PHYSICAL DOWNLINK CONTROL CHANNEL MONITORING FOR SMALL DATA TRANSMISSION PROCEDURE

Embodiments of the present disclosure relate to devices, methods, apparatuses and computer readable storage media of resource configuration for transmission of DMRS. The method comprises receiving, from a second device, information associated with a set of resources for monitoring a control channel between the first device and the second device for a Small Data Transmission (SDT) procedure, between the first device and the second device; monitoring the control channel based on the information; and performing the SDT based on a result of the monitoring procedure. In this way, the terminal device may determine a set of resources for the PDCCH monitoring for the SDT and therefore the blocking probability in the common search space can be avoid and the system efficiency can be improved.

FIELD

Embodiments of the present disclosure generally relate to the field of telecommunication and in particular to devices, methods, apparatuses and computer readable storage media of Physical Downlink Control Channel (PDCCH) monitoring for Small Data Transmission (SDT) procedure.

BACKGROUND

5G New Radio (NR) is the 5th generation mobile network. It is a new global wireless standard after 1G, 2G, 3G, and 4G networks. 5G enables a new kind of network that is designed to connect virtually everyone and everything together including machines, objects, and devices. 5G wireless technology is meant to deliver higher multi-Gbps peak data speeds, ultra-low latency, more reliability, massive network capacity, increased availability, and a more uniform user experience to more users. Higher performance and improved efficiency empower new user experiences and connects new industries.

The NR will support sending multiple Uplink (UL)/Downlink (DL) packets during the SDT procedure while not transitioning the User Equipment (UE) into a RRC_CONNECTED state in between nor performing separate SDT procedures for those transmissions. The SDT procedure in a RRC_INACTIVE state can be achieved based on a Random Access Channel (RACH) procedure or configured grant (CG).

SUMMARY

In general, example embodiments of the present disclosure provide a solution of PDCCH monitoring for SDT procedure.

In a first aspect, there is provided a first device. The first device comprises at least one processor; and at least one memory including computer program codes; the at least one memory and the computer program codes are configured to, with the at least one processor, cause the first device at least to receive, from a second device, information associated with a set of resources for monitoring a control channel between the first device and the second device for SDT procedure between the first device and the second device; monitor the control channel based on the information; and perform the SDT procedure based on a result of the monitoring procedure.

In a second aspect, there is provided a second device. The second device comprises at least one processor; and at least one memory including computer program codes; the at least one memory and the computer program codes are configured to, with the at least one processor, cause the second device at least to generate information associated with a set of resources for monitoring a control channel between the first device and the second device for a SDT procedure between the first device and the second device and transmit the information to the first device.

In a third aspect, there is provided a method. The method comprises receiving, from a second device, information associated with a set of resources for monitoring a control channel between the first device and the second device for a SDT procedure between the first device and the second device; monitoring the control channel based on the information; and performing the SDT procedure based on a result of the monitoring procedure.

In a fourth aspect, there is provided a method. The method comprises generating information associated with a set of resources for monitoring a control channel between the first device and the second device for a SDT procedure between the first device and the second device and transmitting the information to the first device.

In a fifth aspect, there is provided an apparatus comprising means for receiving, from a second device, information associated with a set of resources for monitoring a control channel between the first device and the second device for a SDT procedure between the first device and the second device; means for monitoring the control channel based on the information; and means for performing the SDT procedure based on a result of the monitoring procedure.

In a sixth aspect, there is provided an apparatus comprising means for generating information associated with a set of resources for monitoring a control channel between the first device and the second device for a SDT procedure between the first device and the second device and means for transmitting the information to the first device.

In a seventh aspect, there is provided a computer readable medium having a computer program stored thereon which, when executed by at least one processor of a device, causes the device to carry out the method according to the third aspect.

In an eighth aspect, there is provided a computer readable medium having a computer program stored thereon which, when executed by at least one processor of a device, causes the device to carry out the method according to the fourth aspect.

Other features and advantages of the embodiments of the present disclosure will also be apparent from the following description of specific embodiments when read in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of embodiments of the disclosure.

DETAILED DESCRIPTION

It shall be understood that although the terms “first” and “second” etc. may be used herein to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish functionalities of various elements. As used herein, the term “and/or” includes any and all combinations of one or more of the listed terms.

