Low power wake-up signal subgrouping for WUS and pei

Abstract

The present disclosure relates to methods of transmitting and receiving data on a downlink channel. A UE is assigned to a WUS subgroup and a PEI subgroup. UEID-based subgrouping is employed for the PEI subgroups and WUS subgroups. The UE monitors a WUS occasion at a first time offset relative to a paging / PDCCH monitoring occasion and, if a WUS is detected and is addressing the WUS subgroup to which the UE belongs, the UE monitors the PEI occasion at a second time offset relative to the paging / PDCCH monitoring occasion. If a PEI is detected and is addressing the PEI subgroup to which the UE belongs, the UE will continue to monitor the PDCCH in the next paging / PDCCH occasion. Techniques are disclosed to ensure that UEs in the same WUS subgroup are distributed across PEI subgroups.

Description

[0001]LOW POWER WAKE-UP SIGNAL SUBGROUPING FOR WUS AND PEI TECHNICAL FIELD The present disclosure relates generally to a wake-up receiver (WUR) for low power devices in a wireless communication network and, more particularly, to subgroup assignments for combined wake-up signal (WUS) and paging early indication (PEI) to mitigate false paging alerts. BACKGROUND In the Third Generation Partnership Project (3GPP) Release 15 (Rel-15), use of a wake-up signal (WUS) was specified for Narrowband Internet of Things (NB-IoT) and Long-Term Evolution Machine (LTE-M) to reduce energy consumption by a user equipment (UE) and to offset higher energy consumption due to coverage enhancement for the Physical Downlink Control Channel (PDCCH), which could be repeated many times. The main idea is to transmit a short WUS at a predetermined time before a paging occasion (PO). The UE wakes from a low power state to receive the WUS and, if the WUS is detected, the UE receiver remains awake to receive the PDCCH. If the WUS is not detected, the UE receiver returns to the low power mode. Power is saved because the WUS is relatively short compared to the PO and hence requires less reception time for the UE. To further reduce power consumption, a low power receiver known as a wake-up receiver, or wake-up radio (WUR) can be used. The WUR uses less power than the main receiver and monitors for a wake-up signal (WUS). The WUR wakes a main receiver in the UE when a downlink transmission for the UE is expected. The use of a WUR allows the main receiver to remain in a sleep state to save power and can significantly reduce power consumption attributable to WUS monitoring, which is particularly important for many use cases in Fifth Generation (5G) networks. Recently, the concept of a unified WUS has been proposed that can be received by either an OOK-based WUR or OFDM-based WUR. The unified WUS solution means one type of unified WUS is specified and always transmitted by the network, which can be received both by UEs with an OOK-based WUR and UEs with an OFDM-based WUR. In this way, the network could support only one type of WUS, but leave it up to UE vendors to determine whether to implement an OOK-based WUR or an OFDM-based WUR. In Release 16 (Rel-16), the use of a group wake-up signal (GWUS) was introduced to reduce the number of false paging alerts. In early implementations, the WUS would cause all UEs monitoring the same paging occasion (PO) to wake up and monitor the paging channel. This approach would cause some UEs to wake unnecessarily when the paging message is intended for another UE assigned the same PO. To reduce false paging alerts for UEs not targeted by the paging message, the UEs monitoring the same PO can be assigned to groups so that fewer UEs are woken by the WUS. In Rel-17, a wake-up signal called a paging early indication (PEI) was introduced for New (NR). The PEI is transmitted on the PDCCH and supports subgrouping of UEs to reduce false paging alerts. Recently, a proposal has been made to combine the LP-WUS / WUR with the Rel-17 PEI. Under this proposal, a UE would monitor for a WUS at a predetermined time offset before its PO and, if a WUS is detected for the UE’s WUS subgroup, the UE would continue to monitor for a PEI. If a PEI is detected for the UE’s PEI subgroup, the UE would continue to monitor the PDCCH in the legacy PO. In many implementations, subgrouping for the WUS and PEI is based on the UE identifier (UEID). For UEID-based UE subgrouping, all UEs in a WUS occasion sharing the same WUS UE subgroup may end up in the same PEI subgroup. In this case, all UEs woken up by WUS will continue to monitor the PEI. Where the WUS and PEI subgroups are the same, or have large overlap, there is little benefit in implementing PEI subgrouping. SUMMARY The present disclosure relates to methods of transmitting and receiving data on a downlink channel. The UE is assigned to a WUS subgroup and a PEI subgroup. Subgrouping is employed for the PEI subgroups and WUS subgroups. The UE monitors a WUS occasion at a first time offset relative to a paging / PDCCH monitoring occasion and, if a WUS is detected and is addressing the WUS subgroup to which the UE belongs, the UE monitors the PEI occasion at a second time offset relative to the paging / PDCCH monitoring occasion. If a PEI is detected and is addressing the PEI subgroup to which the UE belongs, the UE will continue to monitor the PDCCH in the next paging / PDCCH occasion. To ensure that UEs in the same WUS subgroup are distributed across PEI subgroups, different functions of the UEID are used to compute the PEI and WUS respectively. The functions for calculating the PEI subgroups and WUS subgroups respectively may use the same variation of the UEID or may use different variations of the UEID. A first aspect of the disclosure comprises methods of transmitting a downlink message to UE on a downlink channel. The method comprises transmitting, during a first monitoring occasion before a transmission occasion on a downlink channel, a wake-up signal (WUS) addressed to a first group of UEs, wherein the first group of UEs is determined according to a first function of a UE identifier (UEID) for a targeted UE. The method further comprises transmitting, during a second monitoring occasion before the transmission occasion on the downlink channel, a paging early indication (PEI) to a second group of UEs. The second group of UEs is determined according to a second function of the UE identifier for the targeted UE different than the first function; and transmit the downlink message in the transmission occasion to the targeted UE. In one embodiment, the first function includes a first term calculated based on a first parameter subgroupsNumForUEID indicating a number of UEID- based PEI subgroups and a second term calculated based on a second parameter indicating a number or WUS subgroups. A second aspect of the disclosure comprises a network node configured to transmit a downlink message to UE on a downlink channel. The network node is configured to transmit, during a first monitoring occasion before a transmission occasion on a downlink channel, a wake-up signal (WUS) addressed to a first group of UEs. The first group of UEs is determined according to a first function of a UE identifier (UEID) for a targeted UE. The network node is further configured to transmit, during a second monitoring occasion before the transmission occasion on the downlink channel, a paging early indication (PEI) to a second group of UEs. The second group of UEs is determined according to a second function of the UE identifier for the targeted UE different than the first function. The network node is further configured to transmit the downlink message in the transmission occasion to the targeted UE. In one embodiment, the first function includes a first term calculated based on a first parameter subgroupsNumForUEID indicating a number of UEID- based PEI subgroups and a second term calculated based on a second parameter indicating a number or WUS subgroups. A third aspect