Apparatus, method and computer program

Abstract

A method, an apparatus and a computer program are provided for causing a user equipment to perform transmitting a preamble to an access network node using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting to perform beam refinement on a transmission beam during the random access procedure.

Description

Technical Field

[0001] Examples described herein relate generally to apparatus, methods, and computer programs, and more particularly (but not limited to) to apparatus, methods, and computer programs for apparatus. Background Art

[0002] A communication system may be viewed as a facility that enables communication sessions between two or more entities (such as communication devices, base stations, and / or other nodes) by providing carrier waves between the various entities involved in the communication path.

[0003] The communication system may be a wireless communication system. Examples of wireless systems include public land mobile networks (PLMNs) operating based on radio standards (such as those provided by 3GPP), satellite-based communication systems, and various wireless local area networks, such as wireless local area networks (WLANs). Wireless systems can typically be divided into cells and are therefore often referred to as cellular systems.

[0004] Communication systems and related equipment typically operate according to a given standard or specification, which specifies what the various entities associated with the system are allowed to do and how it should be achieved. It also typically defines the communication protocols and / or parameters used for the connection. An example of a standard is the so-called 5G standard. Summary of the Invention

[0005] According to a first aspect, an apparatus for a user equipment is provided, the apparatus comprising: at least one processor; and at least one memory, the at least one memory comprising software code, which, when executed by the at least one processor, causes the apparatus to perform: sending a preamble to an access network node using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement of a transmission beam during the random access procedure.

[0006] The preamble may indicate that the user equipment is requesting to perform beam refinement on a transmission beam during a random access procedure, and the apparatus may be caused to perform: receiving at least one reference signal from an access network node during the random access procedure; scanning the at least one reference signal to determine a transmission beam narrower than a wide beam; and sending signaling using the narrower transmission beam during the random access procedure.

[0007] Signaling using the narrower transmission beam may include physical uplink shared channel signaling.

[0008] The apparatus may be caused to perform: receiving, from an access network node, an indication of resources to be used for sending at least one reference signal; and using the indication of resources to locate the at least one reference signal.

[0009] The indication of the resources may be received in response to the transmission of the preamble.

[0010] The at least one reference signal may include: at least one tracking reference signal.

[0011] The preamble may indicate that the user equipment is requesting to perform beam refinement on the transmission beam during a random access procedure, and the apparatus may be caused to perform: prior to sending the preamble, determining that the user equipment is in a low power state or does not have sufficient power to send all signaling for completing the random access procedure using a wide beam, wherein the preamble is sent in response to the determination.

[0012] According to a second aspect, there is provided an apparatus for an access node, the apparatus comprising: at least one processor; and at least one memory, the at least one memory comprising software code, which, when executed by the at least one processor, causes the apparatus to perform: receiving a preamble from a user equipment using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement of a transmission beam during the random access procedure.

[0013] The preamble may indicate that the user equipment is requesting to perform beam refinement on a transmission beam during a random access procedure, and the apparatus may be caused to perform: signaling at least one reference signal to the user equipment during the random access procedure; and receiving signaling from the user equipment during the random access procedure using a transmission beam narrower than a wide beam.

[0014] Signaling using the narrower transmission beam may include physical uplink shared channel signaling.

[0015] The apparatus may be caused to perform: signaling to a user equipment an indication of resources to be used for sending at least one reference signal.

[0016] An indication of the resources may be signaled in response to receipt of the preamble.

[0017] The at least one reference signal may include: at least one tracking reference signal.

[0018] According to a third aspect, there is provided an apparatus for a user equipment, the apparatus comprising means for sending a preamble to an access network node using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement on a transmission beam during the random access procedure.

[0019] The preamble may indicate that the user equipment is requesting to perform beam refinement on a transmission beam during a random access procedure, and the apparatus may include components for: receiving at least one reference signal from an access network node during the random access procedure; scanning the at least one reference signal to determine a transmission beam narrower than a wide beam; and sending signaling using the narrower transmission beam during the random access procedure.

[0020] Signaling using the narrower transmission beam may include physical uplink shared channel signaling.

[0021] The apparatus may include means for receiving, from an access network node, an indication of resources to be used for transmitting at least one reference signal; and using the indication of resources to position the at least one reference signal.

[0022] The indication of the resources may be received in response to the transmission of the preamble.

[0023] The at least one reference signal may include: at least one tracking reference signal.

[0024] The preamble may indicate that the user equipment is requesting to perform beam refinement on the transmission beam during a random access procedure, and the apparatus may include means for performing the following: prior to sending the preamble, determining that the user equipment is in a low power state or does not have sufficient power to send all signaling for completing the random access procedure using a wide beam, wherein the preamble is sent in response to the determination.

[0025] According to a fourth aspect, there is provided an apparatus for an access node, the apparatus comprising means for receiving a preamble from a user equipment using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement on a transmission beam during the random access procedure.

[0026] The preamble may indicate that the user equipment is requesting to perform beam refinement on a transmission beam during a random access procedure, and the apparatus may include components for: signaling at least one reference signal to the user equipment during the random access procedure; and receiving signaling from the user equipment during the random access procedure using a transmission beam narrower than a wide beam.

[0027] Signaling using the narrower transmission beam may include physical uplink shared channel signaling.

[0028] The apparatus may include means for signaling to a user equipment an indication of resources to be used for sending at least one reference signal.

[0029] An indication of the resources may be signaled in response to receipt of the preamble.

[0030] The at least one reference signal may include: at least one tracking reference signal.

[0031] According to a fifth aspect, a method for a user equipment is provided, and the method comprises sending a preamble to an access network node using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement on a transmission beam during the random access procedure.

[0032] The preamble may indicate that the user equipment is requesting to perform beam refinement on a transmission beam during a random access procedure, and the method may include: receiving at least one reference signal from an access network node during the random access procedure; scanning the at least one reference signal to determine a transmission beam narrower than a wide beam; and sending signaling using the narrower transmission beam during the random access procedure.

[0033] Signaling using the narrower transmission beam may include physical uplink shared channel signaling.

[0034] The method may include receiving, from an access network node, an indication of resources to be used for sending at least one reference signal; and using the indication of resources to locate the at least one reference signal.

[0035] The indication of the resources may be received in response to the transmission of the preamble.

[0036] The at least one reference signal may include: at least one tracking reference signal.

[0037] The preamble may indicate that the user equipment is requesting to perform beam refinement on a transmission beam during a random access procedure, and the method may include: before sending the preamble, determining that the user equipment is in a low power state or does not have sufficient power to send all signaling for completing the random access procedure using a wide beam, wherein the preamble is sent in response to the determination.

[0038] According to a sixth aspect, a method for an access node is provided and comprises receiving a preamble from a user equipment using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement on a transmission beam during the random access procedure.

[0039] The preamble may indicate that the user equipment is requesting to perform beam refinement on a transmission beam during a random access procedure, and the method may include: signaling at least one reference signal to the user equipment during the random access procedure; and receiving signaling from the user equipment using a transmission beam narrower than a wide beam during the random access procedure.

[0040] Signaling using the narrower transmission beam may include physical uplink shared channel signaling.

[0041] The method may comprise signalling to a user equipment an indication of resources to be used for sending at least one reference signal.

[0042] An indication of the resources may be signaled in response to receipt of the preamble.

[0043] The at least one reference signal may include: at least one tracking reference signal.

[0044] According to a seventh aspect, there is provided an apparatus for a user equipment, comprising: a transmitting circuit system for sending a preamble code to an access network node using a wide beam transmission during a random access procedure, the preamble code indicating whether the user equipment is requesting to perform beam refinement on the transmission beam during the random access procedure.

[0045] The preamble may indicate that the user equipment is requesting to perform beam refinement on a transmission beam during a random access procedure, and the apparatus may include: a receiving circuit system for receiving at least one reference signal from an access network node during the random access procedure; a scanning circuit system for scanning the at least one reference signal to determine a transmission beam narrower than a wide beam; and a transmitting circuit system for sending signaling using the narrower transmission beam during the random access procedure.

[0046] Signaling using the narrower transmission beam may include physical uplink shared channel signaling.

[0047] The apparatus may include receiving circuitry for receiving, from an access network node, an indication of resources to be used for transmitting at least one reference signal, and using circuitry for using the indication of resources to locate the at least one reference signal.

[0048] The indication of the resources may be received in response to the transmission of the preamble.

[0049] The at least one reference signal may include: at least one tracking reference signal.

[0050] The preamble may indicate that the user equipment is requesting to perform beam refinement on the transmission beam during a random access procedure, and the apparatus may include: a determination circuit system for determining, before sending the preamble, that the user equipment is in a low power state or does not have sufficient power to send all signaling for completing the random access procedure using a wide beam, wherein the preamble is sent in response to the determination.

[0051] According to an eighth aspect, there is provided an apparatus for an access node, the apparatus comprising: a receiving circuit system for receiving a preamble from a user equipment using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement of a transmission beam during the random access procedure.

[0052] The preamble may indicate that the user equipment is requesting to perform beam refinement on a transmission beam during a random access procedure, and the apparatus may include: a signaling circuit system for signaling at least one reference signal to the user equipment during the random access procedure; and a receiving circuit system for receiving signaling from the user equipment during the random access procedure using a transmission beam narrower than a wide beam.

