Channel access indication for spectrum reuse, power saving and coexistence

Abstract

The invention relates to channel access indication for spectrum reuse, power saving, and coexistence. A channel access indicator (CAI) may be employed in a new radio unlicensed (NR-U) to indicate a node's channel occupancy to its off-cell nodes, to indicate a node's channel occupancy to its intra-cell nodes, to facilitate spectrum reuse, and to trigger handshake between intra-cell nodes to ensure that a receiver has a smooth channel for transmission and reception.

Description

[0001] This application is a divisional application of the patent application for "Channel Access Indication for Spectrum Reuse, Power Saving, and Coexistence" with the application date of May 10, 2019, application number 201980031372.1, and invention name. Background Art

[0002] LTE Licensed-Assisted Access

[0003] Carrier aggregation with at least one SCell operating in unlicensed spectrum is referred to as Licensed-Assisted Access (LAA). Thus, 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 referred to as an LAA SCell. Unless otherwise stated, the 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.

[0004] The LAA eNB and UE apply Listen Before Talk (LBT) before performing transmission on the LAA SCell. LBT is a method by which a radio transmitter first senses the medium and only transmits when the medium is sensed to be idle, which is also referred to as Clear Channel Assessment (CCA). When applying LBT, the transmitter listens / senses the channel to determine whether the channel is idle or busy. If the channel is determined to be idle, then the transmitter can perform transmission; otherwise, it does not perform transmission. If the LAA eNB uses the channel access signal of other technologies for LAA channel access, then it should continue to meet the LAA maximum energy detection threshold requirement.

[0005] There are various LBT methods, but one recommended by 3GPP is called LBT Load-Based Category 4. This adds a WiFi-like random access protocol to not only ensure LTE / WiFi coexistence but also provide 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 respectively for both downlink (DL) and uplink (UL) transmissions. The main channel access procedures are described in Section 15 of 3GPP TS 36.213, Physical layer procedures (Release 15), V15.0.0.

[0006] LTE Frame Structure Type 3

[0007] Frame structure type 3 is only applicable to LAA secondary cell operation with normal cyclic prefix. Each radio frame T f = 307200·T s = 10 ms long and consists of 20 time slots of length T slot = 15360·T s = 0.5 ms, numbered from 0 to 19. A subframe is defined as two consecutive time slots, where subframe i consists of time slots i and 2i + 1.

[0008] Ten 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 either when the last subframe is fully occupied or following one of the DwPTS durations specified in Table 4.2-1 of 3GPP TS 36.213, Physical layer procedures (Release 15), V15.0.0. Uplink transmission occupies one or more consecutive subframes.

[0009] Next-generation network requirements

[0010] 3GPP TR 38.913, Study on Scenarios and Requirements for NextGeneration 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.

[0011] Table 1: KPIs for eMBB, URLLC, and mMTC devices

[0012]

[0013]

[0014]

[0015] Receiver-assisted unlicensed operation

[0016] To coordinate spectrum access among technologies in a distributed and simple manner, a transmitter must first detect the energy across the intended transmission frequency band. This energy detection (ED) mechanism notifies 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 scenarios. For example, when the information is encoded to be received below the background noise level, or when nodes are far apart and the signal at the receiver is weak. Thus, a node wishing to transmit may 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.

[0017] Nonetheless, 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 of false detections due to noise. Therefore, additional information is needed for efficient inter-technology and intra-technology wireless medium access.

[0018] The RTS / CTS mechanism in WiFi

[0019] The 802.11 media access control (MAC) protocol augments the ED mechanism with a virtual carrier sense (VCS) mechanism so that 802.11 packet headers can be received and decoded at the lowest power level due to the use of the most robust modulation and coding. 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 in use, is updated based on the content of such headers or control packets. For example, the request-to-send / clear-to-send (RTS / CTS) mechanism reserves the channel by having all nodes around the receiving transmitter and the receiver update their NAVs upon receiving the RTS and CTS respectively. However, even with VCS, there are problems as the capture effect, which causes stronger overlapping packets to be captured preferentially over weaker ones, leads to unfairness as stronger nodes do not experience collisions and weaker nodes back off.

[0020] Virtual carrier sense is a logical abstraction that limits the need for physical carrier sense at the air interface to save power. The MAC layer frame header contains a duration field that specifies the transmission time required for the frame during which the medium will be busy. Stations listening to the wireless medium read the duration field and set their NAV, which is an indicator of how long the station must defer access to the medium. The NAV can be thought of as a counter that decrements at a uniform rate to zero. When the counter is zero, the virtual CS indicates the medium is idle; when non-zero, it indicates busy.

[0021] In LTE unlicensed

[0022] There are two types of LTE access on unlicensed frequencies: LAA, which acts as a supplementary downlink to a 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. The PBCH is carried only on the licensed carrier. However, the Rel-12 discovery reference signal (DRS), including the PSS, is transmitted on the unlicensed carrier at 40 ms intervals. Detecting only the DRS does not provide further information, i.e., the cell_ID, and even the operator cannot be determined. The MulteFire transmission does include the PBCH / PDSCH in its downlink transmission, now called the 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

[0023] The core of 3GPP NR version 15 PHY is a beam-based architecture. It is highly desirable that New Radio (NR) Unlicensed (NR-U) should make full use of as many features from NR as possible, including the beam-based architecture. Different from sensing wide-beam based eLAA, 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 detections, thus improving power efficiency. NR-U can consider introducing signaling to indicate the channel occupancy rate to improve spatial reuse and coexistence. This means new methods and signal designs are required in NR-U.

[0024] Methods and apparatuses for providing functions using a channel access indicator in NR-U are disclosed herein, such as: indicating the node's channel occupancy to nodes outside its cell; and indicating the node channel occupancy to nodes within its cell to assist 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.

[0025] The behavior of a node when it receives a CAI is also disclosed, i.e., how the node uses a timer to wait for sensing the channel. The information carried by the CAI for various use cases is also described.

[0026] Several procedures for enabling PUSCH to be transmitted at multiple starting positions within a UL grant are also described, where the starting positions are sent to the gNB via the CAI. These methods include:

[0027] ● Method for signaling the starting position of PUSCH candidates.

[0028] ● Process of adjusting UL DMRS based on the selected starting position of PUSCH.

[0029] ● Power boosting of DMRS can be performed for the first PUSCH after the UE's COT.

[0030] ● Power boosting of PUSCH RE can be performed for the first PUSCH after the UE's COT.

[0031] ● The UE can use different DMRS sequences to signal the selected PUSCH starting symbol.

[0032] ● The UE can use DMRS with a higher resource density for the first PUSCH after the UE's COT.

[0033] ● Truncation process to adapt PUSCH to available resources.

[0034] ● Process of adjusting MCS based on the selected starting position of PUSCH and facilitating the detection of the selected MCS at the gNB.

[0035] ● Process for transmitting the carried UCI

[0036] PHY layer signaling techniques for enabling CAI transmission on DL and UL are also described. The PHY layer signaling techniques include:

[0037] ● Signals such as PDCCH, PSS / SSS on DL;

[0038] ● PRACH, PUCCH on UL; and

[0039] ● Transmission based on the preamble, including:

[0040] ● Partial indication of CAI information on the preamble, and the remaining part through signals such as PDCCH or PRACH;

[0041] ● Asynchronous with symbol timing; and

[0042] ● Some bits providing information about the cell ID or about the channel occupancy time or about both through repetition and OCC.

[0043] The present invention content is provided to introduce some concepts in a simplified form, which will be further described in the following detailed implementation. The present invention content is neither intended to identify the key features or essential features of the claimed subject matter, nor intended to limit the scope of the claimed subject matter. In addition, the claimed subject matter is not limited to the limitations that solve any or all of the disadvantages pointed out in any part of the present disclosure. Description of the Drawings

[0044] A more detailed understanding can be obtained from the following description given by way of example in conjunction with the accompanying drawings.

[0045] Figure 1 Illustrates the CAI transmission, including (A) the CAI read by a general node and (B) the time indicating channel occupancy.

[0046] Figure 2 Illustrates sibling nodes whose detection of high energy in the channel is affected by the LBT process, including (A) the TDM UE of the cell – the UE to be transmitted later blocked by the UE transmitted first and (B) the UEs multiplexed in the same time / frequency resource because another access channel is blocked.

[0047] Figure 3A Illustrates the CAI transmission for spectrum reuse between sibling nodes.

[0048] Figure 3B Illustrates changing the energy detection threshold when detecting CAI from a sibling node during LBT.

[0049] Figure 3C Illustrates terminating the LBT when detecting CAI from a sibling node and performing CCA with a higher threshold.

[0050] Figure 3D Illustrates the CAI transmission of multiple UEs on the UL.

[0051] Figure 3E Illustrates the transmission of CAI by the gNB to indicate that sibling nodes (UEs) should use a higher threshold.

[0052] Figure 4 Illustrates a method for performing CCA with a higher threshold when detecting CAI from a sibling node.

[0053] Figure 5A Illustrates a method for identifying in-cell transmissions for spectrum reuse, where when detecting a sibling node CAI, the threshold is switched to a higher value during LBT.

[0054] Figure 5BIllustrates a method for identifying in-cell transmissions for spectrum reuse, where when a sibling node CAI is detected, CCA is performed with a higher threshold.

[0055] Figure 6 Illustrates a method for performing a handshake using CAI-1 and CAI-R.

[0056] Figure 7 Illustrates (A) performing a handshake using CAI-1 and CAI-R, (B) synchronizing the transmission of the CAI with the OFDM symbol boundary, and (C) asynchronizing the transmission of the CAI with the OFDM symbol boundary.

[0057] Figure 8 Illustrates the use of T in the CAI OCC Indicates the channel occupancy and release times.

[0058] Figure 9 Illustrates a method for sensing the channel (timer decrement) when receiving the CAI.

[0059] Figure 10 Illustrates the CAI indicating the updated T OCC Periodic transmission.

[0060] Figure 11 Illustrates the CAI indicating the updated T REL Transmission.

[0061] Figure 12 Illustrates the transmission of the CAI in UL during the channel occupancy time of the gNB.

[0062] Figure 13 Illustrates the T indication on different beams OCC Indication.

[0063] Figure 14 Illustrates a method for obtaining the CAI transmitted via DCI.

[0064] Figure 15 Illustrates a method for transmitting the CAI-R.

[0065] Figure 16 Illustrates the CAI-R of the UE scheduled according to the T Resp Duration from the CAI-1.

[0066] Figure 17 Illustrates a method for receiving the CAI via sibling nodes and general nodes in the case of cell coloring using the S bit.

[0067] Figure 18 Illustrates the CAI transmission using preamble repetition with the OCC code, including (A) synchronization with the OFDM symbol boundary and (B) asynchronization with the symbol boundary.

[0068] Figure 19 Illustrates an example of preamble resources in frequency.

[0069] Figure 20 Illustrates CA resources in a cell using a composite carrier (which is a multiple of 20 MHz).

[0070] Figure 21A Illustrates an embodiment of an example communication system in which the methods and apparatuses described and claimed herein can be implemented.

[0071] Figure 21B Is a block diagram of an example apparatus or device configured for wireless communication according to an embodiment shown herein.

[0072] Figure 21C Is according to an embodiment Figure 21A System diagram of RAN 103 and core network 106.

[0073] Figure 21D Is according to an embodiment Figure 21A System diagram of RAN 104 and core network 107.

[0074] Figure 21E Is according to an embodiment Figure 21A System diagram of RAN 105 and core network 109.

[0075] Figure 21F Is in which one or more apparatuses of the communication network shown in Figure 21A , 21C , 21D and 21E can be implemented. Block diagram of an exemplary computing system.

[0076] Figure 21G Shows multiple DCIs, which provide multiple starting positions for PUSCH.

[0077] Figure 22 Shows that multiple DCIs providing multiple starting positions for PUSCH are transmitted in the same CORESET.

[0078] Figure 23 Shows configuring multiple starting positions relative to the slot boundary.

[0079] Figure 24 Shows configuring multiple starting positions relative to the starting position of the scheduled PUSCH.

[0080] Figure 25 Shows that PUSCH starts before 10 and the old DMRS configuration remains valid during the duration of PUSCH, where the UE selects the starting position.

[0081] Figure 26 It shows that the PUSCH starts before 10 and the old DMRS configuration is invalid during the duration of the PUSCH, where the UE selects the starting position.

[0082] Figure 27 It shows that the PUSCH starts after 10 and the DMRS is mapped according to PUSCH mapping type B instead of PUSCH mapping type A.

[0083] Figure 28 It shows that the PUSCH starts after 10 and the DMRS is mapped according to PUSCH mapping type B instead of PUSCH mapping type A.

[0084] Figure 29 It shows the process of the access channel for transmitting the PUSCH with multiple starting positions.

[0085] Figure 30 It shows the OFDM symbol carrying the UL DMRS with the duration of the PUSCH duration, 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.

[0086] Figure 31 It shows the OFDM symbol carrying the UL DMRS of the PUSCH, where the starting position selected by the UE is different from the old OFDM symbol carrying the UL DMRS of the originally scheduled PUSCH.

[0087] Figure 32 It shows the OFDM symbol carrying the UL DMRS of the PUSCH, where the starting position selected by the UE is different from the old OFDM symbol carrying the UL DMRS of the originally scheduled PUSCH and the last OS carries the DMRS.

[0088] Figure 33 It shows the OFDM symbol carrying the UL DMRS of the PUSCH, where the starting position selected by the UE follows PUSCH mapping type B and is different from the old OFDM symbol carrying the UL DMRS of the PUSCH following PUSCH mapping type A of the originally scheduled PUSCH.

[0089] Figure 34 It shows the OFDM symbol carrying the UL DMRS of the PUSCH, where the starting position selected by the UE follows PUSCH mapping type B, while the old OFDM symbol carries the UL DMRS of the PUSCH following PUSCH mapping type A of the originally scheduled PUSCH.

[0090] Figure 35Shows the power boost of DMRS REs for the first PUSCH transmission in the COT for the UE.

[0091] Figure 36 Shows the power boost of the remaining DMRS REs after discarding some DMRS REs due to channel unavailability.

[0092] Figure 37 Shows the starting positions of PUSCH transmissions indicated by DMRS sequences: (A) Sequence #1 indicates that the PUSCH starts at OS#0. (B) Sequence #2 indicates that the PUSCH starts at OS#1. (C) Sequence #3 indicates that the PUSCH starts at OS#2. (D) Sequence #4 indicates that the PUSCH starts at OS#4.

[0093] Figure 38 Shows higher DMRS resource density and different timing resources for DMRS in the first PUSCH transmission in the COT of the UE.

[0094] Figure 39 Shows the UL preamble indicating the start of PUSCH transmission.

[0095] Figure 40 Shows the preamble resources in the PUSCH: (A) relative to the PUSCH resources. (B) relative to the carrier band.

[0096] Figure 41 Shows puncturing OFDM symbols during channel unavailability and transmitting the remaining OFDM symbols after the channel becomes available.

[0097] Figure 42 Shows the CA-RS-Group for CA-RS1: If LBT is successful in the spatial direction indicated by CA-RS1, then the gNB can transmit signals in the direction indicated by any RS in the corresponding CA-RS-Group.

[0098] Figure 43 Shows the UL transmission corresponding to the spatial direction of the CA-RS-Group.

[0099] Figure 44 Shows that the UE monitors DCI in its monitoring occasion after detecting the preamble.

[0100] Figure 45 Shows the preamble indicating the aperiodic CORESET / search space monitoring occasion.

[0101] Figure 46 Shows that the preamble and CORESET resources share the same OS.

[0102] Figure 47It shows 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.

[0103] Figure 48 It shows a UE that indicates the start of its channel access after the first PUSCH transmission, and this first PUSCH transmission does not occupy the authorized resources due to channel availability.

