Tracking reference signal assignment

Abstract

A device is provided, which includes at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to perform: determining (multiple) synchronization signal blocks that have been sent in a serving cell; receiving group information of tracking reference signals, the group information including an indication of (multiple) synchronization signal blocks for which tracking reference signals have been configured in the serving cell; receiving mapping information, the mapping information including an indication of how individual tracking reference signals are mapped to a time slot structure; and determining (multiple) time domain positions of (multiple) tracking reference signals of the device based on the group information and the mapping information.

Description

Technical Field

[0001] Various example embodiments relate to allocation of tracking reference signals, such as in beam-based unlicensed operation. Background Art

[0002] The New Radio (NR) physical layer channels in Release 15 have been designed to be optimized for the frequency range below 52.6 GHz. Release 16 aims to enable and optimize 3GPP NR systems to operate in the frequency range above 52.6 GHz. Currently, the 60 GHz millimeter wave (mmWave) unlicensed / licensed band (57-71 GHz) is the available International Mobile Telecommunications (IMT) band above 52.6 GHz. Regulatory conditions such as the amount of available spectrum, coexistence scenarios, maximum effective isotropic radiated power (EIRP), opportunities for licensed band operation vary according to the region. For example, in the European Union, the band of 57-66 GHz can be used for unlicensed band operation, while the band of 66-71 GHz can be used for both unlicensed and licensed band operations.

[0003] The European Telecommunications Standards Institute (ETSI) sets regulations for, for example, transmit power and EIRP for different frequency bands. Due to the rather limited EIRP proposed by these regulations, a relatively small number of antenna elements can be used at the network nodes. The result of a smaller number of antenna elements is a wide antenna radiation pattern, i.e. a beam. As the beam becomes wider, the likelihood of inter-beam interference or collisions increases, so a fair spectrum sharing channel access mechanism is needed. One such mechanism is listen-before-talk (LBT). However, in mmWave, LBT may prevent the transmission of periodic tracking reference signals (TRS), which may have a negative impact on the communication between user equipment and network nodes.

[0004] Therefore, there is a need for robust Tracking Reference Signal (TRS) transmission. Summary of the invention

[0005] According to some aspects, the subject matter of independent claims is provided. Some example embodiments are defined in the dependent claims. The scope of protection sought by the various example embodiments is specified by the independent claims. The example embodiments and features (if any) described in this specification that do not fall within the scope of the independent claims will be interpreted as examples that help understand the various example embodiments.

[0006] According to a first aspect, a device is provided, which includes at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to perform: determining (multiple) synchronization signal blocks that have been sent in a serving cell; receiving group information of a tracking reference signal, the group information including an indication of (multiple) synchronization signal blocks for which tracking reference signals have been configured in the serving cell; receiving mapping information, the mapping information including an indication of how individual tracking reference signals are mapped to a time slot structure; and determining (multiple) time domain positions of (multiple) tracking reference signals of the device based on the group information and the mapping information.

[0007] According to a second aspect, a device is provided, which includes at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the device to perform: sending group information of a tracking reference signal, the group information including an indication of (multiple) synchronization signal blocks for which tracking reference signals have been configured in a serving cell; and sending mapping information including an indication of how individual tracking reference signals are mapped to a time slot structure.

[0008] According to a third aspect, a method is provided, comprising: determining (multiple) synchronization signal blocks that have been sent in a serving cell; receiving group information of a tracking reference signal, the group information comprising an indication of (multiple) synchronization signal blocks for which tracking reference signals have been configured in the serving cell; receiving mapping information, the mapping information comprising an indication of how individual tracking reference signals are mapped to a time slot structure; and determining (multiple) time domain positions of (multiple) tracking reference signals of a device based on the group information and the mapping information.

[0009] According to a fourth aspect, a method is provided, comprising: sending group information of a tracking reference signal, the group information comprising an indication of (multiple) synchronization signal blocks for which tracking reference signals have been configured in a serving cell; and sending mapping information, the mapping information comprising an indication of how individual tracking reference signals are mapped to a time slot structure.

[0010] According to the fifth aspect, a non-transitory computer-readable medium is provided, which includes program instructions, which, when executed by at least one processor, cause the device to at least perform at least one method of the third aspect and its embodiments or at least one method of the fourth aspect and its embodiments.

[0011] According to a sixth aspect, a computer program is provided, which is configured to cause the method according to at least one of the third aspect and its embodiments or at least one of the fourth aspect and its embodiments to be executed. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The network architecture of the communication system is shown by way of example;

[0013] Figure 2a By way of example, a network node and user equipment operating with narrow beams are shown;

[0014] Figure 2b By way of example, a network node and user equipment operating with a moderate beamwidth are shown;

[0015] Figure 3 A typical quasi-co-site (QCL) configuration for downlink signals and channels is shown by way of example;

[0016] Figure 4 By way of example, a flow chart of a method is shown;

[0017] Figure 5 The group information of the tracking reference signal (TRS) configured in the serving cell is shown by way of example;

[0018] Figure 6 The mapping information of the TRS based on the indication of the group information is shown by way of example;

[0019] Figure 7 By way of example, it is shown that the tracking reference signal is mapped onto the time slot structure when no explicit gaps are required between the transmissions of different beams;

[0020] Figure 8 The mapping of TRS onto the time slot structure is shown by way of example when one symbol gap is required between transmissions of different beams;

[0021] Fig. 9 The signaling between the user equipment and the network node is shown by way of example;

[0022] Fig.10 By way of example, a tracking reference signal with a validation search space is shown;

[0023] Fig.11 A flowchart of a method is shown by way of example; and

[0024] Fig.12 A block diagram of an apparatus is shown by way of example. DETAILED DESCRIPTION

[0025] Figure 1The network architecture of a communication system is shown by way of example. In the following, different exemplary embodiments will be described using a radio access architecture based on Long Term Evolution Advanced (LTE Advanced, LTE-A) or New Radio (NR), also known as the fifth generation (5G), as an example of an access architecture to which the embodiments may be applied, however, the embodiments are not limited to such an architecture. It will be apparent to those skilled in the art that these embodiments may also be applied to other types of communication networks with appropriate components by appropriately adjusting parameters and procedures. Some examples of other options for applicable systems are Universal Mobile Telecommunications (UMTS) Radio Access Network (UTRAN or E-UTRAN), Long Term Evolution (LTE, same as E-UTRA), Wireless Local Area Network (WLAN or WiFi), Worldwide Interoperability for Microwave Access (WiMax), Personal Communications Service (PCS), Wideband Code Division Multiple Access (WCDMA), systems using Ultra-Wideband (UWB) technology, sensor networks, mobile ad hoc networks (MANETs), and Internet Protocol Multimedia Subsystem (IMS), or any combination thereof.