of the disclosure comprises a network node configured to transmit a downlink message to UE on a downlink channel. The network node comprises communication circuitry for communicating with the UE over a wireless communication channel and processing circuitry operatively connected to the communication circuitry. The processing circuitry is configured to transmit, during a first monitoring occasion before a transmission occasion on a downlink channel, a wake-up signal (WUS) addressed to a first group of UEs. The first group of UEs is determined according to a first function of a UE identifier (UEIDs) for a targeted UE. The processing circuitry is further configured to transmit, during a second monitoring occasion before the transmission occasion on the downlink channel, a paging early indication (PEI) to a second group of UEs. The second group of UEs is determined according to a second function of the UE identifier for the targeted UE different than the first function. The processing circuitry is further configured to transmit the downlink message in the transmission occasion to the targeted UE. In one embodiment, the first function includes a first term calculated based on a first parameter subgroupsNumForUEID indicating a number of UEID-based PEI subgroups and a second term calculated based on a second parameter indicating a number or WUS subgroups. A fourth aspect of the disclosure comprises a computer program for a UE in a wireless communication system. The computer program comprises executable instructions that, when executed by processing circuitry in the network node, causes the network node to perform the method according to the first aspect. A fifth aspect of the disclosure comprises a carrier containing a computer program according to the fourth aspect. The carrier is one of an electronic signal, optical signal, radio signal, or a non-transitory computer readable storage medium. A sixth aspect of the disclosure comprises methods implemented by a UE of receiving a downlink message from a network node on a downlink channel. The method comprises receiving, in a first monitoring occasion before a transmission occasion on a downlink channel, a wake-up signal addressed to a first group of UEs to which the UE belongs. The first group of UEs is determined according to a first function of the UE identifier (UEID) for UE. The method further comprises receiving, in a second monitoring occasion before the transmission occasion on the downlink channel, a paging early indication (PEI) addressed to a second group of UEs to which the UE belongs. The second group of UEs is determined according to a second function of the UEID for the UE different than the first function. The method further comprises receiving the downlink message the downlink channel during the transmission occasion for the downlink message. In one embodiment, the first function includes a first term calculated based on a first parameter subgroupsNumForUEID indicating a number of UEID-based PEI subgroups and a second term calculated based on a second parameter indicating a number or WUS subgroups. A seventh aspect of the disclosure comprises a UE configured to receive a downlink message from a network node on a downlink channel. The UE is configured to receive, in a first monitoring occasion before a transmission occasion on a downlink channel, a wake-up signal addressed to a first group of UEs to which the UE belongs. The first group of UEs is determined according to a first function of the UE identifier (UEID) for UE. The UE is further configured to receive, in a second monitoring occasion before the transmission occasion on the downlink channel, a paging early indication (PEI) addressed to a second group of UEs to which the UE belongs. The second group of UEs is determined according to a second function of the UEID for the UE different than the first function. The UE is further configured to receive the downlink message on the downlink channel during the transmission occasion for the downlink message. In one embodiment, the first function includes a first term calculated based on a first parameter subgroupsNumForUEID indicating a number of UEID-based PEI subgroups and a second term calculated based on a second parameter indicating a number or WUS subgroups. An eighth aspect of the disclosure comprises a UE configured to receive a downlink message from a network node on a downlink channel. The UE comprises communication circuitry for communicating with a network node over a wireless communication channel and processing circuitry operatively connected to the communication circuitry. The processing circuitry is configured to receive, in a first monitoring occasion before a transmission occasion on a downlink channel, a wake- up signal addressed to a first group of UEs to which the UE belongs. The first group of UEs is determined according to a first function of the UE identifier (UEID) for UE. The processing circuitry is further configured to receive, in a second monitoring occasion before the transmission occasion on the downlink channel, a paging early indication (PEI) addressed to a second group of UEs to which the UE belongs. The second group of UEs is determined according to a second function of the UEID for the UE different than the first function. The processing circuitry is further configured to receive the downlink message on the downlink channel during the transmission occasion for the downlink message. In one embodiment, the first function includes a first term calculated based on a first parameter subgroupsNumForUEID indicating a number of UEID-based PEI subgroups and a second term calculated based on a second parameter indicating a number or WUS subgroups. A ninth aspect of the disclosure comprises a computer program for a UE. The computer program comprises executable instructions that, when executed by processing circuitry in the UE, causes the UE to perform the method according to the sixth aspect. A tenth aspect of the disclosure comprises a carrier containing a computer program according to the ninth aspect. The carrier is one of an electronic signal, optical signal, radio signal, or a non-transitory computer readable storage medium. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 illustrates WUS and paging occasion. Figure 2 illustrates the time offset and gap for a WUS. Figure 3 illustrates time offsets for a WUS when operating in eDRX and DRX modes. Figure 4 illustrates a unified WUS for UEs using a WUR. Figure 5 illustrates coverage for a OOK-based and OFDM-based WUS. Figure 6 illustrates time durations for a OOK-based and OFDM-based WUS. Figure 7 illustrates combined WUS and PEI signaling. Figure 8 illustrates an example subgroup calculation where both UEID-based subgroups and network-assigned subgroups are used. Figure 9 illustrates an exemplary UE distribution using combined WUS and PEI signaling. Figure 10 illustrates a method implemented by a network node of transmitting a downlink message to a UE on a downlink channel. Figure 11 illustrates a method implemented by a UE of receiving a downlink message from a network node on a downlink channel. Figure 12 illustrates a network node configured to implement combined WUS and PEI signaling. Figure 13 illustrates a UE configured to implement combined WUS and PEI signaling. DETAILED DESCRIPTION Paging in Fifth Generation (5G) network is a mechanism used to notify a UE about incoming data, call requests, or network updates. When a UE is not actively involved in data transfer, it goes into an idle mode to conserve power. In idle mode, the UE monitors an assigned paging occasion (PO) for incoming paging messages. The network sends a paging message to the UE when it receives incoming data or a call request for the UE while the UE is in idle mode. Upon receiving the paging message, the UE initiates a connection establishment procedure to establish a connection with the network. In