[0053] Signaling using the narrower transmission beam may include physical uplink shared channel signaling.

[0054] The apparatus may include signaling circuitry for signaling to a user equipment an indication of resources to be used for sending at least one reference signal.

[0055] An indication of the resources may be signaled in response to receipt of the preamble.

[0056] The at least one reference signal may include: at least one tracking reference signal.

[0057] According to a ninth aspect, a non-transitory computer-readable medium is provided, comprising program instructions for causing an apparatus for a user equipment to perform the following: sending a preamble to an access network node using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement of a transmission beam during the random access procedure.

[0058] The preamble may indicate that the user equipment is requesting to perform beam refinement on a transmission beam during a random access procedure, and the apparatus may be caused to perform: receiving at least one reference signal from an access network node during the random access procedure; scanning the at least one reference signal to determine a transmission beam narrower than a wide beam; and sending signaling using the narrower transmission beam during the random access procedure.

[0059] Signaling using the narrower transmission beam may include physical uplink shared channel signaling.

[0060] The apparatus may be caused to perform: receiving, from an access network node, an indication of resources to be used for sending at least one reference signal; and using the indication of resources to locate the at least one reference signal.

[0061] The indication of the resources may be received in response to the transmission of the preamble.

[0062] The at least one reference signal may include: at least one tracking reference signal.

[0063] The preamble may indicate that the user equipment is requesting to perform beam refinement on the transmission beam during a random access procedure, and the apparatus may be caused to perform: prior to sending the preamble, determining that the user equipment is in a low power state or does not have sufficient power to send all signaling for completing the random access procedure using a wide beam, wherein the preamble is sent in response to the determination.

[0064] According to a tenth aspect, a non-transitory computer-readable medium is provided, comprising program instructions for causing an apparatus for an access node to perform the following: receiving a preamble from a user equipment using a wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement of a transmission beam during the random access procedure.

[0065] The preamble may indicate that the user equipment is requesting to perform beam refinement on a transmission beam during a random access procedure, and the apparatus may be caused to perform: signaling at least one reference signal to the user equipment during the random access procedure; and receiving signaling from the user equipment during the random access procedure using a transmission beam narrower than a wide beam.

[0066] Signaling using the narrower transmission beam may include physical uplink shared channel signaling.

[0067] The apparatus may be caused to perform: signaling to a user equipment an indication of resources to be used for sending at least one reference signal.

[0068] An indication of the resources may be signaled in response to receipt of the preamble.

[0069] The at least one reference signal may include: at least one tracking reference signal.

[0070] According to an eleventh aspect, there is provided a computer program product (eg, software code) stored on a medium, which can cause an apparatus to perform any of the methods described herein.

[0071] According to a twelfth aspect, there is provided an electronic device, which may comprise an apparatus as described herein.

[0072] According to a thirteenth aspect, there is provided a chipset, which may comprise an apparatus as described herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0073] Some examples will now be described, by way of illustration only, with reference to the accompanying drawings, in which:

[0074] Figure 1 shows a schematic diagram of a 5G system;

[0075] Figure 2shows a schematic diagram of a network device;

[0076] Figure 3 A schematic diagram of a user equipment is shown;

[0077] Figures 4A to 4B The beam shape is illustrated;

[0078] Figures 5A to 5C illustrates the beam shape used relative to the antenna array;

[0079] Figure 6 The signal diagram is illustrated;

[0080] Figure 7 illustrates example elements of a RACH configuration element;

[0081] Figures 8 and 9 Example signaling is illustrated;

[0082] Figure 10 illustrates example operations that may be performed by the apparatus described herein; and

[0083] Figures 11 to 12 The diagram illustrates operations that may be performed by the apparatus described herein. DETAILED DESCRIPTION

[0084] The following describes operations that can be performed to improve the efficiency of the random access procedure. Specifically, the following aims to provide a mechanism by which a user equipment (UE) can refine its transmission beam from a wide beam to a narrow beam during the random access procedure. This can help the user equipment save energy because a narrower beam can be associated with lower transmission power than a wider beam.

[0085] In the following description of examples, certain aspects are explained with reference to devices that are generally capable of communicating via wireless cellular systems and mobile communication systems that serve such mobile communication devices. For the sake of brevity and clarity, such aspects are described below with reference to 5G wireless communication systems. However, it should be understood that such aspects are not limited to 5G wireless communication systems and, for example, may be applied to other wireless communication systems (e.g., current 6G proposals, IEEE 802.11, etc.).

[0086] The 3GPP-defined Random Access Channel (RACH) procedure can be used in various situations, including (at least): initial access, small data transmission in RRC inactive mode, and transition from RRC inactive mode to RRC connected mode, as well as beam failure recovery, connection re-establishment, handover, and cell addition.

[0087] The four-step RACH process is as follows Figure 6 shown.

[0088] Figure 6 The signaling performed between the UE 601 and the access network node 602 is illustrated.

[0089] During 6001, UE 601 signals to access network node 602. The signaling (referred to herein as "msg1") may include a random access preamble carried using a physical random access channel (PRACH). The preamble may be selected based on information included in at least one of the SIBs signaled in the SSB(s).

[0090] During 6002, access network node 602 signals UE 601. This signaling (referred to herein as "msg2") may include a random access response (RAR) to the preamble of 6001. The RAR may include an uplink assignment indicating when the signaling of 6003 may be sent. The RAR may be used by the UE to confirm that the UE may proceed with the random access procedure. For example, the RAR may include an identifier of the preamble included in msg1. The RAR may include a temporary identifier of the UE (e.g., a cell radio network temporary identifier), which may be used to identify the UE during 6002 to 6004.

[0091] During 6003, UE 601 signals access network node 602. This signaling (labeled herein as "msg3") may include an identifier that may be used for contention resolution (this may be useful when multiple UEs attempt to register simultaneously, as there are a limited number of preambles available for transmission in msg1).

[0092] During 6004, the access network node 602 signals to the UE 601. This signaling (MSG4) may include contention resolution signaling.

[0093] For the random access procedure, as part of or during the transmission of msg1, the UE uses certain parameters to determine the target power for transmitting msg1. 3GPP specification TS 38.213 provides a formula for performing PRACH power control calculations. Specifically, the formula defines that the RACH transmission power is the minimum of: Pcmax (which is the configured maximum output power of the UE at the transmission frequency) and / or the sum of PRACH Target + PL (which is the sum of the PRACH target received power at the transmission frequency and the path loss at the transmission frequency).

[0094] Additional parameters are used to gradually increase the power used to transmit msg1. These parameters include the time (in number of slots) to wait for a random access response from the network (ra-ResponseWindow), the maximum number of retransmissions (preambleTransMax), the power ramping step size for PRACH (powerRampingStep), and the target power level at the network receiver side (preambleReceivedTargetPower). These parameters are included in the RACH configuration information element, such as Figure 7 These parameters may be provided to the UE in a RACH configuration RRC message, such as described in 3GPP TS 38.331.

[0095] After sending msg1, the UE waits for a response from the network. If no feedback (e.g., msg2) is received within the ra-Responsewindow, a second version of msg1 is sent using a higher transmission power. This higher transmission power is calculated using a preset calculation. This process continues (e.g., sending msg1 at increasingly higher transmission powers when no feedback is received within the time window) until the UE receives a response from the network or the maximum number of transmissions for msg1 is exhausted.

[0096] When the maximum number of transmissions is exhausted without the UE receiving a response from the network, it declares random access failure.

[0097] After receiving the RAR from the network in msg2, the UE sends MSG3 using the uplink grant scheduled in msg2. The uplink grant of the RAR includes the frequency domain and time resource allocation for the UE to send msg3.

[0098] PRACH is used to carry the random access preamble from the UE to the access network node (i.e., 5G NR base station). PRACH helps the access network node adjust the UE's uplink timing.

[0099] 3GPP defines multiple physical RACH (PRACH) preamble formats, each with one or more PRACH orthogonal frequency division multiplexing (OFDM) symbols, a different cyclic prefix, and a different guard time. The PRACH preamble configuration to be used is provided to the UE in system information (e.g., in SIB1).

[0100] The 5G NR random access preamble supports two different sequence lengths and various format configurations: long and short. These different formats facilitate a wide range of deployment scenarios. This is explained below with reference to FR1 and FR2.

[0101] The frequency bands of 5G NR are divided into two different frequency ranges: Frequency Range 1 (FR1) and Frequency Range 2 (FR2).

[0102] FR1 includes frequency bands below 6 GHz, some of which are bands traditionally used by previous standards, but have been expanded to cover potential new spectrum production from 410 MHz to 7125 MHz.

[0103] FR2 includes the frequency band from 24.25 GHz to 52.6 GHz. Compared with the frequency band in FR1, the frequency band in this millimeter wave range has a shorter range but a higher available bandwidth.

[0104] Long sequences use four preamble formats, such as LTE. These formats are designed for large-scale cell deployments in FR1 (below 6 GHz). They use a subcarrier spacing of 1.25 kHz or 5 kHz.

