Method for supplementary uplink access in wireless system

Abstract

To provide a method for supplementary uplink access in a wireless system.SOLUTION: A method performed by a wireless transmit / receive unit (WTRU) includes transmitting a first random access (RA) preamble on a first physical random access channel (PRACH) resource of a first UL carrier to a gNB and determining that the transmission on the first PRACH resource is unsuccessful, determining that a maximum number of random access retransmission on a first uplink (UL) carrier is met, transmitting a third RA preamble on a third PRACH resource to a base station via a second UL carrier, determining an RA-RNTI for the second UL carrier at least in part by a carrier offset, and monitoring for an RAR on the basis of the RA-RNTI.SELECTED DRAWING: Figure 7

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 Art

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

Summary of the Invention

[0003] A method performed by a WTRU may include transmitting, to a gNB (next generation Node B), a first random access preamble (RA preamble) on a first PRACH (physical RA channel) resource of a first UL (uplink) carrier. The WTRU may determine that the transmission is unsuccessful and, in response, may transmit, to the gNB, a second random access preamble on a second PRACH resource on the first UL carrier. If the transmission is not successful, the WTRU may determine whether the maximum number of RA retransmissions for the first UL carrier is met. If so, the WTRU may transmit, to the gNB via a second UL carrier, a third RA preamble on a third PRACH resource. The WTRU may determine, at least in part, an RA-RNTI for the second UL carrier based on a 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 obtained from the following description given by way of example in conjunction with the accompanying drawings, in which like reference numerals indicate like elements.

Brief Description of the Drawings

[0005]

Figure 1A

Figure 1B

Figure 1C

Figure 1D

Figure 2

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Figure 5A

Figure 5B

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DETAILED DESCRIPTION OF THE INVENTION

[0006] FIG. 1A is a diagram illustrating an exemplary 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, for example, voice, data, video, messaging, broadcast, etc. to a plurality of wireless users. The communication system 100 may enable the plurality of wireless users to access the above 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, for example, CDMA (Code Division Multiple Access), TDMA (Time Division Multiple Access), FDMA (Frequency Division Multiple Access), OFDMA (Orthogonal Frequency Division Multiple Access), SC-FDMA (Single Carrier FDMA), ZT UW DTS-s OFDM (zero-tail unique-word DFT-Spread OFDM), UW-OFDM (unique word OFDM), resource block-filtered OFDM, FBMC (filter bank multicarrier), etc.

[0007] As shown in Figure 1A, the communication system 100 may include WTRUs (Wireless Transmit / Receive Units) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, the Public Switched Telephone Network (PSTN) 108, the Internet 110, and other networks 112, although embodiments may contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the 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, the WTRUs 102a, 102b, 102c, 102d may each be referred to as a “station” and / or “STA,” and may be configured to transmit and / or receive wireless signals, and may include, but are not limited to, a UE (User Equipment), a mobile station, a fixed or mobile subscriber unit, a subscription-based unit, a pager, a cellular telephone, 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 wristwatch 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 industrial and / or automated processing chains), home appliances, devices operating on commercial and / or industrial wireless networks, etc. Any of the WTRUs 102a, 102b, 102c, and 102d may be interchangeably referred to as a UE.

[0008] Furthermore, the communication system 100 may also include base station 114a and / or base station 114b. Each of base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as CN106 / 115, Internet 110, and / or other network 112. By way of example, base stations 114a, 114b may be a BTS (Base Transceiver Station), Node-B, eNode B, Home Node B, Home eNode B, gNB, NR NodeB, site controller, AP (Access Point), wireless router, etc. While base stations 114a, 114b are each depicted as a single element, it will be understood that base stations 114a, 114b may each include any number of interconnected base stations and / or network elements.

[0009] Base station 114a may further be part of RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as, for example, a BSC (Base Station Controller), an RNC (Radio Network Controller), a relay node, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, and may be referred to as a cell (not shown). The frequencies described above may be licensed spectrum, unlicensed spectrum, or a combination of licensed spectrum and unlicensed spectrum. A cell may provide wireless service coverage for a relatively fixed or possibly changing specific geographical area. Further, a cell may be divided into sectors of the cell. For example, the cell associated with base station 114a may be divided into three sectors. Thus, in one embodiment, base station 114a may include three transceivers, i.e., one for each sector of the cell. In an embodiment, base station 114a may employ MIMO (multiple-input multiple output) 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] Base stations 114a, 114b may communicate with one or more of WTRUs 102a, 102b, 102c, 102d via an air interface 116, which may be any suitable wireless communication link (e.g., RF (Radio Frequency), microwave, centimeter wave, millimeter 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 described 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 RAN104 / 113, and the WTRU102a, 102b, 102c may implement a radio technology such as UTRA (UMTS (Universal Mobile Telecommunications System) Terrestrial Radio Access) that may establish the air interfaces 115 / 116 / 117 using, for example, WCDMA (wideband CDMA). WCDMA may include communication protocols such as, for example, HSPA (High-Speed Packet Access) and / or HSPA+ (Evolved HSPA). HSPA may include HSDPA (High-Speed DL (Downlink) Packet Access) and / or HSUPA (High-Speed UL Packet Access).

[0012] In an embodiment, the base station 114a and the WTRU102a, 102b, 102c may implement a radio technology such as E-UTRA (Evolved UMTS Terrestrial Radio Access) that may establish the air interface 116 using LTE (Long Term Evolution) and / or LTE-A (LTE-Advanced) and / or LTE-A Pro (LTE-Advanced Pro).

[0013] In an embodiment, the base station 114a and the WTRU102a, 102b, 102c may implement a radio technology such as NR (New Radio) radio access that may establish the air interface 1 with NR.16

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

[0015] In other embodiments, base station 114a and WTRUs 102a, 102b, 102c may implement wireless technologies such as, for example, IEEE802.11 (i.e., WiFi (Wireless Fidelity)), IEEE802.16 (i.e., WiMAX (Worldwide Interoperability for Microwave Access)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, IS-2000 (Interim Standard 2000), IS-95 (Interim Standard 95), IS-856 (Interim Standard 856), GSM (Global System for Mobile communications), EDGE (Enhanced Data rates for GSM Evolution), GERAN (GSM EDGE), etc.