[0026] Figure 1 The example of FIG. 1 shows a portion of an exemplary radio access network. Figure 1User equipment 100 and 102 are shown, which are configured to wirelessly connect to an access node (e.g., gNB, i.e., next generation Node B, or eNB, i.e., evolved Node B (eNodeB)) 104 providing the cell on one or more communication channels in the cell. The physical link from the user equipment to the network node is called the uplink (UL) or reverse link, and the physical link from the network node to the user equipment is called the downlink (DL) or forward link. It should be understood that the network nodes or their functions can be implemented by using any node, host, server, or access point entity suitable for such use. The communication system typically includes more than one network node, in which case the network nodes may also be configured to communicate with each other via wired or wireless links designed for this purpose. These links can be used for signaling purposes. A network node is a computing device configured to control the radio resources of the communication system to which it is coupled. A network node may also be referred to as a base station (BS), an access point, or any other type of interface device including a relay station capable of operating in a wireless environment. The network node includes or is coupled to a transceiver. A connection to an antenna unit is provided from the transceiver of the network node, and the antenna unit establishes a bidirectional radio link to the user equipment. The antenna unit may include multiple antennas or antenna elements. The network node is also connected to the core network 110 (CN or next generation core NGC). According to the system, the counterpart on the CN side may be a serving gateway (S-GW, routing and forwarding user data packets), a packet data network gateway (P-GW) or a mobile management entity (MME) for providing connectivity of the user equipment (UE) to an external packet data network, etc. An example of a network node configured to operate as a relay station is an integrated access and backhaul node (IAB). The distributed unit (DU) portion of the IAB node performs the BS function of the IAB node, while the backhaul connection is performed by the mobile terminal (MT) portion of the IAB node. The UE function may be performed by the IAB MT, and the BS function may be performed by the IAB DU. The network structure may include a parent node, i.e., an IAB donor, which may have a wired connection to the CN and a wireless connection to the IAB MT.

[0027] User equipment or user equipment UE generally refers to a portable computing device including a wireless mobile communication device that operates with or without a user identity module (SIM), including but not limited to the following types of devices: mobile stations (mobile phones), smart phones, personal digital assistants (PDAs), mobile phones, devices using wireless modems (alarm or measurement devices, etc.). Laptops and / or touch screen computers, tablets, game consoles, notebook computers and multimedia devices. It should be understood that user equipment can also be almost exclusively uplink-only devices, examples of which are cameras or video cameras that load images or video clips to the network. User equipment can also be a device with the ability to operate in an Internet of Things (IoT) network, which is a scenario in which objects are provided with the ability to send data over a network without the need for human-to-human or human-to-computer interaction.

[0028] Furthermore, although the apparatus is described as a single entity, different units, processors and / or memory units ( Figure 1 (not all shown) can be implemented inside these devices to achieve their functions.

[0029] 5G enables the use of multiple-input-multiple-output (MIMO) technology on both the UE and gNB side, many more base stations or nodes than LTE (the so-called small cell concept), including macro sites operating in cooperation with smaller stations and employing various radio technologies depending on the service needs, use cases, and / or available spectrum. 5G mobile communications support a wide range of use cases and related applications, including video streaming, augmented reality, different ways of sharing data, and various forms of machine-type applications (such as (massive) machine-type communications (mMTC)), including vehicle safety, different sensors, and real-time control). 5G is expected to have multiple radio interfaces, namely below 7 GHz, cmWave, and mmWave, and can also be integrated with existing legacy radio access technologies such as LTE. The frequency range below 7 GHz may be referred to as FR1, while the frequency range above 24 GHz (or more precisely 24-52.6 GHz) may be referred to as FR2. At least in the early stages, the integration with LTE may be implemented as a system where the macro coverage is provided by LTE and the 5G radio interface access comes from the small cells by aggregation to LTE. In other words, 5G plans to support inter-RAT operability (e.g., LTE-5G) and inter-RI operability (inter-radio interface operability, e.g., sub-7GHz-cmWave, sub-7GHz-cmWave-mmWave). One of the concepts being considered for use in 5G networks is network slicing, where multiple independent and dedicated virtual sub-networks (network instances) can be created within the same infrastructure to operate services with different requirements for latency, reliability, throughput, and mobility.

[0030] The communication system can also communicate with other networks, such as the public switched telephone network or the Internet 112, or utilize services provided by them. The communication network can also support the use of cloud services, for example, at least a portion of the core network operations can be performed as a cloud service (this is in the Figure 1 114). The communication system may also include a central control entity, or similar entity, providing facilities for networks of different operators to collaborate, for example in spectrum sharing.

[0031] Edge cloud can be brought into the Radio Access Network (RAN) by leveraging Network Function Virtualization (NVF) and Software Defined Networking (SDN). Using edge cloud can mean performing access node operations at least partially in a server, host or node that is operably coupled to a remote radio head or base station including the radio part. It is also possible that the node operations are distributed among multiple servers, nodes or hosts. The application of cloud RAN architecture enables the execution of RAN real-time functions on the RAN side (in the distributed unit DU 104) and the execution of non-real-time functions in a centralized manner (in the centralized unit CU 108).

