User equipment and base station

Abstract

The present disclosure relates to a user equipment (UE) comprising the following. A processor of the UE runs a monitoring function involving monitoring a downlink control channel for receiving a downlink control information message based on one of a plurality of search space set groups. A receiver of the UE receives the downlink control information message via the monitored downlink control channel, wherein the received downlink control information message allocates transmission or reception of data to the UE. The processor further determines the one of the plurality of search space set groups for performing the monitoring function of the downlink control channel. The determination of the group of search space sets is based on content or format of the received downlink control information message.

Description

TECHNICAL FIELD

[0001] The present disclosure is directed to methods, devices, and articles of manufacture in a communication system, such as a 3GPP communication system. TECHNICAL BACKGROUND

[0002] Currently, the Third Generation Partnership Project (3GPP) is working on technical specifications for the next generation of cellular technology, also referred to as the fifth generation (5G).

[0003] One goal is to provide a single technical framework addressing all usage scenarios, requirements and deployment scenarios (see, e.g., Section 6 of TR 38.913 version 15.0.0), including at least enhanced mobile broadband (eMBB), ultra-reliable low-latency communications (URLLC), massive machine-type communications (mMTC). For example, eMBB deployment scenarios can include indoor hot spot, dense urban, rural, urban macro, and high speed; URLLC deployment scenarios can include industrial control, mobile health care (remote

[0004] A second goal is to enable forward compatibility. There is no requirement for backward compatibility with Long Term Evolution (LTE, LTE-A) cellular systems, which facilitates the design of a completely new system and / or the introduction of novel features. SUMMARY

[0005] One non-limiting and exemplary embodiment facilitates providing a procedure for facilitating a UE to perform an improved downlink control channel monitoring procedure.

[0006] In an embodiment, the technology disclosed herein features a user equipment comprising the following. A processor of the UE executes a monitoring function involving monitoring a downlink control channel for receiving a downlink control information message based on one of a plurality of search space set groups. A receiver of the UE receives the downlink control information message via the monitored downlink control channel, wherein the received downlink control information message allocates transmission or reception of data to the UE. The processor further determines one of the plurality of search space set groups for performing the monitoring function of the downlink control channel. The determination of the one search space set group is based on:

[0007] • a content or format of the received downlink control information message.

[0008] It should be noted that a general or specific embodiment can be implemented as a system, a method, an integrated circuit, a computer program, a storage medium, or any selective combination thereof. For example, an integrated circuit can control the procedure of a UE or a base station.

[0009] Additional benefits and advantages of the disclosed embodiments and variations will be apparent from the description and drawings. These benefits and / or advantages can be obtained by means that are separate from those specifically described, and need not be obtained in connection with each and every implementation of the embodiments and variations. Accordingly, the embodiments and variations are not limited to only those implementations described and illustrated herein. BRIEF DESCRIPTION OF DRAWINGS

[0010] In the following, exemplary embodiments will be described in more detail with reference to the accompanying drawings.

[0011] Figure 1 An exemplary architecture of a 3GPP NR system is shown;

[0012] Figure 2 is a schematic diagram showing the functional split between NG-RAN and 5GC,

[0013] Figure 3 is a sequence diagram of the RRC connection establishment / reconfiguration procedure,

[0014] Figure 4 is a diagram showing the usage scenarios of enhanced mobile broadband (eMBB), massive machine type communications (mMTC), and ultra-reliable and low-latency communications (URLLC),

[0015] Figure 5 is a block diagram showing an exemplary 5G system architecture for a non-roaming scenario,

[0016] Figure 6 The relationship between different bandwidth parts, CORESETs, search spaces, and PDCCH candidates is shown;

[0017] Figure 7 The configuration of search space sets in different SSS groups is shown,

[0018] Figure 8A and 8B The switching between two search space set groups is shown according to an exemplary 5G NR standard implementation,

[0019] Figure 9 A 5G NR frame structure is shown, including frames, subframes, slots, OFDM symbols, and mini-slots,

[0020] Figure 10 An exemplary multi-TTI scheduling is shown, where two PDSCH receptions are allocated by a single DCI,

[0021] Figure 11 Issues related to multi-TTI scheduling and PDCCH monitoring are shown,

[0022] Figure 12 Exemplary and simplified structures of a UE and a gNB are shown,

[0023] Figure 13 Structure of a UE according to an exemplary embodiment of the improved PDCCH monitoring procedure is shown,

[0024] Figure 14 is a flow chart of UE behavior according to an exemplary embodiment of the improved PDCCH monitoring procedure,

[0025] Figure 15 Structure of a base station according to an exemplary embodiment of the improved PDCCH monitoring procedure is shown,

[0026] Figure 16 is a flow chart of base station behavior according to an exemplary embodiment of the improved PDCCH monitoring procedure,

[0027] Figure 17 Switching between different search space set groups according to the improved PDCCH monitoring procedure is shown,

[0028] Figure 18 is a flow chart of UE behavior according to a first solution of the improved PDCCH monitoring procedure,

[0029] Figure 19 and 20 is a diagram showing switching between different search space set groups according to a first solution of the improved PDCCH monitoring procedure,

[0030] Figure 21 is a flow chart of UE behavior according to a variant of the first solution of the improved PDCCH monitoring procedure,

[0031] Figure 22 and 23 is a state change diagram of a UE according to the first solution of the improved PDCCH monitoring procedure,

[0032] Figure 24 is a flow chart of UE behavior according to a second solution of the improved PDCCH monitoring procedure,

[0033] Figure 25 is a flow chart of UE behavior according to a variant of the second solution of the improved PDCCH monitoring procedure,

[0034] Figure 26 is a state change diagram of a UE according to a variant of the second solution of the improved PDCCH monitoring procedure, and

[0035] Figure 27 is a flowchart of the UE behavior according to a third solution of the improved PDCCH monitoring procedure. DETAILED DESCRIPTION

[0036] 5G NR system architecture and protocol stack

[0037] 3GPP has been working on the release of the next version of the fifth generation cellular technology, simply referred to as 5G, including the development of a new radio access technology (NR) working in frequency ranges up to 100 GHz. The first release of the 5G standard was completed at the end of 2017, which allowed for the trial and commercial deployment of smartphones compliant with the 5G NR standard.

[0038] The overall system architecture employs, among others, an NG-RAN (Next Generation Radio Access Network) comprising gNBs, providing the UE with NG-Radio Access User Plane (SDAP / PDCP / RLC / MAC / PHY) and Control Plane (RRC) protocol terminations. gNBs are connected among each other by means of the Xn interface. gNBs are also connected by means of the Next Generation (NG) interface to the NGC (Next Generation Core), more specifically to the AMF (Access and Mobility Management Function) by means of the NG-C interface (e.g. a concrete core entity performing the AMF) and to the UPF (User Plane Function) by means of the NG-U interface (e.g. a concrete core entity performing the UPF). Figure 1 Fig. 1 illustrates the NG-RAN architecture (see e.g. 3GPP TS 38.300 v16.0.0, section 4).

[0039] The user plane protocol stack for NR (see e.g. 3GPP TS 38.300, section 4.4.1) includes the PDCP (Packet Data Convergence Protocol, see section 6.4 of TS 38.300), RLC (Radio Link Control, see section 6.3 of TS 38.300) and MAC (Medium Access Control, see section 6.2 of TS 38.300) sub-layers, which are terminated in the gNB on the network side. Additionally, a new Access Stratum (AS) sub-layer (SDAP, Service Data Adaptation Protocol) is introduced on top of PDCP (see e.g. subclause 6.5 of 3GPP TS 38.300). A control plane protocol stack is also defined for NR (see e.g. section 4.4.2 of TS 38.300). An overview of the layer 2 functionality is given in subclause 6 of TS 38.300. The functionality of the RRC layer is listed in subclause 7 of TS 38.300.

[0040] For example, the medium access control layer handles logical channel multiplexing, scheduling and scheduling-related functionality, including handling of different priority levels.

[0041] The physical layer (PHY) is, for example, responsible for encoding, PHY HARQ processing, modulation, multi-antenna processing, and mapping of signals onto the appropriate physical time-frequency resources. It also handles the mapping of transport channels to physical channels. The physical layer provides services to the MAC layer in the form of transport channels. A physical channel corresponds to a set of time-frequency resources used for transmission of a particular transport channel, and each transport channel is mapped to a corresponding physical channel. For example, the physical channels are PRACH (Physical Random Access Channel), PUSCH (Physical Uplink Shared Channel) and PUCCH (Physical Uplink Control Channel) for the uplink and PDSCH (Physical Downlink Shared Channel), PDCCH (Physical Downlink Control Channel) and PBCH (Physical Broadcast Channel) for the downlink.

[0042] Use cases / deployment scenarios for NR can include enhanced mobile broadband (eMBB), ultra-reliable low-latency Communication (URLLC), massive Machine Type Communication (mMTC), which have different requirements in terms of data rate, latency and coverage. For example, eMBB is expected to support peak data rates (20 Gbps for the downlink and 10 Gbps for the uplink) and user-experienced data rates that are three orders of magnitude larger than what is offered by IMT-Advanced. On the other hand, in the case of URLLC, more stringent requirements are placed on ultra-low latency (0.5 ms for user plane latency for both UL and DL) and high reliability (1-10-5 within 1 ms). Finally, mMTC can preferably require high connection density (1,000,000 devices / km2 in urban areas), large coverage in poor environments, and extremely long battery life for low-cost devices (15 years).

[0043] Thus, an OFDM numerology (e.g., subcarrier spacing, OFDM symbol duration, cyclic prefix (CP) duration, number of symbols per scheduling interval) that is suitable for one use case can not be suitable for another use case. For example, a low latency service can prefer a shorter symbol duration (and thus a larger subcarrier spacing) and / or fewer symbols per scheduling interval (also referred to as TTI) compared to an mMTC service. Furthermore, a deployment scenario with large channel delay spread can prefer a longer CP duration compared to a deployment scenario with short delay spread. The subcarrier spacing should be optimized accordingly to preserve similar CP overhead. NR can support more than one subcarrier spacing value. Correspondingly, subcarrier spacing 15 kHz, 30 kHz, 60 kHz,... are currently under consideration. The symbol duration Tuand the subcarrier spacing Af are directly related by the formula Af = 1 / Tu. In a similar way as in the LTE system, the term "resource element" can be used to refer to the smallest resource unit consisting of one subcarrier for the duration of one OFDM / SC-FDMA symbol length.

[0044] In the new radio system 5G-NR, for each numerology and carrier, a resource grid of subcarriers and OFDM symbols is defined for the uplink and downlink, respectively. Each element in the resource grid is referred to as a resource element and is identified based on a frequency index in the frequency domain and a symbol position in the time domain (see 3GPP TS 38.211 v16.0.0, e.g., Section 4). For example, downlink and uplink transmissions are organized into frames with a duration of 10 ms, each frame consisting of 10 subframes with a duration of 1 ms each. In an embodiment of 5G-NR, the number of consecutive OFDM symbols per subframe depends on the subcarrier spacing configuration. For example, for a subcarrier spacing of 15 kHz, a subframe has 14 OFDM symbols (similar to LTE-compliant embodiments, assuming a normal cyclic prefix). On the other hand, for a subcarrier spacing of 30 kHz, a subframe has two slots, each containing 14 OFDM symbols.

[0045] Function split between NG-RAN and 5GC

[0046] Figure 2 The function split between NG-RAN and 5GC is illustrated. The NG-RAN logical nodes are gNBs or ng-eNBs. The 5GC has the logical nodes AMF, UPF, and SMF.

[0047] In particular, the gNBs and ng-eNBs host the following main functions:

[0048] - Functions for radio resource management, such as radio bearer control, radio access control, connection mobility control, and dynamic allocation (scheduling) of resources to the UE in both uplink and downlink;

[0049] - Data IP header compression, encryption, and data integrity protection;

[0050] - When a route to the AMF cannot be determined from the information provided by the UE, the AMF is selected at the UE attachment point;

[0051] - Routing of user plane data to (one or more) UPFs;

[0052] - Routing of control plane information to AMF;

[0053] - Connection establishment and release;

[0054] - Scheduling and sending paging messages;

[0055] - Scheduling and sending of system broadcast messages (originating from AMF or OAM);

[0056] - Configuration for measurement and measurement reporting for mobility and scheduling;

[0057] -Transmission-level packet markings in the uplink;

[0058] -Session management;

[0059] -Support for network slicing;

[0060] - QoS flow management and mapping to data radio bearers;

[0061] - Support for UEs in RRC_INACTIVE state;

[0062] -NAS message distribution functionality;

[0063] - Radio access network sharing;

[0064] - Dual connectivity;

[0065] -Close interoperability between NR and E-UTRA.

[0066] The Access and Mobility Management Function (AMF) hosts the following key functions:

[0067] -Non-access hierarchical NAS signaling terminal;

[0068] -NAS signaling security;

[0069] -Access layered AS security control;

[0070] - Core network (CN) inter-node signaling for mobility between 3GPP access networks;

[0071] - Idle mode UE reachability (including control and operation of paging retransmission);

[0072] -Registration area management;

[0073] - Support for mobility within and between systems;

[0074] -Access authentication;

[0075] - Access authorization, including checking roaming permissions;

[0076] - Mobility management controls (subscriptions and policies);

[0077] -Support for network slicing;

[0078] -Session Management Function (SMF) selection.

[0079] In addition, the User Plane Function UPF hosts the following main functions:

[0080] - Anchor points for movement within / between RATs (where applicable);

[0081] - External PDU session points that interconnect with the data network;

[0082] - Packet routing and forwarding;

[0083] - User plane section for group checks and policy rule enforcement;

[0084] - Traffic usage report;

[0085] -Supports uplink classifiers that route traffic streams to the data network;

[0086] -Supports branching points for multi-host PDU sessions;

[0087] - QoS handling for the user plane, such as packet filtering, gating, and UL / DL rate enforcement;

[0088] - Uplink traffic verification (SDF to QoS flow mapping);

[0089] - Downlink packet buffering and downlink data notification triggering.

[0090] Finally, the session management function SMF hosts the following main functions:

[0091] -Session management;

[0092] -UE IP address allocation and management;

[0093] -Selection and control of UP function;

[0094] - Configure traffic routing at the User Plane Function (UPF) to route traffic to the appropriate destination;

[0095] - The control portion and QoS for policy enforcement;

[0096] - Downlink data notification.

[0097] RRC connection establishment and reconfiguration procedure

[0098] Figure 3 The diagram illustrates some interactions between the NAS section (see TS 38.300) and the UE, gNB, and AMF (5GC entity) in the context of the UE transitioning from RRC_IDLE to RRC_CONNECTED.

