Method for supplementary uplink access in a wireless system - Patents.com

Abstract

A method for supplementary uplink access in a wireless system is provided. [Solution] A method performed by a WTRU may include transmitting a first random access preamble on a first PRACH resource of a first UL carrier to a gNB and determining that the transmission on the first PRACH resource is unsuccessful. The method may further include determining that a maximum number of random access retransmissions on the first UL carrier is met, and in response, the WTRU transmitting a third random access preamble on a third PRACH resource to the gNB via a second UL carrier. The WTRU may determine a RA-RNTI for the second UL carrier at least in part by a carrier offset. The WTRU may monitor for a RAR based on the RA-RNTI.

Description

[Technical Field]

[0001] The present invention relates to a method for supplementary uplink access in a wireless system, and more particularly to a method for supplementary uplink access in a wireless system performed by a WTRU. [Background technology]

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 586,537, filed November 15, 2017, and U.S. Provisional Patent Application No. 62 / 591,482, filed November 28, 2017, the contents of which are incorporated herein by reference. Summary of the Invention

[0003] The method performed by the WTRU may include transmitting a first random access preamble (RA preamble) on a first physical RA channel (PRACH) resource of a first uplink (UL) carrier to a next generation Node B (gNB). The WTRU may determine that the transmission is unsuccessful, and in response, the WTRU may transmit a second random access preamble on a second PRACH resource on the first UL carrier to the gNB. If the transmission is unsuccessful, the WTRU may determine whether a maximum number of RA retransmissions has been met for the first UL carrier. If so, the WTRU may transmit a third RA preamble on a third PRACH resource to the gNB via the second UL carrier. The WTRU may determine an RA-RNTI for the second UL carrier at least in part by the carrier offset. The WTRU may monitor a random access response (RAR) based on the RA-RNTI. The first UL carrier and the second UL carrier may be separate UL carriers.

[0004] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, in which reference characters indicate like elements and in which: [Brief explanation of the drawings]

[0005] [Figure 1A] FIG. 1 is a system diagram illustrating an example communication system in which one or more embodiments may be implemented. [Figure 1B] 1B is a system diagram illustrating an example WTRU (Wireless Transmit / Receive Unit) that may be used within the communication system illustrated in FIG. 1A according to one embodiment. [Figure 1C]1B is a system diagram illustrating an exemplary RAN (Radio Access Network) and an exemplary CN (Core Network) that may be used within the communication system illustrated in FIG. 1A according to one embodiment. [Figure 1D] FIG. 1B is a system diagram illustrating a further exemplary RAN and a further exemplary CN that may be used within the communication system illustrated in FIG. 1A according to one embodiment. [Figure 2] 1 is a diagram of multiple carriers that a WTRU may use to communicate with a next generation Node B (gNB). [Figure 3] FIG. 1 is a diagram of multiple bandwidth portions configured by a bandwidth range. [Figure 4] FIG. 1 is a diagram of an exemplary MAC (Media Access Control) CE (Control Element) command. [Figure 5A] This is the logical representation of a 3-bit RV (redundancy version) counter. [Figure 5B] FIG. 5B is a state diagram illustrating the 3-bit RV counter of FIG. 5A. [Figure 6] 10 is a flowchart of a WTRU initiated random access (RA) procedure. [Figure 7] 10 is a flowchart illustrating an example method for determining whether to switch to a supplementary uplink (SUL) carrier for an RA. [Figure 8] 1 is a flowchart of an exemplary procedure for transmitting a scheduling request (SR). [Figure 9] A timing diagram illustrating an RA transmission on a bandwidth portion on a RUL carrier followed by an RA transmission on a bandwidth portion on a SUL carrier. DETAILED DESCRIPTION OF THE INVENTION

[0006] 1A illustrates an example communication system 100 in which one or more embodiments may be implemented. The communication system 100 may be a multiple-access system that provides content, such as voice, data, video, messaging, broadcast, etc., to multiple wireless users. The communication system 100 may enable the multiple wireless users to access such content through sharing of system resources, including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal frequency division multiple access (OFDMA), single-carrier FDMA (SC-FDMA), zero-tail unique-word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, filter bank multicarrier (FBMC), etc.

[0007] 1A, communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RANs 104 / 113, CNs 106 / 115, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although it will be understood that embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, any of the WTRUs 102a, 102b, 102c, 102d may be referred to as a “station” and / or “STA,” may be configured to transmit and / or receive wireless signals, and may include a UE (user equipment), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular phone, a PDA (personal digital assistant), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an IoT (Internet of Things) device, a watch or other wearable, an HMD (head mounted display), a vehicle, a drone, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of an industrial and / or automated processing chain), a consumer electronics device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be referred to interchangeably as a UE.

[0008] Additionally, the communications system 100 may include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communications networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNodeB, a home Node B, a home eNodeB, a gNB, a NR NodeB, a site controller, an access point (AP), a wireless router, etc. While the base stations 114a, 114b are each depicted as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0009] The base station 114a may be part of the RAN 104 / 113, which may further include other base stations and / or network elements (not shown), such as, for example, a base station controller (BSC), a radio network controller (RNC), relay nodes, etc. The base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as a cell (not shown). The frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide coverage for wireless services over a particular geographic area, which may be relatively fixed or may change over time. Furthermore, a cell may be divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple output (MIMO) technology and may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0010] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., RF (radio frequency), microwave, centimeter wave, micrometer wave, IR (infrared), UV (ultraviolet), visible light, etc.). The air interface 116 may be established using any suitable RAT (radio access technology).

[0011] More specifically, as mentioned above, the communication system 100 may be a multiple-access system and may employ one or more channel access schemes, such as, for example, CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115 / 116 / 117 using, for example, wideband CDMA (WCDMA). 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 ​​Ultra-Low Packet Access (HSUPA).

[0012] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may establish the air interface 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro), and may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA).

[0013] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may establish the air interface 116 using New Radio (NR) and may implement a radio technology such as NR radio access.

[0014] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may simultaneously implement LTE radio access and NR radio access, e.g., using dual connectivity (DC) principles. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0015] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless technology such as, for example, IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000EV-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), GERAN (GSM EDGE), etc.

[0016] 1A can be, for example, a wireless router, a Home Node B, a Home eNode B, or an access point and may utilize any suitable RAT to facilitate wireless connectivity in a local area such as, for example, a business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a roadway, etc. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as, for example, IEEE 802.11 to establish a wireless local area network (WLAN). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as, for example, IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or a femtocell. As shown in FIG. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106 / 115.

[0017] The RAN 104 / 113 may be in communication with the CN 106 / 115 and may be any type of network configured to provide voice, data, application, and / or voice over internet protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have various quality of service (QoS) requirements, such as, for example, different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions, such as user authentication. 1A, it will be understood that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs employing the same RAT or a different RAT than the RAN 104 / 113. For example, the CN 106 / 115, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, may also be in communication with another RAN (not shown) employing GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0018] Additionally, the CN 106 / 115 may serve as a gateway for the WTRUs 102a, 102b, 102c, 102d 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 that use common communication protocols, such as transmission control protocol (TCP), user datagram protocol (UDP), and / or IP in the TCP / IP Internet Protocol suite. The network 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs, which may employ the same RAT as the RAN 104 / 113 or a different RAT.

[0019] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with separate wireless networks over separate wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a, which may employ a cellular-based radio technology, and with a base station 114b, which may employ an IEEE 802.11 radio technology.

[0020] 1B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a GPS (Global Positioning System) chipset 136, and / or other peripherals 138. It will be understood that the WTRU 102 may include any sub-combination of the above elements while remaining consistent with an embodiment.

[0021] The processor 118 may be a general-purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors in conjunction with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any of other types of integrated circuits (ICs), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to a transceiver 120, which may be coupled to a transmit / receive element 122. While FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0022] The transmit / receive element 122 may be configured to transmit or receive signals to a base station (e.g., base station 114a) over the air interface 116. For example, in one 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 an emitter / 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 / or receive both RF and optical signals. It will be understood that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0023] 1B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO techniques. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0024] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As mentioned above, the WTRU 102 may have multi-mode capabilities. Thus, for example, the transceiver 120 may include multiple transceivers to enable the WTRU 102 to communicate over multiple RATs, such as NR and IEEE 802.11.

[0025] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light-emitting diode (OLED) display unit). Furthermore, the processor 118 may output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. Additionally, the processor 118 may access information and store data in any suitable type of memory, such as non-removable memory 130 and / or removable memory 132. The non-removable memory 130 may include random-access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In other embodiments, the processor 118 may access information and store data in memory that is not physically located in the WTRU 102, such as in a server or host computer (not shown).