[0104] Figure 49 It shows the DMRS mapped according to PUSCH mapping type B based on the duration of the PUSCH with the starting position selected by the UE, rather than the PUSCH mapping type B with the original authorization.

[0105] Figure 50A It shows the candidate starting positions for multiple consecutive PUSCHs depending on each PUSCH.

[0106] Figure 50B It shows the candidate starting positions for multiple consecutive PUSCHs depending on the first symbol of the first PUSCH.

[0107] Figure 50C It shows the candidate starting positions for multiple consecutive PUSCHs relative to the boundary of the time slot.

[0108] Figure 50D It shows the candidate starting positions for multiple consecutive PUSCHs relative to the boundary of the time slot with a specific pattern P.

[0109] Figure 51 It shows an example of moving the entire PUSCH to a new starting position.

[0110] Figure 52A It shows that the PUSCH and the scheduled DMRS are shifted by two OFDM symbols relative to the original starting position, which is the same as the new starting position.

[0111] Figure 52B It shows that one of the scheduled DMRS symbols is discarded because it falls outside the end of the scheduled PUSCH.

[0112] Figure 53A It shows an example of shifting the PUSCH without crossing the time slot boundary.

[0113] Figure 53B It shows an example of shifting multiple scheduled PUSCHs in the time slot without crossing the time slot boundary.

[0114] Figure 54A It shows an example of shifting the PUSCH while keeping the position of the scheduled DMRS fixed.

[0115] Figure 54B An example of shifting the PUSCH is shown such that one of the scheduled DMRS symbols is discarded because it falls before the new starting position.

[0116] Figure 54C An example of transmitting a DMRS symbol in the first symbol of the PUSCH with the new starting position is shown because all of the originally scheduled DMRSs are discarded because they fall before the new starting position. Detailed Description

[0117] The following is a list of acronyms that may appear in the following description. Unless otherwise stated, the acronyms used herein refer to the corresponding terms listed below:

[0118]

[0119]

[0120]

[0121]

[0122] The 3rd 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. The most recent radio access technology (RAT) standards include WCDMA (commonly known as 3G), LTE (commonly known as 4G), and LTE-Advanced standards. 3GPP has started working on the standardization of the next generation of cellular technology, which is known as New Radio (NR), also known as "5G". The development of the 3GPP NR standard is expected to include the definition of the next generation of radio access technology (new RAT), which is expected to include the provision of new flexible radio access below 6 GHz, as well as the provision of new ultra-mobile broadband radio access above 6 GHz. The 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 range of 3GPP NR use cases with different requirements. The ultra-mobile broadband is expected to include the cmWave and mmWave spectrums, which will provide opportunities for ultra-mobile broadband access for, e.g., indoor applications and hotspots. In particular, with design optimizations specific to cmWave and mmWave, the ultra-mobile broadband is expected to share a common design framework with the flexible radio access below 6 GHz.

[0123] 3GPP has identified the various use cases that NR is expected to support, leading to various user experience requirements for data rate, latency, and mobility. The 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, handover and interworking, power savings), and enhanced vehicle-to-everything (eV2X) communications. Specific services and applications within 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, automotive eCall, 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 herein.

[0124] Figure 21A FIG. illustrates an embodiment of an example communication system 100 in which the methods and apparatuses 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 (which may generally or collectively be referred to as WTRU 102), radio access networks (RANs) 103 / 104 / 105 / 103b / 104b / 105b, core networks 106 / 107 / 109, public switched telephone network (PSTN) 108, Internet 110, and other networks 112, but it should be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of WTRU 102a, 102b, 102c, 102d, 102e may be any type of apparatus or device configured to operate and / or communicate in a wireless environment. Although each of WTRU 102a, 102b, 102c, 102d, 102e is Figure 21A - 21E depicted as a handheld wireless communication device in, it should be understood that for the various use cases contemplated for 5G wireless communications, each WTRU may include or be implemented as any type of apparatus or device configured to transmit and / or receive wireless signals, by way of example only, such apparatus or devices include user equipment (UE), mobile station, fixed or mobile subscriber unit, pager, cellular phone, personal digital assistant (PDA), smart phone, laptop computer, tablet computer, netbook, notebook computer, personal computer, wireless sensor, consumer electronics, wearable devices (such as smart watches or smart clothing), medical or e-health devices, robots, industrial equipment, drones, vehicles (such as cars, trucks, trains, or airplanes, etc.).

[0125] The communication system 100 may also include base stations 114a and 114b. Base station 114a may be any type of device configured to wirelessly interface with at least one of WTRUs 102a, 102b, and 102c to facilitate access to one or more communication networks, such as core networks 106 / 107 / 109, the Internet 110, and / or other networks 112. Base station 114b may be any type of device configured to wired and / or wirelessly interface with at least one of 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 core networks 106 / 107 / 109, the Internet 110, and / or other networks 112. RRHs 118a, 118b may be any type of device configured to wirelessly interface with at least one of WTRUs 102c to facilitate access to one or more communication networks, such as core networks 106 / 107 / 109, the Internet 110, and / or other networks 112. TRPs 119a, 119b may be any type of device configured to wirelessly interface with at least one of WTRUs 102d to facilitate access to one or more communication networks, such as core networks 106 / 107 / 109, the Internet 110, and / or other networks 112. By way of example, base stations 114a, 114b may be base transceiver stations (BTSs), Node-Bs, eNode Bs, home Node Bs, home eNode Bs, site controllers, access points (APs), wireless routers, etc. Although base stations 114a, 114b are each depicted as a single element, it should be appreciated that base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0126] Base station 114a may be part of RAN 103 / 104 / 105, and RAN 103 / 104 / 105 may further include other base stations and / or network elements (not shown), such as base station controllers (BSCs), radio network controllers (RNCs), relay nodes, etc. Base station 114b may be part of RAN 103b / 104b / 105b, and RAN 103b / 104b / 105b may further include other base stations and / or network elements (not shown), such as base station controllers (BSCs), radio network controllers (RNCs), relay nodes, etc. Base station 114a may be configured to transmit and / or receive wireless signals within a specific geographical area, which may be referred to as a cell (not shown). Base station 114b may be configured to transmit and / or receive wired and / or wireless signals within a specific geographical area, which may be referred to as a cell (not shown). A cell may be further divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Thus, in an embodiment, base station 114a may include three transceivers, e.g., one transceiver for each sector of the cell. In an embodiment, base station 114a may employ multiple-input multiple-output (MIMO) technology and thus may use multiple transceivers for each sector of the cell.

[0127] Base station 114a may communicate with one or more of WTRUs 102a, 102b, 102c via air interfaces 115 / 116 / 117, and air interfaces 115 / 116 / 117 may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, cmWave, mmWave, etc.). Any suitable radio access technology (RAT) may be used to establish air interfaces 115 / 116 / 117.

[0128] Base station 114b may communicate with one or more of RRHs 118a, 118b and / or TRPs 119a, 119b via wired or air interfaces 115b / 116b / 117b, and air interfaces 115b / 116b / 117b 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.). Any suitable radio access technology (RAT) may be used to establish air interfaces 115b / 116b / 117b.

[0129] RRH 118a, 118b, and / or TRP 119a, 119b may communicate with one or more of WTRU102c, 102c via air interface 115c / 116c / 117c, and air interface 115c / 116c / 117c may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, cmWave, mmWave, etc.). Any suitable radio access technology (RAT) may be used to establish air interface 115c / 116c / 117c.

[0130] More specifically, as described above, communication system 100 may be a multi-access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, base station 114a in RAN 103 / 104 / 105 and WTRU 102a, 102b, 102c or RRH 118a, 118b and TRP 119a, 119b in RAN 103b / 104b / 105b and WTRU 102c, 102d may implement radio technologies, such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may use Wideband CDMA (WCDMA) to establish air interfaces 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).

[0131] In an embodiment, base station 114a in RAN 103 / 104 / 105 and WTRU 102a, 102b, 102c or RRH 118a, 118b and TRP 119a, 119b in RAN 103b / 104b / 105b and WTRU 102c, 102d may implement radio technologies, such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may use Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) to establish air interfaces 115 / 116 / 117 or 115c / 116c / 117c respectively. In the future, air interfaces 115 / 116 / 117 may implement 3GPP NR technology.

[0132] In an embodiment, the base station 114a in RAN 103 / 104 / 105 and the WTRU 102a, 102b, 102c, or the RRH 118a, 118b and the TRP 119a, 119b in RAN103b / 104b / 105b and the WTRU 102c, 102d can implement radio technologies such as IEEE 802.16 (e.g., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, 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.

[0133] Figure 21A The base station 114c in can be, for example, a wireless router, a home node B, a home eNode B, or an access point, and can utilize any suitable RAT to facilitate wireless connectivity in a local area (such as a business location, home, vehicle, campus, etc.). In an embodiment, the base station 114c and the WTRU 102e can 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 can 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 can utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, etc.) to establish a pico cell or a femto cell. As Figure 21A shown, the base station 114b can have a direct connection to the Internet 110. Thus, it may not be required for the base station 114c to access the Internet 110 via the core network 106 / 107 / 109.

[0134] RAN 103 / 104 / 105 and / or RAN 103b / 104b / 105b can communicate with the core network 106 / 107 / 109, which can 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 WTRU 102a, 102b, 102c, 102d. For example, the core network 106 / 107 / 109 can provide call control, billing services, mobile location-based services, prepaid calls, Internet connectivity, video distribution, etc., and / or perform advanced security functions (such as user authentication).

[0135] Although not shown inFigure 21A is shown, but it should be appreciated that RANs 103 / 104 / 105 and / or RANs 103b / 104b / 105b and / or core networks 106 / 107 / 109 may communicate directly or indirectly with other RANs employing the same RAT as RANs 103 / 104 / 105 and / or RANs 103b / 104b / 105b or a different RAT. For example, in addition to being connected to RANs 103 / 104 / 105 and / or RANs 103b / 104b / 105b that may utilize E-UTRA radio technology, core networks 106 / 107 / 109 may also communicate with another RAN (not shown) employing GSM radio technology.

[0136] Core networks 106 / 107 / 109 may also serve as gateways for 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 providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices using common communication protocols such as the Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and Internet Protocol (IP) in the TCP / IP Internet protocol suite. Networks 112 may include wired or wireless communication networks owned and / or operated by other service providers. For example, network 112 may include another core network connected to one or more RANs, which one or more RANs may employ the same RAT as RANs 103 / 104 / 105 and / or RANs 103b / 104b / 105b or a different RAT.

[0137] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities. For example, WTRUs 102a, 102b, 102c, 102d, and 102e may include multiple transceivers for communicating with different wireless networks over different wireless links. For example, Figure 21A the WTRU 102e shown in may be configured to communicate with a base station 114a that may employ cellular-based radio technology and with a base station 114c that may employ IEEE 802 radio technology.

[0138] Figure 1 FIG. B is a block diagram of an example apparatus or device (such as, for example, a WTRU 102) configured for wireless communication according to an embodiment shown herein. As Figure 21BAs shown, the exemplary 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 peripheral devices 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, transceiver stations (BTSs), Node Bs, site controllers, access points (APs), home Node-Bs, evolved home Node-Bs (eNodeBs), home evolved Node-Bs (HeNBs), home evolved Node-B gateways, and proxy nodes, etc.), may include Figure 21B some or all of the elements depicted and described herein.

[0139] The processor 118 may be a general-purpose processor, a dedicated processor, a conventional processor, a digital signal processor (DSP), multiple 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 encoding, data processing, power control, input / output processing, and / or any other function that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, and the transceiver 120 may be coupled to the transmit / receive element 122. Although Figure 21B the processor 118 and the transceiver 120 are depicted as separate components, it should be appreciated that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0140] The transmit / receive element 122 may be configured to transmit signals to, 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 transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 may be a transmitter / detector configured to transmit and / or receive, for example, IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and receive RF and optical signals. It should be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0141] In addition, although the transmit / receive element 122 is shown in Figure 21Bis depicted as a single element, but the WTRU 102 can include any number of transmit / receive elements 122. More specifically, the WTRU 102 can employ MIMO technology. Thus, in an embodiment, the WTRU 102 can 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.

[0142] The transceiver 120 can be configured to modulate the signals to be transmitted by the transmit / receive elements 122 and demodulate the signals received by the transmit / receive elements 122. As described above, the WTRU 102 can have multi-mode capabilities. Thus, for example, the transceiver 120 can include multiple transceivers to enable the WTRU 102 to communicate via multiple RATs (such as UTRA and IEEE 802.11).

[0143] The processor 118 of the WTRU 102 can be coupled to the speaker / microphone 124, keypad 126, and / or the display / touchpad / indicator 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit), and can receive user input data therefrom. The processor 118 can also output user data to the speaker / microphone 124, keypad 126, and / or the display / touchpad / indicator 128. In addition, the processor 118 can access information from and store data in any type of suitable memory (such as non-removable memory 130 and / or removable memory 132). The non-removable memory 130 can include random access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 can include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In an embodiment, the processor 118 can access information from a memory that is not physically located on the WTRU 102 (such as on a server or a home computer (not shown)) and store data therein.

[0144] The processor 118 can receive power from the power supply 134 and can be configured to distribute power to and / or control other components in the WTRU 102. The power supply 134 can be any suitable device for powering the WTRU 102. For example, the power supply 134 can include one or more dry cells, solar cells, fuel cells, etc.

[0145] The processor 118 may also be coupled to a 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 instead of information from the GPS chipset 136, the WTRU 102 may receive location information via the air interface 115 / 116 / 117 from a base station (e.g., base stations 114a, 114b) and / or determine its location based on the timing of signals received from two or more nearby base stations. It should be appreciated that the WTRU 102 may obtain location information by any suitable location determination method while remaining consistent with the embodiments.

[0146] The processor 118 may also be coupled to other peripheral devices 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 peripheral devices 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, frequency modulation (FM) radio units, digital music players, media players, video game player modules, Internet browsers, etc.

[0147] The WTRU 102 may be implemented in other devices or apparatuses such as sensors, consumer electronics, wearable devices (such as smart watches or smart clothing), medical or e-health devices, 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 apparatuses via one or more interconnect interfaces (such as an interconnect interface that may include one of the peripheral devices 138).

[0148] Figure 21C is a system diagram of the RAN 103 and the core network 106 according to an embodiment. As described above, the RAN 103 may communicate with the WTRU 102a, 102b, and 102c via the air interface 115 using UTRA radio technology. The RAN 103 may also communicate with the core network 106. As Figure 21CAs shown, the RAN 103 may include Node Bs 140a, 140b, 140c, each of which may include one or more transceivers for communicating with WTRUs 102a, 102b, and 102c via air interface 115. Node Bs 140a, 140b, 140c may each be associated with a specific cell (not shown) within the RAN 103. The RAN 103 may also include RNCs 142a, 142b. It should be appreciated that the RAN 103 may include any number of Node Bs and RNCs while remaining consistent with the embodiments.

[0149] As Figure 21C shown, Node Bs 140a, 140b may communicate with RNC 142a. Additionally, Node B 140c may communicate with RNC 142b. Node Bs 140a, 140b, 140c may communicate with the respective RNCs 142a, 142b via the Iub interface. RNCs 142a, 142b may communicate with each other via the Iur interface. Each of RNCs 142a, 142b may be configured to control the respective Node Bs 140a, 140b, 140c connected thereto. Additionally, each of RNCs 142a, 142b may 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.

[0150] Figure 21C The core network 106 as shown 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 the core network operator.

[0151] The RNC 142a in the RAN 103 may be connected to the MSC 146 in the core network 106 via the 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 a circuit switched network such as the PSTN 108 to facilitate communication between the WTRUs 102a, 102b, and 102c and traditional landline communication devices.

