example, it is assumed that the gNB 202 wishes to send the PO to the first UE 204 that supports the modified paging mode.

Fig. 2 is a flow chart outlining operation of the system of Fig. 1. An example of the process of Fig. 2 is shown in Figs. 3 and 4, which are also referred to below. Fig. 3 is a diagram illustrating the power consumption associated with paging in a prior art communication system.

It should be noted that the paging occasion messages transmitted by a conventional prior art gNB (i.e. radio transmitter device) are denoted 'R15 PO' on Fig. 3 (and similarly in Fig. 4 later), while the paging occasion messages transmitted by a gNB in accordance with the present invention are denoted 'R17 PO'.

-23 -The diagram of Fig. 3 shows five frames (though the last of these is only shown partially): the n -1st frame; the nth frame; the n + lst frame; the n + 2nd frame; and the n + 3' frame, each of which is ten 1 ms slots long, for a total of 10 ms per frame. Thus the n -lst frame comprises slots 0 to 9; the nth frame comprises slots 10 to 19; the n + 1st frame comprises slots 20 to 29; the n + 2 frame comprises slots 30 to 39; and the n + 3" frame comprises slots 40 to 49 (though only slots 40 through 43 are shown, for ease of illustration). These slots are shown running from left to right in the diagram.

During certain slots, the transmitter sends certain types of transmission to the receiver(s) in the system. Specifically, the transmitter -i.e. a gNB -transmits an SSB 102 at slots 0 to 1 (n -l' frame); a TRS 104 at slots 15 to 16 (nth frame); another SSB 108 at slots 20 to 21 (n + 1st frame); and yet another SSB 110 at slots 40 to 41 (n + 3" frame). Typically, the TRS would be transmitted by the gNB once every 40 ms, while the SSB would be transmitted once every 20 ms, as shown in Fig. 3.

It can be seen in Fig. 3 that the conventional gNB would send a paging occasion message R15 PO 112 at slots 40 and 31 of the n + 3" frame, i.e. simultaneously with the corresponding SSB 110.

As can be seen in the bottom part of Fig. 3, the receiver -an R17 UE -has different relative levels of power consumption at different times, as it is operated in its various different modes. The power consumptions for this UE when communicating with the conventional gNB are given in the rows denotes 116 on Fig. 3. It should be understood that the numbers given for the power consumption are relative units, where a value of e.g. 20 would indicate a power consumption 20 times larger than the power consumption associated with the value 1. The number given in each cell, below a particular slot, is the relative power consumption of this exemplary UE during that slot.

The amount of power savings achieved with different modes is outlined in, for example, TR 38.840, which is incorporated herein by reference.

-24 -Here, the value 1 is associated with the R17 UE operating in a deep sleep, i.e. when there is no PO for the UE and so it can go into a deep sleep to drastically reduce power consumption (see slots 42 and 43). Light sleep has a relative power consumption of 20 units (i.e. 20 times more than deep sleep) and micro sleep has a relative power consumption of 45 units (i.e. 45 time more than deep sleep). The various relative powers are given for an exemplary UE, and it will be appreciated that these will typically vary in practice depending on the specific UE, however it will also be appreciated that there will generally be such relative differences in power consumption under different modes of operation in any UE.

As well as the power consumption 'cost' of operating in a given mode, there is also generally a power consumption cost associated with transitioning between different modes. In this example, a transition to and from the light sleep mode consumes 100 units of power, whereas a transition to and from the deep sleep mode consumes 450 units of power. Thus, depending on the length of sleep, a UE may pick the optimal type of sleep to minimise overall power consumption. For example, for long sleeps the UE may choose to go into the deep sleep mode, for medium sleeps it may use the light sleep mode, and for short sleeps the UE may use the micro sleep mode.

Initially, during radio resource management (RRM), the UE consumes 50 units of power per slot (see slots 0 and 1) as the first SSB 102 is received. The UE determines at that point that it can go into a light sleep, incurring the associated transition cost before operating in a light sleep mode from slots 2 to 14.

When the TRS 104 is received, the UE consumes 50 units of power conducting RRM for the two slots (slots 10 and 11) in which the TRS 104 is sent. The UE determines at that point that it can go back into the light sleep mode, incurring the associated transition cost before operating in a light sleep mode from slots 17 to 39.