[0016] The base station 114b in FIG. 1A may be, for example, a wireless router, a Home Node B, a Home eNode B, or an access point, and may utilize any RAT suitable for facilitating wireless connections in a local area such as, for example, an office, a home, a vehicle, a campus, an industrial facility, an aerial 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 wireless technology such as IEEE 802.11 to establish a WLAN (wireless local area network). In an embodiment, the base station 114b and the WTRUs 102c, 102d may implement a wireless technology such as IEEE 802.15 to establish a WPAN (wireless personal area network). 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] RAN 104 / 113 may be in communication with CN 106 / 115 and may be any type of network configured to provide voice, data, applications, and / or VoIP (voice over internet protocol) services to one or more of WTRUs 102a, 102b, 102c, 102d. The data may have various QoS (quality of service) requirements such as, for example, different throughput requirements, latency requirements, error tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, internet connectivity, video distribution, etc., and / or may perform high-level security functions such as, for example, user authentication. Although not shown in Figure 1A, it will be understood that RAN 104 / 113 and / or CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT or a different RAT than RAN 104 / 113. For example, in addition to being connected to RAN 104 / 113 which may utilize the radio technology of NR, CN 106 / 115 may also be in communication with another RAN (not shown) that employs the radio technology of GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi.

[0018] Furthermore, CN106 / 115 may also serve as a gateway for WTRU102a, 102b, 102c, 102d to access the PSTN108, the Internet 110, and / or other networks 112. The PSTN108 may include a circuit-switched telephone network that provides POTS (plain old telephone service). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as TCP (transmission control protocol) / IP (internet protocol) in the TCP, UDP (user datagram protocol), and / or IP of the 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 that may employ the same RAT as RAN104 / 113, or a different RAT.

[0019] Some or all of the WTRU102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities (e.g., the WTRU102a, 102b, 102c, 102d may include multiple transceivers to communicate with different wireless networks via separate wireless links). For example, the WTRU102c shown in FIG. 1A may be configured to communicate with a base station 114a that may employ a cellular-based wireless technology and a base station 114b that may employ an IEEE802 wireless technology.

[0020] Figure 1B is a system diagram illustrating an exemplary WTRU 102. As shown in Figure 1B, the WTRU 102 can 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, a non-removable memory 130, a removable memory 132, a power source 134, a GPS (Global Positioning System) chipset 136, and / or other peripheral devices 138. It will be understood that the WTRU 102 can include any partial combination (sub-combination) of the above-described elements without conflicting with the embodiments.

[0021] The processor 118 can be a general-purpose processor, a dedicated processor, a conventional processor, a DSP (digital signal processor), a plurality of microprocessors, one or more microprocessors together with a DSP core, a controller, a microcontroller, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array) circuit, any other type of IC (integrated circuit), a state machine, etc. The processor 118 can perform signal coding, data processing, power control, input / output processing, and / or any other functions that enable the WTRU 102 to operate in a wireless environment. The processor 118 can be coupled to the transceiver 120 which can be coupled to the transmit / receive element 122. While Figure 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 can be integrated together in an electronic package or chip.

[0022] The transmit / receive element 122 may be configured to transmit or receive signals to / from a base station (e.g., base station 114a) via 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 signals, UV signals 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] Although the transmit / receive element 122 is depicted as a single element in FIG. 1B, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. 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 via the air interface 116.

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

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

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

[0027] Furthermore, 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 WTRU 102. In addition to or instead of information from GPS chipset 136, WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) via air interface 116 and / or may determine its location based on the timing of signals received from two or more neighboring base stations. It will be understood that WTRU 102 may obtain location information through any suitable location-determination method without departing from the embodiments.

[0028] Furthermore, processor 118 may be coupled to other peripheral devices 138 that may include one or more software modules and / or hardware modules that provide additional features, functionality, and / or wired or wireless connections. For example, peripheral devices 138 may include an accelerometer, an e-compass, a satellite transceiver, a digital camera (for photos and / or video), a USB (Universal Serial Bus) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth® module, an FM (frequency modulated) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a VR / AR (virtual reality and / or augmented reality) device, an activity tracker, etc. Peripheral devices 138 may include one or more sensors, where the sensors may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation 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] WTRU 102 may include full-duplex radio in which some or all of the transmission and reception of some or all of the signals (associated with a particular subframe, for example, with respect to both UL (for example, for transmission) and downlink (for example, 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 (such as a choke) or by signal processing by a processor (such as a separate processor (not shown) or by processor 118). In an embodiment, WRTU 102 may include half-duplex radio for some or all of the transmission and reception of some or all of the signals (associated with a particular subframe, for example, with respect to either UL (for example, for transmission) or downlink (for example, for reception)).

[0030] FIG. 1C is a system diagram illustrating RAN 104 and CN 106 according to an embodiment. As described above, RAN 104 may employ the radio technology of E-UTRA to communicate with WTRU 102a, 102b, 102c via air interface 116. Further, RAN 104 may also be in communication with CN 106.

[0031] RAN 104 may include eNode-Bs 160a, 160b, 160c, but it will be understood that RAN 104 may include any number of eNode-Bs as long as it is consistent with the embodiments. Each of eNode-Bs 160a, 160b, 160c may include one or more transceivers to communicate with WTRU 102a, 102b, 102c via air interface 116. In one embodiment, eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, for example, eNode-B 160a may use multiple antennas to transmit and / or receive wireless signals to / from WTRU 102a.

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

[0033] CN 106 shown in FIG. 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-described elements is depicted as part of CN 106, it will be understood that any of the elements described above may be owned and / or operated by an entity other than the CN operator.

[0034] MME 162 may be connected to each of eNode-Bs 162a, 162b, and 162c in RAN 104 via the S1 interface and may act as a control node. For example, MME 162 may be responsible for authenticating users of WTRUs 102a, 102b, 102c, activating / deactivating bearers, selecting a particular serving gateway during the initial connection of WTRUs 102a, 102b, 102c, etc. MME 162 may provide control plane functions for handovers between RAN 104 and other RANs (not shown) that employ other radio technologies such as, for example, GSM and / or WCDMA.

[0035] SGW164 may be connected to each of eNode Bs 160a, 160b, and 160c in RAN104 via the S1 interface. Generally, SGW164 may route and forward user data packets to WTRUs 102a, 102b, and 102c. SGW164 may perform other functions such as, for example, fixing the user plane during eNode B handovers, triggering paging when DL data is available to WTRUs 102a, 102b, and 102c, and managing and storing the contexts of WTRUs 102a, 102b, and 102c.

[0036] SGW164 may be connected to a PGW166 that may provide access to a packet switched network, such as the Internet 110, etc., to facilitate communication between WTRUs 102a, 102b, and 102c and IP-enabled devices.

