Channel usage indication and synchronization for LTE operation in unlicensed bands

Abstract

Systems, methods and means for LTE operation LTE-U in unlicensed spectrum are disclosed. A wireless transmit / receive unit WTRU may establish a connection with a first cell on a licensed band. The WTRU may receive a first downlink transmission from a second cell operating on an unlicensed band. The WTRU may determine that a synchronization signal from a third cell operating on an unlicensed band is transmitted using one or more resource elements. The WTRU may perform frequency and / or timing estimation based on the synchronization signal transmission. The WTRU may perform rate matching around one or more resource elements corresponding to the synchronization signal transmission. The WTRU may perform rate matching around the one or more resource elements by demapping symbols of the downlink transmission.

Description

[0001] This application is a divisional application of Chinese patent application No. 201580063144.4, filed on September 24, 2015, entitled “Channel Usage Indication and Synchronization for LTE Operation in Unlicensed Bands”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims the benefit of U.S. Provisional Patent Application No. 62 / 054,881, filed September 24, 2014; U.S. Provisional Patent Application No. 62 / 075,720, filed November 5, 2014; and U.S. Provisional Patent Application No. 62 / 203,734, filed August 11, 2015, the contents of which are incorporated herein by reference. Background Art

[0004] Cellular systems such as LTE systems use licensed spectrum. For example, an operator can obtain the right to use a portion of a frequency band in a certain geographic area to transmit and receive cellular signals through a government auction. Operators can use the licensed spectrum exclusively to provide services to their users without worrying about in-band interference from other communication systems. In contrast, unlicensed spectrum remains unclaimed and can be used by various users for various purposes using various radio access technologies (RATs). Summary of the invention

[0005] Disclosed are systems, methods, and means for LTE operation in unlicensed spectrum (LTE-U), wherein the LTE operation may include carrier aggregation in licensed and unlicensed spectrum, such as licensed assisted access (LAA). LTE-U operation may be supported through channel usage indication (e.g., busy signal) and / or synchronization (sync) signaling.

[0006] For example, a wireless transmit / receive unit (WTRU) may establish a connection with a first cell on a licensed band. The WTRU may receive a first downlink transmission. The first downlink transmission may be received from a second cell operating on an unlicensed band. The WTRU may determine that a synchronization signal transmission originating from a third cell operating on an unlicensed band is transmitted using one or more resource elements. The one or more resource elements may correspond to a portion of one or more resource blocks of a downlink transmission originating from the second cell. The synchronization signal transmission may include one or more of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH), a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS), and / or a demodulation reference signal (DMRS).

[0007] The WTRU may determine that a synchronization signal transmission originating from a third cell operating in an unlicensed frequency band is transmitted using one or more resource elements by receiving downlink control information (DCI) on a downlink physical channel. The downlink physical channel may indicate which resource elements are used for synchronization signal transmission. The WTRU may perform frequency and / or timing estimation. The frequency / timing estimation may be based on the synchronization signal transmission. The WTRU may perform demodulation and / or resource symbol scaling. The demodulation and / or resource symbol scaling may be based on the synchronization signal transmission. The WTRU may determine a power offset. The power offset may be between the synchronization signal transmission and one or more other downlink transmissions. The WTRU may determine a power level for a second downlink transmission based on the power offset.

[0008] The WTRU may perform rate matching around one or more resource elements corresponding to synchronization signal transmission. Upon receiving a downlink transmission from a second cell, the WTRU may perform rate matching around one or more resource elements. The WTRU may perform rate matching around one or more resource elements by demapping symbols of the downlink transmission. During the demapping process, one or more resource elements corresponding to the synchronization signal transmission may be skipped. The WTRU may receive a configuration from the first cell on a licensed band. The configuration may indicate which resource elements the third cell will use to transmit the synchronization signal transmission. The configuration may be received in a radio resource control (RRC) message. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1A is a system diagram of an example communication system in which one or more disclosed embodiments may be implemented;

[0010] Figure 1B Yes, you can Figure 1A A system diagram of an example wireless transmit / receive unit (WTRU) for use within the illustrated communication system;

[0011] Figure 1C Yes, you can Figure 1A a system diagram of an example radio access network and an example core network used within the illustrated communication system;

[0012] Figure 1D Yes, you can Figure 1A a system diagram of another example radio access network and another example core network for use within the illustrated communication system;

[0013] Figure 1E Yes, you can Figure 1A a system diagram of another example radio access network and another example core network for use within the illustrated communication system;

[0014] Figure 2 is a diagram showing an example authorization-assisted access deployment;

[0015] Figure 3 is a diagram showing an example eNB timeline including an initial busy signal;

[0016] Figure 4 is a diagram showing an example of 25 physical resource blocks (PRBs) shared between a busy signal and data transmission;

[0017] Figure 5 is a diagram showing an example of 25 physical resource blocks (PRBs) shared between a busy signal and data transmission;

[0018] Figure 6 is a diagram showing an example of a busy signal and data transmission in progress. DETAILED DESCRIPTION

[0019] The detailed description of the illustrative embodiments will now be described with reference to the various drawings. Although this detailed description provides specific examples of possible implementations, it should be noted that these details are intended to be illustrative and not to limit the scope of the present application.

[0020] Figure 1A 1 is a diagram of an example communication system 100 in which one or more disclosed embodiments may be implemented. The communication system 100 may be a multiple access system that provides content such as voice, data, video, messaging, broadcast, etc. to multiple wireless users. The communication system 100 allows multiple wireless users to access such content by sharing system resources including wireless bandwidth. As an example, the communication system 100 may use one or more channel access methods such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single carrier FDMA (SC-FDMA), etc.

[0021] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) such as UEs 102a, 102b, 102c, and / or 102d (which may be generally referred to as WTRUs 102), a radio access network (RAN) 103 / 104 / 105, a core network 106 / 107 / 109, a public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, but it should be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network components. Each WTRU 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. For example, the WTRUs 102a, 102b, 102c, 102d may be configured to transmit and / or receive wireless signals and may include user equipment (UE), a mobile station, a fixed or mobile subscriber unit, a pager, a cellular phone, a personal digital assistant (PDA), a smart phone, a laptop computer, a netbook, a personal computer, a wireless sensor, a consumer electronic device, and the like.

[0022] The communication system 100 may also include a base station 114a and a base station 114b. Each base station 114a, 114b may be any type of device configured to facilitate access to one or more communication networks, such as the core network 106 / 107 / 109, the Internet 110, and / or the network 112, by wirelessly interfacing with at least one of the WTRUs 102a, 102b, 102c, 102d. By way of example, the base stations 114a, 114b may be base transceiver stations (BTS), Node Bs, eNode Bs, Home Node Bs, Home eNode Bs, site controllers, access points (APs), wireless routers, and the like. Although each base station 114a, 114b is depicted as a single component, it should be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network components.

[0023] The base station 114a may be part of the RAN 103 / 104 / 105, and the RAN 103 / 104 / 105 may also include other base stations and / or network components (not shown), such as a base station controller (BSC), a radio network controller (RNC), a relay node, and the like. The base station 114a and / or the base station 114b may be configured to transmit and / or receive wireless signals within a specific geographic area called a cell (not shown). The cell may be further divided into cell sectors. For example, the cell associated with the base station 114a may be divided into three sectors. The base station 114a may include multiple (e.g., three) transceivers, for example, each transceiver corresponding to a sector of the cell. The base station 114a may use multiple-input multiple-output (MIMO) technology, whereby multiple transceivers may be used for each sector of the cell.

[0024] The base stations 114a, 114b may communicate with one or more WTRUs 102a, 102b, 102c, 102d over an air interface 115 / 116 / 117, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 115 / 116 / 117 may be established using any suitable radio access technology (RAT).

[0025] More specifically, as described above, the communication system 100 may be a multiple access system and may use one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, etc. For example, the base station 114a in the RAN 103 / 104 / 105 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), and the technology may use Wideband CDMA (WCDMA) to establish the air interface 115 / 116 / 117. WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink Packet Access (HSDPA) and / or High Speed ​​Uplink Packet Access (HSUPA).

[0026] The base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as Evolved UMTS Terrestrial Radio Access (E-UTRA), which may establish the air interface 115 / 116 / 117 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A).

[0027] The base station 114a and the WTRUs 102a, 102b, 102c may implement radio access technologies such as IEEE 802.16 (Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile Communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), and GSM EDGE (GERAN).

[0028] As an example, Figure 1AThe base station 114b in the example may be a wireless router, a Home NodeB, a Home eNodeB (eNB), or an access point, and may use any appropriate RAT to facilitate wireless connectivity in a local area, such as a business location, a residence, a vehicle, a campus, and the like. The base station 114b and the WTRUs 102c and 102d may establish a wireless local area network (WLAN) by implementing a radio technology such as IEEE 802.11. The base station 114b and the WTRUs 102c and 102d may establish a wireless personal area network (WPAN) by implementing a radio technology such as IEEE802.15. The base station 114b and the WTRUs 102c and 102d may establish a picocell or a femtocell by using a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, and the like). Figure 1A As shown, the base station 114b may be directly connected to the Internet 110. Thus, the base station 114b may not need to access the Internet 110 via the core network 106 / 107 / 109.

[0029] The RAN 103 / 104 / 105 may be in communication with a core network 106 / 107 / 109, which may be any type of network configured to provide voice, data, applications, and / or voice over Internet Protocol (VoIP) services to one or more WTRUs 102a, 102b, 102c, 102d. For example, the core network 106 / 107 / 109 may provide call control, billing services, mobile location-based services, pre-paid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions such as user authentication. Although in Figure 1A Although not shown, it will be appreciated that the RAN 103 / 104 / 105 and / or the core network 106 / 107 / 109 may be in direct or indirect communication with other RANs that employ the same RAT or a different RAT as the RAN 103 / 104 / 105. For example, in addition to being connected to the RAN 103 / 104 / 105 employing E-UTRA radio technology, the core network 106 / 107 / 109 may also be in communication with another RAN (not shown) employing GSM radio technology.

[0030] The core network 106 / 107 / 109 may also act as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer network devices that use common communication protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), and the Internet Protocol (IP) in the TCP / IP Internet protocol suite. The networks 112 may include wired or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another core network connected to one or more RANs, which may use the same RAT or a different RAT as the RAN 103 / 104 / 105.

[0031] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communication system 100 may include multi-mode capabilities, e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links. Figure 1A The illustrated WTRU 102c may be configured to communicate with the base station 114a, which may employ a cellular-based radio technology, and with the base station 114b, which may employ an IEEE 802 radio technology.

[0032] Figure 1B is a system diagram illustrating an example WTRU 102. Figure 1B As shown, the WTRU 102 may include a processor 118, a transceiver 120, a transmit / receive component 122, a speaker / microphone 124, a keyboard 126, a display / touchpad 128, a non-removable memory 130, a removable memory 132, a power supply 134, a global positioning system (GPS) chipset 136, and other peripheral devices 138. It should be appreciated that the WTRU 102 may also include any sub-combination of the foregoing components while remaining consistent with the embodiment. The base stations 114a and 114b and / or the nodes represented by the base stations 114a and 114b (such as, but not limited to, a transceiver station (BTS), a Node B, a site controller, an access point (AP), a Home Node B, an evolved Home Node B (eNode B), a Home evolved Node B (HeNB or HeNode B), a Home evolved Node B gateway, and a proxy node) may include Figure 1B Some or all of the components depicted in and described herein.

[0033] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, and the like. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it should be appreciated that the processor 118 and the transceiver 120 may be integrated into one electronic component or chip.

[0034] The transmit / receive element 122 may be configured to transmit or receive signals to or from a base station (e.g., base station 114a) via an air interface 115 / 116 / 117. For example, the transmit / receive element 122 may be (a) an antenna configured to transmit and / or receive RF signals, (b) an emitter / detector configured to transmit and / or receive IR, UV, or visible light signals, or (c) a transmitter and detector configured to transmit and receive RF and light signals. It should be appreciated that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0035] In addition, although Figure 1B 102 as a single component, but the WTRU 102 may include any number of transmit / receive components 122. More specifically, the WTRU 102 may employ MIMO technology. The WTRU 102 may include two or more transmit / receive components 122 (e.g., multiple antennas) for transmitting and receiving radio signals over the air interface 115 / 116 / 117.

[0036] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and to demodulate signals received by the transmit / receive element 122. As described above, the WTRU 102 may have multi-mode capabilities. Thus, the transceiver 120 may include multiple transceivers that allow the WTRU 102 to communicate via multiple RATs, such as UTRA and IEEE 802.11.

[0037] The processor 118 of the WTRU 102 may be coupled to the speaker / microphone 124, the keyboard 126, and / or the display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit), and may receive user input data from these components. The processor 118 may also output user data to the speaker / microphone 124, the keyboard 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store information in any suitable memory, such as a non-removable memory 130 and / or a removable memory 132. The non-removable memory 130 may include a random access memory (RAM), a read-only memory (ROM), a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, and the like. The processor 118 may access information from and store data in memories that are not physically located in the WTRU 102, such as, for example, a server or a home computer (not shown).