scenarios where the UE is paged infrequently, waking to monitor a PO consumes power unnecessarily when there is no paging message for the UE. A wake-up signal (WUS) can be used to reduce the amount of power consumed by the UE for monitoring POs. A WUS is a short signal transmitted on downlink control channel at a predetermined time offset before a PO that indicates to the UE that it should continue to decode the downlink (DL) control channel. The network transmits the WUS when it has data to send to the UE. The UE wakes to monitor a WUS monitoring occasion at a predetermined time offset before its assigned PO. If a WUS is not detected, the UE can go back to sleep without decoding the DL control channel. In the example shown in Figure 1, the second paging occasion (shaded black) includes a paging message for the UE. The UE will detect a WUS in the WUS monitoring occasion (shaded black) before the PO in which the paging message will be transmitted. In this case, the UE will continue to monitor the DL control channel to receive the paging message. The WUS essentially needs to contain one bit of information whereas the paging message may contain up to 35 bits of information. The short decoding time for the WUS, in turn, reduces UE power consumption and leads to longer UE battery life. A WUS can also be used in connected mode to reduce power consumption when discontinuous reception (DRX) or extended DRX (eDRX) is used. In DRX or eDRX mode, the UE may enter a low power state to conserve energy and wake periodically to monitor the PDCCH for downlink control information (DCI). When WUS is used, the network transmits a WUS in a WUS monitoring occasion a predetermined time before a PDCCH monitoring occasion. The UE wakes to receive the WUS in the WUS monitoring occasion. If no WUS is detected, indicating that no DCI for the UE is being transmitted on the PDCCH, the UE can return to the low power mode. Power is saved because the WUS is relatively short compared to the full PDCCH and hence requires less reception time for the UE. If desired, the power saved can be used to reduce latency by shortening the DRX and eDRX cycles. WUS was introduced for both LTE-M and NB-IoT with support for both DRX and extended DRX (eDRX), the former with a 1-to-1 mapping between the WUS and the PO and latter with the possible configuration of 1-to-N (many) POs. The network can configure one WUS gap for UEs using DRX, and another one for UEs using eDRX. The main motivation was further reduction in energy consumption for the UE to offset higher energy consumption due to coverage enhancement for the PDCCH, which could be repeated many times. Figure 2 illustrates a WUS for NB-IoT and LTE-M. Due to coverage enhancements, the WUS can be of variable length depending on the UE’s coverage. The UE can report its WUS capability to the network. The UE capabilities can indicate the minimum WUS gaps required for the UE to be able to decode PDCCH in the associated PO, for DRX and eDRX, respectively See, 3GPP TS 36.331. Figure 3 illustrates variable time offsets for the WUS for DRX and eDRX modes. The network can configure up to three time offsets for the WUS per PO: timeOffset-DRX, timeOffset-eDRX-Short, and timeOffset-eDRX-Long In practice, the UE will only use WUR, or timeOffset-eDRX-Long, if it is capable of starting up the main receiver as quickly as indicated by the value used in system information (SI). If not, it will fall back to using timeOffset-eDRX-Short without a WUR. Because UEs share a PO, the network may, in the worst case, have to transmit up to 3 WUSs for one PO corresponding to timeoffsetDRX, timeoffset-eDRX-Short, and timeoffset- eDRX-Long. In early implementations, the WUS would cause all UEs monitoring the same paging occasion (PO) to wake up and monitor the paging channel. This approach would cause some UEs to wake unnecessarily when the paging message is intended for another UE assigned the same PO. In the 3GPP Release 16 (Rel-16), it was agreed that WUS should be further developed to also include UE grouping, such that the number of UEs triggered by a WUS is further narrowed down to a smaller subset of the UEs that are associated with a specific PO. The purpose of these improvements is to reduce the false paging rate, i.e., reduce the number of UEs that are woken unnecessarily by a WUS transmission intended for another UE. This feature is referred to as Rel-16 group WUS, or group wake-up signaling (GWUS). In 3GPP Release 17 (Rel-17) a WUS for New Radio (NR), called ‘Paging Early Indication’ (PEI) was introduced. Because no coverage enhancement was specified for NR at that time, the only gain for Rel-17 PEI was in scenarios where the small fraction of UEs are in bad coverage and with large synchronization error due to the use of longer DRX cycles. The gain for such UEs were that, with the use of PEI, the UEs would only need to acquire one synchronization signal block (SSB) before decoding the PEI, instead of up to 3 SSBs if PEI is not used. For most UEs, Rel-17 PEI will result in gains or increased performance. Rel-17 PEI will also support UE grouping for false paging reduction, similar to the Rel-16 GWUS, which will have some gains at higher paging load. In 3GPP Release 18 (Rel-18), there has been interest in introducing a low power (LP) wake-up receiver (WUR) for NR. A WUR, also known as a wake-up radio, is a low-power receiver in a UE that monitors for the WUS and wakes a main receiver in the UE when a downlink transmission for the UE is expected. The use of a WUR allows the main receiver to remain in a sleep state to save power and can significantly reduce power consumption attributable to WUS monitoring, which is particularly important for many use cases in 5G networks. To enable use of a WUR, the time gap between the WUS and the PDCCH in the PO needs to be long enough to allow the UE to start up the main receiver. This time gap will typically be longer than the time gap for a UE that does not use a WUR. Toward the end of Rel-15, a longer WUS gap of 1s or 2s was introduced to enable the use of WUR. Conventionally, the WUS is transmitted on the PDCCH using a Orthogonal Frequency Division Multiplexing (OFDM) waveform. To enable a simpler and lower power receiver, the WUR can be implemented with simpler modulation (e.g., on-off keying (OOK)) and non-coherent detection. In this case, the WUS is not transmitted on the PDCCH. Both OFDM-based WUS and OOK-based WUS have their advantages for implementing a low-power WUR (LP-WUR). The main advantage of an OOK-based WUR is that the design is less complex and requires less power. But the OOK-based WUR requires a separate LP synchronization signal (LP-SS). The LP-SS enables the WUR to perform radio resource management (RRM) measurements with lower power, and at least coarse time and frequency synchronization. The OFDM waveform, on the other hand, can provide better coverage for a low-power (LP-WUS) with lower resource overhead. A LP-WUR receiving a OFDM waveform can reuse the primary synchronization signal (PSS) and secondary synchronization signal (SSS) to perform radio resource management (RRM) measurement and synchronization thereby avoiding the need for a separate low power (LP) synchronization signal. Timing error robustness can be further improved using a sliding window at the receiver. The benefit of WUR is reduction in the energy consumption of the main receiver, such that unless there is paging and data for the UE, it can remain in a power-saving state. This approach will extend the battery life of the device, or alternatively, enable shorter downlink latency (shorter DRX) at a fixed battery life. For short-range communication, the WUR power can be low enough (~3 µW) so that, in combination with energy harvesting, the WUR is able to remain on continuously (i.e., DRX or duty-cycling is not used) without the need for a battery. This can be considered as a key enabler of battery-less devices in