[0099] RRC is a higher-level signaling (protocol) used for UE and gNB configuration. Specifically, this transition involves the AMF preparing UE context data (including, for example, PDU session context, security keys, UE radio capabilities, and UE security capabilities) and sending it to the gNB along with an initial context establishment request. The gNB then activates AS security with the UE, which is performed by the gNB sending a SecurityModeCommand message to the UE and by the UE responding to the gNB with a SecurityModeComplete message. The gNB then performs reconfiguration to establish signaling radio bearer 2, SRB2, and (one or more) data radio bearers DRB(s) by sending an RRCReconfiguration message to the UE and receiving an RRCReconfigurationComplete message from the UE in response. For signaling-only connections, the steps related to RRCReconfiguration are skipped because SRB2 and DRB are not established. Finally, the gNB notifies the AMF that the establishment procedure is complete via an initial context establishment response.

[0100] Therefore, this disclosure provides a fifth-generation (5GC) core entity (e.g., AMF, SMF, etc.) including a control circuit that establishes a next-generation (NG) connection with the gNodeB; and a transmitter that sends an initial context establishment message to the gNodeB via the NG connection to initiate the establishment of a signaling radio bearer between the gNodeB and the user equipment (UE). Specifically, the gNodeB sends radio resource control (RRC) signaling containing resource allocation configuration information elements (IEs) to the UE via the signaling radio bearer. The UE then performs uplink transmission or downlink reception based on the resource allocation configuration.

[0101] Use cases of IMT in 2020 and beyond

[0102] Figure 4 The illustrations depict some use cases for 5G NR. Within the 3rd Generation Partnership Project New Radio (3GPP NR), three use cases under consideration have been envisioned to support a wide variety of services and applications by IMT-2020. The Phase 1 specification for Enhanced Mobile Broadband (eMBB) has been completed. In addition to further extending eMBB support, current and future work will involve the standardization of Ultra Reliable and Low Latency Communications (URLLC) and Massive Machine-Type Communications. Figure 4 The illustrations show some examples of envisioned use cases for IMT in 2020 and beyond (see example). Figure 2 (ITU-R M.20183).

[0103] URLLC use cases have stringent requirements for capabilities such as throughput, latency, and availability, and are envisioned as one of the driving forces for future vertical applications such as wireless control of industrial manufacturing or production processes, telemedicine surgery, distribution automation in smart grids, and transmission security. Ultra-reliability of URLLC is supported by identifying technologies that meet the set of requirements of TR 38.913 version 15.0.0. For NR URLLC in version 15, key requirements include a target user plane latency of 0.5ms for both UL (uplink) and DL (downlink). For a 32-byte packet size with a 1ms user plane latency, the typical URLLC requirement for a single packet transmission is a BLER (Block Error Rate) of 1E-5.

[0104] From a physical layer perspective, reliability can be improved in a variety of ways. Current reliability improvements include defining a separate CQI table for URLLC, a more compact DCI format, and PDCCH repetition. However, as NR becomes more stable and advanced, the scope for achieving ultra-reliability may expand (for NR URLLC critical requirements). Specific use cases for NR URLCC in Rel.15 include augmented reality / virtual reality (AR / VR), e-health, e-security, and mission-critical applications.

[0105] Furthermore, the technical enhancements targeted by NR URLCC aim to improve latency and reliability. Latency enhancements include: configurable parameter sets, non-slot-based scheduling with flexible mapping, unlicensed (configured-licensed) uplinks, slot-level repetition of data channels, and downlink preemption. Preemption means that a transmission for which resources have already been allocated is stopped, and the allocated resources are used for another transmission that is requested later but has lower latency / higher priority requirements. Accordingly, a licensed transmission is preempted by a later transmission. The applicability of preemption is independent of the specific service type. For example, a transmission of service type A (URLCC) may be preempted by a transmission of service type B (such as eMBB). Reliability enhancements include a dedicated CQI / MCS table for the target BLER of 1E-5.

[0106] The use cases for mMTC (massive machine-type communication) are characterized by a large number of connected devices typically sending relatively small amounts of non-latency-sensitive data. Devices are required to be low-cost and have very long battery life. From an NR (Radio Frequency Identification) perspective, utilizing a very narrow bandwidth segment is a possible solution to save power (from the UE's perspective) and enable long battery life.

[0107] As mentioned above, the scope of reliability in NR is expected to become broader. A key requirement for all cases (and especially for URLLC and mMTC) is high or ultra-reliability. Several mechanisms can be considered to improve reliability from both radio and network perspectives. Generally, there are several key potential areas that can help improve reliability. These areas include compact control channel information, data / control channel repetition, and diversity relative to the frequency, time, and / or spatial domains. These areas apply to general reliability regardless of the specific communication scenario.

[0108] For NR URLLC, other use cases with more stringent requirements have been identified, such as factory automation, the transportation industry, and power distribution. More stringent requirements mean higher reliability (up to 10). 6 (Level), higher availability, packet size up to 256 bytes, time synchronization down to a few microseconds (where the value can be one or several microseconds, depending on the frequency range), and short latency in the range of 0.5 to 1 millisecond, specifically 0.5 milliseconds of target user plane latency, depending on the use case.

[0109] Furthermore, for NR URLCC, several technical enhancements have been identified from a physical layer perspective. These include PDCCH (Physical Downlink Control Channel) enhancements, which are associated with compact DCI, PDCCH repetition, and increased PDCCH monitoring. Additionally, UCI (Uplink Control Information) enhancements are associated with enhanced HARQ (Hybrid Automatic Repeat Request) and CSI feedback enhancements. PUSCH enhancements related to micro-slot-level hopping and retransmission / repetition enhancements have also been identified. The term "micro-slot" refers to a transmission time interval (TTI) that includes fewer symbols than a time slot (a time slot consisting of 14 symbols).

[0110] QoS control

[0111] The 5G QoS (Quality of Service) model is based on QoS flows and supports both QoS flows that require guaranteed flow bit rate (GBR QoS flows) and QoS flows that do not require guaranteed flow bit rate (non-GBR QoS flows). Therefore, at the NAS level, QoS flows represent the finest QoS granularity within a PDU session. QoS flows are identified within a PDU session by the QoS Flow ID (QFI) carried in the encapsulation header on the NG-U interface.

[0112] For each UE, 5GC establishes one or more PDU sessions. For each UE, NG-RAN establishes at least one data radio bearer (DRB) along with the PDU session, and subsequently, one or more additional DRBs for the QoS flows of that PDU session can be configured (when to do so depends on NG-RAN), as shown in the reference above. Figure 4 As shown, NG-RAN maps packets belonging to different PDU sessions to different DRBs. NAS-level packet filters in the UE and 5GC associate UL and DL packets with QoS flows, while AS-level mapping rules in the UE and NG-RAN associate UL and DL QoS flows with DRBs.

[0113] Figure 5 The diagram illustrates a 5G NR non-roaming reference architecture (see TS 23.501 v16.3.0, Section 4.2.3). Application Functions (AFs) (e.g.) Figure 4 The external application server (exemplarily described in the example) hosting 5G services interacts with the 3GPP core network to provide services, such as supporting application-level influence on traffic routing, access network open functions (NEF), or interacting with policy frameworks used for policy control (see Policy Control Functions, PCF), such as QoS control. Based on operator deployment, operator-trusted application functions may be allowed to interact directly with relevant network functions. Application functions that the operator does not allow to directly access network functions interact with relevant network functions via the NEF using an external open framework.

[0114] Figure 5 The diagram illustrates further functional units of the 5G architecture, namely Network Slice Selection Function (NSSF), Network Repository Function (NRF), Unified Data Management (UDM), Authentication Server Function (AUSF), Access and Mobility Management Function (AMF), Session Management Function (SMF), and Data Network (DN), such as operator services, internet access, or third-party services. All or part of the core network functions and application services can be deployed and run on a cloud computing environment.

[0115] Therefore, this disclosure provides an application server (e.g., an AF in a 5G architecture) including a transmitter that sends a request containing QoS requirements for at least one of URLLC, eMBB, and mMTC services to at least one function in the 5GC (e.g., NEF, AMF, SMF, PCF, UPF, etc.) to establish a PDU session including a radio bearer between a gNodeB and a UE according to the QoS requirements and a control circuit that performs services using the established PDU session.

[0116] Bandwidth section

[0117] The NR system will support a much wider maximum channel bandwidth (e.g., 100MHz) than LTE's 20MHz. In LTE, wideband communication is also supported via carrier aggregation (CA) of component carriers up to 20MHz. By defining a wider channel bandwidth in NR, frequency resources can be dynamically allocated via scheduling, which is more efficient and flexible than LTE's carrier aggregation operation, whose activation / deactivation is based on MAC control elements. Having a single wideband carrier also has the advantage of low control overhead, as it requires only a single control signaling (carrier aggregation requires separate control signaling for each aggregated carrier).

[0118] In addition, similar to LTE, NR can also support the aggregation of multiple carriers via carrier aggregation or dual connectivity.

[0119] Because UEs don't always require high data rates, the use of wide bandwidth can result in higher idle power from both RF and baseband signal processing perspectives. In this regard, the newly developed concept of bandwidth portion for NR provides a way to operate the UE using a smaller bandwidth than the configured channel bandwidth, thus offering an energy-efficient solution while still supporting wideband operation. Low-end terminals that cannot access the full bandwidth for NR can benefit from this.

[0120] A bandwidth portion (BWP) is a subset of the total cell bandwidth, such as the location and number of adjacent physical resource blocks (PRBs). It can be defined separately for uplink and downlink. Furthermore, each bandwidth portion can be associated with a specific set of OFDM parameters, such as subcarrier spacing and cyclic prefix. For example, bandwidth adaptation is achieved by configuring the UE using BWPs and informing the UE which of the configured BWPs is currently active.

[0121] For example, in 5G NR, specific BWPs are configured only for UEs in the RRC_Connected state. For instance, aside from the initial BWP (e.g., one for UL and one for DL ​​respectively), the BWPs only exist for UEs in the connected state. To support initial data exchange between the UE and the network, for example, during the process of moving the UE from the RRC_IDLE or RRC_INACTIVE state to the RRC_CONNECTED state, the initial DL BWP and initial UL BWP are configured in the minimal system information.

[0122] Although a UE can be configured with more than one BWP (e.g., up to 4 BWPs per serving cell, as currently defined for NR), a UE can only have one active DL BWP at a time.

[0123] For example, switching between configured BWPs can be achieved through downlink control information (DCI).

[0124] For the primary cell (PCell), the initial BWP is the BWP used for initial access, and the default BWP is the initial BWP unless another initial BWP is explicitly configured. For the secondary cell (SCell), the initial BWP is always explicitly configured, and a default BWP can also be configured. When the default BWP is configured for the serving cell, the expiration of the inactivity timer associated with that cell switches the active BWP to the default BWP.

[0125] Some DCI formats do not include a BWP ID (e.g., formats 0_0 and 1_0), however, in other DCI formats, the number of bits used for the BWP ID is RRC-configurable and can be 0, 1, or 2 bits (e.g., formats 0_1, 0_2, 1_1, and 1_2).

[0126] Figure 6 The diagram shows three different BWP configurations: BWP1 with a frequency bandwidth of 40 MHz and a subcarrier spacing of 15 kHz, BWP2 with a frequency bandwidth of 10 MHz and a subcarrier spacing of 15 kHz, and BWP3 with a frequency bandwidth of 20 MHz and a subcarrier spacing of 60 kHz.

[0127] Control information - search space set

[0128] The UE performs PDCCH monitoring in order to identify and receive information for the UE's purposes, such as control information and user traffic (e.g., DCI on the PDCCH and user data on the PDSCH indicated by the PDCCH).

[0129] Downlink control information (which may be referred to as downlink control information, DCI) serves essentially the same purpose in 5G NR as DCI in LTE, namely, as a special set of control information for scheduling, for example, downlink data channels (e.g., PDSCH) or uplink data channels (e.g., PUSCH). Several different DCI formats have been defined in 5G NR (see Section 7.3.1 of TS 38.212 v16.0.0). An overview is provided in the table below.

[0130]

[0131] In 5G NR, the PDCCH is transmitted in a radio resource area called the Control Resource Set (CORESET). In LTE, the concept of CORESET is not explicitly presented. Instead, the PDCCH in LTE uses the full carrier bandwidth (4 for the narrowest band) over the first 1-3 OFDM symbols. In contrast, CORESET in NR can occur anywhere within a time slot and anywhere within the carrier's frequency range, unless the UE does not expect to process CORESET outside its Active Bandwidth Part (BWP).

[0132] Therefore, the UE uses the corresponding search space set to monitor one or more PDCCH candidate sets in one CORESET on each active serving cell configured with PDCCH monitoring, wherein the monitoring implies decoding each PDCCH candidate according to the monitored DCI format, for example, as defined in 3GPP TS 38.213 Release 16.1.0, Sections 10 and 11.

[0133] In an exemplary 5G NR implementation, the search space may include multiple PDCCH candidates associated with the same aggregation level (e.g., where the PDCCH candidates differ in terms of the DCI format to be monitored). Furthermore, the search space set may include multiple search spaces at different aggregation levels, but associated with the same CORESET. Unlike LTE, where the control channel spans the entire carrier bandwidth as described above, the bandwidth of the CORESET can be configured, for example, within the active DL frequency bandwidth portion (BWP). In other words, the CORESET configuration defines the frequency resources for the included PDCCH candidates used for the search space set and therefore for the search spaces within the set. The CORESET configuration also defines the duration of the search space set, which can have a length of one to three OFDM symbols. On the other hand, the start time is configured by the search space set configuration itself, for example, at which OFDM symbol the UE begins monitoring the PDCCH of the search space for that set. Combined, the configuration of the search space set and the configuration of the CORESET provide a well-defined requirement for the UE's PDCCH monitoring in both the frequency and time domains. Both the configuration of the CORESET and the search space set can be performed semi-statically via RRC signaling.

[0134] The first CORESET, or CORESET 0, is provided by the Master System Information Block (MIB) as part of the initial bandwidth configuration to enable the reception of remaining system information and additional configuration information from the network. After the connection is established, multiple CORESETs can be configured for the UE using RRC signaling.

[0135] In NR, flexible slot formats can be configured for the UE via cell-specific and / or UE-specific higher-layer signaling in a semi-static downlink / uplink assignment manner, or via dynamic signaling in DCI format 2_0 within the group-common PDCCH (GC-PDCCH). When dynamic signaling is configured, the UE will monitor the GC-PDCCH (DCI format 2_0) carrying the Dynamic Slot Format Indicator (SFI). Other fields include available RB set indicators, COT (Channel Occupancy Time) duration indicators, and search space set monitoring group flags, as specified in TS 38.212 v16.1.0, section 7.3.1.3.1.

[0136] Conceptually, Figure 6 An illustrative description of the relationship between the bandwidth portion, CORESET, search space, and PDCCH candidates that the UE can monitor is provided. From Figure 6Obviously, each BWP shows one CORESET, although there may be more than one CORESET, including public and UE-specific CORESETs (e.g., up to 3 CORESETs per BWP). Each CORESET can then have several search spaces, each with one or more PDCCH candidates.

[0137] Search space group switching

[0138] In 3GPP, the concept of configuring at least two search space sets (abbreviated as SSS or SS set) for monitoring PDCCH has been discussed. This concept may be particularly useful for operations, for example, in unlicensed radio spectrum, where a gNB must first acquire the channel before being allowed to transmit PDCCH.

