Channel access indication for spectrum reuse, power saving and coexistence

Abstract

Channel Access Indicator (CAI) can be adopted in New Radio Unlicensed (NR‑U) to indicate a node’s channel occupancy to nodes outside its cell, to indicate a node’s channel occupancy to nodes within its cell to help with spectrum reuse, and to trigger handshakes between nodes within a cell to ensure that the receiver has a clear channel for transmission and reception.

Description

Background Art

[0001] LTE License Assisted Access

[0002] Carrier aggregation with at least one SCell operating in unlicensed spectrum is called Licensed Assisted Access (LAA). Therefore, in LAA, the set of serving cells configured for a UE always includes at least one SCell operating in unlicensed spectrum according to frame structure type 3, also called LAA SCell. Unless otherwise specified, LAA SCell acts as a regular SCell, see "Practical LTE and Wi-Fi Coexistence Techniques beyond LBT", Jonathan Ling, David Lopez-Perez, Mohammad R.Kawer, IEEE Communications Magazine, October 2017.

[0003] The LAA eNB and UE apply Listen Before Talk (LBT) before performing transmissions on the LAA SCell. LBT is a method by which the radio transmitter first senses the medium and transmits only when the medium is sensed to be idle, which is also known as Clear Channel Assessment (CCA). When LBT is applied, the transmitter listens / senses the channel to determine whether the channel is idle or busy. If the channel is determined to be idle, the transmitter can perform a transmission; otherwise, it does not perform a transmission. If the LAA eNB uses channel access signaling of other technologies for LAA channel access, it should continue to meet the LAA maximum energy detection threshold requirement.

[0004] There are various LBT methods, but the one recommended by 3GPP is called Equipment Category 4 based on LBT load. This adds a random access protocol similar to WiFi to ensure not only LTE / WiFi coexistence, but also provides a standardized way to ensure LTE / LTE coexistence. In Release 14, several channel access procedures were introduced that can be performed by the eNB and UE for both downlink (DL) and uplink (UL) transmissions, respectively. The main channel access procedures are described in Section 15, Physical layer procedures (Release 15), V15.0.0 of 3GPP TS 36.213.

[0005] LTE frame structure type 3

[0006] Frame structure type 3 is applicable only for LAA secondary cell operation with normal cyclic prefix. Each radio frame T f =307200·T s = 10ms long and consists of 20 segments of length Tslot =15360·T s =0.5 ms, numbered 0 to 19. A subframe is defined as two consecutive time slots, where subframe i consists of time slots i and 2i+1.

[0007] 10 subframes within a radio frame can be used for downlink or uplink transmission. Downlink transmission occupies one or more consecutive subframes, starting anywhere within a subframe and ending when the last subframe is completely occupied or one of the DwPTS durations specified in Table 4.2-1 of 3GPP TS 36.213, Physical layer procedures (Release 15), V15.0.0 is followed. Uplink transmission occupies one or more consecutive subframes.

[0008] Next Generation Network Requirements

[0009] 3GPP TR 38.913, Study on Scenarios and Requirements for Next Generation Access Technologies (Release 14), V14.3.0 defines the scenarios and requirements for next generation access technologies. The key performance indicators (KPIs) for eMBB, URLLC, and mMTC devices are summarized in Table 1.

[0010] Table 1: KPIs for eMBB, URLLC, and mMTC devices

[0011]

[0012]

[0013] Receiver-Assisted Unlicensed Operation

[0014] In order to coordinate inter-technology spectrum access in a distributed and simple manner, the transmitter must first detect the energy across the intended transmission band. This energy detection (ED) mechanism informs the transmitter of ongoing transmissions by other nodes and helps it decide whether to transmit. However, although simple, this scheme, also known as listen before talk (LBT), does not work in all situations, for example, when the information is encoded to be received below the background noise level, or when the nodes are far away and the signal at the receiver is weak. Therefore, a node wishing to transmit can sense the channel as unoccupied based on the received energy being below a certain ED threshold, but still interfere with nearby nodes that are receiving.

[0015] Nevertheless, LBT is the starting point for coexistence and is mandatory in unlicensed band regulations in many countries. The ED threshold cannot be lowered too much because false detections will occur due to noise. Therefore, additional information is needed for efficient inter-technology and intra-technology wireless medium access.

[0016] RTS / CTS mechanism in WiFi

[0017] The 802.11 medium access control (MAC) protocol augments the ED mechanism with a virtual carrier sensing (VCS) mechanism, so that the 802.11 packet header is received and decoded at the lowest power level due to the use of the most robust modulation and decoding. The network allocation vector (NAV), i.e., the timeline at each station (STA) when the channel is idle or occupied, which indicates how long the channel will be used, is updated based on the content of such a header or control packet. For example, the request to send / clear to send (RTS / CTS) mechanism reserves the channel by having the NAV updated by all nodes that receive the RTS around the transmitter and the CTS around the receiver. However, even if there is a problem with VCS, it causes unfairness as a capture effect (which causes stronger overlapping packets to be captured before weaker packets) because stronger nodes do not experience conflicts and weaker nodes back off.

[0018] Virtual carrier sensing is a logical abstraction that limits the need for physical carrier sensing at the air interface in order to save power. The MAC layer frame header contains a duration field that specifies the required transmission time for the frame, during which the medium will be busy. A station listening to the wireless medium reads the duration field and sets its NAV, which is an indicator of how long the station must defer accessing the medium. The NAV can be thought of as a counter that decrements to zero at a uniform rate. When the counter is zero, the virtual CS indicates that the medium is idle; when non-zero, it indicates busy.

[0019] Unlicensed in LTE

[0020] There are two types of LTE access on unlicensed frequencies: LAA, which acts as a supplemental downlink to the licensed LTE carrier (note: the unlicensed uplink eLAA is still attached to the licensed carrier), and MulteFire, which features fully independent operation in the unlicensed band. In LAA, both the licensed and unlicensed bands operate simultaneously, i.e., data can be received on both bands at the same time. PBCH is carried only on the licensed carrier. However, the Rel-12 Discovery Reference Signal (DRS), including the PSS, is transmitted at 40ms intervals on the unlicensed carrier. Detecting the DRS alone does not provide further information, i.e., cell_ID, or even determine the operator. MulteFire transmissions do include PBCH / PDSCH in their downlink transmissions, now called ePBCH, which doubles the energy in the PSS and Secondary Synchronization Signal (SSS) sequences to improve detectability, see MultiFire version 1.0.1, www.multefire.org / specification. Summary of the invention

[0021] At the core of 3GPP NR Release 15 PHY is a beam-based architecture. It is highly expected that New Radio (NR) Unlicensed (NR-U) should leverage as many features as possible from NR, including the beam-based architecture. Unlike eLAA, where sensing is based on wide beams, narrow beam sensing can help coexistence by allowing efficient use of spatial resources; the LBT scheme can be enhanced to support carrier sense multiple access with collision avoidance (CSMA / CA) so that the UE can avoid unnecessary carrier busy detection, thereby improving power efficiency. NR-U may consider introducing signaling to indicate channel occupancy to improve spatial reuse and coexistence. This means that new methods and signal designs are required in NR-U.

[0022] Disclosed herein are methods and apparatus for using a channel access indicator in NR-U to provide functionality such as: indicating a node's channel occupancy to nodes outside its cell; and indicating a node's channel occupancy to nodes within its cell to aid in spectrum reuse; and triggering a handshake between nodes within the cell to ensure that the receiver has a clear channel for transmission and reception.

[0023] The behavior of a node when it receives a CAI is also disclosed, i.e., how the node uses a timer to wait to sense the channel. The information carried by the CAI for various use cases is also described.

[0024] Several procedures are also described to enable PUSCH to be transmitted at multiple starting positions within a UL grant, where the starting position is communicated to the gNB via the CAI. These methods include:

[0025] • A method to signal the PUSCH candidate starting positions.

[0026] ● The process of adjusting the UL DMRS based on the starting position selected by PUSCH.

[0027] ● The DMRS power can be boosted for the first PUSCH after the UE's COT.

[0028] ● The PUSCH RE can be power-boosted for the first PUSCH after the UE's COT.

[0029] • The UE may use different DMRS sequences to signal the selected PUSCH starting symbol.

[0030] ●The UE may use DMRS with higher resource density for the first PUSCH after the UE's COT.

[0031] • Puncturing process to adapt PUSCH to available resources.

[0032] ●Adjust the MCS based on the starting position of PUSCH selection and facilitate the process of detecting the selected MCS at the gNB.

[0033] ●The process for transmitting the carried UCI

[0034] PHY layer signaling techniques for enabling CAI transmission on DL and UL are also described. The PHY layer signaling techniques include:

[0035] ●PDCCH, PSS / SSS and other signals on DL;

[0036] PRACH, PUCCH on UL; and

[0037] ●Preamble-based transmission, including:

[0038] ● Partial indication of the CAI information on the preamble, and the remainder via a signal such as the PDCCH or PRACH;

[0039] Asynchronous with symbol timing; and

[0040] • Some bits of information either about the cell ID or about the channel occupancy time or about both are provided through repetition and OCC.

[0041] This summary is provided to introduce some concepts in a simplified form, which will be further described in the detailed description below. This summary is neither intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to limitations that address any or all disadvantages noted in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] A more detailed understanding can be obtained from the following description given by way of example in conjunction with the accompanying drawings.

[0043] Figure 1 Illustrated is a CAI transmission including (A) the CAI being read by a general purpose node and (B) indicating the time of channel occupancy.

[0044] Figure 2 The diagram illustrates sibling nodes affected by the LBT process based on the detection of high energy in the channel, including (A) a TDM UE of the cell - a later transmitting UE blocked by the first transmitting UE and (B) a UE multiplexed in the same time / frequency resources due to another blocked access channel.

[0045] Figure 3A CAI transmission for spectrum reuse between sibling nodes is illustrated.

[0046] Figure 3B Illustrated is changing the energy detection threshold when a CAI is detected from a sibling node during LBT.

[0047] Figure 3C It illustrates that LBT is terminated when CAI is detected from a sibling node and CCA is performed with a higher threshold.

[0048] Figure 3D The diagram illustrates CAI transmission on the UL by multiple UEs.

[0049] Figure 3E The transmission of CAI by the gNB is illustrated to indicate that the sibling node (UE) should use a higher threshold.

[0050] Figure 4 A method for performing CCA with a higher threshold when CAI is detected from a sibling node is illustrated.

[0051] Figure 5A A method for identifying intra-cell transmissions for spectral reuse is illustrated, wherein the threshold is switched to a higher value during LBT when a sibling node CAI is detected.

[0052] Figure 5BA method for identifying intra-cell transmissions for spectral reuse is illustrated, where CCA is performed with a higher threshold when a sibling node CAI is detected.

[0053] Figure 6 The diagram illustrates a method of handshaking using CAI-1 and CAI-R.

[0054] Figure 7 The diagram illustrates (A) handshaking using CAI-1 and CAI-R, (B) synchronizing the transmission of CAI with OFDM symbol boundaries, and (C) asynchronously transmitting CAI with OFDM symbol boundaries.

[0055] Figure 8 Diagram showing the use of T in CAI OCC Indicates channel occupation and release times.

[0056] Fig. 9 A method for sensing a channel (timer decrementing) upon receiving a CAI is illustrated.

[0057] Fig.10 The diagram shows the updated T OCC Periodic transmission of CAI.

[0058] Fig.11 The diagram shows the updated T REL Transmission of CAI.

[0059] Fig.12 The figure illustrates the transmission of CAI in UL during the channel occupancy time of the gNB.

[0060] Fig.13 The figure shows the T on different beams. OCC instruct.

[0061] Fig.14 A method of obtaining CAI transmitted through DCI is illustrated.

[0062] Fig.15 A method of transmitting CAI-R is illustrated.

[0063] Fig.16 The diagram shows the self-use of T according to CAI-1 Resp Duration of the CAI-R of the UE scheduled.

[0064] Fig.17 A method of receiving CAI by a sibling node and a general node in the case of using S-bit cell coloring is illustrated.

[0065] Fig.18 Illustrated is CAI transmission using preamble repetition with OCC code, including (A) synchronous with OFDM symbol boundaries and (B) asynchronous with symbol boundaries.

[0066] Fig.19 An example of preamble resources in frequency is illustrated.

[0067] Fig. 20 The CA resources in a cell using a composite carrier that is a multiple of 20 MHz are illustrated.

[0068] Fig.21A One embodiment of an example communication system is illustrated in which the methods and apparatus described and claimed herein may be implemented.

[0069] Fig. 21B is a block diagram of an example apparatus or device configured for wireless communication according to embodiments described herein.

[0070] Fig. 21C According to the embodiment Fig.21A System diagram of the RAN 103 and core network 106.

[0071] Fig.21D According to the embodiment Fig.21A System diagram of the RAN 104 and core network 107.

[0072] Fig.21E According to the embodiment Fig.21A System diagram of the RAN 105 and core network 109.

[0073] Fig.21F It can be implemented Fig.21A , 21C , 21D and 21E show a block diagram of an exemplary computing system for one or more devices of the communication network.

[0074] Figure 21G Multiple DCIs are shown, which provide multiple starting positions for PUSCH.

[0075] Fig. 22 It is shown that multiple DCIs providing multiple starting positions for PUSCH are transmitted in the same CORESET.

[0076] Fig.23 It is shown that multiple starting positions are configured relative to the time slot boundaries.

[0077] Fig.24 It is shown that multiple starting positions are configured relative to the starting position of the scheduled PUSCH.

[0078] Fig.25 It is shown that the PUSCH starts before 10 and the old DMRS configuration is still valid for the duration of the PUSCH, where the UE chooses the starting position.

[0079] Fig.26 It is shown that the PUSCH starts before 10 and the old DMRS configuration is invalid for the duration of the PUSCH, where the UE selects the starting position.

[0080] Fig. 27 It is shown that PUSCH starts after 10 and DMRS is mapped according to PUSCH mapping type B instead of PUSCH mapping type A.

[0081] Fig.28 It is shown that PUSCH starts after 10 and DMRS is mapped according to PUSCH mapping type B instead of PUSCH mapping type A.

[0082] Fig.29 The process of accessing a channel to transmit a PUSCH with multiple starting positions is shown.

[0083] Fig.30 An OFDM symbol carrying a UL DMRS of duration equal to the PUSCH duration is shown, where the starting position selected by the UE is the same as the old OFDM symbol carrying the UL DMRS of the originally scheduled PUSCH.

[0084] Fig.31 An OFDM symbol carrying the UL DMRS for the PUSCH is shown, where the starting position selected by the UE is different from the old OFDM symbol carrying the UL DMRS for the originally scheduled PUSCH.

[0085] Fig.32 The OFDM symbols carrying the UL DMRS for PUSCH are shown, where the starting position selected by the UE is different from the old OFDM symbol carrying the UL DMRS for the originally scheduled PUSCH and the last OS carries DMRS.

[0086] Fig.33 An OFDM symbol carrying UL DMRS for PUSCH is shown, where the starting position selected by the UE follows PUSCH mapping type B and is different from the old OFDM symbol carrying UL DMRS following PUSCH mapping type A for the originally scheduled PUSCH.

[0087] Fig.34 An OFDM symbol carrying UL DMRS for PUSCH is shown, where the starting position selected by the UE follows PUSCH mapping type B, while the old OFDM symbol carries UL DMRS following PUSCH mapping type A for the originally scheduled PUSCH.

[0088] Fig.35The power boost of DMRS REs for the first PUSCH transmission in the COT of the UE is shown.

[0089] Fig.36 The power boost of the remaining DMRS REs after dropping some DMRS REs due to channel unavailability is shown.

[0090] Fig.37 The starting position of PUSCH transmission indicated by DMRS sequence is shown (A) Sequence #1 indicates that PUSCH starts at OS #0 (B) Sequence #2 indicates that PUSCH starts at OS #1 (C) Sequence #3 indicates that PUSCH starts at OS #2 (D) Sequence #4 indicates that PUSCH starts at OS #4;

[0091] Fig.38 A higher DMRS resource density and different timing resources for DMRS in the first PUSCH transmission of the COT of the UE are shown.

[0092] Fig.39 A UL preamble is shown indicating the start of a PUSCH transmission.

[0093] Fig.40 The preamble resources in PUSCH are shown in (A) relative to PUSCH resources and (B) relative to carrier frequency bands.

[0094] Fig.41 It shows puncturing OFDM symbols during periods when the channel is unavailable and transmitting the remaining OFDM symbols after the channel is available.

[0095] Fig.42 The CA-RS-Group for CA-RS1 is shown: If LBT succeeds in the spatial direction indicated by CA-RS1, the gNB can transmit signals in the direction indicated by any RS in the corresponding CA-RS-Group.

[0096] Fig.43 The UL transmission corresponding to the spatial direction of the CA-RS-Group is shown.

[0097] Fig.44 It is shown that after detecting the preamble, the UE monitors the DCI in its monitoring opportunities.