[0026] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control power to other components in the WTRU 102. The power source 134 may be any device suitable for providing power to the WTRU 102. For example, the power source 134 may include one or more dry batteries (e.g., NiCd (nickel cadmium), NiZn (nickel zinc), NiMH (nickel metal hydride), Li-ion (lithium ion), etc.), solar cells, fuel cells, etc.

[0027] Additionally, the processor 118 may be coupled to a GPS chipset 136 that 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 from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals being received from two or more neighboring base stations. It will be understood that the WTRU 102 may obtain location information through any suitable location-determination method while remaining consistent with an embodiment.

[0028] Additionally, the processor 118 may be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photos and / or videos), a Universal Serial Bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth® module, a frequency modulated FM (FM) radio unit, a digital music player, a media player, a video game player module, an internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The peripheral device 138 may include one or more sensors, which may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, a direction sensor, a proximity sensor, a temperature sensor, a time sensor, a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0029] The WTRU 102 may include a full-duplex radio where the transmission and reception of some or all of the signals (e.g., associated with a particular subframe for both the UL (e.g., for transmission) and downlink (e.g., for reception)) may be parallel and / or simultaneous. The full-duplex radio may include an interference management unit 139 to reduce and or substantially eliminate self-interference either by hardware (e.g., a choke) or by signal processing by a processor (e.g., by a separate processor (not shown) or by processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio where the transmission and reception of some or all of the signals (e.g., associated with a particular subframe for either the UL (e.g., for transmission) or downlink (e.g., for reception)) may be half-duplex.

[0030] 1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As mentioned above, the RAN 104 may employ E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. Additionally, the RAN 104 may be in communication with the CN 106.

[0031] The RAN 104 may include eNode-Bs 160a, 160b, and 160c, although it will be understood that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, and 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, and 160c may implement MIMO technology. Thus, for example, the eNode-B 160a may use multiple antennas to transmit and / or receive wireless signals to the WTRU 102a.

[0032] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, etc. As shown in FIG. 1C, the eNode-Bs 160a, 160b, 160c may communicate with each other via an X2 interface.

[0033] 1C may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the above elements is depicted as part of the CN 106, it will be understood that any of the just-mentioned elements may be owned and / or operated by an entity other than the CN operator.

[0034] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an 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, activating / deactivating bearers, selecting a particular serving gateway during initial attachment of the WTRUs 102a, 102b, 102c, etc. The MME 162 may provide a control plane function for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0035] The SGW 164 may be connected to each of the eNode Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. In general, the SGW 164 may route and forward user data packets to the WTRUs 102a, 102b, 102c. The SGW 164 may perform other functions such as, for example, anchoring the user plane during inter-eNode B handovers, triggering paging when DL data is available to the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, etc.

[0036] The SGW 164 may be connected to a PGW 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.

[0037] The CN 106 may facilitate communication with other networks. For example, the CN 106 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, 102c and traditional landline communication devices. For example, the CN 106 may include or communicate with an IP gateway (e.g., an IMS (IP Multimedia Subsystem) server) that serves as an interface between the CN 106 and the PSTN 108. In addition, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0038] Although the WTRU is described in Figures 1A-1D as a wireless terminal, it is anticipated that in certain representative embodiments, such a terminal may use a wired communication interface (e.g., temporarily or permanently) with the communication network.

[0039] In a representative embodiment, the other network 112 may be a WLAN. A WLAN in infrastructure Basic Service Set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have access or an interface to a distribution system (DS) or another type of wired / wireless network that carries traffic into and out of the BSS. Traffic to a STA originating from outside the BSS may arrive through the AP and be delivered to the STA. Traffic originating from a STA to a destination outside the BSS may be sent to the AP and delivered to the respective destination. Traffic between STAs within a BSS may be sent through the AP, for example, where a source STA may send traffic to the AP, and the AP may deliver the traffic to the destination STA. Traffic between STAs within a BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent between (e.g., directly between) source and destination STAs via a direct link setup (DLS). In one exemplary embodiment, the DLS may use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using an Independent BSS (IBSS) mode may not have an AP, and STAs within or using an IBSS (e.g., all STAs) may communicate directly with each other. The IBSS mode of communication may sometimes be referred to herein as an "ad hoc" mode of communication.

[0040] When using the 802.11ac infrastructure mode of operation or a similar mode of operation, an AP may transmit beacons on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., a 20 MHz wide bandwidth) or a width that is dynamically set by signaling. The primary channel may be the operating channel of the BSS and may be used by STAs to establish a connection with the AP. In one exemplary embodiment, CSMA / CA (Carrier Sense Multiple Access / Collision Avoidance) may be implemented in an 802.11 system, for example. With CSMA / CA, STAs (e.g., every STA), including the AP, may sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a particular STA, the particular STA may back off. One STA (e.g., only one station) may transmit in a given BSS at any given time.

[0041] For example, a HT (high throughput) STA may use a 40 MHz wide channel for communication by combining a 20 MHz primary channel with adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0042] A Very High Throughput (VHT) STA may support channels of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz width. A 40 MHz and / or 80 MHz channel may be constructed by combining contiguous 20 MHz channels. A 160 MHz channel may be constructed by combining eight contiguous 20 MHz channels or by combining two non-contiguous 80 MHz channels, which may result in an 80+80 configuration. For the 80+80 configuration, after channel encoding, the data may pass through a segment parser, which may split the data into two streams. IFFT (inverse fast Fourier transform) processing and time-domain processing may be performed separately for each stream. The streams may be mapped onto two 80 MHz channels, and the data may be transmitted by the transmitting STA. At the receiver of the receiving STA, the operations for the 80+80 configuration described above may be reversed and the combined data may be sent to the MAC (Media Access Control).

[0043] Sub-1 GHz modes of operation are supported by 802.11af and 802.11ah. The operating bandwidths of the channels and carriers are reduced in 802.11af and 802.11ah compared to those used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TVWS (TV White Space) spectrum, while 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to representative embodiments, 802.11ah may support Meter Type Control / Machine-Type Communication, such as for MTC devices in macro coverage areas. MTC devices may have limited capabilities, including support (e.g., only support) for some and / or limited bandwidths. An MTC device may include a battery with a battery life that exceeds a threshold (eg, to maintain a very long battery life).

[0044] A WLAN system that may support multiple channels and channel bandwidths, such as 802.11n, 802.11ac, 802.11af, and 802.11ah, includes a channel that may be designated as a primary channel. The primary channel may have a bandwidth equal to the largest common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel may be set and / or limited by the STA that supports the smallest bandwidth operating mode among all STAs operating in the BSS. In the example of 802.11ah, the primary channel may be 1 MHz wide for a STA (e.g., an MTC-type device) that supports (e.g., only supports) the 1 MHz mode, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or NAV (Network Allocation Vector) setting may depend on the state information of the primary channel. If the primary channel is busy, for example, due to a STA (that only supports a 1 MHz mode of operation) transmitting to the AP, the entire available frequency band may be considered busy even though most of the frequency band may remain idle and available.

[0045] In the United States, the available frequency bands that may be used by 802.11ah are 902MHz to 928MHz. In South Korea, the available frequency bands are 917.5MHz to 923.5MHz. In Japan, the available frequency bands are 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz, depending on the country code.

[0046] 1D is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As mentioned above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. Additionally, the RAN 113 may be in communication with the CN 115.

[0047] The RAN 113 may include gNBs 180a, 180b, and 180c, although it will be understood that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, and 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In one embodiment, the gNBs 180a, 180b, and 180c may implement MIMO techniques. For example, the gNBs 180a, 180b may utilize beamforming to transmit and / or receive signals to the gNBs 180a, 180b, and 180c. Thus, for example, the gNB 180a may use multiple antennas to transmit and / or receive wireless signals to the WTRU 102a. In an embodiment, the gNBs 180a, 180b, and 180c may implement carrier aggregation techniques. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of the aforementioned component carriers may be on a non-licensed spectrum, while the remaining component carriers may be on a licensed spectrum. In an embodiment, the gNBs 180a, 180b, and 180c may implement Coordinated Multi-Point (CoMP) techniques. For example, the WTRU 102a may receive coordinated transmissions from the gNBs 180a and 180b (and / or 180c).

[0048] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for separate transmissions, separate cells, and / or separate portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of various or scalable lengths (e.g., including various numbers of OFDM symbols and / or various absolute time lengths).