[0152] The RNC 142a in the RAN 103 can also be connected to the SGSN 148 in the core network 106 via the IuPS interface. The SGSN 148 can be connected to the GGSN 150. The SGSN 148 and the GGSN 150 can provide the WTRUs 102a, 102b, 102c with access to a packet switched network, such as the Internet 110, to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0153] As described above, the core network 106 can also be connected to the network 112, which can include other wired or wireless networks owned and / or operated by other service providers.

[0154] Figure 21D is a system diagram of the RAN 104 and the core network 107 according to an embodiment. As described above, the RAN 104 can communicate with the WTRUs 102a, 102b, and 102c via the air interface 116 using E-UTRA radio technology. The RAN 104 can also communicate with the core network 107.

[0155] The RAN 104 can include eNode-Bs 160a, 160b, 160c, but it should be appreciated that the RAN 104 can include any number of eNode-Bs while remaining consistent with the embodiment. Each of the eNode-Bs 160a, 160b, 160c can include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c via the air interface 116. In an embodiment, the eNode-Bs 160a, 160b, 160c can implement MIMO technology. Thus, the eNode-B 160a, for example, can use multiple antennas to transmit wireless signals to the WTRU 102a and receive wireless signals from the WTRU 102a.

[0156] Each of the eNode-Bs 160a, 160b, and 160c can be associated with a particular cell (not shown) and can be configured to handle radio resource management decisions, handover decisions, scheduling of users in the uplink and / or downlink, etc. As Figure 21D shown, the eNode-Bs 160a, 160b, 160c can communicate with each other via the X2 interface.

[0157] Figure 21DThe core network 107 shown in FIG. may include a Mobility Management Entity (MME) 162, a Serving Gateway 164, and a Packet Data Network (PDN) Gateway 166. Although 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 the core network operator.

[0158] The MME 162 may be connected to each of the eNode-Bs 160a, 160b, and 160c in the RAN 104 via the S1 interface and may act 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 the initial attachment of the WTRUs 102a, 102b, 102c, etc. The MME 162 may also provide control plane functions for handover between the RAN 104 and other RANs (not shown) employing other radio technologies such as GSM or WCDMA.

[0159] The Serving Gateway 164 may be connected to each of the eNode-Bs 160a, 160b, and 160c in the RAN 104 via the 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 handover between eNode Bs, triggering paging when downlink data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, etc.

[0160] The Serving Gateway 164 may also be connected to the PDN Gateway 166, which may provide the WTRUs 102a, 102b, 102c with access to a packet switched network such as the Internet 110 to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0161] The core network 107 may facilitate communication with other networks. For example, the core network 107 may provide the WTRUs 102a, 102b, 102c with access to a circuit-switched network, such as the PSTN 108, to facilitate communication between the WTRUs 102a, 102b, and 102c and traditional landline communication devices. For example, the core network 107 may include 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 or may communicate therewith. Additionally, the core network 107 may provide the WTRUs 102a, 102b, 102c with access to the network 112, which may include other wired or wireless networks owned and / or operated by other service providers.

[0162] Figure 21E FIG. 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 communicates with the WTRUs 102a, 102b, and 102c via an air interface 117 using IEEE 802.16 radio technology. As discussed further below, communication links between different functional entities of the WTRUs 102a, 102b, 102c, the RAN 105, and the core network 109 may be defined as reference points.

[0163] As Figure 21E shown, 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 specific cell in the RAN 105 and may include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c via 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, etc. 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, etc.

[0164] The air interface 117 between the WTRUs 102a, 102b, 102c and the RAN 105 can be defined as the R1 reference point that implements the IEEE 802.16 standard. Additionally, each of the WTRUs 102a, 102b, and 102c can 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 can be defined as the R2 reference point, which can be used for authentication, authorization, IP host configuration management, and / or mobility management.

[0165] The communication link between each of the base stations 180a, 180b, and 180c can be defined as the 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 can be defined as the R6 reference point. The R6 reference point can include protocols for facilitating mobility management based on mobility events associated with each of the WTRUs 102a, 102b, 102c.

[0166] As Figure 21E shown, the RAN 105 can be connected to the core network 109. The communication link between the RAN 105 and the core network 109 can be defined as the R3 reference point, and the R3 reference point includes protocols for facilitating, for example, data transfer and mobility management capabilities. The core network 109 can include a Mobile IP Home Agent (MIP-HA) 184, an Authentication, Authorization, Accounting (AAA) server 186, and a gateway 188. Although each of the foregoing elements is depicted as part of the core network 109, it should be recognized that any of these elements can be owned and / or operated by an entity other than the core network operator.

[0167] The MIP-HA can be responsible for IP address management and can enable the WTRUs 102a, 102b, and 102c to roam between different ASNs and / or different core networks. The MIP-HA 184 can provide the WTRUs 102a, 102b, and 102c with access to a packet-switched network, such as the Internet 110, to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices. The AAA server 186 can be responsible for user authentication and support of user services. The gateway 188 can facilitate interworking with other networks. For example, the gateway 188 can provide the WTRUs 102a, 102b, 102c with access to a circuit-switched network, such as the PSTN 108, to facilitate communication between the WTRUs 102a, 102b, 102c and traditional landline communication devices. In addition, the gateway 188 can provide the WTRUs 102a, 102b, and 102c with access to the network 112, which can include other wired or wireless networks owned and / or operated by other service providers.

[0168] Although not shown in Figure 21E it should be appreciated that the RAN 105 can be connected to other ASNs and the core network 109 can be connected to other core networks. The communication link between the RAN 105 and other ASNs can be defined as the R4 reference point, and the R4 reference point can include a protocol for coordinating the mobility of the WTRUs 102a, 102b, 102c between the RAN 105 and other ASNs. The communication link between the core network 109 and other core networks can be defined as the R5 reference point, and the R5 reference point can include a protocol for facilitating interworking between the home core network and the visited core network.

[0169] Described herein and shown in Figure 21A 、 21C 、21D and 21E, the core network entities are identified by the names given to those entities in certain existing 3GPP specifications. However, it should be appreciated that in the future, those entities and functions may be identified by other names and certain entities or functions may be combined in future 3GPP specifications, including future 3GPP NR specifications. Therefore, Figure 21A 、 21B 、21C, 21D and 21E, the specific network entities and functions described and shown are provided only as examples, and it should be understood that the subject matter disclosed and claimed herein can be implemented or realized in any similar communication system, whether currently defined or future-defined communication systems.

[0170] Figure 21F is a block diagram of an exemplary computing system 90 in which Figure 21A 、21C One or more devices of the communication network shown in FIGS. 21D and 21E, such as certain nodes or functional entities in RAN 103 / 104 / 105, core network 106 / 107 / 109, PSTN 108, Internet 110, or other network 112. The computing system 90 may include a computer or a server and may be mainly controlled by computer-readable instructions, which may be in the form of software, wherever and however such software is stored or accessed. Such computer-readable instructions may be executed within the processor 91 to cause the computing system 90 to operate. The processor 91 may be a general-purpose processor, a dedicated processor, a conventional processor, a digital signal processor (DSP), multiple 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 the communication network. The coprocessor 81 is an optional processor different from the main processor 91, which may perform additional functions or assist the processor 91. The processor 91 and / or the coprocessor 81 may receive, generate, and process data related to the methods and devices disclosed herein.

[0171] In operation, the processor 91 fetches, decodes, and executes instructions and transfers information to and from other resources via the main data transfer path of the computing system, the system bus 80. Such a system bus connects the components in the computing system 90 and defines the medium for data exchange. The system bus 80 typically includes data lines for sending data, address lines for sending addresses, and control lines for sending interrupts and for the operating system bus. An example of such a system bus 80 is the PCI (Peripheral Component Interconnect) bus.

[0172] The memories coupled to the system bus 80 include a random access memory (RAM) 82 and a read-only memory (ROM) 93. Such memories include circuitry that allows for the storage and retrieval of information. The ROM 93 generally contains stored data that is not easily modified. The data stored in the RAM 82 can be read or changed by the processor 91 or other hardware devices. Access to the 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 virtual addresses into physical addresses when executing instructions. The memory controller 92 can also provide a memory protection function that isolates processes within the system and separates system processes from user processes. Thus, a program running in a first mode can only access the memories mapped by its own process virtual address space; it cannot access the memories within another process's virtual address space unless memory sharing between processes has been set up.

[0173] In addition, the computing system 90 can include a peripheral device controller 83 that is responsible for transferring instructions from the processor 91 to peripheral devices such as a printer 94, a keyboard 84, a mouse 95, and a disk drive 85.

[0174] A display 86 controlled by a display controller 96 is used to display visual output generated by the computing system 90. Such visual output can include text, graphics, animated graphics, and video. The visual output can be provided in the form of a graphical user interface (GUI). The display 86 can be implemented using a CRT-based video display, an LCD-based flat panel display, a gas plasma-based flat panel display, or a touchpad. The display controller 96 includes the electronic components required to generate the video signal sent to the display 86.

[0175] Additionally, the computing system 90 can include communication circuitry such as a network adapter 97 that can be used to connect the computing system 90 to an external communication network (such as Figure 21A 、 21B 、RAN 103 / 104 / 105, core networks 106 / 107 / 109, PSTN 108, Internet 110, or other networks 112 of 21C, 21D, and 21E) so that the computing system 90 can communicate with other nodes or functional entities of those networks. Alone or in combination with the processor 91, the communication circuitry can be used to perform the transmission and reception steps of certain apparatuses, nodes, or functional entities described herein.

[0176] Introduction of Channel Access Indicator (CAI) in NR-U

[0177] According to one aspect of the systems and methods disclosed herein, NR-U can use a Channel Access Indicator (CAI) to support channel access indication, which can be signaled to indicate information about channel occupancy, such as the cell occupying it, the occupied bandwidth / spatial direction, the occupied time, etc.

[0178] 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.

[0179] ● Sibling node – A node served by the same serving NR-U cell as the reference node. More specifically, the sibling nodes of a given node can be defined as any co-channel node or any co-channel user having the same serving cell as the given node. Note: Co-channel transmission can be a UL transmission made by a given UE or a DL transmission to a given UE. Node S is used to represent a general sibling node. In other words, a node located in the same NR-U serving cell as the reference node is considered a sibling node. This includes the gNB of the serving cell.

[0180] ● General node – A node 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 a cell from a different PLMN, or a node from another technology (such as WiFi). More specifically, a general node with respect to a given node can be defined as any co-channel node or any co-channel user having a different serving cell, or as any co-channel UE having a different serving cellular RAT or a non-cellular RAT different from the given node. Note: Co-channel transmission can be a UL transmission made by a given UE or a DL transmission to a given UE. Node g is used to represent a general general node.

[0181] The CAI can serve one or more of the following purposes:

[0182] ● Use case 1: Indicate occupancy for coexisting networks.

[0183] ● Use case 2: Allow nodes to identify in-cell transmissions and improve spectrum reuse.

[0184] ● Use case 3: Trigger a handshake from the receiver to ensure no obstruction due to hidden nodes when accessing the channel.

[0185] ● Use case 4: Achieve power savings by allowing the receiver to identify when its transmitter is transmitting.

[0186] Use case 1: Use the CAI to indicate occupancy for coexisting networks

[0187] When sibling nodes and general nodes detect a CAI, they can obtain the time of channel occupancy from the CAI; thus they do not need to perform channel sensing during that occupied time. Figure 1 (A) shows an example where the gNB transmits a CAI in a Cell 1 indicating the source of the transmission, i.e., the Cell 1 is occupying the transmission. It can also indicate its occupancy time of the channel. Nodes UE 1 from the Cell 1 will recognize it as an in-cell transmission. General nodes (such as UE 2 from an NR-U Cell 2 , UE 2 on an NR-UCell 2 gNB) will recognize it as a transmission from a node outside its cell but can read the occupancy time. Nodes in a WiFi network 3 can have the ability to detect and read a CAI from an NR-U network. Until the occupancy time of the Cell 1 has passed, the general node cannot perform LBT. Figure 1 (B) shows this method for a general node to respond after hearing a CAI from a Cell 1 , where, after the channel occupancy time of the Cell 1 , the node resumes CCA (Clear Channel Assessment). CCA is an initial channel sensing where energy detection (ED) is performed at least for a certain time with a certain threshold.

[0188] Generally, the CAI can be signaled in both DL and UL. In autonomous UL (AUL) and semi-permanent scheduling, resources for the UE can be configured semi-statically for the UE. It cannot be guaranteed that the UE's resources are within the MCOT of its gNB. In this case, the UE can perform a method similar to CAT 4 LBT to determine channel availability and transmit a CAI in UL after a successful LBT.

[0189] Use Case 2: Using CAI to Indicate Spectrum Reuse

[0190] When a node identifies that the channel is occupied by another node in its own cell, it can adjust the threshold of its energy detection accordingly – if the energy is from a sibling node, then it can use a higher energy detection threshold compared to the lower threshold usually used in CCA without a CAI to determine an LBT failure. Figure 4 The method in

[0191] This feature is particularly useful in the UL where multiple UEs are multiplexed in frequency or time and allows for better spatial reuse. When a UE detects in-channel usage and high energy within a cell, the CAI will enable it to transmit because the detected energy is from multiplexed in-cell UEs. Sibling nodes share the same channel resources through multiplexing. They can be multiplexed onto the same time / frequency resources, or only multiplexed in time, or only multiplexed in frequency, or multiplexed in both time and frequency. For example, in NR UL, multiple UEs (orthogonally) share PUCCH resources, multiple UEs non-orthogonally share resources in NOMA, or multiple UEs are time / frequency multiplexed for PUSCH. Taking two sibling nodes multiplexed in time as an example, as Figure 2 (A) can be seen, UE 1 has a UL transmission in mini-slot #1, while UE 2 has a UL transmission in mini-slot #2. Due to the energy level from UE 1 , UE 2 is blocked. Similarly, if two sibling nodes are multiplexed in the same frequency and time resources for PUCCH and perform CAT4 LBT for transmission, then UE 1 can access the channel earlier. The random backoff of UE 2 may be larger, so it listens to UE 1 and assumes that it cannot access the channel, as Figure 2 (B) can be seen. If the sibling node UE 2 performs energy detection, then it detects the energy from UE 1 and cannot transmit in the scheduled resources. Therefore, within an NR-U cell, although multiplexed nodes should be able to transmit in the scheduled resources, their CCA / LBT fails due to the higher energy levels from other sibling nodes.

[0192] As Figure 3A can be seen, UE 1 transmits the CAI. UE 2 identifies the sibling node transmission after hearing the CAI and transmits its scheduled multiplexed PUSCH.

[0193] To ensure that other UEs, especially multiplexed sibling node UEs, hear the CAI of the UE, this paper proposes using a method similar to CAT 4 LBT - which causes the UE to randomly back off. The UE that first obtains access to the channel transmits the CAI, while other UEs with a larger backoff hear this CAI. As Figure 3B and Figure 3C shown, UE 1 in UE2 previously obtained channel access and transmitted its CAI. The UE 2 starts to sense the channel with CCA as part of CAT 4 LBT. As it continues to sense the channel during its random backoff, it detects higher energy. Thus, the UE 2 listens for the CAI. It detects the CAI and identifies it as an in-cell transmission. At this point, the UE 2 can perform one of the following operations:

[0194] ● The UE 2 changes its LBT threshold to and continues to extend the sensing with that higher threshold. If the energy is within this threshold, then it will transmit its scheduled PUSCH in the FDM resource together with the UE 1 . This is shown in Figure 3A (B). The method is provided in Figure 5A .

[0195] ● The UE 2 ends its current LBT and resets its random backoff timer with the change. It performs CCA using , which is typically a short process (such as 25 μs CCA). If it is successful, then the UE 2 continues its scheduled PUSCH transmission. This is shown in Figure 3C . The method is provided in Figure 5B .

