Method and apparatus for robust small data transmission in wireless network

Abstract

A method and apparatus for robust small data transmission in a wireless network. The present disclosure relates to methods, apparatuses and systems for performing robust small data transmissions from a base station to a user equipment when the user equipment of a wireless communication network is in an inactive state. The disclosed method comprises the following steps performed by a user equipment (101): receiving (203) a paging notification from a base station in an inactive state (200), performing a signal quality measurement (205), in response to the received paging notification, sending a message (206) comprising at least a channel quality indication to the base station, and receiving (210) a message (209) comprising downlink data from the base station (102), the message (209) is transmitted using a modulation scheme selected (207) by the base station (102) based on the reported channel quality indication.

Description

Technical Field

[0001] The present application relates generally to wireless communications, and more particularly, to apparatus and methods for improving small data transmission (SDT) in a radio resource control (RRC) inactive state. Background Art

[0002] Because the transition from the RRC inactive or RRC idle state to the RRC connected state may cause overhead to the UE when only a small amount of data is to be transmitted, the 3rd Generation Partnership Project (3GPP) has introduced techniques for optimizing the transmission of such small packets. In practice, the UE needs to exchange multiple control signals to initiate and maintain a connection with the network. When the payload size is relatively small compared to the amount of control signals, establishing a connection becomes a concern for both the network and the UE due to the control signaling overhead.

[0003] Small Data Transfer (SDT) in RRC Inactive state has been introduced in 3GPP Release 17 for 5G NR to reduce the signaling overhead and UE power consumption for infrequent data transmission. This allows the UE to transmit sporadic small amounts of data in RRC Inactive state without the need for RRC state transition.

[0004] The RRC inactive state is introduced to maintain the AS (Access Stratum) context at the base station and the UE, with the aim of reducing energy consumption and the number of messages exchanged between the user equipment and the base station. In the RRC inactive state, the user equipment and the base station suspend their radio connection, but the AS context is retained in the user equipment and the base station.

[0005] Depending on how the radio resources are configured, 3GPP defines two types of SDT: SDT using random access (RA-SDT) and SDT using pre-configured grants (CG-SDT). RACH (Random Access Channel)-based SDT allows SDT to be performed using an uplink grant for SDT received via a random access procedure. CG-based SDT allows SDT to be performed using a configured grant in an RRC inactive state without performing a random access procedure.

[0006] Small data transmission using preconfigured radio resources is referred to as transmission via PUR (preconfigured uplink resources) in the LTE standard and as transmission via CG-SDT (configuration grant-based SDT) in the 5G NR standard. The base station configures the radio resources when the user equipment transitions from RRC connected to RRC inactive state, for example with an RRC release message including the radio resource configuration of PUR for CG-SDT.

[0007] Small data transmission using random access is called EDT (Early Data Transfer) in the LTE standard and RA-SDT (Random Access-based SDT) in the 5G NR (New Radio) standard. Data is transmitted using shared radio resources using a random access procedure.

[0008] Basically, when the base station needs to send a small amount of data to a user equipment in the RRC inactive state, the base station sends a paging notification to the user equipment. Such paging messages are sent in SSB (Signal Synchronization Block) using QPSK (Quadrature Phase Shift Keying) modulation for the Physical Downlink Control Channel (PDCCH), so that the user equipment can decode the message even under low RSRP (Reference Signal Received Power) conditions. However, the actual downlink data transmission cannot be carried by QPSK modulation under low RSRP conditions and may suffer from errors, resulting in packet retransmissions and overhead.

[0009] Therefore, a robust way to transmit small data in RRC inactive state is needed. Summary of the invention

[0010] In one aspect, a method for receiving a small data transmission (SDT) by a user equipment connected to a wireless communication network is proposed. The method comprises the following actions:

[0011] - Receive paging notifications from base stations in inactive state,

[0012] - perform signal quality measurements,

[0013] - in response to the received paging notification, sending a message including at least a channel quality indication report to the base station, and

[0014] - receiving from the base station a message comprising downlink data, the message being transmitted using a modulation scheme selected by the base station based on the reported channel quality indication.