[0049] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c without accessing another RAN (e.g., eNode-Bs 160a, 160b, 160c, etc.). In a standalone configuration, the WTRUs 102a, 102b, 102c may utilize one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with a gNB 180a, 180b, 180c while also communicating / connecting with another RAN, such as, for example, an eNode-B 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-Bs 160a, 160b, 160c may act as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput in serving the WTRUs 102a, 102b, 102c.

[0050] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data to User Plane Functions (UPFs) 184a, 184b, routing of control plane information to Access and Mobility Management Functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D , the gNBs 180a, 180b, 180c may communicate with each other via an Xn interface.

[0051] 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one SMF (Session Management Function) 183a, 183b, and possibly a DN (Data Network) 185a, 185b. While each of the above elements is depicted as part of the CN 115, it will be understood that any of the just-mentioned elements may be owned and / or operated by an entity other than the CN operator.

[0052] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling sessions for separate PDUs with separate requirements), selecting a particular SMF 183a, 183b, managing registration areas, terminating NAS signaling, mobility management, etc. Network slicing may be used by the AMF 182a, 182b to customize CN support for the WTRUs 102a, 102b, 102c based on the type of service being utilized for the WTRUs 102a, 102b, 102c. For example, separate network slices may be established for separate use cases, such as services dependent on ultra-reliable, low-latency (URLLC) access, services dependent on enhanced massive mobile broadband (eMBB) access, services related to machine-type communications (MTC) access, etc. The AMF 162 may provide control plane functionality for switching between the RAN 113 and other RANs (not shown) employing other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0053] The SMFs 183a, 183b may be connected to the AMFs 182a, 182b in the CN 115 via an N11 interface. Additionally, the SMFs 183a, 183b may be connected to the UPFs 184a, 184b in the CN 115 via an N4 interface. The SMFs 183a, 183b may select and control the UPFs 184a, 184b and configure the routing of traffic through the UPFs 184a, 184b. The SMFs 183a, 183b may perform other functions such as, for example, managing and assigning IP addresses for WTRUs, managing PDU sessions, controlling policy enforcement and QoS, providing downlink data notification, etc. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0054] The UPFs 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface and 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. The UPFs 184, 184b may perform other functions such as, for example, routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, etc.

[0055] The CN 115 may facilitate communication with other networks. For example, the CN 115 may include or communicate with an IP gateway (e.g., an IMS (IP Multimedia Subsystem) server) that acts as an interface between the CN 115 and the PSTN 108. In addition, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local DNs (data networks) 185a, 185b through an N3 interface to the UPFs 184a, 184b, and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0056] 1A-1D and the corresponding descriptions thereof, one or more or all of the functions described herein in connection with one or more of the WTRUs 102a-d, base stations 114a-b, eNode-Bs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-ab, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other device(s) described herein may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functionality.

[0057] The emulation device may be designed to implement one or more tests of other devices in a lab environment and / or in an operator's network environment. For example, one or more emulation devices may perform one or more, or all, functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communications network to test other devices in the communications network. One or more emulation devices may perform one or more, or all, functions while temporarily implemented / deployed as part of a wired and / or wireless communications network. The emulation device may be directly coupled to another device for testing purposes and / or may perform testing using over-the-air (OTA) wireless communications.

[0058] The one or more emulation devices may perform one or more functions, inclusive, while not being implemented / deployed as part of a wired and / or wireless communications network. For example, the emulation devices may be utilized in testing laboratories and / or testing scenarios in undeployed (e.g., testing) wired and / or wireless communications networks to implement testing of one or more components. The one or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may, for example, include one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0059] The following description is for illustrative purposes and is in no way intended to limit the applicability of the methods employed by one or more WTRUs, base stations, eNBs, other devices, etc. Embodiments may relate to alternative wireless technologies, topologies, and / or distinct technical principles, when applicable or desired. As used herein, the term network may refer to one or more gNBs that may be associated with one or more transmission reception points (TRPs) or other nodes of a radio access network. A network may include other elements, such as those illustrated in FIGS. 1A-1D.

[0060] Mobile communications technology is constantly evolving, and its fifth incarnation, 5G, is on the horizon. As with previous generations, new use cases have significantly contributed to the configuration requirements of new radio systems. New Radio (NR) is a new radio technology being developed for 5G. The access air interface of NR is more flexible compared to the air interface of legacy technologies. For example, NR may be able to support multiple RATs (Radio Access Technologies) in both licensed and unlicensed bands.

[0061] In embodiments, the design of a 5G system may correspond at least in part to an NR access technology that meets 5G requirements. Embodiments are in no way limited to NR, 5G, or any other technology standard, implementation, or technology.

[0062] The 5G air interface is expected to enable at least the following use cases: improved broadband performance (IBB), industrial control and communication (ICC), vehicular applications (V2X), and massive machine-type communication (mMTC). The use cases just mentioned can be translated into the following requirements for the 5G air interface: support for ultra-low transmission latency (LLC), support for ultra-reliable transmission (URC), and support for MTC operation, including narrowband operation.

[0063] Air interface latencies as short as 1 ms RTT (round trip time) may require support for TTIs in the range between 100 us and 250 us (or less). Support for ultra-low access latencies, e.g., the time from initial system access to transmission completion for the first user plane data unit, may be of interest but of lower priority. ICC and V2X may require e2e (end-to-end) latencies of less than 10 ms.

[0064] One design consideration for NR implementations includes higher transmission reliability than is possible with legacy LTE systems. For example, the goal could be close to 99.999% transmission success and service availability. Another consideration could be support for mobility for speeds ranging from 0 to 500 km / h. IC and V2X, at least, will be able to achieve 10e -6 It is possible that a packet loss rate of less than 100 Mbps may be required.

[0065] The air interface should efficiently support narrowband operation, e.g., using less than 200 KHz, extended battery life, e.g., reaching 15 years of autonomy, and minimal communication overhead for small and infrequent data transmissions, e.g., low data rates in the range of 1-100 kbps with access latencies of a few seconds to a few hours.

[0066] OFDM is used as the basic signal format for data transmission in both the LTE and IEEE (Institute of Electrical and Electronics Engineers) 802.11 standards. Essentially, OFDM effectively divides the spectrum into multiple parallel, orthogonal subbands, called subcarriers. Each subcarrier is shaped using a rectangular window in the time domain, which derives a sinc-shaped subcarrier in the frequency domain. Therefore, OFDMA requires perfect frequency synchronization and strict control of uplink timing alignment within the duration of the cyclic prefix to maintain orthogonality between signals and minimize inter-carrier interference. Furthermore, such strict synchronization may be less suitable in systems where WTRUs are simultaneously connected to multiple access points. Furthermore, additional power reduction is typically applied to uplink transmissions to ensure compliance with spectral emission requirements in adjacent bands. The need to ensure compliance is particularly relevant where there is aggregation of fragmented spectrum for WTRU uplink transmissions.

[0067] It is recognized that some of the shortcomings of CP-OFDM (conventional OFDM) may be offset by more stringent RF requirements for implementation, especially when operating using large amounts of contiguous spectrum that does not require aggregation. Furthermore, CP-based OFDM transmission methods may evolve into downlink physical layers for 5G similar to those of legacy systems, with modifications, for example, primarily to the density and location of pilot signals. Therefore, while 5gFLEX (5G Flexible Radio Access Technology) designs may also consider other waveform candidates, conventional OFDM remains a potential candidate for 5G systems, at least for the downlink.

[0068] The 5gFLEX radio access design may be characterized by a high degree of spectrum flexibility, allowing for the development of distinct frequency bands with distinct characteristics, including distinct and / or variable sized available spectrum, including distinct duplex arrangements, contiguous and non-contiguous spectrum allocations, in the same or distinct bands. Furthermore, 5gFLEX may support variable timing aspects, including support for multiple TTI lengths, and may support asynchronous transmission.

[0069] Both TDD (Time Division Duplex) and FDD (Frequency Division Duplex) duplexing schemes may be supported. For FDD operation, supplemental downlink operation may be supported using spectrum aggregation. FDD operation may support both full-duplex FDD and half-duplex FDD operation. For TDD operation, DL / UL allocation may be dynamic, e.g., it may not be based on a fixed DL / UL frame structure; rather, the length of the DL or UL transmission interval may be set for each transmission opportunity.