[0139] For example, different SSS groups can differ based on when and / or for how long the UE is required to monitor the PDCCH during a time slot. This is in Figure 7 The following is illustrated exemplarily. It is thus apparent that two distinct search space sets are configured, where group OFS set configuration requires PDCCH monitoring at, for example, the granularity of every second time slot (here, the first OFDM symbol of each time slot), and group 1SS set configuration requires PDCCH monitoring at the time slot granularity (here, for example, the first two OFDM symbols of each time slot). According to an exemplary 3GPP solution, the gNB can configure the search space to be monitored by the UE using the information element search space (e.g., see, TS 38.331 v16.0.0, section 6.3.2), including the monitoring slot periodicity using the parameter monitoring slot periodicity and offset. The number of OFDM symbols monitored within a time slot can be configured by the gNB using the parameter monitoring symbols within a slot, which can also be carried in the information element search space.

[0140] For example, the UE is required to monitor at least the search space of the currently active SSS group. In addition, there may be search space sets that do not belong to the configured groups (e.g., common search space sets), which the UE will always monitor regardless of the active SSS group.

[0141] Various groups can include various sets of search spaces. A single search space set can be part of more than one SSS group.

[0142] According to one exemplary aspect of this concept, the UE can be configured to hand over between groups. A specific exemplary implementation of search space set handover is defined in Section 10.4, “Search Space Set Handover,” of TS 38.213 v16.1.0, a 3GPP specification for 5G NR, in particular. Figure 8A and 8B The document provides a simplified and exemplary description of this switching.

[0143] It is thus evident that handover between search space sets can be controlled explicitly and implicitly. Based on the gNB configuration (e.g., using a specific search space set handover trigger (SearchSpaceSwitchTrigger-r16) as part of the information element slotFormatIndicator (see Section 6.3.2 of TS 38.331 v16.0.0), the UE is configured to follow either implicit or explicit handover schemes. For example, in the following example, it is assumed that there are two, SSS group 0 and SSS group 1.

[0144] Explicitly instruct working based on the switching field value carried in the DCI of format 2_0 (see Figure 8A If the switching field value is 0, the UE is instructed to monitor the PDCCH according to the search space set with the indicated group index 0. Accordingly, if this is not already done, the UE begins monitoring the PDCCH timing for SSS group 0 and stops monitoring the PDCCH timing for SSS group 1.

[0145] As described in the previous section, DCI format 2_0 can currently be used to notify UEs of group slot format, COT duration, available RB set, and search space group switching.

[0146] Conversely, if the handover field value is 1, the UE is instructed to monitor the PDCCH according to the search space set with the indicated group index 1. Accordingly, if this is not already done, the UE begins monitoring the PDCCH timing for SSS group 1 and stops monitoring the PDCCH timing for SSS group 0. Furthermore, the UE can set an appropriate timer to a configured timer value. When the timer expires, it is then used to switch back to PDCCH monitoring according to SSS group 0. Alternatively, the UE can also switch back to PDCCH monitoring according to SSS group 0 after the channel occupancy duration used for its serving cell.

[0147] Implicit SSS group switching is based on DCI monitoring on the PDCCH. From Figure 8BObviously, if the UE detects any DCI on SSS group 0, the UE starts monitoring according to SSS group 1 and stops monitoring according to SSS group 0. Furthermore, the UE starts a timer, and upon expiration, switches back to monitoring according to SSS group 0. Otherwise, the UE continues to perform PDCCH monitoring according to SSS group 1.

[0148] Time-domain scheduling in 5G NR

[0149] In the time domain, transmissions in 5G NR are organized into 10ms long frames, each divided into 10 equally sized 1ms long subframes. Subframes are further divided into several time slots, each containing 14 OFDM symbols. The duration of a time slot is in milliseconds and depends on the parameter set. For example, for a subcarrier spacing of 15kHz, NR time slots therefore have the same structure as LTE subframes with a regular cyclic prefix. Subframes in NR serve as time references independent of parameter sets, which is useful, especially when multiple parameter sets are mixed on the same carrier; however, time slots are typically dynamic scheduling units. This frame structure, upon which 3GPP 5G NR communicates, is... Figure 9 As exemplarily shown in the figure.

[0150] 3GPP NR also supports more efficient low-latency transmission methods by allowing shorter time slot sizes, known as mini-slots. Figure 9 As shown in the diagram. Mini-slot-based (also known as non-slot-based) transmissions can also preempt slot-based transmissions already in progress to another device, allowing for instantaneous transmission of application data requiring very low latency. Mini-slots can be used for low-latency applications, such as operation in URLLC and unlicensed bands, for example, to begin transmission directly after a successful listen-before-talk procedure without waiting for slot boundaries. More generally, mini-slots can be configured to span between 1 and 13 OFDM symbols. For ease of illustration, Figure 9 The mini-slots shown in the diagram exemplify spanning two, four, or seven OFDM symbols. For example, the first symbol of a mini-slot includes (uplink-dependent or downlink-dependent) control information.

[0151] The following section presents an exemplary implementation of time-domain resource allocation based on current 3GPP technical specifications. The explanations herein should be understood as specific exemplary implementations of time-domain resource allocation, and not as the only possible time-domain resource allocation.

[0152] The time-domain allocation of data to be received or transmitted is dynamically signaled in the DCI. This is useful because, as a result of the use of resources for dynamic TDD or uplink control signaling, the portion of time slots available for downlink reception or uplink transmission can vary from time slot to time slot. The time slot in which the transmission occurs is signaled as part of the time-domain allocation. Although downlink data is often transmitted in the same time slot as the corresponding resource assignment, this is not always the case, for example, when used for uplink transmission.

[0153] When a UE is scheduled to receive PDSCH or transmit PUSCH via DCI, the Time Domain Resource Assignment (TDRA) field value of the DCI indicates the row index of the Time Domain Resource Assignment (TDRA) table available to the UE and gNB. The term "table" is used herein because TDRA entries are presented as tables in the relevant 3GPP technical specifications, but should be interpreted as a logical and fairly non-limiting term. Specifically, this disclosure is not limited to any particular organization, and the TDRA table can be implemented in any manner as a set of parameters associated with separate entry indexes.

[0154] For example, rows in the TDRA table indexed by the DCI define several parameters that can be used for radio resource allocation in the time domain. In this example, the TDRA table may indicate the slot offset K0 / K2, the start and length indicator SLIV, or directly indicate the start symbol S and the allocation length L. Furthermore, the TDRA table may also indicate the PDSCH mapping type assumed in PDSCH reception and dmrs-TypeA-Position, parameters that are not directly related to the scheduled time-domain radio resources. The time-domain allocation field in the DCI is used as an index to this table, from which the actual time-domain allocation is obtained. In such an exemplary implementation, the DCI indication (a value of the row index) of a row in the TDRA table therefore corresponds to an indication of a specific combination of values ​​for dmrs-TypeA-Position, PDSCH mapping type, K0 value, S value, and / or L value.

[0155] There is at least one table for uplink scheduling authorization and one table for downlink scheduling assignment. For example, 16 rows can be configured, where each row contains:

[0156] • Slot offset (K0, K2) is the offset relative to the slot in which the DCI is obtained. Currently, downlink slot offsets from 0 to 3 are possible, however, uplink slot offsets from 0 to 7 can be used. The slot offset can also be referred to as the gap (e.g., time slot or slot interval) between the slots of the PDCCH (including K0 / K2) and the corresponding PDSCH slots scheduled by the PDCCH, as the number of slots.

[0157] • The first OFDM symbol in the time slot where the data is transmitted.

[0158] • The transmission duration of the number of OFDM symbols in a time slot. Not all start and length combinations are suitable for transmission within a single time slot. Therefore, the start and length are jointly encoded to cover only the valid combinations.

[0159] For downlink, the PDSCH mapping type, i.e., the DMRS location, is also part of this table. This provides more flexibility compared to indicating the mapping type separately.

[0160] For example, the DL slot offset of one slot will be indicated in the DCI of slot n, and therefore the scheduled PDSCH will be transmitted in slot n+1. The start symbol can be the 4th symbol of slot n+1, and the duration of the scheduled PDSCH can be 4 symbols.

[0161] The current 3GPP standard TS 38.214 v16.1.0, such as Section 5.1.2 for DL ​​and Section 6.1.2 for UL, relates to time-domain scheduling and provides several default tables that can be used for the above aspects, for example, when no RRC-configured table (e.g., pdsch-ConfigCommon or pdsch-TimeDomainAllocationList in pdsch-Config) is available at the UE.

[0162] Multi-TTI Scheduling

[0163] In 3GPP 5G NR Release 16, it supports a single DCI scheduling multiple repeating PDSCHs or PUSCHs over multiple Transport Time Intervals (TTIs). In the following text, a TTI can be considered a time slot or a mini-time slot (see, for example...). Figure 9 (and the related descriptions above). Furthermore, for example, the transmission of a transport block within a TTI is referred to hereinafter as a (single) transmission; conversely, the reception of a transport block within a TTI is referred to hereinafter as a (single) reception.

[0164] Exemplary multi-TTI scheduling in Figure 10 As shown, according to this multi-TTI scheduling, a DCI in time slot n schedules the first PDSCH in time slot n+1 and the second PDSCH in time slot n+2. Exemplarily, both PDSCHs begin with the third symbol in the time slot and have a length of 12 OFDM symbols. The transmission is therefore repeated once in time slot n+2, which is consecutive to the first transmission at time slot n+1.

[0165] The above Figure 10The multi-TTI scheduling example is just one instance; other possibilities exist. For instance, repeated transmissions could begin at the same time slot n where the DCI is received.

[0166] In the aforementioned connection, a specific TDRA table can be configured for the gNB with additional repetition parameters. In the uplink, for example, the PUSCH-TimeDomainResourceAllocationListNew information element can be configured by the gNB to define the time-domain relationship between the PDCCH (DCI) and the PUSCH in DCI formats 0_1 / 0_2. This information element can contain the number of repetitions -r16, which can be {n1,n2,n4,n7,n12,n16} (see Section 6.3.2 of TS 38.331 v16.0.0). For example, n1 can be interpreted as meaning only one transmission was performed, effectively disabling the repetition mechanism; n2 can be interpreted as meaning a total of two TB transmissions were performed; and so on.

[0167] On the other hand, for the downlink, for example, the information element PDSCH - Time Domain Resource Allocation List can be used by the gNB to configure a specific TDRA table for the time domain relationship between the PDCCH and PDSCH. This information element can contain an optional parameter, repetitionNumber, which can take values ​​from {n2, n3, n4, n5, n6, n7, n8, n16} (see Section 6.3.2 of TS 38.331 v16.0.0). For example, n2 can be interpreted as meaning that a total of two TB transmissions were performed; n3 means that a total of three TB transmissions were performed, and so on.

[0168] Currently, 5G NR implementations assume continuous transmission, i.e., repetition over consecutive TTIs. However, in future versions of telecommunications standards, such as 5G NR or later, this may change, potentially allowing transmission gaps to occur between each or some of the transmissions. The solution presented in this paper also applies to repetitive transmissions with transmission gaps.

[0169] Furthermore, according to the current 5G NR Release 16 definition, the repetition mechanism repeats the same information data (e.g., transport blocks (TBs) from the MAC layer) across multiple TTIs (e.g., time slots). However, this may change in future versions of the telecommunications standard, such as 5G NR or later, potentially allowing more than one transport block per DCI across multiple TTIs (in the uplink or downlink). Additionally, each transport block can be repeated sequentially (e.g., 4 total transmissions, with each transport block transmitted a total of 2 times). The solution presented in this paper is also applied to the allocation of several transport blocks per DCI.

[0170] Therefore, the concept of repetition, which has already been introduced into 5G NR Release 16, is expanded for this application. For example, in the following text, it is exemplarily assumed that a single DCI transmitted by the gNB can be allocated to multiple (i.e., more than one) transmit / receive operations, which is referred to below as multi-TTI scheduling. Thus, the multi-TTI scheduling mechanism will cover one or more TBs of transmit or receive operations, in consecutive or discontinuous TTIs, with or without an offset starting after the received DCI.

[0171] Further improvements

[0172] The inventors have identified the problems related to the above.

[0173] Specifically, the timing of PDCCH monitoring in the time domain is semi-statically configured by RRC within the search space set configuration. This is done independently and is independent of possible multi-TTI scheduling.

[0174] Therefore, even if the DCI schedules a multi-TTI transmission or reception, the semi-statically configured PDCCH monitoring timings will not be canceled, although it can be assumed that the gNB does not transmit (another) PDCCH (DCI) at these timings. Thus, the UE also performs PDCCH monitoring at PDCCH monitoring timings where further PDCCH DCIs are highly unlikely.

[0175] Such an exemplary solution is Figure 11 As shown, it assumes two subsequent single TTI allocations, followed by a multi-TTI allocation at slot n+2, which allocates three transport blocks, specifically at n+2, n+3, and n+4. Nevertheless, the UE monitors the PDCCH timing of the monitoring configuration at slots n+3 and n+4 (horizontal dashed lines) during the first three OFDM symbols of each slot.

[0176] Therefore, the UE will unnecessarily consume power by performing the monitoring function during those PDCCH monitoring times in time slots n+3 and n+4.

[0177] Therefore, the inventors have identified the possibility of providing a PDCCH monitoring function that can avoid or mitigate the problems identified above.

[0178] Example

[0179] The following describes new radio access technologies envisioned for 5G mobile communication systems, including UEs, base stations, and procedures that meet these requirements; however, these technologies can also be used in LTE mobile communication systems. Different implementations and variations will also be explained. The following disclosure is facilitated by the foregoing discussion and findings and may, for example, be based on at least a portion thereof.

[0180] Generally, it should be noted that many assumptions have been made herein to explain the basic principles of this disclosure in a clear and understandable manner. However, these assumptions should be understood as examples made herein for illustrative purposes only and should not limit the scope of this disclosure. Those skilled in the art will recognize that the principles disclosed below and the content set forth in the claims can be applied to different scenarios and in ways not explicitly described herein.

[0181] Furthermore, some terms used below, such as procedures, entities, and layers, are closely related to those used in LTE / LTE-A systems or current 3GPP 5G standards, although the specific terminology used in the context of new radio access technologies for next-generation 3GPP 5G communication systems is not fully determined or may ultimately change. Therefore, the terminology may be changed in the future without affecting the functionality of this embodiment. Accordingly, those skilled in the art will understand that this embodiment and its scope of protection should not be limited to the specific terms used exemplarily herein due to the lack of updated or finally agreed terminology, but should be understood more broadly based on the functions and concepts that form the functional and principle basis of this disclosure.

[0182] For example, a mobile station, mobile node, user terminal, or user equipment (UE) is a physical entity (physical node) within a communication network. A node can have several functional entities. A functional entity refers to a software or hardware module that implements and / or provides a predetermined set of functions to the same node, another node, or other functional entities in the network. A node can have one or more interfaces that connect the node to communication facilities or media through which the node can communicate. Similarly, a network entity can have logical interfaces that attach functional entities to communication facilities or media, through which it can communicate with other functional entities or corresponding nodes.