As used herein, the term “network device” refers to a node in a communication network via which a terminal device accesses the network and receives services therefrom. The network device may refer to a base station (BS) or an access point (AP), for example, a node B (NodeB or NB), an evolved NodeB (eNodeB or eNB), a NR Next Generation NodeB (gNB), a Remote Radio Unit (RRU), a radio header (RH), a remote radio head (RRH), a relay, a low power node such as a femto, a pico, and so forth, depending on the applied terminology and technology. A RAN split architecture comprises a gNB-CU (Centralized unit, hosting RRC, SDAP and PDCP) controlling a plurality of gNB-DUs (Distributed unit, hosting RLC, MAC and PHY). A relay node may correspond to DU part of the IAB node.

Although functionalities described herein can be performed, in various example embodiments, in a fixed and/or a wireless network node, in other example embodiments, functionalities may be implemented in a user equipment apparatus (such as a cell phone or tablet computer or laptop computer or desktop computer or mobile IoT device or fixed IoT device). This user equipment apparatus can, for example, be furnished with corresponding capabilities as described in connection with the fixed and/or the wireless network node(s), as appropriate. The user equipment apparatus may be the user equipment and/or or a control device, such as a chipset or processor, configured to control the user equipment when installed therein. Examples of such functionalities include the bootstrapping server function and/or the home subscriber server, which may be implemented in the user equipment apparatus by providing the user equipment apparatus with software configured to cause the user equipment apparatus to perform from the point of view of these functions/nodes.

FIG.1shows an example communication network100in which embodiments of the present disclosure can be implemented. As shown inFIG.1, the communication network100includes a terminal device110(hereinafter may also be referred to as a first device110or a UE110. The communication network100may comprise a network device120(hereinafter may also be referred to as a second device120or a gNB120). The network device120may communicate with the terminal device110.

It is to be understood that the number of terminal devices and network devices are only for the purpose of illustration without suggesting any limitations. The communication network100may include any suitable number of terminal devices adapted for implementing embodiments of the present disclosure.

Depending on the communication technologies, the network100may be a Code Division Multiple Access (CDMA) network, a Time Division Multiple Address (TDMA) network, a Frequency Division Multiple Access (FDMA) network, an Orthogonal Frequency-Division Multiple Access (OFDMA) network, a Single Carrier-Frequency Division Multiple Access (SC-FDMA) network or any others. Communications discussed in the network100may conform to any suitable standards including, but not limited to, New Radio Access (NR), Long Term Evolution (LTE), LTE-Evolution, LTE-Advanced (LTE-A), Wideband Code Division Multiple Access (WCDMA), Code Division Multiple Access (CDMA), cdma2000, and Global System for Mobile Communications (GSM) and the like. Furthermore, the communications may be performed according to any generation communication protocols either currently known or to be developed in the future. Examples of the communication protocols include, but not limited to, the first generation (1G), the second generation (2G), 2.5G, 2.75G, the third generation (3G), the fourth generation (4G), 4.5G, the fifth generation (5G) communication protocols. The techniques described herein may be used for the wireless networks and radio technologies mentioned above as well as other wireless networks and radio technologies. For clarity, certain aspects of the techniques are described below for LTE, and LTE terminology is used in much of the description below.

The RRC_INACTIVE state can be supported by NR and the UE with infrequent data transmission are generally maintained by the network in the RRC_INACTIVE state. Conventionally, the data transmission cannot be performed in the RRC_INACTIVE state. That is, the UE has to resume the connection (i.e. move to RRC_CONNECTED state) for any DL and UL data. For each data transmission, no matter how small and infrequent the data packets are, the connection setup and subsequently release to INACTIVE state must be performed, which may results in unnecessary power consumption and signalling overhead.

Signalling overhead from INACTIVE state UEs for small data packets is a general problem. In general, any device that has intermittent small data packets in INACTIVE state will benefit from enabling small data transmission in INACTIVE state. Therefore, in order to improve network performance and efficiency and the UE battery performance,

It has been proposed that the SDT in the RRC_INACTIVE state can be supported in NR. The 2-step, 4-step RACH and configured grant type-1 have already been specified for achieving the data transmission in the RRC_INACTIVE state.