[0015] Upon receiving a paging message from the base station indicating that downlink data is available, the user equipment can therefore perform channel quality measurements and transmit a channel quality report to the base station, such as a CQI index defined by 3GPP. Then, using the channel quality indicator, the base station can select and use the most appropriate modulation scheme to transmit data over the channel. In this way, transmission errors can be reduced and retransmissions can be avoided, thereby limiting signaling overhead and power consumption.

[0016] According to an embodiment, the signal quality indication is reported in a msg3 message and the downlink data is received in a msg4 message.

[0017] Therefore, the present disclosure contemplates that the user equipment sends a channel quality indication in the Msg3 message together with the RRC recovery request message. Then, when sending a small amount of data in Msg4, the base station serving the UE can select the MCS (modulation and coding scheme) based on the channel quality indication.

[0018] According to an embodiment, the signal quality indication is reported in a msgA message and the downlink data is received in a msgB message.

[0019] To reduce latency and signaling overhead, 3GPP introduced a two-step random access procedure. This is achieved by combining the random access preamble (Msg1) and the scheduled PUSCH transmission (Msg3) into a single message MsgA from the UE and by combining the random access response Msg2 and the contention resolution message Msg4 into a single message MsgB from the base station to the user equipment.

[0020] Therefore, the present disclosure contemplates that the user equipment sends a channel quality indication in an MsgA message together with a random access preamble. Downlink data may then be received in an MsgB message using an MCS selected based on the channel quality indication sent to the base station in an MsgB message. Such a provision is particularly relevant in EDT (Early Data Transfer) or RA-SDT (Random Access-Small Data Transfer) scenarios.

[0021] According to an embodiment, the signal quality indication is reported on a physical uplink shared channel (PUSCH) using a resource grant configured by the base station prior to entering the RRC inactive state.

[0022] Therefore, it is proposed that when resource grant is preconfigured, such as in case of PUR or CG-SDT, the user equipment sends a channel quality indication to the base station through PUSCH (Physical Uplink Shared Channel).

[0023] According to an embodiment, the method comprises the step of receiving a message comprising initial downlink data from a base station prior to reporting the channel quality indication, wherein the initial downlink data is transmitted using a preconfigured low modulation scheme.

[0024] It is proposed to always transmit the first downlink small data burst using a low modulation scheme (like QPSK) to limit the risk of transmission errors even in bad radio conditions.

[0025] According to an embodiment, the message sent in response to the received paging notification further comprises at least one neighbor beam indication.

[0026] Based on such information, the base station can replicate the downlink data transmission in more than one beam. As a result, the transmission will be more robust.

[0027] The present disclosure also relates to an apparatus for receiving a small data transmission (SDT) from a base station in a wireless communication network, the apparatus comprising a processor coupled to a memory having computer program instructions stored therein, the instructions being configured to perform the following actions when executed by the processor:

[0028] - Receive paging notifications from base stations in inactive state,

[0029] - perform signal quality measurements,

[0030] - in response to the received paging notification, sending a message including at least a channel quality indication report to the base station, and

[0031] - receiving from the base station a message comprising downlink data, the message being transmitted using a modulation scheme selected by the base station based on the reported channel quality indication.

[0032] The present disclosure also relates to a user equipment, which includes the apparatus for receiving a small data transmission (SDT) from a base station as described above.

[0033] Another aspect of the present disclosure relates to a method for sending a small data transmission by a base station of a wireless communication network, the method comprising:

[0034] - Send a paging notification to the user equipment,

[0035] - receiving a response message to the paging notification, the message comprising at least a radio signal quality indicator report measured by the user equipment,

[0036] - transmitting a message comprising downlink data to said user equipment, said message being transmitted using a modulation scheme selected in dependence on the received radio signal quality indicator.

[0037] According to an embodiment, the signal quality indicator is received in a msgA message and the downlink data is sent in a msgB message.

[0038] According to an embodiment, the signal quality indicator is received in a msg3 message and the downlink data is sent in a msg4 message.

[0039] According to an embodiment, the signal quality indicator is received on a physical uplink shared channel (PUSCH) using a resource grant configured prior to entering the RRC inactive state.