Sixth Generation (6G) systems. Recently, the concept of a unified WUS has been proposed that can be received by either an OOK-based WUR or OFDM-based WUR. The network can transmit a harmonized LP-WUS signal as shown in Figure 6, where the On-periods for the OOK modulation means OFDM subcarriers are being transmitted and the Off- periods means nothing is being transmitted. With a unified WUS, one type of WUS is transmitted by the network, which can be received both by UEs with an OOK-based WUR and UEs with an OFDM-based WUR. In this way, the network can support only one type of WUS, but leave it up to UE vendors to determine whether to implement an OOK-based WUR or an OFDM-based WUR. In practice, an OOK-based WUR can have somewhat lower energy consumption, but the OFDM-based WUR will have better link performance and coverage. Figure 5 illustrates differences in coverage for OOK-based WUS and OFDM-based WUS. The OFDM-based WUS is also more efficient than the OOK- based WUS, allowing, for example, a) a larger WUS payload, b) more redundancy bits for improved decoding performance, c) multiple WUS monitoring occasions during one WUS monitoring occasion for OOK-based WUS, etc. 3GPP has recently published a study entitled “Study on low-power Wake-up Signal and Receiver for NR”. Technical Report (TR) TR 38.869, V1.0.0. According to the outcome of this study, one important consideration for WUR / WUS design is synchronization. At least for a LP-WUR that cannot receive existing PSS / SSS, a periodic LP-SS signal is beneficial for the following functionalities: (a) RRM measurements by LP-WUR, if supported; (b) at least coarse time synchronization of LP-WUR; and (c) at least coarse frequency synchronization of LP-WUR. Additional periodic LP-SS system overhead depends on LP-SS periodicity, system bandwidth (BW), number of beams, and resources required to fulfill the target functionality, etc. A periodic signal, if used for coarse synchronization, may reduce the overhead of signal preceding LP-WUS. The LP-SS can be designed to be common among UE groups (cell-specific) and further reduce system overhead. For a LP-WUR that can receive existing PSS / SSS potentially assisted by PBCH Demodulation Reference Signal (DMRS) / Tracking Reference Signal (TRS) for synchronization, existing PSS / SSS potentially assisted by PBCH DMRS / TRS may be used for the same functionality. Periodic LP-SS coverage should be equal or better than that of LP-WUS. For fine time and frequency synchronization, a signal (e.g., preamble) preceding or part of LP-WUS may be used. OFDM waveform can provide coverage for LP-WUS with lower resource overhead. LP-WUR receiving OFDMA waveform can reuse PSS / SSS to perform RRM measurement and synchronization avoiding the introduction of periodic LP-SS within the carrier. Timing error robustness can be further improved using a sliding window at the receiver. In Release 19 (Rel-19), effort is being made to specify the WUS for both RRC_IDLE / INACTVE states and RRC_CONNECTED states. One objective of this effort is to specify an LP-WUS design commonly applicable to both IDLE / INACTIVE and CONNECTED modes. The WUS signal will be an OOK-based LP-WUS with overlaid OFDM sequences. The OFDM sequence can carry information. The LP- WUS design is expected to ensure that the same information is delivered in RRC_IDLE and RRC_INACTIVE states irrespective of the LP-WUR receiver type. Embodiments of the present disclosure combine the LP-WUS and PEI as shown in Figure 7. A UE is configured to monitor a WUS occasion at a first time offset relative to a paging / PDCCH monitoring occasion. The UE is assigned to a WUS subgroup and a PEI subgroup. If a WUS is detected and is addressing the WUS subgroup to which the UE belongs, the UE will monitor the PEI occasion at a second time offset relative to the paging / PDCCH monitoring occasion. The second time offset is shorter than the first time offset. If a PEI is detected and is addressing the PEI subgroup to which the UE belongs, the UE will continue to monitor the PDCCH in the next paging / PDCCH occasion. Using both WUS and PEI reduces ‘false paging’ for the UE where the UE is unnecessarily woken up by paging for another UE, which would negatively impact the UE energy consumption. The UE can be configured to monitor both the LP-WUS and PEI, only the LP- WUS, or only the PEI. Especially for the case where LP-WUS doesn't have full coverage compared to legacy signaling, the main receiver needs to wake up to perform legacy operation out of LP-WUS coverage. In this case, the network can configure PEI as a fallback mechanism to save UE power consumption for paging monitoring. The network would also configure and transmit both LP-WUS and PEI for the UE, especially when the network is not aware of UE's entry / exit of LP-WUS monitoring. From the UE perspective, LP-WUS may be used together with PEI, if both LP-WUS and PEI are configured, to achieve more power saving gain. One aspect of the present disclosure is to further reduce false paging by implementing subgrouping for both the WUS and PEI. For UEID-based subgrouping, all UEs in a WUS occasion sharing the same WUS UE subgroup may end up in the same PEI subgroup. In this case, all UEs woken by WUS will continue to monitor the PEI. Where the WUS and PEI subgroups are the same, or have large overlap, there is little benefit in implementing PEI subgrouping. In embodiments of the present disclosure, methods are provided for more uniformly distributing UEs in the same WUS subgroup across PEI subgroups. In legacy paging operations, the paging load and UEs are spread in time over a paging frame (PF) having a plurality of POs. The PO for a UE is determined based on the UEID as follows. First, the System Frame Number (SFN) of the PF is determined according to: (SFN + PF_offset) mod T = (T div N)*(UE_ID mod N) where T is the paging cycle length, N is the total number of paging frames in T, PF- offset is an offset used for PF determination, and UE_ID is c. Next, the index (i_s), of the PO is determined by: i_s = floor (UE_ID / N) mod Ns where Ns is the number of paging occasions in a paging frame. The Rel-17 PEI subgroups are then determined according to: SubgroupID = (floor(UE_ID / (N*Ns)) mod subgroupsNumForUEID) + (subgroupsNumPerPO - subgroupsNumForUEID) where SubgroupID is the PEI subgroup for the UE, subgroupsNumForUEID is the number of UEID-based PEI subgroups, and subgroupsNumPerPO is the number of all PEI subgroups including both UEID-based groups and network assigned groups. In the following, it is assumed that UEID-based WUS and PEI subgrouping is used. The PEI subgroup is calculated as described above according to a first function of the UEID while the WUS subgroup for the UE is calculated as described according to a second function of the UEID different from the first function. The functions for calculating the PEI subgroups and WUS subgroups respectively may use the same variation of the UEID or may use different variations of the UEID. The variations may, for example, comprise two non-overlapping parts of the UEID. For example, in the case where the UEID is the 5G-S-TMSI, the UEID comprises 48 bits. In this example, the 24 most significant bits (MSBs) can be used to calculate the PEI subgroup and the 24 least significant bits (LSBs) can be used to calculate the WUS subgroup, or vice versa. In other embodiments, the first and second variations could comprise overlapping parts of the UEID. In yet other embodiments, the same UEID bits can be used for both but reordered to calculate the WUS subgroup. More generally, the first and second variations of the UEID may comprise any mathematical manipulation or function of the UEID. Using different variations of the UEID bits ensures that there will be no correlation between the PEI subgroups and WUS subgroups. Various embodiments of the disclosure for calculating the WUS subgroup ID are described