[0183] Here, "base station" or "radio base station" refers to a physical entity within a communication network. Like a mobile station, a base station can have several functional entities. A functional entity is a software or hardware module that implements and / or provides a predetermined set of functions to other functional entities on the same node, another node, or within the network. Physical entities perform control tasks related to the communication equipment, including one or more of scheduling and configuration. It's important to note that base station functionality and communication equipment functionality can also be integrated into a single device. For example, a mobile terminal can also implement base station functionality for other terminals. The term used in LTE is eNB (or eNodeB), while the term currently used in 5G NR is gNB.

[0184] Communication between the UE and the base station is usually standardized and can be defined by different layers, such as PHY, MAC, RRC, etc. (see the background discussion above).

[0185] The terms "send or receive" and "send / receive" as used in this document should be understood as applying the concept to the scheduling DCI, regardless of whether the scheduling DCI schedules scheduled send or receive. Similarly, when referring to the number of send or receive operations, it should be understood as the specific number of send or receive operations allocated to the UE by the scheduling DCI.

[0186] The term “single TTI scheduling” (and similar terms) used in this document should be understood as scheduling a DCI that schedules a single transmission or reception of data, for example, occurring within a single TTI.

[0187] On the other hand, the term "multiple TTIs" as used in this paper should be understood as referring to a DCI that schedules multiple transmissions or receptions of data, for example, occurring over several TTIs. Multiple transmissions or receptions can convey the same data at different transmission / reception times (i.e., TTIs), i.e., in the sense of data duplication. Alternatively, multiple transmissions or receptions can transmit different data separately at different transmission / reception times (i.e., TTIs), thereby increasing data throughput. Furthermore, alternatively, multiple transmissions or receptions can convey the same data at some different transmission / reception times and different data at other different transmission / reception times.

[0188] The term "search space set" can be broadly understood as a collection of search spaces, with multiple search spaces, each including one or more possible candidates for receiving DCI messages. For example, a search space might include various candidate groups with the same aggregation level but different DCI message formats. Furthermore, a search space set could include search spaces with different aggregation levels but associated with the same set of time-frequency resources to be monitored (e.g., the same CORESET). As explained above, the 3GPP 5G NR standard provides a specific exemplary implementation. The terms "search space set" and "group of search space sets" are used herein to name the basic concepts but should not be considered limiting.

[0189] The term "monitoring" can be broadly understood as attempting to decode potential candidates for receiving DCI messages, for example, based on a specific format. Such decoding attempts can also be called blind decoding.

[0190] Figure 12 A general, simplified, and exemplary block diagram is shown for a user equipment (also known as a communication device) and a scheduling device (here, it is exemplarily assumed to be located in a base station, such as an eLTE eNB (alternately referred to as an ng-eNB) or a gNB in ​​5G NR). The UE and the eNB / gNB communicate with each other over a (wireless) physical channel using transceivers, respectively.

[0191] Communication equipment may include transceivers and processing circuitry. A transceiver may sequentially include a receiver and a transmitter, and / or function as both a receiver and a transmitter. The processing circuitry may be one or more pieces of hardware, such as one or more processors or any LSI. Input / output points (or nodes) exist between the transceiver and the processing circuitry, through which the transceiver can be controlled, i.e., the receiver and / or transmitter can be controlled, and received / transmitted data can be exchanged. The transceiver, acting as both a transmitter and receiver, may include an RF (radio frequency) front-end containing one or more antennas, amplifiers, RF modulators / demodulators, etc. The processing circuitry may perform control tasks, such as controlling the transceiver to transmit user data and control data provided by the processing circuitry and / or to receive user data and control data, which are further processed by the processing circuitry. The processing circuitry may also be responsible for performing other processing, such as determination, decision-making, calculation, measurement, etc. The transmitter may be responsible for performing transmission processing and other related processing. The receiver may be responsible for performing reception processing and other related processing, such as monitoring the channel.

[0192] An improved downlink control channel (e.g., PDCCH) monitoring procedure will be described below. In this connection, an improved UE and an improved base station are presented, participating in the improved downlink control channel monitoring procedure (also exemplarily referred to below as the PDCCH monitoring procedure). Corresponding methods for UE behavior and base station behavior are also provided.

[0193] Figure 13 A simplified and exemplary UE structure is shown as an exemplary solution based on an improved PDCCH monitoring program, and it can be based on... Figure 12 The relevant explanation is based on a general UE architecture. The various structural elements of the UE shown in the figure can be interconnected, for example, with corresponding input / output nodes (not shown), for example, to exchange control and user data and other signals. Although not shown for illustrative purposes, the UE may include further structural elements.

[0194] from Figure 13 Obviously, the UE may include processing circuitry for downlink control channel monitoring, processing circuitry for determining search space sets, and a receiver for receiving downlink control information messages.

[0195] In the present case, as will become apparent from the following disclosure, the receiver of the UE can therefore be configured, by way of example, to perform at least in part one or more of receiving downlink control information messages, receiving allocated data, and receiving configuration information.

[0196] Furthermore, in the present case, as will become apparent from the following disclosure, the UE’s processing circuitry (also referred to as the processor) can therefore be exemplarily configured to perform at least in part one of the following: performing monitoring functions for the downlink control channel, determining search space groups, determining the content of downlink control information messages, determining the number of transmissions or receptions assigned by the content of the downlink control information messages, determining the identifier of the search space groups, and determining the priority of the data to be transmitted or received assigned by the content of the downlink control information messages.

[0197] Furthermore, in the present case, as will become apparent from the following disclosure, the UE’s transmitter can therefore be configured, by way of example, to perform at least partially the transmission of one or more of the allocated data, etc.

[0198] The exemplary solution, further detailed below, is implemented by a UE comprising the following: The UE's processor runs a monitoring function involving monitoring a downlink control channel used for receiving downlink control information messages based on one of multiple search space sets. The UE's receiver receives downlink control information messages via the monitored downlink control channel, wherein the received downlink control information messages assign data transmission or reception to the UE. The processor also determines one of the multiple search space sets used to perform the downlink control channel monitoring function. The determination of this search space set is based on:

[0199] • The content or format of the received downlink control information messages.

[0200] The corresponding sequence diagram of exemplary UE behaviors conforming to the above discussion is in Figure 14 As shown in the diagram, the UE operates a monitoring function involving monitoring a downlink control channel used for receiving downlink control information messages based on one of multiple search space sets. The UE receives downlink control information messages via the monitored downlink control channel, wherein the received downlink control information messages assign data transmission or reception to the UE. The UE determines one of the multiple search space sets used to perform the downlink control channel monitoring function, wherein the determination of this search space set is based on:

[0201] • The content or format of the received downlink control information messages.

[0202] According to this improved PDCCH monitoring procedure, the UE can adapt the PDCCH monitoring function based on the allocation performed by the downlink control information (DCI) messages, by appropriately determining different, more suitable search space sets (SSS) to perform the monitoring function. For example, the periodicity of the required monitoring timing of the downlink control channel of the new SSS group may change depending on how the base station schedules the UE in the received DCI messages. In short, the monitoring requirements imposed on the UE can be matched with the base station's scheduling intentions or needs.

[0203] As is evident from the above, the improved downlink control channel monitoring procedure also provides improved radio base stations. Figure 15 A simplified and exemplary base station structure is shown, illustrating an exemplary solution based on an improved downlink control channel monitoring procedure, and it can be based on... Figure 12 The relevant explanation is implemented based on the general base station structure. In the... Figure 15 The various structural elements of the radio base station shown can be interconnected, for example, with corresponding input / output nodes (not shown), for example, to exchange control and user data and other signals. Although not shown for illustrative purposes, the base station may include further structural elements.

[0204] from Figure 15 Obviously, the base station may include processing circuitry for generating downlink control information messages, processing circuitry for determining search space sets, and a transmitter for sending downlink control information messages.

[0205] In the present case, as will become apparent from the following disclosure, the base station’s processing circuitry can therefore be exemplarily configured to perform at least in part the following functions: generating downlink control information messages (including setting the content and format of the messages and determining the search space set), determining the number of transmissions or receptions allocated by the BS in previously transmitted downlink control information messages, running one or more timers (such as a disable timer and a handover timer), etc.

[0206] In the present case, as will become apparent from the following disclosure, the base station transmitter can therefore be configured, by way of example, to perform at least in part one or more of sending downlink control information messages and sending configuration messages to the UE.

[0207] In the present case, as will become apparent from the following disclosure, the base station’s receiver can therefore be configured, by way of example, to perform at least in part one or more of the transmission of receiving data from the UE.

[0208] An exemplary solution, further detailed below, is implemented by a radio base station comprising the following: The BS's processor generates downlink control information messages, which assign data transmission or reception to the UE. Furthermore, the content or format of the generated downlink control information message enables the UE to determine one of multiple search space sets. This determined search space set is used by the UE to perform a surveillance function involving monitoring the downlink control channel used for receiving downlink control information messages. The BS processor determines the set of multiple search space sets currently used by the UE for performing the surveillance function. The determination of the currently used search space set is based on the content or format of another downlink control information message previously sent to the UE. The BS transmitter, based on the determined currently used search space set, sends the generated downlink control information message to the UE via the downlink control channel.

[0209] The corresponding sequence diagram of exemplary base station behavior conforming to the above base station is in Figure 16As shown in the diagram. Based on this improved base station behavior, the base station generates a downlink control information message (Downlink Control Information Message), which assigns data transmission or reception to the UE. The content or format of the generated Downlink Control Information Message enables the UE to determine one of multiple search space sets to be used by the UE to perform surveillance functions involving monitoring the downlink control channel used to receive Downlink Control Information Messages. The base station determines the search space set currently being used by the UE to perform surveillance functions. The determination of the currently used search space set is based on the content or format of another Downlink Control Information Message previously sent to the UE. Then, based on the determined currently used search space set, the base station sends the generated Downlink Control Information Message to the UE via the downlink control channel.

[0210] Accordingly, based on the scheduling DCI sent from the BS to the UE, the improved base station can exert some control over how the UE performs the PDCCH monitoring procedure. The scheduling DCI not only provides the UE with radio resources to allocate for downlink data reception or uplink data transmission, but is also used to control which SSS group the UE uses to perform downlink control channel monitoring functions.

[0211] In the improved downlink control channel monitoring procedure Figure 17 An illustrative example is shown, illustrating how, for a time slot sequence, the UE (and base station) depends on the receive handover search space set (SSS) group that schedules the DCI. Assume the UE begins monitoring based on SSSG 0, ​​and that it provides periodic monitoring opportunities only every fourth time slot (in n, n+4, n+8, n+12, etc.; considered sparse SSSGs, especially compared to SSSG 1). SSSG 1, on the other hand, can be considered to provide relatively dense required monitoring opportunities, specifically in every time slot.

[0212] It is also assumed that the base station knows the UE's monitoring timing and therefore uses that monitoring timing to schedule the UE in time slot n+8 (see...). Figure 17 The "Scheduled DCI" (as defined in the text) is used, for example, for downlink or uplink transmissions. In this particular example, the scheduled DCI causes the UE to switch to SSS group 1 and thus monitor the downlink control channel in each time slot. Accordingly, the content or format of this scheduled DCI is set by the gNB so that it causes the UE to switch to another SSS group. This allows the base station to schedule the UE more frequently, for example from... Figure 17The n+10, n+12, and n+13 time slots are self-evident. The UE maintains monitoring of the downlink control channel in each time slot until time slot n+17, where the base station provides another scheduled DCI, at which point the UE switches back to SSS group 0 (sparse monitoring opportunity) starting from time slot n+18. The first monitoring opportunity for SSS group 0 occurs after the handover, at n+20.

[0213] Therefore, by providing an SSSG with sparse surveillance requirements, the UE is allowed to skip certain time slots used for surveillance functions, so that power is not wasted in this regard (e.g., blind decoding is not required during those downlink control channel surveillance times).

[0214] According to one exemplary implementation, sparse SSSG will be used by the UE when the base station cannot or reasonably schedule the UE. For example, this might be a case where scheduling DCI to send or receive multiple TTIs spanning several time slots (see also the corresponding more detailed solution below). Another example is a scenario where the UE is scheduled for latency-tolerant traffic (e.g., low priority), where the UE's power-saving opportunities might be considered more important than the base station's scheduling flexibility (scheduling flexibility is generally more important for, for example, latency-tolerant traffic, such as high priority; see the corresponding more detailed solution below).

[0215] In general, UE monitoring requirements can be adapted to base station scheduling requirements. For example, when multi-TTI transmit / receive is scheduled, UE monitoring workload and the resulting power consumption are reduced, while traffic requirements can still be met. This can be beneficial if, for example, channel conditions are stable across multiple TTIs.

[0216] On the other hand, switching to single-TTI scheduling increases the monitoring workload of the PDCCH to allow for better scheduling flexibility. This can be beneficial if, for example, channel conditions become more dynamic and it becomes difficult for base stations to make good scheduling decisions across multiple TTIs. Specifically, base stations must consider the unpredictable traffic dynamics of high-priority UEs, making it impossible for them to reserve radio resources for multiple TTIs in advance.

[0217] The aforementioned scheduling DCI allocates data transmission / reception to the UE. For example, downlink control information messages allocate downlink radio resources for the UE to receive data. In an exemplary 5G NR implementation, the format of the downlink control information message can be 1_0, 1_1, or 1_2. On the other hand, downlink control information messages allocate uplink radio resources for the UE to transmit data. The format of the downlink control information message is 0_0, 0_1, or 0_2.

[0218] Although not shown in the above diagram as it is irrelevant, the UE continues to perform, for example, data transmission or reception according to the scheduling provided by a single scheduling DCI. For example, the UE performs a single data transmission (in the case of single-TTI uplink scheduling) or multiple data transmissions (in the case of multi-TTI uplink scheduling). Alternatively, the UE performs a single data reception (in the case of single-TTI downlink scheduling) or multiple data receptions (in the case of multi-TTI downlink scheduling).

[0219] In the above Figure 17 In the exemplary description (and in the following description and explanation), several assumptions have been made for ease of explanation and interpretation; however, these assumptions should not be construed as limiting the scope of the invention.

[0220] For example, one exemplary assumption is that the SSSG handover occurs at the slot boundary of a slot (e.g., slot n+1) adjacent to the slot (e.g., slot n) where the received scheduled DCI caused the handover. However, this is merely an example; the handover can also occur at different timings, such as at a later slot boundary (n+x), or at the earliest slot boundary after the scheduled DCI, considering the minimum time interval of x symbols (where x is a positive integer that can be configured or defined by a suitable 3GPP standard). Furthermore, the value of x can also depend on UE capabilities; for example, a high-end UE may support faster processing based on a lower n value, while a low-end UE may allow more processing time based on a larger n value.