[0105] The short sequence uses nine preamble formats. These formats are designed for small cell deployments, including indoor coverage. These preamble formats are used in both FR1 (sub-6 GHz) and FR2 (millimeter wave) ranges. In FR1, they support 15 or 30 kHz subcarrier spacing, while in FR2, they support 60 or 120 kHz subcarrier spacing.

[0106] The msg2 (RAR) of the random access procedure carries an uplink grant. As mentioned above, this uplink grant indicates to the UE which frequency and time the UE is allowed to send msg3. As defined in 3GPP TS 38.213 Section 8.3, this uplink grant depends largely on the k_2 value and the subcarrier spacing.

[0107] With reference to the time slot of the PUSCH transmission scheduled by the RAR UL grant, if the UE receives a PDSCH from the UE with a random access response message ending in the time slot of the corresponding PRACH transmission, the UE sends the PUSCH in the following time slot: n+k_2+Δ+2μ·Kcell,offset, where k_2 and Δ are provided in 3GPP TS 38.214 and are provided by CellSpecific_Koffset.

[0108] As defined in 3GPP, currently, if the default time domain resource allocation A with normal cyclic prefix (CP) of PUSCH mapping type A is assumed, the UE can be scheduled at most 12 slots later. If pusch-TimeDomainAllocationList is provided in pusch-ConfigCommon, the UE can be scheduled to send Msg3 at most 38 slots later.

[0109] Before describing the example in detail, refer to Figures 1 to 3 Briefly explain some general principles of 5G wireless communication systems.

[0110] Figure 1 A schematic diagram of a 5G system (5GS) 100 is shown. The 5GS may include a user equipment (UE) 102 (which may also be referred to as a communication device or terminal), a 5G access network (AN) (which may be a 5G radio access network (RAN) or any other type of 5GAN, such as a non-3GPP interworking function (N3IWF) / trusted non-3GPP gateway function (TNGF) for non-trusted / trusted non-3GPP access, or a wired access gateway function (W-AGF) for wired access) 104, a 5G core (5GC) 106, one or more application functions (AFs) 108, and one or more data networks (DNs) 110.

[0111] Figure 2 An example of a control device for a communications system is shown, for example, coupled to and / or used to control a station of the access system, such as a RAN node, e.g., a base station, gNB, a central unit of a cloud architecture, or a node of a core network, such as an MME or S-GW, a scheduling entity, such as a spectrum management entity, or a server or host, such as a device hosting an NRF, NWDAF, AMF, SMF, UDM / UDR, etc. The control device may be integrated with a node or module of the core network or RAN, or located externally thereto. In some examples, the base station includes a separate control device unit or module. In other examples, the control device may be another network element, such as a radio network controller or spectrum controller. The control device 200 may be arranged to provide control of communications within the service area of ​​the system. The device 200 includes at least one memory 201, at least one data processing unit 202, 203, and an input / output interface 204. Via this interface, the control device may be coupled to a receiver and transmitter of the device. The receiver and / or transmitter may be implemented as a radio front end or a remote radio head. For example, the control device 200 or the processor 201 may be configured to execute appropriate software code to provide control functionality. References herein to "code" should be understood to refer to software code, and vice versa.

[0112] Now refer to Figure 3 describing in more detail possible wireless communication devices, Figure 3A schematic partial cross-sectional view of a communication device 300 is shown. Such a communication device is generally referred to as a user equipment (UE) or terminal. Suitable mobile communication devices can be provided by any device capable of sending and receiving radio signals. Non-limiting examples include a mobile station (MS) or mobile device, such as a mobile phone or so-called 'smartphone', a computer equipped with a wireless interface card or other wireless interface facility (such as a USB dongle), a personal data assistant (PDA) or tablet computer equipped with wireless communication capabilities, or any combination of these. Mobile communication devices can provide communication, for example, for carrying data such as voice, electronic mail (email), text messaging, multimedia, etc. Thus, users can be provided with and offered a variety of services via their communication devices. Non-limiting examples of these services include two-way or multi-way calls, data communication or multimedia services, or simply access to a data communication network system (such as the Internet). Users can also be provided with broadcast or multicast data. Non-limiting examples of content include downloads, television and radio programs, videos, announcements, various alerts, and other information.

[0113] Wireless communication devices can be, for example, mobile devices (i.e., devices not fixed to a specific location) or fixed devices. Wireless devices may or may not require human interaction to communicate. As used herein, the term "UE" or "user" is used to refer to any type of wireless communication device.

[0114] The wireless device 300 may receive signals over the air or radio interface 307 via suitable means for receiving, and may transmit signals via suitable means for transmitting radio signals. Figure 3 In FIG, the transceiver arrangement is schematically designated by block 306. The transceiver arrangement 306 may be provided, for example, by a radio component and an associated antenna arrangement. The antenna arrangement may be arranged internally or externally to the wireless device.

[0115] A wireless device is typically equipped with at least one data processing entity 301, at least one memory 302, and possibly other components 303 for software and hardware-assisted execution of the tasks it is designed to perform, including controlling access to and communications with access systems and other communication devices. The data processing, storage, and other related control devices may be provided on appropriate circuit boards and / or in a chipset. This feature is denoted by reference numeral 304. The user may control the operation of the wireless device by means of a suitable user interface such as a keypad 305, voice commands, a touch-sensitive screen or touchpad, or a combination thereof. A display 308, a speaker, and a microphone may also be provided. In addition, the wireless communication device may include appropriate connectors (wired or wireless) to other devices and / or for connecting external accessories (e.g., a hands-free device).

[0116] How a UE synchronizes (in both time and frequency) with the access points of the Radio Access Network (RAN) is an important component of any communication network.

[0117] In 5G NR, Synchronization Signal Block (SSB) is one of the features used to synchronize these two entities.

[0118] An SSB is a signal sent by an access network node on a broadcast channel and comprises a combination of a synchronization signal (SS) and a physical broadcast channel (PBCH). An SSB consists of four symbols (e.g., four orthogonal frequency division multiplexing (OFDM) symbols): one symbol for the primary synchronization signal (PSS), one symbol for the secondary synchronization signal (SSS), and two symbols for the PBCH. An SS burst consists of one or more SSBs.

[0119] The SSBs transmitted by an access network node include system information that a receiving UE can use to access the radio access network associated with the access network node. System information is provided in the form of a master information block (MIB) and a number of different system information blocks (SIBs). System information can be divided into minimum system information and other system information.

[0120] The minimum system information includes basic information to be used to enable a UE to initially access a cell, and information used to acquire any other system information.

[0121] Minimum system information may include:

[0122] - MIB, which includes cell barring status information and physical layer information of the cell required to receive additional system information (eg CORESET#0 configuration). The MIB is broadcast periodically on the broadcast channel (BCH).

[0123] -SIB1, which defines the scheduling of other system information blocks and contains information required for initial access. SIB1 is also known as the remaining minimum system information (RMSI) and is broadcast periodically on the downlink shared channel (DL-SCH) and / or sent to the UE in a dedicated manner on the DL-SCH in RRC connected mode.

[0124] In addition to other SIBs, other system information includes SIB17. SIB17 carries the configuration of tracking reference signal (TRS) resources for UEs operating in radio resource control idle and / or inactive mode. SIB17 can be sent within a periodic time window. SIB17 can be sent on a downlink shared channel.

[0125] In more detail, Rel-17 defines a Tracking Reference Signal (TRS) for UEs operating in idle mode. TRS is used for fine synchronization of time, frequency, Doppler, and delay spread information. Synchronization is required for channel estimation and demodulation. TRS is implemented using the Channel State Information Reference Signal (CSI-RS) and was previously available to UEs in RRC connected mode.

[0126] When the UE is in RRC idle or RRC inactive mode, UE energy conservation can be achieved by providing CSI-RS for the connected mode configuration of TRS to track during TRS transmission opportunities. TRS transmitted during TRS opportunities can allow UEs in RRC idle or RRC inactive mode to sleep longer before waking up for the UE's paging opportunity. The TRS opportunity configuration is provided in the SIB (SIB17). The availability of TRS during TRS opportunities is indicated by the Layer 1 availability indication included in SIB17.

[0127] The quasi-collocated (QCL) association of resource sets is given to the synchronization signal block (SSB). The index of the relevant bit is provided for each resource set in the TRS availability indication (indBitID). The validity of such TRS allocation can be configured by the network.

[0128] Information provided in SSBs (eg, in MIBs and SIBs) may be used by a UE to synchronize with a radio access network node during a random access channel (RACH) procedure.

[0129] Beamforming is another concept that is useful when accessing a network via a radio access network.

[0130] Beamforming refers to the ability of a device to transmit and / or receive in a specific direction using an antenna array. Beamforming involves combining the elements in the antenna array so that signals at certain angles experience constructive interference, while signals at other angles experience destructive interference. Beamforming is also known as applying spatial filtering to process signals for directional signal transmission or reception. This improvement over omnidirectional reception / transmission is known as the array's directivity. This increases gain on each side, although link reliability can be affected when the beam is misaligned.

[0131] In mmW (FR2 and beyond), both the access network node and the UE can apply beamforming techniques. Currently, FR2 is deployed with analog beamforming on the UE. This means that a single beam transmission exists while transmitting temporal and spatial filtering for spherical coverage. Typically, the UE beam covers up to 90 degrees in the azimuth plane for each panel, and can be refined to 22 degrees for a 1×4 linear array.