[0070] 2 is an example 200 of a WTRU 202 in communication with a gNB 204. Communication with the gNB 204 may involve communication using a downlink carrier 206, a primary uplink carrier 208, and a supplementary uplink (SUL) carrier 210. The SUL carrier may be configured to operate supplementally or in addition to the primary uplink carrier 208. The serving cell or gNB 204 may be configured with one or more additional uplink carriers, e.g., one or more SUL carriers. In one embodiment, the SUL 210 may be used to extend the coverage of a WTRU operating at a higher frequency, such that the WTRU may transmit on the SUL when configured with a lower frequency band, e.g., with the primary UL carrier 208. This may be useful when the WTRU is moving toward the edge of coverage of the cell's primary uplink carrier. Additionally, lower frequency resources may be more reliable, as they may be more likely to penetrate objects such as walls. Another potential use of the SUL may be for the provision of certain services, such as services offering increased demands for high throughput and / or reliability. In particular, what has just been stated may be possible if the WTRU is configured to perform transmissions on multiple uplinks that are transmitted simultaneously or near simultaneously to the relevant cells, e.g., in a TDM stream. As used herein, the primary uplink carrier of the WTRU may be referred to as the regular uplink (RUL) carrier. Similarly, the terms RUL carrier and normal uplink (NUL) carrier may be used interchangeably.

[0071] In one embodiment, a SUL may be created when a cell has a DL carrier associated with two separate UL carriers. The uplink carriers may consist of or be configured with a primary UL carrier located in a higher frequency band when a DL carrier is also deployed, and a SUL carrier that may be in a lower frequency band.

[0072] FIG. 3 is an example 300 of multiple bandwidth portions 304-312 configured by a frequency band or bandwidth 302. Each bandwidth portion 304-312 may consist of a subset of contiguous resource blocks (RBs) on a carrier. In one embodiment, a WTRU may be limited to four bandwidth portions configured simultaneously. In other embodiments, a WTRU may be limited to more or fewer bandwidth portions. In the example shown in FIG. 3, the primary uplink carrier 316 is located in bandwidth portion 4 312, at the top of the frequency spectrum configured by the WTRU. The primary downlink 318 is configured in bandwidth portion 3 310. The lowest configured bandwidth portion is bandwidth portion 2 308, in which the SUL 314 is configured. Bandwidth portion 0 304 and bandwidth portion 1 306 do not have any uplink or downlink carriers configured for the WTRU.

[0073] The SUL may be configured for any type of cell, including, but not limited to, a primary cell (PCell), a secondary PCell (SPCell) for dual connectivity, as well as a secondary cell (SCell). The SUL may be configured for a standalone system or for a cell belonging to a multi-RAT dual connectivity system.

[0074] A WTRU may perform initial access to a cell using either the RUL or SUL carrier. The SUL configuration may be provided via a broadcast transmission in the smallest system information (SI) transmission belonging to the cell. For example, the WTRU may select the SUL for initial access if it determines that the DL quality of the serving cell is below a threshold. The threshold may be pre-configured or determined by the WTRU at some point in time. In one embodiment, the location or bandwidth may be provided via broadcast along with the subcarrier spacing and cyclic prefix. The SUL configuration may include a single SUL configuration or multiple SUL configurations for using uplink bandwidth portions of multiple SULs. In one embodiment, the configuration of only a single RUL or only a single SUL may be broadcast in the SI.

[0075] Separate modes of operation may be possible for a WTRU using the SUL in the connected mode of radio resource control (RRC). In a first mode, the RRC may configure the WTRU with multiple UL carriers, one of which may be an RUL carrier with the typical uplink configuration of the relevant cell, and another of which may minimally include a sounding reference signal (SRS) configuration, such as an SUL carrier. In the above modes of operation, the WTRU may use the RUL carrier for all control and data transmissions in the uplink. In addition, the WTRU may transmit the SRS using the resources of the SUL carrier. RRC reconfiguration may activate and / or switch the active uplink carrier applicable to a cell for some or all transmissions, providing extended, typical, and / or complete uplink configurations for different carriers. In some embodiments, the SUL carrier may be used for transmission of other control information.

[0076] In a second mode, RRC signaling may provide an extended, typical, and / or complete uplink configuration to a WTRU with multiple uplink carrier configurations. In this case, the WTRU may have sufficient configuration to perform some or all types of uplink transmissions, e.g., physical uplink control channel (PUCCH), physical uplink shared channel (PUSCH), and / or physical random access channel (PRACH), over resources of one or more involved carriers. The WTRU may then receive control signaling, e.g., via MAC CE (Control Element) or downlink control information (DCI) signals, that activates and / or initiates switching between UL configurations.

[0077] 4 illustrates an example MAC CE command 400. In one embodiment, the MAC CE command 400 may include a header 402 indicating the addition of an SUL carrier. A data field 404 may follow the header 402 and indicate uplink frequency information for the added SUL carrier. This may allow the WTRU to either activate a known SUL carrier on that frequency or add an SUL carrier on a given frequency to the configuration for later activation.

[0078] In a third mode, the RRC protocol may provide the WTRU with multiple uplink configurations, and two or more uplink configurations may be active either simultaneously or in a time-division stream. In one embodiment, the above modes of operation include restrictions such that the WTRU may not be required to perform some or all types of uplink transmissions simultaneously, e.g., the WTRU may not be required to transmit PUSCH to a cell on multiple uplink carriers simultaneously. In an embodiment, the above restrictions may be configured for the WTRU, particularly if the WTRU's capabilities indicate, for example, that the above simultaneous transmissions are not supported in one or more configured frequency bands. A WTRU of the type just described may be a half-duplex WTRU operating with a single oscillator. Alternatively, or in combination, the WTRU may be characterized as an MTC-type WTRU.

[0079] Devices that may not be able to support one or more frequency bands with wide channel bandwidth include low-complexity devices, such as Internet of Things (IOT) devices, which may be less complex than full-featured devices and may be limited to operating in one or more narrow bands.

[0080] A WTRU may be configured with one or more BWPs (Bandwidth Portions) for a given cell and / or carrier. The BWP may be characterized by at least one of the following: subcarrier spacing, cyclic prefix, or number of consecutive physical resource blocks (PRBs). The aforementioned characteristics may be aspects of the WTRU's configuration and may be specified depending on the WTRU's capabilities. Additionally, the BWP may be further characterized by a frequency location, e.g., a center frequency. In an embodiment, the BWP may be characterized from another frequency location, i.e., a frequency offset.

[0081] A WTRU may be configured with an initial BWP, e.g., from receiving system information. For example, a WTRU may be configured to access the system using an initial BWP for a given cell and / or carrier. In one embodiment, the access may be an initial access, e.g., when the WTRU is in idle mode and / or the WTRU determines that it should establish an RRC connection to the system. For example, the configuration of the initial BWP may include configuration for random access.

[0082] For example, a WTRU in CONNECTED mode may be further configured with a default BWP. The default BWP may be similar to or different from the initial BWP. The WTRU may revert to the default BWP upon expiration of a timer, e.g., after a period of scheduled inactivity. The WTRU may be configured with additional BWPs. For example, the WTRU may be configured with a BWP for a particular type of data transfer, e.g., for transmission of URLLC.

[0083] Cell-based wireless systems typically operate with a downlink carrier frequency and, optionally, an uplink carrier frequency for a given cell. The introduction of an SUL carrier extends the modeling of cells belonging to existing systems by supporting more than one uplink carrier. For NR, a WTRU may therefore be configured to operate with zero, one, or two uplink carriers, e.g., with a RUL and SUL with a single downlink carrier. Additional WTRU behavior may be useful in wireless systems that support the above additional configurations. For example, a WTRU may be configured with two or more uplink carriers in separate frequency bands. If this is the case, procedures traditionally performed based on obtaining path losses for paired downlink transmissions on the same carrier may be adversely affected. This is because two or more uplink carriers on separate frequency bands do not necessarily have mirrored channel conditions.

[0084] For example, the selection of applicable uplink carriers when performing a Layer 2 procedure may depend on several factors that may differ from prior systems. This may include conditions, criteria, and triggering events for determining which of multiple configured uplink carriers are applicable to a particular procedure. Additionally, one or more transitions midway through a procedure may also be effected, for example, during any ongoing procedure.

[0085] Additional system improvements may be possible with support of SUL, such as, for example, using resources of two or more uplink carriers to perform data duplication and / or simultaneous message transmission, etc. Furthermore, the above improvements may be possible when a WTRU is configured to use two or more available UL carriers to transmit information to an access point, base station, gNB, or other transmit-receive point, for example, when propagation conditions of one carrier deteriorate and / or when high reliability is required.