[0221] Another illustrative assumption is that the two (or more) SSS groups differ from each other in the periodicity of the monitoring opportunities when the UE is required to monitor the downlink control channel used to receive DCI messages. For example, SSSG 0 has a long monitoring periodicity (long, compared to SSSG 1; here, long periodicity is 4 time slots), while SSSG 1 has a short periodicity (short, compared to SSSG 0; here, short periodicity is 1 time slot). In other words, a dense SSSG provides a large number of monitoring opportunities in the time domain (or per time domain unit) than a sparse SSSG provides only a small number of monitoring opportunities in the time domain (or per time domain unit).

[0222] However, alternatively, the various SSS groups may also differ in different ways, such as in the number of PDCCH candidates. For example, SSSG 0 contains fewer PDCCH candidates than SSSG 1. Therefore, by monitoring SSSG 0, ​​the UE can achieve power saving gains to some extent at the expense of scheduling flexibility.

[0223] Alternatively, the various SSSGs can also differ in their DCI formats. For example, SSSG 0 can be configured to contain only DCI formats 0-0 and 1-0 (also known as fallback formats because they are compact (smaller in size) and therefore have less scheduling flexibility), while SSSG 1 contains other DCI formats. The benefits of this configuration include reduced blind decoding work once the UE is monitoring SSSG 0, ​​and thus, UE power savings.

[0224] Furthermore, or alternatively, different PDCCH monitoring modes within a time slot can be configured separately for different SSSGs. For example, SSSG 0 can be configured to appear in the first two symbols of the time slot, while SSSG 1 can be configured to appear in the 7th and 8th symbols of the time slot. With such a configuration, SSG0 will be more advantageous for scheduling within the same time slot than SSSG1. This is because a PDSCH transmission or a PUSCH transmission cannot cross time slot boundaries. Therefore, by providing scheduling opportunities at the beginning of the time slot, such as SSSG 0, ​​the UE is allowed more time to process data if it is scheduled within the same time slot. In contrast, SSSG1 can be used for cross-time slot scheduling, for example, DCI in time slot n scheduling data in time slot n+1.

[0225] Another illustrative assumption made for ease of explanation is that the UE is configured with only two different search space sets. However, the concepts described herein also apply to UEs with more than two different SSS sets.

[0226] Another exemplary assumption is that one of the SSS groups is a default SSS group, for example, an SSS group that the UE initially uses to perform surveillance functions. For example, the initial or default SSS group can be defined to provide a high number of surveillance opportunities per instance to increase the base station's scheduling flexibility and thus potentially reduce scheduling latency. On the other hand, the initial or default SSS group can be defined to provide a smaller number of surveillance opportunities per instance to increase the likelihood that the UE will skip PDCCH surveillance slots to save power.

[0227] Another exemplary assumption is that the improved downlink control channel surveillance (HSC) function (e.g., including SSS group handover and time units in which the UE can be scheduled by the BS) is performed on a time slot basis (i.e., 14 OFDM symbols for the regular cyclic prefix; 12 OFDM symbols for the extended cyclic prefix). However, the improved function can also be performed on a mini-time slot basis, where a mini-time slot spans one or more OFDM symbols, but fewer than a full time slot (i.e., <14 OFDM symbols for the regular cyclic prefix; <12 OFDM symbols for the extended cyclic prefix). For example, the surveillance function would be performed on each mini-time slot, e.g., every two OFDM symbols. Therefore, the mini-time slots constitute the TTI in which the UE can be scheduled.

[0228] Although not explicitly mentioned, another exemplary assumption is that the UE is scheduled to receive or transmit the same data in a multi-TTI schedule. However, this is not considered a limitation of the improved procedure. Rather, the improved PDCCH monitoring procedure also applies to situations where several transport blocks can be scheduled by a single DCI. In other words, multi-TTI scheduling does not just refer to the same single transport block (and thus effectively duplicates it), but to more than one transport block (each of which may then also be duplicated in the same multi-TTI schedule).

[0229] The improved PDCCH monitoring procedure explained above also involves the base station, which is responsible for sending the scheduled DCI to the UE. For example, the base station performs steps corresponding to those on the UE side to allow it to determine how the UE monitors the PDCCH. This is advantageous for the base station because it can send the scheduled DCI at the time slot (and OFDM symbols) when the UE is actually monitoring the downlink control channel. For example, the base station can perform the same determination as the UE for determining the SSS group. The basic behavior of the base station is as follows: Figure 16 As shown in the image.

[0230] There are several possibilities regarding how a UE determines the SSSG it should use for surveillance functions based on a scheduled DCI (e.g., based on the content or format of the scheduled DCI). A brief overview of these solutions is provided, followed by a more detailed explanation of each.

[0231] The first solution distinguishes between scheduling DCI (single-TTI scheduling) that schedules a single transmit or receive operation and scheduling DCI (multi-TTI scheduling) that schedules multiple transmits or receives operations. A variant of the first solution incorporates the prohibition of time periods to ensure that handover is applied to the minimum amount of time.

[0232] The second solution provides a more explicit indication of the SSS group that the UE will use for surveillance functions, for example by including a field in the scheduling DCI that allows the UE to directly identify the SSS group. A variant of this second solution incorporates a further handover mechanism based on a handover time period to switch back to another SSS group after the handover time period expires.

[0233] The third solution is to prioritize data based on DCI scheduling.

[0234] First Solution - Implicit Indication of SSS Groups Based on Single-TTI vs. Multi-TTI Scheduling DCI

[0235] The first solution (and its variants) is presented below regarding how the UE determines the SSSG it should use for PDCCH monitoring based on the scheduling DCI. This first solution revolves around the idea of ​​distinguishing between scheduling DCIs that schedule a single transmit or receive (single-TTI scheduling) and scheduling DCIs that schedule multiple transmits or receives (multi-TTI scheduling).

[0236] According to one exemplary implementation, the scheduling DCI indicates the number of transmit or receive assignments allocated to the UE by the base station. Therefore, it allows the UE to distinguish between single-TTI scheduling and multi-TTI scheduling, and on this basis, appropriately determine the SSSG to which the UE should operate the PDCCH monitoring function.

[0237] In an exemplary 5G-NR standard-based implementation, the UE is configured with a specific TDRA table, which has parameters indicating the number of transmissions or receptions. Accordingly, the scheduling DCI identifies a set of parameters (e.g., rows) of the TDRA table, and thus also identifies whether the allocation refers to a single transmission / reception or multiple transmissions / receptions.

[0238] In one exemplary implementation, the parameters in the TDRA table can be standardized repetition parameters, as explained above ("repetitionNumber" for PDSCH; "numberOfRepetitions" for PUSCH). In this case, multi-TTI transport will refer to the repetition of the same data (e.g., the same transport block) on different TTIs.

[0239] The aforementioned TDRA table can be fixed by the 5G standard, for example, or it can be configured by the gNB.

[0240] A flowchart of UE behavior based on a simplified and exemplary implementation of the first solution is shown in Figure 18Presented. It is thus evident that only two different SSSGs are available for handover: the initial SSSG 0 with a dense PDCCH monitoring mode, and SSSG 1 with a sparse PDCCH monitoring mode. The UE therefore assumes to initially operate the monitoring function based on SSSG 0, ​​which allows the UE to eventually receive scheduled DCI messages from the base station. Consistent with the first solution, the UE determines whether the scheduled DCI message is for a single-TTI or multi-TTI transmission. If the UE is scheduled for a single-TTI transmission, it will monitor the PDCCH more frequently and thus follow the monitoring timing according to SSSG 0. On the other hand, if the UE is scheduled for a multi-TTI transmission, it is allowed to relax PDCCH monitoring, as further scheduled DCIs are unlikely and unnecessary to be sent so frequently; the UE thus follows the monitoring timing according to the other SSS group 1.

[0241] Although not mentioned above, when the UE switches to another SSSG for performing surveillance functions, this implicitly involves the UE ceasing to follow the surveillance timing according to the previous SSSG.

[0242] The UE can then repeat the process discussed above in order to keep its PDCCH monitoring adapted to the schedule (e.g., the received schedule DCI).

[0243] The resulting switching between the two SSS groups used to perform PDCCH monitoring functions Figure 19 and 20 As shown. Figure 19 It is a detailed time slot diagram showing the PDCCH monitoring timing for both SSS group 0 and SSS group 1. SSS group 0 requires PDCCH monitoring every second time slot for one OFDM symbol, while SSS group 1 requires PDCCH monitoring for every time slot for two OFDM symbols. Figure 19 The third line shows the actual scheduling and monitoring performed by the UE, which depends on the scheduling DCI received by the UE, as shown above. Figure 18 The relevant discussion.

[0244] In this particular exemplary scenario, it is assumed that the UE is already running its surveillance function and, in time slot n, is monitoring the PDCCH according to SSSG 1 (see...). Figure 19The third time slot (n) refers to the period between the first two OFDM symbols. The UE receives a scheduled DCI from the base station in time slot n, which schedules multiple transmissions / receptions of the same or different data. Therefore, the UE determines to switch to SSSG 0 to allow skipping PDCCH monitoring every second time slot. In this case, the UE switches to the SSSG 0 configuration at the time slot boundary between time slots n and n+1, where time slot n+1 does not have a monitoring timing according to the SSSG 0 configuration.

[0245] The base station uses the PDCCH monitoring timing at time slot n+4, which the UE follows, to provide the UE with a single-TTI scheduling DCI. The UE then switches to SSSG 1 and begins monitoring the PDCCH in time slot n+5 according to the PDCCH monitoring timing defined by SSSG 1. This increases scheduling flexibility because a scheduling opportunity for the base station is available in every time slot. Another single-TTI is scheduled by the scheduling DCI in time slot n+5, and the UE continues to perform monitoring according to SSSG 1 until time slot n+7. In time slot n+7, the UE receives a multi-TTI scheduling DCI that causes the UE to switch back to SSSG 0 at the next time slot boundary, n+8.

[0246] Figure 20 Is with Figure 19 Compared to another similar but simplified time-slot diagram, let's again assume two distinct SSS groups are defined: SSSG has sparse monitoring opportunities every four time slots (n, n+4, n+8, etc.), while SSSG 1 has relatively dense monitoring opportunities occurring in every time slot. It is thus evident that the handover is triggered by reception scheduled by a single-TTI or multi-TTI. In this case, a single-TTI scheduled DCI transmitted by the base station in time slot n+8 causes the UE to switch to the dense SSSG 1 from time slot n+9. The base station uses better scheduling flexibility to schedule further single-TTI transmissions / receptions in time slots n+9, n+11, and n+12. When a multi-TTI scheduled DCI is received in time slot n+17, the UE switches back to monitoring the PDCCH based on SSSG 0 from the next time slot n+18. According to SSSG 0, ​​the next monitoring opportunity is in time slot n+20, thus allowing the UE to skip monitoring PDCCH in time slots n+18 and n+19 (and also in n+21 and n+22).

[0247] In the exemplary implementation of the first solution described above, it is conjectured that the UE is configured with only two different SSSGs for performing the improved PDCCH monitoring procedure. In the case of more than two SSSGs, the UE needs to further select among the various SSSGs in some way. This can be done, for example, by comparing the number of scheduled transmissions for the DCI with the periodicity of the required monitoring timing for the different SSSGs, and then selecting the SSSG with the periodicity of the required monitoring timing that best matches the number of scheduled transmits / receives.

[0248] For example, we can assume a scenario with three SSS groups, where SSSG 0 has a monitoring periodicity of 4 time slots (see...). Figure 20 SSSG 0), SSSG 1 has a 2-slot monitoring periodicity (see SSSG 0). Figure 19 SSSG 0), and SSSG 2, which has a monitoring periodicity of one time slot (see, for example, SSSG 0). Figure 19 Or SSSG 1 of 20). When the scheduling DCI allocates four time slots (n to n+3) (or more than four time slots) for multi-TTI transmission in time slot n, the UE can determine SSSG 0, ​​which has a monitoring period of 4 time slots. When the scheduling DCI schedules three time slots for multi-TTI transmission, the UE can determine SSSG 1 with a monitoring period of 2 time slots (thus providing increased scheduling flexibility at the cost of reduced power saving potential) or SSSG 0 with a monitoring period of 4 time slots (thus providing reduced scheduling flexibility but benefiting from increased power saving potential). When the scheduling DCI allocates two time slots (n and n+1) for multi-TTI transmission in time slot n, the UE can determine SSSG 1, which has a monitoring period of 2 time slots.

[0249] A variant of the first solution incorporates a prohibited time period that ensures the UE applies the minimum amount of time required to change the SSSG before a possible switch to another SSSG (or a previous SSSG). In other words, during this prohibited time period after a switch to a different SSSG, the UE will not perform another change to the SSSG, even if receiving a scheduling DCI from the UE would make such a change possible. Therefore, the UE is prohibited from determining a search space group different from the currently used SSSG within a time period (after the currently used SSSG has been determined).

[0250] The prohibited time period can apply to only one or some of all SSSGs, or it can apply to all SSSGs. For example, applying the prohibited time period when an SSSG has been changed to one with sparse monitoring timing can ensure more power savings because the UE follows the sparse monitoring timing for a minimum amount of time. Conversely, applying the prohibited time period when an SSSG has been changed to one with dense monitoring timing can ensure more scheduling flexibility.

[0251] In one exemplary implementation, the prohibition period can be implemented based on a prohibition timer run by the UE. This is in Figure 21 The behavior of the UE is illustrated by way of example in the flowchart. Figure 21 Similar in the following aspects Figure 18 That is, the UE determines which SSS group to use based on whether the received scheduling DCI allocates single-TTI or multi-TTI transmission / reception. Besides Figure 18 In addition to the steps, Figure 21 Steps related to disabling timer operation in both branches (i.e., multi-TTI and single-TTI branches) have been incorporated.

[0252] Specifically, it is exemplarily assumed that the disable timer is applied only when switching back from sparse SSSG 1 to dense SSSG 0 (but not the other way around). Accordingly, when switching to SSSG 1, which is related to multiple TTIs, the disable timer is started and runs for a specific time period (e.g., the disable time period described above). Figure 21 As is evident, when a UE is scheduled for single-TTI transmission / reception, the UE additionally determines whether a disable timer is running (expiring). When the disable timer is not running, the UE can switch to SSSG 0 associated with the single-TTI, or if it is running, wait for the disable timer to expire.

[0253] In one optional implementation scheme (in) Figure 21 (Shown as dashed lines) The disable timer is restarted when it has already run and when the UE determines the multi-TTI scheduling DCI again. Therefore, the disable period is extended each time a multi-TTI scheduling DCI is received.

[0254] Figure 22 This is a state diagram of an exemplary implementation of the first timer-based solution described above, and it illustrates the relationship with... Figure 21 A solution similar to the one described above. Figure 22In the state diagram, it is assumed that the UE starts PDCCH monitoring based on SSSG 0, ​​which has a dense monitoring timing, making higher scheduling flexibility possible by default. Accordingly, the UE switches from SSSG 0 to SSSG 1 based on multi-TTI scheduling DCI, but continues to use SSSG 0 when a single-TTI scheduling DCI is detected. Also... Figure 21 The assumption made in Figure 22 In one exemplary implementation, the timer is disabled only when switching from SSSG 1 to SSSG 0, ​​thus preventing the UE from switching back to SSSG 0 even when it receives a single-TTI scheduling DCI.