[0196] If the UE does not receive the CAI from the sibling node, then it can transmit its own CAI. Figure 3D shows an example where the UE 2 does not hear the CAI from the UE 1 and transmits its own CAI. Other sibling node UEs or gNBs can hear both the CAI of the UE 1 and the UE 2 . Thus, the CAIs from multiple UEs may conflict in time / frequency. According to one aspect, the UL CAI design can be robust to conflicts by using the orthogonality / low correlation between the CAIs from different UEs. One way to obtain orthogonality is to provide different frequency resources for the CAIs of different UEs. Another way to provide robustness is through sequences with good cross-correlation properties, such as PRACH.

[0197] The CAI can also be signaled by the gNB on the Cell 1 to indicate the occupancy time. The CAI can be to the Cell 1Implicitly indicate that a UE scheduled or configured to transmit within that occupancy time can do so with a higher CCA threshold. For example, in Figure 3E , upon receiving a CAI from its gNB, the UE 1 and the UE 2 perform a single instance of CCA and use a higher threshold to determine channel access.

[0198] For a UE, the threshold for LBT energy level sensing can be configured by the gNB as part of a UL grant, or configured via RRC in a cell-wide or UE-specific manner. For example, if two UEs are multiplexed on a frequency, where UE 1 occupies 80% of the frequency resources, while UE 2 occupies the remaining 20%, then the 2 used by UE can be higher than that of UE 1 . The gNB can configure a table of values for the V thresh value for the UE. It can indicate the actual value to be used as an index into the table. The index can 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 the field for indicating the index, then the UE can apply to LBT regardless of whether it has detected a CAI from a sibling node.

[0199] It can also provide values for RRC configuration to be used in certain scenarios - for example, since the gNB does not know the number of UEs that can access it, the V thresh can be configured as a specific value for PRACH signaling.

[0200] Alternatively, the UE can implicitly derive its threshold from a reference threshold configured for the BWP. If the UE occupies a portion of the bandwidth part, then it can scale the reference threshold by that portion.

[0201] The CAI can be used as a reservation signal to ensure efficient use of the spectrum.

[0202] Figure 4 Shows the general procedure at a node after receiving a CAI from a sibling node.

[0203] Use Case 3: Use CAI to handshake between Tx and Rx to overcome hidden nodes. The CAI indication channel from the transmitter 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-1 and CAI-R can be sent by both the gNB and the UE.

[0204] When the gNB sends CAI-I, it can wait for CAI-R before scheduling an authorization for the UE. CAI-1 can be transmitted after Cat 4 LBT because the initiating node intends to use the channel to transmit a payload to the responding node. The sensing at the responding node can take the form of CCA (it can be short interval sensing, such as 25 μs sensing in LTE, non-permitted for DRS in FR1), which is short and reduces the possibility of other nodes occupying the channel during sensing.

[0205] Figure 6 A method for establishing a handshake between two nodes is shown.

[0206] Figure 7 (A) illustrates the concept of a handshake between two sibling nodes, where the gNB initiates CAI-1 and the UE responds with CAI-R. The UE can also transmit CAI-1 on the UL, especially when performing the CAT 4 LBT procedure. If the channel of the gNB is clear, then the gNB can respond with CAI-R, after which the UE transmits UL signals such as PUSCH or PUCCH.

[0207] As Figure 7 (B) shows, CAI-R can be synchronized with the symbol boundary. To achieve this, the responding node transmits a reservation signal after LBT. Assuming that the originating node has symbol boundary alignment, then it receives CAI-R. Synchronous transmission is useful when the amount of information carried in the CAI is high and requires to be carried in signals such as PDCCH or PUCCH.

[0208] Alternatively, as Figure 7As shown in (C), CAI-1 and CAI-R can be transmitted asynchronously with respect to the symbol boundary. The CAI can carry only a few bits of information and can be signaled by being detectable through temporal correlation (such as with a preamble), in which case the asynchronous transmission of the CAI preferably keeps the latency low. Especially for CAI-R, this can keep the latency for completing the handshake at a minimum. The responding node can transmit a reservation signal after the CAI-R to reserve the channel for at least the duration it takes for the initiating node to detect the channel so that no other node can occupy the channel. Then, the initiating node can transmit to the responding node without performing LBT again. Thus, the reservation signal can be transmitted after the CAI-R is transmitted.

[0209] The reservation signal can be generated by repeating the CAI-R signal for a desired duration.

[0210] Since the gNB can use the CAI-R to evaluate the UE's environment when other multiplexed UEs are transmitting, the gNB may occasionally trigger the CAI-R of a given UE and use the result to determine future scheduling. The UE can also transmit the detected energy level (during LBT) back to the gNB. This helps to detect the impact of interference from sibling UEs on a given UE in the UL; the gNB can make decisions regarding multiplexed UEs (orthogonal or non-orthogonal) based on the CAI-R. In this case, the UE can be RRC-configured with resources for the CAI-R but transmits the CAI-R only when triggered by the CAI-I.

[0211] Use Case 4: Using CAI to Enable Power Saving

[0212] 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, in which 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.

[0213] Methods Related to CAI

[0214] Propagation Timing of CAI

[0215] If Node 1 transmits the CAI at time tms, then T REL ms can be defined as the time when Node 1 releases the channel. Thus, T REL = t + T OCC where T OCC ms is the indication time of channel occupancy. T REFIt can be defined as the duration of a known interval (such as a time slot or an OFDM symbol or a subframe or a half-frame) in the reference numerology. For the remaining discussion, consider an example where the time slot duration of the reference numerology gives T REF T OCC (in ms) can be defined as a multiple of T REF . Thus, CAI can use D bits to indicate T OCC with respect to the reference time slot duration.

[0216] Node 1 can obtain the maximum T OCC , whose value T OCC = T MCOT , where T MCOT is the time of the MCOT of Node 1 for that channel access instance, and T MCOT can be based on the priority class of the LBT used in the channel access. In this case, it may not be possible to transmit the M bits for the MCOT separately.

[0217] Figure 8 gives an example for indicating T OCC in the CAI. Here, Node 1 accesses the channel with T MCOT = 10 ms and transmits the CAI in time slot N of the frame. Node 1 intends to use the channel for 7 time slots and then release it. Thus, the CAI indicates T OCC = 7 ms, assuming T REF = 1 ms.

[0218] Node S and Node g can operate on T OCC using the following method. At Node S and Node g , after receiving the CAI, set the channel availability timer to T OCC . Assume that Node S and Node g know T REF . Each T REF counter decrements. Node S and Node g expect the channel to be available when the timer reaches 0.

[0219] CAI can be transmitted at the start of a time slot to ensure that the channel is truly released when the counter is reset. However, it is not always possible to transmit the CAI at the start of a time slot. Additionally, to address the propagation delay and receiver latency to decode the CAI, after the timer reaches c ≥ 0, Node S and Node g can start monitoring the channel. A typical setting can use C = 1.

[0220] Figure 9 Shows a method of using a timer at a general node.

[0221] Furthermore, for a higher probability of detectability and to ensure that UEs with different DRX configurations can still receive the CAI, the CAI can be transmitted periodically or multiple times in a known pattern within the COT. There can be cases where the UE is not configured to receive the CAI; thus, multiple instances increase the chance of receiving the CAI. Figure 10 An example is shown in REL where the CAI is sent in time slots #0 and #5 of a frame. Both CAIs indicate the same T OCC , but in time slot #5 T

[0222] It is also proposed herein that Node 1 can increase or decrease its expected occupancy time within its MCOT and indicate this update in the subsequent CAI. Figure 11 Shows an example where in the first CAI transmitted when the channel is available T OCC = 7 ms. The next CAI transmission changes by incrementing it by 2 ms to the updated T OCC = 4 ms. At Node S and Node g , when the first CAI is received, the channel availability timer is set to T OCC , and it decrements every time slot (T REF ms). In this example T REF equals the time slot duration of 1 ms. When the second CAI is received, the timer is updated to the new value of T OCC = 4 ms, and then the counter decrements until it reaches one or zero, and then Node and Node g attempt channel access.

[0223] Generally, if a new CAI is received from any cell, then this method can be applied – when a node detects a new CAI, it updates the channel availability timer value to the latest value of T OCC , and starts decrementing every T REFms decreasing timer.

[0224] UL transmission within the MCOT of the gNB

[0225] When a transmitter such as a gNB occupies a channel, it indicates its T in the CAI OCC , thus providing value. However, within the T OCC duration, it may allow the UE to transmit on the UL. Additionally, the UE may transmit a UL CAI to indicate in-network operation to other UEs that may also attempt to access the channel, or if the gNB requests a response, then it may transmit a CAI-R. In this case, in the UL CAI proposed herein, its T OCC is indicated as the time to instead of the duration of its channel occupancy.

[0226] Figure 12 Shows an example where the UL transmission from the UE 1 is only one time slot, but its UL CAI indicates T OCC = 2 ms, such that the channel availability timers at Node S and Node g decrease based on and are not affected by the UL CAI.

[0227] It is proposed herein that the UE may have knowledge of T REL from the DL CAI or CAI-1, or it may receive the explicit value of through authorization.

[0228] CAI with omnidirectional and spatial LBT

[0229] If omnidirectional LBT is performed, the channel can be accessed simultaneously on multiple beams. It is proposed herein that the node may have different T OCC for each beam, while the MCOT is the same for all beams. The CAI can be sent on multiple beams to indicate the occupancy of the channel, including T OCC for each beam. However, if all beams have the same T OCC , then only one field may be required to indicate T OCC for all beams.

[0230] If spatial LBT is performed, the gNB may have different T REL for different beams. Also in this case, the CAI may carry T OCC for each beam.The information. Therefore, a receiver receiving one of the CAIs does not need to detect the CAI on other beams to know the network occupancy in multiple spatial directions. This can save some computational overhead. The spatial direction can be indicated as spatial QCL with respect to one of the signals in DRS or SSB, such as a certain CSI-RS in PBCH DMRS or DRS. Figure 13 shows an example where the gNB has obtained channel access on beams B1 and B2. However, for the beams, T OCC is different. The CAIs transmitted on B1 and B2 indicate values for the two beams. Also, the CAI on some beams can be CAI-1 and can carry a trigger for handshaking, while the CAI on other beams may not carry a trigger signal and may not indicate channel occupancy. Also, even if the gNB obtains channel access to these beams at the same time, the positions of the CAIs on different beams can be different because the gNB may have to sweep the beams to transmit the CAIs.

[0231] The information carried in the CAI

[0232] The following information can be carried in the CAI:

[0233] ● A field cellID that 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 through an operation such as can be fewer, where L can be a power of 2 such as 64 or 128 – this allows keeping the overhead small while allowing different cells to be distinguished. The cellID helps the listening node identify the cell occupying the channel.

[0234] ● A transmitter ID field transmitterID of T bits

[0235] ○ If the gNB (the TRP in the network) is transmitting, then the T bits can be set to a value in one of the following ways

[0236] ■ A fixed value shared by all NR-U networks

[0237] ■ A cell-specific value provided in the SI of the cell.

[0238] ■ T = 0; if the field can be absent, then it is implicitly indicated that it comes from the gNB.

[0239] ○ If the UE is transmitting, then the T bits are set to a value based on its ID The ID can be an ID such as C-RNTI or CS-RNTI, or a part of C-RNTI or CS-RNTI, which is configured by the network to which it is attached.

[0240] ● Receiver ID field receiverID in the R bit, where R can be equal to T.

[0241] ■ If the gNB (TRP in the network) is receiving, then the R bit can be set to a value By one of the following ways, a fixed value shared by all NR-U networks

[0242] ■ A cell-specific value provided in the SI of the cell.

[0243] ■ T = 0; if the field can be absent, then it implicitly indicates that it comes from the gNB.

[0244] ○ If the UE is receiving, then set the value based on the receiver ID (such as a part of C-RNTI or CS-RNTI or C-RNTI or CS-RNTI)

[0245] ● One-bit field responseIndicator can indicate whether the CAI requires a response from the receiver when set to 1, and when set to 0, the CAI does not require a CAI-R from the receiver.

[0246] ● CAI-I can carry a field resourceCAIR of the P bit to indicate the resource for transmitting the CAI-R.

[0247] ● CAI-I can carry a field triggeredUEID of the U bit to indicate the ID of the UE that must respond with a CAI-R.

[0248] ● CAI-R can carry a field detEnergy of the E bit to indicate the energy detected during LBT before the CAI-R. By assigning predefined thresholds for different energy levels, the number of bits E can be kept small. Knowing the energy detected by the responding node can help the initiating node evaluate the environment of the responder, especially when multiple nodes are multiplexed together. Thus, an initiating node such as the gNB can set the threshold level for LBT at the responding node.

[0249] The following fields can be defined for each numBeam for which the CAI can carry its information. For omnidirectional LBT, numBeams = 1; therefore, the following fields use a single instance. For spatial LBT, numBeam can be defined in the specification for different unlicensed bands in FR1 and FR2, or numBeam can be configured in the SI of the cell; numBeams can be set to the number of SSBs in the cell. The instances in the payload can be sorted in ascending order of the SSB index.

[0250] ● The intended channel occupancy time represented by the D-bit field intendedChannelOccTime is T OCC ms of expected time. This can be indicated in the form of the number of time slots of the reference numerology, such as 15 KHz for FR1 and 120 KHz for FR2.

[0251] ● The field mcotTransmitter, which indicates the duration T MCOT ms of MCOT. It is given by M bits such that T OCC ≤T MCOT .

[0252] ● The field freqResourceMCOT indicates the frequency resource on which the channel will be accessed. This allows the listening node to access channels outside the indicated frequency band.

[0253] Generally, since CAI is signaled for different purposes (such as indicating occupancy time or use in the network or handshake), depending on the use case, it can carry different fields and different amounts of information.

[0254] The CAI on one cell can indicate channel occupancy on other aggregated NR-U cells. For example, an NR-U PCell / PSCell can indicate its own CAI along with other aggregated NR-U SCells.

[0255] Candidate PUSCH start positions

[0256] Performing LBT before the UL PUSCH imposes uncertainty on when the UE will be able to access the channel. Therefore, allowing the UE to have multiple start positions in one or more time slots is beneficial for coping with channel uncertainty.

[0257] The following two aspects must be considered to support the (one or more) variable start positions of the PUSCH.

[0258] a. Signaling candidate start positions for the PUSCH: The burden on the gNB for detecting the start position must be minimized. The gNB can limit the number of start positions of the first PUSCH transmission from the UE within the UE's COT to simplify the hardware requirements for detecting the PUSCH.

[0259] b. UL Channel Access Indication of UE: Indication of the starting position of the UE. Depending on the set of allowed starting positions, the UE can indicate the selected starting position of the first PUSCH transmission within its COT. Thus, the CAI can be transmitted by the UE on UL to indicate the expected time of channel occupancy. The UL CAI can be explicitly indicated by a new signal such as an RS or a preamble sequence, or can be implicitly indicated by an existing signal such as the DMRS of the PUSCH. By detecting the UL CAI, the gNB identifies the starting position of the UE's PUSCH. For example, if the presence of the DMRS can unambiguously indicate the starting position, then the gNB can detect the starting position of the UE PUSCH by detecting and processing the UE's DMRS (auto - correlation or cross - correlation). Otherwise, the gNB can detect it by performing energy detection on the received PUSCH symbol - by - symbol.