For RACH based SDT, upon successful completion of contention resolution, the UE shall monitor the Cell-Radio Network Temporary Identifier (C-RNTI). For CG based SDT, the configuration of configured grant resource for UE uplink small data transmission can be contained in the RRCRelease message. The Configuration is only type 1 CG with no contention resolution procedure for CG.

Furthermore, for both RACH based SDT and CG based SDT, when the UE is in RRC_INACTIVE state, it should be possible to send multiple UL and DL packets as part of the same SDT mechanism and without transitioning to RRC_CONNECTED on dedicated grant.

For the RACH based SDT, it is to be discussed the configuration of the Control Resource Set (CORESET) and Search Space (SS) for monitoring the PDCCH addressed to the C-RNTI after successful completion of the RA procedure during RA-SDT. For CG based SDT, it is to be discussed the configuration of association between the type 1 CG resource(s) for CG-SDT and Synchronization Signal Block(s) (SSB(s)).

The PDCCH in NR carries Downlink Control Information (DCI). The DCI contains the scheduling information for the UL or DL data channels and other control information for one UE or a group of UEs. For the DCI payload bits, a 24-bit cyclic redundancy check (CRC) is calculated and appended to the payload. The CRC allows the UE to detect the presence of errors in the decoded DCI payload bits. After the CRC is attached, the last 16 CRC bits are masked with a corresponding identifier, which may referred to as a radio network temporary identifier (RNTI). Using the RNTI mask, the UE can detect the DCI for its unicast data and distinguish sets of DCI with different purposes that have the same payload size.

The payload bits of each DCI are separately scrambled by a scrambling sequence generated from the length-31Gold sequence. The scrambling sequence is initialized by the physical layer cell identity of the cell or by a UE specific scrambling identity and a UE specific C-RNTI. After the scrambled DCI bit sequence is Quadrature Phase Shift Keying (QPSK) modulated, the complex-valued modulation symbols are mapped to physical resources in units, which may be referred to as Control Channel Elements (CCEs).

Each CCE may consists of six Resource Element Groups (REGs), where a REG is defined as one Physical Resource Block (PRB) in one Orthogonal Frequency Division Multiplexing (OFDM) symbol which contains 9 Resource Elements (REs) for the PDCCH payload and 3 REs for Demodulation Reference Signal (DMRS). For each DCI, 1, 2, 4, 8, or 16 CCEs can be allocated, where the number of CCEs for a DCI is denoted as aggregation level (AL). Based on the channel environment and available resources, the gNB can adaptively choose a proper AL for a DCI to adjust the code rate.

A DCI with AL L can be mapped to physical resources in a given BandWidth Part (BWP), where necessary parameters such as frequency and time domain resources, and scrambling sequence identity for the DMRS for the PDCCH can be configured to a UE by means of CORESET. A UE may be configured with up to 3 CORESETs in Release 15 and up to 5 CORESETs in Release 16 on each of up to 4 BWPs on a serving cell.

The UE can perform blind decoding for a set of PDCCH candidates. The PDCCH candidates to be monitored are configured for a UE by means of SS sets. There are two SS set types, namely the common SS (CSS) set, which is commonly monitored by a group of UEs in a cell, and the UE-specific SS (USS) set, which is monitored by an individual UE.

A UE can be configured with up to 10 SS sets each for up to four BWPs in a serving cell. In general, the SS set configuration provides a UE with the SS set type, DCI format(s) to be monitored, monitoring occasion (periodicity, slot offset, duration in terms of successive slots), and the number of PDCCH candidates for each AL in the SS set.

The mapping of PDCCH candidates of an SS set to CCEs of the associated CORESET is implemented by means of a hash function. The hash function randomizes the allocation of the PDCCH candidates within CORESET. However, the hash function is not applied for any CSS set. That means that CCEs of PDCCHs are mapped to the same set of CCEs and thus they may block each other.