[0040] According to an embodiment, the method comprises: transmitting small data on at least two beams when the message received in response to the paging notification further comprises at least one neighbor beam indication.

[0041] The present disclosure also relates to an apparatus for transmitting a small data transmission (SDT) to a user equipment in a wireless communication network, the apparatus comprising a processor coupled to a memory having computer program instructions stored therein, the instructions being configured to perform the following actions when executed by the processor:

[0042] - Send a paging notification to the user equipment,

[0043] - receiving a response message to the paging notification, the message comprising at least a radio signal quality indicator report measured by the user equipment,

[0044] - transmitting a message comprising downlink data to said user equipment, said message being transmitted using a modulation scheme selected in dependence on the received radio signal quality indicator.

[0045] The present disclosure also relates to a base station, which includes an apparatus for transmitting a small data transmission (SDT) from the base station as described above.

[0046] A system for performing small data transmission in a wireless network including a base station and a user equipment, wherein the base station includes a processor coupled to a memory having computer program instructions stored therein, the instructions being configured to perform the following actions:

[0047] - sending a paging notification to the user equipment,

[0048] - receiving a response message to the paging notification, the message comprising at least a radio signal quality indicator report measured by the user equipment,

[0049] - transmitting a message comprising downlink data to the user equipment, the message being transmitted using a modulation scheme selected in dependence on the received radio signal quality indicator, and

[0050] The user equipment comprises a processor coupled to a memory having computer program instructions stored therein, the instructions being configured to perform the following actions:

[0051] - Receive paging notifications from base stations in inactive state,

[0052] - perform signal quality measurements,

[0053] - in response to the received paging notification, sending a message including at least a channel quality indication report to the base station, and

[0054] - receiving from the base station a message comprising downlink data, the message being transmitted using a modulation scheme selected by the base station based on the reported channel quality indication.

[0055] In some embodiments, the various steps of the method for receiving a small data transmission by a user equipment and / or the method for sending a small data transmission by a base station are determined by instructions of a computer program.

[0056] Therefore, the present disclosure further contemplates computer programs on an information medium, which are suitable for implementation in a user equipment and a base station, respectively, or more generally in a computer, which programs respectively include instructions adapted to implement the steps of the wireless communication method disclosed herein, which is supported by the user equipment and performed by the base station, respectively.

[0057] These programs may use any programming language and may be in the form of source code, object code, or an intermediate code between source code and object code, such as partially compiled form or any other desired form.

[0058] On the other hand, an information medium readable by a computer is envisaged, which information medium comprises instructions of a computer program such as mentioned above.

[0059] The information medium may be any entity or device capable of storing a program. For example, the medium may include a storage device such as a ROM (e.g., a CD ROM or a microelectronic circuit ROM), an EEPROM, a FLASH memory, or any magnetic recording device (e.g., a hard disk drive).

[0060] Furthermore, the information medium may be a transmissible medium such as an electric signal or an optical signal that can be transmitted via an electric or optical cable by radio or by other means.In particular, the program according to the embodiment of the present invention may be downloaded from a network.

[0061] Alternatively, the information medium may be an integrated circuit in which the program is embodied, the circuit being arranged to execute or to be used for executing the method in question.

[0062] The advantages of the device, user equipment, base station, system, corresponding computer program and information medium are the same as those of the device, user equipment, base station, system, corresponding computer program and information medium presented in relation to the method for receiving small data according to any one of the embodiments mentioned above. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Other advantages and characteristics of the invention will become more apparent on reading the following description, given by way of simple illustrative and non-limiting examples, and the accompanying drawings, in which:

[0064] - Figure 1 A wireless system including user equipment and a base station in which aspects of the present disclosure may be practiced is presented.