[0098] Fig.45 A preamble indicating aperiodic CORESET / search space monitoring opportunities is shown.

[0099] Fig.46 It is shown that the preamble and CORESET resources share the same OS.

[0100] Fig.47It is shown that the gNB transmits preambles in multiple spatial directions to cover all UEs; the UE assumes that the DMRS of the corresponding CORESET is QCL with the preamble.

[0101] Fig.48 A UE is shown indicating the start of its channel access after the first PUSCH transmission which does not occupy granted resources due to channel availability.

[0102] Fig.49 It shows DMRS mapped according to PUSCH mapping type B based on the duration of PUSCH with a starting position selected by the UE, instead of PUSCH mapping type B with the original grant.

[0103] Fig.50A Candidate starting positions for multiple consecutive PUSCHs depending on each PUSCH are shown.

[0104] Fig.50B Candidate starting positions for multiple consecutive PUSCHs depending on the first symbol of the first PUSCH are shown.

[0105] Fig.50C Candidate starting positions for multiple consecutive PUSCHs relative to the boundaries of the time slots are shown.

[0106] Fig.50D Candidate starting positions for multiple consecutive PUSCHs relative to the boundaries of time slots with a specific pattern P are shown.

[0107] Fig.51 An example of moving the entire PUSCH to a new starting position is shown.

[0108] Fig.52A It is shown that the PUSCH and scheduled DMRS are shifted by two OFDM symbols relative to the original starting position, which is the same as the new starting position.

[0109] Fig.52B It is shown that one of the scheduled DMRS symbols is dropped because it falls outside the end of the scheduled PUSCH.

[0110] Fig.53A An example of shifting the PUSCH without crossing the slot boundary is shown.

[0111] Fig.53B An example of shifting multiple scheduled PUSCHs in a slot without crossing a slot boundary is shown.

[0112] Fig.54A An example of shifting the PUSCH while keeping the scheduled DMRS position fixed is shown.

[0113] Fig.54B An example is shown of shifting the PUSCH so that one of the scheduled DMRS symbols is dropped because it falls before the new starting position.

[0114] Fig.54C An example of transmitting a DMRS symbol in the first symbol of a PUSCH with a new starting position is shown, since all originally scheduled DMRS are dropped because they fall before the new starting position. DETAILED DESCRIPTION

[0115] The following is a list of acronyms that may appear in the following descriptions. Unless otherwise noted, the acronyms used in this article refer to the corresponding terms listed below:

[0116]

[0117]

[0118]

[0119] The Third Generation Partnership Project (3GPP) develops technical standards for cellular telecommunication network technologies, including radio access, core transport networks, and service capabilities - including work on codecs, security, and quality of service. Recent radio access technology (RAT) standards include WCDMA (commonly referred to as 3G), LTE (commonly referred to as 4G), and LTE-Advanced standards. 3GPP has begun work on the standardization of the next generation of cellular technology, which is called New Radio (NR), also known as "5G". The development of the 3GPP NR standard is expected to include the definition of the next generation radio access technology (new RAT), which is expected to include the provision of new flexible radio access below 6 GHz, and the provision of new ultra-mobile broadband radio access above 6 GHz. Flexible radio access is expected to include new, non-backward compatible radio access in new spectrum below 6 GHz, and is expected to include different operating modes that can be multiplexed together in the same spectrum to address a wide set of 3GPP NR use cases with different requirements. Ultra-mobile broadband is expected to include cmWave and mmWave spectrum, which will provide opportunities for ultra-mobile broadband access for, for example, indoor applications and hotspots. In particular, ultra-mobile broadband is expected to share a common design framework with sub-6 GHz flexible radio access, leveraging design optimizations specific to cmWave and mmWave.

[0120] 3GPP has identified a variety of use cases that NR is expected to support, resulting in various user experience requirements for data rates, latency, and mobility. Use cases include the following general categories: enhanced mobile broadband (e.g., broadband access in dense areas, ultra-high broadband access indoors, broadband access in crowds, ubiquitous 50+Mbps, ultra-low-cost broadband access, in-vehicle mobile broadband), critical communications, massive machine-type communications, network operations (e.g., network slicing, routing, migration and interworking, power saving), and enhanced vehicle-to-everything (eV2X) communications. Specific services and applications in these categories include, for example, surveillance and sensor networks, device remote control, two-way remote control, personal cloud computing, video streaming, wireless cloud-based offices, first responder connectivity, car ecalls, disaster alerts, real-time gaming, multi-person video calls, autonomous driving, augmented reality, tactile Internet, and virtual reality, among others. All of these use cases and others are considered in this article.

[0121] Fig.21A An embodiment of an example communication system 100 is illustrated in which the methods and apparatus described and claimed herein may be implemented. As shown, the example communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, and / or 102d (generally or collectively referred to as WTRUs 102), radio access networks (RANs) 103 / 104 / 105 / 103b / 104b / 105b, core networks 106 / 107 / 109, public switched telephone networks (PSTNs) 108, the Internet 110, and other networks 112, although it should be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d, 102e may be any type of device or apparatus configured to operate and / or communicate in a wireless environment. Although each WTRU 102a, 102b, 102c, 102d, 102e Figures 21A-21E , but it should be understood that for various use cases contemplated for 5G wireless communications, each WTRU may include or be implemented in any type of device or apparatus configured to transmit and / or receive wireless signals, including, by way of example only, a user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop, a tablet computer, a netbook, a notebook computer, a personal computer, a wireless sensor, a consumer electronics product, a wearable device (such as a smart watch or smart clothing), a medical or e-health device, a robot, an industrial equipment, a drone, a vehicle (such as a car, truck, train or airplane, etc.).

[0122] The communication system 100 may also include a base station 114a and a base station 114b. The base station 114a may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, and 102c to facilitate access to one or more communication networks (such as the core network 106 / 107 / 109, the Internet 110, and / or other networks 112). The base station 114b may be any type of device configured to wiredly and / or wirelessly interface with at least one of the RRHs (remote radio heads) 118a, 118b and / or TRPs (transmission and reception points) 119a, 119b to facilitate access to one or more communication networks (such as the core network 106 / 107 / 109, the Internet 110, and / or other networks 112). The RRHs 118a, 118b may be any type of device configured to interface with at least one of the WTRUs 102c to facilitate access to one or more communication networks, such as the core network 106 / 107 / 109, the Internet 110, and / or other networks 112. The TRPs 119a, 119b may be any type of device configured to interface with at least one of the WTRUs 102d to facilitate access to one or more communication networks, such as the core network 106 / 107 / 109, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be base transceiver stations (BTSs), Node-Bs (Node Bs), eNode Bs, home Node Bs, home eNode Bs, site controllers, access points (APs), wireless routers, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0123] The base station 114a may be part of the RAN 103 / 104 / 105, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. The base station 114b may be part of the RAN 103b / 104b / 105b, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, etc. The base station 114a may be configured to transmit and / or receive wireless signals within a specific geographic area, which may be referred to as a cell (not shown). The base station 114b may be configured to transmit and / or receive wired and / or wireless signals within a specific geographic area, which may be referred to as a cell (not shown). The cell may be further divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in an embodiment, the base station 114a may include three transceivers, for example, one transceiver for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and may therefore use multiple transceivers for each sector of the cell.

[0124] The base station 114a may communicate with one or more of the WTRUs 102a, 102b, 102c over an air interface 115 / 116 / 117, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, cmWave, mmWave, etc.). The air interface 115 / 116 / 117 may be established using any suitable radio access technology (RAT).

[0125] The base station 114b may communicate with one or more of the RRHs 118a, 118b and / or TRPs 119a, 119b via a wired or air interface 115b / 116b / 117b, which may be any suitable wired (e.g., cable, fiber optic, etc.) or wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, cmWave, mmWave, etc.). The air interface 115b / 116b / 117b may be established using any suitable radio access technology (RAT).

[0126] The RRHs 118a, 118b and / or the TRPs 119a, 119b may communicate with one or more of the WTRUs 102c, 102c via an air interface 115c / 116c / 117c, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, cmWave, mmWave, etc.). The air interface 115c / 116c / 117c may be established using any suitable radio access technology (RAT).

[0127] More specifically, as described above, the communication system 100 may be a multiple-access system and may employ one or more channel access schemes such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in the RAN 103 / 104 / 105 and the WTRUs 102a, 102b, 102c or the RRHs 118a, 118b and TRPs 119a, 119b in the RAN 103b / 104b / 105b and the WTRUs 102c, 102d may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish the air interface 115 / 116 / 117 or 115c / 116c / 117c, respectively. WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink Packet Access (HSDPA) and / or High Speed ​​Uplink Packet Access (HSUPA).

[0128] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c or the RRHs 118a, 118b and TRPs 119a, 119b and the WTRUs 102c, 102d in the RAN 103b / 104b / 105b may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may use Long Term Evolution (LTE) and / or LTE-Advance (LTE-A) to establish the air interface 115 / 116 / 117 or 115c / 116c / 117c, respectively. In the future, the air interface 115 / 116 / 117 may implement 3GPP NR technology.

[0129] In an embodiment, the base station 114a in the RAN 103 / 104 / 105 and the WTRUs 102a, 102b, 102c or the RRHs 118a, 118b and TRPs 119a, 119b in the RAN 103b / 104b / 105b and the WTRUs 102c, 102d may implement radio technologies such as IEEE 802.16 (e.g., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA20001X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM EDGE (GERAN), etc.

[0130] Fig.21A The base station 114c in the example may be, for example, a wireless router, a home Node B, a home eNode B, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a business location, a home, a vehicle, a campus, etc. In an embodiment, the base station 114c and the WTRU 102e may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114c and the WTRU 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114c and the WTRU 102e may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.) to establish a picocell or a femtocell. Fig.21A As shown in FIG, base station 114b may have a direct connection to the Internet 110. Therefore, base station 114c may not be required to access the Internet 110 via core network 106 / 107 / 109.

[0131] The RAN 103 / 104 / 105 and / or the RAN 103b / 104b / 105b may be in communication with a core network 106 / 107 / 109, which may be any type of network configured to provide voice, data, applications, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. For example, the core network 106 / 107 / 109 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions (such as user authentication).

[0132] Although not in Fig.21A 105b and / or the core network 106 / 107 / 109 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 103 / 104 / 105 and / or the RAN 103b / 104b / 105b or a different RAT. For example, in addition to being connected to the RAN 103 / 104 / 105 and / or the RAN 103b / 104b / 105b, which may utilize an E-UTRA radio technology, the core network 106 / 107 / 109 may also be in communication with another RAN (not shown) that employs a GSM radio technology.

[0133] The core network 106 / 107 / 109 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d, 102e to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and the Internet Protocol (IP) in the TCP / IP Internet Protocol suite. The networks 112 may include wired or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another core network connected to one or more RANs, which may employ the same RAT as the RAN 103 / 104 / 105 and / or the RAN 103b / 104b / 105b or a different RAT.

[0134] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities, e.g., the WTRUs 102a, 102b, 102c, 102d, and 102e may include multiple transceivers for communicating with different wireless networks via different wireless links. Fig.21A The WTRU 102e shown in FIG. 1 may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114c, which may employ an IEEE 802 radio technology.

[0135] Figure 1 B is a block diagram of an example apparatus or device (such as, for example, WTRU 102) configured for wireless communication according to the embodiments described herein. Fig. 21BAs shown in , the example WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad / indicator 128, a non-removable memory 130, a removable memory 132, a power supply 134, a global positioning system (GPS) chipset 136, and other peripherals 138. It should be appreciated that the WTRU 102 may include any sub-combination of the foregoing elements while remaining consistent with the embodiments. Moreover, the embodiments contemplate that the base stations 114a and 114b, and / or the nodes that the base stations 114a and 114b may represent (such as, but not limited to, a transceiver station (BTS), a Node B, a site controller, an access point (AP), a home node-B, an evolved home node-B (eNodeB), a home evolved node-B (HeNB), a home evolved node-B gateway, and a proxy node, etc.), may include Fig. 21B Some or all of the elements depicted in and described herein.

[0136] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Fig. 21B The processor 118 and the transceiver 120 are depicted as separate components, but it will be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0137] The transmission / reception element 122 may be configured to transmit signals to a base station (e.g., base station 114a) or receive signals from a base station (e.g., base station 114a) via an air interface 115 / 116 / 117. For example, in an embodiment, the transmission / reception element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmission / reception element 122 may be a transmitter / detector configured to, for example, transmit and / or receive IR, UV, or visible light signals. In yet another embodiment, the transmission / reception element 122 may be configured to transmit and receive RF and light signals. It should be appreciated that the transmission / reception element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0138] In addition, although the transmit / receive element 122 is Fig. 21BAlthough depicted as a single element in the figure, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in an embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 115 / 116 / 117.

[0139] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As described above, the WTRU 102 may have multi-mode capabilities. Thus, for example, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs, such as UTRA and IEEE 802.11.

[0140] The processor 118 of the WTRU 102 may be coupled to a speaker / microphone 124, a keypad 126, and / or a display / touchpad / indicator 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit), and may receive user input data therefrom. The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad / indicator 128. In addition, the processor 118 may access information from and store data in any type of suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. In an embodiment, the processor 118 may access information from and store data in a memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0141] The processor 118 may receive power from the power source 134 and may be configured to distribute power to and / or control other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries, solar cells, fuel cells, etc.

[0142] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 115 / 116 / 117 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information by any suitable location-determination method while remaining consistent with an embodiment.

[0143] The processor 118 may also be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include various sensors such as accelerometers, biometric (e.g., fingerprint) sensors, electronic compasses, satellite transceivers, digital cameras (for photos or videos), universal serial bus (USB) ports or other interconnect interfaces, vibration devices, television transceivers, hands-free headsets, modules, FM radio units, digital music players, media players, video game player modules, internet browsers, etc.

[0144] The WTRU 102 may be implemented in other devices or equipment, such as sensors, consumer electronics, wearable devices (such as smart watches or smart clothing), medical or e-health equipment, robots, industrial equipment, drones, vehicles (such as cars, trucks, trains or airplanes), etc. The WTRU 102 may be connected to other components, modules or systems of such devices or equipment via one or more interconnect interfaces (such as an interconnect interface that may include one of the peripheral devices 138).

[0145] Fig. 21C 1 is a system diagram of the RAN 103 and the core network 106 according to an embodiment. As described above, the RAN 103 may employ UTRA radio technology to communicate with the WTRUs 102a, 102b, and 102c over the air interface 115. The RAN 103 may also be in communication with the core network 106. Fig. 21CAs shown in FIG. 1 , the RAN 103 may include Node-Bs 140a, 140b, 140c, each of which may include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 115. The Node-Bs 140a, 140b, 140c may each be associated with a particular cell (not shown) within the RAN 103. The RAN 103 may also include RNCs 142a, 142b. It will be appreciated that the RAN 103 may include any number of Node-Bs and RNCs while remaining consistent with an embodiment.

[0146] like Fig. 21C As shown, Node B 140a, 140b can communicate with RNC 142a. In addition, Node B 140c can communicate with RNC 142b. Node B 140a, 140b, 140c can communicate with corresponding RNC 142a, 142b via Iub interface. RNC 142a, 142b can communicate with each other via Iur interface. Each of RNC 142a, 142b can be configured to control the corresponding Node B 140a, 140b, 140c connected thereto. In addition, each of RNC 142a, 142b can be configured to perform or support other functions, such as outer loop power control, load control, admission control, packet scheduling, handover control, macro diversity, security functions, data encryption, etc.

[0147] Fig. 21C The core network 106 shown in FIG. 1 may include a media gateway (MGW) 144, a mobile switching center (MSC) 146, a serving GPRS support node (SGSN) 148, and / or a gateway GPRS support node (GGSN) 150. Although each of the foregoing elements is depicted as part of the core network 106, it should be appreciated that any of these elements may be owned and / or operated by an entity other than a core network operator.

[0148] The RNC 142a in the RAN 103 may be connected to the MSC 146 in the core network 106 via an IuCS interface. The MSC 146 may be connected to the MGW 144. The MSC 146 and the MGW 144 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices.

[0149] The RNC 142a in the RAN 103 may also be connected to the SGSN 148 in the core network 106 via an IuPS interface. The SGSN 148 may be connected to the GGSN 150. The SGSN 148 and the GGSN 150 may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0150] As described above, core network 106 may also be connected to networks 112, which may include other wired or wireless networks owned and / or operated by other service providers.

[0151] Fig.21D 1 is a system diagram of the RAN 104 and the core network 107 according to an embodiment. As described above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, and 102c over the air interface 116. The RAN 104 may also be in communication with the core network 107.

[0152] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In an embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a.

[0153] Each of the eNode-Bs 160a, 160b, and 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the uplink and / or downlink, etc. Fig.21D As shown in FIG. , the eNode-Bs 160a, 160b, 160c may communicate with each other via an X2 interface.