In this situation, when the first SDT transmission is performed, e.g., over 2-step or 4-step RACH, more data packets may come into UE's or network's buffer. The CSS and CORESET #0 will be generally used for network scheduling UE after the contention resolution. However, when UEs performing SDT have subsequent SDT data, scheduling such data may load the CSS/CORESET #0 such that less UEs can be served by the network. In other words, the same set of CCEs within the CORESET would need to be shared among CCS sets and SDT UEs. Consequence is the increased blocking probability which may be significant given high number of SDT UEs served.

The present disclosure provides solutions of PDCCH monitoring for SDT. In this solution. In this solution, the terminal device can obtain, from the network device, information associated with a PDCCH monitoring for the SDT between the terminal device and the network device. The terminal device then may monitor the PDCCH based on the information and perform the SDT based on a result of the PDCCH monitoring. In this way, the terminal device may determine a set of resources for the PDCCH monitoring for the SDT and therefore the blocking probability in the common search space can be avoid and the system efficiency can be improved.

Principle and implementations of the present disclosure will be described in detail as below with reference toFIG.2, which shows a schematic process of PDCCH monitoring for SDT. For the purpose of discussion, the process200will be described with reference toFIG.1. The process200may involve the UE110and the gNB120as illustrated inFIG.1.

As shown inFIG.2, the UE110may receive202, from the gNB120, information associated with a set of resources for monitoring a PDCCH between the UE110and the gNB120for a SDT procedure between the UE110and the gNB120.

In some example embodiments, the information can comprise a C-RNTI obtained from a RA procedure initiated for the SDT procedure. For example, in a RA procedure, the UE110may transmit a Message1 (MSG1) with a random access preamble to the gNB120. After receiving the MSG1 from the UE110, the gNB120may generate a random access response including a temporary-CRNTI (T-CRNTI) and transmit the random access response to the UE110as the Message2. After the contention solution is completed in the RA procedure, the T-CRNTI can be considered as the C-RNTI and used for scrambling the PDCCH in Message 4

In some example embodiments, the information can comprise a C-RNTI or other RNTI (e.g. SDT-RNTI) obtained from Configure Grant configuration allocated by the gNB120.

In some example embodiments, the UE110may determine the set of resources for monitoring a PDCCH between the UE110and the gNB120for the SDT procedure based on the C-RNTI.

When the UE is in a RRC_INACTIVE state, the UE may monitor the PDCCH in CSS sets for transmitting the small data packet. For example, the UE may determine mapping between the PDCCH of the CSS and the corresponding CCEs in a CORESET allowed to be used for monitoring the PDCCH based on the C-RNTI. For example, when the C-RNTI is obtained, the C-RNTI can be used for a hash operation for mapping the PDCCH of the CSS provided PDCCH monitoring for subsequent UL and/or DL SDT transmissions to the corresponding CCEs in the CORESET.

In some example embodiments, the UE110may determine, based on the C-RNTI, the set of resources for monitoring a PDCCH for the SDT procedure from a set of candidate resources allowed to be used for monitoring the PDCCH.

In some example embodiments, the set of resources can be considered as a SDT specific CSS set (e.g. Type4-PDCCH) which is associated to CORESET #0 and the UE can provided with such SDT specific CSS set. In some example embodiments, if the Type4-PDCCH is not provided to the UE, the UE may apply Type0-PDCCH CSS.

In some example embodiments, the UE110can also determine, based on the C-RNTI, the set of resources for monitoring a PDCCH for the SDT procedure on a new BWP which is different from an initial BWP. For example, the initial BWP can be a BWP on which the RA procedure is initiated. After completion of the SDT procedure, the CORESET/SS for the SDT procedure can be released and the UE can move back to original BWP.

In some example embodiments, it is also possible that the information comprises an explicit indication of the set of resources for monitoring a PDCCH between the UE110and the gNB120for the SDT procedure. The UE110may obtain the set of resources for monitoring a PDCCH for the SDT procedure from the indication.

After the set of resources for monitoring a PDCCH for the SDT procedure is determined based on the C-RNTI or an explicit indication, the UE110may monitor204the PDCCH on the set of resources.

In some example embodiments, the UE110can use the set of resources for monitoring a PDCCH for the SDT procedure upon completion of the RA procedure for SDT procedure, i.e., upon successful contention resolution and the RA procedure completion.

In some example embodiments, the UE110can also use the set of resources for monitoring a PDCCH for the SDT procedure during the RA procedure.