[0065] - Figure 2is a simplified diagram showing an example of small data transmission terminated by a UE in an RRC inactive state according to the first embodiment,

[0066] - Figure 3 is a simplified diagram showing an example of small data transmission terminated by a UE in an RRC inactive state according to the second embodiment,

[0067] - Figure 4 is a block diagram of an apparatus for receiving a small data transmission according to an embodiment,

[0068] - Figure 5 is a block diagram of an apparatus for sending a small data transmission according to an embodiment. DETAILED DESCRIPTION

[0069] The specific embodiments described below with reference to the accompanying drawings are intended as descriptions of various configurations and are not intended to represent the only configurations in which the concepts described herein may be practiced. The specific embodiments include specific details to provide a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In particular, although terminology from 3GPP 5G NR may be used in this disclosure to illustrate the embodiments herein, this should not be viewed as limiting the scope of the invention.

[0070] Figure 1 An exemplary 5G New Radio (NR) wireless communication system 100 including user equipment 101 and base station 102 in which aspects of the present disclosure may be practiced is shown. Wireless network 100 may be an LTE network or some other wireless network, such as an LTE, 5G, or NR network. Wireless network 100 may include one or more base stations 102. Depending on the wireless standard implemented, base station 102 may be referred to as a BS, NB, eNodeB (or eNB), gNodeB (or gNB), access point, etc. Base station 102 provides radio communication coverage for a specific geographic area called a "cell".

[0071] The user device 101 may be referred to as a mobile station, a wireless terminal, etc. In some examples, the user device 101 may be a cellular phone, a wireless modem, a wireless communication device, a handheld device, a laptop computer, etc. The user device 101 may also be an IoT (Internet of Things) device like a wireless camera, a smart sensor or smart meter, a vehicle, a global positioning system device, or any other device configured to communicate over a wireless network.

[0072] The user equipment 101 may support various communication modes, such as a connected mode (RRC connected), an inactive mode (RRC inactive), or an idle mode (RRC idle) defined by 3GPP. When operating in the RRC connected mode, the user equipment 101 is active and communicates with the base station 102. The user equipment 101 may transition from one communication mode to another using various commands and messages received from the base station 102. For example, the user equipment 101 may switch from the RRC connected state to the RRC inactive state upon receiving an RRC release message including a suspendConfig parameter.

[0073] When there is no traffic, the user equipment 101 can enter the RRC inactive state without completely releasing radio resources so as to quickly switch back to the RRC connected state when necessary. In this case, the user equipment and the base station can store a context (e.g., an access layer (AS) context) for the user equipment so as to apply the stored context when transitioning from the RRC inactive state to the RRC connected state, thereby reducing latency and signaling overhead. Such context may include radio configuration parameters such as uplink grants, RNTI (Radio Network Temporary Identifier), MCS, etc.

[0074] However, while the user equipment 101 is in the RRC inactive state, the radio conditions may have changed, for example the user equipment 101 may have moved to another location, and thus the channel quality changes.

[0075] Figure 2 is a simplified diagram showing an example of small data transmission terminated by a user equipment in an RRC inactive state according to an embodiment.

[0076] During preliminary step 200, the user equipment 101 may switch to the RRC inactive state in response to an RRC release message with a suspendConfig parameter. An I-RNTI (Inactive Radio Network Temporary Identifier) ​​may be allocated to the user equipment 101 as part of the suspendConfig parameter within such RRC release message.

[0077] When the user equipment 101 is in the RRC inactive state, the base station 102 may receive downlink data destined for the user equipment 101 at step 201. The downlink data may include a small amount of data such as keep-alive packets, sensor data, push notifications, location data, etc. The base station 102 may transmit a paging notification 202 to the user equipment 101 to inform the user equipment 101 of the available downlink data, the paging notification including at least an identifier associated with the user equipment 101, such as an I-RNTI.

[0078] At step 203, the user equipment 101 may receive a paging notification 202 while being inactive. The user equipment 101 may decode the received notification and compare at least one identifier (e.g., I-RNTI) associated with the user equipment 101 included in the notification with its own identifier to determine that the destination of the paging is the user equipment 101.

[0079] Receipt of such a paging notification by the user equipment 101 triggers at least a step of performing signal quality measurements 205. The signal quality measurements may include at least determining a reference signal received power (RSRP), a received signal strength indicator (RSSI), a reference signal received quality (RSRQ) and / or a channel quality indicator (CQI).