[0038] The processor 118 may receive power from the power source 134, and may be configured to distribute and / or control power for use by other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry cell batteries (e.g., nickel-cadmium (Ni-Cd), nickel-zinc (Ni-Zn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0039] The processor 118 may also be coupled to the GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or in lieu of the information from the GPS chipset 136, the WTRU 102 may receive location information from a base station (e.g., base stations 114a, 114b) over the air interface 116 and / or determine its location based on the timing of signals received from two or more nearby base stations. It will be appreciated that the WTRU 102 may acquire location information via any suitable positioning implementation.

[0040] The processor 118 may also be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and videos), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth module, a frequency modulation (FM) radio unit, a digital music player, a video game console module, an Internet browser, and the like.

[0041] Figure 1C 1 is an example of a system diagram of the RAN 103 and the core network 106. As described above, the RAN 103 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 115. The RAN 103 may also be in communication with the core network 106. Figure 1C As shown, the RAN 103 may include Node-Bs 140a, 140b, 140c, each of which may include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 115. Each of the Node-Bs 140a, 140b, 140c may be associated with a particular cell (not shown) within the RAN 103. The RAN 103 may also include RNCs 142a, 142b. It should be appreciated that the RAN 103 may include any number of Node-Bs and RNCs.

[0042] like Figure 1C As shown, Node B 140a, 140b can communicate with RNC 142a. In addition, Node B 140c can also communicate with RNC 142b. Node B 140a, 140b, 140c can communicate with corresponding RNC 142a, 142b via Iub interface. RNC 142a, 142b can communicate with each other via Iur interface. Each RNC 142a, 142b can be configured to control the corresponding Node B 140a, 140b, 140c connected thereto. In addition, each RNC 142a, 142b can be configured to perform or support other functions, such as outer loop power control, load control, admission control, packet scheduling, handover control, macro diversity, security function, data encryption, etc.

[0043] Figure 1CThe illustrated core network 106 may include a media gateway (MGW) 144, a mobile switching center (MSC) 146, a serving GPRS support node (SGSN) 148, and / or a gateway GPRS support node (GGSN) 150. Although each of the foregoing components are described as being part of the core network 106, it should be appreciated that entities other than the core network operator may own and / or operate any of these components.

[0044] The RNC 142a in the RAN 103 may be connected to the MSC 146 in the core network 106 via an IuCS interface. The MSC 146 may be connected to the MGW 144. The MSC 146 and the MGW 144 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices.

[0045] The RNC 142a in the RAN 103 may also be connected to the SGSN 148 in the core network 106 via an IuPS interface. The SGSN 148 may be connected to the GGSN 150. The SGSN 148 and the GGSN 150 may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0046] As described above, the core network 106 may also be connected to the networks 112, which may include other wired or wireless networks owned and / or operated by other service providers.

[0047] Figure 1D 104 and the core network 107. As described above, the RAN 104 may employ an E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. In addition, the RAN 104 may also be in communication with the core network 107.

[0048] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs. Each of the eNode-Bs 160a, 160b, 160c may include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. The eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, for example, the eNode-B 160a may use multiple antennas to transmit wireless signals to, and receive wireless signals from, the WTRU 102a.

[0049] Each eNodeB 160a, 160b, 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 uplink (UL) and / or downlink (DL), etc. Figure 1D As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0050] Figure 1D The illustrated core network 107 may include a mobility management gateway (MME) 162, a serving gateway 164, and a packet data network (PDN) gateway 166. Although each of the above components are described as being part of the core network 107, it should be appreciated that entities other than the core network operator may own and / or operate any of these components.

[0051] The MME 162 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface and may serve as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during an initial attach of the WTRUs 102a, 102b, 102c, and the like. The MME 162 may also provide a control plane function to facilitate switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM or WCDMA.

[0052] The serving gateway 164 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The serving gateway 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The serving gateway 164 may also perform other functions, such as anchoring the user plane during inter-eNode-B handovers, triggering paging when downlink data is available for the WTRUs 102a, 102b, 102c, managing and storing the context of the WTRUs 102a, 102b, 102c, and the like.

[0053] The serving gateway 164 may also be connected to the PDN gateway 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0054] The core network 107 may facilitate communications with other networks. For example, the core network 106 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks such as the PSTN 108 to facilitate communications between the WTRUs 102a, 102b, 102c and traditional land-line communications devices. As an example, the core network 107 may include or communicate with an IP gateway, such as an IP Multimedia Subsystem (IMS) server, which serves as an interface between the core network 107 and the PSTN 108. The core network 107 may also provide the WTRUs 102a, 102b, 102c with access to the networks 112, which may include other wired or wireless networks owned and / or operated by other service providers.

[0055] Figure 1E 1 is an example of a system diagram of the RAN 105 and the core network 109. The RAN 105 may be an access service network (ASN) that communicates with the WTRUs 102a, 102b, 102c over the air interface 117 by employing IEEE 802.16 radio technology. As discussed further below, communication links between the different functional entities of the WTRUs 102a, 102b, 102c, the RAN 104, and the core network 109 may be defined as reference points.

[0056] like Figure 1EAs shown, the RAN 105 may include base stations 180a, 180b, 180c and an ASN gateway 182, but it should be appreciated that the RAN 105 may include any number of base stations and ASN gateways. Each base station 180a, 180b, 180c may be associated with a particular cell (not shown) in the RAN 105, and each base station may include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 117. The base stations 180a, 180b, 180c may implement MIMO technology. Thus, for example, the base station 180a may use multiple antennas to transmit wireless signals to the WTRU 102a, and receive wireless signals from the WTRU 102a. The base stations 180a, 180b, 180c may also provide mobility management functions, such as handover triggering, tunnel establishment, radio resource management, traffic classification, quality of service (QoS) policy enforcement, and the like. The ASN gateway 182 may act as a traffic aggregation point and may be responsible for implementing paging, subscriber profile caching, routing to the core network 109, and the like.

[0057] The air interface 117 between the WTRUs 102a, 102b, 102c and the RAN 105 may be defined as an R1 reference point implementing the IEEE 802.16 specification. In addition, each of the WTRUs 102a, 102b, 102c may establish a logical interface (not shown) with the core network 109. The logical interface between the WTRUs 102a, 102b, 102c and the core network 109 may be defined as an R2 reference point, which may be used for authentication, authorization, IP host configuration management, and / or mobility management.

[0058] The communication link between each base station 180a, 180b, 180c may be defined as an R8 reference point, which includes protocols for facilitating WTRU handovers and data transfer between base stations. The communication link between the base stations 180a, 180b, 180c and the ASN gateway 182 may be defined as an R6 reference point. The R6 reference point may include protocols for facilitating mobility management based on mobility events associated with each WTRU 102a, 102b, 180c.

[0059] like Figure 1EAs shown, the RAN 105 may be connected to a core network 109. The communication link between the RAN 105 and the core network 109 may be defined as an R3 reference point, which, as an example, includes protocols for facilitating data transfer and mobility management capabilities. The core network 109 may include a mobile IP home agent (MIP-HA) 184, an authentication authorization accounting (AAA) server 186, and a gateway 188. Although each of the aforementioned components are described as being part of the core network 109, it should be understood that an entity other than the core network operator may also own and / or operate any of these components.

[0060] The MIP-HA may be responsible for IP address management and may allow the WTRUs 102a, 102b, 102c to roam between different ASNs and / or different core networks. The MIP-HA 184 may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communications between the WTRUs 102a, 102b, 102c and IP-enabled devices. The AAA server 186 may be responsible for user authentication and supporting user services. The gateway 188 may facilitate interworking with other networks. For example, the gateway 188 may provide the WTRUs 102a, 102b, 102c with access to circuit-switched networks, such as the PSTN 108, to facilitate communications between the WTRUs 102a, 102b, 102c and traditional landline communications devices. In addition, the gateway 188 may also provide the WTRUs 102a, 102b, 102c with access to the networks 112, which may include other wired or wireless networks that are owned and / or operated by other service providers.

[0061] Although in Figure 1E Not shown, but appreciated, the RAN 105 may be connected to other ASNs, and the core network 109 may be connected to other core networks. The communication link between the RAN 105 and the other ASNs may be defined as an R4 reference point, which may include protocols for coordinating the mobility of the WTRUs 102a, 102b, 102c between the RAN 105 and the other ASNs. The communication link between the core network 109 and the other core networks may be defined as an R5 reference point, which may include protocols for facilitating interworking between a home core network and a visited core network.

[0062] The use of licensed spectrum may include one or more constraints and growing communication demands (e.g., for broadband data). Unlicensed spectrum may be used for non-cellular services and / or applications, such as Wi-Fi. A portion of the unlicensed spectrum may be used by a cellular operator (e.g., to overcome one or more constraints and / or to meet communication requirements). The unlicensed spectrum (e.g., one or more frequency bands of the unlicensed spectrum) may be used for one or more purposes. The unlicensed spectrum may be used by one or more users (e.g., a cellular operator). The one or more purposes and one or more users may use multiple radio access technologies (RATs). If the unlicensed spectrum is used for one or more purposes and / or by one or more users, conflicts may occur.

[0063] LTE operation in unlicensed spectrum may be referred to as LTE unlicensed operation or LTE-U. LTE-U may be implemented alone (e.g., without support from an operator operating in a licensed band). LTE-U may be implemented in conjunction with LTE (e.g., LTE operation in licensed spectrum) and / or other technologies.

[0064] The process of extending LTE (or other licensed cellular technology) into unlicensed spectrum can be implemented in various deployment scenarios. For example, one deployment scenario can use carrier aggregation. As an example, carrier aggregation can be used to aggregate a primary (e.g., licensed) carrier and a secondary (e.g., unlicensed) carrier. The carrier aggregation deployment scenario can be referred to as "licensed assisted access" (LAA) for unlicensed spectrum.

[0065] Figure 2 is a diagram showing an example authorized assisted access deployment. The WTRU 202 may establish a connection with a primary component carrier 210 (e.g., a primary cell PCell) and one or more secondary component carriers 2121 (e.g., a secondary cell SCell). The WTRU 202 may receive one or more downlink transmissions 208 from one or more secondary component carriers 212. In LAA, the primary component carrier or serving cell 210 may be a licensed carrier. For example, the primary component carrier 210 may use a licensed spectrum (e.g., a licensed band). The one or more secondary component carriers 212 may include one or more unlicensed carriers. For example, one of the one or more secondary component carriers 212 may use an unlicensed spectrum (e.g., an unlicensed band). The PCell 210 and one or more SCells 212 may be aggregated. For example, one or more unlicensed Scells may be aggregated with zero or more authorized SCells, wherein the PCell 210 may be aggregated or not aggregated. As another example, the PCell 210 and one or more Scells 212 may belong to one eNB.

[0066] like Figure 2 As shown, the WTRU 204 can establish a connection with a primary component carrier 218 (e.g., a primary cell PCell) and one or more secondary component carriers 220 (e.g., a secondary cell SCell). The WTRU 204 can receive downlink and uplink transmissions 216 from one or more secondary component carriers 220. In LAA, the primary component carrier or service cell 218 can be a licensed carrier. For example, the primary component carrier 218 can use a licensed spectrum (e.g., a licensed band). One or more secondary component carriers 220 can include one or more unlicensed carriers. For example, one of the one or more secondary component carriers 220 can use an unlicensed spectrum (e.g., an unlicensed band). PCell 218 and SCell 220 can be aggregated. For example, one or more unlicensed SCells can be aggregated with zero or more licensed SCells, where PCell 218 can be aggregated or not. As another example, PCell 218 and one or more SCells 220 can belong to one eNB.

[0067] Deployment scenarios for LTE-U operation may include dual connectivity. As an example, dual connectivity may be used when one or more unlicensed SCells and a licensed Pcell belong to different eNBs.

[0068] Considering that the unlicensed spectrum is a shared resource of the public, deploying LTE operation in the unlicensed spectrum can address the coexistence of LTE with other unlicensed technologies (e.g., Wi-Fi) and / or coexistence with one or more other LTE operators. For example, the LTE deployment in the unlicensed spectrum can attempt to minimize interference and / or provide fairness among multiple users of the unlicensed spectrum. The LTE deployment in the unlicensed spectrum can include one or more coexistence mechanisms (e.g., listen before talk (LBT) and coexistence gaps).

[0069] In the LBT coexistence mechanism, the system node may listen to a channel (e.g., a frequency band having a certain center frequency and bandwidth). The system node may include an access point (AP), an eNode B (eNB), a user equipment (UE), a wireless transmit receive unit (WTRU), and the like. The system node may determine whether a channel (e.g., a portion of the channel) is being used. The system node may determine whether the channel is being used before performing a transmission on the channel (e.g., a portion of the channel). The system node may perform a listening process to determine whether the channel is in use. The listening process may include performing one or more measurements. The one or more measurements may include measuring the amount of energy detected in the channel.