[0154] Fig.21DThe core network 107 shown in FIG. 1 may include a mobility management gateway (MME) 162, a serving gateway 164, and a packet data network (PDN) gateway 166. While each of the foregoing elements is depicted as part of the core network 107, it should be appreciated that any of these elements may be owned and / or operated by an entity other than a core network operator.

[0155] The MME 162 may be connected to each of the eNode-Bs 160a, 160b, and 160c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, etc. The MME 162 may also provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM or WCDMA.

[0156] The serving gateway 164 may be connected to each of the eNode-Bs 160a, 160b, and 160c in the RAN 104 via an S1 interface. The serving gateway 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The serving gateway 164 may also perform other functions, such as anchoring the user plane during an inter-eNode B handover, triggering paging when downlink data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0157] The serving gateway 164 may also be connected to the PDN gateway 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0158] The core network 107 may facilitate communications with other networks. For example, the core network 107 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, and 102c and traditional land-line communications devices. For example, the core network 107 may include, or may be in communication with, an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the core network 107 and the PSTN 108. In addition, the core network 107 may provide the WTRUs 102a, 102b, and 102c with access to the networks 112, which may include other wired or wireless networks that are owned and / or operated by other service providers.

[0159] Fig.21E 1 is a system diagram of the RAN 105 and the core network 109 according to an embodiment. The RAN 105 may be an access service network (ASN) that employs IEEE 802.16 radio technology to communicate with the WTRUs 102a, 102b, and 102c over the air interface 117. As discussed further below, the communication links between the different functional entities of the WTRUs 102a, 102b, 102c, the RAN 105, and the core network 109 may be defined as reference points.

[0160] like Fig.21E As shown in the figure, the RAN 105 may include base stations 180a, 180b, 180c and an ASN gateway 182, but it should be appreciated that the RAN 105 may include any number of base stations and ASN gateways while remaining consistent with the embodiment. The base stations 180a, 180b, 180c may each be associated with a particular cell in the RAN 105 and may include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 117. In an embodiment, the base stations 180a, 180b, 180c may implement MIMO technology. Thus, the base station 180a, for example, may use multiple antennas to transmit wireless signals to the WTRU 102a and receive wireless signals from the WTRU 102a. The base stations 180a, 180b, 180c may also provide mobility management functions, such as handover triggering, tunnel establishment, radio resource management, traffic classification, quality of service (QoS) policy enforcement, and the like. The ASN gateway 182 may serve as a traffic aggregation point and may be responsible for paging, caching of subscriber profiles, routing to the core network 109, and the like.

[0161] The air interface 117 between the WTRUs 102a, 102b, 102c and the RAN 105 may be defined as an R1 reference point that implements the IEEE 802.16 specification. In addition, each of the WTRUs 102a, 102b, and 102c may establish a logical interface (not shown) with the core network 109. The logical interface between the WTRUs 102a, 102b, 102c and the core network 109 may be defined as an R2 reference point, which may be used for authentication, authorization, IP host configuration management, and / or mobility management.

[0162] The communication link between each of the base stations 180a, 180b, and 180c may be defined as an R8 reference point, which includes protocols for facilitating WTRU handover and data transfer between the base stations. The communication link between the base stations 180a, 180b, 180c and the ASN gateway 182 may be defined as an R6 reference point. The R6 reference point may include protocols for facilitating mobility management based on mobility events associated with each of the WTRUs 102a, 102b, 102c.

[0163] like Fig.21E As shown in , the RAN 105 may be connected to a core network 109. The communication link between the RAN 105 and the core network 109 may be defined as an R3 reference point, which includes protocols for facilitating, for example, data transfer and mobility management capabilities. The core network 109 may include a mobile IP home agent (MIP-HA) 184, an authentication, authorization, accounting (AAA) server 186, and a gateway 188. While each of the foregoing elements is depicted as part of the core network 109, it will be appreciated that any of these elements may be owned and / or operated by an entity other than the core network operator.

[0164] The MIP-HA may be responsible for IP address management and may enable the WTRUs 102a, 102b, and 102c to roam between different ASNs and / or different core networks. The MIP-HA 184 may provide the WTRUs 102a, 102b, and 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, and 102c and IP-enabled devices. The AAA server 186 may be responsible for user authentication and supporting user services. The gateway 188 may facilitate interworking with other networks. For example, the gateway 188 may provide the WTRUs 102a, 102b, and 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, and 102c and traditional land-line communication devices. In addition, the gateway 188 may provide the WTRUs 102a, 102b, and 102c with access to the networks 112, which may include other wired or wireless networks that are owned and / or operated by other service providers.

[0165] Although not in Fig.21E 105 may be connected to other ASNs and the core network 109 may be connected to other core networks. The communication link between the RAN 105 and the other ASNs may be defined as an R4 reference point, which may include protocols for coordinating the mobility of the WTRUs 102a, 102b, 102c between the RAN 105 and the other ASNs. The communication link between the core network 109 and the other core networks may be defined as an R5 reference point, which may include protocols for facilitating interworking between a home core network and a visited core network.

[0166] This article describes and Fig.21A , 21C The core network entities shown in 21D and 21E are identified by the names given to those entities in certain existing 3GPP specifications, but it should be recognized that in the future, those entities and functions may be identified by other names, and that certain entities or functions may be combined in future specifications published by 3GPP (including future 3GPP NR specifications). Fig.21A , 21B The specific network entities and functions described and illustrated in 21C, 21D and 21E are provided as examples only, and it should be understood that the subject matter disclosed and claimed herein may be implemented or realized in any similar communication system, whether currently defined or defined in the future.

[0167] Fig.21F is a block diagram of an exemplary computing system 90 in which Fig.21A ,21C , 21D and 21E, such as certain nodes or functional entities in the RAN 103 / 104 / 105, the core network 106 / 107 / 109, the PSTN 108, the Internet 110 or other networks 112. The computing system 90 may include a computer or a server and may be primarily controlled by computer-readable instructions, which may be in the form of software, wherever or in any manner such software is stored or accessed. Such computer-readable instructions may be executed within the processor 91 to enable the computing system 90 to operate. The processor 91 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 91 may perform signal encoding, data processing, power control, input / output processing, and / or any other function that enables the computing system 90 to operate in a communication network. Coprocessor 81 is an optional processor distinct from main processor 91 that may perform additional functions or assist processor 91. Processor 91 and / or coprocessor 81 may receive, generate, and process data related to the methods and apparatus disclosed herein.

[0168] In operation, processor 91 fetches, decodes and executes instructions, and transfers information to and from other resources via the computing system's main data transfer path, system bus 80. Such a system bus connects components in computing system 90 and defines a medium for data exchange. System bus 80 typically includes data lines for sending data, address lines for sending addresses, and control lines for sending interrupts and for operating the bus. An example of such a system bus 80 is a PCI (Peripheral Component Interconnect) bus.

[0169] The memory coupled to the system bus 80 includes a random access memory (RAM) 82 and a read-only memory (ROM) 93. Such memory includes a circuit system that allows information to be stored and retrieved. ROM 93 generally contains stored data that is not easily modified. The data stored in RAM 82 can be read or changed by a processor 91 or other hardware device. Access to RAM 82 and / or ROM 93 can be controlled by a memory controller 92. The memory controller 92 can provide an address translation function that translates a virtual address into a physical address when an instruction is executed. The memory controller 92 can also provide a memory protection function that isolates processes within the system and isolates system processes from user processes. Therefore, a program running in the first mode can only access memory mapped by its own process virtual address space; unless memory sharing between processes has been set up, it cannot access memory within the virtual address space of another process.

[0170] In addition, the computing system 90 may include a peripheral device controller 83 that is responsible for transmitting instructions from the processor 91 to peripheral devices such as a printer 94 , a keyboard 84 , a mouse 95 , and a disk drive 85 .

[0171] The display 86 controlled by the display controller 96 is used to display the visual output generated by the computing system 90. Such visual output may include text, graphics, animated graphics, and video. The visual output may be provided in the form of a graphical user interface (GUI). The display 86 may be implemented with a CRT-based video display, an LCD-based flat panel display, a gas plasma-based flat panel display, or a touch pad. The display controller 96 includes the electronic components required to generate the video signal sent to the display 86.

[0172] Additionally, computing system 90 may include communications circuitry, such as a network adapter 97, which may be used to connect computing system 90 to an external communications network, such as a Fig.21A , 21B , RAN 103 / 104 / 105 of 21C, 21D and 21E, core network 106 / 107 / 109, PSTN 108, Internet 110 or other network 112) to enable computing system 90 to communicate with other nodes or functional entities of those networks. Alone or in combination with processor 91, the communication circuit system can be used to perform the transmission and reception steps of certain devices, nodes or functional entities described herein.

[0173] Introduction of Channel Access Indicator (CAI) in NR-U

[0174] According to one aspect of the systems and methods disclosed herein, NR-U may support channel access indication using a channel access indicator (CAI), which may be signaled to indicate information about channel occupancy, such as the cell occupying it, the occupied bandwidth / spatial direction, the occupied time, etc.

[0175] An NR-U node is a node capable of transmitting and receiving in the NR-U band. The following terms are introduced to distinguish the types of nodes in the NR-U channel.

[0176] ● Sibling Node – A node served by the same serving NR-U cell as the reference node. More specifically, a sibling node of a given node may be defined as any co-channel node or any co-channel user having the same serving cell as the given node. NOTE: A co-channel transmission may be an UL transmission by a given UE or a DL transmission to a given UE. S Used to denote a generic sibling node. In other words, a node that is in the same NR-U serving cell as the reference node is considered a sibling node. This includes the gNB of the serving cell.

[0177] ● Generic Node – A node that is not served by the same NR-U cell as the reference node. This can include a node within another NR-U cell of the same PLMN, or another cell from a different PLMN, or nodes from other technologies such as WiFi. More specifically, a generic node with respect to a given node may be defined as any co-channel node or any co-channel user with a different serving cell, or as any co-channel UE with a different serving cellular RAT or a different non-cellular RAT than the given node. NOTE: A co-channel transmission may be a UL transmission by a given UE or a DL transmission to a given UE. Node g Used to represent generic nodes.

[0178] CAI can serve one or more of the following purposes:

[0179] • Use case 1: Indication of network occupancy for coexistence.

[0180] ● Use case 2: Allows nodes to identify intra-cell transmissions and improve spectrum reuse.

[0181] ● Use case 3: Triggering a handshake from the receiver to ensure that access to the channel is not hindered by hidden nodes.

[0182] • Use case 4: Power savings by allowing a receiver to identify when its transmitter is transmitting.

[0183] Use case 1: Using CAI to indicate network occupancy for coexistence

[0184] When sibling nodes and general nodes detect CAI, they can obtain the time of channel occupancy from CAI; therefore they do not need to perform channel sensing during the occupancy time. Figure 1 (A) shows an example where the gNB transmits CAI in Cell1, indicating the source of the transmission, i.e., Cell1 is occupying the transmission. It can also indicate its occupation time of the channel. Node UE1 from Cell1 recognizes it as an intra-cell transmission. General nodes (such as UE2 from NR-U Cell2, gNB2 on NR-UCell2) recognize it as a transmission from a node outside its cell, but can read the occupation time. Node3 in the WiFi network may have the ability to detect and read CAI from the NR-U network. General nodes cannot perform LBT until the occupation time of Cell1 has passed. Figure 1 (B) shows this method for responding to a general node after hearing CAI from Cell1, where the node resumes CCA (clear channel assessment) after the Cell1 channel occupancy time. CCA is initial channel sensing, where energy detection (ED) is performed at least at a certain threshold for a certain time.

[0185] In general, CAI can be signaled in both DL and UL. In autonomous UL (AUL) and semi-persistent scheduling, the UE may be semi-statically configured for its resources. There is no guarantee that the UE's resources are within the MCOT of its gNB. In this case, the UE may perform a method similar to CAT 4 LBT to determine channel availability and transmit CAI in the UL after a successful LBT.

[0186] Use case 2: Using CAI to indicate spectrum reuse

[0187] When a node identifies that a channel is occupied by another node in its own cell, it can adjust its energy detection threshold accordingly – if the energy is coming from a sibling node, it can use a higher energy detection threshold than the lower threshold it would normally use in CCA without CAI. To determine the LBT failure. Figure 4 The method in illustrates this concept.

[0188] This feature is particularly useful in the UL where multiple UEs are multiplexed in frequency or time and allows better spatial reuse. When a UE detects intra-cell usage and high energy in the channel, the CAI will enable it to transmit because the detected energy is from the multiplexed intra-cell UEs. Sibling nodes share the same channel resources through multiplexing. They can be multiplexed onto the same time / frequency resources, or multiplexed only in time, or multiplexed only in frequency, or multiplexed in both time and frequency. For example, in NR UL, multiple UEs (orthogonally) share PUCCH resources, multiple UEs share resources in NOMA non-orthogonally, or multiple UEs are time / frequency multiplexed for PUSCH. Taking the example of two sibling nodes multiplexed in time, such as Figure 2 As seen in (A), UE1 has UL transmission in mini-slot #1 while UE2 has UL transmission in mini-slot #2. UE2 is blocked due to the energy level from UE1. Similarly, if both sibling nodes are multiplexed in the same frequency and time resources for PUCCH and perform CAT 4 LBT for transmission, then UE1 can access the channel earlier. The random backoff of UE2 may be larger, so it listens to UE1 and assumes that it cannot access the channel, as shown in Figure 2. Figure 2 As seen in (B). If sibling node UE2 performs energy detection, it detects the energy from UE1 and cannot transmit in the scheduled resources. Therefore, within the NR-U cell, although the multiplexed nodes should be able to transmit in the scheduled resources, they will fail CCA / LBT due to the higher energy level from other sibling nodes.

[0189] like Figure 3A As seen in FIG, UE1 transmits CAI. UE2 recognizes sibling node transmission after hearing the CAI and transmits the multiplexed PUSCH it has scheduled.

[0190] In order to ensure that other UEs, especially multiplexed sibling node UEs, hear the UE's CAI, this paper proposes to use a method similar to CAT 4 LBT - which allows UEs to back off randomly. The UE that first gains access to the channel transmits the CAI, and other UEs with larger backoffs hear this CAI. Figure 3B and Figure 3C As shown in , UE1 obtains channel access and transmits its CAI before UE2. UE2 starts with The channel is sensed with CCA as part of CAT 4 LBT. As it continues to sense the channel during its random backoff period, it detects higher energy. Therefore, UE2 listens for CAI. It detects CAI and identifies it as an intra-cell transmission. At this point, UE2 can do one of the following:

[0191] ●UE2 changes its LBT threshold to And continue to extend the sensing with this higher threshold. If the energy is within this threshold, then it will transmit its PUSCH scheduled in FDM resources with UE1. Figure 3A (B) is shown. Figure 5A Available in.

[0192] ●UE2's change ends its current LBT and resets its random backoff timer. It uses Perform CCA, which is typically a short procedure (such as 25μs CCA). If it succeeds, UE2 continues with its scheduled PUSCH transmission. Figure 3C This method is shown in Figure 5B Available in.

[0193] If the UE does not receive CAI from a sibling node, it may transmit its own CAI. Figure 3D An example is shown where UE2 does not hear the CAI from UE1 and transmits its own CAI. Other sibling node UEs or gNBs may hear both the CAI of UE1 and UE2. Therefore, the CAI from multiple UEs may collide in time / frequency. According to one aspect, by using orthogonality / low correlation between CAI from different UEs, the UL CAI design can be robust to collisions. One way to obtain orthogonality is to provide different frequency resources for the CAI of different UEs. Another way to provide robustness is through sequences with good cross-correlation properties, such as PRACH.

[0194] CAI may also be signaled by the gNB on Cell1 to indicate the occupancy time. CAI may implicitly indicate to Cell1 that UEs scheduled or configured to transmit during this occupancy time may do so with a higher CCA threshold. Figure 3E In the example, upon receiving CAI from their gNBs, UE1 and UE2 perform a single instance CCA and use a higher threshold To determine channel access.

[0195] For UEs, the thresholds for LBT energy level sensing can be configured by the gNB as part of the UL grant, or through RRC in a cell-wide or UE-specific manner. For example, if two UEs are multiplexed on frequency, where UE1 occupies 80% of the frequency resources and UE2 occupies the remaining 20%, then the LBT energy level used by UE2 is It can be higher than UE1. gNB can configure V threshIt may indicate the actual value to be used as the index of the table. The index may be signaled in a DCI format such as 1_1, 0_1, 1_0, or 0_0. If the BWP for the UE is not configured to support a field for indicating an index, the UE may Applies to LBT regardless of whether it detects the CAI of a sibling node.

[0196] It can also provide the value of the RRC configuration used in certain scenarios - for example, since the gNB does not know the number of UEs that can access it, V thresh Configured to a specific value for PRACH signaling.

[0197] Alternatively, the UE may derive its threshold implicitly from the reference threshold configured for the BWP.If the UE occupies a portion of the bandwidth part, it may scale the reference threshold by that portion.

[0198] CAI may be used as a reservation signal to ensure efficient use of the spectrum.