[0260] Signaling the candidate starting positions of the PUSCH

[0261] The gNB can potentially detect the presence of PUSCH transmission by detecting the DMRS signal from the UE. However, the gNB has to determine the start of the PUSCH transmission, which can vary depending on the UE's channel access. The gNB can blindly decode the PUSCH for all candidate PUSCH starting OSs. For example, consider a UL grant for a 14 - OS slot. But the UE can only obtain channel access from OS#2 and punctures the PUSCH for OS#0 and OS#1. Then, the gNB receives the transmission and assumes the PUSCH starts at OS#0 for decoding. If it fails, it can decode the PUSCH for the PUSCH starting position OS#1. If it fails again, it can decode the PUSCH for the PUSCH starting position OS#2, and so on until the PUSCH is successfully decoded. If it cannot be decoded, then assuming it starts at OS#0 of the slot, the PUSCH is buffered and a re - transmission of the PUSCH is scheduled. Assuming the re - transmission is received in full, assuming the original transmission starts at OS#0, then the gNB can decode it by chase combining. If it fails, then assuming the original transmission starts at OS#1, the gNB can decode it by chase combining. If it fails again, then assuming the original transmission starts at OS#2, the gNB can decode it by chase combining - if successful at this attempt, then stop the transmission. This blind decoding process incurs a high hardware complexity for the gNB.

[0262] Moreover, it can be seen that it is beneficial to enable the gNB to know the starting position of the PUSCH to minimize blind decoding. If information is made available during the transmission of the PUSCH itself 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 chase combining. However, even if the CAI is not available to the gNB when processing the PUSCH, if the CAI information can be transmitted to the gNB before the scheduled retransmission, it will also enable the gNB to reduce blind decoding when handling retransmissions. According to one aspect, the UE can transmit its channel access information through a preamble or UCI; this can indicate the time when its COT starts, and in addition, it can also indicate when the UE's COT ends. The gNB identifies the starting position of the PUSCH therefrom and identifies the punctured symbols in the original transmission before it performs chase combining with the retransmission. This concept is shown in Figure 48 where the start of the COT is indicated by the UE through the UCI on the PUSCH; this occurs after the end of the first PUSCH transmission starting on OS#2.

[0263] To make the overhead of blind decoding acceptable at the gNB, the UE can be restricted from starting the transmission of the PUSCH from certain starting positions. A method is disclosed herein where the gNB can 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 for different PUSCH starting positions (such as UL DMRS configuration, MCS, TPC, etc.). For this purpose, for example, the gNB can use the same values of the new data indicator (NDI) and redundancy version (RV) on multiple DCIs, but it can adjust fields such as time domain resource assignment, MCS, TPC. In this case, the UE can interpret the reception of multiple UL grants with the same NDI and RV values as alternatives, and the UE can use only one of the UL grants based on the result of LBT on the UE side while ignoring the other UL grants. To provide the UE with sufficient processing time to prepare the PUSCH based on the starting position, an earlier DCI can be associated with a UL grant with an earlier starting position. For example, Figure 21G shows three DCIs that provide different starting positions for the PUSCH, and the UE can deploy only one of them based on the result of LBT on the UE side.

[0264] Alternatively, all DCIs can be transmitted in the same CORESET, for example as shown in Figure 22As shown. Those DCIs can carry the same NDI and RV to indicate that the provided UL grants are alternatives to each other, and the UE can select only one grant and ignore the other provided grants. The UE can first use the UL grant that provides the largest amount of resources, followed by the UL grant that provides the second largest amount of resources, and so on.

[0265] A new field in the 1-bit size field of the DCI, for example, called the DCI repetition flag, which can indicate that all DCIs carrying the same RV and NDI with the repetition 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. Conversely, if the repetition flag is set to zero, then one DCI can overwrite the other DCIs. Here, the UE does not select which DCI to use. Instead, the gNB determines the DCI that can be used according to the following rules, for example:

[0266] ● The DCI transmitted in a later CORESET can overwrite the DCI transmitted in an earlier CORESET; and

[0267] ● If DCIs are transmitted in the same CORESET, then the DCI transmitted in the lowest PRB can overwrite the DCI transmitted in a higher PRB.

[0268] According to another aspect, a single DCI can provide multiple starting positions. For example, the following information can be transmitted together with this DCI and with a C-RNTI scrambled CRC (other RNTIs can be used as applicable):

[0269] ● The number of starting positions, which indicates the number of candidate PUSCH starting positions that the UE can use according to the LBT result. The size of this field can be defined by a higher layer parameter (for example, the RRC parameter called maxNumStartPosit).

[0270] ● Or / and for each candidate starting position, a dedicated time domain resource assignment can be used to signal the starting position of each candidate PUSCH starting position. The bit width of this field is determined to be 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.

[0271] ● 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.

[0272] ● Alternatively, and / or for all candidate PUSCH starting positions, the NDI and RV can be the same.

[0273] ● An antenna port field for each candidate PUSCH starting position.

[0274] To reduce the overhead of transmitting multiple DCIs to indicate different starting positions for the PUSCH, the UE can select one of multiple candidate positions given by a higher layer parameter, such as the RRC parameter named PUSCH-start-Positions-set. The set of candidate positions can be relative to a time slot or relative to the scheduled PUSCH. If PUSCH-start-Positions-set is relative to a time slot, then the UE can select a candidate starting position from those that overlap with the original PUSCH grant. Figure 23 An example of PUSCH-start-Positions-set is shown, which provides multiple PUSCH starting positions relative to a time slot at symbols {0, 2, 5, 8, 10}. In this example, the PUSCH is scheduled to start from OS 4. Depending on the LBT result at the UE side, the PUSCH starting position can be at the start of the UL grant, as indicated by the DCI, or at one of the candidate starting positions that overlap with the grant (which are symbols {5, 8, 10}).

[0275] Alternatively, the candidate starting positions can be given by a higher layer parameter (such as the RRC parameter PUSCH-start-Positions-set) relative to the original starting position of the PUSCH given in the UL grant. In other words, the index of the actual symbol of the candidate starting 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 starting positions exceed the end position of the scheduled PUSCH, then the UE can ignore those candidate positions. By way of illustration, Figure 24 An example is shown where PUSCH-start-Positions-set = {2, 5, 7}, and the original starting position provided by the UL grant is the 4th symbol. Thus, 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 result.

[0276] Moreover, to avoid signaling the candidate start positions, they can be defined according to some rules either relative to the slot boundary or relative to the PUSCH grant itself. For example, each even / odd symbol can be a candidate start position. In yet another example, the candidate start positions can follow a certain pattern, like every L-th symbol after the first symbol in the granted PUSCH or in the slot. For example, L = 1 means every other symbol is a candidate start 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, it can be given by Table 2.

[0277] Table 2 Candidate start positions according to the scheduled MCS

[0278]

[0279] In Table 2, I MCS is the MCS for a given DCI providing the PUSCH grant, and for i ∈ {1, …, N}, the MCS th_i 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, i.e., MCS th_(i-1) = MCS th_i , then the L of the associated row where both MCS thresholds appear is disabled.

[0280] Table 3 illustrates an example of the dependence of the number of start positions and 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 each symbol. But if the duration of the PUSCH grant is 4 symbols, then L can be set to 1, which means 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 a higher layer parameter.

[0281] Table 3 Candidate start positions according to the scheduled PUSCH duration

[0282]

[0283] Other mathematical rules can also be applied to define the index of the candidate starting position, such as the OFDM symbol whose index (l) satisfies l mod M = 0, where M can depend on some of the original PUSCH grant parameters, such as MCS, the authorized duration (in symbols), etc. To establish the functional dependence of M on any of the original PUSCH grant parameters, a table similar to Table 2 can be used, for example. If any of the foregoing rules are applied with respect to the slot boundary, the UE can consider only the candidate starting positions that overlap with the UL grant.

[0284] On the other hand, explicit (using higher layer parameters) and implicit (according to specified rules) indication of the candidate starting position can be combined. For example, the candidate starting position can be the union of the positions given explicitly and implicitly. Also, in the absence of an explicit indication of the candidate starting position, the UE can apply the implicit indication.

[0285] It should be understood that the solutions mentioned above and / or any possible combinations thereof can be extended to provide the UE with possible candidate starting positions for multiple scheduled consecutive or non - consecutive PUSCHs via either a single or multiple UL grants. As a possible solution, the RRC parameter can provide the UE with the position(s) of the candidate starting position(s). These positions can be relative to the scheduled PUSCH or relative to the slot boundary. Then, the UE can consider only the positions that overlap with the scheduled PUSCH.

[0286] Figure 50A An example of the candidate starting position is configured as a shift from the first OFDM symbol in each scheduled PUSCH, and the shift value can be indicated by higher layer signaling (such as RRC parameters). As Figure 50A shown, the shift value can depend on the PUSCH index. For example, in PUSCH k, the candidate starting position is separated by S k where k is the index of the PUSCH. The UE can be indicated by higher layer signaling with the shift values for consecutive PUSCHs. For example, a set of shift levels such as {a, b, c, d, …} can be indicated to the UE. Then, the UE can set S 0 = a for PUSCH 0, set S 1 = b for PUSCH 1, and so on. Alternatively, the UE can be indicated by higher layer signaling with a single parameter, and the UE can use this single parameter to derive the positions of the candidate starting positions for each PUSCH. For example, it can vary according to the PUSCH index number.

[0287] Alternatively, for example, as Figure 50BAs shown, starting from the first OFDM symbol in the first scheduled PUSCH, the candidate PUSCH starting positions can be separated by a shift S. Other rules can also be applied to define the positions of the candidate starting positions. Moreover, in addition to those indicated by higher layer signaling, the UE can also consider the first OFDM symbol of each PUSCH as a candidate starting position.

[0288] Figure 50C Illustrates the case of defining candidate starting positions relative to the slot boundary. The number and positions of the candidate starting positions can be the same across each slot, or can vary from one slot to the next. Higher layer signaling can indicate these positions. In addition to the first OFDM symbol in each PUSCH, the UE can also consider candidate starting positions that overlap with any scheduled PUSCH as valid candidate starting positions, and the UE can use such valid candidate starting positions 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 higher layer can indicate the index of the OFDM symbol in each slot that the UE can use as a candidate starting position. For example, a 14-bit sized bitmap can indicate which OFDM symbols can be used as candidate starting positions if the corresponding bit is set to one. Moreover, each slot in a subframe / radio frame can have a different position for the candidate starting position, the concatenated bitmap for each slot can be signaled to the UE, and the positions of the candidate starting positions are repeated in each subframe or radio frame. Also, the gNB can define a pattern over a certain number of slots, where one set of slots has a certain candidate starting position and other sets have different candidate positions. This pattern can be applied repeatedly. For example, Figure 50D Shows a pattern P = 101 over 3 slots, where the slots corresponding to 1 have four candidate starting positions and the slots corresponding to 0 have 2 candidate starting positions. This pattern repeats every three slots.

[0289] The gNB can semi-statically indicate a specific set of configurations of the candidate starting positions to enable the gNB to flexibly adjust these configurations. For example, the gNB can provide the UE with multiple higher layer configurations indicating different sets of arrangements of the candidate starting positions, and then the gNB can use MAC-CE to select an appropriate configuration, for example, by pointing to the higher layer message ID carrying these configurations.

[0290] In addition, the gNB can dynamically indicate an appropriate configuration of the candidate starting positions by using DCI. For example, the length is equal to a bit field, where K is the number of configurations indicated by higher layer signaling. This bit field can be indicated in the DCI carrying the (one or more) grants or in a separate DCI in the UE-specific search space or in the group common search space with an appropriate RNTI. Also, the gNB can signal to the UE a subset of candidate starting positions using a MAC-CE, and then the gNB can use the DCI to indicate the configuration of the selection of the candidate starting positions.

[0291] UL channel access indication by the UE

[0292] Adjust DMRS scheduling based on the PUSCH starting position

[0293] For PUSCH mapping type A, the position(s) of the DMRS symbol(s) is / are defined relative to the slot boundary, and if the UE fails to acquire the channel according to the scheduled / configured grant, it will result in ambiguous behavior. For example, if multiple starting positions are provided by multiple dedicated DCIs, as shown in FIGS. 21 and Figure 22 as shown, i.e., one-to-one mapping of the DCI 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, in terms of signaling and UE power consumption, this may require a large amount of overhead to decode multiple DCIs for the same grant. Therefore, to alleviate this burden, signaling the candidate starting positions explicitly (using higher layer parameters) or implicitly (according to specified rules) can be more useful than using multiple DCIs. However, such static configurations may not be sufficient to adjust the DMRS scheduling based on the starting position of the PUSCH selected by the UE. Next, several embodiments for addressing this challenge are described.

[0294] For single UE MIMO (SU-MIMO), several alternatives can be adopted.

[0295] The PUSCH starts before l 0 before

[0296] If the UE is at l 0Previously accessed the 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), then as long as the DMRS symbols of the PUSCH at the starting position selected by the UE and its new duration are the same as those of the PUSCH with the old duration, the UE can deploy the configured and scheduled UL DMRS. For example, if the PUSCH duration is equal to 10, 11, or 12 OFDM symbols, then the DMRS occupies symbol l 0 , 9, as shown in Table 4 (see 3GPP TS 36.211, Physical channels and modulation (Release 15), V15.3.0).

[0297] Table 4 DMRS positions for PUSCH mapping type A with dmrs-AdditionalPosition = 1 and single-symbol DMRS with intra-slot hopping disabled

[0298]

[0299] Figure 25 Shows an example for the PUSCH that is scheduled to be transmitted over 12 OFDM symbols from OS 0 to OS11 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 positions OS1 and OS2 shown in the figure, then the durations of the PUSCH with the starting positions selected by the UE are 11 and 10 respectively. Therefore, the UE can still use the same scheduled DMRS.

[0300] On the other hand, if the duration of the PUSCH with the starting position selected by the UE uses a DMRS configuration different from the original PUSCH duration, then the UE can follow the new DMRS configuration associated with the new PUSCH duration with the same number of additional DMRS symbols. Figure 26An example of a PUSCH is shown. The PUSCH was initially scheduled to have a duration of 10 symbols from OS 0 to OS 9 and one additional UL DMRS symbol, but the UE was unable to access the channel at OS 0. However, if the UE accesses the channel at OS1 or OS2, then the duration of the PUSCH with the starting position selected by the UE 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 PUSCH durations of 8 and 9 OFDM symbols. In this case, the DMRS should be located at OSl 0 , 7 as shown in the figure.

[0301] The PUSCH starts from l 0 or starts at l 0 and starts after

[0302] If the UE accesses the channel starting from symbol l 0 given by the higher layer parameter dmrs-TypeA-Position or starts after l 0 , then the UE may assume that the PUSCH mapping type A (where the DMRS is mapped relative to the slot boundary) effectively changes to the PUSCH mapping type B (where the DMRS is mapped relative to the PUSCH based on the new PUSCH duration). In other words, the UE may set l 0 to zero and map the DMRS according to the new PUSCH duration and the number of additional DMRS symbols given by the higher layer parameter dmrs-additionalPoistion. Figure 27 An example for the PUSCH is shown. The PUSCH is scheduled for transmission over 12 OFDM symbols from OS 0 to OS11, 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), then 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 may map the UL DMRS according to the new PUSCH duration of 7 OSs following mapping type B and 4 relative to the start of the PUSCH. 0

[0303] Table 5 PUSCH DMRS positions for PUSCH mapping types A and B

[0304]

[0305] As another example, Figure 28A PUSCH is shown, which 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 starts accessing the channel from OS 7, which makes the duration of the PUSCH with the starting position selected by the UE four OFDM symbols, with only one symbol carrying DMRS and no additional DMRS positions.

[0306] Although in the previous example, these aspects were illustrated for a single-symbol DMRS with one additional DMRS position, these aspects still apply to a single-symbol DMRS with any additional number of DMRS positions, and also to a double-symbol DMRS with any additional number of DMRS positions.

[0307] Figure 29 An example process is illustrated, where the DMRS configuration can be adjusted according to the candidate PUSCH starting position. In Figure 29 the example, first, the gNB transmits a request for the authorized 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, then the process ends. If the channel is not available, then the UE attempts to access the channel at a new starting position. To access the channel before Io, the UE selects the UL DMRS configuration according to the PUSCH mapping type A and the new PUSCH duration, but has the same configuration as the scheduled DMRS in terms of the OM RS type (1 or 2), the number of additional DMRS positions, and the single or double DMRS symbols. To not access the channel before Io, the UE selects the UL DMRS configuration according to the PUSCH mapping type B and the new PUSCH duration, but has the same configuration as the scheduled DMRS in terms of the DMRS type (1 or 2), the number of additional DMRS positions, and the single or double DMRS symbols. In either case, the UE transmits the PUSCH with the new DMRS configuration.