In some example embodiments, the UE110can also decode the set of candidate resources allowed to be used for monitoring the PDCCH, for example, the CSS/CORESET #0, if the set of candidate resources are within the same BWP as the SS/CORESET for SDT procedure. The corresponding priority can be configured for different resource sets. For example, in some example embodiments, the CSS/CORESET #0 may be prioritized over SS/CORESET for the SDT procedure. In some example embodiments, the SS/CORESET for the SDT procedure can be prioritized over CSS/CORESET #0.

After monitoring the PDCCH on the set of resources, the UE may detect the DCI from the resource and obtain UL grant for the SDT procedure and transmit206the small data packet on the UL grant in a RRC_INACTIVE state.

In this way, the terminal device may determine a set of resources for the PDCCH monitoring for the SDT procedure and therefore the blocking probability in the common search space can be avoid and the system efficiency can be improved.

FIG.3shows a flowchart of an example method300of PDCCH monitoring for SDT procedure according to some example embodiments of the present disclosure. The method300can be implemented at the first device110as shown inFIG.1. For the purpose of discussion, the method300will be described with reference toFIG.1.

At310, the first device receives, from a second device, information associated with a set of resources for monitoring a control channel between the first device and the second device for a SDT procedure between the first device and the second device.

In some example embodiments, the information can comprise a C-RNTI.

In some example embodiments, the information includes an indication of the set of resources for monitoring the control channel for the SDT procedure.

At320, the first device monitors the control channel based on the information.

In some example embodiments, the first device may obtain a C-RNTI from the information, the C-RNTI being allocated by the second device. The first device may further determine, based on the C-RNTI, the set of resources for monitoring the control channel for the SDT procedure from a set of candidate resources allowed to be used for monitoring the control channel and monitor the control channel on the set of resources.

In some example embodiments, the first device may obtain a C-RNTI from the information, the C-RNTI being allocated by the second device. The first device may further determine, based on the C-RNTI, the set of resources for monitoring the control channel for the SDT procedure on a new bandwidth part different than an initial bandwidth part and monitor the control channel on the set of resources.

In some example embodiments, the first device may obtain the C-RNTI from a RA procedure initiated for the SDT procedure or a configure grant allocated by the second device.

In some example embodiments, the set of resources may comprise a dedicated search space for monitoring the control channel for the SDT procedure or a common search space for monitoring the control channel for the SDT procedure.

In some example embodiments, the first device may monitor the control channel on the set of resources for monitoring the control channel for the SDT procedure after the RA procedure is completed.

In some example embodiments, the first device may monitor the control channel on the set of resources for monitoring the control channel for the SDT procedure during the RA procedure.

In some example embodiments, the first device may monitor the control channel on the set of candidate resources allowed to be used for monitoring the control channel, the set of candidate resources having a different priority from the set of resources.

In some example embodiments, the first device may obtain an indication of a set of resources for monitoring the control channel for the SDT procedure from the information and monitor the control channel on the set of resources.

At330, the first device performs the SDT procedure based on a result of the monitoring procedure.

In some example embodiments, the first device comprises a terminal device and the second device comprises a network device.

FIG.4shows a flowchart of an example method400of PDCCH monitoring for SDT procedure according to some example embodiments of the present disclosure. The method400can be implemented at the second device120as shown inFIG.1. For the purpose of discussion, the method400will be described with reference toFIG.1.

At410, the second device generates information associated with a set of resources for monitoring a control channel between the first device and the second device for a SDT procedure between the first device and the second device.

In some example embodiments, the information can comprise a C-RNTI.

In some example embodiments, the information includes an indication of the set of resources for monitoring the control channel for the SDT procedure.

At420, the second device transmits the information to the first device.

In some example embodiments, the first device comprises a terminal device and the second device comprises a network device.

In some example embodiments, an apparatus capable of performing the method300(for example, implemented at the first device110) may comprise means for performing the respective steps of the method300. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some example embodiments, the apparatus comprises means for receiving, from a second device, information associated with a set of resources for monitoring a control channel between the first device and the second device for a SDT procedure between the first device and the second device; means for monitoring the control channel based on the information; and means for performing the SDT procedure based on a result of the monitoring procedure.