[0199] Figure 4 The general process at a node after receiving a CAI from a sibling node is shown.

[0200] Use Case 3: Handshake between Tx and Rx using CAI to overcome hidden nodes

[0201] The CAI from the transmitter indicates that the channel is available at the transmitter. It can also request a handshake from the receiver to ensure that the channel is available at the receiver before scheduling a large payload. This helps to solve the problem of hidden nodes near the receiver. In this case, the CAI from the transmitter can be defined as CAI Initiation (CAI-I) and the CAI response from the receiver can be defined as CAI Response (CAI-R). If the CAI-R is not received at the initiating node, then it is assumed that the LBT of the responder has failed, in which case the initiator cannot transmit to the responder until later. CAI-I and CAI-R can be sent by both the gNB and the UE.

[0202] When the gNB sends CAI-I, it may wait for CAI-R before scheduling a grant to the UE. CAI-1 may be transmitted after the Cat 4 LBT because the initiating node intends to use the channel to transmit payload to the responding node. Sensing at the responding node may take the form of CCA (which may be short interval sensing, such as 25μs sensing in LTE, unlicensed for DRS in FR1), which is short and reduces the possibility of other nodes occupying the channel during the sensing period.

[0203] Figure 6 A method for establishing a handshake between two nodes is shown.

[0204] Figure 7 (A) illustrates the concept of handshake between two sibling nodes, where the gNB initiates CAI-1 and the UE responds with CAI-R. The UE may also transmit CAI-1 on the UL, especially when performing CAT 4 LBT procedures. If the channel to the gNB is clear, the gNB may respond with CAI-R, after which the UE transmits an UL signal, such as PUSCH or PUCCH.

[0205] like Figure 7 As shown in (B), CAI-R can be synchronized with codeword boundaries. To achieve this, the responding node transmits a reservation signal after LBT. Assuming that the originating node has codeword boundary alignment, it receives CAI-R. Synchronous transmission is useful when the amount of information carried in CAI is high and requires to be carried in a signal such as PDCCH or PUCCH.

[0206] Alternatively, if Figure 7 As shown in (C), CAI-1 and CAI-R can be transmitted asynchronously with code element boundaries. CAI can carry only a few bits of information, and can be detected by time correlation (such as with the preamble) to signal, in which case the asynchronous transmission of CAI preferably keeps the latency low. Especially for CAI-R, this can keep the latency of completing the handshake at a minimum level. The responding node can transmit a reservation signal after the CAI-R to reserve the channel at least for the duration spent by the initiating node detecting the channel, so that no other node will occupy the channel. The initiating node can then transmit to the responding node without performing LBT again. Therefore, the reservation signal can be transmitted after transmitting the CAI-R.

[0207] The reservation signal may be generated by repeating the CAI-R signal for a desired duration.

[0208] Since the gNB can use CAI-R to assess the UE's environment when other multiplexed UEs are transmitting, the gNB may occasionally trigger CAI-R for a given UE and use the result to determine future scheduling. The UE may also transmit the detected energy level (during LBT) back to the gNB. This helps detect the impact of interference from sibling UEs on a given UE in the UL; the gNB can make decisions about multiplexed UEs (orthogonal or non-orthogonal) based on CAI-R. In this case, the UE may be configured with resources for CAI-R by RRC, but the CAI-R is only transmitted when the UE receives a trigger via CAI-I.

[0209] Use Case 4: Using CAI to Enable Power Savings

[0210] A receiver node such as a UE (e.g. a gNB in ​​a low power state) can monitor the channel occupancy of its transmitter, where it monitors only the CAI. After receiving the CAI, the receiver switches to the nominal power state, where it monitors the control channel, data channel, and reference signals from the transmitter. After the COT expires, the receiver can return to the low power state to monitor the CAI.

[0211] Methods related to CAI

[0212] The timing of CAI dissemination

[0213] If Node1 transmits CAI at time tms, then T REL ms is defined as the time it takes for Node1 to release the channel. Therefore, T REL =t+T OCC , where T OCC ms is the indication time of channel occupancy. REF It can be defined as the duration of a known interval (such as a time slot or OFDM symbol or subframe or half-frame) in the reference numerology. For the remaining discussion, consider that the time slot duration with respect to the reference numerology is given by T REF Example. OCC (in ms) can be defined as T REF Therefore, CAI can use D bits to indicate T with respect to the reference time slot duration. OCC .

[0214] Node1 can obtain the maximum T OCC , whose value is T OCC =T MCOT , where T MCOT is the time of MCOT of Node1 for that channel access instance, and T MCOT The priority class may be based on the LBT used in channel access. In this case, it may not be possible to transmit the M bit for MCOT alone.

[0215] Figure 8 The T in CAI is given OCC Here, Node1 is represented by T MCOT =10ms to access the channel and transmit CAI in time slot N of the frame. Node1 intends to use the channel for 7 time slots and then release it. Therefore, CAI indicates T OCC =7ms, assuming T REF =1ms.

[0216] Node S and Node g You can use the following method to OCCOn Node S and Node g After receiving the CAI, the channel availability timer is set to T OCC Assume that Node S and Node g Know T REF Each T REF The counter is decremented. S and Node g The channel is expected to be available when the timer reaches 0.

[0217] CAI can be transmitted at the beginning of a time slot to ensure that the channel is actually released when the counter is reset. However, it is not always possible to transmit CAI at the beginning of a time slot. In addition, to account for propagation delays and receiver latency to decode CAI, Node S and Node g The channel can be monitored. A typical setting may use c=1.

[0218] Fig. 9 A method of using a timer at a general node is shown.

[0219] Furthermore, for a higher probability of detectability and to ensure that UEs with different DRX configurations can still receive CAI, CAI may be transmitted periodically or multiple times in a known pattern within the COT. A UE may not be configured to receive every instance of CAI; therefore, multiple instances improve the chances of receiving CAI. Fig.10 An example is shown in FIG. 1 , where CAI is sent in time slots #0 and #5 of a frame. Both CAIs indicate the same T REL , but in time slot #5 T OCC Decremented by 5, indicating that 5 slots have passed since the CAI transmission in slot #0.

[0220] It is also proposed in this paper that Node1 can increase or decrease its expected occupation time within its MCOT and indicate this update in the subsequent CAI. Fig.11 An example is shown, where the first CAI transmitted when the channel is available is T OCC =7ms. The next CAI transmission is performed by incrementing it by 2ms to the updated T OCC =4ms to change. S and Node g When the first CAI is received, the channel availability timer is set to T OCC , and each time slot (T REF ms) decreases. In this example, T REFWhen the second CAI is received, the timer is updated to T OCC =4ms new value, then the counter is decremented until it reaches one or zero, then Node and Node g Try to access the channel.

[0221] Generally speaking, this approach can be applied if a new CAI is received from any cell – when a node detects a new CAI, it updates the channel availability timer value to T OCC The latest value of , and start every T REF ms decrement timer.

[0222] UL transmission within MCOT of gNB

[0223] When a transmitter such as a gNB occupies a channel, it indicates its T OCC , thus providing However, at T OCC It may allow the UE to transmit on the UL for a duration of T. In addition, the UE may transmit UL CAI to indicate intra-network operations to other UEs that may also attempt to access the channel, or it may transmit CAI-R if the gNB requests a response. In this case, it is proposed in this document that the UL CAI will be T OCC Instructions to The time of the channel occupancy is not the duration of its channel occupancy.

[0224] Fig.12 An example is shown, where the UL transmission from UE1 is only one time slot, but its UL CAI indicates T OCC = 2ms, making Node S and Node g The channel availability timer at It decreases and is not affected by UL CAI.

[0225] In this paper, it is proposed that the UE may have T from DL CAI or CAI-1. REL knowledge, or it can be received through authorization Explicit value of .

[0226] CAI with omnidirectional and spatial LBT

[0227] If omnidirectional LBT is performed, then the channel can be accessed on multiple beams simultaneously. In this paper, it is proposed that the node can have a different T for each beam. OCC , while the MCOT is the same for all beams. CAI can be sent on multiple beams to indicate the occupancy of the channel, including T for each beam. OCCHowever, if all beams have the same T OCC , then only one field may be required to indicate the T used for all beams. OCC .

[0228] If spatial LBT is performed, the gNB can have different T REL In this case, the CAI may carry the T for each beam. OCC Therefore, a receiver receiving one of the CAIs can know the network occupancy in multiple spatial directions without detecting CAI on other beams. This can save some computational overhead. The spatial direction can be indicated as spatial QCL relative to one of the signals in DRS or SSB, such as PBCH DMRS or a CSI-RS in DRS. Fig.13 An example is shown where the gNB has gained channel access on beams B1 and B2. However, for beams T OCC are different. The CAI transmitted on B1 and B2 indicates the values ​​for both beams. Also, the CAI on some beams may be CAI-1 and may carry a trigger for handshake, while the CAI on other beams may not carry a trigger signal and may not indicate channel occupancy. Also, the location of the CAI may be different on different beams even if the gNB obtains channel access to these beams at the same time, since the gNB may have to sweep the beams to transmit the CAI.

[0229] Information carried in CAI

[0230] The following information can be carried in CAI:

[0231] ● The field cellID can be related to the NCellID of the gNB. It can be 10 bits and exactly equal to the NCellID. Alternatively, The number of bits obtained by operations such as , where L can be a power of 2 such as 64 or 128 – this allows the overhead to be kept small while allowing different cells to be distinguished. The cellID helps the listening node identify the cell occupying the channel.

[0232] ●T bit transmitter ID field transmitterID

[0233] ○ If the gNB (TRP in the network) is transmitting, then the T bit can be set to a value in one of the following ways

[0234] ■Fixed value common to all NR-U networks

[0235] ■ Cell-specific values ​​provided in the cell's SI.

[0236] ■T=0; if the field may not be present, it implicitly indicates that it comes from the gNB.

[0237] ○ If the UE is transmitting, then the T bit is set to a value based on its ID This ID may be an ID such as a C-RNTI or CS-RNTI, or a part of a C-RNTI or CS-RNTI, which is configured by the network to which it is attached.

[0238] ●An R-bit receiver ID field receiverID, where R can be equal to T.

[0239] ■ If the gNB (TRP in the network) is receiving, then the R bit can be set to the value A fixed value common to all NR-U networks, via one of the following methods:

[0240] ■ Cell-specific values ​​provided in the cell's SI.

[0241] ■T=0; if the field may not be present, it implicitly indicates that it comes from the gNB.

[0242] o If the UE is receiving, then set the value based on the receiver ID (such as C-RNTI or CS-RNTI or part of C-RNTI or CS-RNTI)

[0243] ●The one-bit field responseIndicator, when set to 1, can indicate whether CAI requires a CAI-R response from the receiver. When set to 0, CAI does not require a CAI-R from the receiver.

[0244] ●CAI-I can carry a P-bit field resourceCAIR to indicate the resources used to transmit CAI-R.

[0245] ●CAI-I can carry a U-bit field triggeredUEID to indicate the ID of the UE that must respond with CAI-R.

[0246] ● The CAI-R may carry a field detEnergy of E bits to indicate the energy detected during the LBT preceding the CAI-R. The number of bits E can be kept small by assigning predefined thresholds for different energy levels. Knowing the energy detected by the responding node can help the initiating node assess the environment of the responder, especially when multiple nodes are multiplexed together. Thus, an initiating node such as a gNB can set the threshold level for LBT at the responding node.

[0247] The following fields may be defined for each numBeam whose information the CAI carries. For omnidirectional LBT, numBeams = 1; therefore, the following fields use a single instance. For spatial LBT, numBeam may be defined in the specification for different unlicensed bands in FR1 and FR2, or configured in the SI of the cell; numBeams may be set to the number of SSBs in the cell. The instances in the payload may be sorted in ascending order of the SSB index.

[0248] ● The intendedChannelOccTime field uses D bits to indicate the channel occupancy T OCC This may be indicated in the form of a timeslot number in reference numerology, such as 15 KHz for FR1 and 120 KHz for FR2.

[0249] ● Field mcotTransmitter, which indicates the duration T MCOT ms MCOT. It is given by M bits, so that T OCC ≤T MCOT .

[0250] • The field freqResourceMCOT indicates the frequency resource on which the channel will be accessed. This allows a listening node to access channels outside the indicated frequency band.

[0251] In general, since CAI is signaled for different purposes (such as indicating occupied time or usage or handshaking in the network), it may carry different fields and different amounts of information depending on the use case.

[0252] The CAI on one cell can indicate the channel occupancy on other aggregated NR-U cells. For example, an NR-UPCell / PSCell can indicate its own CAI together with other aggregated NR-U SCells.

[0253] Candidate PUSCH starting position

[0254] Performing LBT before UL PUSCH imposes uncertainty on when the UE will be able to access the channel. Therefore, allowing the UE to have multiple starting positions in one or more time slots is beneficial to cope with channel uncertainty.

[0255] The following two aspects must be considered to support variable starting position(s) of PUSCH.

[0256] a. Signaling candidate starting positions for PUSCH: The burden on the gNB to detect the starting positions must be minimized. The gNB can limit the number of starting positions for the first PUSCH transmission from the UE within the UE’s COT to simplify the hardware requirements for detecting PUSCH.

[0257] b. UE's UL channel access indication: Indication of the UE's starting position. Based on the set of allowed starting positions, the UE can indicate the selected starting position of the first PUSCH transmission within its COT. Therefore, CAI can be transmitted by the UE on the UL to indicate the expected time of channel occupancy. The UL CAI can be explicitly indicated by a new signal such as RS or preamble sequence, or it can be implicitly indicated by an existing signal such as DMRS of PUSCH. By detecting the UL CAI, the gNB identifies the starting position of the UE's PUSCH. For example, if the presence of DMRS can unambiguously indicate the starting position, the gNB can detect the starting position of the UE's PUSCH by detecting and processing the UE's DMRS (autocorrelation or cross-correlation). Otherwise, the gNB can detect it via energy detection on the received PUSCH symbol by symbol.

[0258] Signaling candidate starting positions for PUSCH

[0259] The gNB can potentially detect the presence of a PUSCH transmission by detecting the DMRS signal from the UE. However, the gNB must determine the start of the PUSCH transmission, which can vary depending on the channel access of the UE. The gNB can blindly decode the PUSCH for all candidate PUSCH start OSs. For example, consider that the UL grant is for a slot of 14 OSs. But the UE can only get channel access from OS#2, and the PUSCH is punctured for OS#0 and OS#1. The gNB then receives the transmission and decodes assuming that the PUSCH starts at OS#0, if that fails, it can decode for PUSCH start position OS#1, if that fails, it can decode for PUSCH start position OS#2, and so on until it successfully decodes the PUSCH. If it cannot decode, then it assumes that it starts at OS#0 of the slot, buffers the PUSCH, and schedules a retransmission for the PUSCH. Assuming the retransmission is received in its entirety, the gNB can decode via catch-up combining assuming the original transmission started at OS#0, if that fails, the gNB can decode via catch-up combining assuming the original transmission started at OS#1, if that fails, the gNB can decode via catch-up combining assuming the original transmission started at OS#2 – if this attempt succeeds, the transmission is stopped. This blind decoding process incurs excessive hardware complexity for the gNB.

[0260] Furthermore, it can be seen that it is advantageous to enable the gNB to know the starting position of the PUSCH to minimize blind decoding. If the information is made available at the time of the PUSCH itself transmission through a signal such as the CAI transmitted at the start of the PUSCH, then the gNB can avoid blind decoding while handling retransmissions through catch-up combining. However, even if the CAI cannot be made available to the gNB when processing the PUSCH, if the CAI information can be transmitted to the gNB prior to the scheduled retransmission, then it will also enable the gNB to reduce blind decoding when handling retransmissions. According to one aspect, the UE may transmit its channel access information through a preamble or UCI; this may indicate when its COT starts, and furthermore, it may also indicate when the UE's COT ends. The gNB identifies the starting position of the PUSCH from this and identifies the punctured symbols in the original transmission before it is catch-up combined with the retransmission. This concept is discussed in detail in the GNB documentation. Fig.48 , where the start of COT is indicated by the UE via UCI on PUSCH; this occurs after the end of the first PUSCH transmission starting on OS#2.

[0261] In order to make the overhead of blind decoding acceptable at the gNB, the UE may be restricted from transmitting PUSCH starting from certain starting positions. A method is disclosed herein in which the gNB may transmit multiple DCIs similar to DCI format 0_0 or 0_1 to provide the UE with multiple starting positions of the PUSCH, as well as associated parameters (such as UL DMRS configuration, MCS, TPC, etc.) for different PUSCH starting positions. To this end, for example, the gNB may use the same values ​​of the new data indicator (NDI) and the redundancy version (RV) on multiple DCIs, but it may adjust fields such as time domain resource assignment, MCS, TPC, etc. In this case, the UE may interpret the reception of multiple UL grants with the same NDI and RV values ​​as alternatives, and the UE may use only one of the UL grants based on the result of LBT on the UE side and ignore the other UL grants. In order to provide the UE with sufficient processing time to prepare for the PUSCH based on the starting position, an earlier DCI may be associated with a UL grant with an earlier starting position. For example, Figure 21G Three DCIs are shown, which provide different starting positions for PUSCH, and the UE can deploy only one of them based on the LBT result at the UE side.