[0086] A WTRU may be configured with one or more SUL carriers. For example, a WTRU may be configured with multiple SULs for a given cell. Hereinafter, embodiments consider the case of a single SUL configured by the WTRU. Furthermore, methods may also be applicable to configurations in which a WTRU is configured with multiple SULs. In an embodiment, the SULs may be configured individually or in combination with each other. Accordingly, embodiments may be described using the terms SUL or SUL carrier. The previously described embodiments may be applicable to a band of SULs, i.e., one or more SUL bands. As noted above, some methods may be applied to one uplink carrier or to a subset of uplink carriers. For example, the WTRU may initially select a first subset of applicable uplink carriers based on downlink measurements reaching a certain threshold. The WTRU may then make further determinations of applicable uplink carriers, for example, based on receiving downlink control scheduling. In one example, the uplink carrier may be represented as a configured uplink BWP. For example, several methods for the WTRU to make applicable UL decisions may be based on the method used to determine the BWP and may also be performed in combination with other methods. In one embodiment, the BWP decision may be a decision that pertains only to the uplink.

[0087] The WTRU may employ one or more different methods for RUL / SUL selection. For example, methods may be employed to use static, semi-static, or dynamic determination of applicable uplink carriers. Examples include RUL and SUL selection and / or activation. For example, static methods, typically by configuration or by configuration from receipt of system information and / or by pre-configuration, semi-static methods, typically by L3 signaling and / or RRC control, or dynamic methods, typically by L1 / L2 signaling and / or L1 / MAC control, may be employed. In some examples, the configuration may be pre-configured or network-controlled. If network-controlled, semi-static or dynamic signaling may be used. Additionally or alternatively, the selection may be WTRU-controlled. Using pre-configured signaling, the WTRU may be configured with both a RUL and a SUL simultaneously. In one embodiment, the SUL may be used for transmission of the SRS. Furthermore, a threshold may be defined or pre-configured to determine the selection of one of the RUL and the SUL. Network-controlled signaling, semi-static configuration, or dynamic signaling approaches may be used to provide the selection. Using semi-static configuration, the WTRU may be configured with the RUL and only one threshold. Later, the WTRU may be configured with the SUL based on a specific event. In one embodiment, the SRS may be configured on the SUL. The configuration may be provided, for example, by the RRC.

[0088] Using dynamic signaling techniques, the WTRU may receive downlink control information, e.g., via a DCI indication or MAC CE, indicating that the WTRU should use the SUL or RUL. For example, reconfiguration of a cell with an SUL may be conveyed via DCI, e.g., for cross-carrier scheduling using the carrier ID of the SUL carrier, or for controlling the BWP of the associated SUL, e.g.

[0089] Furthermore, a combination of semi-static and dynamic configuration / signaling may also be used. For example, a DCI with a specific HARQ process ID may be used to convey information to the WTRU to use one or both of the SUL or RUL. In the above example, the WTRU is first configured with a set of HARQ processes for the RUL and the SUL that are different, and then the WTRU makes a decision on which UL to use based on the process ID indicated by or included in the DCI, which may be configured or dynamically assigned.

[0090] In a WTRU-initiated approach, the WTRU may determine that a threshold has been reached and may initiate a procedure to perform a switch or selection between the SUL and the RUL, or both. The above procedures may include a method for the network to determine that a change in the applicable uplink carrier may have occurred, for example, by the WTRU initiating transmission of SRS over the applicable carrier, and / or from a random access procedure, and / or from transmission of uplink control information. The network may then take action to indicate the switch, for example, via MAC CE, DCI, RRC, etc. In one embodiment, the network may provide UL-SCH resources on the SUL.

[0091] Some embodiments include combinations of the foregoing. Additionally, there may be dynamic reasons for switching or for UL carrier selection that may be determined based on at least one of the following criteria: system-related timing, type of transmission, SCS applicable to the transmission, configuration of LCH (logical channel), service, payload including amount of data available for transmission and / or data size, indication of UL grant or DL ​​allocation, RV of transmission, speed and QOS of the WTRU.

[0092] The system-related timing may include, for example, a number of symbols, minislots, slots, subframes, and / or subframes that may be associated with a particular UL carrier. For example, the type of transmission may be or may include uplink control information, RRC, data, signaling, and / or uplink channels, e.g., PUCCH, PUSCH, SRS, etc., or other uplink channel transmissions. The WTRU may perform transmissions of uplink control information, e.g., HARQ feedback, channel quality indication, etc., using a first carrier, e.g., an RUL carrier, while performing data transmissions over resources of a second carrier, e.g., an SUL. This separation of control information and data transmissions may occur when the WTRU determines that a certain threshold is met. The threshold may include consideration of the subcarrier spacing (SCS) or LCH configuration.

[0093] The WTRU may take into account the SCS applicable to a given transmission. For example, the WTRU may perform a first transmission using resources of a first uplink carrier configured with a first SCS and may perform a second transmission using resources of a second uplink carrier configured with a second SCS as a function of configuration aspects, e.g., the association between the bearer type, e.g., signaling radio bearer (SRB) or data radio bearer (DRB), and the applicable SCS.

[0094] The WTRU may consider the configuration of the LCH for a given transmission. For example, the WTRU may be configured with an association between one or more applicable uplink carrier(s) and an LCH or group thereof, e.g., an LCG for transmission of data from the relevant LCH(s). The WTRU may determine the applicable uplink carrier when it determines that it has new data available for transmission as a function of the LCH associated with the data.

[0095] The service type, e.g., URLLC, eMBB, mMTC, may be considered while determining whether a transmission occurs via the RUL or SUL. In addition, the payload, including the amount of data available for transmission and / or the data size, may be considered in the determination. For example, the WTRU may be configured to determine the applicable uplink carrier as a function of the size of the data to be transmitted. The size may correspond to a transport block, MAC PDU, RLC PDU, or PDCP PDU for a given transmission. The size may correspond to the total amount of data available for transmission for one, a subset, or all of the LCH(s). For example, the WTRU may determine that it should use resources of a first uplink carrier, e.g., SUL, if it determines that the amount of data is below a threshold. Otherwise, the WTRU may use resources of a second uplink carrier. In one embodiment, the above may be in combination with one or more other criteria. If the WTRU is configured with an SUL, the WTRU may determine that it should use resources of a first uplink carrier, e.g., RUL, if it determines that the amount of data exceeds a threshold and if the estimated path loss is less than the threshold and / or less than the available power minus a value associated with the relevant data size. Otherwise, the WTRU may use resources of a second uplink carrier, e.g., SUL.

[0096] The WTRU may take into account an indication received in the UL grant or DL ​​assignment. For example, the WTRU may receive downlink control signaling indicating an uplink carrier applicable for transmitting HARQ feedback for a downlink transmission. For example, the WTRU may receive downlink control signaling indicating an uplink carrier applicable for transmitting a transport block in an uplink transmission. In one embodiment, the indication may be a configuration aspect, e.g., for a configured grant and / or for semi-persistent scheduling.

[0097] The WTRU may consider the RV of the transmission while determining the applicable UL carrier. For example, the WTRU may determine the applicable UL carrier from the sequence of (re)transmissions for the HARQ process. For example, an HARQ retransmission may use a different UL carrier than the previous (re)transmission as a correlation of the applicable redundancy version. The speed and QoS of the WTRU, e.g., latency requirements for the transmitted data, are additional criteria.

[0098] Figure 5A shows a 3-bit RV counter 500. In Figure 5A, the least significant bit 504 is configured to count from 0 to 3 decimal, or 00 to 11 binary. In one embodiment, the WTRU may start with a redundancy version of 0. Each time a transmission goes into an error state, the WTRU may increment the RV by 1. If a rollover occurs, the left-most bit 502 will change from 0 to 1. This may indicate a switch point for SUL usage.

[0099] FIG. 5B is a state diagram 520 illustrating the 3-bit RV counter of FIG. 5A. In one embodiment, the WTRU may change states if a random access or other transmission fails. In each state, the redundancy version may be different from the previous state. For example, the first state 522 represents a 2-bit RV 504 at 0. For a failed transmission, the RV is incremented as the WTRU enters the second state 524. The WTRU may then enter a third state 526, followed by a fourth state 528 if necessary. Upon entering the fourth state 528, the WTRU increments the RV, which may toggle the switch point 530 for the SUL. If the switch point just mentioned occurs, the WTRU may enter the first state 532 corresponding to the SUL and continue to increment the RV as necessary. The WTRU may enter the second state 534, the third state 536, and the fourth state 538. Each of the just mentioned states represents a distinct RV in which the WTRU may make an alternative or redundant transmission compared to the previous transmission in the previous state. The WTRU may cycle back to the RUL after a timer expires or another event occurs or occurs.