[0032] 5G can also make use of satellite communications to enhance or supplement the coverage of 5G services, for example by providing backhaul. Possible use cases are to provide service continuity for machine-to-machine (M2M) or Internet of Things (IoT) devices or for passengers in vehicles, or to ensure service availability for critical communications and future railway / maritime / aeronautical communications. Satellite communications can make use of geostationary earth orbit (GEO) satellite systems, but can also make use of low earth orbit (LEO) satellite systems, in particular mega constellations (systems in which hundreds of (nano) satellites are deployed). Each satellite 106 in the constellation can cover several satellite-enabled network entities that create a ground cell. The ground cell can be created by a ground relay node 104 or by a gNB located on the ground or in a satellite.

[0033] The ETSI specifications for transmit (Tx) power and effective isotropic radiated power (EIRP) set for the 60 GHz band (57-71 GHz) (mmWave) are as follows: Tx power is set to 27 dBm and EIRP is set to 40 dBm. Due to the rather limited EIRP, relatively small arrays in terms of the number of antenna elements can be used at network nodes (e.g., gNBs). Small antenna arrays are cost and power efficient. For example, it is assumed that CMOS power amplifier (PA) technology can be used, such as an 8×4 element array, because the required 40 dBm EIRP can be achieved with low power CMOS when the array size (number of antenna elements) is greater than or equal to 32.

[0034] The result of such a small or modest array size in terms of antenna elements is that the antenna radiation pattern (i.e., beam) is relatively wide. In other words, narrow beams or pencil beams may not be used. For example, for a uniform linear array (ULA) with 0.5 lambda element spacing, the 3 dB beamwidth can be approximated by 102° / N, where N is the number of antenna elements in each dimension. Thus, for example, for an 8×4 array, the 3 dB beamwidth is approximately 12.5 degrees in the vertical dimension and 25 degrees in the horizontal dimension, respectively.

[0035] Systems operating in unlicensed bands are typically managed to implement fair spectrum sharing mechanisms, such as Listen Before Talk (LBT). LBT is used as a spectrum sharing mechanism for unlicensed or shared spectrum operations, especially at 7GHz carrier frequency. In unlicensed or shared spectrum operations, network nodes or access nodes (e.g., gNBs) typically operate with sector wide beams (e.g., through 3 sector antennas arranged on a circle, each covering 120 degrees), and user equipment nodes operate with omnidirectional beams. On the other hand, in mmWaves, nodes operate with very narrow beams and LBT type mechanisms may not be needed because the probability of collisions will be very low. Figure 2a By way of example, network nodes (or transmit receive points, TRPs) 210, 212 and user equipment (UE) 220, 222, 224 are shown operating in mmWave with very narrow beams 230, 231, 232, 233, 234, 235.

[0036] However, as described above, due to the relatively low maximum allowed EIRP and due to targeted cost and power efficient transceiver and antenna architectures, in unlicensed operation, such as in 60 GHz unlicensed operation, relatively smaller array sizes will be used in practice. Figure 2b By way of example, the network nodes 210, 212 and the user equipments 220, 222, 224 are shown to operate with beams having moderate beam widths 240, 241, 242, 243, 244, 245. Moderate beam width ratio Figure 2a The narrow beam width shown is wider. It can be observed that the possibility of inter-beam interference or collision will increase. Therefore, the need for fair spectrum sharing channel access mechanism arises.

[0037] It can be assumed that LBT type channel access mechanisms are also adopted for 60GHz mmWave unlicensed operation, at least in scenarios using low maximum allowed EIRP. For example, the European Conference of Postal and Telecommunications Administrations (CEPT) recommendations for Class 1 devices (indoor access) and Class 2 devices (indoor and outdoor access) allow a maximum EIRP of 40dBm and a PSD (power spectral density) of 23dBm / MHz.

[0038] Beam-based operation relies on a beam management (BM) procedure that sets up and maintains one or more beam-pair links between two radio nodes (e.g., a gNB and a UE). A beam-pair link refers to a transmit beam at the transmitter and a receive beam at the receiver of a radio link between two radio nodes (e.g., a gNB and a UE).

[0039] The beam management (BM) procedures developed in Rel-15 and Rel-16 for frequency range 2 (FR2), which is the carrier frequency range between 24 and 52.6 GHz, are believed to provide a good baseline for NR operation above 52.6 GHz, and therefore also for unlicensed operation at 60 GHz. The existing BM procedures, such as P-1, P-2 and P-3, provide a set of functions for, for example, beam searching, beam indication and beam refinement at the gNB and UE. P-1 refers to beam selection, where the gNB scans the beams and the UE selects the best beam and reports it to the gNB. P-2 refers to beam refinement for the transmitter (gNB Tx), where the gNB refines the beam, e.g., scans a narrower beam over a narrower range, and the UE detects the best beam and reports it to the gNB. P-3 refers to beam refinement for the receiver (UE Rx), where the gNB fixes the beam, e.g., repeatedly transmits the same beam, and the UE refines its receiver beam. In FR2, unlike in FR1, the UE and gNB may be able to receive / transmit using only one beam at a given time.