[0308] The case of multi-user MIMO (MU-MIMO), i.e., the case where the DMRS of other UEs is sharing the same CDM group with different OCC sequences or using orthogonal frequency resources, is more challenging because the UE is sharing the same resources for the PUSCH. Therefore, shifting the DMRS of one UE independently of the DMRS of other UEs will result in significant interference between different antenna ports used by different UEs. To address this challenge, several alternative solutions can be adopted as described below.

[0309] The UE may change the starting position of the PUSCH as long as one or more UL DMRS symbols of the PUSCH with the starting position selected by the UE occupy one or more of the same symbols as those of the UL DMRS of the old PUSCH or some of those symbols. For example, for PUSCH mapping type A with single-symbol DMRS having three additional DMRS positions, if the PUSCH duration is 12, 13, or 14, then the DMRS occupies the same symbols 1 0 , 5, 8, 11. Thus, for example, if the original PUSCH grant duration is 14 symbols and three additional DMRS are configured as shown in Figure 30 , then UE1 may attempt to access the channel starting from OS1 or 2, which results in the PUSCH with the starting position selected by the UE having durations equal to 13 and 12 symbols, respectively. For both PUSCH starting positions, the UL DMRS may occupy the same symbols as the UL DMRS of the originally scheduled PUSCH. In this case, even after changing the starting position of the PUSCH for UE1, the DMRS of UE1 and UE2 remain orthogonal.

[0310] This is not always the case, i.e., the UL DMRS occupies the same symbols for the PUSCH with the starting position selected by the UE and the originally scheduled PUSCH. Thus, according to another aspect, an index set S of OFDM symbols carrying the UL DMRS of the PUSCH with the new duration is to be selected from the set of symbol indices S old carrying the UL DMRS of the PUSCH with the old duration. If the two sets do not overlap and some of the indices belonging to S new do not belong to S new , then those indices are replaced with the closest indices in S old . Symbols in S old that are not used for transmitting the UL DMRS of the PUSCH with the new duration cannot be used to carry data to avoid conflicts with the DMRS of other UEs. old shows an example of a PUSCH grant with a duration equal to 12 symbols from OS 0 to OS11, where three additional DMRS are configured to occupy, i.e., S Figure 31 = {1 old , 5, 8, 11}. If UE1 attempts to access the channel starting from OS1 or OS2, this results in the PUSCH with the starting position selected by the UE having durations of 11 and 10, respectively. Unfortunately, within the duration of the PUSCH with the starting position selected by the UE, the UL DMRS must occupy the symbols S 0 = {1 new , 5, 8, 11} 0,6,9}, which means that only l 0 overlaps with the symbol carrying the UL DMRS of UE2. Also, the UE can use S with 5 and 8 respectively old to replace 6 and 9 in S with the closest indices in new to have S new ={l 0 ,5,6,8,9}. By doing so, the orthogonality between UE1 and UE2 is maintained.

[0311] To avoid extrapolating over many OFDM symbols, which would severely degrade the channel estimation 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 the PUSCH with the new duration, the index of the last OFDM symbol of the PUSCH can be used with the old duration. In the previous example of S old ={l 0 ,5,8,11} and S new ={l 0 ,6,9}, the UE can replace 6 and 9 in S new with 5 and 11 respectively to have S new ={l 0 ,5,6,11,9}, as shown in Figure 32 .

[0312] If PUSCH mapping type A is used, but the UE obtains the channel after l 0 , then PUSCH mapping type B can be used to map the DMRS according to the duration of the PUSCH with the starting position selected by the UE. If the set of symbol indices S new carrying the UL DMRS for the PUSCH with the new duration is different from the set of symbol indices assumed to carry the UL DMRS for the PUSCH with the old duration, then each element in S new is replaced with the closest element in S old . Figure 33 shows an example of a PUSCH grant equal to a duration of 12 symbols from OS 0 to OS 11, where three additional DMRSs are configured to occupy, i.e., S old ={l 0 ,5,8,11}. If UE1 fails to access the channel starting from OS0 but succeeds starting from OS7 (i.e., after l 0 ), then the DMRS can be mapped according to PUSCH mapping type B. Since the new PUSCH duration is five symbols, the UL DMRS can occupy the symbols indexed by l 0 ,4 relative to the PUSCH starting position OS7. Therefore, Snew＝ {7,11}. By comparing S new with S old , the UE can replace OS7 with OS8 to make S new＝ {8,11}.

[0313] If the UE accesses the channel in OS8, then the new duration of the PUSCH is 5, and according to the PUSCH mapping type B, and the symbol carrying the DMRS has an index of l 0 relative to the PUSCH, that is, S new ={8}. In this case, the last symbol in S old cannot be used to carry the DMRS, as shown in Figure 34 .

[0314] In addition, the UE can shift the entire scheduled PUSCH to a new starting position, and the scheduled DMRS can be shifted relative to the new starting position, rather than just starting the PUSCH transmission from the new starting position without shifting the entire PUSCH. For example, as shown in Figure 51 . Figure 52A Shows an example for the PUSCH, which is scheduled to be transmitted over 12 OFDM symbols from OS 0 to OS11, 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 OS2 shown in the figure, that is, the PUSCH starting position is shifted by two OFDM symbols. Then, the DMRS symbols are shifted by two OFDM symbols so that their new positions are OS 5 and OS11. Since the entire PUSCH is shifted, the UE can puncture / rate match the truncated symbols at the end of the authorized PUSCH.

[0315] Depending on the new starting position, if one or more of the UE's new shifted positions exceed the end of the scheduled PUSCH, then the UE can puncture one or more of the scheduled DMRS symbols. For example, Figure 52B shows an example of a UE that transmits only one DMRS symbol instead of the originally scheduled two DMRS symbols. The DMRS symbol is scheduled to be transmitted in OS 3, and the UE can transmit it in OS11. And the DMRS scheduled to be transmitted in OS 9 can be discarded.

[0316] For example, the UE may be configured to transmit at least one DMRS symbol in the first OFDM symbol of 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 cases where no scheduled DMRS symbol can be transmitted due to the shifted PUSCH, the higher layer signaling may indicate the minimum number of DMRS symbols, their positions, etc. Moreover, the UE may be configured such that if the remaining number of OFDM symbols carrying the PUSCH is less than a certain threshold, the UE may not transmit this PUSCH as it is most likely to be successfully decoded. Such a threshold may be indicated to the UE by higher layer signaling.

[0317] If PUSCH is not allowed to cross the slot boundary and the UE is scheduled with multiple consecutive PUSCHs, then each scheduled PUSCH cannot be shifted beyond the end of the slot starting from the slot containing the original scheduled PUSCH. For example, Figure 53A An example of N PUSCHs scheduled for the UE is shown, and three candidate starting positions are indicated for PUSCH 0. Then, based on the channel availability, PUSCH 0 can be shifted to start from any of the indicated candidate starting positions. 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 specific threshold indicated by the higher layer, then the UE can discard PUSCH 0. Then, the UE can attempt to access the channel to transmit the next PUSCH.

[0318] If the slot contains multiple PUSCHs, then the UE can shift all scheduled PUSCHs within the slot as shown, for example, Figure 53B In this figure, PUSCH 0 is discarded due to channel unavailability. Therefore, the UE can attempt to access the channel to transmit PUSCH 1. If the channel is not available, then PUSCH 1 and the subsequent PUSCH 2 will be shifted together to a new starting position. If any PUSCH reaches the end of the slot boundary, the OFDM symbols beyond the slot boundary will be punctured. Since the number of available OFDM symbols for this PUSCH is reduced, the UE can perform rate matching / puncturing of the data.

[0319] In addition, the UE shifts the PUSCH to a new starting position, but for example, the UE can keep the scheduled DMRS symbols at the positions indicated in the original grant as shown, Figure 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, Figure 54BAs shown in. If the new starting position of the PUSCH falls outside all scheduled DMRS symbols, then the UE may abort the transmission of the PUSCH. Alternatively, as mentioned above, the UE may be configured by higher layer signaling, for example, with a specific number of compensating DMRS symbols that can be transmitted, their positions, any other configurations, etc., and all scheduled DMRS symbols can be discarded by the UE. Figure 54C An example is shown where the PUSCH starting position is at OS10, where all previous DMRS symbols are discarded. In this case, the UE may transmit DMRS symbols in the first OFDM symbol of the PUSCH with the new starting position.

[0320] Power boost in the first PUSCH transmission

[0321] For the first PUSCH transmission in the UE's COT, the DMRS power is boosted relative to the DMRS in subsequent PUSCH transmissions within that COT. This ensures higher reliability in detecting the PUSCH at the gNB and improves the channel quality estimation. If the PUSCH transmission rate is matched to fewer resources or punctured due to delayed channel access, then this in turn improves the BLER on the PUSCH. This concept is shown in Figure 35 where the nominal power is boosted in the DMRS sequence of the first PUSCH transmission of the UE after CAT4 LBT.

[0322] As another use case, if the PUSCH transmission starts at a position where the UE discards one or more OSs carrying the DMRS sequence, then the UE may boost the power of the remaining DMRS sequence to improve the quality of channel estimation. Figure 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, thus compensating to some extent for the loss of the DMRS sequence in OS#0. Here, the gNB will detect the absence of DMRS on OS#0 and identify that the PUSCH did not start on OS#0. It identifies the DMRS on OS#3 and attempts to decode the PUSCH from the starting positions OS#1, 2, and 3.

[0323] Power boost value α DMRS-CAI Is configured for the UE by RRC signaling. This value may depend on the number of DMRS sequences actually transmitted in the available PUSCH resources.

[0324] Furthermore, after LBT of the UE, the power for PUSCH REs can be increased within the available PUSCH resources for the first PUSCH transmission within the COT for the UE. The increase can vary according to the number of available OSs. If the original grant has N OSs and the UE can only access K OSs, then the UE can increase the power of the PUSCH REs in the K OSs by a power boost factor P PUSCH，boost = 10 * log10(α PUSCH-CAI * N / K). Here, α PUSCH-CAI 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 can use a value of 1. The UE can apply the power boost only if there is a power margin with the given N and K. Otherwise, it can boost the power to the maximum possible value of the device P 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 can depend on the UE's capabilities and / or can be configured to the UE via RRC signaling). P PUSCH，nominal is the nominal power for transmitting the PUSCH transmission. The PUSCH transmissions after the first PUSCH transmission can use the P PUSCH，nominal power level.

[0325] DMRS sequence depending on the PUSCH start position

[0326] The UE can be configured via RRC signaling with multiple DMRS sequences, where the UE selects the DMRS sequence indicating the starting OS of the PUSCH. This concept is shown in Figure 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 the channel access right to OS#0, it will use DMRS transmission sequence #1, when the UE has the channel access right to OS#1, it will use DMRS transmission sequence #2, 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 method avoids the need to blindly detect the starting OS for PUSCH transmission.

[0327] The sequences can be defined by providing different initialization parameters for the candidate starting positions in the pseudo-random sequence generator. For example, a parameter n CAI can be introduced in the DMRS sequence, where n CAIVaries according to the starting position of the PUSCH. If transform precoding for the PUSCH is enabled, the reference signal sequence r(n) should be generated according to the following conditions:

[0328]

[0329] where is a low PAPR sequence, defined as follows: for PUSCH transmissions dynamically scheduled by DCI, δ = 1 and α = 0.

[0330] is defined by the cyclic shift α of the basic sequence according to the following formula

[0331]

[0332] where is the length of the sequence. Multiple sequences are defined by different values of ɑ and δ from a single basic sequence.

[0333] The basic sequence is divided into groups, where u ∈ {0, 1,..., 29} is the group number, and v is the basic sequence number within the group, such that each group contains each basic sequence of length 1 ≤ m / 2 δ ≤ 5 (v = 0) and each basic sequence of length 6 ≤ m / 2 δ (v = 0, 1).

[0334] The sequence group where is given by the following formula:

[0335] - If is configured by the higher layer parameter nPUSCH-Identity-Transform-precoding and the PUSCH is not a msg3 PUSCH

[0336] - Otherwise

[0337] where n CAI is defined as the parameter that identifies the starting position of the PUSCH

[0338] where f gh and the sequence number v are given by the following formula:

[0339] - If neither group hopping nor sequence hopping is used

[0340] f gh = 0

[0341] v = 0

[0342] - If group hopping is used instead of sequence hopping

[0343]

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

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

[0346]

[0347] where the pseudo - random sequence c(i) is a pseudo - random Gold sequence of length 31 and its generator shall be initialized at the start of each radio frame with ;

[0348] If transform precoding for PUSCH is not enabled, then the sequence r(n) shall be generated according to

[0349]

[0350] where the pseudo - random sequence c(i) is a pseudo - random Gold sequence of length 31 and its generator shall be initialized using

[0351]

[0352] where l is the number of OFDM symbols in a slot, the number of slots in a frame, and

[0353] -n SCID ∈ {0, 1} and is given by the higher - layer parameter UL - DMRS - Scrambling - ID (if provided) and PUSCH is not msg3 PUSCH

[0354] -n SCID = 0 and otherwise

[0355] where n CAI is defined as the parameter identifying the starting position of the PUSCH

[0356] The DMRS resource density in the first PUSCH transmission

[0357] The UE is RRC configured for a certain number of DMRS sequences for PUSCH transmission. According to another aspect, when the UE performs PUSCH transmission after successful LBT, the UE can use a different number of DMRS transmissions, i.e., the UE can use a different number of DMRS transmissions in the first PUSCH transmission of its COT. This enables the gNB to improve channel estimation and thus improve the BLER on the PUSCH when it is punctured or rate matched to fewer resources. The DMRS configuration for PUSCH after successful LBT can be configured via RRC signaling to the UE. As Figure 38 seen, compared to the next PUSCH transmission in the UE's COT, in the first PUSCH transmission after LBT, the density of the DMRS is higher and the time resources of the DMRS are different. Here, the UE has 2 UL grants of PUSCH type B and is RRC configured to transmit the DMRS in OS#{0,3,6,9} for the first PUSCH transmission and perform subsequent PUSCH transmissions in OS#{0,10}.

[0358] UL preamble to indicate a variable starting position

[0359] The UE can transmit a UL preamble to indicate the starting position of the first PUSCH after LBT. The position of the PUSCH resource relative to this preamble. For example, the PUSCH can start in the same OS as the preamble, as Figure 39 shown. 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 for the UE. The gNB monitors and detects the preamble; upon detecting it, the gNB finds the PUSCH in the same OS.

[0360] 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 the 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, then the DMRS is discarded and the preamble is transmitted.

[0361] In addition, as Figure 40 shown, 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 an offset from the lowest RB of the PUSCH as shown in Figure 40 A, or fixed relative to the center of the carrier as shown in Figure 40 B.

[0362] The preamble sequence is configured for the UE via RRC signaling. The sequence can be UE - specific configured or commonly configured across UEs.

[0363] When the UE is specifically configured, the preamble can have the same sequence as the DMRS of the PUSCH. The preamble can be applied only to the frequency resources of the PUSCH.

[0364] The preamble can be transmitted corresponding to DL RS such as SSB or CSI - RS or DMRS. For example, the preamble can have the same correspondence as the DMRS of the PUSCH after the preamble. Alternatively, the correspondence can be configured via RRC signaling to the UE.