[0132] The front-to-back antenna gain variation on a UE can be as high as 10-15dB, which means that using the correct antenna panel may result in the UE being unable to receive / transmit with the access network node. Figure 4A and Figure 4B shown.

[0133] Figure 4A The figure shows the wide beam antenna pattern on a 1×4 array at the UE. The beam width varies from 90 degrees to 22 degrees, and the front-to-back radio is about 15dB.

[0134] Figure 4B The diagram shows the narrow beam antenna pattern on a 1×4 array at the UE. The beamwidth varies from 90 degrees to 22 degrees, and the front-to-back radio is about 15dB.

[0135] In FR2, the UE uses a beam refinement process to determine how to narrow its transmit beam towards the gNodeB (e.g., how to make a highly directional transmit beam) to increase uplink coverage relative to using a wider transmit beam. Figures 5A to 5C As shown, it illustrates the Figures 5A to 5C UE beam refinement as the number of active antenna elements increases.

[0136] Figure 5A The beam shape 501 obtained when one quarter of the antenna array is used is illustrated.

[0137] Figure 5B The diagram shows a beam shape 501 ′ obtained when half of the antenna array is used. The beam shape 501 ′ is narrower than the beam shape 501 .

[0138] Figure 5C The diagram illustrates a beam shape 501 ″ obtained with full utilization of the antenna array. The beam shape 501 ″ is narrower than the beam shape 501 ′.

[0139] One concept that can be used to facilitate the determination of narrow beams is beam correspondence.

[0140] Beam correspondence refers to the situation where the beam selected for downlink transmission and reception can also be used for uplink transmission and reception. This means that both downlink transmission and uplink transmission will occur on the same beam.

[0141] The beam correspondence requirement can be met by the presence of at least one of a synchronization signal block (SSB) transmission and a channel state indicator reference signal (CSI-RS), assuming that a certain type of quasi-collocation (QCL) is maintained between the SSB and CSI-RS signals.

[0142] A transmit / receive (Tx / Rx) beam correspondence at an access network node is established when at least one of the following conditions is met:

[0143] The access network node can determine the access network node Rx beam to use for uplink reception based on the UE's downlink measurements of one or more Tx beams of the access network node.

[0144] The access network node can determine the access network node Tx beam to use for downlink transmission based on uplink measurements of the access network node on one or more Rx beams of the access network node.

[0145] When the Tx beam of the UE can be verified as corresponding to the downlink beam of the access network node by the UE measuring the downlink reference signal, the Tx / Rx beam correspondence at the UE is established.

[0146] When a UE cannot autonomously meet the beam alignment requirement, it can do so by performing uplink beam scanning and meeting preconfigured UE beam alignment tolerance requirements. During beam scanning, the access network node can measure the uplink sounding reference signals transmitted by the UE to determine the best UE uplink beam and provide information about these measurements to the UE. The UE can use this information to help meet the UE beam alignment requirement.

[0147] In Rel-16, beam correspondence for UEs in connected mode (e.g., UEs in radio resource control (RRC) connected mode) has been studied, and a set of requirements for UEs with and without uplink beam scanning has been derived.

[0148] The corresponding Rel-16 RAN4 3GPP TS 38.101-2 specification for connected mode beams is as follows.

[0149] The beam mapping requirement for power class 3 UEs consists of three components: UE minimum peak EIRP (as defined in 3GPP TS 38.101-2 clause 6.2.1.3), UE spherical coverage (as defined in 3GPP TS 38.101-2 clause 6.2.1.3), and beam mapping tolerance (as defined in 3GPP TS 38.101-2 clause 6.6.4.2).

[0150] EIRP (Effective Isotropic Radiated Power) is the measured power radiated by an antenna in a specific direction. It is also called equivalent isotropic radiated power. EIRP represents the output power of an antenna when it concentrates the signal into a smaller area. EIRP takes into account losses in transmission lines and connectors, as well as antenna gain. It is expressed in dB. To calculate EIRP (Effective Isotropic Radiated Power), input the transmit power, cable loss, and antenna gain.

[0151] When a UE meets one of the following conditions, the beam correspondence requirement is met according to the UE beam correspondence capability information element "beamCorrespondenceWithoutULBeamSweeping" defined in TS 38.306:

[0152] If "beamCorrespondenceWithoutULBeamSweeping" is supported, the UE meets the minimum peak EIRP requirement in Table 6.2.1.3-1 of 3GPP TS 38.101-2 and the spherical coverage requirement in Table 6.2.1.3-3 of 3GPP TS 38.101-2, with autonomously selected UL beams and without uplink beam sweeping. Such a UE is considered to have met the beam correspondence tolerance requirement.

[0153] If "beamCorrespondenceWithoutULBeamSweeping" and

[0154] If "beamCorrespondenceSSB-based-r16" is supported, the side conditions of the enhanced SSB-based beam correspondence requirements defined in clause 6.6.4.3.2 of 3GPP TS 38.101-2 are used and the UE shall meet the minimum peak EIRP requirements in Table 6.2.1.3-1 of 3GPP TS 38.101-2 and the spherical coverage requirements in Table 6.2.1.3-3 of 3GPP TS 38.101-2.

[0155] If "beamCorrespondenceWithoutULBeamSweeping" and

[0156] If "beamCorrespondenceCSI-RS-based-r16" is supported, the side conditions of the enhanced beam correspondence requirements based on CSI-RS defined in clause 6.6.4.3.3 of 3GPP TS 38.101-2 are used, and the UE shall meet the minimum peak EIRP requirements in Table 6.2.1.3-1 and the spherical coverage requirements in Table 6.2.1.3-3 of 3GPP TS 38.101-2.

[0157] If "beamCorrespondenceWithoutULBeamSweeping" is not present, the UE meets the minimum peak EIRP requirements in Table 6.2.1.3-1 of 3GPP TS 38.101-2 and the spherical coverage requirements in Table 6.2.1.3-3 of 3GPP TS 38.101-2 with uplink beam sweeping. Such a UE will meet the beam correspondence tolerance requirements defined in clause 6.6.4.2 and will support uplink beam management as defined in TS 38.306.

[0158] If "beamCorrespondenceWithoutULBeamSweeping" is not present and "beamCorrespondenceSSB-based-r16" is supported, then the UE shall meet the minimum peak EIRP requirement in Table 6.2.1.3-1 of 3GPP TS 38.101-2 and the spherical coverage requirement in Table 6.2.1.3-3 of 3GPP TS 38.101-2 with uplink beam sweeping using the side conditions of the enhanced beam correspondence requirement based on SSB as defined in clause 6.6.4.3.2 of 3GPP TS 38.101-2. Such a UE shall meet the beam correspondence tolerance requirement as defined in clause 6.6.4.2 of 3GPP TS 38.101-2 and shall support uplink beam management as defined in TS 38.306.

[0159] If "beamCorrespondenceWithoutUL-BeamSweeping" is not present and "beamCorrespondenceCSI-RS-based-r16" is supported, the side conditions of the enhanced beam correspondence requirements based on CSIRS defined in clause 6.6.4.3.3 of 3GPP TS 38.101-2 are used and the UE shall meet the minimum peak EIRP requirements in Table 6.2.1.3-1 of 3GPP TS 38.101-2 and Table 6.2.1.3-2 of 3GPP TS 38.101-2.

[0160] The spherical coverage requirements in 6.2.1.3-3 with uplink beam scanning. Such a UE will meet the beam correspondence tolerance requirements defined in 3GPP TS 38.101-2 clause 6.6.4.2 and will support uplink beam management defined in TS 38.306.

[0161] In Rel-18, beam correspondence requirements for UEs currently in radio resource control (RRC) inactive mode and / or RRC idle mode are specified. These requirements involve enhancements to beam correspondence during the initial access state and RRC inactive mode, enhancements to beam correspondence in SSB-based and no uplink beam scanning, and enhancements to beam correspondence for initial access, where beam correspondence verification is based on minimum msg1 spherical coverage. Spherical coverage is an uplink metric that measures how much of a transmit sphere can be received above a power threshold (e.g., x dBm). This uplink metric can be expressed as a percentage. The performance of different UE uplink beams within spherical coverage varies.

[0162] In addition, Rel-18 NR proposes enhancements to FR2, including the goal of defining UE beam mapping requirements for UEs operating in RRC Inactive and Initial Access states.

[0163] These FR2 beam mapping objectives involve: specifying UE beam mapping requirements for initial access and RRC inactive mode, specifying requirements for SSB-based beam mapping without uplink beam scanning, specifying requirements for at least random access small data transmission (SDT) and configuring granted SDT for RRC_INACTIVE to ensure that other transmissions in RRC inactive mode are not excluded, specifying requirements and verification of beam mapping requirements based on at least msg1 spherical coverage for initial access, and studying potential impact on testability aspects (e.g., test time).

[0164] The Rel-18 beam mapping requirements work will focus on ensuring good random access channel (RACH) performance and uplink coverage during RRC idle mode and RRC inactive mode (including SDT) through UE beam mapping requirements. This is intended to provide significant potential for UE energy saving opportunities and provide improvements in latency and signaling overhead reduction.