[0262] Alternatively, all DCIs may be transmitted in the same CORESET, e.g. Fig. 22Those DCIs may carry the same NDI and RV to indicate that the provided UL grants are alternatives to each other, and the UE may select only one grant and ignore the other provided grants. The UE may first use the UL grant providing the largest amount of resources, followed by the UL grant providing the second largest amount of resources, and so on.

[0263] A new field of 1-bit size field in the DCI, for example, called DCI repeat flag, which can indicate that all DCIs carrying the same RV and NDI with the repeat flag set to one are alternatives to each other, and the UE can choose to use the grant provided by only one of these DCIs. In contrast, if the repeat flag is set to zero, one DCI can overwrite the other DCI. Here, the UE does not choose which DCI to use, instead, the gNB determines the DCI that can be used according to the following rules, for example:

[0264] ● DCI transmitted in a later CORESET may overwrite DCI transmitted in an earlier CORESET; and

[0265] • If DCI is transmitted in the same CORESET, the DCI transmitted in the lowest PRB may overwrite the DCI transmitted in a higher PRB.

[0266] According to another aspect, a single DCI may provide multiple starting positions. For example, the following information may be transmitted with this DCI, with a C-RNTI scrambled CRC (other RNTIs may be used whenever applicable):

[0267] • Number of starting positions, which indicates the number of candidate PUSCH starting positions that the UE may use based on the LBT results. The size of this field may be defined by a higher layer parameter (eg, an RRC parameter called maxNumStartPosit).

[0268] ● or / and For each candidate starting position, a dedicated time domain resource assignment may be used to signal the starting position of each candidate PUSCH starting position. The bit width of this field is determined by bits, where I is the number of entries in the higher layer parameter pusch-TimeDomainAllocationList multiplied by the number of starting positions indicated in the above-mentioned field.

[0269] ●Or / and an MCS field for each candidate starting position, and the bit width of this field is the number of starting positions indicated in the above-mentioned field multiplied by the number of bits required to convey the MCS for each starting position respectively.

[0270] ● Or / and For all candidate PUSCH starting positions, NDI and RV may be the same.

[0271] • Antenna Port field for each candidate PUSCH starting position.

[0272] To reduce the overhead of transmitting multiple DCIs to indicate different starting positions for PUSCH, the UE may select one of multiple candidate positions given by a higher-level parameter, such as an RRC parameter named PUSCH-start-Positions-set. The set candidate positions may be relative to the timeslot or relative to the scheduled PUSCH. If PUSCH-start-Positions-set is relative to the timeslot, the UE may select a candidate starting position from those that overlap with the original PUSCH grant. Fig.23 An example of PUSCH-start-Positions-set is shown, which provides multiple PUSCH start positions relative to the time slot at codeword {0,2,5,8,10}. In this example, PUSCH is scheduled to start from OS 4. Depending on the LBT result on the UE side, the PUSCH start position can be at the beginning of the UL grant, as indicated by the DCI, or at one of the candidate start positions (which are codewords {5,8,10}) that overlap with the grant.

[0273] Alternatively, the candidate start positions may be given by a higher layer parameter (such as an RRC parameter PUSCH-start-Positions-set) relative to the original start position of the PUSCH given in the UL grant. In other words, the index of the actual symbol of the candidate start position is given by PUSCH-start-Positions-set after being shifted relative to the index of the first symbol in the UL grant. If some of the indices of the actual symbols of the candidate start positions are beyond the end position of the scheduled PUSCH, the UE may ignore those candidate positions. As an illustration, Fig.24 An example is shown where PUSCH-start-Positions-set = {2, 5, 7}, and the original starting position provided by the UL grant is symbol 4. Therefore, the actual candidate starting positions are {6, 9, 11}, and the UE attempts to access the channel at any of those positions based on the LBT results.

[0274] Moreover, in order to avoid signaling the candidate starting positions, they can be defined according to some rules either with respect to the time slot boundaries or with respect to the PUSCH grant itself. For example, every even / odd codeword can be a candidate starting position. In yet another example, the candidate starting position can follow a certain pattern, like every L codewords after the first codeword in the granted PUSCH or time slot, for example, L=1 means that every other codeword is a candidate starting position. The value of L can depend on several parameters in the PUSCH grant, such as the duration of the grant, MCS, etc. For example, if L depends on the MCS, then it can be given by Table 2.

[0275] Table 2 Candidate starting positions according to scheduled MCS

[0276]

[0277] In Table 2, I MCS is the MCS for a given DCI providing a PUSCH grant, and for i∈{1,…,N}, MCS th_i It can be provided by a higher layer parameter such as the RRC parameter PUSCH-start-Positions-th. If the higher layer parameter indicates that the MCS thresholds in any row are equal, that is, MCS th_(i-1) =MCS th_i , then disable L for the associated rows where both MCS thresholds appear.

[0278] Table 3 illustrates an example of the number of starting positions and the dependency of their positions on the duration of the scheduled PUSCH. In this example, if the duration of the PUSCH grant is 3 symbols or less, then L can be set to zero to indicate that the UE can attempt to access the channel at every symbol. But if the duration of the PUSCH grant is 4 symbols, then L can be set to 1, which means that the UE can attempt to access the channel every other symbol, and so on. The value of L for different PUSCH grant durations can be given by advanced parameters.

[0279] Table 3 Candidate starting positions according to scheduled PUSCH duration

[0280]

[0281] Other mathematical rules may also be applied to define the index of the candidate starting positions, such as the OFDM symbol whose index (l) satisfies l modM=0, where M may depend on some of the original PUSCH grant parameters, such as MCS, duration of the grant (in symbols), etc. In order to establish the functional dependency of M on any original PUSCH grant parameters, a table similar to Table 2 may be used, for example. If any of the aforementioned rules are applied with respect to slot boundaries, the UE may only consider candidate starting positions that overlap with UL grants.

[0282] On the other hand, explicit (using high-level parameters) and implicit (according to specified rules) indication of candidate starting positions can be combined. For example, the candidate starting position can be the union of the positions given explicitly and implicitly. Moreover, in the absence of an explicit indication of the candidate starting position, the UE can apply the implicit indication.

[0283] It should be understood that the above-mentioned solutions and / or any possible combination thereof can be extended to provide the UE with multiple possible candidate starting positions of scheduled continuous or non-continuous PUSCHs through either a single or multiple UL grants. As a possible solution, the RRC parameters can provide the UE with the positions of (one or more) candidate starting positions. These positions can be relative to the scheduled PUSCH or relative to the time slot boundary. The UE can then only consider the positions overlapping with the scheduled PUSCH.

[0284] Fig.50A The example shows that the candidate starting position is configured as a shift from the first OFDM symbol in each scheduled PUSCH, and the shift value may be indicated by higher layer signaling (such as RRC parameters). Fig.50A As shown in , the shift value may depend on the PUSCH index. For example, in PUSCH k, the candidate starting position is determined by S k Separated by k, where k is the index of the PUSCH. The UE may be indicated by higher layer signaling with shift values ​​for consecutive PUSCHs, for example, a set of shift levels such as {a, b, c, d, ...} may be indicated to the UE. The UE may then set S0 = a for PUSCH 0, S1 = b for PUSCH 1, and so on. Alternatively, the UE may be indicated by higher layer signaling with a single parameter, which the UE may use to derive the position of the candidate starting position for each PUSCH, for example, it may vary according to the PUSCH index number.

[0285] Alternatively, for example, Fig.50BAs shown in , the candidate PUSCH starting positions can be separated by a shift S starting from the first OFDM symbol in the first scheduled PUSCH. Other rules can also be applied to define the positions of the candidate starting positions. Moreover, in addition to those indicated by high-level signaling, the UE can also regard the first OFDM symbol of each PUSCH as a candidate starting position.

[0286] Fig.50C The case where the candidate starting positions are defined relative to the time slot boundaries is illustrated. The number and positions of the candidate starting positions may be the same across each time slot, or may vary from one time slot to another. The high-level signaling may indicate these positions. In addition to the first OFDM symbol in each PUSCH, the UE may also regard the candidate starting position overlapping with any scheduled PUSCH as a valid candidate starting position, which the UE may use to attempt to access the channel, while other candidate starting positions outside the scheduled PUSCH are invalid and the UE will not attempt to access the channel at those positions. The high-level layer may indicate the index of the OFDM symbol in each time slot that the UE may use as a candidate starting position, for example, if the corresponding bit is set to one, then a 14-bit size bitmap may indicate which OFDM symbols may be used as candidate starting positions. Moreover, each time slot in a subframe / radio frame may have a different position for the candidate starting position, the concatenated bitmap for each time slot may be signaled to the UE, and the position of the candidate starting position is repeated in each subframe or radio frame. Furthermore, the gNB may define a pattern over a certain number of slots, where one group of slots has a certain candidate starting position and other groups have different candidate positions. This pattern may be applied repeatedly. For example, Fig.50D A pattern P=101 over 3 time slots is shown, where the time slot corresponding to 1 has four candidate starting positions, and the time slot corresponding to 0 has 2 candidate starting positions. This pattern is repeated every three time slots.

[0287] The gNB may semi-statically indicate a specific set of configurations for candidate starting positions to enable the gNB to flexibly adjust these configurations. For example, the gNB may provide the UE with multiple higher layer configurations indicating different sets of candidate starting position arrangements, and the gNB may then select the appropriate configuration using MAC-CE, for example by pointing to a higher layer message ID carrying these configurations.

[0288] In addition, the gNB can dynamically indicate the appropriate configuration of candidate starting positions by using DCI. For example, a length equal to A bit field of K, where K is the number of configurations indicated by higher layer signaling. This bit field may be indicated in the DCI carrying the grant(s) or in a separate DCI in a UE-specific search space or in a group common search space with the appropriate RNTI. Furthermore, the gNB may use MAC-CE to signal a subset of candidate starting locations to the UE, and the gNB may then use DCI to indicate the configuration of the selection of the candidate starting locations.

[0289] UL channel access indication by UE

[0290] Adjust DMRS scheduling based on PUSCH starting position

[0291] For PUSCH mapping type A, the position(s) of the DMRS symbols are defined relative to the slot boundaries, which can lead to ambiguous behavior if the UE fails to acquire the channel according to the scheduled / configured grant. For example, if multiple starting positions are provided by multiple dedicated DCIs, as shown in Figures 21 and Fig. 22 As shown in , i.e., a one-to-one mapping of DCIs to different starting PUSCH positions, then each DCI can carry appropriate DMRS scheduling information, depending on the starting position of the PUSCH, which is combined with the DMRS RRC configuration. However, this can require a lot of overhead in terms of signaling and UE power consumption to decode multiple DCIs for the same grant. Therefore, in order to alleviate this burden, it can be more useful to signal the candidate starting positions explicitly (using high-level parameters) or implicitly (according to specified rules) than using multiple DCIs. However, such static configuration may not be sufficient to adjust the DMRS scheduling based on the starting position of the PUSCH selected by the UE. Next, several embodiments that address this challenge are described.

[0292] For Single UE MIMO (SU-MIMO), several alternatives can be employed.

[0293] PUSCH starts before l0

[0294] If the UE accesses a channel before l0 given by the higher layer parameter dmrs-TypeA-Position (see 3GPP TS 36.211, Physical channels and modulation (Release 15), V15.3.0) before l0, the UE may deploy the configured and scheduled UL DMRS as long as the DMRS symbol of the PUSCH of the starting position selected by the UE and its new duration are the same as the DMRS symbol of the PUSCH with the old duration. For example, if the PUSCH duration is equal to 10, 11 or 12 OFDM symbols, the DMRS occupies symbols l0, 9, as shown in Table 4 (see 3GPP TS 36.211, Physical channels and modulation (Release 15), V15.3.0).

[0295] Table 4 DMRS positions for PUSCH mapping type A for single-symbol DMRS with dmrs-AdditionalPosition=1 and intra-slot hopping disabled

[0296] Duration (in code units) DMRS location 10 <![CDATA[l0,9]]> 11 <![CDATA[l0,9]]> 12 <![CDATA[l0,9]]>

[0297] Fig.25 An example is shown for a PUSCH that is scheduled for transmission over 12 OFDM symbols from OS 0 to OS 11 with one additional UL DMRS symbol, but the UE cannot access the channel due to LBT failure. If the channel becomes available starting from the candidate positions OS 1 and OS 2 shown in the figure, the duration of the PUSCH with the starting position selected by the UE is 11 and 10 respectively. Therefore, the UE can still use the same scheduled DMRS.

[0298] On the other hand, if the duration of the PUSCH with the UE-selected starting position uses a different DMRS configuration than the original PUSCH duration, the UE may follow the new DMRS configuration associated with the new PUSCH duration with the same number of additional DMRS symbols. Fig.26An example of a PUSCH is shown that was originally scheduled to have a duration of 10 symbols from OS 0 to OS 9 with one additional UL DMRS symbol, but the UE cannot access the channel at OS 0. However, if the UE accesses the channel at OS 1 or OS 2, then the duration of the PUSCH with the UE-selected starting position is 9 and 8, respectively. Therefore, the UE may not use the old DMRS configuration associated with the original PUSCH grant, but the UE may use the new DMRS configuration associated with the PUSCH duration of 8 and 9 OFDM symbols. In this case, the DMRS should be located in OS l0,7 as shown.

[0299] PUSCH starts from l0 or after l0

[0300] If the UE accesses the channel starting from or after symbol 10 given by the higher-level parameter dmrs-TypeA-Position, the UE may assume that PUSCH mapping type A (where DMRS is mapped relative to the slot boundary) is effectively changed to PUSCH mapping type B (where DMRS is mapped relative to PUSCH based on the new PUSCH duration). In other words, the UE may set l0 to zero and map DMRS according to the new PUSCH duration and the number of additional DMRS symbols given by the higher-level parameter dmrs-additionalPosition. Fig. 27 An example is shown for a PUSCH that is scheduled for transmission over 12 OFDM symbols from OS 0 to OS 11 with one additional UL DMRS symbol, but the UE fails to access the channel due to LBT failure. If the channel becomes available starting from the candidate position shown in the figure (i.e., OS 5), the duration of the PUSCH with the starting position selected by the UE is 7 OFDM symbols. In this case, as shown in the figure and Table 5, the UE can map the UL DMRS according to the new PUSCH duration of 7 OS following mapping type B in l0 and 4 relative to the start of the PUSCH.

[0301] Table 5 PUSCH DMRS positions for PUSCH mapping types A and B

[0302]

[0303] As another example, Fig.28A PUSCH is shown that is scheduled for transmission over 12 OFDM symbols from OS 0 to OS 11, with one additional UL DMRS symbol, but the UE fails to access the channel due to LBT failure. In this example, the UE accesses the channel starting from OS 7, which results in a duration of four OFDM symbols for the PUSCH with a UE-selected starting position, of which there is only one symbol carrying DMRS, and no additional DMRS position.

[0304] Although in the previous examples, these aspects are described on a single-symbol DMRS with one additional DMRS position, these aspects are still applicable to single-symbol DMRS with any additional number of DMRS positions, and also to dual-symbol DMRS with any additional number of DMRS positions.

[0305] Fig.29 An example process is illustrated in which the DMRS configuration may be adjusted based on the candidate PUSCH starting position. Fig.29 In the example of , first, the gNB transmits a request for granting PUSCH mapping type A and schedules the corresponding DMRS based on the PUSCH duration. Next, the UE attempts to access the channel to start the PUSCH from the first scheduled OS. If the channel is available, the process ends. If the channel is not available, the UE attempts to access the channel at a new starting position. To access the channel before Io, the UE selects a UL DM R5 configuration based on PUSCH mapping type A and the new PUSCH duration, but has the same configuration as the scheduled DMRS in terms of OM RS type (1 or 2), number of additional DMRS positions, and single or double DMRS symbols. To not access the channel before Io, the UE selects a UL DM R5 configuration based on PUSCH mapping type B and the new PUSCH duration, but has the same configuration as the scheduled DMRS in terms of DMRS type (1 or 2), number of additional DMRS positions, and single or double DMRS symbols. In either case, the UE transmits PUSCH with the new DMRS configuration.

[0306] The case of multi-user MIMO (MU-MIMO) (i.e., other UEs' DMRS are sharing the same CDM group with different OCC sequences or using orthogonal frequency resources) is more challenging because the UEs are sharing the same resources for PUSCH. Therefore, shifting one UE's DMRS independently of other UEs' DMRS can lead to significant interference between different antenna ports used by different UEs. To address this challenge, several alternatives can be adopted as described below.