[0080] The user equipment 101 performs measurements based on SSB (synchronization signal block) resources and / or CSI-RS (channel state information reference signal) resources, whereby the SSB resources are broadcast through a system information message and the CSI-RS resources are configured through a system information message and / or a dedicated signaling message (e.g., a paging message or an RRC release message).

[0081] The user equipment 101 transmits the measurement report (eg CQI index) to the base station in a message 206. According to some embodiments, the message 206 may be of MsgA type or Msg3 type depending on the random access (RA) procedure type (two-step RA or four-step RA).

[0082] According to an embodiment, configuration grant (CG) resources are configured by the base station to the user equipment during the transition to the RRC inactive state, so that the UE uses these CG resources to directly transmit the CQI index to the gNB on the physical uplink shared channel (PUSCH) without performing 2-step RA and 4-step RA.

[0083] The present disclosure also contemplates that user equipment 101 may indicate one or more neighboring beams with / without CQI index in message 206. For example, user equipment 101 may provide one or more beam identifiers.

[0084] At step 207, the base station 102 may receive a message 206 including a CQI index. Based on the received CQI index, the base station 102 may determine during step 207 an appropriate MCS to transmit the pending data to the user equipment 101, i.e., for poor channel quality, a lower MCS is determined, and for good quality channels, a higher MCS is determined.

[0085] Table 1 below shows a mapping table defined by 3GPP, in which a CQI index is mapped to a specific modulation scheme.

[0086] CQI Index modulation 1 QPSK 2 QPSK 3 QPSK 4 QPSK 5 QPSK 6 QPSK 7 16QAM 8 16QAM 9 16QAM 10 64QAM 11 64QAM 12 64QAM 13 64QAM 14 64QAM 15 64QAM

[0087] Table 1

[0088] Base station 102 may use such a table to determine an appropriate MCS in response to a CQI index transmitted by user equipment 101 in message 206 .

[0089] The base station 208 may then send the downlink in a message 209 using the MCS determined at step 207. According to an embodiment, the message 209 may be of MsgB or Msg4 type depending on the random access procedure type (ie, 2-step or 4-step RA).

[0090] According to an embodiment, the base station 102 may replicate the downlink transmission in one or more neighboring beams when information about the one or more neighboring beams is provided in the message 206. Such a solution reduces the decoding error rate and increases reliability.

[0091] At step 210, user equipment 101 may receive downlink data in message 209. The downlink data is received using an MCS selected by base station 102 based on the CQI index transmitted by user equipment 101. Thus, high quality data transmission may occur even if radio channel conditions have changed after user equipment 101 entered the inactive state. This reduces the risk of retransmissions and allows energy saving.

[0092] Figure 3 is a simplified diagram showing an example of small data transmission terminated by a user equipment in an RRC inactive state according to the second embodiment.

[0093] like Figure 3 As shown, the second embodiment differs from the first embodiment in that the base station 102 performs step 203 of sending an initial small data burst immediately after sending the paging notification 202, and the initial small data burst is transmitted using a low MCS (e.g., QPSK). However, this initial low modulation and coding scheme can be dynamically updated by the user equipment 101 by sending a channel quality indicator through message 206 as described above. Such a provision allows robust and low latency data transmission.

[0094] Figure 4 is a block diagram showing a schematic architecture of an apparatus 500 suitable for implementing a wireless communication method for receiving a small data transmission (SDT) from a base station according to an embodiment.

[0095] The apparatus 500 comprises a processor 501 and a memory 502, such as a random access memory (RAM). The processor 501 may be controlled by a computer program 503 stored in the memory 502, the computer program comprising instructions configured to implement a method for receiving a small data transmission (SDT) from a base station in a wireless communication network.

[0096] More specifically, the computer program 503 comprises instructions for triggering a signal quality measurement upon receiving a paging notification from a base station in an inactive state; sending a message comprising at least a channel quality indication to the base station in response to the received paging notification; and receiving a message comprising downlink data from the base station, the message being transmitted using a modulation scheme selected by the base station based on the reported channel quality indication.

[0097] At initialization, the instructions of the computer program 503 may be loaded into the memory 502 before being executed by the processor 501. The processor 501 implements the steps of the method according to the instructions of the computer program 503.