[0165] A further area of ​​future development involves refining the beam definition, including whether to use a wide beam (also called a "coarse beam") or a narrow beam (also called a "fine beam"). The beam can be considered to include a spatial filter. A wide beam can be formed by activating a single antenna element in an antenna array (e.g., using a single antenna element to transmit a signal). A narrow beam can be formed by activating multiple (e.g., all) antenna elements in an antenna array.

[0166] There are several options.

[0167] For example, as a first option, beam refinement in RRC inactive mode and initial access state can be performed in the same manner as defined for RRC connected mode. For this example, the same SSB configuration as in the current SSB RRC connected case can be used, or a modified version of the SSB configuration can be used.

[0168] The second option can be a combination of the first and second options. In this case, beam refinement can be performed in configuration grant SDT (CG-SDT), but not in random access SDT (RA-SDT) and initial access, or beam refinement can be performed in discontinuous reception, but the efficiency is lower than that of continuous reception.

[0169] As a third option, the coarse beam or fine beam used in initial access depends on the UE implementation and is required to be implementation-independent.

[0170] Currently, only beam correspondence requirements in connected mode are defined in 3GPP. So far, there are no radio access network requirements for beam correspondence for UEs operating in RRC inactive and idle modes.

[0171] 3GPP beam alignment requirements are defined for the 5G NR FR2 band, where beam alignment helps overcome challenging propagation conditions such as high loss. FR2 bands can have large bandwidths to meet use cases requiring higher data rates. UEs can refine their beams to increase antenna gain, thereby achieving peak radiated power in a certain direction.

[0172] However, the beam refinement procedure is currently only specified for use by UEs in RRC connected mode, in which the network may schedule CSI-RS that are repeated 'on', and the UE may use these received reference signals and the beam correspondence principle to refine its transmit beam. The scheduling of CSI-RS that are repeated 'on' may include an aperiodic trigger that indicates to the UE that the CSI-RS uses the same spatial filter (e.g., beam) as used for uplink transmissions. This means that when the UE is operating in RRC connected mode, the UE may use this reference signal for beam refinement. These reference signals are not available for UEs operating in RRC inactive and idle modes. There is no defined procedure that enables the UE to refine its beam when operating in RRC inactive and idle modes.

[0173] about Figure 8 illustrates how beam refinement is performed for connected mode UEs. Figure 8 Signaling between UE 801 and access network node 802 is illustrated.

[0174] 8001 to 8006 relate to the initial access process.

[0175] During 8001, UE 801 determines to signal PRACH on SSB using a wide transmit beam (eg, signal msg1).

[0176] The SSB used for the transmission may be selected using an indication of a RACH opportunity resource indicated in a SIB (eg, in SIB2).A RACH opportunity is a resource specified by a region in the time and frequency domain that may be used for reception of a RACH preamble.

[0177] For example, in NR, synchronization signals (e.g., SSBs) can be associated with corresponding beams, and the UE can select a specific beam for transmitting the RACH preamble. To enable the access network to determine which beam the UE has selected for uplink transmission of the RACH preamble, a mapping is defined between synchronization signals and RACH opportunities. Therefore, by detecting which RACH opportunity the UE transmits the RACH preamble to, the access network node can determine which synchronization signal beam the UE has selected.

[0178] During 8002 , the UE signals msg1 to the access network node 802 using a wide transmission beam.

[0179] During 8003, the access network node 802 signals msg2 to the UE.

[0180] During 8004 , UE 801 determines to signal msg3 to access network node 802 using a wide transmission beam.

[0181] During 8005 , UE 801 signals msg3 to access network node 802 using a wide transmission beam.

[0182] During 8006 , the access network node 802 signals msg4 to the UE 801 .

[0183] During 8007, when the UE is in RRC connected mode, the access network node 802 and the UE 801 are exchanging messages.

[0184] During 8008, the access network node 802 signals to the UE 801. The signaling includes the RRC configuration for the CSI-RS, including the repetition configuration.

[0185] During 8009, the access network node 802 signals to the UE 801. The signaling includes downlink control information activation of the CSI-RS which is repeated as 'on'.

[0186] 8010 relates to UE beam refinement and includes multiple transmissions from the access network node 802 to the UE 801 including CSI-RS that is repeatedly 'on'.

[0187] During 8011, the UE determines that it can use a narrow transmit beam and / or a narrow receive beam.

[0188] During 8012, the access network node 802 signals to the UE 801 on a physical downlink shared channel.

[0189] During 8013 , UE 801 signals access network node 802 on a physical uplink shared channel.

[0190] In addition, the 3GPP standard does not specify the beam type that the UE needs to use for msg1 and msg3 for the four-step RACH procedure. In practice, the UE can be configured to use a wide beam in a cell search scenario to optimize coverage in the angular domain, although this is currently dependent on the UE implementation. This practice may impact the maximum achievable radiated power. There is also the possibility that (multiple) uplink msg1 and / or msg3 transmissions cannot be decoded by the receiving access network node. For example, when the UE does not use the correct transmission beam for the UE's uplink transmission (e.g., the uplink transmission is directed in a different direction from the access network node), the receiving access node may not decode the uplink msg1 and / or msg3 transmission. When uplink msg1 / msg3 is not received due to incorrect directionality of the uplink beam, the transmission power used to send these messages can be increased to alleviate this situation.

[0191] During a random access procedure (which may be performed, for example, during handover), situations may arise where the UE is power-limited, such as at the cell edge. In this case, the UE may have just enough power amplifier power to transmit msg1 using a wide beam including the preamble, but not enough power to successfully transmit msg3 of the 4-step random access procedure (especially when msg3 also includes payload).

[0192] One way the UE can mitigate this and ensure that msg3 reaches the access network node is to increase the transmit antenna gain by further refining the UE's transmit beam to have a very narrow beam. However, when the latest possible uplink grant allocation given in msg2 is only 38 time slots (i.e., 4.75ms in a 120kHz subcarrier spacing, 0.125ms * 38 time slots as described above), it is difficult for the UE to determine its optimal Tx narrow beam during PRACH. Therefore, how the UE can use different transmit beams and / or spatial filters during PRACH has not yet been addressed.

[0193] The present application addresses at least one of these issues by describing a mechanism for allowing a UE operating in any RRC mode (e.g., RRC inactive mode, RRC connected mode, and / or RRC idle mode) to indicate to an access network node that the UE wishes to refine its transmit beam during a RACH procedure.

[0194] For example, the UE may send the following request to the access network node: the access network node may send additional reference signals between the UEs transmitting msg1 and msg3 during the RACH process. The UE may use the received additional reference signals to refine its transmit beam from a wide beam used to transmit msg1 to a narrow beam used to transmit msg3. In other words, in order to enable the UE to refine its Tx beam specifically for msg3, additional reference signals may be provided to the UE between msg1 and msg3. The UE may further scan its receive beam based on these reference signals to derive the UE's preferred (e.g., optimal) transmission narrow beam.

[0195] Dynamic reference signal allocation from the network to the UE (depending on the UE indicating that it wishes to refine its transmission beam from a wide beam to a narrow beam) is also provided, as well as signaling of the reference signal allocation to the UE via msg2. For example, the dynamic signal allocation may include a TRS activation signal to indicate that a TRS transmission is to be sent.

[0196] This and the techniques described below are particularly useful when performed by a power-limited UE (e.g., a UE operating in RRC idle mode, RRC inactive mode, and / or a mode in which its available battery power has fallen below a predetermined threshold). This is because the UE can save energy by transmitting faster than with existing techniques using narrow beam transmissions. In particular, these additional reference signals are most useful for situations where the UE is power-limited in MSG1 using a wide transmission beam, as such a UE would not have sufficient power to successfully transmit MSG3. By signaling a request for additional reference signal transmission to the network, the impact of the UE's low power state can be mitigated.

[0197] While these techniques are particularly useful for power-constrained UEs (and for clarity, the following examples are constructed in this context), it should be understood that the presently described techniques are not limited to these examples, and that similar advantages can be achieved by a UE implementing the presently described techniques when there are no power constraints. For example, a UE in RRC connected mode can implement the presently described techniques and, relative to an RRC connected mode UE that does not implement the presently described techniques, save energy resources.

[0198] The access network node may use TRS for idle / inactive mode UEs to enable the UEs to refine their beams based on UE indications.

[0199] The following proposes the configuration of on-demand TRS (PRACH triggering) in SIB1, which can be performed regardless of whether the UE is in RRC idle mode, RRC inactive mode or RRC connected mode. Certain preambles (e.g., in SIB1) can be reserved and / or allocated for the UE to indicate the need for beam refinement.

[0200] The TRS configuration may be provided in at least one SIB. For example, the TRS configuration may be included in SIB1, SIB17, or both SIB1 and SIB17.

[0201] The TRS configuration may indicate one or more TRS resource sets associated with the same SSB index to provide more resources (eg, more time domain resources) for beam refinement.

[0202] The TRS configuration may be sent in response to receiving a pre-configured RACH preamble associated with scheduling of at least one TRS transmission by the access network node between the transmissions of msg2 and msg3.

[0203] Therefore, the UE may indicate to the access network node during the RACH procedure (eg, by the UE selecting a preamble for msg1) that an additional reference signal is requested to be sent between msg2 and msg3 in order to send msg3 with sufficient radiated power.