[0040] BM relies heavily on periodic signals, more specifically, on a periodic tracking reference signal (P-TRS) as a quasi-co-located (QCL) source of downlink (DL) signals and channels. In addition, the beam failure detection reference signal (RS) and candidate RS used for new beam identification in the defined beam failure recovery procedure can be periodic, and typically the failure detection RS is a P-TRS, which serves as an effective QCL source for physical downlink control channel (PDCCH) monitoring in the control resource set (CORESET). Based on the QCL source RS, the UE prepares the channel estimation filter and sets its receive (Rx) beam for the upcoming signal. The channel estimation filter may include, for example, time domain and frequency domain estimates, such as delay spread and / or Doppler spread. The same periodic RS can typically be used as a spatial source for uplink signals and channels, i.e., a DL reference signal, based on which the UE can form a transmit beam for uplink (UL) transmission. Figure 3A typical QCL configuration for a target signal (e.g., a downlink signal and a channel) is shown by way of example. The RS (e.g., P-TRS 310) at the beginning of the arrow represents the source. The signal at the end of the arrow, such as a channel state information reference signal (CSI-RS) 322, 323, PDCCH 324, and PDSCH 325 represents the target. Aperiodic TRS (A-TRS) 315 can be associated with P-TRS 310 and inherit the QCL assumption from P-TRS. Both P-TRS and A-TRS can be used as the source of target signals 322, 323, 324, and 325. A-TRS can be used to make TRS denser during the time of serving UEs, thereby providing better performance. P-TRS can be configured or needs to be configured so that A-TRS can be triggered. On the other hand, in higher frequencies, if multiple UEs are in connected mode and the A-TRS of each UE is triggered separately, significant overhead may result.

[0041] The considered channel access mechanism, i.e., LBT, may prevent the transmission of P-TRS which is the primary QCL source for different signals and channels. As a result, the UE may not have the latest QCL source for the upcoming signals and / or channels to be received. This may have a negative impact on both DL performance and UL performance.

[0042] A method is provided in which the TRS allocation (eg, P-TRS allocation) for a user equipment can float over time, and the allocation at each time depends on the allocation of TRS configured on the SSB beams in the cell. No time allocation may be provided in the configuration.

[0043] Figure 4 A flow chart of a method 400 for TRS time allocation is shown by way of example. The method 400 may be, for example, Figure 1 The method 400 is performed by a device 100, which may include a user device, such as a mobile communication device, or in a control device configured to control its functions when installed therein. The method 400 includes determining 410 (multiple) synchronization signal blocks that have been sent in a serving cell. The method 400 includes receiving 420 group information of tracking reference signals, the group information including an indication of (multiple) synchronization signal blocks for which tracking reference signals have been configured in the serving cell. The method 400 includes receiving 430 mapping information, the mapping information including an indication of how individual tracking reference signals are mapped to a time slot structure. The method 400 includes determining 440 the time domain position (multiple) of the device's (multiple) tracking reference signals based on the group information and the mapping information.

[0044] The UE determines the (multiple) synchronization signal blocks (SSBs) transmitted in the serving cell. For example, the determination may be performed based on the remaining minimum system information (RMSI) or based on an indication received from the serving cell. The indication may be received via dedicated high-layer signaling (e.g., gNB signaling), and the UE may read information about the SSBs actually transmitted in the cell from the signaling (ssb-PositionsInBurst). Alternatively, the UE may determine the SSBs actually transmitted in the serving cell by reading common high-layer signaling such as RMSI.

[0045] The UE receives group information from a network node (e.g., a serving cell). The group information includes an indication of the synchronization signal blocks (SSBs) for which a tracking reference signal (TRS) has been configured in the serving cell. The indication of the SSBs may be a subset of the actual transmitted SSBs for which TRS has been configured in the cell. In other words, the group information tells the UE: for which SSBs TRS has been configured. Figure 5 The group information of the tracking reference signal configured in the serving cell is shown by way of example. The SSB 510 may be assigned an operating logical index of 0, 1, 2, 3, 4, 5, 6, 7. The bottom row 505 shows the SSBs for which TRSs have been configured, which are shown as blocks with padding 520, 521, 522, 523, 534. The UE may determine based on the group information: on which SSBs among the actually transmitted SSBs the gNB transmits TRSs in the cell. The UE may transform 530 the SSB index (e.g., 0, 1, 4, 5, 6) with the transmitted TRS to a logical index of 0, 1, 2, 3, 4. The UE may be considered to be "under" SSB #5 523 corresponding to logical index 3. The SSB index in which the UE's TRS is configured may be described, for example, by taking the SSB index as the QCL source of the TRS.

[0046] The UE receives mapping information from a network node (e.g., a serving cell). The mapping information includes an indication of how individual TRSs are mapped to the time slot structure. In other words, the mapping information indicates to the UE how individual TRSs corresponding to a specific logical index are mapped to the time slot structure. The mapping information may also indicate how individual TRSs are mapped to the scan / burst structure. The mapping information or predetermined mapping rules may include indications of, for example, one or more of the following:

[0047] – The starting time slot of the TRS mapping within the radio frame (time slot offset);

[0048] - External periodicity, for example in a radio frame: the number of TRSs in a time slot, or the number of scans in a period; additionally, the TRS may be configured with an external periodicity in a time slot and a reference time slot subcarrier spacing (SCS).

[0049] – Mapping mode, i.e., whether the TRS is mapped to continuous time slots or non-continuous time slots, such as every second time slot, every third time slot, every fourth time slot, etc.;

[0050] – the inner cycle, i.e. the number of mappings in the outer cycle;

[0051] – Information about which SSB is the QCL source for the TRS.

[0052] Figure 6 The mapping information of the indicated TRS based on the group information is shown by way of example. An orthogonal frequency division multiplexing (OFDM) symbol 605 is shown in the bottom row. The logical index can be converted to the TRS position, for example, maintaining a structure of 2 symbols with a difference of 4 symbols, which is a mapping mode known from Rel-15. Figure 6 In the example of , a TRS for 5 SSBs is shown. The slot offset can be defined 610, for example, by mod(SFN, outer period), where SFN is the system frame number and the period in this example is 2, i.e., the configurable number of times in a period is 2. In this example, the duration of the period 620 is 20 ms.

[0053] The UE determines the time domain position of its own (multiple) TRS based on the group information and mapping information. The calculation of the time domain position of the TRS can be based on, for example, the logical SSB index, the time slot offset, the number of scans in the time period, and / or the TRS mapping mode. The determination of the time domain position of the TRS with different configurations is described below.