[0307] The UE may change the starting position of the PUSCH as long as the UL DMRS symbol(s) of the PUSCH with the UE-selected starting position occupies the same symbol(s) or some of those symbols that carried the UL DMRS of the old PUSCH. For example, for PUSCH mapping type A with single-symbol DMRS with three additional DMRS positions, if the PUSCH duration is 12, 13 or 14, then the DMRS occupies the same symbols 10, 5, 8, 11. Thus, for example, if the original PUSCH grant duration is 14 symbols and three additional DMRS are configured, such as Fig.30 As shown in , UE1 can try to access the channel starting from OS1 or 2, which makes the duration of the PUSCH with the UE-selected starting position equal to 13 and 12 codewords, respectively. For both PUSCH starting positions, the UL DMRS can occupy the same codewords as the UL DMRS of the originally scheduled PUSCH. In this case, even after changing the starting position for UE1 PUSCH, the DMRS of UE1 and UE2 are still orthogonal.

[0308] It is not always the case that the UL DMRS occupies the same symbols for the PUSCH with the UE selected starting position and the originally scheduled PUSCH. Therefore, according to another aspect, the symbol index set S of the UL DMRS carrying the PUSCH with the old duration is to be selected from old The index set S of the OFDM symbol carrying the UL DMRS of the PUSCH with the new duration is selected new If two sets do not overlap and belong to S new Some of the indices of old , then replace those indices with S old The closest index in S old Symbols of the UL DMRS in the UE that are not used to transmit the PUSCH with the new duration cannot be used to carry data to avoid collision between them and the DMRS of other UEs. Fig.31 An example of a PUSCH grant equal to a duration of 12 symbols from OS 0 to OS11 is shown, where three additional DMRS are configured to occupy, i.e., S old ={l0,5,8,11}. If UE1 attempts to access the channel starting from OS 1 or OS 2, this makes the duration of PUSCH with the UE-selected starting position 11 and 10 respectively. Unfortunately, during the duration of PUSCH with the UE-selected starting position, the UL DMRS must occupy symbol S new= {l0,6,9}, which means that only l0 overlaps with the symbol carrying the UL DMRS of UE2. Moreover, the UE can use S of 5 and 8 respectively. old Replace S with the closest index in new 6 and 9 in the table have S new ={l0,5,6,8,9}. By doing so, the orthogonality between UE1 and UE2 is maintained.

[0309] To avoid extrapolation over many OFDM symbols, which would severely degrade the channel estimate from the last DMRS to the last OFDM symbol at the end of the PUSCH, if more than one OFDM symbol is needed to carry a PUSCH with the new duration, the index of the last OFDM symbol of the PUSCH can be used with the old duration. old = {l0,5,8,11} and S new ={l0,6,9}, the UE can new 6 and 9 in are replaced by 5 and 11 respectively to have S new ={l0,5,6,11,9}, such as Fig.32 as shown in .

[0310] If PUSCH mapping type A is used, but the UE acquires the channel after 10, then PUSCH mapping type B may be used to map the DMRS according to the duration of the PUSCH with a starting position selected by the UE. If the symbol index set S carrying the UL DMRS for the PUSCH with the new duration new Unlike the symbol index set assumed to carry the ULDMRS for PUSCH with the old duration, S new Each element in is replaced by S old The closest element in . Fig.33 An example of a PUSCH grant equal to a duration of 12 symbols from OS 0 to OS 11 is shown, where three additional DMRS are configured to occupy, i.e., S old ={l0,5,8,11}. If UE1 fails to access the channel starting from OS0, but succeeds starting from OS7 (i.e., after l0), DMRS mapping according to PUSCH mapping type B can be used. Since the new PUSCH duration is five symbols, the UL DMRS can occupy the symbols indexed by l0,4 relative to the PUSCH starting position OS7, so S new = {7,11}. new With S old By comparison, UE can replace OS7 with OS8 to make S new ={8,11}.

[0311] If the UE accesses the channel at OS8, the new PUSCH duration is 5, and according to PUSCH mapping type B, the index of the symbol carrying DMRS relative to PUSCH is l0, that is, S new = {8}. In this case, S cannot be used old The last symbol in carries DMRS, such as Fig.34 as shown in .

[0312] In addition, the UE may shift the entire scheduled PUSCH to a new starting position, and the scheduled DMRS may be shifted relative to the new starting position, instead of just starting PUSCH transmission from the new starting position without shifting the entire PUSCH, e.g. Fig.51 as shown in . Fig.52A An example is shown for a PUSCH that is scheduled for transmission over 12 OFDM symbols from OS 0 to OS 11 with one additional UL DMRS symbol, but the UE fails to access the channel due to LBT failure. If the channel becomes available starting from the candidate position OS 2 shown in the figure, i.e., the PUSCH start position is shifted by two OFDM symbols. The DMRS symbols are then shifted by two OFDM symbols so that their new positions are OS 5 and OS 11. Since the entire PUSCH is shifted, the UE can puncture / rate match the truncated symbols at the end of the granted PUSCH.

[0313] Depending on the new starting position, if one or more of the UE's new shifted positions are beyond the end of the scheduled PUSCH, the UE may puncture one or more of the scheduled DMRS symbols. Fig.52B An example of a UE transmitting only one DMRS symbol instead of the originally scheduled two DMRS symbols is shown. The DMRS symbol is scheduled for transmission in OS 3, and the UE may transmit it in OS 11. The DMRS symbol scheduled for transmission in OS 9 may be discarded.

[0314] For example, the UE may be configured to transmit at least one DMRS symbol in the first OFDM symbol in the new PUSCH starting position. This may be beneficial if all scheduled DMRS symbols are shifted beyond the end of the scheduled PUSCH, i.e., all scheduled DMRS symbols are discarded. In the case where no scheduled DMRS symbols can be transmitted due to the shifted PUSCH, the higher layer signaling may indicate the minimum number of DMRS symbols, their positions, etc. Furthermore, the UE may be configured to not transmit this PUSCH if the remaining number of OFDM symbols carrying the PUSCH is less than a certain threshold, since it is most likely to be successfully decoded. Such a threshold may be indicated to the UE via higher layer signaling.

[0315] If PUSCH is not allowed to cross slot boundaries and a UE is scheduled with multiple consecutive PUSCHs, then each scheduled PUSCH cannot be shifted beyond the end of the slot containing the originally scheduled PUSCH. Fig.53A An example of N PUSCHs scheduled by a UE is shown, and three candidate starting positions are indicated for PUSCH 0. PUSCH 0 may then be shifted to start from any of the indicated candidate starting positions based on channel availability. For example, if the channel is not available at any of the indicated candidate PUSCH starting positions or the remaining number of OFDM symbols in slot 0 is less than a certain threshold indicated by higher layers, the UE may discard PUSCH 0. The UE may then attempt to access the channel to transmit the next PUSCH.

[0316] If a timeslot contains multiple PUSCHs, the UE may, for example, Fig.53B As shown, all scheduled PUSCHs are shifted within the time slot. In this figure, PUSCH 0 is dropped because the channel is not available. Therefore, the UE can try to access the channel to transmit PUSCH 1. If the channel is not available, then PUSCH 1 and the subsequent PUSCH 2 will be moved to a new starting position together. If any PUSCH reaches the end of the time slot boundary, then the OFDM codewords beyond the time slot boundary will be punctured. Since the number of available OFDM codewords for this PUSCH is reduced, the UE can perform rate matching / puncturing of the data.

[0317] In addition, the UE moves the PUSCH to a new starting position, but the UE may keep the scheduled DMRS symbols as follows, for example. Fig.54A For example, if one or more DMRS symbols fall before the new starting position of the PUSCH, then these symbols will be discarded, as shown in the original grant. Fig.54BAs shown in . If the new starting position of the PUSCH falls outside all scheduled DMRS symbols, the UE may abandon the transmission of the PUSCH. Alternatively, as mentioned above, the UE may be configured with a specific number of compensation DMRS symbols that may be transmitted, their positions, any other configuration, etc., through, for example, higher layer signaling that the UE may transmit, and all scheduled DMRS symbols UE may be discarded. Fig.54C An example is shown where the PUSCH starting position is at OS 10, where all previous DMRS symbols are discarded. In this case, the UE can transmit a DMRS symbol in the first OFDM symbol of the PUSCH with a new starting position.

[0318] Power boost in first PUSCH transmission

[0319] For the first PUSCH transmission in a UE’s COT, the DMRS power is boosted relative to the DMRS in subsequent PUSCH transmissions within that COT. This ensures higher reliability of detecting PUSCH at the gNB and improves channel quality estimation. This in turn improves the BLER on PUSCH if PUSCH transmissions rate-match fewer resources or are punctured due to delayed channel access. This concept is discussed in Fig.35 , where the nominal power is increased in the DMRS sequence of the first PUSCH transmission of the UE after CAT4 LBT.

[0320] As another use case, if the PUSCH transmission starts at a position that causes the UE to drop one or more OSs carrying DMRS sequences, the UE may boost the power of the remaining DMRS sequences to improve the quality of the channel estimation. Fig.36 An example of a Type B PUSCH transmission is shown where OS#0 is not transmitted due to lack of channel availability. The power is boosted on the remaining DMRS symbols within the grant, somewhat compensating for the loss of the DMRS sequence in OS#0. Here, the gNB will detect the absence of DMRS on OS#0 and recognize that the PUSCH did not start on OS#0. It recognizes DMRS on OS#3 and attempts to decode the PUSCH from starting positions OS#1, 2, and 3.

[0321] Power boost value α DMRS-CAI Configured to the UE via RRC signaling. This value may depend on the number of DMRS sequences actually transmitted in the available PUSCH resources.

[0322] Furthermore, after the UE's LBT, the power used for the PUSCH REs may be boosted within the available PUSCH resources for the first PUSCH transmission within the COT of the UE. The boost may vary depending on the number of available OSs. If the original grant has N OSs and the UE can only access K OSs, then the UE may boost the power of the PUSCH REs in the K OSs by a factor P PUSCH，boost =10*log10(α PUSCH-CAI *N / K). Here, α PUSCH-CAI It is configured to the UE via RRC signaling and is a value greater than or equal to 0 and is applied to the first PUSCH after channel access. A typical setting may use a value of 1. The UE may apply power boost only if it has power headroom for a given N and K. Otherwise, it may boost power to the maximum possible value P for the device. PUSCH-CAI =max(P PUSCH，nominal +P PUSCH，boost , P max ). Here, P PUSCH-CAI is the power applied to the first PUSCH transmission after LBT, P max is the maximum power that the UE can transmit (P max It may depend on the capability of the UE and / or may be configured to the UE via RRC signaling). PUSCH，nominal is the nominal power for transmitting PUSCH transmissions. PUSCH transmissions after the first PUSCH transmission can use P PUSCH，nominal Power level.

[0323] DMRS sequence dependent on PUSCH starting position

[0324] The UE can be configured via RRC signaling with multiple DMRS sequences, where the UE selects the DMRS sequence that indicates the starting OS for the PUSCH. Fig.37 , where the UE is configured with 4 candidate starting positions - OS#0, OS#1, OS#2 and OS#3 and four corresponding DMRS sequences. When the UE has channel access to OS#0, it will transmit sequence #1 for DMRS, when the UE has channel access to OS#1, it will transmit sequence #2 for DMRS, and so on. Here, the gNB monitors all candidate DMRS sequences. After finding a valid sequence, it infers the starting position of the PUSCH transmission from the sequence. This approach avoids the need to blindly detect the starting OS for PUSCH transmission.

[0325] The sequence can be defined by providing different initialization parameters for the candidate starting positions in the pseudo-random sequence generator. For example, the parameter n can be introduced in the DMRS sequence. CAI , where n CAIVaries depending on the starting position of the PUSCH. If transform precoding for PUSCH is enabled, the reference signal sequence r(n) should be generated according to the following conditions:

[0326]

[0327]

[0328] in is a low PAPR sequence defined as follows: for PUSCH transmission dynamically scheduled by DCI, δ=1, and α=0.

[0329] According to the following formula, the basic sequence The cyclic shift α of

[0330]

[0331] in is the length of the sequence. Multiple sequences are defined from a single base sequence by different values ​​of α and δ.

[0332] basic sequence is divided into groups, where u∈{0, 1, ..., 29} is the group number and v is the base sequence number within the group, so that each group contains each length 1≤m / 2 δ ≤5 basic sequences (v=0) and each length 6≤m / 2 δ Two basic sequences (v=0, 1).

[0333] Sequence Group in Given by:

[0334] - if Configured by higher layer parameter nPUSCH-Identity-Transform-precoding and the PUSCH is not msg3 PUSCH

[0335] - Other situations

[0336] Where n CAI A parameter defined to identify the starting position of PUSCH

[0337] where f gh and the sequence number v is given by:

[0338] - If neither group hopping nor sequence hopping is used

[0339] fgh =0

[0340] v=0

[0341] - If group hopping is used instead of sequence hopping

[0342]

[0343] v=0

[0344] where the pseudo-random sequence c(i) is a pseudo-random Gold sequence of length 31 and shall be present at the beginning of each radio frame with Initialize;

[0345] - If sequence hopping should be used instead of group hopping

[0346] f gh =0

[0347]

[0348] where the pseudo-random sequence c(i) is a pseudo-random Gold sequence of length 31, whose generator shall start at the beginning of each radio frame. Initialize.

[0349] If transform precoding for PUSCH is not enabled, the sequence r(n) shall be generated according to

[0350]

[0351] The pseudo-random sequence c(i) is a pseudo-random Gold sequence of length 31, and its generator should be initialized using the following formula

[0352]

[0353] Where l is the number of OFDM symbols in a time slot, The number of time slots in a frame, and

[0354] -n SCID ∈{0, 1} and Given by the higher layer parameter UL-DMRS-Scrambling-ID (if provided), and the PUSCH is not msg3 PUSCH

[0355] -n SCID = 0 and Other situations

[0356] Where n CAI A parameter defined to identify the starting position of PUSCH

[0357] DMRS resource density in the first PUSCH transmission

[0358] The UE is RRC configured for a certain number of DMRS sequences for PUSCH transmission. According to another aspect, when the UE performs a PUSCH transmission after a successful LBT, the UE may use a different number of DMRS transmissions, i.e., the UE may use a different number of DMRS transmissions in the first PUSCH transmission of its COT. This enables the gNB to improve channel estimation and thereby improve the BLER on the PUSCH when it is punctured or rate matched to fewer resources. The DMRS configuration for PUSCH after a successful LBT may be configured by RRC signaling to the UE. As Fig.38 As seen in Figure 1, the density of DMRS is higher and the time resource of DMRS is different in the first PUSCH transmission after LBT compared to the next PUSCH transmission in the UE's COT. Here, the UE has 2 UL grants of PUSCH type B and is configured by RRC to transmit DMRS in OS#{0,3,6,9} for the first PUSCH transmission and in OS#{0,10} for subsequent PUSCH transmissions.

[0359] UL preamble to indicate variable starting position

[0360] The UE may transmit an UL preamble to indicate the starting position of the first PUSCH after the LBT. The location of the PUSCH resources relative to this preamble. For example, the PUSCH may start in the same OS as the preamble, such as Fig.39 As shown in . In this example, the preamble is transmitted on every other RE. But in general, the preamble can have any set of time / frequency resources configured to the UE. The gNB monitors and detects the preamble; when it detects it, the gNB finds the PUSCH in the same OS.

[0361] The gNB configures the spatial direction of the transmission of the preamble. For example, the preamble can have the same correspondence as the DMRS sequence of that PUSCH transmission. Alternatively, the preamble can be transmitted in a spatial direction corresponding to a different RS (such as SSB / PBCH or CSI-RS). If the preamble resource conflicts with the DMRS resource of the PUSCH, the DMRS is dropped and the preamble is transmitted.

[0362] In addition, if Fig.40 As shown in , the preamble can be narrowband relative to the bandwidth of the PUSCH so that the gNB can easily detect it. Its frequency resources can be configured relative to the PUSCH resources in the grant, such as with Fig.40 The offset of the lowest RB of PUSCH as shown in A, or as Fig.40 The center shown in B is fixed relative to the carrier.

[0363] The preamble sequence is configured to the UE via RRC signaling. The sequence can be UE-specific or commonly configured across UEs.

[0364] When the UE is specially configured, the preamble may have the same sequence as the DMRS of the PUSCH. The preamble may be applied only to the frequency resources of the PUSCH.

[0365] The preamble may be transmitted corresponding to a DL RS such as an SSB or a CSI-RS or a DMRS. For example, the preamble may have the same corresponding relationship as the DMRS of the PUSCH following the preamble. Alternatively, the corresponding relationship may be configured through RRC signaling to the UE.

[0366] In addition to indicating the start of a PUSCH transmission, the preamble may also be used to indicate the duration of the UE's COT. A set of preambles may be configured to the UE. Each preamble may represent a certain duration of the COT. The UE may select the preamble to transmit based on its expected channel occupancy duration. For example, in autonomous UL transmissions using configured grants, the gNB may not know how to expect PUSCH transmissions from the UE without higher layer information such as the BSR. To reduce latency, PHY signaling through the preamble may indicate the duration of the configured granted resource usage. This can help the gNB plan its resources after the UE's COT, or enable efficient COT sharing between the UE and the gNB.