[0070] In a coexistence gap mechanism, a system node may provide one or more gaps in a transmission. The system node may transmit on a channel or a portion of a channel. The one or more gaps in the transmission may allow other potential users to determine that the signal or a portion of the channel is free for use (e.g., all or a portion).

[0071] LTE-U may be implemented in conjunction with or without LTE. LTE-U may be implemented with or without aggregation and / or dual connectivity. LTE-U may be implemented with coexistence mechanisms.

[0072] When LTE-U is deployed and one or more coexistence mechanisms are implemented, one or more transmission, reception and / or scenario issues may occur. For example, one or more transmission gaps and / or air interface differences between LTE and other technologies (e.g., Wi-Fi) may cause one or more technical issues.

[0073] An unlicensed band (e.g., a channel) may be located between LTE licensed band boundaries. An unlicensed band or a portion of an unlicensed band may become idle (e.g., unused). When an unlicensed band or a portion of an unlicensed band is idle, the LTE system may use the unlicensed band or the portion of the unlicensed band. The LTE system may indicate (e.g., to ensure that WiFi detects LTE channel usage) usage of the unlicensed band (for example, so that WiFi does not transmit on the unlicensed band when the LTE system is using the unlicensed band).

[0074] The LTE system may be silent (e.g. when it has no channels for data). One or more WTRUs may use synchronization and / or reference signal transmissions to perform synchronization. The synchronization and / or reference signal transmissions may be available during certain periods and may not be used during other periods (e.g. when there may be no LTE transmissions / there may be silent periods).

[0075] One or more terms and phrases may be used interchangeably herein. For example, Wi-Fi, WiFi, and Wifi may be used interchangeably; system and node may be used interchangeably. eNB, cell, Scell, and Pcell may be used interchangeably. Unlicensed, License-Exempt (LE), LTE-U, and LAA may be used interchangeably. Working may be used interchangeably with transmitting and / or receiving. Component carrier may be used interchangeably with serving cell. The terms channel, frequency channel, radio channel, LE channel, and frequency band may be used interchangeably. Access channel may be used interchangeably with using channel and transmitting and / or receiving on channel. Channel and LTE channel may be used interchangeably. Channel and signal may be used interchangeably. The term data / control may be used interchangeably with data and / or control signals and / or channels. Data / control may be used interchangeably with LTE data / control, data / control, and data / control channels and / or signals. eNB and LTE-UeNB may be used interchangeably. The examples described for the WTRU may be performed by and / or applicable to an eNB or other node. Likewise, examples related to UL access or UL transmission are equally applicable to DL access and / or downlink transmission.Frequency band, bandwidth and / or channel may be used interchangeably.

[0076] The LAA cell or SCell may include a cell or SCell that can use an unlicensed spectrum (e.g., a frequency band) or operate therein. The LAA cell or SCell may be associated with a corresponding PCell. For example, the LAA cell or SCell may be aggregated with the PCell. The PCell may use a licensed spectrum or operate therein. The LAA SCell may be configured for uplink and / or downlink operations. In some examples, the LAA SCell may operate in (e.g., only in) the downlink, but will not be used in the uplink.

[0077] An unlicensed channel or LAA channel may include a frequency band in the unlicensed spectrum. The WTRU and / or eNB may use the LAA channel for data, such as DL and / or UL data.

[0078] The LTE-U band (e.g., channel) can be used in an authorized assisted manner. For example, the LTE-U band can be used as or for use by an LAA SCell. An LAA SCell can support uplink transmissions. In an authorized channel, the LTE-U band can be used without assistance from a PCell. An LTE-U cell (e.g., an LTE-U PCell) can support UL and / or DL ​​transmissions.

[0079] The channel may include an LTE channel or signal (e.g., an uplink or downlink physical channel or signal). The downlink channel or signal may include a PSS, SSS, PBCH, PDCCH, EPDCCH, and / or PDSCH. The uplink channel or signal may include a PRACH, PUCCH, SRS, and / or PUSCH. The channel may include a frequency band. The channel may include a certain amount of spectrum. The certain amount of spectrum may include a center and / or carrier frequency and a bandwidth. The authorized and / or unauthorized spectrum may include one or more channels that may overlap. The control may include synchronization with respect to the one or more channels.

[0080] An LTE-U (e.g., LAA) eNB may include an eNB or cell that may transmit and / or receive one or more LTE channels (e.g., physical channels) and / or signals. An LTE-U eNB may operate (e.g., transmit and / or receive signals) in an unlicensed (LE) band. An LTE-U eNB may transmit and / or receive one or more LTE channels and / or signals in a licensed band and / or a LE band. One or more other radio access technologies (RATs) (e.g., Wi-Fi) may operate in a LE band. One or more other LTE-U eNBs and / or one or more WTRUs may operate in a LE band.

[0081] The channel usage indication and / or synchronization (sync) signal may support LTE-U operation. The channel usage indication may include a busy signal.

[0082] A busy signal may be used to acquire (e.g., reserve and / or maintain) an unlicensed channel for LTE-U operation. A busy signal may be initially sent when unlicensed channel use indicates that the channel will be used by the eNB and / or WTRU. A busy signal sent before or near the start of channel use may be referred to as an initial busy signal. As an example, while an unlicensed channel is being used, a busy signal may be used to indicate that the channel is being used by transmitting a busy signal at predetermined intervals. A busy signal sent during channel use and / or periodically during channel use to indicate that channel use will continue may be referred to as an ongoing busy signal. The busy signal may be used in a synchronous or asynchronous manner. An LTE type signal may be transmitted as a busy signal.

[0083] The busy signal may be configured (e.g., adapted and / or deployed) based on one or more of the following: static conditions, dynamically variable conditions, use of resource allocations, use of concurrent resource (e.g., PRB) sharing, and / or causing one or more busy signal transmissions to be sent between different users. The static and / or dynamically variable conditions may include channel overlap between users. One or more resource allocations may include bandwidth allocations and / or one or more physical resource block (PRB) allocations. The busy signal may be sent together with one or more data and / or control signals. One or more resources (e.g., PRBs) available for use by the busy signal, data, and / or control signal may be dynamically changed. The busy signal may indicate channel usage information.

[0084] Synchronization signals may be used to acquire and / or maintain synchronization between a WTRU and an eNB for LTE-U operation. LTE-type signals may be transmitted as LTE-U synchronization signals. Synchronization signals may be configured (e.g., adapted and / or deployed) based on one or more of the following: static conditions, dynamically variable conditions, using resource allocation, and / or using resource sharing in time and / or frequency. Synchronization signals from different eNBs may be provided (e.g., simultaneously) in a resource set. Synchronization signals from different eNBs may be provided in the same time slot and / or orthogonal frequency division multiplexing (OFDM) symbol. Synchronization signals may be extended in time and / or frequency (e.g., for reducing interference). Synchronization signals may be rate matched. Synchronization signals may include cell-specific and / or WTRU-specific configurations. Synchronization signals may be sent together with one or more data and / or control signals. One or more resources (e.g., PRBs) available for synchronization signals, busy signals, data and / or control signals may be dynamically changed. Synchronization signal transmissions (e.g., indications) may be provided with blind detection and / or without blind detection. For example, the synchronization signal transmission may be sent using one or more patterns and / or implicit indications. A synchronization signal power offset may be provided. The synchronization signal power offset may indicate a power offset between a synchronization signal and one or more other signals (eg, data signals).

[0085] Channel usage indications (e.g., busy signals) may implement LTE-U operations. For example, an eNB (e.g., an LTE-U eNB) may use a frequency band (e.g., transmit on it) during a certain period of time. The eNB may vacate the frequency band (e.g., stop using the frequency band or stop transmitting on the frequency band) during other periods of time. During the period in which the eNB uses or may use the channel, the eNB may attempt to prevent other devices (e.g., APs, other eNBs, WTRUs, etc.) from using the frequency band. The eNB may reduce interference by preventing other devices from using the frequency band. For example, other devices (e.g., APs, other eNBs, WTRUs, etc.) near the eNB may cause interference to the eNB's receiver.

[0086] LTE operation in an unlicensed bandwidth may be inconsistent with the operation of other RATs. For example, a Wi-Fi system may use an entire frequency band (e.g., a 20 or 22 MHz channel) before vacating the channel. A Wi-Fi system that uses coexistence techniques (e.g., LBT) may want other systems to operate like the Wi-Fi system (e.g., using part, all, or no channels). A Wi-Fi system that deploys LBT may perform energy detection in a small time window (e.g., 4 microseconds and / or 20 microseconds). A Wi-Fi system that deploys LBT may determine whether a frequency band is free for use. The Wi-Fi system may determine whether a frequency band is free for use by performing energy detection in a small time window. When the Wi-Fi system determines that the frequency band is free for use, the Wi-Fi system may determine to use the frequency band.

[0087] The LTE system may operate in an unlicensed band using a larger time window than the RAT (e.g., Wi-Fi) LBT measurement window. For example, an LTE subframe may be 1 millisecond. As an example, the LTE system operating bandwidth (BW) may be 5, 10, or 20 MHz. The LTE system may use a portion of the BW and / or may use different portions of the BW in different portions of the time window. For example, LTE transmissions may be performed with dynamically variable time-frequency resources. As an example, a PDSCH transmission may span one or more resource blocks (RBs), wherein the resource blocks may span the entire system bandwidth or a portion thereof. LTE transmissions may be performed over the entire subframe and / or may be performed using a subset of symbols (e.g., OFDM symbols) of the subframe. One or more reference signals (e.g., cell-specific reference signals (CRS)) may span the BW (e.g., the entire BW). One or more reference signals may be present in a subset of symbols of a subframe and / or in a subset of subcarriers on the system bandwidth.

[0088] LTE transmissions may leave one or more gaps and / or holes in frequency and / or time. Other users and / or systems (e.g., Wi-Fi systems) may interpret the one or more gaps and / or holes as indicating that the frequency band being used by the LTE-UeNB is idle. A frequency band interpreted as idle is not necessarily idle.

[0089] By allowing nodes (e.g., WTRs, eNBs, etc.) to announce channel usage, channel usage indications (e.g., busy signals) can be used to facilitate LTE-U operation. For example, an eNB (e.g., an LTE-U eNB) and / or a WTRU may transmit a signal (e.g., a channel usage indicator or a busy signal). The signal may be transmitted in the entire frequency band or in a portion of the frequency band. The signal may be transmitted in a certain period of time. The signal may indicate that the frequency band is busy. The signal may be received by one or more potential users of the frequency band. As an example, when the frequency band is in use (e.g., transmission and / or reception is being performed in the entire channel or in a portion of the channel), when the frequency band is planned to be used (e.g., transmission and / or reception is planned), and / or when the frequency band is reserved for use by the eNB and / or one or more WTRUs (e.g., scheduled and / or reserved for current and / or future transmission and / or reception), the signal may indicate that the frequency band is busy.

[0090] As an example, a busy signal may be received, measured, decoded, read, detected, and / or sensed by (as an example, or intended to be) a user or potential user of a frequency band. A device operating in the frequency band and adjacent to a device (e.g., an eNB or WTRU) transmitting a busy signal may interpret a blind signal as an indication that the channel is being used for LTE-U transmissions. When a device receives, measures, decodes, reads, detects, and / or senses a busy signal, the device may determine not to attempt to access the frequency band (e.g., transmit on it or use the frequency band). For example, an LTE-U device (e.g., an LTE-U eNB or LTE-U WTRU) may access a channel simultaneously (e.g., concurrently) with a device transmitting a busy signal.

[0091] The busy signal may have one or more characteristics described herein. The busy signal may include an initial busy signal and / or an ongoing busy signal. When a device accesses (e.g., initially uses) and / or schedules to access a frequency band, the device may send an initial busy signal. As an example, the initial busy signal may be sent after initially determining that the frequency band is idle. When the device uses the frequency band and / or schedules to maintain the frequency band, the ongoing busy signal may be sent at this time. One or more characteristics of the initial busy signal may correspond to one or more characteristics of the ongoing busy signal.

[0092] The busy signal sent by the first eNB may be transparent to the one or more WTRUs and / or the second eNB. The one or more WTRUs and / or the second eNB may not be aware of (eg, informed of) one or more of the content and / or characteristics of the busy signal.

[0093] When a device acquires and / or maintains a frequency band, the device may take action to prevent (e.g., with the intent to prevent) one or more other devices from using the frequency band. The process of acquiring and / or maintaining a frequency band may include sending an indication that the channel has and / or may have one or more of the following states: being used, scheduled to be used, or reserved for use. The process of acquiring and / or maintaining a frequency band may include using the frequency band or transmitting on the frequency band (e.g., a frequency channel). The device may acquire and / or maintain one or more frequency bands. The device may send one or more signals and / or one or more busy signals. The one or more frequency bands and / or signals may include one or more LTE channels and / or signals.

[0094] Active time for a frequency band (eg, frequency channel) may include time during which one or more signals (eg, busy signals) may be transmitted on and / or using the frequency band. The eNB may perform transmissions on the frequency band during the active time.