[0100] The WTRU may perform one or more random access procedures over the SUL. The WTRU may initiate an RA procedure, for example, during initial access or at handover, using resources associated with an uplink carrier configured as the default uplink carrier. If the WTRU receives an indication to switch to the SUL or if a condition for switching to the SUL is triggered, the WTRU may perform an RA procedure for an uplink carrier other than the default carrier, for example, for the SUL.

[0101] In one embodiment, in addition to the switching methods described above, during the initial access transition from RRC_IDLE to RRC_CONNECTED, the following events may also be taken into consideration: The WTRU may receive the configuration of the SUL in the delivery of the remaining minimum system information (RMSI). If the received RSRP is below a threshold, the WTRU may use the SUL for the RACH. Otherwise, the WTRU may perform a RACH procedure over the regular uplink. In addition to the switching methods just described, the following trigger conditions for generating an RA procedure for the SUL are listed below:

[0102] The WTRU may have a maximum number of retransmissions for RUL, preambleTransMax_RUL, which may be reached before the WTRU switches to SUL. Another value of preambleTransMax_SUL may be set for SUL, and the WTRU may attempt its RACH according to the same rules.

[0103] The WTRU may be configured with a single number of retransmissions (preambleTransMax) applicable to one or both of the RUL and SUL. The WTRU may alternate between RACH attempts on the RUL and RACH attempts on the SUL in each power ramping step. Alternatively, the WTRU may increment the power each time before switching for a single RUL or SUL. The WTRU may increment the preamble transmission counter once for attempts on both the RUL and SUL, or based on individual attempts independent of the applicable uplink carrier. The WTRU may be configured with separate parameters for each uplink carrier.

[0104] When a WTRU performs RA on the RUL, the WTRU may increase its transmit power on each attempt. The WTRU may perform beam selection for each attempt, e.g., the WTRU may try different beams until the WTRU determines that the transmission is successful. In one embodiment, P c_max If one or more attempts using the RUL are reached, the WTRU may switch to the SUL. The WTRU may reinitialize the transmit power after a change of uplink carrier, e.g., SUL. The WTRU follows the same rule and increases the power by the same or a different pc_max configured to the value associated with the SUL.

[0105] 6 is a flowchart 600 of a WTRU initiating an RA procedure. If the WTRU initiates a RACH procedure for the RUL 602, the WTRU may receive an indication in msg2 to switch to another uplink carrier, e.g., the SUL 604, and the UL grant for msg3 may be applicable to resources associated with the other uplink carrier, e.g., the associated SUL band. In one example, the WTRU may use the SUL for handover when the device is in RRC_CONNECTED mode. The WTRU may determine 606 whether the RA will be performed as a contention-based procedure or a contention-free procedure.

[0106] During contention-free random access 606, the WTRU may receive 608 the configuration of the SUL or RUL with the associated dedicated or common RACH resource in the HO command. If the WTRU is configured with dedicated RACH resources for both the SUL and RUL, the selection of the PRACH resource may depend on at least one of the following: the received RSRP of the DL beam paired to the RUL, such that the WTRU transmits on the PRACH associated with the SUL if the RSRP is below a configured threshold; the timing of the PRACH resource; and a request to beam-sweep the RACH transmission. Depending on whether the WTRU needs to beam-sweep the PRACH transmission onto either the RUL or the SUL, the WTRU may select the appropriate carrier 610. For example, if the UL transmit beam may not be determined from the DL receive beam, the WTRU may be required to beam-sweep the PRACH transmission. In another example, the UL BPL (Beam Pair Link) may have an expiration timer, and if the UL BPL is still valid, the WTRU may not need to beam sweep the PRACH transmission.

[0107] If a WTRU is configured with dedicated RACH resources for the SUL and common RACH resources for the RUL, the WTRU may prioritize the dedicated RACH resources for the SUL and may return to the RUL only if random access on the SUL fails. Alternatively, if a WTRU is configured with dedicated RACH resources for the RUL and common RACH resources for the SUL, the WTRU may prioritize the RACH resources dedicated to the RUL and may return to the SUL only if random access on the RUL fails.

[0108] For contention-based random access 612, the WTRU may select a common RACH resource associated with either the RUL or SUL based on at least one of the target cell's RSRP, the PHR for each UL carrier, the timing of the PRACH resource, and / or the index of the DL beam or SSB (synchronization signal block) used by the WTRU 614. The WTRU may transmit a preamble over both the RUL and SUL resources 616. The WTRU may use a single RA-RNTI for both resources or calculate two separate RA-RNTIs for the RUL and SUL 618. For example, the WTRU may transmit a preamble over both the RUL and SUL in a manner that allows the network to know that the two preambles originate from the same WTRU. For example, the WTRU may add a short signature sequence to each preamble transmission. This may enable the WTRU to determine the appropriate UL carrier on which to continue for the RA procedure. The WTRU may monitor for RAR using two different RA-RNTIs corresponding to both transmissions on the uplink.

[0109] In another method, for transmitting preambles on both the RUL and SUL, the WTRU may expect, monitor, and receive an RAR corresponding to each preamble transmission. The RAR may provide information to the WTRU to enable it to select an appropriate grant, for example, an UL carrier to use for transmitting msg3. In an example, each RAR may include a quality metric that may indicate to the WTRU whether to continue the RA on the RUL or to use the SUL. The WTRU may transmit msg3 over the UL resources indicated in the RAR. The WTRU may transmit msg3 on the UL associated with the first RAR received. Conditions for generating an RA procedure for the SUL for an RA in connected mode triggered by an SR procedure or due to timing offset for any UL may include the following: The WTRU may determine whether the QoS or priority of the LCH that triggered the SR in connected mode is within a configured set. The above may be conditioned on the UL coverage and the periodicity of the PRACH resources for the UL and SUL in the time domain. The WTRU may decide whether the RA-triggered SR configuration is used to differentiate requests for resources for the SUL. This decision may be used with the WTRU autonomously switching between the UL and SUL for PUSCH transmission. If the RA-triggered SR configuration includes PUCCH resources for the SUL, the WTRU may switch to the SUL for transmission of msg3. The WTRU may consider other circumstances, such as the buffer status or power headroom (PHR) for each UL carrier or the timing of the SR resources, while deciding whether to switch to the UL carrier.

[0110] In general, if an event is triggered to generate an RA on the SUL and the WTRU has already initiated an RA procedure for the RUL, the WTRU may terminate the RUL RA procedure even if it has not reached preambleTransMax, the WTRU may wait for the RUL RA procedure to complete, and the WTRU may initiate a parallel RA procedure for the SUL if the WTRU has the capability, or continue the procedure with the SUL if the WTRU has the capability.

[0111] The WTRU may calculate the RA-RNTI when transmitting two separate preambles. In one embodiment, the WTRU may calculate a single RA-RNTI based on the resource selection for the preamble on one of the carriers, e.g., on one of the SUL or RUL. In one embodiment, the just-described selection is configurable. The just-described method may be applicable when the PRACH resource selection for the RUL and SUL are identical or have a relationship that may be detectable by the base station or network. In another embodiment, the WTRU may calculate two independent RA-RNTIs based on the PRACH resources selected by the WTRU, assuming that the resources are selected independently for each carrier. In another embodiment where the same preamble resource selection can be applied to both carriers, the WTRU may calculate two RA-RNTIs, for example, by applying a carrier offset to the calculation. The WTRU may decide on which UL to transmit based on the RA-RNTI it used to decode msg2.

[0112] For resource selection for random access of a WTRU configured with a SUL, the resources may be divided into two groups, Group A and Group B, e.g., in LTE for an SpCell. Alternatively, or in combination, the just-mentioned grouping may be kept only for the RUL. If such grouping exists, the MAC entity may select the group A if the potential message size, e.g., plus the MAC header and MAC control elements as needed for the UL data available for transmission, is larger than messageSizeGroupA and the path loss is less than P (of the serving cell performing the RA procedure). CMAX,c If -preambleInitialReceivedTargetPower-delta is less than PreambleMsg3-messagePowerOffsetGroupB, then one of the PRACH resources in Group B may be selected randomly.

[0113] The path loss estimate may be obtained based on the estimated path loss of the DL carrier from which the WTRU receives the RMSI. Otherwise, the MAC entity may select a preamble from the RA preambles of group A.

[0114] If the WTRU is unable to estimate the path loss based on the DL carrier or the network explicitly indicates to the WTRU that it does not consider path loss in selecting the group, the MAC entity randomly selects one of the PRACH resources based solely on the size of msg3.