[0367] If the preamble sequence is common to multiple UEs, the preamble can provide improved power efficiency and coexistence because other nodes can recognize that the channel is occupied. If the preamble is common in DL and UL, this promotes coexistence. The location of the preamble resources can be common in DL and UL. The PUSCH can be rate matched near the preamble, or the preamble can be punctured for PUSCH.

[0368] For PUSCH mapping type B for either SU-MIMO or MU-MIMO, the position of the DMRS symbols is defined relative to the PUSCH resources. Therefore, if the UE selects a PUSCH starting position that is different from the originally scheduled position, the UE may transmit (one or more) UL DMRS symbols according to PUSCH type B. In this case, the first DMRS symbol may occupy the first symbol of the PUSCH with the UE-selected starting position. According to the PUSCH type B DMRS mapping rules, the position and number of additional DMRS symbols may be based on the duration of the PUSCH with the UE-selected position. For example, Fig.49 An example of a PUSCH is shown, which is scheduled for transmission over 8 OFDM symbols from OS 5 to OS 12 with two additional ULDMRS symbols, but the UE fails to access the channel due to LBT failure. If the channel becomes available starting from the candidate position shown in the figure (i.e., OS 7), the duration of the PUSCH with the starting position selected by the UE is 6 OFDM symbols. In this case, Fig.49 As shown in , the UE can map the UL DMRS according to 6 OS and a new PUSCH duration of 4 relative to the start of PUSCH in l0 following mapping type B.

[0369] Transmit PUSCH in available symbols

[0370] Some procedures are described above so that the gNB and UE have the same understanding of which starting position the UE can try to access the channel in the event that the UE cannot access the channel at the start of the UL grant. Several methods are also described on how to affect the DMRS by shifting the starting position and how it can be used to indicate which PUSCH candidate position the UE selects. In the following, procedures for puncturing, adapting the MCS, and how to transmit the piggybacked UCI are described.

[0371] Deletion

[0372] As a simple process, after the UE generates PUSCH based on the grant provided by the gNB, the UE can puncture some of those symbols and transmit other symbols without adjusting the ULDMRS position. According to one aspect, the UE can puncture all symbols from the start of the PUSCH grant to the symbol from which the user accesses the channel. Fig.41 An example of a PUSCH grant equal to a duration of 12 symbols from OS 0 to OS 11 is shown, where three additional DMRS are configured to occupy 10, 5, 8, 11. If the UE accesses the channel starting from OS7, the UE may puncture OS0 to OS6.

[0373] In some cases, the remaining DMRS may not be sufficient for the gNB to obtain accurate channel estimates, especially if all DMRS symbols are punctured, since the last two OFDM symbols in the PUSCH may not carry DMRS at all. Therefore, according to another aspect, a minimum number of required DMRS symbols may be transmitted to obtain reliable decoding at the gNB. If the remaining DMRS symbols are less than this minimum threshold, the UE may abandon UL transmission to reduce power consumption, since the gNB is unlikely to decode the transmitted PUSCH.

[0374] This threshold may be configured by a higher layer parameter such as an RRC parameter called min_DMRS_num, which may provide an absolute number of the minimum number of required DMRS symbols or a fraction of the already scheduled DMRS symbols. Furthermore, the minimum number of required DMRS symbols may depend on the scheduled PUSCH grant parameters such as MCS and PUSCH duration. Table 6 shows an example of the minimum number of required DMRS symbols as a function of the scheduled MCS, where MCS is the MCS for a given DCI providing a PUSCH grant. Also, the MCS for i∈{1,…,N} may be provided by a higher layer parameter such as the RRC parameter min_DMRS_num th_i If the higher layer parameters indicate that the MCS thresholds in any row are equal, that is, the MCS th_(i-1) =MCS th_i , then the minimum number of required DMRS symbols for the associated rows where both MCS thresholds appear are disabled.

[0375] Table 6 Minimum number of required DMRS symbols depending on MCS

[0376]

[0377] Similarly, the minimum number of required DMRS symbols may vary according to the PUSCH duration as shown in Table 7, for example, where L is the actual number of OFDM symbols that may be transmitted, and D for i∈{1,…,N} th_i It may be provided by a higher layer parameter such as the RRC parameter min_DMRS_num. If the higher layer parameter indicates that the PUSCH duration thresholds in any row are equal, that is, D th_(i-1) =D th_i , then the minimum number of required DMRS symbols for the associated rows where both MCS thresholds appear are disabled.

[0378] Table 7 Minimum number of required DMRS symbols depending on the actual number of OFDM symbols that can be transmitted by the UE

[0379]

[0380] Also, puncturing may be used in case of MU-MIMO scheduling to avoid loss of orthogonality between co-scheduled UEs.The UE may only use any scheduled DMRS symbols and may not attempt to adjust the UL DMRS based on the duration of the PUSCH with the newly selected starting position.

[0381] Adapt MCS

[0382] Assuming that the granted TBS size is fixed and does not depend on the LBT result, the MCS associated with the scheduled PUSCH may not be a valid MCS for transmitting the entire TBS in one transmission. At the same time, if the UE autonomously changes the MCS associated with the scheduled PUSCH chain based on the LBT result without common knowledge of the new MCS between the UE and the gNB, it will be a huge burden for the gNB to detect the used MCS.

[0383] If multiple PUSCH starting positions are signaled via multiple DCIs, as described previously, then the correct MCS associated with the new PUSCH starting position may be signaled in these DCIs.

[0384] If multiple PUSCH starting positions are configured by higher layer parameters, the new MCS can be determined to vary according to several parameters provided by the PUSCH grant. For example, the new MCS can depend on the PUSCH grant, such as PUSCH duration, MCS, etc., and the duration of the PUSCH with the starting position selected by the UE based on the LBT result, as shown in Table 8:

[0385] Table 8 New MCS according to the old MCS and LBT results

[0386]

[0387] Where L is the duration of the PUSCH provided in the UL grant in terms of symbols, and I MCS is the MCS given in the PUSCH grant. new,N(L-1) According to I MCS For example, I new,x =max{2 I MCS ,MCS_max} means that the new MCS is twice the MCS given in the PUSCH grant and has a certain maximum MCS labeled MCS_max.

[0388] Alternatively, the UE can autonomously change the MCS by transmitting piggybacked UCI to the PUSCH and indicating the selected MCS. Moreover, the piggybacked UCI can be transmitted in a specified position in the new PUSCH duration. For example, the piggybacked UCI can be transmitted after the first DMRS symbol so that the gNB first decodes the UCI to know the MCS selected by the UE and then decodes the data portion in the PUSCH.

[0389] Instead of transmitting UCI to carry the selected MCS, the UL DMRS can indicate the selected MCS. For example, several initialization sequences can be provided to the UE and they have a one-to-one mapping with the candidate MCSs. Therefore, the gNB can find out the selected MCS by knowing the DMRS initialization sequence. This can be done by signaling multiple values ​​for generating the DMRS initialization sequence by the following equation to achieve.

[0390]

[0391] The additional value of may be given by higher layer parameters such as the RRC parameter scrambling_to_MCS_mapping, and the other parameters in the above equation are defined earlier. The gNB needs to blindly detect the DM-RS and the corresponding initialization to detect the MCS.

[0392] UCI transmission

[0393] If PUSCH symbols are punctured or shifted based on LBT results, the piggybacked UCI may be affected, especially if UCI is mapped to the first few OFDM symbols at the beginning of the PUSCH grant. According to another aspect, if UCI does not carry DMRS or is immediately after the first single-symbol / double-symbol DMRS transmission, then UCI may have a higher priority than PUSCH and may be transmitted in the first available symbol.

[0394] Because only a few OFDM symbols are available for UL transmission based on the LBT results, there may not be enough resources to carry UCI, especially if its size is large. Therefore, according to another aspect, specific priority rules can be defined to define which content of UCI can be discarded. For example:

[0395] ● The priority of the Part 2 CSI report may be lower than that of the Part 1 CSI report.

[0396] ●Part 2 CSI reports may have a lower priority than Ack / Nack feedback.

[0397] ●Part 1 CSI reports may have a lower priority than Ack / Nack feedback.

[0398] Since the content of UCI can vary according to the LBT result, blind decoding of different UCI with different contents by the gNB can be a burden. Thus, according to another aspect, UL DMRS can indicate the content of the carried UCI. For example, if the UCI content is divided into three categories, i.e., the 2nd part CSI report < the 1st part CSI report < Ack / Nack feedback, then the possible DMRS initialization sequences can be divided into three groups, where each group of initialization sequences corresponds to a specific UCI category.

[0399] Signaling the CAI

[0400] The CAI can be signaled as a whole as a PHY signal, especially in cases where latency is important and other general nodes should be able to read it. In scenarios where latency is not an issue, it can also be sent via higher layer signaling.

[0401] PHY signaling of the CAI

[0402] Signaling via PDCCH in the common search space

[0403] In DL, NR DCI can carry a payload, and PDCCH can be used to signal the CAI in the physical layer.

[0404] The aim is to enable sibling nodes and general nodes (at least from other NR-U cells) to detect the CAI transmitted by nodes in the cell. The PDCCH can be scrambled with the DL-CAI-RNTI that can be provided by the specification to make it common among NR-U cells; thus, general nodes know the CAI-RNTI and do not need to obtain the RMSI of the cell to acquire its CAI-RNTI.

[0405] If the NR-U cell is in DC or SA deployment, then the cell can signal the PBCH and RMSI. The DL CAI can be transmitted in CORESET with index 0 and in the common search space. Other gNBs in the NR-U band can periodically detect the presence of each other and signal to their UEs to monitor the CAI of those cell IDs. The gNB can also provide synchronization information to its UEs, thus not requiring general nodes to perform synchronization with other cells. Therefore, sibling nodes and general nodes can know the presence and location of the PBCH of coexisting NR-U cells. The cell occupying the channel can transmit the CAI in CORESET index 0. Sibling nodes and general nodes can know the CORESET to detect the CAI. Fig.14 The method of detecting the CAI is described herein. Here, gNB2 and its UE are general nodes, and gNB1 transmits the CAI on Cell1.

[0406] In a NR-U cell that performs carrier aggregation with a licensed PCell, the PCell can configure a CORESET for sibling nodes to monitor DL-CAI-RNTIDCI on the NR-U cell. Alternatively, SSB / RMSI signals can be present in the SCell to allow general nodes to monitor CAI.

[0407] A Type0B-PDCCH common search may be introduced for a DAI format having a CRC scrambled by the DL-CAI-RNTI for the CAI. The association between the monitoring timing for the Type0B-PDCCH common search space and the SS / PBCH block index may be the same as the association for the monitoring timing for the Type0-PDCCH common search space. The UE may assume that the DM-RS antenna ports associated with PDCCH reception in the Type0B-PDCCH common search space and the DM-RS antenna ports associated with SS / PBCH reception are quasi-co-located with respect to delay spread, Doppler spread, Doppler shift, average delay, and spatial Rx parameters. The values ​​used for DM-RS scrambling sequence initialization may be set as follows.

[0408] ● It can be set to a fixed constant defined by the specification

[0409] ●It can be set as the cell ID.

[0410] The length of the DCI based on the DL-CAI-RNTI may be defined in the specification or configured in the RMSI. If the number of DCI lengths monitored within CORESET Index 0 in a monitoring occasion exceeds the maximum limit in NR, the NR-U UE may discard monitoring this DCI.

[0411] A higher layer parameter dlCAIPeriod may be defined to indicate the periodicity of signaling CAI (eg Fig.10 and Fig.11 As seen in , the gNB in ​​MCOT can signal the CAI multiple times through the CNB so that the listening nodes will not miss the signal).

[0412] Not all cells may support the transmission of CAI. One bit in the PBCH may indicate whether a cell supports CAI transmission.

[0413] Alternatively, the CAI may be multicast to a group of UEs. For example, a group common PDCCH (such as a PDCCH for DCI format 2_0) may be used to carry the CAI. UEs in an RRC connected state may decode the PDCCH because they will have a configuration of the GC-CAI-RNTI for the CAI. The DCI may be scrambled with the group common RNTI "GC-CAI-RNTI".

[0414] It is advantageous for a node such as a gNB to indicate the start of channel access to a UE. This enables the UE to identify the presence of valid CSI-RS, DRS, SSB / PBCH, PRACH opportunities and / or resources for COT sharing with the gNB (configured granted resources).

[0415] The gNB may transmit a DCI with a DL-CAI-RNTI to the UE to provide the COT status. The DCI may carry at most C bits, indicating the COT of the gNB. C may be configured to the UE via RRC signaling or predefined in the specification. For example, for a MCOT of up to 10 ms, C=4. The DCI may also carry the bandwidth over which the COT is valid, for example, a bitmap of B bits corresponding to B 20 MHz subbands in the spectrum. The bit corresponding to the set of 20 MHz subbands where the gNB can access the channel is set to 1. In this case, if the UE receives a DCI with a DL-CAI-RNTI and an SFI-RNTI, it may ignore the SFI for time slots where the CAI-RNTI indicates no channel access. Alternatively, the DCI may indicate the COT by specifying a slot format for N time slots of the COT. The DL-CAI-RNTI may be an SFI-RNTI that provides a slot format indication to the UE. In addition to the "D", "X" and "U" states in the slot format for identifying the DL, flexible and UL states, respectively, a "null" format can be introduced to identify invalid channel access. For example, the slot format "NNNNNNNNNNNNNN" implies that channel access is not available on any of the 14 symbols of the slot. Slot formats with partial channel access can also be defined, such as "XXXXXXXNNNNNNN", where channel access is not available on the last 7 symbols of the slot because it is outside the COT of the node. Since the DCI can carry slot formats for multiple slots, when the codeword encounters a null format, the UE recognizes that the gNB does not have channel access rights and can ignore the SFI of the codeword after the null value. A second DCI with a BW-RNTI (Bandwidth-RNTI) can carry information on the 20MHz subband on which the COT is valid. The BW-RNTI can be detected in the same CORESET and monitoring occasions as the SFI-RNTI; therefore, the UE uses the SFI-RNTI and the BW-RNTI to determine the bandwidth and time of the gNB's channel access. In the case of directional LBT, the COT may be different in different spatial directions. In this case, a single DCI may provide COT information for multiple spatial directions. Therefore, the DCI may carry a TCI state for each COT it indicates. Alternatively, the DCI may carry the COT for D spatial directions configured to the UE. D may be provided via RMSI or OSI or configured in a UE-specific manner. Alternatively, the DCI received in a given spatial direction may indicate the COT in that spatial direction - this RS that determines the direction of channel access is called the channel access RS (CA-RS). For example, the spatial direction of a DMRS of a DCI (carrying the COT) may indicate the COT in that spatial direction; here, the CA-RS is the DMRS of the DCI that carries the COT information.Therefore, the gNB can transmit multiple DCIs to indicate the COT in different spatial directions using different CA-RS.

[0416] If the gNB has channel access rights for a given CA-RS, then a CA-RS-group may be defined as a set of RSes that may be transmitted by the gNB. For example, a CA-RS-group may be defined for a DMRS that carries a DCI for COT and includes other RSs, such as CSI-RS, that may be transmitted by the gNB in ​​similar spatial directions as the DMRS. If the UE has a grant or RS that belongs to a CA-RS-Group to which the gNB can access the channel, then the UE processes the grant or RS. The gNB may perform spatial LBT in the direction given by the CA-RS. If successful, then the gNB may transmit the signals in the CA-RS-Group for that CA-RS. A CA-RS-Group shall contain RSs with the same / similar spatial directions as the reference CA-RS in that CA-RS-group. As Fig.42 As shown in , the gNB transmits DCI carrying COT information on CA-RS1. When the UE receives this message, the UE recognizes that it can only receive signals in the spatial directions given by the RSes in the CA-RS-group of CA-RS1 in that COT.

[0417] In addition, for directional LBT, if the gNB shares its COT with the UE, the UE may perform a configured grant transmission on the shared COT only if the spatial direction of the configured grant corresponds to the DL spatial direction used for that COT. The UE may also perform CAT2 LBT to access a channel in the shared COT in the direction corresponding to the corresponding DL CA-RS. Fig.43 As shown in , the UE transmits in the COT of the gNB using the spatial direction corresponding to the DL CA-RS-Group for CA-RS1.

[0418] If a node such as a gNB acquires channel access from the beginning of a partial slot, it may only have channel access to the partial slots at the end of the COT. In this case, it cannot indicate the format of the last partial slot, as this requires additional bits to indicate the COT with finer granularity. Unless the UE has an explicit grant in the last partial slot, it cannot know the COT of the gNB in ​​the last partial slot. Therefore, for the last partial slot, even if no COT indication of valid channel access is received, if the UE has a grant, the UE assumes that the channel access is valid and continues processing that slot. If a grant is received during that COT, it can be used in particular for scheduled grants. However, for configured grants, if no COT indication of valid channel access is received for a partial slot, the UE assumes that the channel access is invalid and does not transmit in that slot.