below. Generally, the computation of the WUS subgroup ID takes the form: Subgroup ID = A Mod B + C, where the term A is a value calculated based on the UEID, the term B is a value computed based on a number of PEI subgroups or a number of WUS subgroups, and C is an offset based on a number of network-assigned WUS or PEI subgroups. The result of A mod B is referred to as the UEID modulus. In a first example, the PEI subgroup for a UE is determined according to the following: SubgroupID = (floor(UE_IDpei / (N*Ns)) mod subgroupsNumForUEID) + (subgroupsNumPerPO - subgroupsNumForUEID), where UE_IDpeiis the UEID bits used for calculating the PEI subgroup. The WUS subgroup is calculated according to: WUSsubgroupID = (floor(UE_IDwus / (N*Ns*subgroupsNumForUEID)) mod subgroupsNumWUS, where WUSsubgroupID is the WUS subgroup for the UE, UE_IDwusis the UEID bits used to calculate the WUS subgroup, and subgroupsNumWUS is the number of WUS subgroups. In this example, only UEID-based grouping is used for WUS. Alternatively, the WUS subgroup for the UE can be calculated according to: WUSsubgroupID = floor(floor(UE_IDwus / (N*Ns) / subgroupsNumForUEID)) mod subgroupsNumWUS, In the above equations, it is preferred that UE_IDpeiand UE_IDwusare different, which includes differences in ordering of the bits. In some embodiments,UE_IDpei and UE_IDwus may comprise different parts of the same UEID. By usingdifferent parts of the UEID to determine the PEI subgroup and WUS subgroup respectively, UEs sharing a PF / PO which also belong to the same WUS subgroup will still be evenly distributed over all defined PEI UE subgroups. If PEI subgroups based on network assignment are also used, the network-assigned subgroups will not have any correlation with UEID-based subgroups and the UEs assigned to PEI subgroups by the network would not all end up in the same WUS subgroup but would be fairly evenly spread over all groups. However, it will be appreciated that UE_IDpeiand UE_IDwusmay be the same. In a second embodiment, the total number of PEI subgroups, including the network-assigned subgroups, are included in the calculation. In this case, subgroupsNumPerPO is the total number of subgroups for both network-assigned subgrouping and UEID-based subgrouping for PEI. The WUS subgroup is determined according to: WUSsubgroupID = (floor(UE_IDwus / (N*Ns*subgroupsNumPerPO)) mod subgroupsNumForUEIDWUS) or: WUSsubgroupID =floor(floor(UE_IDwus / (N*Ns) / subgroupsNumPerPO) mod subgroupsNumForUEIDWUS Where subgroupsNumForUEIDWUS is the number of UEID-based subgroups for WUS. When network-assigned subgrouping is not being used, subgroupsNumForUEIDWUS is the total number of WUS subgroups per PO. In one variation of the previous example, when network-assigned subgrouping is possible, the network can assign a UE to a WUS subgroup. This can be done for any number of WUS subgroups. If subgroupsNumPerPOWUS is the total number of configurable subgroups per PO for WUS and 0 to K groups can be assigned by the network, the remaining WUS subgroups, if any, are determined based on UEID as herein described. In the formula below, it is assumed that the network-assigned groups are the groups 0 to K-1. WUSsubgroupID = (floor(UE_IDwus / (N*Ns*subgroupsNumPerPO)) mod subgroupsNumForUEIDWUS) + subgroupsNumPerPOWUS- subgroupsNumForUEIDWUS Figure 8 illustrates an example of subgroup calculation where both UEID- based subgroups and network-assigned subgroups are used. As shown in Figure 8, the computed UEID modulus is added to the number of network-assigned subgroups to get the subgroup ID. The network-assigned subgroups are numbered 0- K-1, where K is the total number of network-assigned subgroups and the UE-ID based subgroups are obtained by adding K to the UEID modulus. In another variation when network-assigned subgrouping is used, the network assigns a (random) network-assigned WUS subgroup ID and (random) network- assigned PEI subgroup ID to the UE. In one embodiment the UE_ID used in the calculation of WUSsubgroupID is 5G-S-TMSI mod 8192, when WUS occasion follow the DRX cycle up to 2.56 s, and it is 5G-S-TMSI mod 32768 when WUS occasion follow eDRX cycle up to 10.24s. In one embodiment the value of N corresponds to number of LP-WUS occasion (LOs) in a DRX or eDRX cycle and the value of Ns corresponds to number of LP-WUS monitoring occasion (MOs) in a LP-WUS occasion. In one embodiment, when the network supports both UEID-based and network-assigned subgrouping for WUS, it broadcasts the parameter subgroupNumPerMO (total number of subgroups for both Network-assigned subgrouping (if any) and UE_ID based subgrouping (if any) in a MO) and subgroupsNumForUEIDWUS (WUS) in system information, where the subgroupsNumForUEIDWUS is less than subgroupsNumPerMO: In one embodiment, when the network supports UE_ID subgrouping for WUS, it broadcasts parameters subgroupsNumForUEIDWUS and subgroupNumPerMO in system information. In this case subgroupNumPerMO is equal to subgroupsNumForUEIDWUS. In one embodiment, when the network supports network-assigned subgroups for WUS, it does not broadcast the parameter subgroupsNumForUEIDWUS in SI. In this case, subgroupNumPerMO defines the network-assigned subgroups for WUS. In one embodiment, the UEs in the same WUS subgroup are further sub- grouped into PEI subgroups. This can be achieved by using the UE_ID (5G-S-TMSI mod 8x(8192 or 32768)) in the above calculation i.e., the WUS groups are derived first using the UE_ID (5G-S-TMSI mod 8192 or 32768), and the WUS+PEI subgroups are derived from UE_ID (5G-S-TMSI mod 8x(8192 or 32768)). In one embodiment, the subgroup ID used for WUS and PEI in the last serving cell needs to be updated when the UE moves to another cell. Different cells may use a different number of subgroups for network-assigned or UEID-based subgroups, or it may only support a single type of subgrouping. In this case, when the UE moves to another cell within the tracking area and receives a SI update with updated subgrouping information, it needs to update the subgroup ID for WUS and PEI. In some embodiments, SI includes a flag whether a UE supporting WUS and PEI can use both. Additionally, or alternatively, SI can include a flag indicating whether a UE supporting WUS and PEI shall monitor both WUS monitoring occasions and PEI monitoring occasions. When it is indicated that a UE supporting both WUS and PEI shall monitor both WUS and PEI, the UE has two subgroup IDs: a WUS related subgroup ID (determined based on the UEID bits in WUS as normal) and one WUS+PEI related subgroup ID (determined based on the UEID bits in WUS extended with some of the reserved bits in the PEI DCI format). This approach reduces the false alarm probability by half with each additional reserved bit in PEI. There is no impact on the operation for UEs supporting WUS only or PEI only. In case the existing UEID bits in PEI are used for false alarm reduction for a UE monitoring WUS and the WUS UE does not monitor PEI, then PEI UEs experience increased false alarm rate as shown in Figure 9. In another embodiment, the WUS subgroups can be determined by using the remaining / different bits or bits in reverse order of 5G-S-TMSI when determining the UEID to ensure that the is no correlation between the PEI and WUS subgroups based on the UEID. This should also be determined regardless of whether eDRX is applied. Currently, UEID is determined as follows: 5G-S-TMSI mod X, where X is 32768, if eDRX is applied; otherwise, X is 8192 (TS 38.304) In this embodiment even higher priority UEID bits, e.g., 5G-S-TMSI mod X, where X is 262144 if one considers maximum 8 WUS subgroups in total, are used to determine the WUS subgroup whereas the currently specified part of the 5G-S-TMSI bits determine the PEI subgroup (and PF). The proposed mechanism is beneficial since it would make it optional for a UE (i.e., up to UE implementation as agreed in RAN1#116) to support either WUS, PEI or both