[0095] As an example, the WTRU may be indicated whether an LTE-U cell is active. For example, whether an LTE-U cell is active may be indicated by physical layer signaling on the LTE-U cell and / or associated or aggregated PCell and / or by the presence of a busy signal. The LTE-U cell may be active when the LTE-U cell has a frequency band and / or uses or is scheduled to use a frequency band. In one example, the indication may indicate (e.g., explicitly indicate) one or more aspects of the activity time. The one or more aspects of the activity time may include the start of the activity time, the ongoing activity time, and / or the end of the activity time. The busy signal may indicate whether the LTE-U cell is active.

[0096] The activity time may be replaced by another time (which may or may not be a specific time, as an example). For example, the LTE-U eNB may activate the LTE-U cell on demand (as an example, rather than specifying a specific activity time for the LTE-U cell). The LTE-U eNB may activate the LTE-U cell on demand based on one or more first trigger criteria. The LTE-U eNB may deactivate the LTE-U cell based on one or more second trigger criteria. The amount of time that the LTE-U cell is active may vary based on one or more criteria (e.g., an observed criterion). A busy signal during the period when the LTE-U cell is active may indicate the amount of time that the LTE-U cell is active.

[0097] The eNB may want to perform transmission and / or reception on an unlicensed band (e.g., a channel). The eNB may monitor the unlicensed band. The eNB may monitor the unlicensed channel before the unlicensed channel becomes available. One or more devices (e.g., other LTE-UeNBs, WTRUs, and / or users such as WiFi stations or APs) may contend for use of the unlicensed band. The LTE-UeNB may determine (e.g., observe) that an unlicensed channel band is available (e.g., the unlicensed band appears to be idle). When the LTE-UeNB determines that the unlicensed band is available, the LTE-UeNB may (e.g., quickly) acquire the unlicensed band. The process of acquiring the unlicensed band may include using the unlicensed band and / or indicating that the unlicensed band is busy. The LTE-UeNB may indicate that the unlicensed band is busy by using an initial busy signal.

[0098] For example, an LTE-U eNB may send an initial busy signal with synchronous and / or asynchronous timing (e.g., DL timing) for operating using and / or on an unlicensed band. The eNB may acquire the band at a time corresponding to an LTE time structure and / or an LTE time boundary (e.g., the start of an LTE symbol, time slot (TS), subframe (SF), and / or radio frame).

[0099] The busy signal timing may be based on (e.g., depending on) whether synchronous and / or asynchronous timing may be used. The eNB may use DL timing for transmission and / or as a reference for transmission on the frequency band. The eNB may use DL timing for reception on the frequency band. DL timing may include synchronous timing and / or asynchronous timing relative to other transmissions and / or timing. For example, other transmissions and / or timing may include one or more DL transmissions and / or timing of a PCell. A PCell may include an associated or aggregated PCell. As an example, other transmissions and / or timing may include one or more DL transmissions and / or timing of a previous activity time of the frequency band.

[0100] In the case of using synchronous timing, the LTE time structure and / or boundaries for the LTE-U band may correspond to the time structure and / or boundaries of the associated or aggregated PCell. The LTE time structure and / or boundaries for the LTE-U band may correspond to the time structure and / or boundaries of the previous activity time of the band (e.g., previous and / or DL ​​transmissions performed by the eNB on the band). In the case of using asynchronous timing, the LTE time structure and / or boundaries for the LTE-U band may not correspond to the time structure and / or boundaries of the associated or aggregated PCell. In the case of using asynchronous timing, the LTE time structure and / or boundaries for the LTE-U band may not correspond to the time structure and / or boundaries of the previous activity time of the band.

[0101] LTE-U eNB may use synchronized (Sync) DL timing. Synchronized DL timing may include a scenario in which the DL timing of the current active time may be aligned with (e.g., corresponds to or is synchronized with) the timing in the previous active time and / or PCell timing. The eNB may wait for the start of the next symbol, TS, SF, and / or frame to transmit one or more LTE channels (e.g., synchronization, data, and / or control channels). The start of the next symbol, TS, SF, and / or frame may correspond to the previous active time and / or PCell timing. The one or more LTE channels may be reserved for reception by one or more WTRUs (e.g., sent to the WTRU). During the waiting time, the eNB may transmit a busy signal (e.g., an initial busy signal). The busy signal may indicate to one or more users (e.g., potential users) that one or more LTE channels may not be idle.

[0102] Figure 3 An example LAAeNB timeline is shown. The example LAAeNB timeline may include the beginning of subframe n 302. The example LAAeNB timeline may include a first time 304 when the LAAeNB may first observe that the channel is idle. The example LAAeNB timeline may include a second time when the LAAeNB observes that the channel is idle for a period of time. The period may include a channel clearing time frame (e.g., 34 milliseconds). The eNB may transmit an initial busy signal. The initial busy signal may maintain the channel until the next subframe boundary. The example LAAeNB timeline may include a third time 308 at the end of subframe n and the beginning of the next subframe. The next subframe may be represented by subframe n+1. At 308, the LAAeNB may stop transmitting the initial busy signal and / or may begin transmitting data and / or control signals.

[0103] LTE-UeNB can use asynchronous (Async) DL timing. Asynchronous DL timing can correspond to a scenario in which the DL timing in the current active time may not be aligned with (e.g., corresponding to or synchronized with) the timing and / or PCell timing in the previous active time. The start time for LTE DL transmission may start when the eNB determines that the channel is idle. The start time of the LTE DL transmission may include the beginning of the first subframe for DLLTE channel transmission. The start time of the LTE DL transmission may include a timing offset. An LTE-UeNB using asynchronous DL timing can transmit an initial busy signal. As an example, when the timing offset is very small (e.g., zero and / or below the minimum WiFi idle channel assessment (CCA) cycle), the LTE-UeNB may not use and / or transmit an initial busy signal. When the timing offset is very small, one or more potential users will not see the channel idle before the LTE-UeNB starts DL transmission of one or more LTE channels.

[0104] The eNB and / or WTRU may use synchronous and / or asynchronous DL timing based on one or more eNB and / or WTRU capabilities. The use of synchronous and / or asynchronous DL timing may be configurable. The eNB may inform the WTRU (e.g., by means of signaling delivered via an associated or aggregated PCell, such as Radio Resource Control (RRC) signaling) whether synchronous and / or asynchronous DL timing may be used and / or what reference timing may be used. The reference timing may include PCell timing and / or previous activity time timing of the LTE-U cell.

[0105] The reference timing may include the previous active time timing of the LTE-U cell. The LTE-U cell may include a fixed timing schedule. The fixed timing schedule may exclude one or more effects of timing drift. If the reference timing is the previous active time timing of the LTE-U cell, then the LTE-U cell may include a fixed timing schedule. One or more signals may be sent (e.g., turned on) during the active time. One or more signals may not be sent (e.g., turned off) during the inactive time. The fixed timing schedule may remain the same during the active time and the inactive time.

[0106] The eNB may send a busy signal (eg, an initial busy signal) during a period of time. The period of time may include the time between determining that the frequency band is idle and the eNB transmitting one or more LTE channels and / or signals.

[0107] The eNB may determine whether the frequency band is idle. When the eNB determines that the frequency band is idle, the eNB may send a busy (e.g., initially busy) signal until the next LTEDL transmission opportunity. The next LTEDL transmission opportunity may include the next valid time unit (e.g., its beginning). The next valid time unit may be based on synchronized DL timing. The next LTEDL transmission opportunity may include the earliest time unit (e.g., its beginning). The WTRU may receive an LTE DL transmission in or from the earliest time unit. The WTRU may receive an LTEDL transmission, for example, when the WTRU determines that there is an LTEDL transmission. The WTRU may determine the presence of an LTEDL transmission based on blind detection and / or based on receiving an indication of its presence or impending presence.

[0108] The WTRU may receive an indication (e.g., be notified) of an upcoming LTE DL transmission on an unlicensed band (e.g., before the actual transmission). As an example, an upcoming LTE DL transmission on an unlicensed band may be indicated by an eNB or through a DL transmission indication. The DL transmission indication may be signaled on an associated or aggregated PCell. The DL transmission indication may be provided in and / or included in physical layer signaling (e.g., included in or provided by a PDCCH, EPDCCH, and / or downlink control information (DCI) format).

[0109] The time unit may include one or more of a symbol, a slot, a subframe, a frame (eg, a radio frame), and / or an LTE time unit.

[0110] The LTE-UeNB may reserve and / or acquire a frequency band by sending or transmitting a busy signal (e.g., an initial busy signal). The WTRU may detect an LTE signal (e.g., a meaningful LTE signal) and / or a DL transmission. The LTE-UeNB may reserve a frequency band by sending a busy signal until the WTRU detects an LTE signal and / or a DL transmission.

[0111] The switching time may include the time between the time when the eNB senses an idle frequency band and the time of transmission (e.g., initial busy signal transmission and / or LTE DL transmission). The switching time may be minimized. A switching time longer than a threshold may cause a potential user to determine that the channel is idle. A potential user may attempt to acquire the channel. A potential user attempting to acquire the channel may conflict with the eNB that acquires the channel. One or more conflict avoidance techniques (e.g., for reducing the possibility of a conflict) may be provided here. The one or more conflict avoidance techniques may include a backoff technique. The backoff technique may include a random waiting time before sensing the channel and / or a random amount of sensing time.

[0112] The busy signal may include one or more formats. The format of the busy signal may be transparent (e.g., unknown) to one or more WTRUs. The busy signal may be formatted as an LTE signal. For example, an eNB may transmit an LTE signal as a busy signal. One or more random samples and / or signals may be used for the busy signal.

[0113] The shortest period of the LTE signal may include an OFDM period. When a busy signal is transmitted as part of an OFDM symbol, one or more LTE-like time domain samples (e.g., similar to a CP) may be used. When a busy signal is transmitted in a portion of an OFDM symbol and in one or more complete OFDM symbols, one or more sampling level signals may be transmitted in the portion of the OFDM symbol, and one or more LTE signals may be transmitted in the one or more complete OFDM symbols. When a busy signal is transmitted in a portion of an OFDM symbol and in one or more complete OFDM symbols, one or more sampling level symbols may be transmitted in the portion of the OFDM symbol and / or in the one or more complete OFDM symbols.

[0114] One or more signals may be used for a busy signal. The one or more signals may be sent in a signal transmission. The one or more signals may be used for a portion of a busy signal. The one or more signals may include PSS, SSS, PBCH, CRS, PDCCH, and EPDCCH. Channels and / or signals used for a busy signal may be transmitted at a time and / or frequency position that is not typical for LTE. The time and / or frequency position may be repeated.

[0115] The time density of the busy signal may satisfy one or more LBT expectations of the RAT (e.g., WiFi). The busy signal may enable detection of LTE-U transmissions. For example, the busy signal may generate energy in the time window used for CCA (e.g., 20 microseconds), thereby enabling detection of LTE-U transmissions (e.g., by neighboring Wifi nodes).

[0116] The busy signal may include one or more specific static and / or dynamic configurations of bandwidth (BW) and / or physical resource blocks (PRBs). The one or more specific static and / or dynamic configurations of BW and / or PRBs may improve the deployment of the busy signal based on one or more prevailing conditions, resource allocations, and / or other dynamics.

[0117] The LTE-U eNB may send (e.g., transmit) a busy signal. The busy signal may include an initial and / or ongoing busy signal. The busy signal may prevent one or more users of the frequency band (e.g., potential users) from acquiring and / or accessing the frequency band. The one or more users of the frequency band may include one or more LTE-U eNBs, WTRUs, and / or Wi-Fi users. One or more users of the frequency band may receive a busy signal (e.g., an ongoing transmission) (e.g., sense its presence). After receiving the busy signal, one or more users of the frequency band may not use the channel. One or more users of the frequency band may use energy detection (e.g., measurement) to sense the presence of a transmission. As an example, the detected energy may correspond to interference in the BW of interest.

[0118] A user (e.g., a WiFi user) may receive (e.g., view only) a portion of an LTE-U transmission. The portion of the LTE-U transmission may include a portion of the energy of the LTE-U transmission. For example, the BW of interest to the user may partially overlap with the transmission BW of the LTE-U eNB. When the BW of interest to the user partially overlaps with the transmission BW of the LTE-U eNB, the user may determine that the BW of interest is freely accessible (as an example, even if it may not be freely accessible). The busy signal may be configured to prevent transmissions on the transmission BW of the LTE-U eNB when the BW of interest partially overlaps with the transmission BW of the LTE-U eNB.

[0119] The data BW may include the entire BW of a frequency band configured and / or used for LTE-U (e.g., for an LTE-USCell). For example, the BW may be 1.4, 3, 5, 10, 20 MHz, or other frequency ranges. The data BW may include the BW of a frequency band used for an LTE-U session. An LTE-U session may be a limited period of time for use, scheduled use, or a reserved channel for an eNB. For example, an LTE-U session may start when the eNB determines that the frequency band is idle. An LTE-U session may start when the eNB acquires the frequency band. When the eNB vacates the frequency band, the LTE-U session may end. The eNB may use the BW (e.g., use the entire BW or a portion thereof) during an LTE-U session (e.g., in each subframe of an LTE-U session). The BW may be a data BW. The data BW may be less than the entire BW of the frequency band. The eNB may configure the data BW. The eNB may indicate the data BW to one or more WTRUs. The eNB may indicate the data BW by means of signaling (e.g., physical layer and / or higher layer signaling).