[0037] CN106 may facilitate communication with other networks. For example, CN106 may provide access to a circuit switched network, such as PSTN 108, etc., to facilitate communication between WTRUs 102a, 102b, and 102c and communication devices of a conventional land communication line. For example, CN106 may include, or may communicate with, an IP gateway (such as an IMS (IP Multimedia Subsystem) server) that serves as an interface between CN106 and PSTN 108. Additionally, CN106 may provide access to other networks 112 that may include other wired and / or wireless networks owned and / or operated by other service providers to WTRUs 102a, 102b, and 102c.

[0038] The WTRU is described as a wireless terminal in FIGS. 1A - 1D, but in certain representative embodiments, it is contemplated that the terminal may (e.g., temporarily or permanently) use a wired communication interface to a communication network.

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

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

[0041] HT (High Throughput) STAs may use a 40 MHz wide channel for communication by, for example, combining a 20 MHz primary channel with an adjacent or non - adjacent 20 MHz channel to form a 40 MHz wide channel.

[0042] A VHT (Very High Throughput) STA may support channels with widths of 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz. 40 MHz and / or 80 MHz channels may be composed by combining contiguous 20 MHz channels. A 160 MHz channel may be composed by combining eight contiguous 20 MHz channels, or by combining two non - contiguous 80 MHz channels, which may be in an 80 + 80 configuration. Regarding the 80 + 80 configuration, data may proceed to a segment parser that may split the data into two streams after channel encoding. 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] The sub-1GHz mode of operation is supported by 802.11af and 802.11ah. The channel operating bandwidth, and carriers, are reduced in 802.11af and 802.11ah compared to that used in 802.11n and 802.11ac. 802.11af supports bandwidths of 5MHz, 10MHz, and 20MHz in the spectrum of TVWS (TV white space), and 802.11ah supports bandwidths of 1MHz, 2MHz, 4MHz, 8MHz, and 16MHz using non-TVWS (non-TV white space) spectrum. According to an exemplary embodiment, 802.11ah may support Meter Type Control / Machine-Type Communication, for example, MTC devices in a macro coverage area. MTC devices may have limited performance including some performance, for example, support for some and / or limited bandwidth (e.g., only support). MTC devices may include a battery having a battery life exceeding a threshold (e.g., 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 maximum common operating bandwidth supported by all STAs in a BSS. The bandwidth of the primary channel may be set and / or restricted by the STA that supports the minimum bandwidth operating mode among all STAs operating in the BSS. In the example of 802.11ah, even if an AP and other STAs in the BSS support operating modes with 2MHz, 4MHz, 8MHz, 16MHz, and / or other channel bandwidths, the primary channel may be 1MHz wide for an STA (e.g., an MTC type device) that supports (e.g., only supports) the 1MHz mode. Carrier sensing and / or NAV (Network Allocation Vector) setting may depend on the status information of the primary channel. If the primary channel is busy due to, for example, an STA transmitting to an AP (supporting only the 1MHz operating mode), the entire available frequency band may be considered busy even if most of the frequency band remains idle and available.

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

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

[0047] RAN 113 may include gNBs 180a, 180b, 180c, although it will be understood that RAN 113 may include any number of gNBs as long as it does not conflict with the embodiment. gNBs 180a, 180b, 180c may each include one or more transceivers to communicate with WTRUs 102a, 102b, 102c via air interface 116. In one embodiment, gNBs 180a, 180b, 180c may implement MIMO technology. For example, gNBs 180a, 108b may utilize beamforming to transmit and / or receive signals to / from gNBs 180a, 180b, 180c. Thus, for example, gNB 180a may use multiple antennas to transmit a wireless signal to and / or receive a wireless signal from WTRU 102a. In an embodiment, gNBs 180a, 180b, 180c may implement carrier aggregation technology. For example, gNB 180a may transmit multiple component carriers to WTRU 102a (not shown). A subset of the component carriers described above may be on an unlicensed spectrum while the remaining component carriers may be on a licensed spectrum. In an embodiment, gNBs 180a, 180b, 180c may implement CoMP (Coordinated Multi-Point) technology. For example, WTRU 102a may receive coordinated transmission from gNB 180a and gNB 180b (and / or gNB 180c).

[0048] WTRU102a, 102b, and 102c may communicate with gNB180a, 180b, and 180c using transmissions associated with scalable numerology. For example, the OFDM symbol interval and / or the OFDM sub-carrier interval may vary for different transmissions, different cells, and / or different portions of the spectrum of the wireless transmission. WTRU102a, 102b, and 102c may communicate with gNB180a, 180b, and 180c using sub-frames or TTIs (transmission time intervals) of various or scalable lengths (e.g., including various numbers of OFDM symbols and / or absolute times of various persistent lengths).

[0049] gNBs 180a, 180b, and 180c may be configured to communicate with WTRUs 102a, 102b, and 102c in a stand-alone configuration and / or a non-stand-alone configuration. In a stand-alone configuration, WTRUs 102a, 102b, and 102c may communicate with gNBs 180a, 180b, and 180c without accessing other RANs (e.g., eNode-Bs 160a, 160b, 160c, etc.). In a stand-alone configuration, WTRUs 102a, 102b, and 102c may utilize one or more of gNBs 180a, 180b, and 180c as a mobility anchor point. In a stand-alone configuration, WTRUs 102a, 102b, and 102c may communicate with gNBs 180a, 180b, and 180c using signals in an unlicensed band. In a non-stand-alone configuration, WTRUs 102a, 102b, and 102c may communicate with / connect to gNBs 180a, 180b, and 180c while also communicating with / connected to another RAN such as eNode-Bs 160a, 160b, and 160c. For example, WTRUs 102a, 102b, and 102c may implement the principles of DC to communicate with one or more gNBs 180a, 180b, and 180c and one or more eNode-Bs 160a, 160b, and 160c substantially simultaneously. In a non-stand-alone configuration, eNode-Bs 160a, 160b, and 160c may serve as a mobility anchor for WTRUs 102a, 102b, and 102c, and gNBs 180a, 180b, and 180c may provide additional coverage and / or throughput to provide services to WTRUs 102a, 102b, and 102c.

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

[0051] CN 115 shown in FIG. 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. Each of the above elements is depicted as part of CN 115, while it will be understood that any of the elements described above may be owned and / or operated by an entity other than the CN operator.