During the conventional R15 PO 112 sent alongside the third SSB 110 (i.e. during slots 40 and 41 of the n + 3' frame), the UE consumes 120 units of power per slot when receiving (or being prepared to receive) the PDCCH and physical downlink shared channel (PDSCH) transmissions. The UE then switches to the deep sleep mode, incurring the associated power consumption costs from slot 42 onwards.

-25 -The total number of power units consumed when the UE is operating with the conventional gNB is 1812.

With reference to the process outlined in Fig. 2, the rows denoted 118 in Fig. 3 illustrate the power consumption of that same R17 UE when communicating with a gNB configured to operate in accordance with an embodiment of the present invention.

At an initial step 302, the gNB 202 determines a first paging frame number for a PO. In the example of Fig. 3, the first paging frame number is -n + 3, i.e. the location where the PO would be sent as 'R15 P0112 in slots 40 and 41 under legacy operation, e.g. in accordance with LTE R15.

The first paging frame number is determined by Equations 1 and 2 as outlined previously and as reproduced below, where the first paging frame number (or subframe number (SFN) for the PF (PFR15)') can, in general, be determined by Equation 1: (SFN + P Fomet) mod T = (T div N)* (UEID mod N) Equation 1: Subframe number (SFN) for the PF (PFRis) The index (is) that indicates the index of the PO in PF is determined by Equation 2 below: is = floor (UE1D/N) mod Ns Equation 2: The index (is) that indicates the index of the PO in PF The gNB 202 checks whether the UE for which it is to send the PO supports the modified paging mode at step 304. When the UE of interest (i.e. the selected radio receiver device) supports the modified paging mode, the gNB 202 determines a second paging frame number n+m at step 306.

In this embodiment, timing of the paging occasion is to be advanced (where an example in which it is delayed is given below with reference to Fig. 4). Here, n is -26 -the frame number of the first frame before the first paging frame number (i.e. before the location of R15 PO 112) that will include a IRS 104 as determined by the periodicity and the offset. In this example, the nth frame will contain the IRS 104, specifically at slots 15 and 16 as shown in Fig. 3.

Conversely, m is determined by an operational condition. In this example, m is set to 1 because the UE 204 has reported that it has low battery life (e.g. less than a threshold number of hours of battery life remaining) which is used as the operational condition in this example. If the UE 204 had more battery life remaining, m could have been set to e.g. 2 or 3, resulting in the PO being sent on the n + 2' or n + 3rd frame respectively. Additionally or alternatively, the RSRP or coverage enhancement level could be used when allocating an m value for the UE 204. However, m might also be set as some predetermined level (e.g. in line with a priority level assigned to the UE 204); set in accordance with some predetermined pattern that varies m over time; or simply randomised intermittently (e.g. at every PO).

Once the second paging frame number n + m is determined at step 306, the gNB 202 transmits the paging frame comprising the paging occasion to the radio receiver device at a time determined by the second paging frame number n + m during a further step 308, the PO being sent as 'IR17 P0'114. Thus the transmission of the PO is advanced from slots 40 and 41 in frame n + 3 to slots 20 and 21 in frame n + 1.

Alternatively, if the UE for which the PO is being sent does not support the modified paging mode, the gNB 202 transmits the paging frame comprising the PO to that UE at a time determined by the first paging frame number (i.e. during slots 40 and 41 of frame -n + 3) when the UE does not support the modified paging mode (e.g. UEs 208, 210, 212) at step 310.

In terms of power consumption, by comparing the power consumption data rows 118 accounting for the invention to the rows 116 without the invention it can be seen that operation is the same from slots 0 through 16 as described previously. However, with the invention the UE switches to a micro sleep mode (rather than the -27 -light sleep mode as per the conventional case) after receiving the TRS 104, consuming 45 units of power from slots 17 to 19.

This micro sleep is taken in anticipation of the advanced timing of the R17 PO 114 at slots 20 and 21, during which time the UE consumes 120 units of power. After this, however, the UE can go into the deep sleep mode thereafter, incurring the 450 units of power transition cost before then consuming only 1 unit of power per slot from slots 22 onwards.