[0120] The BW that the user is interested in may overlap (eg, partially overlap) with the complete BW and / or the data BW.

[0121] The LTE-U cell may transmit a busy signal within the working BW. The working BW may be the complete data BW of the LTE-U band (e.g., the LTE-U channel in use). The LTE-U cell may send a busy signal on a BW, thereby occupying a portion (e.g., some or all) of the working BW of the LTE-U band. The LTE-U cell may transmit a busy signal on a BW whose coverage exceeds the working BW of the LTE-U band. The BW whose coverage exceeds the working BW of the LTE-U band may include a maximum BW.

[0122] One or more LTE-U eNBs and / or WTRUs and / or their transceivers may operate on the same frequency band. The one or more LTE-U eNBs and / or WTRUs and / or their transceivers may follow the same channel parameter configuration (numerology). A busy signal may be transmitted within the working BW of the LTE-U band. A busy signal transmitted within the working BW of the LTE-U band may allow determination (e.g., by one or another LTE-U eNB or WTRU) that the LTE-U band is being used. As an example, one or more busy signal energy samples may be received on the working BW (e.g., calibrated working BW) of the LTE-U channel.

[0123] The LTE-U cell may send a busy signal (e.g., a portion of a busy signal) outside the configured or actual data / transmission BW (e.g., full or data BW) for the LTE-U cell. The busy signal transmission may coincide and / or overlap with all or a portion of a primary channel (e.g., frequency band) of a WiFi system such as 802.11 and / or 802.11ac. The portion of the primary channel of the WiFi system may be outside the configured or actual data / transmission BW (e.g., full or data BW) for the LTE-U cell.

[0124] The WiFi receiver can measure and / or detect a busy signal. The WiFi receiver can decode one or more signals on a primary frequency band (e.g., 20 or 22 MHz WiFi). The primary frequency band does not overlap (e.g., overlaps) with the transmission BW (e.g., full or data BW) of the LTE-U cell. The primary frequency band may overlap with busy signal transmissions outside the transmission BW of the LTE-U cell. Measuring a busy signal on the primary channel can provide higher reliability than measuring a busy signal on the auxiliary BW portion of the 802.11n and / or 802.11ac system BW that may overlap with the LTE-U transmission BW.

[0125] The busy signal may be configured to be transmitted in a frequency band, channel and / or one or more BW portions that may coincide, overlap and / or be within the LTE-U band and / or within (e.g., completely within) the BW (e.g., full or data BW) of the LTE-U band.

[0126] The busy signal may be configured to be transmitted in a frequency band, channel and / or one or more BW portions that may coincide, overlap and / or be within a BW that is larger than or outside the operating BW of the LTE-U band.

[0127] The busy signal BW may include a set of continuous physical resource blocks (PRBs). The busy signal may include discontinuous PRBs (e.g., within and / or distributed in the BW). The busy signal BW may include a fixed BW that may be independent of the data BW, such as 20 MHz or 22 MHz. The busy signal BW may include the entire BW of the frequency band. The busy signal BW may include the data BW. The busy signal BW may include a function of the complete and / or data BW, such as a certain number of PRBs that are wider than the complete or data BW. The busy signal BW may include a function of the cell ID and / or one or more other configuration parameters of the LTE-U cell. The busy signal BW may include a BW that partially or completely overlaps with the complete and / or data BW of the LTE-U frequency band. The busy signal BW may include a BW that is partially or completely outside the complete or data BW of the LTE-U frequency band.

[0128] The initial busy signal may correspond to the first BW. The ongoing busy signal may correspond to the second BW. The first BW may be equal to the second BW.

[0129] The busy signal may be transmitted on one or more PRBs. One or more PRBs may be within the busy signal BW. The busy signal may be transmitted on one or more PRB sets. The one or more PRB sets may be within the busy signal BW. The one or more PRB sets may include a set of one or more continuous and / or discontinuous PRBs.

[0130] The one or more PRBs used for the busy signal may include a function of the cell ID and / or one or more other parameters configured for the cell.

[0131] The one or more PRBs used by the eNB for busy signaling may be dynamically changeable, i.e., it may be changed per subframe and / or subframe set. For example, the eNB may use one or more PRBs with the worst and / or best channel quality for busy signaling. The eNB may measure local interference. The eNB may receive one or more interference measurements reported from one or more WTRUs. The channel quality of the one or more PRBs may be determined based on the local interference measurements and / or the reported interference measurements.

[0132] The busy signal may be sent in one or more fixed or configured PRB sets. For example, one or more PRBs may be located at or near the edge of a full or data BW. For other users or potential users, such as other LTE-U eNBs, WTRUs, and / or WiFi users, that may operate in neighboring bands that partially overlap with the full and / or data BW, the user may receive (e.g., detect) one or more busy signal PRB sets.

[0133] Figure 4 An example BW 400 of 25 PRBs is shown, which may correspond to 5 MHz (e.g., according to the authorized LTE specifications). Figure 4 In the figure, the PRBs that can be used for data transmission are shaded. The PRBs that can be allocated for busy signal transmission are not shaded. As shown, the first four and the last four PRBs can send busy signal transmission. The middle 17 PRBs can be used for data transmission.

[0134] As an example, the busy signal may cover a frequency bandwidth by including frequency hopping. The frequency bandwidth may correspond to one or more of: a fixed BW setting, a configured BW setting, and / or a data bandwidth. The frequency bandwidth may remain constant over a period of time, and / or may vary over a period of time (e.g., in accordance with a transmission setting).

[0135] Frequency hopping BW, one or more BW parts and / or PRBs for busy signal transmission enables WiFi with partial channel overlap to detect that the LTE-U band is being used.

[0136] The frequency hopping pattern and / or the signaling sequence for the busy signal may be signaled by means of one or more transmission parameters.The frequency hopping pattern and / or the signaling sequence for the busy signal may be derived from one or more transmission parameters.

[0137] As an example, one or more PRBs of a busy signal may be transmitted according to a pattern within a complete channel BW or data BW. The pattern may include one or more continuous and / or separated PRB sets. For example, a PRB set may include N1 continuous PRBs and / or N2 continuous PRBs. The N1 continuous PRBs may be used for busy signal transmission. The N2 continuous PRBs may be used for data and / or control transmission (e.g., in the case where the complete frequency band can be occupied by repeating the same pattern).

[0138] The eNB may signal the WTRU and / or other eNBs about its pattern and / or PRB usage for one or more busy signals. One or more patterns and / or PRB sets may be used for busy signals. Signaling pattern and / or PRB set usage may include signaling an indication of pattern and / or PRB set usage available for use by the eNB and / or intended for use.

[0139] Figure 5 An example BW 500 with 25 PRBs is shown, which may correspond to 5 MHz (e.g., in accordance with the authorized LTE specifications). Figure 5 In the figure, the PRBs that can be used for data transmission are shaded. The PRBs that can be allocated for busy signal transmission are not shaded. As shown, 1 PRB in every 4 PRBs can transmit a busy signal. The busy signal pattern can be represented as "1000", where "1" can represent a PRB that can be allocated for a busy signal, and "0" can represent a PRB that can transmit a data signal.

[0140] Signaling a pattern and / or PRB set usage may include signaling a bitmap. For example, the eNB may transmit and the WTRU may receive a bitmap indication of which PRBs may be used for busy and which PRBs may be used for data / control. As an example, for a BW with 25 PRBs, the bitmap indication may include 25 elements, wherein a first state of each bit (e.g., '1') may indicate that the corresponding PRB may be used for busy signaling, and a second state (e.g., '0') may indicate that the corresponding PRB may not be used for busy signaling and / or the corresponding PRB may be used for data and / or control transmission. As an example, the bitmap may be represented as 1100011000110001100011000. The bitmap may include a repeatable pattern, such as 11000.

[0141] For one or more parameters of the busy signal, such as BW, number of available PRBs (e.g., minimum or maximum number), PRB position, etc., these parameters may depend on the frequency channel on which the busy signal is transmitted. For example, the one or more parameters may depend on one or more of the channel BW, channel center frequency, and / or channel number or ID.

[0142] The ongoing busy signal may be used after the LTE-UeNB acquires the frequency band (e.g., channel) and / or after it starts transmitting. The LTE-UeNB may plan to keep the frequency band for a period of time. The period may include one or more LTE time units during which the frequency band cannot be fully used (e.g., perceived) by the LTE-UeNB and / or one or more WTRUs. One or more other users may detect (e.g., sense) that the frequency band is idle during the period. The one or more other users may transmit on the frequency band.

[0143] For example, when the eNB is not transmitting on the frequency band in the DL for one or more symbols and / or subframes (e.g., because there is no data to transmit), there may be idle LTE time units on the frequency band. When there are no active UL transmissions (e.g., PUSCH, PUCCH, and / or SRS transmissions) on the frequency band in the UL for one or more symbols and / or subframes, there may be idle LTE time units on the frequency band. There may be idle LTE time units on the frequency band when TDD UL subframes are not used (e.g., when LTE-U only supports DL). There may be idle LTE time units on the frequency band during TDD UL / DL subframe transitions.

[0144] When the strength of the transmitted signal is not strong enough to be detected by other users (e.g., as active users of the band), then the LTE time unit may be perceived as idle. Other users may include other LTE-UeNBs, WTRUs, and / or WiFi users. One or more other users may perceive the band as idle and / or may attempt to access and use the band.

[0145] When the eNB acquires a frequency band (e.g., a channel) and / or prepares to transmit or has transmitted one or more LTE signals on the frequency band, the eNB may transmit a busy-in-progress signal. Other users or potential users, such as other LTE-U eNBs, WTRUs, and / or WiFi users, may detect the busy-in-progress signal. The other users or potential users may consider the frequency band to be unavailable, which may cause the eNB to transmit a busy-in-progress signal to maintain the frequency band.

[0146] The ongoing busy signal may be transmitted at known time unit boundaries. The LTE-U eNB may send the ongoing busy signal in LTE time units. The LTE time units may be idle or may be perceived as idle. As an example, the ongoing busy signal transmission may be followed by, for example, immediately followed by, a period for the LTE-U eNB and / or one or more connected WTRUs to perform one or more UL and / or DL ​​channel transmissions.

[0147] The ongoing busy signal may be used to reserve a frequency band (e.g., channel) for UL transmission (i.e., tx). For example, the eNB may determine whether a frequency band is idle, for example, using an LBT (e.g., measurement) technique. The eNB may acquire the frequency band. For example, the eNB may send a DL signal with a busy signal and one or more of the LTE DL channels or signals. The eNB may provide the WTRU with an UL grant in subframe n regarding UL resources in subframe n+k, where k may be 4 for FDD and may depend on the UL / DL configuration for TDD, in subframe n. As an example, the eNB may continue to transmit in DL through all or part of subframe n+k-1 in order to retain the frequency band by making it appear busy (e.g., continuously busy) until the WTRU acquires and / or uses the frequency band for UL transmission in subframe n+k. As an example, the eNB may transmit a busy signal for all or part of the time before subframe n+k when the eNB does not allow the frequency band to be retained by other means during this time. When the eNB does not have enough DL data to transmit to one or more WTRUs, the eNB may not be able to maintain the frequency band.

[0148] The busy signal may be transmitted with one or more data and / or control signals. The eNB and / or the WTRU may send a busy signal (eg, an ongoing busy signal with one or more of LTE data, control, synchronization channels and / or signals).

[0149] The busy signal transmission may be simultaneous with the data / control signal transmission. For example, when the LTE-U eNB and / or one or more connected WTRUs are not transmitting and / or receiving other signals on the frequency band, the LTE-U eNB may transmit a busy signal, such as an ongoing busy signal, on a frequency band (e.g., an unlicensed frequency channel). Operations associated with non-simultaneous ongoing busy signal transmission may be similar to initial busy signal transmission when no data and / or control channels or signals are being transmitted in the LTE-U cell or LTE-U frequency band.

[0150] The eNB may transmit a busy signal, such as an ongoing busy signal, on a frequency band (e.g., an unlicensed frequency channel), while at the same time it may transmit and / or receive DL and / or UL LTE channels and / or signals on the same frequency band (e.g., in different PRBs in the frequency band).

[0151] The one or more control channels and / or signals may include one or more synchronization channels and / or signals.

[0152] For example, the eNB may transmit a busy signal, such as an ongoing busy signal, in a PRB (e.g., one or more or all PRBs) of an LTE-U band or cell, where the PRBs are not available for transmitting data and / or control channels or signals within the full or data BW of the LTE-U band or cell.