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

[0053] SMF183a and 183b may be connected to AMF182a and 182b in CN115 via the N11 interface. Further, SMF183a and 183b may also be connected to UPF184a and 184b in CN115 via the N4 interface. SMF183a and 183b may select and control UPF184a and 184b and configure the routing of traffic passing through UPF184a and 184b. SMF183a and 183b may perform other functions such as, for example, managing and allocating the IP addresses of WTRUs, managing PDU sessions, enforcing policies and controlling QoS, and providing downlink data notifications. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0054] UPF184a and 184b may be connected to one or more of gNB180a, 180b, and 180c in RAN113 via the N3 interface and may provide access to a packet-switched network such as the Internet 110 to WTRU102a, 102b, and 102c, for example, to facilitate communication between WTRU102a, 102b, and 102c and IP-corresponding devices. UPF184a and 184b may perform other functions such as, for example, routing and forwarding packets, enforcing user plane policies, supporting multi-home PDU sessions, handling user plane QoS, buffering downlink packets, and providing mobility anchoring.

[0055] CN115 may be able to facilitate communication with other networks. For example, CN115 may include an IP gateway (e.g., an IMS (IP Multimedia Subsystem) server) that serves as an interface between CN115 and the PSTN108, or may communicate with the IP gateway. Additionally, CN115 may provide access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers, to the WTRU102a, 102b, 102c. In one embodiment, the WTRU102a, 102b, 102c may be connected to local DNs 185a, 185b through the UPF184a, 184b via an N3 interface to the UPF184a, 184b and an N6 interface between the UPF184a, 184b and the DN (Data Network) 185a, 185b.

[0056] From the perspective of FIGS. 1A-1D and the corresponding descriptions, for any of the WTRU102a-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, one or more of the functions described herein in relation to one or more of them may be performed by one or more emulation devices (not shown). An emulation device may be one or more devices configured to emulate one or more or all of the functions described herein. For example, an emulation device may be used to test other devices and / or to simulate network and / or WTRU functions.

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

[0058] One or more emulation devices may execute one or more functions, including all, while not being implemented / deployed as part of a wired and / or wireless communication network. For example, an emulation device may be utilized in a testing laboratory and / or in a testing scenario in a wired and / or wireless communication network that is not deployed (e.g., for testing) to implement testing of one or more components. One or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via an RF circuit (which may include one or more antennas, for example) may be used by an emulation device to transmit and / or receive data.

[0059] The following description is for illustrative purposes only 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 TRPs (transmission reception points) or other nodes of a radio access network. The network may include other elements as illustrated in FIGS. 1A-1D.

[0060] Mobile communication technology is constantly evolving and is on the verge of the fifth incarnation, 5G. As with previous generations, new use cases have significantly contributed to the requirements for setting up new radio systems. NR (New Radio) is a new radio technology being developed for 5G. The access air interface of NR is more flexible compared to the air interfaces 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 at least partially correspond to an NR access technology that meets 5G requirements. Embodiments are in no way limited to NR, 5G, or any other technical standard, implementation, or technology.

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

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

[0064] One design consideration for the implementation of NR includes higher transmission reliability than what may occur with legacy LTE systems. For example, the goal may be close to 99.999% transmission success and service availability. Another consideration may be support for mobility at speeds in the range of 0 to 500 km / h. At least IC and V2X may require a packet loss rate of less than 10e -6

[0065] ​The air interface should efficiently support, for example, narrowband operation using less than 200 KHz, extended battery life where, for example, autonomy reaches 15 years, and low data rates in the range of 1 to 100 kbps for small and irregular data transmissions with access latencies, for example, ranging from seconds to hours, with minimal communication overhead.

[0066] OFDM is used as the basic signal format for data transmission in both LTE and IEEE (Institute of Electrical and Electronics Engineers) 802.11 standards. Essentially, OFDM efficiently divides the spectrum into multiple parallel orthogonal sub-bands called sub-carriers. Each sub-carrier is shaped using a rectangular window in the time domain that leads to a sinc-type sub-carrier in the frequency domain. Therefore, OFDMA requires strict management of perfect frequency synchronization and uplink timing alignment within the duration of the cyclic prefix to maintain orthogonality between signals and minimize interference between carriers. Additionally, the above strict synchronization may not be very suitable in systems where a WTRU is simultaneously connected to multiple access points. Further, typically, additional power reduction is applied to uplink transmissions to ensure compliance with spectrum emission requirements in adjacent bands. The requirement to ensure compliance is particularly relevant where there is aggregation of fragmented spectrum for uplink transmissions of a WTRU.

[0067] Some of the drawbacks of CP-OFDM (conventional OFDM) may be directed by more stringent RF requirements regarding implementation, especially when operating using a large amount of continuous spectrum that does not require aggregation. Furthermore, the transmission method of CP-based OFDM may also evolve into the physical layer of the downlink for 5G similar to that of legacy systems. For example, the main modifications will likely be for the density and location of pilot signals. Therefore, further, the design of 5gFLEX (5G Flexible Radio Access Technology) may consider other waveform candidates, but conventional OFDM remains a potential candidate for 5G systems, at least regarding the downlink.

[0068] The radio access design of 5gFLEX may be characterized by a high degree of spectral flexibility that enables development in separate frequency bands with separate features, including separate duplex arrangements, continuous and discontinuous spectrum allocations, and available spectra of separate and / or variable sizes in the same or different bands. Furthermore, 5gFLEX may also support variable timing aspects, including support for multiple TTI lengths, and may support asynchronous transmission.

[0069] Duplexing schemes for both TDD (Time Division Duplex) and FDD (Frequency Division Duplex) may be supported. For FDD operation, the supplementary downlink operation may be supported using spectrum aggregation. FDD operation may support both full-duplex FDD and half-duplex FDD operations. For TDD operation, the DL / UL allocation may be dynamic. For example, it may not be based on a fixed DL / UL frame configuration. Instead, the length of the DL or UL transmission interval may be set for each transmission opportunity.

[0070] FIG. 2 is an example 200 of a WTRU 202 in a communication state with a gNB 204. Communication with the gNB 204 may include communication using a downlink carrier 206, a primary uplink carrier 208, and a SUL (supplementary uplink) carrier 210. The SUL carrier may be configured to operate supplementary to or in addition to the primary uplink carrier 208. The serving cell or gNB 204 may be configured to have one or more additional uplink carriers, for example, one or more SUL carriers. In one embodiment, the SUL 210 may be used to extend the coverage of a WTRU operating at a high frequency such that the WTRU may perform transmissions in the SUL when configured to have a lower frequency band, for example, having the primary UL carrier 208. This may be useful when the WTRU is moving towards the edge of the coverage belonging to the primary uplink carrier of the cell. 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, for example, services that provide an increase in requirements for high throughput and / or reliability. In particular, this may be possible if the WTRU is configured to perform transmissions in a plurality of uplinks that are transmitted to a related cell simultaneously or almost simultaneously, for example, in a TDM stream. As used herein, the primary uplink carrier of a WTRU may be referred to as a RUL (regular uplink) carrier. Similarly, the terms RUL carrier and NUL (normal uplink) carrier may be used interchangeably.