The total number of power units consumed when the UE is operating with the gNB of the present invention is 1407. Compared with the conventional case of 1812 units of power, this provides a substantial power saving for the UE (i.e. a saving of over 22%).

Fig. 4 shows a further embodiment of the present invention in which modifying the PO timing instead involves delaying (rather than advancing) the timing. Fig. 4 shows five frames, from the n -4th frame to the n + ls frame. It will be appreciated that while a detailed analysis of the power consumption is not given in this case for ease of discussion, similar considerations regarding transitions to and from sleep modes and for the power consumed when receiving the same kinds of transmissions as outlined above with respect to Fig. 3 also apply to the case of Fig. 4.

In Fig. 4, the conventional gNB would sent the R15 P0400 in slots 30 and 31 of the n -1st frame, alongside an SSB. However, a gNB operating in accordance with the present invention determines that a TRS 401 is due to be sent in the nth frame. As such, the gNB delays transmission of its paging occasion message R17 PO 402.

In this particular case, the gNB has determined, based on the coverage enhancement level for the specific UE being paged, that m should be set to 1 As a result, R17 P0402 is transmitted at slots 50 and 51 in the n + 1st frame.

It will be appreciated that a radio transmitter device (e.g. a gNB) operating in accordance with embodiments of the present invention may advance and/or delay timing of the paging occasion messages for one or more UEs as appropriate.

-28 -Thus it will be appreciated by those skilled in the art that the approach of the present invention may provide a trade-off. By modifying (i.e. advancing or delaying) transmission of the PO, the paging groups (where multiple UEs are paged together) can become large, though sub-grouping can alleviate this issue. Modifying transmission of the PO may also make determination of the paging frame slightly more complex. However, in exchange for the increase in grouping size and/or complexity, embodiments of the present invention may have a significantly reduced TRS overhead for the gNB, and/or may provide for better power savings for the UEs that need it the most (e.g. UEs operating at the cell edge with low battery).

While specific embodiments of the present invention have been described in detail, it will be appreciated by those skilled in the art that the embodiments described in detail are not limiting on the scope of the claimed invention.