[0204] In response to the request, the access network node schedules and sends a TRS before providing an uplink grant for Msg3. The TRS may be scheduled using at least one of the DCI scheduling RARs, or directly scheduled in the RAR of msg2.

[0205] The UE then uses the TRS scheduled between Msg2 and Msg3 to refine its beam.

[0206] Using the current definition in 3GPP TS 38.331, for a UE operating in idle mode with a 10-slot period, the highest configurable TRS allocation is two consecutive slots, with two TRS symbols per slot. Therefore, using the currently described techniques, this equates to a maximum of four opportunities per 1.25ms in FR2 120kHz subcarrier spacing (SCS) for UE beam refinement. Assuming a maximum TRS allocation of 4 OFDM symbols for 10 slots, the UE can try four different receive beams within 1.2ms, and the latest uplink grant timing is 38 slots, which gives the UE 12 opportunities to scan the Rx beam before msg3 is to be transmitted. This means that the UE can even perform receive filtering to improve the accuracy of beam refinement.

[0207] When the TRS configuration is signaled via SIB17, the TRS timing can be configured to the UE in RRC idle or RRC inactive mode via the information element labeled "TRSResourceSetConfig" (in SIB17). A "TRSResourceSetConfig" can contain up to 64 "TRSResourceSets". Each TRSResourceSet configures a set of non-zero power (NZP) CSI-RS resources (2 or 4 resources).

[0208] This process is at least about Figures 9 to 12 shown.

[0209] Figure 9 The diagram illustrates signaling that can be performed between UE 901 and access network node 902. In the following, msg1, msg2, msg3 and msg4 may have the same meaning as in the above reference. Figure 6 For example, msg1 may include a preamble for initiating a random access procedure between a UE and an access network node, msg2 may include a random access response including an uplink grant allocation on which the UE may send msg3, msg3 may include signaling for enabling contention resolution for the UE to access the radio access network, and msg4 may include an acknowledgment of the contention resolution signaling of msg3.

[0210] During 9001 , UE 901 and access network node 902 exchange signaling depending on whether the UE is in idle mode and / or inactive mode.

[0211] During 9002, the access network node 902 broadcasts a synchronization signal burst. The synchronization signal may include at least one SIB. The synchronization signal may include SIB1, which includes a preamble packet for use by the UE to indicate whether beam refinement between msg1 and msg3 is requested. The synchronization signal may include SIB17, which includes the configuration of the TRS (e.g., the period and / or validity of the TRS) for the UE operating in idle mode. When the TRS validity function is not required, the access network node may be able to disable the function.

[0212] 9003 to 9012 relate to the initial access process.

[0213] During 9003, UE 901 determines to use a wide transmission beam for transmitting msg1 and determines that beam refinement is to be requested prior to transmitting msg3. The latter determination may be in response to determining that the UE is in a low-power state. The UE may be in a low-power state when it is in an energy-limited mode (e.g., in RRC idle and / or RRC inactive mode). The UE may be in a low-power state when it determines that the battery power available at the UE is less than a predetermined threshold.

[0214] During 9004, UE 901 signals to access network node 902. The signaling may include msg1. The signaling may include a preamble sent on the PRACH over a synchronization signal block. The signaling may include a dedicated preamble indicating (to the access network node) that a reference signal for beam refinement is requested to be sent between the transmissions of msg1 and msg2.

[0215] During 9005, access network node 902 signals UE 901. The signaling may include msg2. This msg2 may be configured to indicate that a TRS will be triggered for the UE operating in idle mode before the msg uplink grant request is sent. The receipt of msg2 may implicitly indicate that a TRS will be triggered for the UE. msg2 may be configured to include an explicit indication that a TRS will be triggered for the UE. If the UE does not receive msg2, UE 901 may attempt to retransmit msg1 using a higher power than the power used to previously transmit msg1 (e.g., the "step-up" transmission power used to transmit msg1).

[0216] 9006 to 9009 represent a plurality of TRS signals sent by the access network node 902 for reception by the UE 901 .

[0217] During 9010, the UE determines that the UE has sufficiently refined its transmit and / or receive beams so that the UE can use a narrow transmit beam for sending msg3.

[0218] During 9011, UE 901 sends a signal to access network node 902. The signaling may include msg3. The signaling may be sent using a narrow beam. The narrow beam may have been obtained through the refinement of 9006 to 9010.

[0219] During 9012, the access network node 902 signals to the UE 901. The signaling may include msg4.

[0220] During 9013, UE 901 and access network node 902 communicate according to RRC connected mode.

[0221] During 9014, the access network node 902 signals to the UE 901 using a physical downlink shared channel.

[0222] During 9015 , UE 901 signals to access network node 902 using a physical uplink shared channel.

[0223] Figure 9 These operations are about Figure 10 As shown, 1001 to 1002 represent operations to be performed by an access network node, and 1003 to 1015 relate to operations to be performed by a UE.

[0224] During 1001, the access network node broadcasts SIB1. The SIB1 indicates at least one preamble group that is used by the UE to indicate that beam refinement is to be requested during the RACH procedure. For example, a preamble from the first group (Group 1) can be used to indicate that the UE requests TRS transmission for beam refinement, while a preamble from the second group (Group 2) can be used to indicate that the UE does not request TRS transmission for beam refinement.

[0225] Compared to the current 3GPP-defined SIB1, this SIB1 includes a new field in the "RACH-ConfigGeneric" field included in SIB1, labeled "prach-ConfigurationIndex-BR" herein. This "prach-ConfigurationIndex-BR" field will include information about the preamble that the network will use to allow beam refinement between msg1 and msg3. For example, the "prach-ConfigurationIndex-BR" field may include an indication of the preamble(s) of group 1 and / or an indication of the preamble(s) of group 2.

[0226] During 1002, the access network node broadcasts SIB17. The SIB17 includes a TRS configuration for use when the UE operates in RRC idle mode and / or RRC inactive mode.

[0227] During 1003 to 1006, the UE makes a series of determinations.

[0228] During 1003 , the UE receives and decodes MIB, SIB1 and SIB2 or a handover command to calculate the power of PRACH transmission for the random access preamble.

[0229] During 1004, the UE determines whether the UE can transmit with the calculated power and the power available to the UE while using the wide beam.

[0230] When the UE determines during 1004 that the UE can transmit with the calculated power and the power available to the UE while using the wide beam, the UE proceeds to 1005 .

[0231] During 1005, the UE determines whether transmitting at the calculated power and the power available to the UE while using the wide beam would cause the UE to fall below a minimum power threshold.

[0232] When the UE determines during 1005 that transmitting at the calculated power and the power available to the UE while using the wide beam will subject the UE to power limitations, the UE proceeds to 1006 .

[0233] During 1006, the UE determines whether the UE can use an antenna element array to refine its beam. When the frequencies involved are in FR2, the array can be an FR2-based array. However, it should be understood that in other examples, the presently described techniques can be applied to frequencies in a range outside of FR2 (e.g., above FR2).

[0234] When the UE determines during 1006 that the UE can use an FR2-based array to refine its beam, the UE proceeds to 1007 .

[0235] During 1007 , the UE uses a dedicated preamble (eg, from group 1 ) to indicate to the network that the UE requires additional reference signals between msg2 and msg3 in order for the UE to refine its transmit beam.

[0236] The UE receives an indication that activation of the TRS used in idle mode has been enabled during 1008. This indication may be received in, for example, msg2.

[0237] During 1009, the UE scans its receive narrow beam across multiple received TRS signals to infer the "best" transmit beam for sending msg3.

[0238] During 1010 , the UE sends msg3 to the access network node using the narrow transmission beam determined during 1009 .

[0239] During 1011, the UE receives msg4.

[0240] During 1012, the UE is RRC connected.

[0241] When the UE determines during 1004 that the UE cannot transmit with the calculated power and the power available to the UE while using the wide beam, the UE proceeds to 1013 .

[0242] Similarly, when the UE determines during 1006 that the UE cannot refine its beam using the FR2-based array, the UE proceeds to 1013 .

[0243] During 1013 , the UE determines to connect to the access network node using another SSB and / or another Transmission Reception Point (TRP) and enters RRC Connected Mode.

[0244] When the UE determines during 1005 that transmitting with the calculated power and the power available to the UE while using the wide beam does not subject the UE to power limitation, the UE proceeds to 1014 .

[0245] During 1014, the UE determines to use a dedicated preamble (eg, from group 2) to indicate to the network that the UE does not require additional reference signals between msg2 and msg3 in order for the UE to refine its transmit beam.

[0246] During 1015, the UE receives msg2. The msg2 includes an uplink grant with a wide beam. The msg2 does not include an indication that activation of the TRS used in idle mode is enabled.

[0247] During 1016 , the UE sends msg3 to the access network node using the wide beam grant received during 1015 .

[0248] During 1017 , the UE receives msg4 before proceeding to 1012 .

[0249] When realized Figure 9 and Figure 10 When the above functionality is implemented, a UE that determines it is power-limited can request to enable TRS transmission before sending MSG3. This allows the UE to refine its uplink transmission beam by scanning for downlink TRS reception. The access network node determines whether to grant or ignore the UE request based on network implementation. For example, under load or other network conditions where using network resources to transmit additional TRS signals would be unfavorable to the network and other users, the network may ignore the UE instruction.