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

[0072] FIG. 3 is an example 300 of a plurality of bandwidth portions 304-312 constituted by a frequency band or bandwidth 302. Each bandwidth portion 304-312 may be constituted by a subset of consecutive RBs (resource blocks) on the carrier. In one embodiment, the WTRU may be limited to four simultaneously configured bandwidth portions. In other embodiments, the WTRU may be limited to more or fewer bandwidth portions. In the example shown in FIG. 3, the primary uplink carrier 316 is arranged 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 where SUL 314 is configured. Bandwidth portion 0 304 and bandwidth portion 1 306 do not have an uplink or downlink carrier configured for the WTRU.

[0073] SUL may be configured for any type of cell, including but not limited to the PCell (primary cell), the SPCell (Secondary PCell) for dual connectivity, and the SCell (secondary cell). SUL may be configured for a stand-alone system or for a cell belonging to a multi-RAT dual connectivity system.

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

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

[0076] In the second mode, RRC signaling may provide an extended, typical, and / or complete uplink configuration to a WTRU having a configuration of multiple uplink carriers. In the above case, the WTRU may have a configuration sufficient to perform transmissions of some or all types of uplinks, for example, on resources of one or more related carriers, using PUCCH (physical uplink control channel), PUSCH (physical uplink shared channel), and / or PRACH (physical random access channel). Subsequently, the WTRU may receive control signaling, for example, via a MAC CE (MAC (Media Access Control) CE (Control Element)) or DCI (downlink control information) signal to activate and / or initiate a switch between UL configurations.

[0077] Figure 4 illustrates an exemplary MAC CE command 400. In one embodiment, the MAC CE command 400 may include a header 402 indicating the addition of an SUL carrier. The data field 404 may follow the header 402 and may indicate uplink frequency information regarding the added SUL carrier. What has been described above may enable the WTRU to either activate a known SUL carrier at that frequency or add an SUL carrier at a given frequency to the configuration for later activation.

[0078] In a third mode, the RRC protocol may provide the WTRU with a plurality of uplink configurations, and two or more uplink configurations may be active either simultaneously or in a time-division stream. In one embodiment, the above mode of operation may include limitations 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 the cell simultaneously on multiple uplink carriers. In an embodiment, the above limitations may be configured for the WTRU, particularly if the performance of the WTRU indicates that the above simultaneous transmissions are not supported, for example, in one or more configured frequency bands. The types of WTRUs described above may be half-duplex WTRUs operating with a single oscillator. Alternatively or in combination, the WTRU may be characterized as an MTC type of WTRU.

[0079] Devices that may not be able to support one or more frequency bands with a wide channel bandwidth may be less complex devices, including, for example, devices for the Internet of Things (IoT). The devices described above may not be as complex as full-featured devices and may be limited to operating in one or more narrow bands.

[0080] A WTRU may be configured to have one or more BWPs (bandwidth parts) for a given cell and / or carrier. A BWP may be characterized by at least one of the following: subcarrier spacing, cyclic prefix, or number of consecutive PRBs (physical resource blocks). The characteristics described above may be aspects of the WTRU configuration and may be specified according to the performance of the WTRU. In addition, further, a BWP may be characterized by a frequency location, e.g., by a center frequency. In an embodiment, a BWP may be characterized from another frequency location, i.e., a frequency offset.

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

[0082] For example, a WTRU in CONNECTED mode may further be configured to have a default BWP. The default BWP may be the same as or different from the initial BWP. The WTRU may return to the default BWP when a timer expires, e.g., after a period of scheduling inactivity. A WTRU may be configured to have additional BWPs. For example, a WTRU may be configured to have a BWP for a specific type of data transfer, e.g., for URLLC transmission.

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

[0084] For example, the selection of UL carriers applicable when performing layer 2 procedures may depend on several factors that may be different from previous systems. This may include conditions, criteria, and triggering events for determining which of the multiple configured uplink carriers can be applied to a particular procedure. Additionally, one or more transitions in the middle of a procedure may also be affected transitions, e.g., during any of the ongoing procedures.

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

[0086] A WTRU may be configured to have one or more SUL carriers. For example, a WTRU may be configured to have multiple SULs for a given cell. Hereinafter, embodiments consider the case of a single SUL configured by a WTRU. Further, the method may also be applicable to a configuration where a WTRU is configured to have multiple SULs. In one embodiment, the SULs may be configured individually or in combination with each other. Thus, embodiments may be described using the terms SUL or SUL carrier. The embodiments described so far may be applicable to the bandwidth of the SUL, i.e., one or more SUL bands. As described above, some methods may be applied to one uplink carrier or a subset of uplink carriers. For example, first, the WTRU may first select a first subset of applicable uplink carriers based on a downlink measurement reaching a specific threshold. Next, the WTRU may make a further determination of applicable uplink carriers, for example, based on receiving downlink control scheduling. In one example, the uplink carrier may be represented as the configured uplink BWP. For example, some methods for a WTRU to make a determination of applicable UL may be based on the method used for the determination of the BWP and may also be performed in combination with other methods. In one embodiment, the determination of the BWP may be a determination related only to the uplink.

[0087] The WTRU may employ one or more different methods for the selection of RUL / SUL. For example, the method may be employed to use a static, semi-static, or dynamic determination of the applicable uplink carrier. Examples include the selection and / or activation of RUL and SUL. For example, a static method, usually by configuration or by configuration from the reception of system information and / or by pre-configuration, e.g., usually a semi-static method by L3 signaling and / or RRC control, or for example, usually a dynamic method by L1 / L2 signaling and / or L1 / MAC control may be employed. In some examples, the configuration may be pre-configured or network (NW) controlled. If NW 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 to have both RUL and SUL simultaneously. In one embodiment, the SUL may be used for the transmission of SRS. Further, thresholds may also be defined or pre-configured to determine the selection of one of RUL and SUL. Network-controlled signaling, semi-static configuration, or dynamic signaling techniques may be used to provide the selection. Using a semi-static configuration, the WTRU may be configured to have RUL and only one threshold. Later, the WTRU may be configured to have SUL based on a particular event. In one embodiment, the SRS may be configured on the SUL. The above configuration may be provided, for example, by RRC.