[0153] Figure 6 An example of an ongoing busy signal transmission 600 is shown. For illustrative purposes, Figure 6 In , data signals may be shaded, and ongoing busy signals may not be shaded. The eNB may perform transmissions in a frequency band that uses a BW of N PRBs for transmission. As an example, in Figure 6 Six PRBs may be used in the example shown. The eNB may transmit data (and / or control) signals via N PRBs in one or more subframes, such as subframes n-1 and n+1. The eNB may not use all BW for data (and / or control) in a subframe, such as subframe n. In the subframe, the eNB may transmit a busy-in-progress signal in one or more PRBs, such as PRBs 3, 4, and 5 of subframe n of the figure, in which it does not transmit data (and / or control) signals. The busy-in-progress signal enables other users to detect (e.g., better detect) the transmitted signal and / or interpret the frequency band as busy, and as an example, other users will not acquire the frequency band as a result.

[0154] Regardless of whether the eNB transmits any data and / or control signals, the eNB may send a busy signal, such as an ongoing busy signal, in one or more PRB sets. The eNB may transmit a busy signal in one or more PRB sets different from the PRB sets that transmit LTE data and / or control channels.

[0155] The eNB may (e.g., always) transmit on a set of dynamically shared PRBs. The dynamically shared PRBs may be dynamically shared between a busy signal and one or more data / control signals. As an example, a transmission in a set of PRBs may include a busy signal and / or one or more data / control signals.

[0156] As an example, the ratio of busy signals to data / control signals on a PRB set may be different for different subframes. For example, the ratio of busy signals to data / control signals on a PRB set may depend on the PRBs requested, used and / or scheduled for data / control transmission. The PRB set may be the same as the busy signal PRB set.

[0157] As an example, for a PRB set designated or used for a busy signal, when no data / control signal is transmitted and / or planned to be transmitted in a subframe, the eNB may transmit a busy signal in the PRB set of the subframe.

[0158] For a PRB set designated or used for a busy signal, the eNB will not transmit a busy signal in a subframe (e.g., when the number of PRBs transmitted or planned to be transmitted in a subframe for data / control exceeds the number of PRBs in the PRB set). The eNB may allocate and / or transmit data / control signals on a subframe of PRBs in the PRB set. The data / control may act as a busy signal.

[0159] For designating or using a PRB set for a busy signal, as an example, when a non-zero number of PRBs that can be transmitted or are scheduled to be transmitted in a subframe for a data / control signal is less than the number of PRBs in the PRB set, the eNB may share the PRB set between the data / control signal and the busy signal in the subframe. The eNB may allocate and / or transmit data / control in a PRB that includes all or part of the PRBs in the PRB set. The eNB may transmit a busy signal in one or more remaining PRBs in the PRB set.

[0160] For a set of PRBs designated or used for a busy signal and another set that may contain the remaining PRBs (e.g., in a full or data BW), as an example, when the number of PRBs that can be transmitted or planned to be transmitted in a subframe for data / control exceeds the number of remaining PRBs, the eNB may share the PRB set between the busy signal and the data / control signal transmission. After allocating the PRBs in the subframe to data / control, the eNB may transmit a busy signal in one or more PRBs in the available PRB set. As an example, when there are no available PRBs after the allocation, the eNB does not transmit a busy signal.

[0161] For example, when the complete channel (or data) BW may be N (e.g., 100) PRBs, then multiple (e.g., the first X and / or the last Y) PRBs may be allocated or designated to a busy signal. For example, PRBs 0-19 and 80-99 may be allocated or designated to a busy signal. In active time, as an example, when the eNB has a frequency band or may transmit or receive a signal on the frequency band, the eNB may send a signal in multiple PRBs allocated or designated to a busy signal. The signal may be one or more of a busy signal and / or a data / control signal. As an example, Y may be 0.

[0162] For example, when the LTE-U eNB has a frequency band and has no data and / or control signals to transmit, the eNB may transmit a busy signal in the first X and / or last Y PRBs, such as PRBs 0-19 and 80-99. For example, when the LTE-U eNB has a frequency band and the eNB has a full (or data) BW (e.g., 100 PRBs) of data / control signals to transmit, the eNB does not send a busy signal, and as an example, the eNB may use all of the full (or data) BW for data / control signal transmission. The eNB may transmit a busy signal in one or more remaining PRBs not used for data / control. For example, when the LTE-U eNB has the frequency band and the eNB has a BW that is less than the complete (or data) BW of the data / control signal to be transmitted (e.g., 100 PRBs) and / or more than the BW-(X+Y) PRBs of the data / control signal to be transmitted, e.g., 90 PRBs for the data / control signal, the eNB may transmit a busy signal in PRBs 0-4 and 95-99, and transmit data / control in PRBs 5-94.

[0163] Having a frequency band may include using and / or planning to use the frequency band. During an activity time for a frequency band for an eNB, the eNB may have or may be considering having the frequency band.

[0164] The LTE-U cell may share one or more frequency resources (e.g., one or more PRB sets) with one or more other LTE-U cells and / or other users (e.g., WiFi users). The LTE-U eNB will not transmit signals on a PRB set that may be used by another LTE-U eNB.

[0165] For example, in one or more subframes, the LTE-UeNB does not use the entire BW, such as one or more or all available PRBs in a full or data BW. The LTE-UeNB may transmit LTE data, control channels, and / or signals on a first PRB set (e.g., one of the sets). The LTE-UeNB may send a busy signal on a second, for example, a specified PRB set. As an example, when there is not enough data to occupy the full or data BW, the LTE-UeNB does not use a third PRB set (e.g., a third PRB set or a set of remaining PRBs). The LTE-UeNB may share a frequency band with a second LTE-UeNB. The second LTE-UeNB may use one or more unused PRBs (e.g., a third PRB set) for communication, for example, for LTE data and / or control channels (e.g., in DL).

[0166] The band sharing arrangement may be configured by the network, for example, by OA&M signaling. The band sharing may be arranged by one or more eNBs. A first eNB may inform a second eNB that the first eNB intends to use a portion of an unlicensed band, such as in a time period and / or in one or more subframes. As an example, the first eNB may notify the second eNB of the intention via X2. The first eNB may indicate the band usage and / or the predetermined band usage in one or more of the physical layer, MAC, and RRC signaling. The second eNB may determine the intention of the first eNB by monitoring the physical layer, MAC, and RRC signaling.

[0167] The eNB can determine the use of LTE-U eNBs and / or WTRUs by monitoring one or more portions of the LTE-U band. As an example, when the eNB determines that another LTE-U eNB or LTE-U WTRU may have the band, the eNB can determine the availability of PRBs by monitoring one or more PRB subsets of the band. In particular, for example, when the eNB determines that one or more PRBs are available for use and / or sharing, the eNB can use these PRBs for DL ​​and / or UL transmissions. Available can include unused. As an example, based on the properties of OFDM or based on expected interference below a certain threshold, one or more unused PRBs can also be considered available for sharing.

[0168] For one or more LTE-U eNBs (and / or WTRUs) that may share, for example, use the unlicensed band in a subframe simultaneously, they may transmit a busy signal in the subframe. Multiple users of the band (e.g., one or more eNBs and / or WTRUs) may transmit one or more busy signals simultaneously, for example, in a specific subframe of the same or different PRB sets.

[0169] If one or more busy signals are transmitted simultaneously from different LTE-U users (e.g., eNBs and / or WTRUs) in the same set of PRBs, a stronger overall busy signal may result. Other users in the band, such as other LTE-U eNBs, WTRUs, and / or WiFi users, will detect the stronger overall busy signal. The stronger overall busy signal can protect the band from other users accessing it.

[0170] For example, a first eNB may acquire a 20 MHz frequency band (e.g., a channel) that may include 100 PRBs. The first eNB may send a first busy signal on the frequency band. The first eNB may transmit the first busy signal at the edge of the frequency band, for example, on the first and last 10 PRBs. The first eNB may transmit the first busy signal on the 1st to 10th PRBs and the 91st to 100th PRBs. The second eNB may detect and / or be informed of the presence of the first eNB. The second eNB may share one or more frequency band resources with the first eNB. The second eNB may transmit a second busy signal on the same set of PRBs as the first eNB, for example, on the 1st to 10th PRBs and the 91st to 100th PRBs. The second eNB may monitor the total received power level of each PRB on the 11th to 90th PRBs. The second eNB may identify one or more PRBs with the smallest total received power and / or interference level. The second eNB may transmit data on the identified PRBs, in particular, such as one or more PRBs with the smallest total received power and / or interference. In one example, the second eNB may be provided and / or may receive a priority PRB usage list from the first eNB. The priority PRB usage list may indicate a PRB usage priority for the first eNB to use for data transmission. The second eNB may (e.g., may only) transmit data on a PRB in the received priority PRB usage list that is used by the first eNB and has a lower (e.g., lowest) usage priority.

[0171] As an example, the eNB may use different power parameters for the busy signal in different subframes. One or more power parameters may depend on whether simultaneous transmission of the busy signal and / or data / control signals is supported in the subframe.

[0172] The center frequency (eg, channel) of the LTE-U band may be different from the WiFi channel. The center frequency of the LTE-U band may be determined based on the RAT of other users, such as the WiFi channel center frequency.

[0173] As an example, information may be conveyed in a busy signal. For example, a busy signal transmitted by an LTE-U eNB may carry information that is beneficial to other users or potential users (eg, other LTE-U eNBs or WTRUs) of the LTE-U band.

[0174] The busy signal may include a control channel, such as a PDCCH or an EPDCCH. A control channel such as a PDCCH or an EPDCCH may be used as or replace the busy signal, may be part of the busy signal, and / or may provide a function of the busy signal. For example, the busy signal may be replaced by a control channel.

[0175] A busy signal may include or otherwise convey information. For example, a busy signal may convey or indicate one or more of the following. For example, a busy signal may indicate how long, such as in how many additional subframes and / or frames, the transmitter of the busy signal may plan to keep and / or use the frequency band before releasing and / or vacating the frequency band. A busy signal may indicate how long, such as in how many subframes and / or frames, the transmitter of the busy signal has kept and / or used the frequency band before it acquired (e.g., first acquired) the frequency band. A busy signal may indicate when or how long ago the first transmission of the busy signal occurred. A busy signal may indicate how much gap time (e.g., minimum gap time) the transmitter of the busy signal may allow or plan to allow when it vacates the channel. For example, the gap time may correspond to one or more of a plurality of symbols, time slots, and / or frames. A busy signal may indicate one or more transmission parameters of data that the transmitter of the busy signal may transmit and / or plan to transmit, such as frequency or BW information. The busy signal may convey one or more transmission parameters of data transmitted by the WTRU controlled by the transmitter of the busy signal.

[0176] A busy signal, PDCCH and / or EPDCCH may convey this information. Other mechanisms besides a busy signal may be used to convey this information.

[0177] The eNB transmitting the busy signal may provide information (e.g., configuration information) related to one or more parameters of the busy signal, such as time (e.g., one or more subframes and / or frames) and / or frequency location (e.g., PRB). The eNB may provide the information to one or more WTRUs and / or eNBs in a broadcast signaling transmission and / or in a dedicated signaling transmission. The broadcast signal transmission may be sent via a PCell associated with and / or aggregated with an LTE-U cell.

[0178] The eNB may signal information to the WTRU via a PCell that may be associated or aggregated with an LTE-U cell, for example using RRC signaling. The eNB may signal information to other eNBs, for example using X2 signaling over an X2 interface.

[0179] The eNB may obtain information related to other eNBs, such as neighbor eNBs, by reading broadcast information of other eNBs.

[0180] The eNB may provide the RNTI to the WTRU and / or the eNB, such as through broadcast or dedicated signaling. The RNTIh enables the WTRU and / or the eNB to receive and / or decode the content of the busy signal.

[0181] The eNB and / or WTRU may receive and / or decode one or more contents of a busy signal transmitted by another eNB.

[0182] The eNB and / or WTRU may use this information to determine when to acquire a frequency band. For example, the eNB and / or WTRU may determine to acquire a frequency band when LTE-U users have the frequency band and simultaneous use may be allowed and / or simultaneous use is feasible. The eNB and / or WTRU may determine to acquire a frequency band when the current user will vacate the frequency band and the frequency band may be idle, and / or when or after sufficient intermittent time is allowed for other users, and so on.

[0183] The eNB and / or WTRU may use this information to determine when not to attempt to acquire the band. For example, the eNB and / or WTRU may determine not to acquire the channel when an LTE-U user may have the band and / or before a gap time for other users is exceeded, etc.

[0184] LTE-U synchronization (sync) signals may support LTE-U operation. LTE-U synchronization signals may be sent in synchronization signal transmissions. In an LTE system, an eNB may send one or more reference signals, such as CRS, in one or more (e.g., all) DL subframes. An eNB may send one or more synchronization signals in one or more DL subframes of a radio frame. An eNB may send one or more reference signals and / or one or more synchronization signals in one or more (e.g., all) radio frames.