with no dependency for supporting these power saving features. For the proposed scheme the WUS subgroup IDs can be determined as follows: WUSsubgroupID = (floor(UE_ID / (N*Ns)) mod subgroupsNumForUEIDWUS) where UE_ID: 5G-S-TMSI mod X, where X is 262144, if eDRX is applied; otherwise, X is 65536 and subgroupsNumForUEIDWUS is number of WUS subgroups for UE_ID based subgrouping in a PO, which is broadcasted in system information. In another embodiment, network-assigned grouping is introduced for WUS and the formula above is updated as follows: WUSsubgroupID = (floor(UE_IDwus / (N*Ns)) mod subgroupsNumForUEIDWUS) + (subgroupsNumPerPO - subgroupsNumForUEIDWUS) where subgroupsNumPerPOWUS is the total number of WUS subgroups for both Network-assigned subgrouping (if any) and UE_ID based subgrouping (if any) in a PO, which is broadcasted in SI.; Figure 10 illustrates an exemplary method 100 implemented by a network node (e.g., base station) in a wireless communication network for transmitting a downlink message to a UE on a downlink channel. The network node transmits, during a first monitoring occasion before a transmission occasion on a downlink channel, a wake-up signal (WUS) addressed to a first group of UEs to which a targeted UE belongs (block 110). The first group of UEs is determined according to a first function of a UE identifier (UEID) for a targeted UE. The network node then transmits, during a second monitoring occasion before the transmission occasion on the downlink channel, a paging early indication (PEI) to a second group of UEs to which the targeted UE belongs (block 120). The second group of UEs is determined according to a second function of the UE identifier for the targeted UE different than the first function. The network node then transmits the downlink message in the transmission occasion to the targeted UE (block 130). In some embodiments of method 100, the WUS comprises a low power WUS transmitted with On-Off keying (OOK) modulation. In some embodiments of method 100, the WUS comprises a unified low power WUS transmitted with On-Off keying (OOK) modulation overlaid with Orthogonal Frequency Division Multiplexing (OFDM) modulation. In some embodiments of method 100, the PEI is transmitted with Orthogonal Frequency Division Multiplexing (OFDM) modulation. In some embodiments of method 100, the PEI is transmitted on a downlink control channel. In some embodiments of method 100, the first group is one of a plurality of Wake-up Signal (WUS) subgroups for a paging occasion and the second group is one of a plurality of PEI subgroups for the paging occasion. In some embodiments of method 100, the plurality of PEI subgroups includes UEID-based PEI subgroups and network-assigned PEI subgroups and the second group comprises a UEID-based PEI subgroup. In some embodiments of method 100, the first function includes a first term calculated based on a first parameter indicating a number of PEI subgroups and a second term calculated based on a second parameter indicating a number or WUS subgroups. In some embodiments of method 100, the first group is determined based on a modulus of the first term divided by the second term. In some embodiments of method 100, the first group is determined by adding on offset to the modulus of the first term divided by the second term, wherein the offset indicates a number of network assigned subgroups. In some embodiments of method 100, the first term is calculated according to: floor(UE_ID / (N*Ns*subgroupsNumForUEID) where subgroupsNumForUEID indicates a number of UEID-based PEI subgroups. In some embodiments of method 100, the second parameter is subgroupsNumWUS and indicates a total number of WUS subgroups. In some embodiments of method 100, the plurality of WUS subgroups includes UEID-based WUS subgroups and network-assigned WUS subgroups and the first group comprises a UEID-based WUS subgroup. Some embodiments of method 100 further comprise transmitting, in a broadcast message, the total number of WUS subgroups per paging occasion. Some embodiments of method 100 further comprise transmitting, in a broadcast message, the total number of UEID-based WUS subgroups per paging occasion. Figure 11 illustrates an exemplary method 150 implemented by a UE in a wireless communication network for receiving a downlink message from the network node on a downlink channel. The UE receives, in a first monitoring occasion before a transmission occasion on a downlink channel, a wake-up signal addressed to a first group of UEs to which the UE belongs (block 160). The first group of UEs is determined according to a first function of the UE identifier (UEID) for UE. The UE then receives, in a second monitoring occasion before the transmission occasion on the downlink channel, a paging early indication (PEI) addressed to a second group of UEs to which the UE belongs (block 170). The second group of UEs is determined according or a second function of the UEID different than the first function. The UE then receives the downlink message the downlink channel during the transmission occasion for the downlink message (block 180). In some embodiments of method 150, the WUS comprises a low power WUS transmitted with On-Off keying (OOK) modulation. In some embodiments of method 150, the WUS comprises a unified low power WUS transmitted with On-Off keying (OOK) modulation overlaid with Orthogonal Frequency Division Multiplexing (OFDM) modulation. In some embodiments of method 150, the PEI is transmitted with Orthogonal Frequency Division Multiplexing (OFDM) modulation. In some embodiments of method 150, the PEI is received on a downlink control channel. Some embodiments of method 150 further comprise receiving the WUS with a low power receiver; waking a main receiver responsive to reception of the WUS; and receiving the PEI with the min receiver. In some embodiments of method 150, the first group is one of a plurality of Wake-up Signal (WUS) subgroups for a paging occasion and the second group is one of a plurality of PEI subgroups for the paging occasion. In some embodiments of method 150, the plurality of PEI subgroups include UEID-based subgroups and network-assigned subgroups and the second group comprises a UEID-based PEI subgroup. In some embodiments of method 150, the first function includes a first term calculated based on a first parameter indicating a number of PEI subgroups and a second term calculated based on a second parameter indicating a number or WUS subgroups. In some embodiments of method 150, the first group is determined based on a modulus of the first term divided by the second term. In some embodiments of method 150, the first group is determined by adding an offset to the modulus of the first term divided by the second term, wherein the offset indicates a number of network assigned subgroups. In some embodiments of method 150, the first term is calculated according to: floor(UE_ID / (N*Ns*subgroupsNumForUEID) where subgroupsNumForUEID indicates a number of UEID-based PEI subgroups. In some embodiments of method 150, the first group is determined based on a modulus of the first term divided by the second term. In some embodiments of method 150, the second parameter is subgroupsNumWUS and indicates a total number of WUS subgroups. In some embodiments of method 150, the plurality of WUS subgroups includes UEID-based WUS subgroups and network-assigned WUS subgroups and the first group comprises a UEID-based WUS subgroup. Some embodiments of method 150, further comprise receiving, in a broadcast message, the total number of WUS subgroups per paging occasion. Some embodiments of method 150, further comprise receiving, in a broadcast message, the total number of UEID-based WUS subgroups per paging occasion. An apparatus can perform any of the methods herein described by implementing any functional means, modules, units, or circuitry. In one embodiment, for example, the apparatuses comprise