[0098] The device 500 comprises a wireless communication unit 504, such as a 3G, 4G, 5G, 5GNR, WiFi or WiMax transceiver, for exchanging messages with other devices. In particular, the communication unit 504 is configured by program instructions to receive a paging notification broadcast by a base station and to check whether the received page is addressed to the device by comparing an identifier included in the paging notification with an identifier associated with the device.

[0099] The apparatus 500 further includes a radio channel quality measurement unit 505, which is configured to determine a reference signal received power (RSRP), a received signal strength indicator (RSSI), a reference signal received quality (RSRQ) and / or a channel quality indicator (CQI) based on an SSB (synchronization signal block) resource and / or a CSI-RS (channel state information reference signal). The measurement unit is further configured to report a channel quality indicator (such as a CQI index) to the base station in a message sent by the communication unit 504 (e.g., in MsgA, Msg3, or on a PUSCH).

[0100] The apparatus 500 further comprises a demodulator unit 506. The demodulator unit 506 is configured by program instructions to demodulate and decode the small data bursts received by the communication unit 504. In particular, the demodulator module 506 is configured to demodulate and decode the small data bursts transmitted in a message (e.g., in MsgB, Msg4 or via PDSCH) using a modulation scheme selected by the base station based on the channel quality indication determined by the measurement unit 505.

[0101] According to an embodiment, the apparatus 500 is included in a user device (eg, a cellular phone, a tablet, a vehicle, a smart sensor, etc.).

[0102] Figure 5is a block diagram showing a schematic architecture of an apparatus 600 suitable for implementing a wireless communication method for small data transmission (SDT) to a user equipment according to an embodiment.

[0103] The apparatus 600 comprises a processor 601 and a memory 602, such as a random access memory (RAM). The processor 601 may be controlled by a computer program 603 stored in the memory 602, the computer program comprising instructions configured to implement a method for performing small data transmission (SDT) to a user equipment in a wireless communication network.

[0104] More specifically, the computer program 603 comprises instructions for sending a paging notification to a user equipment when downlink data is available; receiving a response message to the paging notification, the message comprising at least a radio signal quality indicator measured by the user equipment; and transmitting a message comprising downlink data to the user equipment, the message being transmitted using a modulation scheme selected according to the received radio signal quality indicator.

[0105] At initialization, the instructions of the computer program 603 may be loaded into the memory 602 before being executed by the processor 601. The processor 601 implements the steps of the method according to the instructions of the computer program 603.

[0106] The apparatus 600 comprises a wireless communication unit 604, such as a 3G, 4G, 5G, 5GNR, WiFi or WiMax transceiver, for exchanging messages with other apparatuses. In particular, the communication unit 604 is configured by program instructions to broadcast a paging notification including at least an identifier of the user equipment when a small amount of data is to be transmitted to the user equipment in the RRC inactive state.

[0107] The wireless communication unit 604 is further configured by program instructions to receive a channel quality indicator (eg, CQI index) transmitted by the user equipment in MsgA or Msg3 or through the PUSCH in response to the paging notification.

[0108] The apparatus 600 further includes an MCS selection unit 605. The MCS selection unit can be configured by program instructions to select an MCS based on a channel quality indicator (e.g., a CQI index) received from the user equipment in response to a paging notification sent to the user equipment. The MCS selection unit is configured to select a low MCS for a low CQI index and a high MCS for a high CQI index. In some embodiments, the MCS selection unit can use a table similar to the table shown in Table 1 to select a specific MCS for a given CQI index.

[0109] The apparatus 600 further includes a modulation and coding unit 606 , which is configured by program instructions to encode and modulate the small data signal according to the MCS selected by the selection unit 605 .

[0110] According to an embodiment, the apparatus 600 is included in a base station (eg, an eNodeB or a gNodeB).