[0185] The WTRU may receive one or more reference signals and / or synchronization signals from the eNB in ​​one or more DL subframes. The WTRU may use one or more of the reference signals and / or synchronization signals (e.g., to acquire and / or maintain frequency and / or time synchronization with the eNB).

[0186] The LTE-UeNB may use an unlicensed band (e.g., a channel) periodically and / or aperiodically. The LTE-UeNB may transmit on an unlicensed band in a first time period. The LTE-UeNB may vacate (e.g., not use) the unlicensed band during a second time period. The LTE-UeNB may alternate between transmitting on an unlicensed band and vacating the unlicensed band. As an example, due to this alternating operation, the LTE-UeNB may not transmit DL reference signals and / or synchronization signals in some subframes and / or frames. The intermittent availability of one or more DL reference and / or synchronization signals may hinder the WTRU from achieving time and / or frequency synchronization with acceptable (e.g., reasonable or sufficient) performance.

[0187] A wireless transmit / receive unit (WTRU) may establish a connection with a first cell on a licensed band. The WTRU may receive a first downlink transmission. The first downlink transmission may be received from a second cell operating on an unlicensed band. The WTRU may determine a synchronization signal transmission originating from a third cell operating on an unlicensed band using one or more resource elements. The one or more resource elements may correspond to a portion of one or more resource blocks of a downlink transmission originating from the second cell. The synchronization signal transmission may include one or more of a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH), a cell-specific reference signal (CRS), a channel state information reference signal (CSI-RS), and / or a demodulation reference signal (DMRS).

[0188] The WTRU may determine that a synchronization signal transmission originating from a third cell operating in an unlicensed band is transmitted using one or more resource elements by receiving downlink control information (DCI) on a downlink physical channel. The downlink physical channel may indicate which resource elements are used for synchronization signal transmission.

[0189] The LTE-U eNB may provide and / or transmit a signal (or set of signals) for synchronization purposes (e.g., frequency and / or timing synchronization). The signal may be used by the WTRU. The WTRU may use the signal to acquire and / or maintain frequency and / or timing synchronization with the eNB. The signal may be referred to as an "LTE-U synchronization signal" or a synchronization signal. In one example, the LTE-U synchronization signal may be different from the PSS and / or SSS used in some LTE systems. In one example, the LTE-U synchronization signal may include one or more of the PSS and / or SSS.

[0190] The LTE synchronization signal and the busy signal may be implemented and / or presented by the same signal (or signal set). The LTE synchronization signal and the busy signal may include one or more of the same signals.

[0191] The LTE-U synchronization signal may include a specific format. In one example, the time interval of the LTE-U synchronization signal may be based on one or more OFDM symbols, one or more subframes, and / or one or more frames.

[0192] For example, the LTE-U synchronization signal may appear and / or repeat in one or more OFDM symbols and / or time slots, such as in a subframe, at the beginning of a subframe, or before the beginning of a subframe. The LTE-U synchronization signal may appear and / or repeat in one or more subframes, such as in a frame.

[0193] The WTRU may receive the LTE-U synchronization signal in one or more OFDM symbols and / or time slots, for example, within a subframe, at the beginning of a subframe, or before the beginning of a subframe. The WTRU may receive the LTE-U synchronization signal in one or more subframes, for example, in a frame. The LTE-U synchronization signal may be the same, for example, may be repeated, in an OFDM symbol, time slot, and / or subframe.

[0194] For example, the LTE-U synchronization signal may be transmitted on a plurality of (e.g., two) OFDM symbols in a PRB set such as the six central PRBs and / or a plurality of PRBs. The LTE-U synchronization signal transmitted on one or more specific OFDM symbols (e.g., the first OFDM symbol) may be similar to a PSS sequence. The LTE-U synchronization signal transmitted on one or more other OFDM symbols (e.g., the second OFDM symbol) may be similar to an SSS sequence. The LTE-U synchronization signal may include one or more of a PSS, CSS, PBCH, CRS, CSI-RS, or DMRS.

[0195] As an example, before sending LTE data and / or control signals on an LTE-U band (e.g., a channel), the eNB may transmit a set of LTE-U synchronization signals on the channel in a continuous manner or a selected number of times in consecutive symbols.

[0196] The eNB may transmit and / or the WTRU may receive the LTE-U synchronization signal on one or more different frequency resources in one or more different symbols and / or subframes, for example, on different PRB sets. By transmitting the LTE-U synchronization signal on one or more different frequency resources, a higher frequency diversity gain may be provided for LTE-U synchronization signal reception.

[0197] The LTE-U synchronization signal may include one or more LTE system signals, such as PSS, SSS, PBCH (e.g., MIB), CRS, CSI-RS, DMRS, etc. The transmission of one or more LTE system signals as part of the LTE-U synchronization signal may be based on the symbols and / or symbol order of the signals in the LTE system.

[0198] LTE-U synchronization signals and data may coexist. One or more LTE-U channel resources, such as PRBs, may be shared between one or more LTE-U synchronization signals and / or one or more DL channel signals (e.g., control and / or data signals). The WTRU may receive the LTE-U synchronization signals and / or one or more DL channel signals on the same set of channel resources, such as a set of PRBs.

[0199] For LTE synchronization signal and data / control time sharing, as an example, the WTRU may receive an LTE-U synchronization signal and one or more data / control signals in the same set of PRBs. The LTE-U synchronization signal and one or more data / control signals may be received in different time slots and / or OFDM symbols.

[0200] For example, a set of PRBs may be shared between an LTE-U synchronization signal and one or more data / control signals using different time slots, where a first time slot may be allocated to the LTE-U synchronization signal and a second time slot may be allocated to the one or more data / control signals. For example, as part of a DL grant, the WTRU may receive an indication that specifies how to detect and / or decode one or more subframes. The sharing may apply to one or more subframes.

[0201] As an example, one or more different OFDM symbols may be used. The LTE-U synchronization signal may be transmitted in one or more OFDM symbols (e.g., in each one or more, time slots, subframes, and / or radio frames). In an example, one or more OFDM symbols or resource elements (REs) of one or more OFDM symbols may be used for LTE-U synchronization signal transmission. The one or more OFDM symbols and / or the REs of the one or more OFDM symbols may not be used for LTE data / control signals. For example, on the first OFDM symbol in the PDSCH region of one or more subframes, such as all subframes, the eNB may transmit and / or the WTRU may receive the LTE-U synchronization signal.

[0202] The WTRU may be configured by the eNB as to which subframes may include PRB sharing for LTE-U synchronization signals as well as data / control signals, which configuration may be done via higher layer signaling (eg, RRC signaling), for example.

[0203] As an example, the eNB may transmit and / or the WTRU may receive LTE-U synchronization signals and data / control signals in different PRBs. The different PRBs may be in the same subframe and / or time slot. The WTRU may receive the LTE-U synchronization signal in a first PRB group. The WTRU may receive (e.g., simultaneously) one or more data / control signals in a second PRB group. As an example, the WTRU may expect the LTE-U synchronization signal to be included in a subset of PRBs in the subframe.

[0204] As an example, one or more LTE-U synchronization signals may be separated by means of code division multiplexing (CDM). The first eNB and the second eNB may simultaneously send their respective LTE-U synchronization signals on the same set of resources, for example, on the same set of PRBs. One or more very nearby eNBs may cause significant interference to the reception of LTE-U synchronization signals by one or more WTRUs. The interference caused to the reception of LTE-U synchronization signals may affect the synchronization performance of one or more WTRUs. As an example, CDM may be used to reduce LTE-U synchronization signal interference between cells. Scrambling and / or orthogonal cover codes (OCC) may be used.

[0205] For example, the LTE-U synchronization signal can be extended in time and / or frequency by using an OCC. Time extension may include repeating the signal in the time domain. Each repetition of the signal may be multiplied by the bits of the corresponding OCC. Extension in frequency may include repeating the signal in one or more PRBs. Each repetition of the signal may be multiplied by the bits of the corresponding OCC. Extension in time and / or frequency may increase the number of resources allocated to the LTE-U synchronization signal, which may depend on the length of the OCC. Each eNB may use an OCC for the LTE-U synchronization signal. One or more OCCs of the one or more eNBs (e.g., eNBs that are close to each other) may be different.

[0206] The LTE-U synchronization signal may be scrambled with a predetermined sequence. The predetermined sequence may be different for different eNBs. For example, the scrambling sequence may depend on the cell ID and / or reference sequence of a specific LTE-U cell and / or associated or aggregated LTE PCell.

[0207] The LTE-U synchronization signal may be configured. The LTE-U synchronization signal configuration may be indicated. For example, the WTRU may be configured to have and / or may implicitly and / or explicitly receive one or more of the following: an identification of configured frequency and / or time resources that may be allocated and / or used for the LTE-U synchronization signal and other applicable repetition information; or an indication of the presence or imminent presence of an LTE-U synchronization signal.

[0208] LTE-U synchronization signal configuration / indication may be used to represent resource allocation and / or presence indication of an LTE-U synchronization signal. A WTRU may receive a configuration (e.g., an LTE-U synchronization signal configuration / indication). The configuration may indicate that one or more resource elements will be used by the cell to transmit asynchronous signal transmissions. Resource allocation may include repetitions. Resource allocation and / or presence indications may be provided by the eNB and / or received by the WTRU (e.g., individually or jointly). The resource allocation and / or presence indication may use the same or different signaling. For example, resource allocation may be provided by higher layer signaling. As an example, a presence indication may be provided by physical layer signaling. As an example, when the WTRU may determine the presence of an LTE-U synchronization signal using blind detection, then a presence indication may not be provided and / or used. And as an example, when an LTE-U synchronization signal may occur periodically, such as periodically or at known or configured intervals, then a presence indication may not be provided and / or used.

[0209] The LTE-U synchronization signal may include a cell-specific configuration and / or indication. The LTE-U synchronization signal resource allocation may be cell-specific. Two or more WTRUs configured with an LTE-U cell may receive the same LTE-U synchronization signal resource allocation. Two or more WTRUs configured with an LTE-U cell may expect LTE-U synchronization signals at the same time and / or frequency resource location.

[0210] The presence indication may be provided in a cell-specific manner (eg, via a DCI format with a common RNTI). As an example, the cell-specific presence indication may enable the WTRU to synchronize or maintain synchronization with an LTE-U cell even if there is no DL data for the WTRU.

[0211] The LTE-U synchronization signal may be WTRU-specific, e.g., on demand. Two or more WTRUs configured with an LTE-U cell may receive the same or different WTRU-specific LTE-U synchronization signal resource allocations. Two or more WTRUs with different resource allocations may expect LTE-U synchronization signals at different time and / or frequency locations.

[0212] The WTRU-specific LTE-U synchronization signal may be used in one or more scenarios. For example, when the LTE-U synchronization signal is beamformed and / or precoded for one or more specific WTRUs, the WTRU-specific LTE-U synchronization signal may be used. The WTRU-specific LTE-U synchronization signal may be used when a group of WTRUs are receiving the LTE-U synchronization signal so that other WTRUs that do not have the intended data do not attempt to detect and / or decode the LTE-U synchronization signal.

[0213] The presence indication may be provided in a WTRU-specific manner, such as by means of a DCI format with a WTRU-specific RNTI (e.g., C-RNTI or other RNTI) or an RNTI for a group of WTRUs. The WTRU-specific presence indication may be targeted to one or more WTRUs for which DL data is intended at or shortly after the occurrence of an LTE-U synchronization signal. Providing a WTRU-specific presence indication may enable one or more WTRUs to perform one or more measurements, report one or more measurements, and / or synchronize or maintain synchronization with an LTE-U cell.

[0214] Two or more LTE-U synchronization signal configuration / indication mechanisms may be different, and as an example, this depends on whether the WTRU supports blind detection of LTE-U synchronization signals, and / or whether the LTE-U synchronization signals occur in a periodic manner or at known or configured intervals.

[0215] For example, in the case of LAA, the WTRU may receive LTE-U synchronization signal configuration / indication from the eNB via the associated or aggregated PCell.

[0216] The WTRU may receive LTE-U synchronization signal resource allocations and / or presence indications from the PCell via physical layer and / or higher layer signaling, for example via a PCell DL grant (eg, via cross-carrier scheduling or similar mechanisms).

[0217] LTE-U synchronization signal resource allocation and / or presence indication may be included in physical layer signaling such as a DCI format on a PCell. The WTRU may monitor the DCI format on the PCell. The DCI format may indicate the presence or imminent appearance of LTE-U synchronization signals and / or LTE-U data / control signals.

[0218] The WTRU may receive a DL grant for cross-carrier scheduling of the LTE-U SCell on the PCell. The DL grant for cross-carrier scheduling may indicate to the WTRU that an LTE-U synchronization signal may be present (or may be present) on the LTE-U band. The DL grant for cross-carrier scheduling may provide the WTRU with a grant of one or more DL resources on the LTE-U band.

[0219] The WTRU may be aware of the timing relationship between the presence of the indicator and the presence of the LTE-U synchronization signal.

[0220] The LTE-U SCell may be time-shifted by a number of symbols or time slots from the granted PCell (as an example, thereby allowing the WTRU to be time synchronized with the LTE-U cell before receiving grant data).