[0054] Figure 7 By way of example, the mapping of the tracking reference signal onto the time slot structure 700 is shown when no explicit gaps are required between the transmissions of different beams. For example, the configuration of the TRS may indicate an omni-beam LBT without requiring an explicit beam switching gap between the transmissions of different beams. Let us consider that there are 6 TRSs in one time slot.

[0055] The UE may calculate the first timing or first time domain position of the TRS of interest:

[0056] Slot: = slot_offset, starting from the starting time slot, defined by mod(SFN, periodicity) = 0 + floor(NthSSB of TRS / 6), where mod is the modulo operation, SFN is the system frame number, periodicity is the external period, and N is the SSB index of the TRS configured for the UE.

[0057] Symbol: =0 and 4 for mod(Nth SSB of TRS / 6) = 0

[0058] Symbol: =1 and 5 for mod(Nth SSB of TRS / 6) = 0

[0059] Symbol: =2 and 6 for mod(Nth SSB of TRS / 6) = 0

[0060] Symbol: =3 and 7 for mod(Nth SSB of TRS / 6) = 0

[0061] Symbol: =8 and 12 for mod(Nth SSB of TRS / 6) = 0

[0062] Symbol: =9 and 13 for mod(Nth SSB of TRS / 6) = 0

[0063] The UE may calculate the Xth opportunity or the Xth time domain position of the TRS if the Xth opportunity is configured as:

[0064] Slot: = slot_offset, starting from the starting time slot, defined by mod(SFN, periodicity) + floor(Nth SSBof TRS / 6) + slot_offset_Xth_occ

[0065] Symbol: =0 and 4 for mod(Nth SSB of TRS / 6) = 0

[0066] Symbol: =1 and 5 for mod(Nth SSB of TRS / 6) = 0

[0067] Symbol: =2 and 6 for mod(Nth SSB of TRS / 6) = 0

[0068] Symbol: =3 and 7 for mod(Nth SSB of TRS / 6) = 0

[0069] Symbol: =8 and 12 for mod(Nth SSB of TRS / 6) = 0

[0070] Symbol: =9 and 13 for mod(Nth SSB of TRS / 6) = 0

[0071] Figure 7The mapping of the first time slot (14 symbols) in a period to different beams represented by different numbers is shown. In this example, one TRS resource comprises two symbols that differ from each other by four symbols in the time domain. Symbol 705 is shown in the bottom row.

[0072] Figure 8 By way of example, the mapping of TRSs onto the slot structure 800 is shown when one symbol gap is required between transmissions of different beams. For example, the configuration of the TRSs may indicate directional LBT and the need for explicit beam switching gaps between transmissions of different beams. It may be assumed that there is space for three TRSs in one slot.

[0073] The UE may calculate the first timing or first time domain position of the TRS of interest:

[0074] Slot: = slot_offset, starting from the starting time slot, defined by mod(SFN, periodicity) = 0 + floor(NthSSB of TRS / 3), where mod is the modulo operation, SFN is the system frame number, periodicity is the external period, and N is the SSB index of the TRS configured for the UE.

[0075] Symbol: =1 and 5 for mod(Nth SSB of TRS / 3) = 0

[0076] Symbol: =3 and 7 for mod(Nth SSB of TRS / 3) = 0

[0077] Symbol: =9 and 13 for mod(Nth SSB of TRS / 3) = 0

[0078] The UE may calculate the Xth opportunity or the Xth time domain position of the TRS if the Xth opportunity is configured as:

[0079] Slot: = slot_offset, starting from the starting time slot, defined by mod(SFN, periodicity) + floor(Nth SSBof TRS / 3) + slot_offset_Xth_occ

[0080] Symbol: =1 and 5 for mod(Nth SSB of TRS / 3) = 0

[0081] Symbol: =3 and 7 for mod(Nth SSB of TRS / 3) = 0

[0082] Symbol: =9 and 13 for mod(Nth SSB of TRS / 3) = 0

[0083] Figure 8 A mapping of the first time slot (14 symbols) in a time period with different beams represented by different numbers is shown. In this example, one TRS resource includes two symbols that differ from each other by four symbols in the time domain. Since both beam switching and directional LBT are performed before the expected transmission, for example before each expected transmission, a symbol time gap is required. Due to directional LBT, a beam switching gap of one symbol is required. Symbol 805 is shown in the bottom row. For subcarrier spacings where beam switching is no longer feasible within the cyclic prefix of the OFDM symbol, a beam switching gap of one or more OFDM symbols may be required. In some cases, beam switching can be performed within the cyclic prefix of the OFDM symbol, and due to directional LBT, a gap of one or more symbols may be required.

[0084] According to an embodiment, when the UE is in a radio resource control (RRC) connected mode, the UE receives in a paging message an indication of all or actually transmitted SSBs for which TRS has been configured in a serving cell. This allows the network, i.e., a serving cell, such as a gNB, to compactly and flexibly transmit TRS bursts for beams to a UE connected to at least one RRC. The paging message may be sent from the network, for example, on a physical downlink shared channel (PDSCH), on a paging downlink control information (DCI) message, or on a group common physical downlink control channel (GC-PDCCH) DCI message. In addition, a timestamp may be indicated to the UE, where the timestamp indicates when new information and a new TRS scanning structure are applied. In the case of DCI signaling, the DCI payload may be up to 64 bits, which corresponds to the maximum number of SSBs. However, in practice, the DCI payload is equal to the number of SSBs actually transmitted in the serving cell, which the UE may obtain separately from public (e.g., RMSI) or dedicated high-layer signaling.

[0085] The UE may monitor (e.g., periodically) paging, paging DCI, or GC-PDCCH DCI for TRS scan structure updates. The UE may be configured with a specific search space set to obtain monitoring parameters, such as period, offset, number of monitored PDCCH candidates, etc. Additionally, an existing search space set may be used for paging monitoring for TRS scan updates, such as the TYPE-2 common search space provided in PDCCH-ConfigCommon.