[0365] In addition to indicating the start of PUSCH transmission, the preamble can also be used to indicate the duration of the UE's COT. A set of preambles can be configured for the UE. Each preamble can represent a certain duration of the COT. The UE can select the preamble to be transmitted according to its expected channel occupancy duration. For example, in autonomous UL transmission using configured grants, the gNB may not know how to expect PUSCH transmission from the UE without higher layer information such as BSR. To reduce latency, the PHY signaling via the preamble can indicate the duration of the use of the configured grant resources. This can help the gNB plan its resources after the UE's COT or enable efficient COT sharing between the UE and the gNB.

[0366] If the preamble sequence is common for multiple UEs, then the preamble can provide improved power efficiency and co - existence because other nodes can identify that the channel is occupied. If the preamble is common in DL and UL, then this promotes co - existence. The location of the preamble resources can be common in DL and UL. Rate matching can be performed on the PUSCH near the preamble, or the preamble can puncture the PUSCH.

[0367] For PUSCH mapping type B used for either SU - MIMO or MU - MIMO, the positions of the DMRS symbols are defined relative to the PUSCH resources. Thus, if the UE selects a PUSCH start position different from the originally scheduled position, then the UE can transmit (one or more) UL DMRS symbols according to PUSCH type B. In this case, the first DMRS symbol can occupy the first symbol of the PUSCH with the start position selected by the UE. According to the PUSCH type B DMRS mapping rule, the positions and number of additional DMRS symbols can be based on the duration of the PUSCH with the position selected by the UE. For example, Figure 49Shows an example of a PUSCH that is scheduled for transmission over 8 OFDM symbols from OS 5 to OS 12, with two additional UL DMRS 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), then the duration of the PUSCH with the starting position selected by the UE is 6 OFDM symbols. In this case, as Figure 49 shown in 0 , the UE can map the UL DMRS according to mapping type B over 6 OSs and with a new PUSCH duration of 4 relative to the start of the PUSCH.

[0368] Transmit the PUSCH in the available symbols

[0369] Some procedures are described above so that the gNB and the UE have the same understanding of which starting position the UE can try to access the channel in case the UE cannot access the channel at the start of the UL grant. Several methods are also described regarding how shifting the starting position affects the DMRS and how it can be used to indicate which PUSCH candidate position the UE selects. Procedures for puncturing, adapting the MCS, and how to transmit the carried UCI are described below.

[0370] Puncturing

[0371] As a simple procedure, after the UE generates a PUSCH based on the grant provided by the gNB, the UE can puncture some of those symbols without adjusting the UL DMRS position and transmit the other symbols. According to one aspect, the UE can puncture all the symbols from the start of the PUSCH grant to the symbol at which the user accesses the channel. Figure 41 Shows an example of a PUSCH grant with a duration equal to 12 symbols from OS 0 to OS 11, where three additional DMRSs are configured to occupy 0 , 5, 8, 11. If the UE accesses the channel starting from OS 7, then the UE can puncture OS 0 to OS 6.

[0372] In some cases, the remaining DMRSs may not be sufficient for the gNB to obtain an accurate channel estimate, especially if all the DMRS symbols are punctured, because the last two OFDM symbols in the PUSCH may not carry any DMRS at all. Therefore, according to another aspect, the minimum number of required DMRS symbols can be transmitted to obtain reliable decoding at the gNB. If the remaining DMRS symbols are fewer than this minimum threshold, then the UE can abandon the UL transmission to reduce power consumption, because it is less likely that the gNB can decode the transmitted PUSCH.

[0373] This threshold can be configured by a higher layer parameter such as an RRC parameter called min_DMRS_num, which can provide either the absolute number of the minimum required DMRS symbols or a fraction of the already scheduled DMRS symbols. Also, the minimum number of required DMRS symbols can 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 varying according to the scheduled MCS, where I MCS is the MCS in the case where a given DCI provides a PUSCH grant. Also, the MCS for i ∈ {1, …, N} can be provided by a higher layer parameter such as the RRC parameter min_DMRS_num th_i . If the higher layer parameter indicates that the MCS thresholds in any row are equal, i.e., MCS th_(i-1) = MCS th_i , then the minimum number of required DMRS symbols for the associated row in which both MCS thresholds appear is disabled.

[0374] Table 6 Minimum number of required DMRS symbols varying according to MCS

[0375]

[0376] Similarly, the minimum number of required DMRS symbols can vary according to the PUSCH duration as shown in Table 7, e.g., where L is the actual number of OFDM symbols that can be transmitted, and D for i ∈ {1, …, N} th_i can 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, i.e., D th_(i-1) = D th_i , then the minimum number of required DMRS symbols for the associated row in which both MCS thresholds appear is disabled.

[0377] Table 7 Minimum number of required DMRS symbols varying according to the actual number of OFDM symbols that can be transmitted by the UE

[0378] Also, puncturing can be used in the case of MU-MIMO scheduling to avoid loss of orthogonality between co-scheduled UEs. The UE can use only any scheduled DMRS symbols and can not attempt to adjust the UL DMRS based on the duration of the PUSCH with a newly selected starting position.

[0379] Adapting MCS

[0380] Assuming that the authorized TBS size is fixed and does not depend on the LBT result, the MCS associated with the scheduled PUSCH may not be an effective MCS for transmitting the entire TBS in one transmission. At the same time, if the UE autonomously changes the MCS of the relevant chain associated with the scheduled PUSCH based on the LBT result without a common understanding of the new MCS between the UE and the gNB, it will be a huge burden for the gNB to detect the MCS used.

[0381] If multiple PUSCH starting positions are signaled by multiple DCIs, as described above, then the correct MCS associated with the new PUSCH starting position can be signaled in these DCIs.

[0382] If multiple PUSCH starting positions are configured by higher layer parameters, then 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 the 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:

[0383] Table 8 New MCS varying according to the result of the old MCS and LBT

[0384]

[0385] Where L is the duration of the PUSCH provided in the UL grant according to the symbol, and I MCS is the MCS given in the PUSCH grant. Although I new,N(L-1) can vary according to I MCS , for example, I new,x = max{2I MCS , MCS_max} means that the new MCS is twice the MCS given in the PUSCH grant and has a certain maximum MCS labeled as MCS_max.

[0386] Alternatively, the UE can autonomously change the MCS and indicate the selected MCS by transmitting the carried UCI to the PUSCH. Moreover, the carried UCI can be transmitted at a specified position in the new PUSCH duration. For example, the carried 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 part in the PUSCH.

[0387] 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 relationship with the candidate MCSs. Therefore, the gNB can find out the selected MCS by knowing the DMRS initialization sequence. This can be achieved by signaling multiple values used to generate the DMRS initialization sequence by the following equation to implement.

[0388]

[0389] The additional values of to can 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.

[0390] Carried UCI transmission

[0391] If based on the LBT result or puncturing or shifting of PUSCH symbols, the carried UCI will be affected, especially if the UCI is mapped to the first few OFDM symbols at the start of the PUSCH grant. According to another aspect, if the UCI does not carry DMRS or immediately follows the first single-symbol / double-symbol DMRS transmission, then the UCI can have a higher priority than the PUSCH and can be transmitted in the first available symbol.

[0392] Because based on the LBT result, only a few OFDM symbols are available for UL transmission, there may not be enough resources to carry the UCI, especially if its size is large. Therefore, according to another aspect, specific priority rules can be defined to define what parts of the UCI can be discarded. For example

[0393] ● The priority of the CSI report in part 2 can be lower than that of the CSI report in part 1.

[0394] ● The priority of the CSI report in part 2 can be lower than the Ack / Nack feedback.

[0395] ● The priority of the CSI report in part 1 can be lower than the Ack / Nack feedback.

[0396] 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., Part 2 CSI report < Part 1 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.

[0397] Signal the CAI

[0398] 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.

[0399] PHY signaling of the CAI

[0400] Signaling via PDCCH in the common search space

[0401] In DL, NR DCI can carry a payload, and PDCCH can be used to signal the CAI in the physical layer.

[0402] 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 a 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.

[0403] 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 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. Figure 14 The method of detecting the CAI is described herein. Here, the gNB 2 and its UE are general nodes, and the gNB 1 transmits the CAI on the Cell 1 ​

[0404] In an NR-U cell performing carrier aggregation with a licensed PCell, the PCell may configure a CORESET for a sibling node to monitor DL-CAI-RNTI DCI on the NR-U cell. Alternatively, an SSB / RMSI signal may be present in an SCell to allow a general node to monitor CAI.

[0405] Type0B-PDCCH common search may be introduced for the DAI format, and this DCI format has a CRC scrambled by DL-CAI-RNTI for CAI. The association between the monitoring occasion for the Type0B-PDCCH common search space and the SS / PBCH block index may be the same as the association for the monitoring occasion for the Type0-PDCCH common search space. The UE may assume that the DM-RS antenna port associated with PDCCH reception in the Type0B-PDCCH common search space and the DM-RS antenna port associated with SS / PBCH reception are quasi-co-located with respect to delay spread, Doppler spread, Doppler frequency shift, average delay, and spatial Rx parameters. The values for initializing the DM-RS scrambling sequence may be set as follows.

[0406] ● It may be set to a fixed specification-defined constant

[0407] ● It may be set to the cell ID.

[0408] The length of the DCI based on 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, then the NR-U UE may discard monitoring of this DCI.

[0409] A higher layer parameter dlCAIPeriod may be defined to indicate the period for signaling CAI (as seen in Figure 10 and Figure 11 where the gNB in the MCOT may signal CAI multiple times via the CNB so that the listening node does not miss the signal).

[0410] Not all cells may support the transmission of CAI. A bit in the PBCH may indicate whether the cell supports CAI transmission.

[0411] Alternatively, the CAI can be multicast to a group of UEs. For example, a group common PDCCH (such as the PDCCH for DCI format 2_0) can be used to carry the CAI. UEs in the RRC connected state can decode the PDCCH as they will have the configuration of the GC-CAI-RNTI for the CAI. The DCI can be scrambled with the group common RNTI “GC-CAI-RNTI”.

[0412] It is advantageous for a node such as a gNB to indicate the start of channel access to the UE. This enables the UE to identify the presence of valid CSI-RS, DRS, SSB / PBCH, PRACH opportunities, and / or resources (configured grant resources) for COT sharing with the gNB.

[0413] The gNB can transmit DCI with DL-CAI-RNTI to the UE to provide COT status. The DCI can carry at most C bits indicating the COT of the gNB. C can be configured to the UE via RRC signaling or predefined in the specification. For example, for an MCOT of up to 10 ms, C = 4. The DCI can also carry the bandwidth over which the COT is valid, e.g., a bitmap of B bits corresponding to a 20 MHz subband B in the spectrum. The bits corresponding to the set of 20 MHz subbands that the gNB can access the channel are set to 1. In this case, if the UE receives DCI with both DL-CAI-RNTI and SFI-RNTI, then for the time slots where the CAI-RNTI indicates no channel access, it can ignore the SFI. Alternatively, the DCI can indicate the COT by specifying the time slot format for N time slots of the COT. The DL-CAI-RNTI can be the SFI-RNTI that provides the time slot format indication to the UE. In addition to the "D", "X", and "U" states in the time slot format being used to identify the DL, flexible, and UL states respectively, a "null" format can be introduced to identify invalid channel access. For example, the time slot format "NNNNNNNNNNNNNN" implies that no channel access is available on any of the 14 symbols of the time slot. A time slot format with partial channel access can also be defined, such as "XXXXXXXNNNNNNN", where channel access is not available on the last 7 symbols of the time slot as it is outside the COT of the node. Since the DCI can carry the time slot format for multiple time slots, when the symbol encounters the null format, the UE recognizes that the gNB has no channel access right and can ignore the SFI of the symbols after the null value. A second DCI with BW-RNTI (bandwidth-RNTI) can carry information on the 20 MHz subband over which the COT is valid. The BW-RNTI can be detected in the same CORESET and monitoring occasion as the SFI-RNTI; thus, the UE uses the SFI-RNTI and BW-RNTI to determine the bandwidth and time of the gNB's channel access. In the case of directional LBT, the COT can be different in different spatial directions. In this case, a single DCI can provide COT information for multiple spatial directions. Thus, the DCI can carry the TCI status for each COT it indicates. Alternatively, the DCI can carry the COT for D spatial directions configured to the UE. D can be provided via RMSI or OSI or configured in a UE-specific manner. Alternatively, the DCI received in a given spatial direction can 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 the DMRS of the DCI (carrying the COT) can indicate the COT in that spatial direction; here, the CA-RS is the DMRS of the DCI carrying the COT information.Therefore, the gNB can transmit multiple DCIs to indicate COTs in different spatial directions using different CA-RSs.

[0414] If the gNB has the channel access right for a given CA-RS, then the CA-RS-group can be defined as the set of RSes that can be transmitted by the gNB. For example, the CA-RS-group can be defined for the DMRS of the DCI carrying the COT and includes other RSes that can be transmitted by the gNB in a spatial direction similar to that of the DMRS, such as CSI-RS. If the UE has the authorization or RS belonging to the CA-RS-Group to which the gNB can access the channel, then the UE processes that authorization or RS. The gNB can perform spatial LBT in the direction given by the CA-RS. If successful, then the gNB can transmit the signals in the CA-RS-Group of that CA-RS. The CA-RS-Group should contain RSes with the same / similar spatial direction as the reference CA-RS in that CA-RS-group. As Figure 42 shown, the gNB transmits the DCI carrying the COT information on CA-RS1. When the UE receives this message, the UE identifies that it can only receive the signals in the spatial direction given by the RSes in the CA-RS-group of that COT's CA-RS 1 .

[0415] In addition, for directional LBT, if the gNB shares its COT with the UE, then the UE can perform the configured grant transmission on the shared COT only when the spatial direction of the configured grant corresponds to the DL spatial direction used for that COT. The UE can also perform CAT2 LBT to access the channel in the shared COT in the direction corresponding to the respective DL CA-RS. As Figure 43 shown, the UE transmits in the gNB's COT using the spatial direction corresponding to the DL CA-RS-Group used for the CA-RS 1 .

[0416] If a node such as a gNB obtains channel access from the start of a partial slot, it may only have channel access to the partial slot at the end of the COT. In this case, it cannot indicate the format of the last partial slot because this requires additional bits to indicate the COT with finer granularity. Unless the UE has a clear authorization 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 it does not receive a COT indication of a valid channel access, if the UE has an authorization, then the UE assumes that the channel access is valid and continues to process that slot. If an authorization is received during that COT, it can be used especially for scheduling authorization. However, for configured authorization, if a COT indication of a valid channel access is not received for a partial slot, then the UE assumes that the channel access is invalid and does not transmit in that slot.

[0417] The UE can monitor the CAI only on selected resources to maintain low power consumption during the CAI monitoring duration. For example, the UE can perform a periodic S CAI Monitor the CAI on the CORESET in the narrow BWP in the search space. After receiving the CAI, the UE can switch to a pre-configured wider BWP and monitor the configured CORESET for control information.

[0418] As an alternative, the UE can monitor its CAI and control information after receiving the CAI on the common BWP, but different search spaces can be configured to monitor the CAI and other control information.

[0419] Alternatively, for the remaining duration of the COT detected from that CAI, the search space configured for the CAI is automatically disabled when the CAI is detected.

[0420] Signaling via the PDCCH to trigger a handshake

[0421] In the DL, the NR DCI can carry a payload for CAI-1 to trigger a handshake on the UL. This can occur in the following ways.

[0422] ● The PDCCH for CAI-1 can be signaled using the C-RNTI or CS-RNTI. The UE blindly decodes the PDCCH and, if its LBT is successful, responds with the CAI-R. The CAI-I can also indicate the type of LBT that the UE must perform before transmitting the CAI-R. This method is shown in Figure 15 . In this case, other UEs attached to the same cell and nodes outside that cell cannot receive CAI-1.

[0423] The trigger can be sent in the UE-specific search space or the Type0-PDCCH common search space as part of the DL or UL grant. One or more of the following fields can be used to introduce new DCI formats 1_1C, 1_0C, 0_1C, 0_0C.