In some example embodiments, the information can comprise a C-RNTI.

In some example embodiments, the information includes an indication of the set of resources for monitoring the control channel for the SDT procedure.

In some example embodiments, the means for monitoring the control channel comprises means for obtaining a C-RNTI from the information, the C-RNTI being allocated by the second device, means for determining, based on the C-RNTI, the set of resources for monitoring the control channel for the SDT procedure from a set of candidate resources allowed to be used for monitoring the control channel for the SDT procedure and means for monitoring the control channel on the set of resources for monitoring the control channel for the SDT procedure.

In some example embodiments, the means for monitoring the control channel comprises means for obtaining a C-RNTI from the information, the C-RNTI being allocated by the second device, means for determining, based on the C-RNTI, the set of resources for monitoring the control channel for the SDT procedure on a new bandwidth part different than an initial bandwidth part and means for monitoring the control channel on the set of resources for monitoring the control channel for the SDT procedure.

In some example embodiments, the means for obtaining the C-RNTI comprises means for obtaining the C-RNTI from a RA procedure initiated for the SDT procedure or a configure grant allocated by the second device.

In some example embodiments, the set of resources may comprise a dedicated search space for monitoring the control channel for the SDT procedure or a common search space for monitoring the control channel for the SDT procedure.

In some example embodiments, the means for monitoring the control channel on the set of resources for monitoring the control channel for the SDT procedure comprises means for monitoring the control channel on the set of resources for monitoring the control channel for the SDT procedure after the RA procedure is completed.

In some example embodiments, the means for monitoring the control channel on the set of resources for monitoring the control channel for the SDT procedure comprises means for monitoring the control channel on the set of resources for monitoring the control channel for the SDT procedure during the RA procedure.

In some example embodiments, the apparatus also comprises means for monitoring the control channel on the set of candidate resources allowed to be used for monitoring the control channel, the set of candidate resources having a different priority from the set of resources.

In some example embodiments, the means for monitoring the control channel comprises means for obtaining an indication of a set of resources for monitoring the control channel for the SDT procedure from the information and means for monitoring the control channel on the set of resources.

In some example embodiments, the first device comprises a terminal device and the second device comprises a network device.

In some example embodiments, an apparatus capable of performing the method400(for example, implemented at the second device120) may comprise means for performing the respective steps of the method400. The means may be implemented in any suitable form. For example, the means may be implemented in a circuitry or software module.

In some example embodiments, the apparatus comprises means for generating information associated with a set of resources for monitoring a control channel between the first device and the second device for a SDT procedure between the first device and the second device and means for transmitting the information to the first device.

In some example embodiments, the information can comprise a C-RNTI.

In some example embodiments, the information includes an indication of the set of resources for monitoring the control channel for the SDT procedure.

In some example embodiments, the first device comprises a terminal device and the second device comprises a network device.

FIG.5is a simplified block diagram of a device500that is suitable for implementing embodiments of the present disclosure. The device500may be provided to implement the communication device, for example the UE110or the gNB120as shown inFIG.1. As shown, the device500includes one or more processors510, one or more memories520coupled to the processor510, and one or more transmitters and receivers (TX/RX)540coupled to the processor510.

The TX/RX540is for bidirectional communications. The TX/RX540has at least one antenna to facilitate communication. The communication interface may represent any interface that is necessary for communication with other network elements.

A computer program530includes computer executable instructions that are executed by the associated processor510. The program530may be stored in the ROM520. The processor510may perform any suitable actions and processing by loading the program530into the RAM520.

The embodiments of the present disclosure may be implemented by means of the program530so that the device500may perform any process of the disclosure as discussed with reference toFIGS.2-4. The embodiments of the present disclosure may also be implemented by hardware or by a combination of software and hardware.

In some embodiments, the program530may be tangibly contained in a computer readable medium which may be included in the device500(such as in the memory520) or other storage devices that are accessible by the device500. The device500may load the program530from the computer readable medium to the RAM522for execution. The computer readable medium may include any types of tangible non-volatile storage, such as ROM, EPROM, a flash memory, a hard disk, CD, DVD, and the like.FIG.6shows an example of the computer readable medium600in form of CD or DVD. The computer readable medium has the program530stored thereon.