[0086] Fig. 9Signaling between a user equipment 910 and a network node 920 (e.g., a gNB) is shown as an example. Time advances from top to bottom. The gNB may indicate 930 the SSB actually sent in the serving cell (i.e., the gNB). The gNB may, for example, send this information periodically. Alternatively, the UE may determine the SSB actually sent based on the RMSI. The gNB may send 935 group information for the TRS. The group information includes an indication of the SSBs for which TRS has been configured in the serving cell. The gNB may determine the logical index of the SSB for which the TRS is to be sent. The group information may be indicated, for example, in a specific paging message (e.g., a DCI message) that the UE occasionally reads or in the PDSCH, and / or via dedicated signaling. In addition, a timestamp may be indicated to the UE, for example, together with the group information. The timestamp indicates when the new information and the new TRS scanning structure are applied. For example, the first updated TRS burst is a TRS burst that exists entirely after the indicated timestamp. Based on the UE's beam report or SSB measurement 940, the gNB can send 945 mapping information, which includes, for example, information about which SSB is the QCL source for the TRS.

[0087] The UE may calculate 950 an index of an SSB for which a TRS is configured. The index may be based on a logical index. The UE may then determine or calculate 955 the time domain location(s) for the TRS based on, for example, the logical SSB index, the slot offset, the number of scans within the time period, and / or the TRS mapping pattern. Additionally, the determination may be based on predefined rule(s) or algorithm(s). The rule(s) or algorithm(s) may be determined by a specification.

[0088] The gNB may prepare the transmission of TRS for a specific SSB in the location according to the logical index and construct (multiple) TRS scans. The gNB may determine a first time location for TRS scanning within the 960 period. The gNB may check the occupancy of radio resources. If it is detected that the radio resources for TRS are occupied, for example, by transmissions from other devices, the gNB will not send TRS. If radio resources are available, the gNB sends TRS via the first time location.

[0089] When the time domain position of the TRS has been determined, the UE attempts 965 to detect the TRS in the determined time domain position. The detection of the TRS can be two-fold. For example, if the UE detects a gNB transmission before determining the position, the UE can determine that a TRS will be sent. Otherwise, the UE attempts to detect (multiple) TRS symbols. If the gNB has detected that there are no radio resources available for TRS, the UE does not detect the TRS transmission.

[0090] Depending on the scenario, i.e., if no resources are available for the first time position, the gNB may determine 970 a second time position for TRS scanning within the time period. If it detects that the radio resources for TRS are not occupied, the gNB will start (multiple) TRS scanning transmissions 975, 976. The TRS scanning transmissions may form a scanning burst. If the TRS is sent via the first time position for TRS scanning within the time period, the gNB may not use the second TRS time position. If the UE has received the TRS via the first time position, it may be assumed that the second time position for TRS scanning within the time period is not used.

[0091] The UE detects 980 or receives the TRS based on the determined allocation, i.e., based on the determined (multiple) time domain positions. The UE can then update, for example, (multiple) receiver channel estimation filters and / or receive beams (Rx beams) based on the detected or received TRS. The detected or received TRS can also help update the time and / or frequency synchronization process at the UE.

[0092] The gNB may detect that the UE needs a QCL source (SSB), for example, based on SSB measurements from the UE. If the new QCL source (i.e., SSB) of a TRS is among the QCL sources of TRSs present in the cell, the gNB may send a Media Access Control-Control Element (MAC-CE) command to update the UE's QCL source. The UE may then determine which TRS to detect, i.e., determine the time domain location of the TRS.

[0093] If the new QCL source is not among the QCL sources for which TRS exists in the cell, the gNB can signal the system frame number (SFN) to the UE when the new TRS scanning structure is used. The gNB can send a MAC-CE command to update the QCL source of the UE. In this case, the gNB can change the QCL source and update the TRS burst by a single MAC-CE. On the other hand, by the proactive behavior of updating the list of SSBs for which TRS is sent, the gN can avoid this situation and avoid additional delays in beam switching of the UE.

[0094] According to an embodiment, the UE may verify a TRS or TRS scan transmission based on the detected (multiple) TRS and the determined (multiple) time domain positions. For example, in the absence of an ongoing downlink transmission from the gNB before the TRS scan structure begins, the UE may use one or more TRS time domain positions to detect and verify whether a TRS scan was sent. The UE may be under two SSB beams configured with TRS, and then the UE may detect and verify the TRS scan transmission using the TRS positions corresponding to the two SSBs. Verification according to this embodiment may be referred to as blind detection.

[0095] According to an embodiment, the UE may verify a TRS or (multiple) TRS scan transmissions as follows: the UE detects that a downlink transmission from the gNB is ongoing, wherein the latter has an indication of the end of a channel occupancy time (COT), wherein the channel occupancy time (COT) either at least partially overlaps with the TRS scan time domain allocation or is later than the end of the TRS scan structure.

[0096] According to an embodiment, the UE may verify the TRS or (multiple) TRS scan transmission based on other known signals transmitted together with the TRS in (multiple) symbols. The transmission of the signal may be based on, for example, frequency division multiplexing or time division multiplexing (FDM / TDM) (back-to-back). Other known signals that may be used as verification signals may be PDCCHs protected by cyclic redundancy check (CRC). For example, the GC-PDCCH carrying information about which SSBs the TRS will be configured for may be used as a verification signal. For this purpose, a special TRS-CORESET may be defined having a TRS search space (SS) having one monitoring opportunity and one PDCCH candidate per SSB in a TRS scan burst. After a valid TRS positioning, a valid UL grant allowing the transmission of PUSCH or PUCCH within the COT acquired by the gNB may also be considered as a verification mechanism for TRS positioning. In some embodiments applicable to the omnidirectional LBT case, the PDCCH scan may be performed before the TRS burst. By detecting the PDCCH within that PDCCH scan, the UE considers the entire TRS burst to be valid.