[0419] The UE may monitor CAI only on selected resources to maintain low power consumption during the CAI monitoring duration. For example, the UE may monitor CAI periodically S CAI The CAI is monitored on the CORESET in the narrow BWP in the search space. After receiving the CAI, the UE may switch to the pre-configured wider BWP and monitor the configured CORESET for control information.

[0420] As an alternative, the UE may monitor its CAI and control information after receiving the CAI on the common BWP, but different search spaces may be configured to monitor the CAI and other control information.

[0421] Alternatively, the search space configured for a CAI is automatically disabled upon detection of the CAI for the remaining duration of the COT detected from that CAI.

[0422] Handshake is triggered by signaling via PDCCH

[0423] In the DL, the NR DCI can carry a payload for CAI-1 to be used to trigger the handshake on the UL. This can happen in the following way.

[0424] ● The PDCCH for CAI-1 can be signaled using C-RNTI or CS-RNTI. The UE blindly decodes the PDCCH and responds with CAI-R if its LBT is successful. CAI-I can also indicate the type of LBT that the UE must perform before sending CAI-R. This method is Fig.15 In this case, other UEs attached to the same cell and nodes outside the cell cannot receive CAI-1.

[0425] The trigger may be sent as part of a DL or UL grant in a UE-specific search space or in a Type0-PDCCH common search space. A new DCI format 1_1C, 1_0C, 0_1C, 0_0C may be introduced with one or more of the following fields.

[0426] ○1 bit, indicating that a handshake is required

[0427] ○L bit, indicating the type of LBT to be performed by the UE, the priority class

[0428] ○D position is used for T OCC , indicating the channel occupancy time so that the UE can use the T OCC The internal signal notifies its CAI-R.

[0429] ○H bit, indicating the threshold used for sensing before CAI-R transmission

[0430] The PDCCH for CAI-1 can be signaled in a search space such as the Type 0 common PDCCH search space with CAI-RNTI in a common search space. The CAI-RNTI can be configured by RMSI or a constant value given in the specification. Multiple sibling nodes can receive DCI, and one or more UEs can send their CAI-Rs depending on how the CAI-I configures the trigger. Universal nodes from other NR-U cells can also detect CAI-1 and obtain T OCC . The DCI may also have an L bit to indicate the type of LBT to be performed by the triggered UE. The CAI-R shall contain the implicit or explicit identity of the receiver so that the receiver can identify the sender of the CAI-R. The CAI-R may also contain the identity of the node requesting the handshake – this may be useful in D2D or V2X applications where multiple nodes may access resources via frequency / time multiplexing; therefore multiple CAI-Is and CAI-Rs may be transmitted and their senders and receivers should be identifiable. The trigger may be provided in the following way.

[0431] ● Reception of CAII-RNTI implicitly triggers the handshake. Triggering time T from reception of CAI-I Resp The UE that receives DL or UL authorization transmits CAI-R. Fig.16 As shown in FIG, UE1 is at time T of CAI-1. Resp Therefore, if UE1's CCA / LBT is successful, it will respond with CAI-R.

[0432] ●Similar to P-RNTI, CAII-RNTI can provide a PDSCH grant that carries the ID of the UE that must respond with a CAI-R (such as C-RNTI). The UE whose ID is found in the message sends the CAI-R. This approach causes some inherent latency since the message must be processed by higher layers.

[0433] ● CAII-RNTI itself can carry the ID of the triggered UE. After receiving its ID in CAI-1, the UE transmits CAI-R. However, this approach makes the payload in DCI huge.

[0434] Signaling of CAI-R via RACH

[0435] The CAI-R response cannot carry much information other than indicating that the channel is clear for reception for this node. Therefore the PRACH preamble is a good candidate for CAI-R. The RACH preamble for CAI-R can be configured to the UE by the RRC. Contention-free RACH resources are preferred to ensure that all CAI-R signals are received at the gNB without collision. Due to the orthogonal nature of the PRACH preambles, multiple CAI-Rs can be received simultaneously. After the preamble reception, the handshake is completed and the gNB proceeds with DL / UL grants to the UE.

[0436] Signaling UL CAI-R on PUCCH

[0437] The short PUCCH format used for SR can be used for CAI-R. When the gNB detects energy in the UE's CAI-R resources, it assumes that the CAI-R has been received and the handshake is complete.

[0438] CAI-R may include additional information such as the energy level detected during CCA / LBT at the UE. In addition, it may carry energy levels for multiple beams (corresponding to DL RS or QCL with UL SRS). In this case, the payload is too large to be indicated by RACH. Short PUCCH or long PUCCH may be used for CAI-R.

[0439] CAI-R from multiple UEs may be orthogonally multiplexed or multiplexed with other PUCCH signals from other UEs.

[0440] Preamble-Assisted CAI

[0441] The preamble can be used to indicate CAI. It can carry the indication T OCCOr some or all of the information needed by the cell using the channel. In addition, it can indicate resources where more information about occupancy can be obtained. Such a design can make it simple for nodes from other cells and technologies to detect the preamble without having to obtain SI from the NR-U node occupying the channel. The node monitors the preamble over time and looks for a high correlation with a known preamble. When the correlation exceeds a threshold, the preamble is detected.

[0442] A common preamble can be used across all NR-U nodes to make detection of common nodes simple. The preamble can be a ZC sequence on the DL or an m-sequence based (such as PSS or SSS) or an RS-sequence based (such as CQI-RS). On the UL, it can be a PRACH or SRS-like sequence.

[0443] Cell Coloring

[0444] The preamble may carry S bits of information indicating the cell in which the CAI is transmitted. The S bits may be derived from the cell ID of the gNB or UE connected to that cell ID. If S is small (example 2 or 3 bits), then the listening node needs to correlate with a known sequence of a small set of possible preambles (4 or 8 for 2 or 3 bits). The S bits provide “cell coloring” that enables the listening node to identify whether the transmission is within or outside its cell. If the number of bits indicated is less than the number of cell IDs, then there is some ambiguity in identifying the cell in which the preamble is transmitted; therefore, a general node cannot know if it is from its own cell, but it can quickly identify CAI from many cells. To resolve the ambiguity, other information may be included in the preamble, but a node that identifies the transmission as being from a different cell does not need to look up this information. The method for detecting the preamble is described in Fig.17 If complete information about the cell ID is available, then nodes within the cell can use a higher threshold for LBT failure and allow spatial multiplexing.

[0445] Indicate T on the preamble OCC

[0446] The S bit of the preamble can be used to indicate T OCC The general nodes will know the state of the channel and when they should start sensing the channel.

[0447] Indicates the S bit on the preamble

[0448] The S bit can be indicated in one of the following ways. Generally speaking, if the preamble has the ability to indicate the S bit, then the S bit can be indicated in the T OCC With the split between cell coloring.

[0449] ● For ZC-based preambles, the S bits can be used as a root or part of a cyclic shift

[0450] • The S bit can be used as part of the initialization for the m-sequence based preamble.

[0451] ●Preamble sequence p It can be repeated S times in time; the OCC vector of length S can be w is applied to S repetitions to carry S bits of information. Here, the preamble is repeated 4 times and <h2 style=";text-align:left;direction:ltr">w = [w0 w1 w2 w3]<h2 style=";text-align:left;direction:ltr"> T .

[0452] Fig.18 (A) shows an example of how the preamble is transmitted repeatedly in time. The preamble can be transmitted asynchronously – so Node1 transmits it immediately after successfully completing the LBT. After transmitting the preamble, it can transmit some reserved signal to synchronize with the symbol boundaries.

[0453] Fig.18 (B) shows an example of transmitting a preamble synchronously with a symbol boundary. A successful LBT is followed by a reservation signal. After the start symbol boundary, the preamble is transmitted.

[0454] Preamble Resources

[0455] The CAI preamble can be narrowband so that the receiving node can detect it with minimal power consumption. Its bandwidth can be less than the minimum BWP supported in NR-U, such as 5MHz for FR1. Since the ETSI harmonized standards for 5GHz require the use of 20MHz channels, but also allow operation in smaller bands (as small as 5MHz) centered around the 20MHz band, the choice of 5MHz for the CAI preamble can be good for coexistence with WiFi. If the preamble meets the minimum OCB requirement, i.e., 80% of 5MHz, then it may be sufficient.

[0456] The preamble may be transmitted at a predefined location in an unlicensed band, such as the center of a 20 MHz band, or in a specific predefined location, such as a raster location, so that a general purpose node can identify its location. Fig.19 An example is shown in , where an 80 MHz band is channelized into a 20 MHz band and a CAI preamble may be transmitted at the center 5 MHz.

[0457] The resources of CAI can be configured through RRC and indicated through SI so that all UEs can locate CAI. In CA, the information can be provided by PCell. In DC, the information can be provided by MCG or obtained from SI carried in DRS or SSB. In SA, this information can also be obtained from SI carried in DRS or SSB. SI can provide frequency resources as an offset from the lowest PRB of CBW.

[0458] Since NR supports operation in wider bandwidths, NR-U nodes can use multiple 20MHz bands to create a composite carrier of larger bandwidth in a single cell. (Instead of carrier aggregation, which aggregates many SCells together, many bandwidth blocks are combined into a cell.) In this case, this paper also proposes to transmit the preamble at the center of each 20MHz subband of the aggregated band. Fig. 20 As shown in , an 80 MHz band consisting of four 20 MHz channels is used in the unlicensed spectrum. The NR-U node uses three 20 MHz channels to form a 60 MHz composite channel. According to another aspect, a CAI preamble code can be sent at the center of each 20 MHz channel so that a universal node in each 20 MHz channel can detect the state of the channel without having to switch frequencies.

[0459] Alternatively, the gNB may provide a bitmap in the SI or dynamically (via grant, in particular when handshaking is triggered) to indicate which 20 MHz band carries the CAI.

[0460] The numerology of the preamble can be determined as follows:

[0461] ● The preamble uses predefined numerology based on the frequency band. For example, 15KHz for FR1 enables UEs with different processing capabilities to receive this signal. 30KHz and 60KHz can also be used as this keeps the delay due to the CAI preamble small and allows more repetitions with cover codes.

[0462] The preamble uses the same numerology as SSB. In this case, the listening node is required to know the numerology used for the SSB or NR-U cell, either by performing an initial access or by configuration from the PCell or PSCell.

[0463] Generally speaking, the information that can be sent on the preamble is limited. Therefore, this paper proposes that the preamble be used in conjunction with other forms of transmitting CAI (such as PDCCH, RACH, and RS). The preamble can indicate the time and resources where the remaining information of the CAI can be received. In other words, if the preamble information is relevant to the node, then the node will wake up to find the remaining CAI information, such as Fig.17 The remaining information of CAI can appear in the first opportunity (of the signal type) after the preamble, or in the first N opportunities after the preamble. For example, if the remaining information is transmitted on the PDCCH, the node can look for this information in the first monitoring opportunity after the preamble. This concept is discussed in Fig.44As shown in FIG, the UE monitors the DL signal to obtain the preamble. After finding the preamble, it will decode the DCI carrying the COT information in its PDCCH monitoring opportunity.

[0464] Another example is Fig.45 , where the CORESET and monitoring opportunities are preconfigured immediately after the preamble to save resources. If there are multiple symbols between the preamble and the next monitoring opportunity, the gNB cannot indicate the COT information or perform scheduling for the UE immediately, and resources may be wasted. Instead, the CORESET and search space monitoring opportunities may be provided after the preamble with minimal latency. This control resource may be aperiodic, i.e., its presence is defined by the position of the preamble.

[0465] Aperiodic CORESET / search space monitoring timing can be combined with Fig.46 The preamble shown is in the same OS. This allows better resource utilization as it reduces the latency between the preamble and the DCI.

[0466] The preamble and DMRS of the DCI carrying COT information can be QCL signals. Therefore, when the UE receives a preamble in a certain spatial direction, it expects to also receive the aperiodic CORESET in that direction, i.e., the aperiodic CORESET has the same QCL as the preamble. The gNB transmits the preamble multiple times in different spatial directions, such as Fig.47 to cover all UEs. The aperiodic CORESET is configured via RRC signaling. The monitoring opportunities associated with this CORESET are defined as aperiodic, for example, the search space monitoring opportunity only occurs once in relation to the detected preamble. This search space is configured to the UE via RRC signaling and the parameter monitoringSlotPeriodicityAndOffset may not be set because the offset is determined by the preamble and it is not periodic.

[0467] In addition, the preamble can be in the form of DMRS of PDCCH in CORESET. The gNB can schedule the preamble in the form of wideband DMRS so that it provides sufficient reliability.

[0468] It should be understood that any or all of the devices, systems, methods, and processes described herein may be implemented in the form of computer-executable instructions (e.g., program codes) stored on a computer-readable storage medium, which are executed by a processor (e.g., Fig. 21B and 21FThe processor 118 or 91) of the computer system is executed and / or implements the system, method and processing described herein. Specifically, any step, operation or function described herein can be implemented in the form of such computer executable instructions executed on a processor of a device or computing system configured for wireless and / or wired network communication. Computer-readable storage media include volatile and non-volatile, removable and non-removable media implemented by any non-transient (e.g., tangible or physical) method or technology for storing information, but such computer-readable storage media do not include signals. Computer-readable storage media include, but are not limited to, RAM, ROM, EEPROM, flash memory or other memory technology, CD-ROM, digital versatile disk (DVD) or other optical disk storage device, cassette, tape, disk storage or other magnetic storage device, or any other tangible or physical medium that can be used to store desired information and can be accessed by a computing system.

[0469] In describing the preferred embodiments of the subject matter of the present disclosure, as shown in the figures, specific terminology is employed for clarity. However, the claimed subject matter is not intended to be limited to the specific terminology so selected, and it should be understood that each specific element includes all technical equivalents that operate in a similar manner to achieve a similar purpose.

[0470] This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any device or system and performing any combined methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. If such other examples have elements that do not differ from the literal language of the claims, or if they include equivalent elements that do not differ substantially from the literal language of the claims, then they are intended to be within the scope of the claims.

Claims

1. An apparatus comprising a processor, a memory, and a communication circuit system, wherein the processor, the memory, and the communication circuit system are configured to: receiving a radio resource control RRC message, the RRC message comprising an indication of the number of bits for indicating a channel occupancy time COT in downlink control information DCI transmission; receiving a first DCI, wherein the first DCI is associated with a slot format indicator radio network temporary identifier SFI-RNTI, and the first DCI comprises a slot format indication, an indication of a COT using a number of bits indicated in an RRC message, and a bitmap indicating one or more available subbands; wherein the bitmap comprises a plurality of bits, wherein each bit of the plurality of bits corresponds to a 20 MHz subband, wherein a bit in the plurality of bits is set to 1 to indicate that the corresponding 20 MHz sub-band has channel access, wherein the first DCI indicates that channel access is partially available for a first time slot, and wherein the first DCI includes an indication that channel access is available on one or more first symbols of a first time slot; determining the COT from the first DCI; receiving a second DCI, wherein the second DCI is associated with a cell radio network temporary identifier (C-RNTI), the second DCI comprises an uplink grant, and the uplink grant indicates a plurality of time domain resource assignments; as well as A physical uplink shared channel transmission is performed according to at least one of the plurality of time-domain resource assignments during at least a portion of the COT.

2. The apparatus of claim 1, wherein the first DCI comprises an indication that the channel access is unavailable on one or more second symbols of the first time slot. The apparatus of claim 1 , wherein the first DCI is a multicast DCI.

4. An apparatus comprising a processor, a memory, and a communication circuit system, wherein the processor, the memory, and the communication circuit system are configured to: Sending a radio resource control RRC message, wherein the RRC message includes an indication of the number of bits of a channel occupancy time COT in downlink control information DCI transmission; sending a first DCI to a wireless transmit receive unit (WTRU), wherein the first DCI is associated with a slot format indicator radio network temporary identifier SFI-RNTI and the first DCI includes a slot format indication, an indication of a COT using a number of bits indicated in an RRC message, and a bitmap indicating one or more available subbands; wherein the bitmap comprises a plurality of bits, wherein each bit of the plurality of bits corresponds to a 20 MHz subband, wherein a bit in the plurality of bits is set to 1 to indicate that the corresponding 20 MHz sub-band has channel access, wherein the first DCI indicates that channel access is partially available for a first time slot, and wherein the first DCI includes an indication that channel access is available on one or more first symbols of a first time slot; sending a second DCI to the WTRU, wherein the second DCI is associated with a cell radio network temporary identifier (C-RNTI), the second DCI includes an uplink grant, and the uplink grant indicates a plurality of time domain resource assignments; and A physical uplink shared channel transmission is received from the WTRU according to at least one of the plurality of time-domain resource assignments during at least a portion of the COT. The apparatus of claim 4 , wherein the first DCI is a multicast DCI.

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