[0255] In addition, there is another possibility: after the UE has received a single-TTI scheduling DCI and is waiting for the disable timer to expire, the handover to SSSG 0 that has already been initiated is aborted, i.e., when a multi-TTI scheduling DCI is received again. In this case, the disable timer avoids the ping-pong effect (handover back and forth).

[0256] Figure 23 This is another state diagram based on another exemplary implementation of the first timer-based solution described above. It is mainly related to... Figure 22 The state diagrams differ in that SSSG 0 uses a sparse surveillance scheme, while SSSG 1 uses a dense surveillance scheme. This allows the UE to initiate PDCCH surveillance based on the sparse surveillance scheme, which by default allows for greater power savings at the UE. Conversely, the handover from SSSG 0 to SSSG 1 is based on detection-only single-TTI scheduling of DCI, and vice versa. Furthermore, timers are disabled for the handover from dense to sparse surveillance, ensuring a minimum time commitment for better scheduling flexibility.

[0257] The first solution described above (and its variations) can also be implemented at the base station. As generally mentioned above, the base station performs steps corresponding to those on the UE side to allow the base station to determine how the UE monitors the PDCCH and then perform actions accordingly (e.g., send the next scheduled DCI). In this first solution, the base station thus determines the SSS group currently used at the UE based on the number of transmit / receive operations assigned to the UE by the content of the previously sent scheduled DCI. Additionally, for the solution based on prohibited time periods described above, the base station also considers such prohibited time periods to correctly determine UE behavior and thus determine the SSS group currently used by the UE for PDCCH monitoring.

[0258] Accordingly, the base station synchronizes with the UE regarding which SSS group the UE is currently using, and therefore which monitoring time the UE can use to send a scheduled DCI that the UE can receive.

[0259] Second Solution - Explicit Instructions from the SSS Group

[0260] The second solution (and its variants) will be presented below, regarding how the UE determines the SSSG that should be used for the PDCCH monitoring function based on the scheduling DCI.

[0261] According to this second solution, the explicit indication of the SSS group used by the UE for monitoring functions is provided by the scheduling DCI, for example, by including a field in the scheduling DCI that allows the UE to directly identify the SSS group. Accordingly, the UE determines the identifier of the SSS group to be used by the UE for PDCCH monitoring based on the field as part of the scheduling DCI content.

[0262] By using explicit indication of SSS groups, the base station has more flexibility to control which SSS groups the UE should monitor.

[0263] An exemplary implementation of the second solution is in Figure 24 The diagram illustrates the UE's behavior. It is evident that after receiving the scheduling DCI message, the UE determines the identifier of the SSS group from the fields of the scheduling DCI message. The UE then continues to perform monitoring functions based on the identified SSSG.

[0264] The following section will discuss two alternative variants of the second solution.

[0265] According to a first variant of the second solution, the scheduling DCI includes a field that includes a value identifying the SSS group to be used. This field may, for example, be called the Search Space Set Group field (SSSG field) and will be a separate field in the DCI. For example, in the case of only two SSS groups, the SSSG field only needs to have one bit to distinguish between the two SSSGs; a bit value of 0 to identify SSSG 0 and a bit value of 1 to identify SSSG 1. On the other hand, the SSSG field can have more than one bit to distinguish between more than two SSS groups.

[0266] According to a second variant of the second solution (which may supplement or replace the first variant), the SSSG identifier is jointly encoded into a resource allocation field, which, for example, indicates time-domain scheduling parameters related to the allocated transmit / receive. In other words, the resource allocation field of the scheduling DCI allows the UE to determine both the time-domain scheduling parameters and the identifier of the SSS group the UE will use. The advantage of the second variant compared to the first variant is that the scheduling DCI does not have a separate field for the SSSG identifier, thus reducing overhead.

[0267] According to one exemplary implementation, time-domain scheduling can be based on a suitable Time-Domain Resource Allocation (TDRA) table (e.g., a table provided by the 5G NR standard). Accordingly, the various time-domain scheduling parameter sets in the TDRA table can also indicate the SSSG identifier. Therefore, when the resource allocation field of the scheduling DCI indicates which parameter set in the TDRA table is used, that resource allocation field also identifies the SSSG that the UE must use for surveillance functions.

[0268] The following exemplary TDRA table can be fixed in a suitable 5G NR standard, or it can be configurable by the gNB (e.g., using RRC).

[0269] TDRA table

[0270]

[0271] As is evident from the exemplary table, each set of time-domain scheduling parameters is placed in a row of the table and associated with a row index, as indicated by the scheduling DCI. In this particular example, the repetition of transmissions (this is just an example; it could also be multi-TTI scheduling of different TBs) can be guided by the base station, with the time-domain scheduling parameter sets indexed by row index values ​​2, 3, and 4. Furthermore, a corresponding SSSG index is provided for each row.

[0272] It is evident from the TDRA table above that the SSSG index associated with row index 2 (and therefore with a repetition count of n2; multi-TTI transmission) is also SSSG 0 (e.g., assuming a monitoring opportunity is defined for each time slot), while the SSSG indices associated with row indices 3 and 4 (and therefore with repetition counts of n3 and n4 respectively; also multi-TTI transmission) are different SSS groups, SSSG 1 (e.g., assuming fewer PDCCH monitoring opportunities, e.g., every 4th time slot)). For example, if row 2 is indicated in the DCI at time slot n, the UE still monitors each time slot (i.e., remains in SSSG 0), even though PDCCH repetitions are scheduled for time slot n and time slot n+1.

[0273] Furthermore, this gives the gNB the opportunity to send another DCI in slot n+1 to schedule another PDSCH using, for example, row index 1. This would be possible because in slot n+1, the two PDSCHs are sent on different frequency resources, even though they both span the same number of symbols in time.

[0274] It should also be noted that in the exemplary TDRA table above, for entry 3, one DCI schedules 3 transmissions, but the UE monitors the PDCCH every 4th time slot, i.e., remains in SSSG 1. For example, the gNB does not want to switch SSS groups but wants to temporarily reduce the number of repetitions, for example, in the case of improved channel conditions, or when the data in the buffer for the UE is insufficient to accommodate n3 transmissions.

[0275] A further variation of the second solution incorporates the use of handover time as an additional mechanism for switching between different SSS groups. This can be useful if the UE misses a scheduling DCI carrying an SSSG indication. Generally, the UE determines a new SSS group for performing surveillance functions after the handover time period expires, where the handover time period begins when monitoring of the downlink control channel has started according to the currently used SSS group.

[0276] When more than two SSS groups are available for the improved PDCCH monitoring procedure, a time-based handover mechanism can also be used. In this case, after the time expires, the UE can use the default (or initial) SSSG, or another fixed SSSG (which differs from the default SSSG among the various SSSGs), or the SSS group previously used by the UE in the currently used SSSG (causing the handover time to begin).

[0277] Therefore, such a switchover time provides another possibility for how to change between SSS groups, and can be implemented for one, some, or all possible SSS group conversions. For example, as will be combined below Figure 25 and 26 As explained, time-based handover can only be used to switch back to the default SSS group 0, but not to switch from SSS group 0 to another SSS group (such as SSSG1). However, this is just an example, and the UE may switch to another, predetermined SSS group or switch to the previously used SSS group after the handover period expires.

[0278] In addition, according to an exemplary implementation, the UE can use a timer to monitor the switching time period.

[0279] Figure 25 This is a flowchart illustrating the UE behavior of an exemplary implementation of a timer-based variant for the second solution. Furthermore, Figure 26 It is the UE's state diagram, similar to... Figure 24 and 25 The implementation scheme. In both cases, it is exemplarily assumed that the UE starts monitoring the PDCCH based on the default SSSG 0, ​​which can, for example, provide dense or sparse monitoring timing.

[0280] from Figure 25Obviously, when the SSS group is determined based on the determined SSS group and PDCCH monitoring is performed, the UE also starts a handover timer. When the handover timer expires (and assuming that no scheduling DCI indicating SSSG 0 is received in the UE before the handover timer expires), the UE switches back to monitoring PDCCH based on the default SSSG 0.

[0281] Figure 26 Similarly, the state transition between "Monitoring SSSG 0" and "Monitoring SSSG 1" is illustrated. It is obvious that a state transition from the non-default SSSG 1 to the default SSSG 0 based on timer expiration is also possible (see also...). Figure 25 ).also, Figure 26 The option to restart the handover timer when the same SSSG 1 is directed again is shown, thereby extending the time period during which the UE keeps monitoring the downlink control channel based on SSSG 1.

[0282] According to a further variant of the second solution, at least some of all SSS groups are respectively used to receive DCI messages assigned a different number of send / receive.

[0283] For example, assuming two SSS groups, the specific configuration of each SSS group explicitly associates one SSS group with, for example, single-TTI scheduling, and explicitly associates the other SSS group with, for example, multi-TTI scheduling. Accordingly, the scheduling DCI for a single-TTI will be sent by the base station during the monitoring period defined by the corresponding single-TTI-related SSS group. Conversely, the scheduling DCI for a multi-TTI will be sent by the base station during the monitoring period defined by the corresponding multi-TTI-related SSS group.

[0284] In the case of more than two SSS groups, an exemplary solution is to consider a multi-TTI scheduling granularity, where one SSS group is used to carry a scheduling DCI that allocates the same (or similar) number of transmit / receive. For example, SSSG 0 always schedules single-TTI transmit / receive, SSSG 1 always schedules multi-TTI with 2 transmit / receive, and SSSG 2 always schedules multi-TTI with 3 transmit / receive.

[0285] As a possible complement, single-TTI-related SSS groups would define relatively dense monitoring timings to allow for good flexibility for possible subsequent single-TTI scheduling. On the other hand, multi-TTI-related SSS groups would define relatively sparse monitoring timings (e.g., depending on the scheduling granularity of multi-TTI scheduling), thereby allowing the UE to save power by skipping PDCCH monitoring in some time slots.

[0286] In this way, the PDCCH monitoring periodicity of different SSS groups will be well matched with the scheduling granularity of the corresponding scheduling DCI carried in each SSS group.

[0287] With such an SSS group configuration, the implicit indication for switching between different SSS groups discussed in the first solution above is difficult to implement because when the UE monitors according to an SSS group, the UE will only receive the scheduling DCI related to that SSS group, but not the scheduling DCI related to other SSS groups, which will implicitly trigger a switch to those other SSS groups (see the first solution). Figure 18 On the other hand, a second solution that provides explicit indication of SSS groups can be well utilized. For example, a single-TTI scheduling DCI can identify SSS groups associated with multi-TTIs for future PDCCH monitoring, so that the base station can then send a multi-TTI scheduling DCI.

[0288] The second solution (and its variations) described above can also be implemented at the base station. As already broadly mentioned above, the base station performs steps corresponding to those on the UE side to allow the base station to determine how the UE monitors the PDCCH and then be able to perform operations accordingly (e.g., send the next scheduling DCI).

[0289] In this second solution, specifically for the first variant using an explicit SSSG field, the base station behavior therefore includes determining the SSS group that the UE will subsequently use to perform PDCCH monitoring functions. According to the first variant of the second solution, the base station then sets the SSSG field of the scheduled DCI to a specific value corresponding to the determined future SSS group.

[0290] The step of determining the future SSS group that the UE will use is not required but can be performed on a second variant of the second solution, such that, taking into account the determined future SSS group, a suitable set of time-domain scheduling parameters (and the associated SSS group) is determined. The base station then sets the resource allocation field of the scheduling DCI to a specific value corresponding to the determined set of time-domain scheduling parameters.

[0291] Unlike the first solution (and the third solution presented below), the switching of SSS groups occurs as a direct result of the scheduling decision made by the base station. The separate step of determining the SSS group the UE will use in the future does not need to be performed at the base station. For example, when scheduling a single-TTI transmit / receive, the corresponding SSS group is automatically associated, eliminating the need for separate SSS group determination; similarly, this applies when the base station determines a multi-TTI transmit / receive. Nevertheless, the base station can know how the UE monitors the PDCCH, specifically based on which SSS group, in order to deliver the DCI to the UE when necessary.

[0292] In the context of the second solution, particularly for a second variant based on a properly configured set of time-domain scheduling parameters, the base station may be responsible for defining these time-domain scheduling parameter sets and configuring the UE accordingly. Therefore, the base station generates appropriate configuration messages (e.g., as part of the RRC layer) and sends them to the UE. Thus, the UE has appropriate information that can be used later for scheduling along with the resource allocation field to identify the time-domain scheduling parameters and the guided SSS group. Generally, the configuration information provides the UE with the association between different SSS groups and the different values ​​of the resource allocation field for scheduling the DCI.

[0293] In specific implementations, base stations define TDRA tables using RRC messages (see, for example, the 5G NR standard discussion).

[0294] Accordingly, since the base station independently and proactively determines the SSS group that the UE should use in the future, it should always know how the UE monitors the PDCCH, especially based on which SSS group.

[0295] In other time-based variants of the second solution, the behavior of the base station is therefore also incorporated into the monitoring of the handover time period (and optionally into the operation of a timer to monitor the handover time period) in order to determine when the UE will hand back to another SSS group after the handover time period expires.

[0296] The third solution - explicit indication of SSS groups based on the priority of scheduled data.

[0297] The third solution (and its variants) will be presented below, regarding how the UE determines the SSSG that should be used for the PDCCH monitoring function based on the scheduling DCI.

[0298] The third solution is based on the priority of data scheduled by the DCI. Accordingly, the UE determines the priority of the data to be transmitted / received assigned by the scheduling DCI, and then, based on the priority, determines which data will be used for the monitoring function SSS group.

[0299] The exemplary implementation distinguishes between high-priority and low-priority data traffic. Priority may be related to one or more specific traffic characteristics, such as latency requirements.

[0300] For example, high-priority data traffic might be, for instance, URLLC data, where low latency requirements benefit from SSS groups with relatively dense monitoring opportunities. Conversely, low-priority data traffic might be, for instance, eMBB data, where relaxed latency requirements allow for relatively sparse monitoring opportunities for SSS groups (and thus allow for power-saving opportunities).

[0301] Therefore, the UE performs PDCCH monitoring based on SSS groups that match the priority and characteristics (such as latency requirements) of the scheduled data traffic.

[0302] According to the corresponding exemplary UE behavior of this third solution Figure 27 As shown, the UE first determines the priority of the data scheduled by the DCI message, and then proceeds to determine the SSS group corresponding to the determined priority. PDCCH monitoring is then performed according to the determined SSS group.

[0303] There are several possibilities for how a UE can determine the data transmission / reception priority assigned by the scheduling DCI. For example, the priority can be independent of whether the scheduling DCI schedules single-TTI transmission / reception or multi-TTI transmission / reception.