[0097] Fig.10 Tracking the reference signal with a verification search space 1010 is shown by way of example, which verification search space 1010 can be defined, for example, implicitly within a TRS scan burst. The monitoring position of the transmitted TRS is followed by the corresponding TRS. The UE may monitor through an active transmission configuration indication state (TCI state). The UE can receive the GC-PDCCH in symbol 4 (fifth symbol) 1020 and can determine that i=2. The UE can determine the number of beams (N) transmitted based on the content of the GC-PDCCH. In this example, N is 3. The UE can calculate the starting position of TRS i as symbol exist Fig.10 In the example, the starting position of beam i=2 would be symbol 14 1030, i.e. symbol 0 of the second time slot.

[0098] Authentication of the TRS by the UE may be more efficient than authentication performed by the gNB.

[0099] Fig.11 1 is a flow chart of a method 1100 for TRS time allocation. The method 1100 may be, for example, Figure 1The method 1100 may be performed by a device 104, which may include a network node, such as a gNB, or in a control device configured to control its functions when installed therein. The method 1100 includes sending 1110 group information of tracking reference signals, the group information including an indication of (multiple) synchronization signal blocks for which tracking reference signals have been configured in a serving cell. The method 1100 includes sending 1120 mapping information, the mapping information including an indication of how individual tracking reference signals are mapped to a time slot structure.

[0100] The methods disclosed herein provide robustness for TRS transmissions in beam-based systems using LBT, such as unlicensed NR at 60 GHz. TRS is the primary source of QCL in the system. The methods disclosed herein allow TRS transmissions, such as P-TRS transmissions, to be handled in an efficient manner. The methods disclosed herein allow the UE to autonomously track the correct P-TRS in a scan including beam switching based on the UE's QCL source for the P-TRS.

[0101] Fig.12 An apparatus capable of performing the methods disclosed herein is shown by way of example. A device 1200 is shown, which may include or may be included in, for example, a mobile communication device (such as Figure 1 Mobile 100) or network node (e.g. Figure 1 104). Included in the device 1200 is a processor 1210, which may include, for example, a single-core or multi-core processor, wherein a single-core processor includes one processing core and a multi-core processor includes more than one processing core. The processor 1210 may generally include a control device. The processor 1210 may include more than one processor. The processor 1210 may be a control device. The processing core may include, for example, a Cortex-A8 processing core manufactured by ARM Holdings or a Steamroller processing core designed by Advanced Micro Devices. The processor 1210 may include at least one Qualcomm Snapdragon and / or Intel Atom processor. The processor 1210 may include at least one application-specific integrated circuit ASIC. The processor 1210 may include at least one field programmable gate array FPGA. The processor 1210 may be a component for executing the method steps in the device 1200. The processor 1210 may be configured at least in part by computer instructions to perform actions.

[0102] The processor may include circuitry, or be configured as one or more circuits, configured to perform the stages of the method according to the example embodiments described herein. As used in this application, the term "circuitry" may refer to one or more or all of the following: (a) hardware circuit implementations only (e.g., implementations in analog and / or digital circuits only) and (b) combinations of hardware circuitry and software, such as (as applicable): (i) a combination of analog and / or digital hardware circuitry with software / firmware, and (ii) a hardware processor (including a digital signal processor), software, and any portion of memory with software that work together to enable a device such as a mobile phone to perform various functions) and (c) a hardware circuit and / or processor that requires software (e.g., firmware) to operate, such as a microprocessor or a portion of a microprocessor, but the software may not be present when the software is not required to operate.

[0103] This definition of circuitry applies to all uses of this term in this application, including in any claims. As another example, as used in this application, the term circuitry also covers an implementation of only a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its (or its) accompanying software and / or firmware. The term circuitry also covers (for example and if applicable to a particular claim element) a baseband integrated circuit or processor integrated circuit for a mobile device or a similar integrated circuit in a server, cellular network device or other computing or network device.

[0104] Device 1200 may include memory 1220. Memory 1220 may include random access memory and / or permanent memory. Memory 1220 may include at least one RAM chip. Memory 1220 may include, for example, solid-state, magnetic, optical and / or holographic memory. Memory 1220 may be at least partially accessible by processor 1210. Memory 1220 may be at least partially included in processor 1210. Memory 1220 may be a component for storing information. Memory 1220 may include computer instructions that processor 1210 is configured to execute. When computer instructions configured to cause processor 1210 to perform certain actions are stored in memory 1220, and device 1200 as a whole is configured to run under the instruction of processor 1210 using computer instructions from memory 1220, processor 1210 and / or at least one processing core thereof may be considered to be configured to perform the certain actions. Memory 1220 may be at least partially external to device 1200, but accessible by device 1200.

[0105] The device 1200 may include a transmitter 1230. The device 1200 may include a receiver 1240. The transmitter 1230 and the receiver 1240 may be configured to transmit and receive information, respectively, according to at least one cellular or non-cellular standard. The transmitter 1230 may include more than one transmitter. The receiver 1240 may include more than one receiver. The transmitter 1230 and / or the receiver 1240 may be configured to operate according to, for example, the Global System for Mobile Communications GSM, Wideband Code Division Multiple Access WCDMA, 5G, Long Term Evolution, LTE, IS-95, Wireless Local Area Network, WLAN, Ethernet and / or Worldwide Interoperability for Microwave Access, WiMax standards.

[0106] The device 1200 may include a near field communication NFC transceiver 1250. The NFC transceiver 1250 may support at least one NFC technology, such as NFC, Bluetooth, Wibree, or similar technology.

[0107] The device 1200 may include a user interface UI 1260. The UI 1260 may include at least one of a display, a keyboard, a touch screen, a vibrator arranged to signal the user by vibrating the device 1200, a speaker, and a microphone. The user may be able to operate the device 1200 via the UI 1260, for example to accept an incoming phone call, make a phone call or a video call, browse the Internet, manage digital files stored in the memory 1220 or on the cloud accessible via the transmitter 1230 and the receiver 1240, or via the NFC transceiver 1250, and / or play games.