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

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

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

[0091] Some embodiments include the foregoing combinations. Additionally, there may be dynamic reasons for switching or for the selection of a UL carrier, which 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 the LCH (Logical Channel), service, amount of data and / or data size available for the transmission, payload, indication of a UL grant or DL allocation, RV of the transmission, speed of the WTRU, and QOS.

[0092] System-related timing may include, for example, some symbols, mini-slots, slots, sub-frames, and / or multiple sub-frames 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, signals, and / or an uplink channel, such as PUCCH, PUSCH, SRS, etc., or other uplink channel transmissions. The WTRU may perform the transmission of uplink control information, such as HARQ feedback, channel quality indication, etc., using a first carrier, such as a RUL carrier, while data transmission may be performed using resources of a second carrier, such as SUL. The separation of control information and data transmission described above may occur when the WTRU determines that it meets a certain threshold. The threshold may include considerations regarding the sub-carrier spacing (SCS) or the configuration of the LCH.

[0093] The WTRU may consider the SCS applicable to a given transmission. For example, the WTRU may perform a first transmission using the resources of a first uplink carrier configured with a first SCS, and a second transmission using the resources of a second uplink carrier configured with a second SCS as a correlation regarding the association between, for example, the type of bearer, such as an SRB (signaling radio bearer) or a DRB (data radio bearer), and the applicable SCS in terms of the configuration aspect.

[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 a group thereof, such as an LCG (Logical Channel Group) for transmitting data from the relevant LCH(s). The WTRU may determine the applicable uplink carrier when the WTRU determines that it has new data available for transmission as a correlation of the LCH associated with the data.

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

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

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

[0098] FIG. 5A depicts a 3-bit RV counter 500. In FIG. 5A, the least significant bit 504 is configured to count from 0 to 3 in decimal, i.e., from 00 to 11 in binary. In one embodiment, the WTRU may start with a redundancy version of 0. Each time the transmission goes into an error state, the WTRU may increment the RV by 1. If a rollover occurs, the leftmost bit 502 will change from 0 to 1. What has been described above may indicate a switchpoint for the use of SUL.

[0099] Figure 5B is state diagram 520 illustrating the 3-bit RV counter of Figure 5A. In one embodiment, the WTRU may change state 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 the 2-bit RV504 in the state of 0. For a failed transmission, the RV is incremented as the WTRU enters the second state 524. Then, next, the WTRU may enter the third state 526, followed by the fourth state 528 if necessary. If the WTRU enters the fourth state 528, the WTRU increments the RV, and this increment may toggle the SUL switch point 530. If the switch point described above occurs, the WTRU enters the first state 532 corresponding to the SUL and may 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 states described above represents a distinct RV where the WTRU may make an alternative or redundant transmission compared to the previous transmission in the previous state. The WTRU may loop back to the RUL after the expiration of a timer or after another event has occurred or happened.

[0100] The WTRU may perform one or more random access procedures by means of the SUL. The WTRU may initiate an RA procedure, for example, during an initial access or at the time of handover, using resources associated with an uplink carrier configured as a default uplink carrier. If the WTRU receives an indication to switch to the SUL or if a condition to switch 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 method described above, during the initial access transitioning from RRC_IDLE to RRC_CONNECTED, the following events may further be taken into consideration. The WTRU may receive, in the delivery of RMSI (remaining minimum system information), the configuration of SUL. If the received RSRP is below a threshold, the WTRU may use SUL for RACH. Otherwise, the WTRU may perform the RACH procedure by regular uplink. In addition to the switching method described above, the following trigger conditions for generating the RA procedure for SUL are as follows.

[0102] The WTRU may have a maximum retransmission count preambleTransMax_RUL for the RUL, and when this value is reached, the WTRU may switch to SUL. A different value of premableTransMax_SUL is set for SUL, and the WTRU may attempt its RACH according to the same rule.

[0103] The WTRU may be configured to have a single retransmission count (preambleTransMax) applicable to one or both of the RUL and SUL. The WTRU may alternately make attempts at RACH on the RUL and attempts at RACH on the SUL at 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, based on attempts on both the RUL and SUL, or based on individual attempts independent of the applicable uplink carrier. The WTRU may be configured to have separate parameters for each uplink carrier.

[0104] When the WTRU performs RA on the RUL, the WTRU may increase its transmission power in each attempt. The WTRU may perform beam selection for each attempt. For example, the WTRU may try different beams until the WTRU determines that the transmission is successful. In one embodiment, if P c_max reaches one or more attempts using the RUL, the WTRU may switch to the SUL. The WTRU may re-initialize the transmission power after the change of the uplink carrier, e.g., the SUL. The WTRU increases the power according to the same rule with the same or different pc_max configured with the value associated with the SUL.

[0105] Figure 6 is a flowchart 600 of a WTRU that has initiated an RA procedure. If the WTRU initiates a RACH procedure for the RUL at 602, the WTRU may receive an indication in msg2 to switch to another uplink carrier, e.g., the SUL, at 604, and the UL grant for msg3 may be applicable to the 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 the RRC_CONNECTED mode. The WTRU may determine whether the RA is performed as a contention-based procedure or not, or as a contention-free procedure or not, at 606.

[0106] During contention-free random access 606, the WTRU may 608 receive the configuration of the SUL or RUL in the HO command by means of an associated dedicated or common RACH resource. If the WTRU is configured with dedicated RACH resources for both the SUL and the RUL, the selection of the PRACH resource may depend on at least one of the RSRP of the DL beam paired to the RUL such that the WTRU transmits by means of the PRACH associated with the SUL when the RSRP falls below a configured threshold, the timing of the PRACH resource, and the requirement to beam sweep the RACH transmission. Depending on whether the WTRU needs to beam sweep the PRACH transmission either on the RUL or on the SUL, the WTRU may 610 select an appropriate carrier. For example, if the UL transmission beam may not be determined from the DL reception 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 the WTRU is configured with a dedicated RACH resource for the SUL and a common RACH resource for the RUL, the WTRU may preferentially handle the dedicated RACH resource for the SUL and may only revert to the RUL if the random access on the SUL fails. Alternatively, if the WTRU is configured with a dedicated RACH resource for the RUL and a common RACH resource for the SUL, the WTRU may preferentially handle the dedicated RACH resource for the RUL and may only revert to the SUL if the random access on the RUL fails.