respective circuits or circuitry configured to perform the steps shown in the method figures. The circuits or circuitry in this regard may comprise circuits dedicated to performing certain functional processing and / or one or more microprocessors in conjunction with memory. For instance, the circuitry may include one or more microprocessor or microcontrollers, as well as other digital hardware, which may include Digital Signal Processors (DSPs), special-purpose digital logic, and the like. The processing circuitry may be configured to execute program code stored in memory, which may include one or several types of memory such as read-only memory (ROM), random-access memory, cache memory, flash memory devices, optical storage devices, etc. Program code stored in memory may include program instructions for executing one or more telecommunications and / or data communications protocols as well as instructions for carrying out one or more of the techniques described herein, in several embodiments. In embodiments that employ memory, the memory stores program code that, when executed by one or more processors, carries out the techniques described herein Figure 12 illustrates the main functional components of a network node 200, which may comprise a base station, distributed unit, centralized unit, or other RAN node. The network node 200 comprises one or more antenna panels 210, communication circuitry 220, processing circuitry 230, and memory 240. Each antenna panel 210 comprises a plurality of antenna elements. The antenna panels 210 may comprise, for example, a phased array antenna. The antenna panels 210 may be arranged to transmit and receive in different directions. In some embodiments, the communication circuitry 220 comprises both radio frequency (RF) circuitry 222 and network interface circuitry (NIC) 224. The RF circuitry 222 can be located at one or more TRPs and comprises the RF components necessary for communicating with UEs over a wireless communication link. The RF circuitry may comprise, for example, a transmitter and receiver coupled to the antenna panels 210 and configured to operate according to the 2G standards or other wireless communication standard. The communication circuitry 220 comprises network interface circuitry for communication with other RAN nodes, core network nodes, and or external systems. The network interface circuitry may, for example, comprise an Ethernet interface, optical network interface, or a wireless interface. The processing circuitry 230 comprises one or more microprocessors, hardware, firmware, or a combination thereof that controls the overall operation of the RAN node 200. The processing circuitry 230 can be configured by software to perform one or more of the methods herein described including the method 100 shown in Figure 9. Memory 240 comprises both volatile and non-volatile memory for storing computer program code and data needed by the processing circuitry 230 for operation. Memory 240 may comprise any tangible, non-transitory computer- readable storage medium for storing data including electronic, magnetic, optical, electromagnetic, or semiconductor data storage. Memory 240 stores a computer program 250 comprising executable instructions that configure the processing circuit 230 in the network node 200 to perform one or more of the methods herein described including the method 100 shown in Figure 10. A computer program 250 in this regard may comprise one or more code modules corresponding to the means or units described above. In general, computer program instructions and configuration information are stored in a non-volatile memory, such as a ROM, erasable programmable read only memory (EPROM) or flash memory. Temporary data generated during operation may be stored in a volatile memory, such as a random access memory (RAM). In some embodiments, computer program 250 for configuring the processing circuitry 230 as herein described may be stored in a removable memory, such as a portable compact disc, portable digital video disc, or other removable media. The computer program 250 may also be embodied in a carrier such as an electronic signal, optical signal, radio signal, or computer readable storage medium. Figure 13 illustrates the main functional components of a UE 300. The UE 300 comprises one or more antenna panels 310, communication circuitry 320, processing circuitry 330, and memory 340. Each antenna panel 310 comprises a plurality of antenna elements. The antenna panels 310 may comprise, for example, a phased array antenna. The antenna panels 310 may be arranged to transmit and receive in different directions. The communication circuitry 320 connects to the antenna panel 310 and comprises a main radio 322 and a WUR 324. The main radio 322 may comprise, for example, a transmitter and receiver coupled to the antenna panels 310 and configured to operate according to the 5G standards or other wireless communication standard. The WUR comprises a low power receiver configured to receive a WUS from serving base station. The processing circuitry 330 comprises one or more microprocessors, hardware, firmware, or a combination thereof that control the overall operation of the UE0. The processing circuitry 330 can be configured by software to perform the methods herein described including the method 150 shown in Figure 11. Memory 340 comprises both volatile and non-volatile memory for storing computer program code and data needed by the processing circuitry 330 for operation. Memory 340 may comprise any tangible, non-transitory computer- readable storage medium for storing data including electronic, magnetic, optical, electromagnetic, or semiconductor data storage. Memory 340 stores a computer program 350 comprising executable instructions that configure the processing circuit 330 in the UE0 to perform the methods herein described including the method 150 shown in Figure 11. A computer program 350 in this regard may comprise one or more code modules corresponding to the means or units described above. In general, computer program instructions and configuration information are stored in a non-volatile memory, such as a ROM, erasable programmable read only memory (EPROM) or flash memory. Temporary data generated during operation may be stored in a volatile memory, such as a random access memory (RAM). In some embodiments, computer program 350 for configuring the processing circuitry 330 as herein described may be stored in a removable memory, such as a portable compact disc, portable digital video disc, or other removable media. The computer program 350 may also be embodied in a carrier such as an electronic signal, optical signal, radio signal, or computer readable storage medium. Those skilled in the art will also appreciate that embodiments herein further include corresponding computer programs. A computer program comprises instructions which, when executed on at least one processor of an apparatus, cause the apparatus to carry out any of the respective processing described above. A computer program in this regard may comprise one or more code modules corresponding to the means or units described above. Embodiments further include a carrier containing such a computer program. This carrier may comprise one of an electronic signal, optical signal, radio signal, or computer readable storage medium. In this regard, embodiments herein also include a computer program product stored on a non-transitory computer readable (storage or recording) medium and comprising instructions that, when executed by a processor of an apparatus, cause the apparatus to perform as described above. Embodiments further include a computer program product comprising program code portions for performing the steps of any of the embodiments herein when the computer program product is executed by a computing device. This computer program product may be stored on a computer readable recording medium.