[0304] In a first variant of the third solution, the scheduling DCI may include a suitable priority field that directly indicates the assigned priority and thus allows the derivation of the SSS group associated with that priority.

[0305] According to a second variant of the third solution, priority can be deduced by the UE based on the format of the scheduled DCI. For example, the scheduled DCI can be sent in different formats, where these formats are associated with different priorities. In an exemplary implementation conforming to the 5G NR standard, URLLC traffic can be scheduled using a DCI message of format 1_2, and eMBB traffic can be scheduled using a DCI message of format 1_0 or 1_1. Therefore, when the UE determines that the format of the decoded DCI message is 1_2, it will deduce that the scheduled traffic is high priority (URLLC) and will use a suitable SSS group with dense monitoring timing. When the UE determines that the format of the decoded DCI message is 1_0 or 1_1, it will deduce that the scheduled traffic is low priority (eMBB) and will use a suitable SSS group with sparse monitoring timing.

[0306] In any variant, the UE has appropriate available information to derive the SSS group from the determined data traffic priorities of the scheduled DCI. This information may, for example, be fixed in the standard, or may be provided by the base station in a configuration message (e.g., using RRC).

[0307] The third solution (and its variations) described above can also be implemented at the base station. As generally mentioned above, the base station performs steps corresponding to those on the UE side to allow the base station to determine how the UE monitors the PDCCH and then perform operations accordingly (e.g., send the next scheduling DCI).

[0308] In the current third solution, the base station can simply determine the priority of the traffic scheduled for the UE in order to deduce (in a manner corresponding to the UE) which SSS group the UE will use to perform its monitoring functions (and therefore how to schedule future transmissions of DCI).

[0309] According to a first variant of the third solution, the base station determines the priority of the data it wants to allocate by scheduling the DCI, and then sets the priority field of the scheduling DCI accordingly. As explained above, this allows the UE to identify the priority of the allocated data transmission / reception based on the priority field.

[0310] According to a second variant of the third solution, the base station generates a scheduling DCI based on a suitable format indicating the priority of data allocation. The base station then performs a corresponding priority determination based on the format of the previously transmitted scheduling DCI to identify the SSS group that the UE is currently monitoring.

[0311] Further variants

[0312] Numerous variations and implementations of improved downlink channel monitoring procedures have been described. For example, three different solutions (and their respective variations) have been described regarding how a UE can determine which SSS group it should use to implement monitoring functions based on the content or format of the scheduled DCI. Some of these variations or implementations have been described separately to aid in understanding the underlying mechanisms and benefits of each variation or implementation.

[0313] Depending on further solutions, the UE can support some or all of the solutions discussed above to form new variations and implementations of the improved procedure. Several of these combinable implementations are listed below without exhaustiveness.

[0314] In one exemplary implementation, the UE can be initially configured (e.g., by the base station) to perform an improved downlink channel monitoring procedure based on one of the solutions (or variants). The UE can then be reconfigured as needed.

[0315] Alternatively, the UE may operate under more than one solution (or a variant thereof) simultaneously. For example, the UE may be able to follow explicit instructions for the SSS group (see the second solution) but additionally follow implicit handover based on a single-vs-multiple-TTI solution (see the first solution). Other combinations of solutions are equally possible.

[0316] Such a combination of two or more solutions can be beneficial, for example, when there are more than two SSS groups. According to one such exemplary implementation, the UE can follow implicit handover based on only two of the various SSS groups (e.g., handover between single-TTI related SSSGs and multi-TTI related SSSGs). On the other hand, one or more of the remaining SSS groups can be used by the US when explicitly instructed by the base station, for example, using explicit signaling of a second solution (and its implementations and variations).

[0317] In the above solution, it is assumed that the UE performs a monitoring function on the downlink control channel (e.g., the PDCCH in the 3GPP implementation solution) used to receive DCI messages from the base station. According to a further exemplary solution that can be combined with other solutions, based on this improved PDCCH monitoring procedure, the UE's scheduled DCI for monitoring the PDCCH is typically transmitted in a UE-specific search space or in a type 3 common search space (see Section 10.1 of TS 38.213 v16.1.0 for the definition of different types of common search spaces). Other common search spaces, such as type-0, type-0A, type-1, and type-2 used for the transmission of broadcast system information, are monitored independently of these search spaces and independently of the SSSG handover explained above (e.g., for receiving broadcast PDCCH).

[0318] Further exemplary solutions, which can be combined with other solutions, can define further restrictions on SSS groups, such as different SSS groups being defined on the same control resource set (CORESET). Furthermore, the sparse monitoring timing defined for one SSS group may be a subset of the dense monitoring timing for another SSS group within the same CORESET. Such definitions of SSS groups and their monitoring timings facilitate error recovery. For example, consider a scenario where the UE misses a scheduling DCI carrying an explicit group handover indication, e.g., due to channel fading. As a result, the base station and the UE may have different understandings of which SSSG to use. To address this uncertainty, the base station can send a new DCI at the PDCCH monitoring timing occurring in both SSSGs (i.e., overlapping timings between different SSSGs). Regardless of which SSSG the UE is currently monitoring, the UE is able to receive the new DCI. By decoding the new DCI, the UE knows the SSSG indication from the base station. Thus, the potential mismatch problem is resolved.

[0319] According to further exemplary solutions that can be combined with other solutions, the improved PDCCH monitoring procedure can be applied to only a single serving cell of the UE, or alternatively, to specific or all serving cells (e.g., within a cell group). This can, for example, be configured by the base station with a corresponding configuration (e.g., via RRC).

[0320] Some of the solutions and variations of the improved PDCCH monitoring procedure described above mention a default SSS group, which the UE initially uses to begin performing monitoring functions. For example, a default SSSG can be applied immediately after the SSG is configured (e.g., via RRC). Other exemplary conditions regarding when to use a default SSSG may include the following:

[0321] • By default, SSSG can be used at the start of the DRX cycle (e.g., when the On Duration timer starts).

[0322] • The default SSSG can be used during wake-up triggered by DCI format 2_6, meaning that the UE resumes PDCCH monitoring after the sleep period.

[0323] • When operating in an unlicensed frequency band, the SSSG can be used by default at the beginning of the channel occupancy period.

[0324] • The default SSSG can be used when a timer expires, for example, the timer can be a timer that is disabled or toggled as mentioned in the previous solution.

[0325] DRX operation can also be considered based on further exemplary solutions that can be combined with other solutions. In short, Discontinuous Reception (DRX) is a mechanism to minimize the time the UE spends monitoring the PDCCH, thereby reducing battery consumption. The DRX function defines a DRX period (during which the UE is not required to monitor the PDCCH) and an active period (during which the UE is required to fulfill its PDCCH monitoring requirements). Defining the DRX function involves defining many parameters, timers, etc., such as OnDuration, DRX Inactivity Timer, DRX Short Period, and DRX Long Period. The standardization of 5G NR has already defined DRX in Section 5.7 of 3GPP TS38.321 v16.0.0, titled "Discontinuous Reception (DRX)".

[0326] According to the first implementation scheme, the improved PDCCH monitoring procedure does not affect the DRX function running by the UE. For example, the parameters and timers of the DRX function are not compatible with or are out of sync with the improved PDCCH monitoring procedure.

[0327] According to another implementation, some of the DRX-related timers and / or parameters are continuously adjusted based on the SSSG currently used by the UE to perform surveillance functions. For example, the timer value is scaled according to the PDCCH surveillance periodicity of the currently used SSSG. More specifically, as an example, two SSSGs are configured: SSSG 0 has a PDCCH surveillance periodicity of 4 slots, and SSSG 1 has a PDCCH surveillance periodicity of 1 slot. Therefore, the DRX inactivity timer has two configured values, 4n and n, corresponding to the different SSSGs respectively. The purpose of the DRX inactivity timer is to define the duration during which the UE will enter sleep mode after its expiration if no PDCCH is received. Since the PDCCH surveillance requirements are different between SSSG 0 and SSSG 1, scaling the DRX inactivity timer accordingly, as described, is more in line with the original purpose of the timer.

[0328] Whether the DRX function is adapted / synchronized with the improved PDCCH monitoring function can be fixed in the 3GPP standard or can be configured by the base station (e.g., using RRC messages).

[0329] In variations of the first and second solutions described above, time (and optional timers) is used to further improve the SSSG switching operation. According to further variations, the time (and optional timers) can be specifically configured as described below.

[0330] Timer values ​​can be configured per serving cell (or per serving cell group if a cell group is configured). Therefore, only a single timer value needs to be maintained across different SSSGs.

[0331] The timer value will be decremented (or incremented) as long as a non-default SSSG is being monitored (e.g., in time slots of the reference SCS (subcarrier spacing)) (e.g., unless the timer restart condition is met).

[0332] Alternatively, timer values ​​can be configured by bandwidth portion or by non-default SSSG, which offers more flexibility, but at the cost of the complexity of the UE (and the base station) needing to track multiple timers. In this case, the timer value is decremented (or incremented) (e.g., by the time slot of the SCS using the monitored SSSG (or by TTI)) (unless the timer restart condition is met).

[0333] Further aspects

[0334] According to the first aspect, a user equipment (UE) is provided, comprising the following: A processor of the UE operates a monitoring function involving monitoring a downlink control channel for receiving downlink control information messages based on one of a plurality of search space sets. A receiver of the UE receives downlink control information messages via the monitored downlink control channel, wherein the received downlink control information messages assign data transmission or reception to the UE. The processor also determines one of the plurality of search space sets for performing the monitoring function of the downlink control channel. The determination of the search space set is based on:

[0335] • The content or format of the received downlink control information messages.

[0336] Based on the second aspect provided in addition to the first aspect, it is determined that the search space set used to perform the monitoring function is executed by the processor based on the following:

[0337] • The base station assigns the amount of data to be sent or received by the UE through the content of the downlink control information message.

[0338] In an optional implementation, when the number of transmissions or receptions is one, the search space group is determined to have a short periodicity with the required monitoring timing. When the number of transmissions or receptions is greater than one, the search space group is determined to have a long periodicity with the required monitoring timing. In a further optional implementation, when determining the search space group for performing the monitoring function, the processor determines a search space group with a periodicity with the required monitoring timing corresponding to the number of transmissions or receptions allocated by the downlink control information message.

[0339] According to a third aspect provided in addition to the second aspect, after the processor has determined the currently used search space set based on the number of transmissions or receptions, it prohibits determining a search space set different from the currently used search space set during a prohibition period. In an alternative embodiment, the processor starts a prohibition timer when it determines that a search space set different from the currently used search space set is being used to perform the monitoring function. After starting the prohibition timer and during the prohibition timer's runtime, the processor does not determine the use of a search space set different from the currently used search space set. In a further alternative embodiment, the prohibition timer is restarted each time the processor determines a search space set that caused the prohibition timer to start and is used to perform the monitoring function.

[0340] According to a fourth aspect provided in addition to one of the first to third aspects, at least two of the plurality of search space groups have different periodicities regarding the required monitoring timing of the downlink control channel to be monitored by the user equipment. The determination of one search space group identifies one of the at least two search space groups to perform the monitoring function based on the different periodicities of the required monitoring timing. In an alternative embodiment, one of the plurality of search space groups is configured as a default search space group. Further alternatively, the default search space group is initially used to perform the monitoring function; in a further alternative embodiment, the default search space group is a search space group with either a short periodicity or a long periodicity of the required monitoring timing.

[0341] Based on a fifth aspect provided in addition to one of the first to fourth aspects, the set of search spaces used to perform the monitoring function is determined by the processor based on the following:

[0342] • The processor determines the identifier of the search space set group to be used to perform the monitoring function based on the field of the downlink control information message content.

[0343] This field can be either a search space set field, identifying the search space set to be used to perform the monitoring function, or a resource allocation field, indicating time-domain scheduling parameters related to the allocated transmission or reception. The indicated time-domain scheduling parameters also identify the search space set to be used to perform the monitoring function. In an alternative implementation, the processor determines one set of multiple time-domain scheduling parameters from a time-domain resource allocation table based on the value of the resource allocation field in the downlink control information. Each set of time-domain scheduling parameters is associated with a search space set.

[0344] According to a sixth aspect provided in addition to the fifth aspect, the processor determines a different search space set than the currently used search space set for performing the monitoring function after the switching time period expires. The switching time period begins when the current search space set is started. In an alternative embodiment, the determined different search space set is either the default search space set or a search space set previously used in the currently used search space set. In a further alternative embodiment, the processor runs a switching timer for the switching time period.

[0345] According to a seventh aspect provided in addition to one of the fifth or sixth aspects, at least some of the plurality of search space sets are respectively used to monitor downlink control channels for receiving different numbers of downlink control information messages respectively indicating that the base station has allocated a transmission or reception to the UE. In an alternative embodiment, one set of the plurality of search space sets is used only to monitor downlink control channels for receiving only one downlink control information message indicating that the base station has allocated a transmission or reception to the UE. Another set of the plurality of search space sets is used only to monitor downlink control channels for receiving more than one downlink control information message indicating that the base station has allocated a transmission or reception to the UE.

[0346] Based on an eighth aspect provided in addition to one of the first to seventh aspects, the set of search spaces used to perform the monitoring function is determined by the processor based on the following:

[0347] • The priority of the data being sent or received, assigned by the downlink control information message.

[0348] In an optional implementation, the data priority is indicated by a data priority field in the downlink control information message. In a further optional implementation, the UE has information regarding the association of different data priorities and different search space sets. In yet another optional implementation, the processor determines the data priority based on the format of the downlink control information message.

[0349] According to a ninth aspect provided in addition to one of the first to eighth aspects, the monitoring function is performed on a time-slot basis or on a mini-time-slot basis. In an optional implementation, the mini-slot spans one or more OFDM symbols, but fewer than the time-slots.

[0350] According to a tenth aspect provided in addition to one of the first to ninth aspects, the UE operates a discontinuous reception DRX function, including at least one DRX-related timer. The processor adjusts the at least one DRX-related timer based on the periodicity of the required monitoring timing for the downlink control channel of the currently used search space set for performing the monitoring function, such as based on the search space set currently in use. Alternatively, the processor does not adjust the at least one DRX-related timer based on the search space set currently in use for performing the monitoring function. In an alternative embodiment, whether the at least one DRX-related timer is adjusted or not based on the currently used search space set is determined by the processor based on a configuration received from the base station.

[0351] According to the eleventh aspect, which is provided in addition to one of the first to tenth aspects, the monitoring function may be performed for a single serving cell of the UE or for multiple serving cells of the UE. In an alternative implementation, the processor determines whether to perform the monitoring function for a single serving cell or for multiple serving cells based on the configuration received from the base station.

[0352] According to the twelfth aspect, which is provided in addition to the third and sixth aspects, the prohibition time period, and optionally the prohibition timer, are configured on a per-serving cell, per-search-space-group, or per-bandwidth portion. The handover time period, and optionally the handover timer, are configured on a per-serving cell, per-search-space-group, or per-bandwidth portion.