[0108] For contention-based random access 612, the WTRU may select a common RACH resource associated with either RUL or SUL based on at least one of the RSRP of the target cell, 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 using resources for both RUL and SUL 616. The WTRU may use a single RA-RNTI for both resources or may calculate two separate RA-RNTIs for RUL and SUL 618. For example, the WTRU may transmit a preamble using both RUL and SUL in a way that allows the network to be able to tell that the two preambles originated from the same WTRU. For example, the WTRU may append a short signature sequence to the transmission of each preamble. What has been described above may enable the WTRU to determine an appropriate UL carrier to continue with the RA procedure. The WTRU may monitor for the RAR using two different RA-RNTIs corresponding to both transmissions on the uplink.

[0109] In another way, for transmitting a preamble on both the RUL and the SUL, the WTRU may expect, monitor, and receive a RAR corresponding to the transmission of each preamble. The RAR may provide information to the WTRU to enable the WTRU to select an appropriate grant, e.g., a UL carrier to be used for the transmission of msg3. In an example, each RAR may include quality criteria that may indicate to the WTRU whether it may continue with the RA on the RUL or whether it may use the SUL. The WTRU may transmit msg3 using the UL resources indicated in the RAR. The WTRU may transmit msg3 on the UL associated with the received first RAR. For RA in connected mode triggered by the SR procedure, or due to a timing offset for any UL, the conditions for generating an RA procedure for the SUL 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 determine whether the SR configuration in which the RA was triggered is used to distinguish the requirements for resources for the SUL. The determinations described above may be used with a WTRU that makes autonomous switching between the RUL and the SUL for PUSCH transmission. If the SR configuration in which the RA was triggered includes PUCCH resources for the SUL, the WTRU may switch to the SUL for the transmission of msg3. The WTRU may consider other situations such as the buffer status or PHR (power headroom) for each UL carrier or the timing of the SR resources when determining whether to switch to a UL carrier.

[0110] Generally, if an event that generates an RA on the SUL is triggered and the WTRU has already started 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 start a parallel RA procedure for the SUL if the WTRU has the capability or may continue a procedure by 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 selection described above is configurable. The method described above may be applicable when the selection of the PRACH resources for the RUL and SUL has a relationship that may be detectable as being the same or 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 is applicable for both carriers, the WTRU may calculate two RA-RNTIs, e.g., by applying a carrier offset to the calculation. The WTRU may determine the 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 SUL, the resources may be split into two groups, group A and group B, for example, in LTE in the case of a SpCell. Alternatively, or in combination, the grouping described above may only be maintained for RUL. If the above grouping exists, the MAC entity adds the MAC header and MAC control elements when the potential message size is required for UL data available for transmission, for example, and is larger than messageSizeGroupA, and the path loss is less than P CMAX,c -preambleInitialReceivedTargetPower-deltaPreambleMsg3-messagePowerOffsetGroupB, it may randomly select one of the PRACH resources within group B.

[0113] The estimated path loss may be obtained based on the estimated path loss of the DL carrier on 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 cannot estimate the path loss based on the DL carrier or the network explicitly indicates to the WTRU that it does not consider the path loss in the selection of the group, the MAC entity randomly selects one of the PRACH resources based only on the size of msg3.

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

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

[0117] The WTRU may be configured to have RACH resources associated with CSI-RS and NR-SS respectively. The WTRU may measure the beams associated with the reference signals described above. If the measured quality exceeds a certain threshold, the WTRU may first attempt on a dedicated RACH resource (regardless of whether it is associated with an SSB or CSI-RS resource) and then, if necessary, fall back to a common RACH resource associated with the SSB.

[0118] The ability to measure the DL reference signals associated with each of the beams can enable the WTRU to determine beam fitness before performing the RA procedure for these beams. However, in the case of SUL in a beamformed system, the WTRU may not be able to determine the beam fitness associated with SUL.

[0119] In one or more embodiments, beamformed SUL RACH procedures without DL or UL channel information may be performed. If it is assumed that there is collocation or partial beam correspondence, cmW RACH procedures using a wider beam could be based on the reference of the mmW DL SSB. The reference may take into account the compensation of path loss between cmW and mmW. In one embodiment, beam sweeping may be employed. By sweeping the beam, the transmission of multiple msg1s may be performed by the SUL beam. In one embodiment, the transmission of SRS may be beamformed. In one embodiment, the WTRU may always use the SSB when the WTRU performs the RACH procedure for the SSB.

[0120] The SR configuration may be created in the SUL or UL context. The WTRU may use one or more SR configurations to indicate the type of UL transmission resource. The UL resource may be distinguished by whether the UL-SCH resource is in RUL or USL. The WTRU may use the SR configuration with a WTRU that makes an autonomous switch between RUL and SUL for PUSCH transmission. The above indication may be explicitly done by the gNB by selecting the SR configuration available for indicating the requirement for the UL-SCH resource on SUL compared to RUL. In the above modeling, the SR configurations of RUL and SUL are called as separate SR procedures, and each SR configuration may have an SR counter, a maximum number of SR attempts, and an SR prohibition timer.

[0121] In alternative modeling, a single SR configuration may include PUCCH resources on both 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 required. Instead, the selected PUCCH resources within the configuration are used as an implicit indication of which UL is desired. The WTRU may, in one embodiment, transmit SRs simultaneously on both RUL and SUL. What has been described above can enable higher reliability and can also enable the network to load balance between RUL and SUL.

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

[0123] Furthermore, some criteria may be used to determine which SR configuration, or which PUCCH resource within an SR configuration, should be used for a given LCH. For example, the above criteria may depend on the UL and / or DL coverage levels. In one example, a measured value of RSRP (reference signal received power) 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 HARQ operating point of the WTRU 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 an SR on a given SR configuration or on a certain PUCCH resource. Similarly, a pathloss estimate or a drop in RSRP may result in the MAC entity triggering an SR with a given SR configuration or by a certain PUCCH resource.

[0124] If the gNB configures separate SR configurations to distinguish whether the UL-SCH (uplink shared channel) resources are in 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 the RRC to release the PUCCH resource and may immediately initiate a random access. Alternatively, the MAC entity may move to another uplink SR configuration. If SR-transMax is reached for both SR configurations, the WTRU may notify the RRC to release the associated PUCCH resource and may initiate a random access.

[0125] When 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 above 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 selection between SUL and RUL for RA may be preferentially handled.

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

[0127] When a D-SR failure occurs for RUL, the SR may be triggered by SUL or SUL activation. In one way, the WTRU may activate the SUL and / or initiate an SR of the SUL resources when the WTRU determines that it has reached the maximum number of D-SR transmissions for RUL. The WTRU may execute the SR using the SUL D-SR if configured, otherwise using the random access procedure.