Claims

CLAIMS 1. A method implemented by a network node (200) in a wireless communication network of sending a downlink message to a user equipment, UE (300), the method, comprising: transmitting, during a first monitoring occasion before a transmission occasion on a downlink channel, a wake-up signal, WUS, addressed to a first group of UEs to which a targeted UE (300) belongs, wherein the first group of UEs is determined according to a first function of a UE identifier, UEID, for the targeted UE (300); transmitting, during a second monitoring occasion before the transmission occasion on the downlink channel, a paging early indication, PEI to a second group of UEs to which the targeted UE (300) belongs, wherein the second group of UEs is determined according to a second function of the UEID for the targeted UE (300) different than the first function; and transmitting the downlink message in the transmission occasion to the targeted UE (300).

2. The method according to claim 1, wherein the WUS comprises a low power WUS transmitted with On-Off keying, OOK, modulation.

3. The method according to claim 2, wherein the WUS comprises a unified low power WUS transmitted with On-Off keying, OOK, modulation overlaid with Orthogonal Frequency Division Multiplexing, OFDM, modulation.

4. The method according to claim 1, wherein the PEI is transmitted with Orthogonal Frequency Division Multiplexing, OFDM, modulation.

5. The method according to claim 4 wherein the PEI is transmitted on a downlink control channel.

6. The method according to claim 1, wherein the first group is one of a plurality of Wake-up Signal, WUS, subgroups for a paging occasion and the second group is one of a plurality of PEI subgroups for the paging occasion.

7. The method according to claim 6, wherein the plurality of PEI subgroups includes UEID-based PEI subgroups and network-assigned PEI subgroups and the second group comprises a UEID-based PEI subgroup.

8. The method according to claim 7 wherein the first function includes a first term calculated based on a first parameter indicating a number of PEI subgroups and a second term calculated based on a second parameter indicating a number or WUS subgroups.

9. The method according to claim 8, wherein the first group is determined based on a modulus of the first term divided by the second term.

10. The method according to claim 9, wherein the first group is determined by adding on offset to the modulus of the first term divided by the second term, wherein the offset indicates a number of network assigned subgroups.

11. The method according to claim 8 wherein the first term is calculated according to: floor(UE_ID / (N*Ns*subgroupsNumForUEID) where subgroupsNumForUEID indicates a number of UEID-based PEI subgroups.

12. The method according to claim 10, wherein the second parameter is subgroupsNumWUS and indicates a total number of WUS subgroups.

13. The method according to claim 10 wherein the plurality of WUS subgroups includes UEID-based WUS subgroups and network-assigned WUS subgroups and the first group comprises a UEID-based WUS subgroup.

14. The method according to claim 13, further comprising transmitting, in a broadcast message, the total number of WUS subgroups per paging occasion.

15. The method according to –claim 13, further comprising transmitting, in a broadcast message, the total number of UEID-based WUS subgroups per paging occasion.

16. A method implemented by a user-equipment, UE (300), in a wireless communication network of receiving a downlink message from a network node (200), comprising: receiving, in a first monitoring occasion before a transmission occasion on a downlink channel, a wake-up signal addressed to a first group of UEs to which the UE belongs, wherein the first group of UEs is determined according to a first function of the UE identifier, UEID, for the UE (300); receiving, in a second monitoring occasion before the transmission occasion on the downlink channel, a paging early indication, PEI, addressed to a second group of UEs to which the UE (300) belongs, wherein the second group of UEs is determined according to a second function of the UEID for the UE (300) different than the first function; and receiving the downlink message on the downlink channel during the transmission occasion for the downlink message.

17. The method according to claim 16, wherein the WUS comprises a low power WUS transmitted with On-Off keying, OOK, modulation.

18. The method according to claim 16, wherein the WUS comprises a unified low power WUS transmitted with On-Off keying, OOK, modulation overlaid with Orthogonal Frequency Division Multiplexing, OFDM, modulation.

19. The method according to claim 16, wherein the PEI is transmitted with Orthogonal Frequency Division Multiplexing, OFDM, modulation.

20. The method according to claim 19 wherein the PEI is received on a downlink control channel.

21. The method according to claim 16, further comprising:receiving the WUS with a low power receiver; waking a main receiver responsive to reception of the WUS; and receiving the PEI with the min receiver.

22. The method according to claim 16, wherein the first group is one of a plurality of Wake-up Signal, WUS, subgroups for a paging occasion and the second group is one of a plurality of PEI subgroups for the paging occasion.

23. The method according to claim 22, wherein the plurality of PEI subgroups includes UEID-based subgroups and network-assigned subgroups and the second group comprises a UEID-based PEI subgroup.

24. The method according to claim 23 wherein the first function includes a first term calculated based on a first parameter indicating a number of PEI subgroups and a second term calculated based on a second parameter indicating a number or WUS subgroups.

25. The method according to claim 24, wherein the first group is determined based on a modulus of the first term divided by the second term.

26. The method according to claim 25, wherein the first group is determined by adding an offset to the modulus of the first term divided by the second term, wherein the offset indicates a number of network assigned subgroups.

27. The method according to claim 24 wherein the first term is calculated according to: floor(UE_ID / (N*Ns*subgroupsNumForUEID) where subgroupsNumForUEID indicates a number of UEID-based PEI subgroups.

28. The method according to claim 27, wherein the first group is determined based on a modulus of the first term divided by the second term.

29. The method according to claim 28, wherein the second parameter is subgroupsNumWUS and indicates a total number of WUS subgroups.

30. The method according to claim 28 wherein the plurality of WUS subgroups includes UEID-based WUS subgroups and network-assigned WUS subgroups and the first group comprises a UEID-based WUS subgroup.

31. The method according to claim 16, further comprising receiving, in a broadcast message, the total number of WUS subgroups per paging occasion.

32. The method according to claim 16, further comprising receiving, in a broadcast message, the total number of UEID-based WUS subgroups per paging occasion.

33. A network node (200) configured to send a wake-up signal, WUS, to a user equipment, UE (300), having a wake-up receiver, WUR, the network node (200) comprising: communication circuitry for communicating with the UE (300) over a wireless communication channel; and processing circuitry operatively connected to the communication circuitry, the processing circuitry being configured to: send, during a first monitoring occasion before a transmission occasion on a downlink channel, the WUS addressed to a first group of UEs, wherein the first group of UEs is determined according to a first function of a UE identifier, UEIDs, for a targeted UE (300); send, during a second monitoring occasion before the transmission occasion on the downlink channel, a paging early indication, PEI, to a second group of UEs, wherein the second group of UEs is determined according to a second function of the UEID for the targeted UE (300) different than the first function; and transmit the downlink message in the transmission occasion to the targeted UE (300).

34. A user equipment, UE (300), having a wake-up receiver, WUR, the UE (300) comprising: communication circuitry for communicating with a network node (200) in a wireless communication network; and processing circuitry operatively connected to the communication circuitry, the processing circuitry being configured to: receive, in a first monitoring occasion before a transmission occasion on a downlink channel, a wake-up signal addressed to a first group of UEs to which the UE (300) belongs, wherein the first group of UEs is determined according to a first function of a UE identifier, UEID, for the UE (300); receive, in a second monitoring occasion before the transmission occasion on the downlink channel, a paging early indication, PEI, addressed to a second group of UEs to which the UE (300) belongs, wherein the second group of UEs is determined according to a second function of the UEID for the UE (300) different than the first function; and receive the downlink message on the downlink channel during the transmission occasion for the downlink message.

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