[0115] FIG. 7 is a flowchart 700 illustrating an example method for determining whether to switch to the SUL for an RA. First, the WTRU may select 702 an RUL PRACH resource in the active BWP of the RUL carrier. The WTRU may transmit on the PRACH resource and determine whether the transmission was successful. If not, the WTRU may check a running counter for the number of retries. If the counter is less than the maximum number of retransmissions 704 and the maximum transmit power Pcmax has not been reached 706, the WTRU may select 702 another RUL PRACH resource in the active BWP. Otherwise, if Pcmax is met, the WTRU may select 708 an SUL PRACH resource in the active BWP. The WTRU may calculate 710 the RA-RNTI based on the PRACH resource selected in the RUL selection 702 and apply the offset of the SUL carrier to it. The UE may transmit a PRACH on the SUL and monitor 712 msg2 based on the resulting RA-RNTI. If the RA procedure is successful for the SUL 714, the procedure may end and the WTRU may use the SUL accordingly. If the procedure is not successful, the WTRU may determine 716 whether the maximum number of retransmissions has been reached. If the maximum number of transmissions has not been met, the WTRU may retransmit on the SUL. If the maximum number of transmissions has been met, the UE may change the active BWP 718 and revert to the default BWP. Then, again, the WTRU may select 718 an SUL PRACH resource in the new active BWP.

[0116] The random access procedure for the SUL carrier may be performed in a beamformed system. The WTRU described so far may be configured with an SUL in a lower NR band, e.g., cmWave (centimeter wave), which may have better propagation characteristics than the higher regular band in which the WTRU is configured to perform its UL transmission. The same trigger conditions as for the SUL in a sub-6 GHz band (e.g., LTE band) may apply. However, the random access procedure in the case of a WTRU in connected mode is affected in the just-described scenario.

[0117] The WTRUs may be configured with RACH resources associated with CSI-RS and NR-SS, respectively. The WTRUs may measure beams associated with the reference signals mentioned above. If the measured quality is above a certain threshold, the WTRUs may first attempt on dedicated RACH resources (whether associated with SSB or CSI-RS resources) and then, if necessary, revert to common RACH resources associated with SSB.

[0118] Being able to measure the DL reference signal associated with each one of the beams may enable the WTRU to determine the beam compatibility before performing the RA procedure for those beams. However, in the case of the SUL in a beamformed system, the WTRU is not able to determine the compatibility of the beam associated with the SUL.

[0119] In one or more embodiments, a beamformed SUL RACH procedure may be performed without DL or UL channel information. If co-location or partial beam correspondence is assumed to exist, a cmW RACH procedure using a wider beam could be based on a mmW DL SSB reference. The reference may take into account path loss compensation between cmW and mmW. In one embodiment, beam sweeping may be employed. By sweeping the beam, multiple msg1 transmissions may be performed by the SUL beam. In one embodiment, SRS transmissions may be beamformed. In one embodiment, the WTRU may always use SSB when the WTRU performs a RACH procedure for SSB.

[0120] An SR configuration may be made in the context of SUL or UL. The WTRU may use one or more SR configurations to indicate the type of UL transmission resource. The UL resources may be distinguished by whether the UL-SCH resources are in the RUL or USL. The WTRU may use the SR configuration with the WTRU autonomously switching between the RUL and SUL for PUSCH transmission. The indication may be made explicitly by selecting an SR configuration made available by the gNB to indicate a request for UL-SCH resources on the SUL compared to the RUL. In the above modeling, the SR configurations for RUL and SUL are invoked as separate SR procedures, and each SR configuration may have an SR counter, a maximum number of SR attempts, and an SR prohibit timer.

[0121] In an alternative modeling, a single SR configuration could include PUCCH resources on both the RUL and SUL. In the above case, the SR configuration may not be explicitly used to distinguish the UL for which UL-SCH resources are needed. Instead, the selected PUCCH resources in the configuration are used as an implicit indication of which UL is desired. The WTRU, in one embodiment, could transmit SRs simultaneously on both the RUL and SUL. This may allow for higher reliability and may also allow the network to load balance between the RUL and SUL.

[0122] Furthermore, the RRC may configure each logical channel with the appropriate SR configuration and corresponding PUCCH resources depending on whether the LCH is enabled to transmit SRs on the RUL, SUL, or both.

[0123] Furthermore, several criteria may be used to determine which SR configuration or which PUCCH resource within the SR configuration should be used for a given LCH. For example, the above criteria may depend on the UL and / or DL ​​coverage level. In one example, a reference signal received power (RSRP) measurement combined with a configured or predefined threshold may be used to further determine which SR configuration and / or PUCCH resource to use. In another example, the WTRU's HARQ operation point may be used to further determine which SR configuration and / or PUCCH resource to use. For example, reaching a certain number of HARQ retransmissions on the RUL may result in the MAC entity triggering SR on a given SR configuration or a certain PUCCH resource. Similarly, a drop in the pathloss estimate or RSRP may result in the MAC entity triggering SR with a given SR configuration or a certain PUCCH resource.

[0124] If the gNB configures separate SR configurations to distinguish whether uplink shared channel (UL-SCH) resources are in the SUL or RUL, the LCH may be mapped to both configurations. If the SR counter of either configuration reaches its SR-transMax, the MAC entity may notify RRC to release PUCCH resources and may initiate random access immediately. Alternatively, the MAC entity may move to the other uplink SR configuration. If SR-transMax is reached for both SR configurations, the WTRU may notify RRC to release the associated PUCCH resources and initiate random access.

[0125] If the gNB configures a single SR configuration with PUCCH resources for both SUL and RUL, the MAC entity may maintain a single SR counter and may invoke a single SR procedure for the configuration. When the counter reaches Sr-transMax, the WTRU notifies the RRC to release any associated PUCCH resources and initiates random access. When random access is initiated as part of the SR procedure, the choice between SUL and RUL for RA may be prioritized.

[0126] A scheduling request (SR) failure may occur and may be handled appropriately by the WTRU. In one embodiment, the WTRU may be configured with one or more dedicated resource(s) for SR. For example, the resource(s) may be for transmitting SRs on the PUCCH. For example, the WTRU may be configured with one or more dedicated resources for SR (D-SR) for an uplink carrier. The WTRU may initiate an SR procedure using one or more D-SRs for the uplink carrier. The WTRU may determine that the maximum number of D-SR transmissions for the uplink carrier has been reached. The WTRU may be configured with D-SR for the RUL and / or for the SUL.

[0127] In the event of a D-SR failure for the RUL, SR may be triggered by the SUL or SUL activation. In one method, the WTRU may activate the SUL and / or initiate SR of SUL resources when it determines that the maximum number of D-SR transmissions for the RUL has been reached. The WTRU may perform SR using D-SR for the SUL if configured, or using a random access procedure if not.

[0128] A failure of D-SR for the UL carrier may trigger a reconfiguration of the WTRU to the cell's initial BWP. This may apply to any cell, with or without an SUL. In one method, the WTRU may determine that D-SR for an uplink carrier has failed when the WTRU determines that it has reached the maximum number of D-SR transmissions for the uplink carrier. The WTRU may then revert to the initial BWP for the first cell. The first cell may be the cell associated with the D-SR resources. Alternatively, the first cell may be the WTRU's primary cell, e.g., the WTRU may be configured with a PCell. Alternatively, the first cell may be the WTRU's primary cell such that it falls into a group of cells associated with the D-SR resources. In one embodiment, the WTRU may reconfigure the DL BWP to the initial BWP belonging to the first cell. In one embodiment, the WTRU may reconfigure the UL BWP to the initial BWP for the first cell, and then the WTRU may initiate an RA procedure using RA resources applicable to the initial BWP for the first cell.

[0129] A D-SR failure for the RUL may trigger a reconfiguration for the initial BWP for the cell and the RACH on the RUL. In one example where the WTRU is configured to perform RA using the initial BWP of the cell when it determines that a D-SR failure has occurred on the RUL, the uplink carrier for the first cell may be the RUL.

[0130] A D-SR failure for the SUL may trigger a reconfiguration for the initial BWP for the cell and the RACH on the SUL. In one example, when the WTRU determines that a D-SR failure occurred on the SUL, it is configured to perform random access using the initial BWP of the cell, and the uplink carrier for the first cell may be the SUL.

[0131] A contention-based random access procedure (CBRA) performed for the initial BWP may follow the SR failure. In one example, the WTRU may initiate a CBRA when initiating an RA procedure using the initial BWP, e.g., as determined in response to any of the aforementioned events. In one embodiment, this may be initiated only when the WTRU determines that the D-SR was not successful.