[0128] The failure of D-SR for a UL carrier may trigger the reconfiguration of the WTRU to the initial BWP of the cell. What has been described above may apply to any cell, with or without 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. Next, the WTRU may return to the initial BWP for the first cell. The first cell may be the cell associated with the D-SR resource. Alternatively, the first cell may be the primary cell of the WTRU. For example, the WTRU may be configured with a PCell. Alternatively, the first cell may be the primary cell of the WTRU such that it applies to a group of cells associated with the D-SR resource. 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. Next, the WTRU may initiate a RA procedure using the RA resources applicable to the initial BWP for the first cell.

[0129] The failure of D-SR for RUL may trigger the 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 described above for the first cell may be the RUL.

[0130] The failure of D-SR for SUL may trigger the 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 has occurred on the SUL and is configured to perform random access using the initial BWP of the cell, the uplink carrier described above for the first cell may be the SUL.

[0131] The contention-based random access procedure (CBRA) performed for the initial BWP may follow an SR failure. In one example, the WTRU may initiate the CBRA when starting the RA procedure using the initial BWP, for example, as determined in response to any of the aforementioned events. In one embodiment, what has been described above may only be initiated when the WTRU determines that the D-SR was not successful.

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

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

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

[0135] For any of the foregoing scenarios, it may apply to the general case of SR using any of the maximum number of transmissions of RACH, D-SR, or HARQ for grantless resources. In one example, the WTRU may execute any of the foregoing procedures when it determines that an attempt to acquire and / or use the resources of a given cell and / or carrier has not been successful. In one embodiment, the determination may be made subsequent to the maximum number of transmissions and / or after a certain amount of time has elapsed after the start of a procedure, for example, an SR procedure, a HARQ process, or a RACH procedure. The amount of time elapsed may be measured using a timer. When the timer expires, the WTRU is thus configured to operate.

[0136] In one example, the WTRU may perform any of the foregoing procedures based on a determination 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 a semi-persistent uplink grant, such as an SPS (semi-persistent scheduling) grant. For example, the configured uplink resources described above may be for grant-free transmission. For example, the configured uplink resources described above may be for transmission by receiving dynamic control information for a particular type of grant and / or resource.

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

[0138] In one scenario, first, a D-SR failure for the RUL may occur, and then, the 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 an SR for the SUL when the WTRU determines that the D-SR for the RUL has not been successful. The WTRU may be configured to return to the default BWP of the RUL when the WTRU determines that the SR has not been successful in the SUL. Next, the WTRU may initiate a random access procedure for the RUL of the cell.

[0139] Figure 8 is a flowchart 800 of an exemplary procedure for transmitting an SR by a WTRU. As shown in Figure 8, the WTRU may be configured 802 to have a D-SR (dedicated resource for 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 by one or more dedicated resources and, if the transmission is not successful, 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 808 the SUL. Next, the WTRU may decide to transmit the SR using a random access procedure or to transmit the SR by dedicated resources of the SUL.

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

[0141] Figure 9 is a timing diagram 900 illustrating RA transmission of a bandwidth portion on an SUL carrier subsequent to RA transmission of a bandwidth portion on a RUL carrier. The WTRU may perform a first RA transmission 902 on BWP1 (a 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 a switch to BWP_N (another bandwidth portion) is made. On BWP_N, the WTRU may perform 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. When all BWPs on the RUL carrier are created, the WTRU may switch to the SUL carrier. For the SUL carrier, the WTRU transmits 914 on SUL's BWP1 (the first bandwidth portion) 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 (the second bandwidth portion) followed by a second transmission 920 and a third transmission 922.

[0142] RA may always be performed using the RA resources of the initial BWP for determination of impairments on other RA resources, such as on another BWP. The WTRU may reconfigure and / or set as the active BWP for the initial BWP when determining an impairment situation. For example, the determination of the impairment above may include a determination that D-SR was unsuccessful, a determination that the random access procedure was unsuccessful, 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. Further, the WTRU may initiate a random access procedure using resources associated with the initial BWP.

[0143] Although the features and elements are described above in a particular combination, one of ordinary skill 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 incorporated 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 (read only memory), RAM (random access memory), registers, cache memory, semiconductor memory devices, such as magnetic media like internal hard disks and removable disks, magneto-optical media, and optical media like CD-ROM disks and DVDs (digital versatile disks). 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 Reference Numerals

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

Claims

1. A wireless transmit / receive unit (WTRU) comprising a processor and a memory, wherein the processor and the memory attempt to acquire a channel in a first bandwidth part (BWP), determine that the attempt to acquire the channel in the first BWP has failed based on reaching a maximum number of unsuccessful access attempts with respect to the first BWP, switch from the first BWP associated with an uplink carrier to a second BWP associated with the same uplink carrier based at least on reaching the maximum number of unsuccessful access attempts with respect to the first BWP, wherein the first BWP is a different BWP than the second BWP for the same uplink carrier, after reaching the maximum number of unsuccessful access attempts with respect to the first BWP, transmit a random access (RA) preamble via the second BWP associated with the same uplink carrier, receive a random access response (RAR) in response to the RA preamble transmitted via the second BWP characterized in that the WTRU is configured as such.

2. A method performed by a wireless transmit / receive unit (WTRU), comprising: attempting to acquire a channel in a first bandwidth part (BWP); determining that an attempt to acquire the channel in the first BWP has failed based on reaching a maximum number of unsuccessful access attempts with respect to the first BWP; switching from the first BWP associated with an uplink carrier to a second BWP associated with the same uplink carrier based at least on reaching the maximum number of unsuccessful access attempts with respect to the first BWP, wherein the first BWP is a different BWP than the second BWP for the same uplink carrier; transmitting a random access (RA) preamble via the second BWP associated with the same uplink carrier after reaching the maximum number of unsuccessful access attempts with respect to the first BWP; Receiving a random access response (RAR) in response to the RA preamble transmitted via the second BWP A method characterized by comprising the above. **Claim 3** The WTRU according to claim 1, wherein the channel is associated with a primary cell. **Claim 4** The method according to claim 2, wherein the channel is associated with a primary cell. **Claim 5** The WTRU according to claim 1, wherein an RAR is received. **Claim 6** The method according to claim 2, wherein an RAR is not received. **Claim 7** The WTRU according to claim 1, wherein the channel is a channel in an unlicensed spectrum. **Claim 8** The method according to claim 2, wherein the channel is a channel in an unlicensed spectrum. **Claim 9** The WTRU according to claim 1, wherein the unsuccessful access attempt includes an unsuccessful attempt to transmit a random access. **Claim 10** The method according to claim 2, wherein the unsuccessful access attempt includes an unsuccessful attempt to transmit a random access.

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