[0250] It will be appreciated that although the above describes the use of TRSs to provide additional reference signals on which beam refinement is performed, the presently described techniques are not limited thereto.

[0251] Figure 11 and Figure 12 The diagram illustrates some features of the above examples. Therefore, it can be understood that some of the operations mentioned below can find corresponding relationships in the above examples.

[0252] Figure 11 Operations that may be performed by an apparatus for user equipment are illustrated.

[0253] During 1101 , a user equipment transmits a preamble to an access network node using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement on a transmission beam during the random access procedure.

[0254] Beam refinement involves the process of determining a transmission beam that is narrower than the beam previously used for transmission. In other words, beam refinement involves the process of determining a transmission beam that is more directional than the beam previously used for transmission. In the present case, the user equipment requests beam refinement with respect to the beam used to transmit the preamble so that a narrower beam than the preamble transmission beam can be used for another transmission of the RACH procedure (e.g., MSG3).

[0255] The request to perform beam refinement may include a request to send a reference signal to enable the user equipment to perform beam refinement. For example, the request to perform beam refinement may include a request for the access network node to send a TRS between receiving the preamble and receiving msg3.

[0256] The request to perform beam refinement may include a request for the access network node to provide an uplink grant to send msg3 during the latest possible transmission opportunity. This may help maximize the number of opportunities during which the UE may perform the beam refinement mechanism.

[0257] The preamble may indicate that the user equipment is requesting beam refinement of the transmit beam during a random access procedure. The UE may then receive at least one reference signal from an access network node during the random access procedure; scan the at least one reference signal to determine a transmit beam narrower than a wide beam; and send signaling using the narrower transmit beam during the random access procedure. The term "scanning" here refers to the network signaling multiple downlink beams using the same spatial filter, and the UE using multiple (different) refined receive beams to determine which receive beam is receiving the downlink beam with the highest power. This receive beam corresponds to the best aligned receive beam.

[0258] Signaling using the narrower transmission beam may include physical uplink shared channel signaling. In other words, the narrow transmission beam may include msg3.

[0259] The UE may receive, from an access network node, an indication of resources to be used for transmitting at least one reference signal; and use the indication of the resources to locate the at least one reference signal. The indication of the resources may include a SIB. The indication of the resources may include SIB17 (e.g., which defines a TRS). The indication of the resources may include SIB1.

[0260] The indication of the resources may be received in response to the transmission of the preamble. For example, the indication of the resources may be included in the random access response. In other words, the indication of the resources may be included in msg2.

[0261] The at least one reference signal may include: at least one tracking reference signal.

[0262] The preamble may indicate that the user equipment is requesting beam refinement of the transmission beam during the random access procedure. In this case, the UE may determine, before sending the preamble, that the user equipment is in a low power state or does not have sufficient power to transmit all signaling for completing the random access procedure using a wide beam, wherein the preamble is sent in response to this determination. For example, the UE may determine that the UE is in RRC idle mode, RRC inactive mode, and / or has a battery power level below a predetermined threshold.

[0263] Figure 12 The diagram illustrates operations that may be performed by an apparatus for an access node (e.g., a gNB or other radio access network node). The access node may be the one described above with respect to Figure 11 The access node mentioned.

[0264] During 1201, the access node receives a preamble from a user equipment using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement on the transmission beam during the random access procedure. The user equipment may be configured as described above in conjunction with Figure 11 In addition, the above Figure 11 The comments made can also be applied to Figure 12 corresponding features.

[0265] The preamble may indicate that the user equipment is requesting to perform beam refinement on a transmission beam during a random access procedure. The access node may be caused to signal at least one reference signal to the user equipment during the random access procedure; and receive signaling from the user equipment using a transmission beam narrower than a wide beam during the random access procedure.

[0266] The signaling using the narrower transmission beam may include physical uplink shared channel signaling. For example, the signaling using the narrower transmission beam may include msg3.

[0267] The access node may signal to the user equipment an indication of resources to be used for sending the at least one reference signal.

[0268] An indication of the resources may be signaled in response to receipt of the preamble. For example, the indication may be signaled in a random access response. For example, the indication may be included in msg2.

[0269] The at least one reference signal may include: at least one tracking reference signal.

[0270] An advantage of the presently described technique is that the RACH procedure of the present invention is not delayed due to UE beam refinement between msg1 and msg3. It is embedded in the RACH with a dedicated reference signal between Msg2 and Msg3.

[0271] In general, the above describes operations that can be performed to improve the efficiency of the random access procedure. Specifically, the following aims to provide a mechanism by which a user equipment (UE) can refine its transmission beam from a wide beam to a narrow beam during the random access procedure. This can help the user equipment save energy because a narrower beam can be associated with lower transmission power than a wider beam.

[0272] The above mechanism can be applied to any UE that wishes to establish or re-establish synchronization with the network. This may be due to a variety of different reasons.

[0273] For example, the UE may attempt to establish or re-establish synchronization with the network during:

[0274] i) Initial access of UE from RRC idle mode;

[0275] ii)RRC connection reestablishment process;

[0276] iii) switching;

[0277] iv) When the uplink synchronization state is determined to be "out of sync", when the UE is in

[0278] In RRC connected mode, downlink or uplink data arrives;

[0279] v) transition from UE RRC inactive mode;

[0280] vi) used to add time for establishing time alignment for the secondary cell;

[0281] vii) requests for other system information; and

[0282] viii) Beam failure recovery (eg, when the beam is not aligned correctly).

[0283] The foregoing description provides a complete and informative description of some examples by way of non-limiting examples. However, various modifications and adaptations will become apparent to those skilled in the relevant art in view of the foregoing description when read in conjunction with the accompanying drawings and claims. Nevertheless, all such and similar modifications of these teachings will still fall within the scope of the appended claims.

[0284] In the above, different examples are described using radio access architectures based on Long Term Evolution Advanced (LTE-Advanced, LTE-A) or New Radio (NR, 5G) as examples of access architectures to which the described techniques can be applied, however, the examples are not limited to such architectures. By appropriately adjusting parameters and procedures, these examples can also be applied to other types of communication networks with appropriate means. Some examples of other options for suitable systems are Universal Mobile Telecommunications System (UMTS) Radio Access Network (UTRAN), 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.

[0285] As described herein, various aspects are described in the detailed description of the examples and in the claims. Generally, some examples can be implemented in hardware or dedicated circuits, software code, logic, or any combination thereof. For example, some aspects can be implemented in hardware, while other aspects can be implemented in firmware or software code that can be executed by a controller, microprocessor, or other computing device, but the examples are not limited thereto. Although various examples may be illustrated and described as block diagrams, flow charts, or using some other graphical representation, it is well understood that, as non-limiting examples, the blocks, devices, systems, techniques, or methods described herein can be implemented in hardware, software code, firmware code, dedicated circuits or logic, general-purpose hardware or a controller or other computing device, or some combination thereof.

[0286] These examples may be implemented by computer software code stored in a memory and executable by at least one data processor of the entity involved, or by hardware, or by a combination of software code and hardware.

[0287] The memory referred to herein may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory.

[0288] The (data) processor referred to in this document may be of any type suitable to the local technical environment and may include, by way of non-limiting example, one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), an FPGA, a gate-level circuit, and a processor based on a multi-core processor architecture.

[0289] Furthermore, in this regard, it should be noted that any process (e.g. Figure 11 and / or Figure 12 The processes described herein, and / or other processes described previously, may represent the operation of a computer program deployed by at least one processor included in the apparatus (where the computer program includes instructions for causing the apparatus to perform at least one action, the instructions being represented as software code stored on at least one memory), or may represent interconnected logic circuits, blocks, and functions, or may represent a combination of the operation of a computer program deployed by at least one processor included in the apparatus and logic circuits, blocks, and functions. The software code may be stored on a memory, such as a physical medium such as a memory chip or a memory block implemented within a processor, a magnetic medium (such as a hard disk or floppy disk), and an optical medium (such as a DVD and its data variant, a CD, etc.).

[0290] The memory may be of any type suitable for the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory, and removable memory. The data processor may be of any type suitable for the local technical environment and may include, by way of non-limiting example, one or more of a general-purpose computer, a special-purpose computer, a microprocessor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a gate-level circuit, and a processor based on a multi-core processor architecture.

[0291] Alternatively or additionally, some examples may be implemented using circuitry. The circuitry may be configured to perform one or more of the previously described functions and / or method steps. The circuitry may be provided in a base station and / or a communication device and / or a core network entity.

[0292] As used in this application, the term "circuitry" may refer to one or more or all of the following:

[0293] (a) Pure hardware circuit implementation (such as implementation in analog and / or digital circuit systems only)

[0294] now);

[0295] (b) A combination of hardware circuitry and software code, such as:

[0296] (i) a combination of analog and / or digital hardware circuits and software / firmware code, and

[0297] (ii) any portion of hardware processor(s) (including digital signal processor(s)) with software code, software code and memory(s) that work together to cause an apparatus (such as a communication device or base station) to perform the various steps previously described.