[0132] A RACH using a PRACH resource associated with a particular type of SS (synchronization signal) may follow an SR failure. In one example, the WTRU may initiate a random access procedure, e.g., CBRA, using a PRACH resource and / or configuration associated with a particular reference signal. The reference signal may be a cell-common reference signal, e.g., NR-SS. The reference signal may be a dedicated reference signal, e.g., CSI-RS or NR-SS. The WTRU may select the resource based on the reference signal and / or its type when it initiates the random access procedure using an initial BWP, e.g., as determined in response to any of the aforementioned events. In one embodiment, the D-SR procedure is initiated only when the WTRU determines that the D-SR procedure was not successful.

[0133] A RACH procedure for an initial BWP of the PCell may follow an SR failure. In one example, the WTRU may initiate a random access procedure for a PCell that it has configured when the WTRU initiates a random access procedure using an initial BWP, for example, as determined in response to any of the aforementioned events. In one embodiment, the RACH procedure is initiated only when the WTRU determines that the D-SR procedure was not successful.

[0134] For any of the above scenarios, the use of a default BWP may be used if configured. In one example, the WTRU may initiate a random access procedure for the default BWP if configured by the WTRU for the relevant cell. This initiation may occur when the WTRU initiates an RA procedure using an initial BWP, for example, as determined in response to any of the above events. In one embodiment, it is initiated only when the WTRU determines that the D-SR procedure was not successful.

[0135] Any of the above scenarios may apply to the general case of SR using either RACH, D-SR, or a maximum number of HARQ transmissions for grantless resources. In one example, the WTRU may perform any of the above procedures upon a determination that an attempt to acquire and / or use resources of a given cell and / or carrier was unsuccessful. In one embodiment, the determination may be made following the maximum number of transmissions and / or after a certain amount of time has elapsed since the start of a procedure, e.g., an SR procedure, a HARQ process, or a RACH procedure. The amount of time that has elapsed may be measured using a timer. When the timer expires, the WTRU is configured to act accordingly.

[0136] In one example, the WTRU may perform any of the above procedures based on determining that the maximum number of HARQ transmissions has been reached for a transport block using the configured uplink resources. For example, the configured uplink resources may be semi-persistent uplink grants, such as semi-persistent scheduling (SPS) grants. For example, the configured uplink resources may be for grant-less transmissions. For example, the configured uplink resources may be for transmissions with receipt of specific types of grants and / or dynamic control information for the resources.

[0137] In an embodiment, the WTRU may determine that it is experiencing a radio link failure when it determines that the RA procedure was not successful, e.g., using the resources of the cell associated with the initial BWP, following any of the above recognitions and / or combinations. Any of the above methods may be used alone or in combination.

[0138] In one scenario, a D-SR failure may occur first for the RUL, and then a D-SR failure may occur for the SUL. In response, the WTRU may perform a RACH procedure for the initial BWP of the RUL. For example, the WTRU may be configured to perform SR for the SUL when the WTRU determines that D-SR for the RUL was not successful. The WTRU may be configured to revert to the default BWP of the RUL when the WTRU determines that SR was not successful in the SUL. The WTRU may then initiate a random access procedure for the RUL of the cell.

[0139] FIG. 8 is a flowchart 800 of an example procedure for transmitting an SR by a WTRU. As shown in FIG. 8, the WTRU may be configured 802 with dedicated resources for SR (D-SR) on the RUL or on the SUL. In one embodiment, the resources may be pre-configured, or alternatively, the resources may be received for the network. The WTRU may transmit 804 on one or more dedicated resources, and if the transmission is unsuccessful, the WTRU may increment a count corresponding to the maximum number of transmission resources. If the maximum number of resources is reached 806, the WTRU may activate the SUL 808. The WTRU may then decide to transmit the SR using a random access procedure or to transmit the SR on the dedicated resources of the SUL.

[0140] The WTRU may be configured to perform RA using resources of the RUL and an initial BWP for the cell when the WTRU determines that D-SR was not successful. A D-SR failure for either the RUL or SUL may lead to CBRA for the initial BWP of the RUL.

[0141] 9 is a timing diagram 900 illustrating an RA transmission of a bandwidth portion on a RUL carrier followed by an RA transmission of a bandwidth portion on an SUL carrier. A WTRU may make a first RA transmission 902 on BWP1 (first bandwidth portion) followed by a second RA transmission 904 on BWP1. The WTRU may determine that the maximum number of transmissions has been reached for BWP1 and may then switch to BWP2 (bandwidth portion 2). For example, for BWP2, there may be only a single transmission 906 before switching to BWP_N (another bandwidth portion). On BWP_N, the WTRU may make a first RA transmission 908 followed by a second RA transmission 910 and a third RA transmission 912 before determining that the maximum number of transmissions has been met for BWP_N. Once all BWPs on the RUL carrier have been made, the WTRU may switch to the SUL carrier. For the SUL carrier, the WTRU transmits 914 on BWP1 (first bandwidth portion) of the SUL, and then transmits again 916. If the maximum number of transmissions is met for BWP1 for the SUL, the WTRU may transmit a first RA transmission 918 on BWP_2 (second bandwidth portion), followed by a second transmission 920 and a third transmission 922.

[0142] An RA may always be performed using the RA resources of the initial BWP upon a failure determination, such as on another BWP, on another RA resource. The WTRU may reconfigure and / or set the initial BWP as the active BWP upon determining a failure condition. For example, the failure determination may include a determination that D-SR was not successful, a determination that the random access procedure was not successful, a determination of a radio link problem, a determination of a radio link failure, a determination that the maximum number of HARQ transmissions has been reached for a given HARQ process, and / or a determination that a measurement value is below a threshold. In one embodiment, the measurement value may indicate that the radio link quality is insufficient. Furthermore, the WTRU may initiate a random access procedure using resources associated with the initial BWP.

[0143] Although features and elements are described above in particular combinations, those skilled in the art will understand that each feature or element can be used alone or in any combination with other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware embodied in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include computer-readable recording media. Examples of computer-readable recording media include, but are not limited to, ROM (described), RAM (random access memory), registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, and optical media such as magneto-optical media, e.g., CD-ROM disks and digital versatile disks (DVDs). A processor associated with software may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer. [Explanation of symbols]

[0144] 900 Timing Diagram 902 First RA transmission 904 Second RA transmission 906 Sent 908 First RA transmission 910 Second RA transmission 912 Third RA transmission 914 Sent 916 Sent 918 First RA sent 920 Second Transmission 922 Third Transmission

Claims

1. 1. A wireless transmit / receive unit (WTRU) comprising a processor and a memory, the processor and memory comprising: Attempting to acquire a channel in a first bandwidth portion (BWP); determining that the attempt to acquire the channel in the first BWP has failed based on a maximum number of unsuccessful access attempts being reached for the first BWP; switching from the first BWP to a second BWP based on the maximum number of unsuccessful access attempts being reached for the first BWP, the first BWP being different from the second BWP; transmitting a random access (RA) preamble via the second BWP based on the maximum number of unsuccessful access attempts being reached for the first BWP; determining that an RA Response (RAR) has been successfully received via the second BWP, the RAR including uplink resources for transmission of msg3; WTRU configured to:

2. 10. The WTRU of claim 1, wherein the channel is associated with a primary cell.

3. 10. The WTRU of claim 1, wherein the channel is a channel in an unlicensed spectrum.

4. 10. The WTRU of claim 1, wherein the unsuccessful access attempt comprises an unsuccessful attempt at a random access transmission.

5. 1. A method performed by a wireless transmit / receive unit (WTRU), comprising: Attempting to acquire a channel in a first bandwidth portion (BWP); determining that the attempt to acquire the channel in the first BWP has failed based on a maximum number of unsuccessful access attempts being reached for the first BWP; and switching from the first BWP to a second BWP based on the maximum number of unsuccessful access attempts being reached on the first BWP, the first BWP being different from the second BWP; transmitting a random access (RA) preamble over the second BWP based on the maximum number of unsuccessful access attempts being reached for the first BWP; determining that a RA Response (RAR) has been successfully received via the second BWP, the RAR including uplink resources for transmission of msg3; A method comprising:

6. 6. The method of claim 5, wherein the channel is a channel in an unlicensed spectrum.

7. 6. The method of claim 5, wherein the unsuccessful access attempt comprises an unsuccessful attempt at a random access transmission.

8. 6. The method of claim 5, wherein the channel is associated with a primary cell.

9. 10. The WTRU of claim 1, wherein a RAR is received.

10. 6. The method of claim 5, wherein no RAR is received.

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