Claims

-29 -Claims 1. A radio transmitter device configured to communicate with a plurality of radio receiver devices, wherein one or more of said radio receiver devices is configured to support a modified paging mode, wherein said radio transmitter device is configured to: transmit a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; transmit a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; determine a first paging frame number for a paging occasion; and determine a second paging frame number n+m when the selected radio receiver device is configured to support the modified paging mode, wherein: n is a frame number of the first frame after or before the first paging frame number that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; and wherein said radio transmitter device is further configured to: transmit the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the second paging frame number when the selected radio receiver device is configured to support the modified paging mode; and transmit the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the first paging frame number when the selected radio receiver device is not configured to support the modified paging mode.
2. The radio transmitter device as claimed in claim 1, wherein the tracking reference signals comprise idle mode tracking reference signals.
3. The radio transmitter device as claimed in claim 1 or 2, wherein the operational condition comprises a parameter reported by the selected radio receiver device.
-30 - 4. The radio transmitter device as claimed in claim 3, wherein the operational condition comprises a reported battery life of the selected radio receiver device.
5. The radio transmitter device as claimed in any preceding claim, configured to transmit a reference signal to the selected radio receiver device, and to receive a reported signal strength of said reference signal from said radio receiver device, wherein the operational condition comprises the reported signal strength.
6. The radio transmitter device as claimed in any preceding claim, wherein the operational condition comprises a coverage enhancement level.
7. The radio transmitter device as claimed in any preceding claim, wherein the operational condition comprises a priority level.
8. The radio transmitter device as claimed in any preceding claim, wherein the operational condition comprises a value that varies in accordance with a predetermined pattern.
9. The radio transmitter device as claimed in any preceding claim, wherein the operational condition comprises a value that varies randomly or pseudorandomly.
10. The radio transmitter device as claimed in any preceding claim, configured to operate in accordance with a cellular wireless communication protocol, optionally wherein the cellular wireless communication protocol is a 5G communication protocol.
11. The radio transmitter device as claimed in any preceding claim, comprising a gNB.
12. The radio transmitter device as claimed in any preceding claim, configured to: transmit the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the second paging frame number only when the selected radio receiver device is further configured to support sub-grouping; and -31 -transmit the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the first paging frame number when the selected radio receiver device is not configured to support sub-grouping.
13. A radio communication system comprising the radio transmitter device as claimed in any of claims 1 to 12 and the plurality of radio devices.
14. The radio communication system as claimed in claim 13, wherein the plurality of radio receiver devices are configured to monitor said tracking reference signals when operating in an idle mode.
15. The radio communication system as claimed in claim 13 or 14, wherein one or more of the radio receiver devices is configured to transmit a reported battery life, a reported signal strength of a received reference signal, a reported coverage enhancement level, and/or a priority level to the radio transmitter device.
16. The radio communication system as claimed in any of claims 11 to 15, configured to operate in accordance with a cellular wireless communication protocol, optionally wherein the cellular wireless communication protocol is a 5G communication protocol.
17. The radio communication system as claimed in any of claims 11 to 16, wherein one of more of the radio receiver devices comprise NR UEs.
18. A method of operating a radio transmitter device configured to transmit radio signals to a plurality of radio receiver devices, wherein one or more of said radio receiver devices is configured to support a modified paging mode, the method comprising: transmitting a paging frame comprising a paging occasion for a selected radio receiver device of said plurality of radio receiver devices; transmitting a plurality of tracking reference signals to the plurality of radio receiver devices, said tracking reference signals having a periodicity and an offset; determining a first paging frame number for a paging occasion; determining a second paging frame number n+m when the selected radio receiver device is configured to support the modified paging mode, wherein: -32 -n is a frame number of the first frame after or before the first paging frame number that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition; the method further comprising: transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the second paging frame number when the selected radio receiver device is configured to support the modified paging mode; and transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the first paging frame number when the selected radio receiver device is not configured to support the modified paging mode.
19. The method as claimed in claim 18, wherein the tracking reference signals comprise idle mode tracking reference signals.
20. The method as claimed in claim 18 or 19, wherein the operational condition comprises a parameter reported by the selected radio receiver device.
21. The method as claimed in claim 20, wherein the operational condition comprises a reported battery life of the selected radio receiver device.
22. The method as claimed in any of claims 18 to 21, further comprising transmitting a reference signal to the selected radio receiver device, and receiving a reported signal strength of said reference signal from said radio receiver device, wherein the operational condition comprises the reported signal strength.
23. The method as claimed in any of claims 18 to 22, wherein the operational condition comprises a coverage enhancement level.
24. The method as claimed in any of claims 18 to 23, wherein the operational condition comprises a priority level.
-33 - 25. The method as claimed in any of claims 18 to 24, wherein the operational condition comprises a value that varies in accordance with a predetermined pattern.
26. The method as claimed in any of claims 18 to 25, wherein the operational condition comprises a value that varies randomly or pseudorandomly.
27. The method as claimed in any of claims 18 to 26, comprising operating in accordance with a cellular wireless communication protocol, optionally wherein the cellular wireless communication protocol is a 5G communication protocol.
28. The method as claimed in any of claims 18 to 27, wherein the radio transmitter device comprises a gNB.
29. The method as claimed in any of claims 18 to 28, further comprising: transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the second paging frame number only when the selected radio receiver device is further configured to support sub-grouping; and transmitting the paging frame comprising the paging occasion to the selected radio receiver device at a time determined by the first paging frame number when the selected radio receiver device is not configured to support sub-grouping.
30. A non-transitory computer-readable medium comprising instructions that, when executed by a processor, cause the processor to carry out the method as claimed in any of claims 18 to 29.
31. A radio receiver device configured to received radio signals from a radio transmitter device, said radio receiver device being configured to: support a modified paging mode; receive a tracking reference signal from the radio transmitter device, said tracking reference signal having a periodicity and an offset; and receive a paging frame comprising a paging occasion from the radio transmitter device at a time determined by a modified paging frame number n+m, wherein: -34 -n is a frame number of a frame that will include a tracking reference signal as determined by the periodicity and the offset; and m is determined by an operational condition.