[0298] functions; and

[0299] (c) Hardware circuit(s) and / or processor(s), such as microprocessor(s) or part(s) of microprocessor(s), which require software code (e.g.

[0300] Firmware) to operate, but the software code can be absent when not required for operation.

[0301] 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 merely a hardware circuit or processor (or multiple processors) or a portion of a hardware circuit or processor and its (or their) accompanying software and / or firmware code. The term circuitry also covers, for example, an integrated device.

[0302] Implementations of the present disclosure can be implemented in various components such as integrated circuit modules. The design of integrated circuits is generally a highly automated process. Complex and powerful software tools can be used to convert a logic-level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

[0303] As used herein, “at least one of: ” and “at least one of ” and similar expressions (where a list of two or more elements is connected by “and” or “or”) refer to at least any one of these elements, or at least any two or more of these elements, or at least all of these elements.

[0304] The term "non-transitory" as used herein is a restriction to the medium itself (ie, tangible, not a signal), not to the persistence of the data storage (eg, RAM vs. ROM).

[0305] The independent claims define the scope of protection sought by various examples of the present disclosure. Examples and features described in this specification that do not fall within the scope of the independent claims, if any, should be construed as helpful for understanding examples of the present disclosure.

[0306] The above description provides a complete and informative description of example implementations of the present disclosure by way of non-limiting examples. However, various modifications and adaptations will become apparent to those skilled in the relevant art in view of the above description when read in conjunction with the accompanying drawings and the appended claims. Nevertheless, all such and similar modifications of the teachings of the present disclosure will still fall within the scope of the present invention as defined in the appended claims. Indeed, further implementations may include combinations of one or more implementations with any other implementations discussed above.

[0307] Terms

[0308] The various features of the above are described below in the form of clauses.

[0309] According to the first clause, there is provided an apparatus for a user equipment, the apparatus comprising: at least one processor; and at least one memory, the at least one memory comprising software code, which, when executed by the at least one processor, causes the apparatus to perform: sending a preamble to an access network node using wide beam transmission during a random access procedure, the preamble indicating: whether the user equipment is requesting beam refinement of a transmission beam during the random access procedure.

[0310] According to clause 2, there is provided an apparatus according to clause 1, wherein the preamble indicates that: the user equipment is requesting to perform beam refinement on the transmission beam during the random access procedure, and the apparatus is caused to perform: receiving at least one reference signal from the access network node during the random access procedure; scanning the at least one reference signal to determine a transmission beam narrower than the wide beam; and sending signaling using the narrower transmission beam during the random access procedure.

[0311] According to clause 3, there is provided an apparatus according to clause 2, wherein the signaling using the narrower transmission beam comprises: physical uplink shared channel signaling.

[0312] According to clause 4, there is provided an apparatus according to any one of clauses 2 and 3, the apparatus being caused to perform: receiving an indication of resources to be used for sending the at least one reference signal from the access network node; and using the indication of the resources to locate the at least one reference signal.

[0313] According to the fifth clause, which may refer to any preceding clause, the indication of the resource may be received in response to the transmission of the preamble.

[0314] According to clause 6, which may refer to any preceding clause, the at least one reference signal may comprise: at least one tracking reference signal.

[0315] According to clause 7, which may refer to any preceding clause, the preamble indicates that the user equipment is requesting beam refinement to be performed on the transmission beam during the random access procedure, and the apparatus is caused to perform: before sending the preamble, determining that the user equipment is in a low power state or does not have sufficient power to send all signaling for completing the random access procedure using the wide beam, wherein the preamble is sent in response to the determination.

[0316] According to clause 8, there is provided an apparatus for an access node, the apparatus comprising: at least one processor; and at least one memory, the at least one memory comprising software code, which, when executed by the at least one processor, causes the apparatus to perform: receiving a preamble from a user equipment using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement of a transmission beam during the random access procedure.

[0317] According to clause 9, which may refer to clause 8, the preamble indicates that: the user equipment is requesting to perform beam refinement on the transmission beam during the random access procedure, and the device is caused to perform: signaling at least one reference signal to the user equipment during the random access procedure; and receiving signaling from the user equipment using a transmission beam narrower than the wide beam during the random access procedure.

[0318] According to clause 10, it may refer to clause 9, wherein the signaling performed using the narrower transmission beam includes: physical uplink shared channel signaling.

[0319] According to clause 11, which may depend upon any of clauses 9 and 10, the apparatus is caused to perform: signalling to the user equipment an indication of resources to be used for sending the at least one reference signal.

[0320] According to clause 12, which may refer to clause 11, an indication of said resources is signalled in response to said reception of said preamble.

[0321] According to Clause 13, which may refer to any one of Clauses 9 to 12, the at least one reference signal includes: at least one tracking reference signal.

Claims

1. A device for a user equipment, the device comprising: Means for sending a preamble to an access network node using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement of a transmission beam during the random access procedure.

2. The apparatus of claim 1 , wherein the preamble indicates that the user equipment is requesting beam refinement of a transmission beam during the random access procedure, and the apparatus further comprises: means for receiving at least one reference signal from said access network node during said random access procedure; means for scanning said at least one reference signal to determine a transmission beam narrower than said wide beam; as well as means for signaling using the narrower transmit beam during the random access procedure.

3. The apparatus of claim 2 , wherein the signaling using the narrower transmission beam comprises: Physical uplink shared channel signaling.

4. The apparatus according to any one of claims 2 or 3, further comprising means for: Receiving, from the access network node, an indication of resources to be used for sending the at least one reference signal; and using the indication of resources to locate the at least one reference signal. The apparatus of claim 4 , wherein the indication of the resources is received in response to the transmission of the preamble.

6. The apparatus of claim 2, wherein the at least one reference signal comprises: At least one tracking reference signal.

7. The apparatus of any preceding claim, wherein the preamble indicates that the user equipment is requesting beam refinement of a transmission beam during the random access procedure, and the apparatus further comprises: means for determining, before sending the preamble, that the user equipment is in a low power state or does not have sufficient power to send all signaling for completing the random access procedure using the wide beam, wherein the preamble is sent in response to the determination.

8. A method for a user equipment, the method comprising: A preamble is sent to an access network node using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement on a transmission beam during the random access procedure.

9. The method of claim 8, wherein the preamble indicates that the user equipment is requesting beam refinement of a transmission beam during the random access procedure, and the method further comprises: receiving at least one reference signal from the access network node during the random access procedure; scanning the at least one reference signal to determine a transmission beam narrower than the wide beam; and sending signaling using the narrower transmission beam during the random access procedure.

10. The method of claim 9, wherein the signaling using the narrower transmission beam comprises: Physical uplink shared channel signaling.

11. The method according to any one of claims 9 or 10, further comprising: receiving, from the access network node, an indication of resources to be used for sending the at least one reference signal; and using the indication of the resource to locate the at least one reference signal.

12. The method of claim 11, wherein the indication of the resources is received in response to the transmission of the preamble.

13. The method of claim 9, wherein the at least one reference signal comprises: At least one tracking reference signal.

14. The method according to any one of claims 8 to 13, wherein the preamble indicates that the user equipment is requesting beam refinement of a transmission beam during the random access procedure, and the method further comprises: Prior to sending the preamble, it is determined that the user equipment is in a low power state or does not have sufficient power to send all signaling for completing the random access procedure using the wide beam, wherein the preamble is sent in response to the determination.

15. An apparatus for accessing a node, the apparatus comprising: Means for receiving a preamble from a user equipment using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement on a transmission beam during the random access procedure.

16. The apparatus of claim 15, wherein the preamble indicates that the user equipment is requesting beam refinement of a transmission beam during the random access procedure, and the apparatus further comprises: means for signaling at least one reference signal to the user equipment during the random access procedure; as well as means for receiving signaling from the user equipment during the random access procedure using a transmission beam narrower than the wide beam.

17. The apparatus of claim 16, wherein the signaling using the narrower transmission beam comprises: Physical uplink shared channel signaling.

18. The apparatus according to claim 16 or 17, wherein the apparatus further comprises: means for signaling to the user equipment an indication of resources to be used for sending the at least one reference signal.

19. The apparatus of claim 18, wherein an indication of the resources is signaled in response to the reception of the preamble.

20. The apparatus of claim 16, wherein the at least one reference signal comprises: At least one tracking reference signal.

21. A method for accessing a node, the method comprising: A preamble is received from a user equipment using wide beam transmission during a random access procedure, the preamble indicating whether the user equipment is requesting beam refinement on a transmission beam during the random access procedure.

22. The method of claim 21 , wherein the preamble indicates that the user equipment is requesting beam refinement of a transmission beam during the random access procedure, and the method further comprises: signaling at least one reference signal to the user equipment during the random access procedure; as well as Signaling is received from the user equipment using a transmission beam narrower than the wide beam during the random access procedure.

23. The method of claim 22, wherein the signaling using the narrower transmission beam comprises: Physical uplink shared channel signaling.

24. The method according to claim 22 or 23, wherein the method further comprises: An indication of resources to be used for sending the at least one reference signal is signaled to the user equipment.

25. The method of claim 24, wherein an indication of the resources is signaled in response to the receipt of the preamble.

26. The method of claim 22, wherein the at least one reference signal comprises: At least one tracking reference signal.

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