[0424] ○ 1 bit indicating the need for a handshake

[0425] ○ L bits indicating the type of LBT to be performed by the UE, priority class

[0426] ○ D bit for T OCC , indicating the channel occupancy time so that the UE can signal its CAI-R to its gNB in that cell. OCC within T of its gNB in that cell.

[0427] ○ H bit indicating the threshold for sensing before CAI-R transmission

[0428] The PDCCH for CAI-1 can be signaled in the common search space with CAI-RNTI in a search space such as the Type0 common PDCCH search space. The CAII-RNTI can be configured via the RMSI or a constant value given in the specification. Multiple sibling nodes can receive the DCI, and one or more UEs can send their CAI-R according to how the CAI-I configures the trigger. General nodes from other NR-U cells can also detect CAI-1 and obtain T from it. OCC . The DCI can also have an L bit to indicate the type of LBT to be performed by the triggered UE. The CAI-R will contain the implicit or explicit identity of the receiver so that the receiver can identify the sender of the CAI-R. The CAI-R can also contain the identity of the node requesting the handshake – this can be useful in D2D or V2X applications where multiple nodes can access resources via frequency / time multiplexing; thus multiple CAI-Is and CAI-Rs can be transmitted and their senders and receivers should be identifiable. The trigger can be provided in the following ways.

[0429] ● Receiving the CAII-RNTI implicitly triggers a handshake. The trigger starts at time T from receiving CAI-I. Resp The UE that receives the DL or UL grant within T transmits the CAI-R. As Figure 16 shown in 1 the UE Resp receives CAI-1 and the DL grant within the time T of CAI-1. Therefore, if the CCA / LBT of the UE 1 is successful, then it will respond with the CAI-R.

[0430] ● Similar to P-RNTI, CAII-RNTI can provide PDSCH authorization, which carries the ID (such as C-RNTI) of the UE that must respond with CAI-R. The UE that finds its ID in the message sends CAI-R. Since the message has to be processed by the higher layers, this method incurs some inherent latency.

[0431] ● 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 method makes the payload in DCI huge.

[0432] Signaling CAI-R via RACH

[0433] Apart from indicating that the channel of the node is clear for reception, the CAI-R response cannot carry much information. Therefore, the PRACH preamble is a good candidate for CAI-R. The RACH preamble for CAI-R can be configured by RRC for the UE. 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 preamble, multiple CAI-Rs can be received simultaneously. After the preamble reception, the handshake is completed and the gNB continues to perform DL / UL authorization for the UE.

[0434] Signaling UL CAI-R on PUCCH

[0435] The short PUCCH format for SR can be used for CAI-R. When the gNB detects energy in the CAI-R resource of the UE, it assumes that CAI-R has been received and the handshake has been completed.

[0436] CAI-R can include additional information, such as the energy level detected during CCA / LBT at the UE. Additionally, it can carry the 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 via RACH. Short PUCCH or long PUCCH can be used for CAI-R.

[0437] CAI-Rs from multiple UEs can be orthogonally multiplexed or multiplexed with other PUCCH signals from other UEs.

[0438] Preamble-assisted CAI

[0439] The preamble can be used to indicate CAI. It can carry an indication of T OCCSome or all of the information required by the cell using the channel. Additionally, it can indicate resources where more information about the occupancy can be obtained. Such a design can enable nodes from other cells and technologies to simply detect the preamble without having to obtain the SI of the NR-U node occupying the channel. Nodes monitor the preamble over time and look for a high correlation with a known preamble. When the correlation exceeds a threshold, the preamble is detected.

[0440] A common preamble can be used across all NR-U nodes to simplify the detection for general nodes. The preamble can be a ZC sequence on the DL or based on an m-sequence (such as PSS or SSS) or based on an RS sequence (such as CQI-RS). On the UL, it can be a PRACH or SRS-like sequence.

[0441] Cell coloring

[0442] The preamble can carry S bits of information that indicate the cell transmitting the CAI. The S bits can be derived from the cell ID of the gNB or UE connected to that cell ID. If S is small (e.g., 2 or 3 bits), then the listening node needs to correlate with a small set of known sequences of possible preambles (4 or 8 for 2 or 3 bits). The S bits provide "cell coloring" which enables the listening node to identify whether the transmission is within its cell or outside its cell. If the number of bits indicated is less than the number of cell IDs, there is some ambiguity in identifying the cell in which the preamble is transmitted; thus, a general node cannot know whether it is from its own cell, but it can quickly identify the CAI from many cells. To resolve the ambiguity, additional information can be attached to the preamble, but nodes that identify the transmission as being from a different cell do not need to look for this information. The method of detecting the preamble is shown in Figure 17 If complete information about the cell ID is available, nodes within that cell can use a higher threshold for LBT failures and allow spatial multiplexing.

[0443] Indicate T on the preamble OCC

[0444] The S bits of the preamble can be used to indicate T OCC . General nodes will know the state of the channel and when they should start sensing the channel.

[0445] Indicate the S bits on the preamble

[0446] The S bits can be indicated in one of the following ways. Generally, if the preamble has the ability to indicate the S bits, then it can be split between indicating T OCC and cell coloring.

[0447] ● For ZC-based preambles, the S bits can be used as part of the root or cyclic shift

[0448] ● The S-bit can be used as part of the initialization for the m-sequence based preamble.

[0449] ● Preamble sequence p can be repeated S times in time; an OCC vector of length S w can be applied to the S repetitions to carry S-bit information. Here, the preamble is repeated 4 times and w = [w 0 w 1 w 2 w 3 T ​ .

[0450] Figure 18 (A) shows an example of how to repeat the transmission of the preamble in time. The preamble can be transmitted asynchronously – so Node 1 transmits it immediately after successfully completing the LBT. After transmitting the preamble, it can transmit a certain reservation signal to synchronize with the symbol boundary.

[0451] Figure 18 (B) shows an example of transmitting the preamble synchronously with the symbol boundary. After a successful LBT, there is a reservation signal. After starting the symbol boundary, the preamble is transmitted.

[0452] Preamble resource

[0453] The CAI preamble can be narrowband so that the receiving node can detect it with minimum power consumption. Its bandwidth can be less than the minimum BWP supported in NR-U, e.g., 5 MHz for FR1. Since the ETSI harmonization standard for 5 GHz requires the use of 20 MHz channels and also allows operation in a smaller band (as small as 5 MHz) centered on the 20 MHz band, the selection of 5 MHz for the CAI preamble can be good for coexistence with WiFi. If the preamble meets the minimum OCB requirement, i.e., 80% of 5 MHz, then it may be sufficient.

[0454] The preamble can be transmitted at a predefined location in the unlicensed band (such as the center of the 20 MHz band) or at a specific predefined location (such as the raster position) so that the general node can identify its location. An Figure 19 example is shown in which the 80 MHz band is channelized into 20 MHz bands and the CAI preamble can be transmitted at the center 5 MHz.

[0455] The resources for CAI can be configured by RRC and indicated by SI so that all UEs can locate the CAI. In CA, the information can be provided by the PCell. In DC, the information can be provided by the MCG or obtained from the SI carried in the DRS or SSB. In SA, this information can also be obtained from the SI carried in the DRS or SSB. The SI can provide the frequency resources as an offset from the lowest PRB of the CBW.

[0456] Since NR supports operation in a wider bandwidth, an NR-U node can use multiple 20 MHz bands to create a composite carrier with a larger bandwidth in a single cell. (Instead of carrier aggregation that aggregates many SCell together, many bandwidth blocks are combined into a cell). In this case, this document also proposes to transmit the preamble at the center of each 20 MHz sub-band of the aggregated band. As Figure 20 shown, 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, the CAI preamble can be sent at the center of each 20 MHz channel, so that a general node in each 20 MHz channel can detect the status of the channel without having to switch frequencies.

[0457] Alternatively, the gNB can provide a bitmap in the SI or dynamically (by authorization, especially when a handshake is triggered) to indicate which 20 MHz band carries the CAI.

[0458] The numerology of the preamble can be determined as follows:

[0459] ● The preamble uses a pre-defined numerology based on the band. For example, 15 KHz for FR1 enables UEs with different processing capabilities to receive this signal. 30 KHz and 60 KHz can also be used because this can keep the latency caused by the CAI preamble small and allow for more repetitions with the coverage code.

[0460] ● The preamble uses the same numerology as the SSB. In this case, the listening node is required to know the numerology for the SSB or the NR-U cell either by performing initial access or through configuration from the PCell or PSCell.

[0461] Generally speaking, the information that can be sent on the preamble is limited. Therefore, this document proposes to use the preamble in combination with other forms of transmitting the CAI (such as PDCCH, RACH, and RS). The preamble can indicate the timing and resources where the remaining information of the CAI can be received. In other words, if the preamble information is relevant to a node, then the node will wake up to find the remaining CAI information, as Figure 17 seen. The remaining information of the CAI can appear in the first timing (of the signal type) after the preamble, or in the first N timings after the preamble. For example, if the remaining information is transmitted on the PDCCH, then the node can look for this information in the first monitoring timing after the preamble. This concept is in Figure 44is shown, where the UE monitors DL signals to obtain a preamble. After finding the preamble, it decodes the DCI carrying COT information in its PDCCH monitoring occasion.

[0462] Another example is shown in Figure 45 where a preconfigured CORESET and monitoring occasion are provided immediately after the preamble to save resources. If there are multiple symbols between the preamble and the next monitoring occasion, then the gNB cannot indicate the COT information or cannot perform scheduling for the UE immediately, and resources may be wasted. Instead, the CORESET and search space monitoring occasion can be provided with a minimum latency after the preamble. This control resource can be aperiodic, i.e., its presence is defined by the position of the preamble.

[0463] The aperiodic CORESET / search space monitoring occasion can be in the same OS as the Figure 46 shown preamble. Since it reduces the latency between the preamble and the DCI, it allows for better resource utilization.

[0464] The preamble and DMRS of the DCI carrying COT information can be QCL signals. Thus, when the UE receives the preamble in a certain spatial direction, it expects to receive the aperiodic CORESET in that direction as well, i.e., the aperiodic CORESET has the same QCL as the preamble. The gNB transmits the preamble multiple times in different spatial directions, as shown in Figure 47 to cover all UEs. The aperiodic CORESET is configured via RRC signaling. The monitoring occasion associated with this CORESET is defined as aperiodic, e.g., the search space monitoring occasion occurs only once in relation to the detected preamble. This search space is configured for 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.

[0465] In addition, the preamble can be in the form of the DMRS of the PDCCH in the CORESET. The gNB can schedule the preamble in the form of a wideband DMRS to provide sufficient reliability.

[0466] It should be understood that any one or all of the apparatuses, systems, methods, and processes described herein can be implemented in the form of computer-executable instructions (e.g., program code) stored on a computer-readable storage medium, which instructions, when executed by a processor (such as Figure 21B and 21FWhen executed by the processor 118 or 91), it causes the processor to execute and / or implement the systems, methods, and processes described herein. Specifically, any of the steps, operations, or functions described herein can be implemented in the form of such computer-executable instructions that are executed on a processor of a device or computing system configured for wireless and / or wired network communication. A computer-readable storage medium includes volatile and non-volatile, removable and non-removable media implemented in any non-transitory (e.g., tangible or physical) method or technology for storing information, but such computer-readable storage medium does not include signals. A computer-readable storage medium includes, but is not limited to, RAM, ROM, EEPROM, flash memory or other memory technologies, CD-ROM, digital versatile disk (DVD) or other optical disk storage devices, magnetic cassette tapes, magnetic tapes, magnetic disk storage or other magnetic storage devices, or any other tangible or physical medium that can be used to store the desired information and can be accessed by a computing system.

[0467] In describing the preferred embodiments of the subject matter of the present disclosure, specific terms are used for clarity as shown in the figures. However, the claimed subject matter is not intended to be limited to the specific terms 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.

[0468] This written description uses examples to disclose the invention, including the best mode, and also enables any person skilled in the art to practice the invention, including making and using any device or system and performing any combined method. The patent 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 are not different from the literal language of the claims, or if they include equivalent elements that are not substantially different from the literal language of the claims, then they are intended to be within the scope of the claims.

Claims

1. A wireless transmit / receive unit (WTRU) includes a processor, wherein the processor is configured to: Execute a first channel access procedure for listen-before-talk (LBT); Receive downlink control information (DCI), wherein the DCI indicates a second channel access procedure for LBT; and Execute the second channel access procedure for the LBT.

2. The WTRU according to claim 1, wherein the DCI is associated with a cell radio network temporary identifier (C-RNTI) or a slot format indicator radio network temporary identifier (SFI-RNTI).

3. The WTRU according to claim 1, wherein the DCI includes an indication of a channel occupancy time (COT).

4. The WTRU according to claim 1, wherein the DCI includes a slot format indicator (SFI).

5. The WTRU according to claim 4, wherein the SFI indicates that one of uplink, downlink, or flexible channel access is available for a time slot.

6. The WTRU according to claim 5, wherein the WTRU is configured to determine that uplink channel access is not available in the time slot based on the SFI indicating that downlink channel access is available for the time slot.

7. The WTRU according to claim 5, wherein the WTRU is configured to determine that uplink channel access is available in the time slot based on the SFI indicating that uplink or flexible channel access is available for the time slot.

8. The WTRU according to claim 1, wherein the processor is further configured to receive radio resource control (RRC) signaling, wherein the RRC signaling indicates the number of bits associated with an indication of a channel occupancy time (COT).

9. The WTRU according to claim 1, wherein the processor is configured to: Receive an uplink grant.

10. The WTRU according to claim 9, wherein the processor is configured to: Transmit a transmission according to the uplink grant.

11. A method performed by a wireless transmit / receive unit (WTRU), the method comprises: Executing a first channel access procedure for listen-before-talk (LBT); Receiving downlink control information (DCI), wherein the DCI indicates a second channel access procedure for LBT; and Executing the second channel access procedure for the LBT.

12. The method according to claim 11, wherein the DCI is associated with a cell radio network temporary identifier (C-RNTI) or a slot format indicator radio network temporary identifier (SFI-RNTI).

13. The method according to claim 11, wherein the DCI includes an indication of a channel occupancy time (COT).

14. The method according to claim 11, wherein the DCI includes a slot format indicator (SFI).

15. The method according to claim 14, wherein the SFI indicates that one of uplink, downlink, or flexible channel access is available for a time slot.

16. The method according to claim 15, wherein the WTRU is configured to determine that uplink channel access is not available in the time slot based on the SFI indicating that downlink channel access is available for the time slot.

17. The method according to claim 15, wherein the WTRU is configured to determine that uplink channel access is available in the time slot based on the SFI indicating that uplink or flexible channel access is available for the time slot.

18. The method according to claim 11, further comprising receiving radio resource control (RRC) signaling, wherein the RRC signaling indicates the number of bits associated with an indication of channel occupancy time (COT).

19. The method according to claim 11, further comprising receiving an uplink grant.

20. The method according to claim 19, further comprising transmitting a transmission according to the uplink grant.

21. A base station comprising a processor, wherein the processor is configured to: send a channel access indicator (CAI) initiation message to a user equipment (UE); receive a CAI response from the UE; and send an uplink grant to the UE, wherein the uplink grant indicates transmission resources on a channel associated with the CAI initiation message.

22. The base station according to claim 21, wherein the CAI initiation message includes a handshake request from the UE.

23. The base station according to claim 21, wherein the processor is further configured to: determine that a channel associated with the CAI initiation message is available at the UE based on the CAI response.

24. The base station according to claim 21, wherein the processor is configured to send the CAI initiation message at a time point synchronized with an orthogonal frequency division multiplexing (OFDM) symbol boundary.

25. The base station according to claim 21, wherein the CAI response includes an indication of a detected energy level associated with the channel.

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