[0108] The processor 1210 may be provided with a transmitter arranged to output information from the processor 1210 to other devices included in the device 1200 via electrical leads inside the device 1200. Such a transmitter may include a serial bus transmitter, which is arranged to output information to the memory 1220 for storage therein, for example, via at least one electrical lead. As an alternative to the serial bus, the transmitter may include a parallel bus transmitter. Similarly, the processor 1210 may include a receiver, which is arranged to receive information in the processor 1210 from other devices included in the device 1200 via electrical leads inside the device 1200. Such a receiver may include a serial bus receiver, which is arranged to receive information from the receiver 1240, for example, via at least one electrical lead, for processing in the processor 1210. As an alternative to the serial bus, the receiver may include a parallel bus receiver.

[0109] The processor 1210, the memory 1220, the transmitter 1230, the receiver 1240, the NFC transceiver 1250 and / or the UI 1260 may be interconnected in a variety of different ways via electrical leads inside the device 1200. For example, each of the above devices may be individually connected to a main bus inside the device 1200 to allow the devices to exchange information. However, as will be appreciated by those skilled in the art, this is only an example, and various ways may be selected to interconnect at least two of the above devices according to embodiments.

Claims

1. An apparatus for communication, comprising at least one processor and at least one memory including computer program code, wherein the at least one memory and the computer program code are configured to, together with the at least one processor, cause the apparatus to perform: determining one or more synchronization signal blocks that have been sent in the serving cell; receiving group information of a tracking reference signal, the group information comprising an indication of the one or more synchronization signal blocks for which a tracking reference signal has been configured in the serving cell; receiving mapping information including an indication of how individual tracking reference signals are mapped to a time slot structure; as well as Based on the group information and the mapping information, one or more time domain locations of one or more tracking reference signals for the apparatus are determined.

2. The apparatus according to claim 1, further configured to perform: At the determined one or more time domain locations, one or more tracking reference signals are detected.

3. The apparatus of claim 1 , wherein determining one or more synchronization signal blocks transmitted in the serving cell is performed based on: The remaining minimal system information; or An indication is received from the serving cell.

4. The apparatus of claim 1, wherein the group information is received via downlink control information signaling, the downlink control information signaling having a payload equal to the number of one or more synchronization signal blocks actually transmitted in the serving cell.

5. The apparatus according to claim 2, further configured to perform: One or more tracking reference signals are validated based on the detected one or more tracking reference signals and the determined one or more time domain locations.

6. The apparatus according to claim 2, further configured to perform: validating one or more tracking reference signals in response to detecting a downlink transmission from the serving cell with an indication of an end of a channel occupancy time: - at least partially overlaps with the time domain position determined for the tracking reference signal scanning transmission; or – later than the end of the tracking reference signal scanning structure.

7. An apparatus according to any preceding claim, wherein the indication of the determined one or more synchronization signal blocks for which tracking reference signals have been configured in the serving cell comprises a synchronization signal block index.

8. The apparatus according to claim 5, further configured to perform: At least one receiver channel estimation filter and / or receive beam is updated based on the validated one or more tracking reference signals.

9. The apparatus according to claim 1, further configured to perform: The time slot offset is determined based on the modulo operation of the system frame number and the external period.

10. The apparatus according to any one of claims 1 to 6, 8 and 9, further configured to perform: One or more time domain positions are determined based on a modulo operation of a synchronization signal block index in which the tracking reference signal is configured and the number of tracking reference signals in the time slot.

11. A method for communication, comprising: Determining, by the user equipment, one or more synchronization signal blocks that have been sent in the serving cell; receiving, by the user equipment, group information of a tracking reference signal, the group information comprising an indication of the one or more synchronization signal blocks for which a tracking reference signal has been configured in the serving cell; receiving, by the user equipment, mapping information, the mapping information comprising an indication of how individual tracking reference signals are mapped to a time slot structure; as well as The user equipment determines one or more time domain positions of one or more tracking reference signals for the user equipment based on the group information and the mapping information.

12. The method according to claim 11, further comprising: At the determined one or more time domain locations, one or more tracking reference signals are detected.

13. The method of claim 11, wherein determining one or more synchronization signal blocks transmitted in the serving cell is performed based on: The remaining minimal system information; or An indication is received from the serving cell.

14. The method of claim 11, wherein the group information is received via downlink control information signaling, the downlink control information signaling having a payload equal to the number of one or more synchronization signal blocks actually transmitted in the serving cell.

15. The method according to claim 12, further comprising: One or more tracking reference signals are validated based on the detected one or more tracking reference signals and the determined one or more time domain locations.

16. The method according to claim 12, further comprising: validating one or more tracking reference signals in response to detecting a downlink transmission from the serving cell with an indication of an end of a channel occupancy time: - at least partially overlaps with the time domain position determined for the tracking reference signal scanning transmission; or – later than the end of the tracking reference signal scanning structure.

17. A method according to any one of claims 11 to 16, wherein the indication of the determined one or more synchronization signal blocks for which tracking reference signals have been configured in the serving cell comprises a synchronization signal block index.

18. The method according to claim 15, further comprising: At least one receiver channel estimation filter and / or receive beam is updated based on the validated one or more tracking reference signals.

19. The method according to any one of claims 11 to 16 and 18, further comprising: The time slot offset is determined based on the modulo operation of the system frame number and the external period.

20. The method according to any one of claims 11 to 16 and 18, further comprising: One or more time domain positions are determined based on a modulo operation of a synchronization signal block index in which the tracking reference signal is configured and the number of tracking reference signals in the time slot.

21. A non-transitory computer-readable medium comprising program instructions, which, when executed by at least one processor, cause an apparatus to at least perform the method according to at least one of claims 11 to 20.

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