Claims

1. A method for receiving a small data transmission (SDT) from a base station in a wireless communication network, the method comprising the following actions: receiving (203) a paging notification (202) from a base station (102) in an inactive state (200), performing (205) a signal quality measurement, In response to the received paging notification (202), sending a message (206) including at least a channel quality indication report to the base station (102), and A message (209) comprising downlink data is received (210) from the base station (102), the message (209) being transmitted using a modulation scheme selected by the base station (102) based on the reported channel quality indication.

2. The method according to claim 1, wherein: The signal quality indication is reported in a msg3 message and the downlink data is received in a msg4 message.

3. The method according to claim 1, wherein: The signal quality indication is reported in a msgA message and the downlink data is received in a msgB message.

4. The method according to claim 1, wherein: The signal quality indication is reported on a physical uplink shared channel (PUSCH) using a resource grant configured by the base station prior to entering the RRC inactive state.

5. A method according to any one of the preceding claims, further comprising the step of receiving a message including initial downlink data from the base station before reporting the channel quality indication, wherein The initial downlink data is transmitted using a preconfigured low modulation scheme.

6. A method according to any one of the preceding claims, wherein: The message sent in response to the received paging notification further includes at least one neighbor beam indication.

7. An apparatus for receiving a small data transmission (SDT) from a base station in a wireless communication network, the apparatus comprising a processor (501) coupled to a memory (502) having computer program instructions (503) stored therein, the instructions being configured to perform the following actions when executed by the processor: Receive paging notifications from base stations in the inactive state, Perform signal quality measurements, sending a message including at least a channel quality indication report to the base station in response to the received paging notification, and A message including downlink data is received from the base station, the message being transmitted using a modulation scheme selected by the base station based on the reported channel quality indication.

8. A user equipment comprising the apparatus for receiving a small data transmission (SDT) according to claim 7.

9. A method for sending a small data transmission to a user equipment (101) in a wireless communication network, the method comprising: sending (201) a paging notification (202) to a user equipment (101), receiving (207) a response message (206) to the paging notification (202), the message (206) comprising at least a radio signal quality indicator report measured by the user equipment (101), A message (209) comprising downlink data is transmitted (208) to the user equipment (210), the message (209) being transmitted using a modulation scheme selected in dependence on the received radio signal quality indicator.

10. The method according to claim 9, wherein: The signal quality indicator is received in a msgA message and the downlink data is sent in a msgB message.

11. The method according to claim 9, wherein: The signal quality indicator is received in a msg3 message and the downlink data is sent in a msg4 message.

12. The method according to claim 9, wherein: The signal quality indicator is received on a physical uplink shared channel (PUSCH) using a resource grant configured prior to entering the RRC inactive state.

13. The method according to any one of claims 9 to 12, comprising: When the message received in response to the paging notification further includes at least one neighbor beam indication, the small data is transmitted on at least two beams.

14. An apparatus for transmitting a small data transmission (SDT) to a user equipment in a wireless communication network, the apparatus comprising a processor (601) coupled to a memory (602) having computer program instructions (603) stored therein, the instructions being configured to perform the following actions when executed by the processor: Sending a paging notification to the user equipment, receiving a response message to the paging notification, the message comprising at least a radio signal quality indicator report measured by the user equipment, A message including downlink data is transmitted to the user equipment, the message being transmitted using a modulation scheme selected according to the received radio signal quality indicator.

15. A base station comprising the apparatus for transmitting a small data transmission (SDT) according to claim 14.

16. A system for performing small data transmission in a wireless network comprising a base station and a user equipment, wherein: The base station comprises a processor coupled to a memory having computer program instructions stored therein, the instructions being configured to perform the following actions: sending a paging notification to the user equipment, receiving a response message to the paging notification, the message comprising at least a radio signal quality indicator report measured by the user equipment, transmitting a message including downlink data to the user equipment, the message being transmitted using a modulation scheme selected in accordance with the received radio signal quality indicator, and The user equipment comprises a processor coupled to a memory having computer program instructions stored therein, the instructions being configured to perform the following actions: Receive paging notifications from base stations in the inactive state, Perform signal quality measurements, sending a message including at least a channel quality indication report to the base station in response to the received paging notification, and A message including downlink data is received from the base station, the message being transmitted using a modulation scheme selected by the base station based on the reported channel quality indication.

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