[0353] According to a thirteenth aspect provided in addition to one of the first to twelfth aspects, the downlink control information message allocates downlink radio resources for the UE to receive the data, optionally wherein the downlink control information message is in the format of format 1_0, format 1_1, or format 1_2. The downlink control information message allocates uplink radio resources for the UE to transmit the data, optionally wherein the downlink control information message is in the format of format 0_0, format 0_1, or format 0_2.

[0354] According to the fourteenth aspect, a method is provided. The method includes the following steps performed by a user equipment (UE): The UE operates a monitoring function involving monitoring a downlink control channel for receiving downlink control information messages based on one of a plurality of search space sets. The UE receives downlink control information messages via the monitored downlink control channel, wherein the received downlink control information messages assign data transmission or reception to the UE. The UE determines one of the plurality of search space sets for performing the monitoring function on the downlink control channel. The determination of the search space set is based on the content or format of the received downlink control information messages.

[0355] According to a fifteenth aspect, a base station is provided comprising the following: A processor of the base station generates downlink control information messages. The generated downlink control information messages assign data transmission or reception to a UE. The content or format of the generated downlink control information messages enables the UE to determine one of a plurality of search space sets used by the UE to perform a monitoring function involving monitoring a downlink control channel for receiving downlink control information messages. The processor determines the search space set currently used by the UE to perform the monitoring function. The determination of the currently used search space set is based on the content or format of another downlink control information message previously sent to the UE. A transmitter of the base station, based on the determined currently used search space set, transmits the generated downlink control information messages to the UE via the downlink control channel.

[0356] According to the sixteenth aspect, which is provided in addition to the fifteenth aspect, the determination of the currently used search space set is performed by the processor based on the following:

[0357] The base station assigns the number of transmissions or receptions to the UE based on the content of the previously sent downlink control information message.

[0358] In an optional implementation, the determination of the currently used search space set is performed by the processor based on the following:

[0359] • Prohibited time period: During which the user equipment is prohibited from determining a second search space group that is different from the first search space group after the first search space group has been determined based on the number of transmissions or receptions.

[0360] According to the seventeenth aspect, in addition to the fifteenth aspect, the processor determines one of the plurality of search space sets used by the user equipment to perform a monitoring function involving monitoring a downlink control channel for receiving downlink control information messages. The processor sets a search space set field for the content of the downlink control information message to identify the determined search space set.

[0361] According to the eighteenth aspect, in addition to the fifteenth aspect, the transmitter sends a configuration message to the UE, which provides information about different values ​​of the resource allocation field and the associations between different groups in the plurality of search space sets. The transmitted downlink control information message includes the resource allocation field, which has values ​​indicating time-domain scheduling parameters associated with the allocated transmission or reception. In an optional implementation, the configuration information provides information about a time-domain resource allocation table that defines different sets of time-domain scheduling parameters for different values ​​of the resource allocation field.

[0362] According to the nineteenth aspect, which is provided in addition to the seventeenth or eighteenth aspect, the determination of the currently used search space set is performed by the processor based on the following:

[0363] • The switching time period is initiated when the first search space group is used, wherein after the switching time period expires, the UE determines a different search space group than the first search space group for performing the monitoring function.

[0364] Based on aspect 20, which is provided in addition to aspect 15 to aspect 19, the determination of the currently used search space set is performed by the processor based on the following:

[0365] • The priority of the transmitted or received data assigned by the previously sent downlink control information message.

[0366] In an optional implementation, the processor determines the priority of the transmitted or received data to be allocated by the downlink control message. The processor then sets a data priority field in the downlink control message based on the determined priority.

[0367] According to aspect 21, a method is provided including the following steps performed by a base station. The base station generates a downlink control information message, wherein the generated downlink control information message assigns the transmission or reception of data to a UE. The content or format of the generated downlink control information message enables the UE to determine one of a plurality of search space sets used by the UE to perform a surveillance function involving monitoring a downlink control channel for receiving downlink control information messages. The base station determines the search space set currently used by the UE to perform the surveillance function. The determination of the currently used search space set is based on the content or format of another downlink control information message previously sent to the UE. Based on the determined currently used search space set, the base station sends the generated downlink control information message to the UE via the downlink control channel.

[0368] According to aspect 22, an integrated circuit is provided that controls a user equipment process, the process including the following steps performed by the user equipment:

[0369] The monitoring function involves monitoring the downlink control channel used for receiving downlink control information messages based on one of multiple search space sets.

[0370] Downlink control information messages are received via the monitored downlink control channel, whereby the received downlink control information messages assign data transmission or reception to the UE.

[0371] Determine one of the plurality of search space sets used to perform the monitoring function of the downlink control channel, wherein the determination of the search space set is based on:

[0372] • The content or format of the received downlink control information messages.

[0373] According to aspect 23, an integrated circuit is provided that controls a base station process, the process including the following steps performed by the base station:

[0374] A downlink control information message is generated, wherein the generated downlink control information message assigns data transmission or reception to the UE, and wherein the content or format of the generated downlink control information message enables the user equipment to determine one of a plurality of search space sets used by the user equipment to perform a monitoring function involving monitoring the downlink control channel used to receive downlink control information messages.

[0375] The search space set currently used by the user equipment to perform the monitoring function is determined from among the multiple search space sets, wherein the determination of the currently used search space set is based on the content or format of another downlink control information message previously sent to the user equipment, and

[0376] Based on the determined set of search space currently in use, the generated downlink control information message is sent to the user equipment via the downlink control channel.

[0377] The hardware and software implementation schemes of this disclosure

[0378] This disclosure can be implemented by software, hardware, or a combination of software and hardware. Each functional block used in the description of each of the above embodiments can be implemented partially or entirely by an LSI such as an integrated circuit, and each process described in each embodiment can be controlled partially or entirely by the same LSI or a combination of LSIs. An LSI can be formed as a single chip, or it can be formed as a single chip to include some or all of the functional blocks. An LSI can include data inputs and outputs coupled thereto. Depending on the degree of integration, the LSI here can be referred to as an IC (integrated circuit), a system LSI, a super LSI, or an ultra-LSI. However, the technology for implementing integrated circuits is not limited to LSIs and can be implemented using dedicated circuits, general-purpose processors, or application-specific processors. Additionally, FPGAs (Field-Programmable Gate Arrays) programmed after LSI fabrication or reconfigurable processors that can reconfigure the connections and settings of circuit cells arranged within an LSI can be used. This disclosure can be implemented as digital or analog processing. If future integrated circuit technology replaces the LSI due to advancements in semiconductor technology or other derivative technologies, then future integrated circuit technology can be used to integrate the functional blocks. Biotechnology can also be applied.

[0379] This disclosure can be implemented by any kind of communication device, apparatus or system, which is called a communication device.

[0380] The communication device may include a transceiver and processing / control circuitry. The transceiver may include a receiver and a transmitter and / or function as both a receiver and a transmitter. A transceiver acting as a transmitter and receiver may include an RF (radio frequency) module comprising an amplifier, an RF modulator / demodulator, etc., and one or more antennas.

[0381] Some non-limiting examples of such communication devices include telephones (e.g., cellular phones, smartphones), tablets, personal computers (PCs) (e.g., laptops, desktops, netbooks), cameras (e.g., digital still / video cameras), digital players (digital audio / video players), wearable devices (e.g., wearable cameras, smartwatches, tracking devices), game consoles, digital book readers, remote healthcare / telemedicine (remote healthcare and medical) devices, and vehicles that provide communication functionality (e.g., cars, airplanes, ships), and various combinations thereof.

[0382] Communication devices are not limited to portable or mobile devices, but may also include any kind of non-portable or fixed device, equipment or system, such as smart home devices (e.g., appliances, lighting, smart meters, control panels), vending machines, and any other “thing” in an “Internet of Things” network.

[0383] Communication may include exchanging data through, for example, cellular systems, wireless LAN systems, satellite systems, and various combinations thereof.

[0384] The communication device may include a device such as a controller or sensor coupled to a communication device that performs the communication functions described in this disclosure. For example, the communication device may include a controller or sensor that generates control signals or data signals used by the communication device performing the communication functions of the communication device.

[0385] The communication apparatus may also include infrastructure such as base stations, access points, and any other apparatus, device, or system that communicates with or controls apparatuses such as those in the non-limiting examples above.

[0386] Furthermore, various embodiments can also be implemented using a software module approach, which is executed by a processor or directly in the hardware. A combination of software modules and hardware implementation is also possible. The software module can be stored on any type of computer-readable storage medium, such as RAM, EPROM, EEPROM, flash memory, registers, hard disk, CD-ROM, DVD, etc. It should be further noted that various features of different embodiments can individually or arbitrarily combine to form the subject matter of another embodiment.

[0387] Those skilled in the art will understand that many variations and / or modifications can be made to this disclosure as illustrated in the specific embodiments. Therefore, these embodiments should be considered illustrative in all respects and not restrictive.

Claims

1. A communication device, comprising: a processor, the processor running a monitoring function, the monitoring function involving monitoring a downlink control channel, a receiver, the receiver receiving a downlink control information message via the monitored downlink control channel, wherein the received downlink control information message schedules transmission or reception of data to the communication device, wherein, in a first case where the received downlink control information message comprises a search space set group, SSSG, field with more than one bit, the processor determines, based on the received downlink control information message comprising the SSSG field with more than one bit, a SSSG from more than two SSSGs for performing the monitoring function of the downlink control channel, and in a second case where the received downlink control information is associated with one of more than two durations, the processor configures the communication device to skip the monitoring function for a duration based on the received downlink control information associated with one of the more than two durations.

2. The communication device of claim 1, wherein determining the one SSSG for performing the monitoring function is performed by the processor based on: • a number of transmissions or receptions scheduled to the communication device by a base station through the downlink control information message.

3. The communication device of one of claims 1 to 2, wherein one of the plurality of SSSGs is configured as a default SSSG, wherein the default SSSG is initially used for performing the monitoring function.

4. The communication device of claim 1, wherein the processor determines, based on the SSSG field, an identity of a SSSG to be used for performing the monitoring function, wherein the SSSG field identifies the SSSG for performing the monitoring function.

5. The communication device of claim 1, wherein the processor determines, after expiration of a switching time period, to switch to a default SSSG for performing the monitoring function different from a currently used SSSG, the switching time period having started when starting to use the current SSSG, wherein the processor runs a switching timer for the switching time period.

6. The communication device of one of claims 1 to 2, wherein the monitoring function is performed on a time slot basis or on a mini time slot basis, wherein a mini time slot spans one or more OFDM symbols but less than a time slot.

7. The communication device of one of claims 1 to 2, wherein the monitoring function is performed for a single serving cell of the communication device or for a plurality of serving cells of the communication device, wherein the processor determines, based on a configuration received from a base station, whether to perform the monitoring function for the single serving cell or for the plurality of serving cells.

8. The communication device of claim 5, wherein the switching time period, and the switching timer, are configured per single serving cell or per each search space group of a SSSG or per bandwidth part.

9. The communication device of one of claims 1 to 2, wherein the downlink control information message schedules downlink radio resources for reception of the data of the communication device, wherein a format of the downlink control information message is format 1_1 or format 1_2, and wherein the downlink control information message schedules uplink radio resources for transmission of the data of the communication device, wherein a format of the downlink control information message is format 0_1 or format 0_2.

10. A method comprising the following steps performed by a communication device: running a monitoring function, the monitoring function involving monitoring a downlink control channel, receiving a downlink control information message via the monitored downlink control channel, wherein the received downlink control information message schedules transmission or reception of data to the communication device, wherein, in a first case where the received downlink control information message comprises a search space set group, SSSG, field with more than one bit, determining, based on the received downlink control information message comprising the SSSG field with more than one bit, a SSSG of more than two SSSGs for performing the monitoring function of the downlink control channel, and in a second case where the received downlink control information is associated with one of more than two durations, configuring, based on the received downlink control information associated with one of more than two durations, a duration of the monitoring function that the communication device skips.

11. A base station comprising: a processor, the processor generating a downlink control information message, wherein the generated downlink control information message schedules transmission or reception of data to a communication device, and wherein based on a configuration, the generated downlink control information message comprises a search space set group, SSSG, field with more than one bit or is associated with one of more than two durations, the processor determining a SSSG of more than two SSSGs that the communication device currently uses for performing a monitoring function, wherein determining the currently used SSSG is based on another downlink control information message previously transmitted to the communication device, and a transmitter, the transmitter transmitting, based on the determined currently used SSSG, the generated downlink control information message to the communication device via a downlink control channel.

12. The base station of claim 11, wherein determining the currently used SSSG is performed by the processor based on: • a number of transmissions or receptions scheduled by the base station to the UE through contents of the previously transmitted downlink control information message.

13. The base station of claim 11, wherein the processor determines a SSSG of the more than two SSSGs that the communication device uses for performing a monitoring function, the monitoring function involving monitoring a downlink control channel for receiving a downlink control information message, and wherein the processor sets the more than one bit SSSG field of the downlink control information message to identify the determined SSSG. ​ ​ 14. The base station of claim 12 or 13, wherein the determination of a currently used SSSG is performed by the processor based on: • a switching time period, initiated at a time of using a first SSSG, wherein after expiry of the switching time period, the communication device determines an SSSG different from the first SSSG for performing the monitoring function.

15. A method, the method comprising the following steps performed by a base station: generating a downlink control information message, wherein the generated downlink control information message schedules transmission or reception of data to a communication device, and wherein based on a configuration, the generated downlink control information message comprises a search space set group, SSSG, field with more than one bit, or is associated with one of more than two time durations, determining an SSSG of more than two SSSGs that the communication device currently uses for performing a monitoring function, wherein the determination of the currently used SSSG is based on another downlink control information message previously transmitted to the communication device, and transmitting the generated downlink control information message to the communication device via a downlink control channel based on the determined currently used SSSG.

16. An integrated circuit controlling a process of a communication device, the process comprising the following steps performed by the communication device: running a monitoring function, the monitoring function involving monitoring a downlink control channel, receiving a downlink control information message via the monitored downlink control channel, wherein the received downlink control information message schedules transmission or reception of data to a communication device, wherein, in a first case where the received downlink control information message comprises a search space set group, SSSG, field with more than one bit, determining an SSSG for performing the monitoring function of the downlink control channel from more than two SSSGs based on the received downlink control information message comprising the SSSG field with more than one bit, and in a second case where the received downlink control information is associated with one of more than two time durations, configuring the communication device to skip a time duration of the monitoring function based on the received downlink control information being associated with one of the more than two time durations.

17. An integrated circuit controlling a process of a base station, the process comprising the following steps performed by the base station: generating a downlink control information message, wherein the generated downlink control information message schedules transmission or reception of data to a communication device, and wherein based on a configuration, the generated downlink control information message comprises a search space set group, SSSG, field with more than one bit, or is associated with one of more than two time durations, determining an SSSG of more than two SSSGs that the communication device currently uses for performing a monitoring function, wherein the determination of the currently used SSSG is based on another downlink control information message previously transmitted to the communication device, and transmitting the generated downlink control information message to the communication device via a downlink control channel based on the determined currently used SSSG.

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