[0221] Upon, after, or in response to receiving physical layer signaling, such as a DL grant, that may indicate the presence or imminent presence of an LTE-U synchronization signal, the WTRU may use the LTE-U synchronization signal to achieve, maintain, or correct its synchronization with the LTE-U cell. The WTRU may attempt to receive DL data in accordance with the DL grant. The attempted reception may be performed concurrently with and / or after the synchronization process. The synchronization may use the LTE-U synchronization signal.

[0222] The LTE-U synchronization signal resource allocation may be received in a DL grant (eg, indicating a predefined or preconfigured resource allocation set to be used) or through other techniques, such as by means of semi-static RRC signaling from the eNB.

[0223] As an example, the WTRU may receive an LTE-U synchronization signal according to a predefined and / or preconfigured pattern for one or more of a subframe, a time slot, an OFDM symbol, a resource element, and / or a PRB. The predefined and / or preconfigured pattern may be referred to as an LTE-U synchronization signal pattern.

[0224] The eNB may provide a configuration. The WTRU may receive the configuration via higher layer signaling such as RRC signaling. The eNB may define or may configure a set of patterns. The WTRU may receive the set of patterns via higher layer signaling. Physical layer signaling (e.g., on the PCell) may indicate which pattern is applicable at a particular time.

[0225] During the active time of the LTE-U band, the WTRU may expect the presence of an LTE-U synchronization signal in the LTE-U band (eg, channel) based on the LTE-U synchronization signal pattern.

[0226] Regardless of whether the LTE-U cell is active or inactive, the WTRU may expect the presence of an LTE-U synchronization signal in the LTE-U frequency band based on the LTE-U synchronization signal pattern.

[0227] One or more indications may be implicit. For example, the eNB may transmit an LTE-U signal and / or synchronization signal once and / or more than once every XX+YY milliseconds. XX and / or YY may be configurable values, for example, signaled by the eNB to the WTRU. YY may be 0 or may not be used.

[0228] The WTRU may be configured with a PRB set for expecting an LTE-U synchronization signal. As an example, when the WTRU does not receive an instance of an LTE-U synchronization signal after XX milliseconds from the most recent LTE-U synchronization signal and / or the start of the previous active time and / or the end of the previous active time, the WTRU may expect an LTE-U synchronization signal in subframe XX+YY from the most recent LTE-U synchronization signal and / or the start of the previous active time and / or the end of the previous active time.

[0229] The WTRU may determine (e.g., derive) one or more signal characteristics based on the most recent activity time. For example, multiple, possibly consecutive, repetitions of the LTE-U synchronization signal may be the same as the signal repetition used for the most recent activity time. Multiple, possibly consecutive, repetitions of the LTE-U synchronization signal may depend on the time that has elapsed since the most recent activity time. For example, when the elapsed time is less than a threshold (e.g., 20 milliseconds), the WTRU may expect one instance of the LTE-U synchronization signal, such as no LTE-U synchronization signal repetitions. As an example, when the elapsed time is greater than another threshold (e.g., 100 milliseconds), the WTRU may expect multiple repetitions of the LTE-U synchronization signal (e.g., 2 repetitions).

[0230] The WTRU may periodically or continuously search for and / or perform blind decoding on potential LTE-U synchronization signals. The WTRU may search for a set of possible LTE-U synchronization signals. The WTRU may derive some information from the index of the LTE-U synchronization signal in the set. For example, given that the complexity of the blind detection process increases with the number of detection scenarios, the blind detection process for the LTE-U synchronization signal may accept a limited number of waveforms.

[0231] For example, the WTRU may determine (e.g., derive) the start of one or more of an OFDM symbol, a slot, a subframe, and / or a frame for the LTE-U band. As an example, the determination may depend on the timing detected for the LTE-U synchronization signal (e.g., the WTRU's detected timing), such as asynchronous DL timing.

[0232] The LTE-U cell may share one or more frequency resources, such as one or more PRB sets, with one or more LTE-U cells and / or other users (e.g., WiFi users). Two or more eNBs may transmit LTE-U synchronization signals on the same PRB set (e.g., overlapping resources) and / or different PRB sets (e.g., non-overlapping resources).

[0233] For example, different LTE-U eNBs may transmit LTE-U synchronization signals in different PRB sets and / or different subframes. Using different PRB sets and / or different subframes for two or more synchronization signals may ensure that there is no overlap in resource usage for synchronization signal transmission.

[0234] Signals for transmission and / or reception may be rate matched around one or more channel resources. For example, an LTE-U eNB may perform rate matching around LTE-U synchronization signals of other eNBs. As an example, terms such as "rate matching" performed on and / or around one or more channel resources may be used to refer to or include transmitting or receiving in a manner that skips or does not use one or more channel resources. As an example, one or more channel resources may include one or more REs, symbols (e.g., SC-FDMA or OFDM symbols), PRBs, subcarriers, carriers, time slots, subframes, and the like.

[0235] A transmitter (e.g., an eNB or WTRU that may perform a transmission or plan to perform a transmission) may perform rate matching on a signal (e.g., a signal that is transmitted or planned to be transmitted) around one or more channel resources. For example, the WTRU may perform rate matching around one or more resource elements. Upon receiving a DL transmission, the WTRU may perform rate matching around the one or more resource elements. In an example, performing rate matching on a signal around one or more channel resources may refer to or include the transmitter not performing a transmission and / or not mapping a DL (or UL) signal in one or more channel resources and / or mapping the signal to one or more channel resources.

[0236] The WTRU may perform rate matching around one or more resource elements corresponding to synchronization signal transmission. When receiving a downlink transmission from a second cell, the WTRU may perform rate matching around one or more resource elements. The WTRU may perform rate matching around one or more resource elements by demapping symbols of the downlink transmission. One or more resource elements corresponding to the synchronization signal transmission may be skipped during the demapping process. The WTRU may receive a configuration from the first cell on a licensed band. The configuration may indicate which resource elements will be used by the third cell to transmit the synchronization signal transmission. The configuration may be received in a radio resource control (RRC) message.

[0237] A receiver (e.g., an eNB or WTRU that may perform reception or attempt to perform reception) may rate match one or more channel resources when receiving or attempting to receive a signal. Rate matching around one or more channel resources may include a process where the receiver does not expect, receive, and / or decode a DL (or UL) signal in one or more channel resources. The receiver may skip signal reception (or attempt signal reception) in one or more channel resources and / or signal demapping from one or more channel resources.

[0238] The eNB may perform rate matching around one or more LTE-U synchronization signals of one or more other eNBs. For example, the eNB may perform rate matching on DL signals (e.g., data and / or control signals such as PDSCH and / or (E)PDCCH) around one or more (e.g., all) channel resources (e.g., REs) of DL signals of one or more other eNBs (e.g., synchronization and / or busy signals of neighbor eNBs). For example, the eNB does not send DL signals on one or more channel resources that may be used by synchronization signals of neighbor eNBs (e.g., in subframes and / or frames in which the neighbor eNB may be scheduled to transmit its synchronization signal). As an example, by avoiding transmission in the same resources as the neighbor synchronization signal, the reception of the neighbor synchronization signal can be improved (e.g., by the WTRU receiving or attempting to receive the neighbor's synchronization signal). By avoiding transmission in channel resources used by other eNBs, interference from transmissions of other eNBs can also be avoided.

[0239] During active time for an LTE-U frequency band (e.g., a channel), an LTE-U eNB may not transmit (and / or may not expect to receive, such as from a WTRU) signals, such as data, control, and / or busy signals, on channel resources (e.g., a set of PRBs) that may be used by one or more other LTE-U eNBs to transmit one or more signals, such as an LTE-U synchronization signal. During active time, a WTRU that is capable of communicating with an eNB on the channel may not expect to receive (e.g., from an eNB) and / or may not transmit signals, such as data, control, and / or busy signals, on channel resources (e.g., a set of PRBs) that may be used by one or more other LTE-U eNBs to transmit one or more signals, such as an LTE-U synchronization signal. The eNB and / or WTRU may perform rate matching around one or more channel resources (e.g., a set of PRBs).

[0240] The eNB may receive and / or determine synchronization and / or busy signal information related to one or more other eNBs (e.g., neighbor eNBs). The eNB may determine the time and / or frequency location of one or more channel resources of synchronization and / or busy signals of one or more other eNBs (e.g., one or more neighbor eNBs managed by the same operator). For example, the eNB may determine the synchronization and / or busy signal of another eNB based on one or more of the following factors. The eNB may determine the synchronization and / or busy signal of another eNB based on receiving synchronization and / or busy signal information from the network. The eNB may determine the synchronization and / or busy signal of another eNB based on receiving synchronization and / or busy signal information over an X2 interface (e.g., from another eNB), as an example, the signal information may be actively provided or in response to a request for synchronization and / or busy signal information from the eNB. The eNB may determine the synchronization and / or blind signal of another eNB based on receiving, detecting, and / or decoding an over-the-air broadcast signal of another eNB. The eNB may determine the synchronization and / or busy signal of another eNB based on receiving synchronization and / or busy signal information from one or more connected WTRUs. As an example, the WTRU may determine synchronization and / or busy signal information of the eNB, for example, by receiving, detecting and / or decoding an over-the-air broadcast signal of the eNB. The over-the-air broadcast signal may include a synchronization and / or busy signal.

[0241] The eNB may perform rate matching on one or more DL signals (eg, all) at one or more determined time and / or frequency locations of its channel resources around synchronization and / or busy signals of one or more other eNBs.

[0242] The eNB may send a request for one or more time and / or frequency locations of one or more channel resources for synchronization and / or busy signals to another eNB. As an example, the request may be sent by the eNB over an X2 interface. The eNB may send the time and / or frequency locations of one or more channel resources for synchronization and / or busy signals to another eNB, for example, unsolicited or in response to a request from the other eNB. As an example, the time and / or frequency locations may be sent by the eNB over an X2 interface.

[0243] The eNB may send a request to the WTRU for the time and / or frequency location of one or more channel resources of a synchronization and / or busy signal of another eNB. As an example, the request may be sent by the eNB via higher layer signaling such as RRC signaling. The WTRU may send the time and / or frequency location of one or more channel resources of a synchronization and / or busy signal of a first eNB to a second eNB, for example, unsolicited or in response to a request from the second eNB. As an example, the information may be sent by the WTRU via higher layer signaling such as RRC signaling.

[0244] As an example, instead of and / or in addition to the sync and / or busy signals, one or more other signals and / or channels may be used.

[0245] An eNB rate matching and symbol mapping process may be provided. For example, the eNB may perform rate matching on a DL signal around one or more REs that may be used by a neighbor eNB, such as for synchronization and / or busy signals. In one example, during the rate matching process, the eNB does not map (e.g., any) data and / or control signal symbols to one or more REs around which rate matching is being performed on the DL signal, such as one or more REs that may be used by a neighbor eNB for its synchronization and / or busy signals. The eNB may skip one or more REs that may be used by a neighbor eNB for synchronization and / or busy signals during the symbol-to-RE mapping process. As an example, skipping one or more REs may be performed, such as by placing a modulation symbol mapped to the RE if it is not skipped in the next available RE, such as according to an RE mapping process or rule that may be fixed, preconfigured, known, or determined. One or more skipped REs may correspond to synchronization signal transmissions.

[0246] The eNB may map data and / or control signal symbols to one or more available REs that may be used for data and / or control signal mapping. The eNB may consider (e.g., any) RE that may overlap with a synchronization and / or busy signal of another eNB, such as a neighboring eNB, as an unavailable RE and / or may not use the RE in its symbol-to-RE mapping process. For example, the eNB may (e.g., may only) map blocks that may be coded, complex-valued data and / or control symbols to resource elements (e.g., REs within one or more PRB sets) that are not available for transmission of synchronization and / or busy signals of one or more other eNBs.

[0247] Different rate matching configurations (e.g., different arrangements of resources that may or should be available for the signal to be surrounded for rate matching) may affect the total number of useful REs for different subframes. The transport block size may depend on the rate matching configuration. For example, the transport block size (TBS) may be determined based on a combination of the MCS index and the applied rate matching configuration. In another example, the TBS may be independent of the rate matching configuration. The coding scheme may depend on the TBS and the rate matching configuration.

[0248] The WTRU reception may be based on the rate matching and / or symbol to RE mapping applied. The WTRU may determine which channel resources may and which channel resources may not carry complex-valued symbols (e.g., data and / or control symbols) intended to be received by the WTRU. As an example, this determination may be made as part of DL signal reception where rate matching may be performed around one or more channel resources (e.g., REs).

[0249] The WTRU may determine one or more channel resources (e.g., REs) that may be surrounded for rate matching (e.g., which may be performed by the eNB during a symbol-RE mapping process). As an example, the determination may be performed as part of receiving a DL signal transmission, where rate matching may be performed around one or more channel resources (e.g., REs) for the DL transmission. For example, the WTRU may demap one or more symbols of the DL transmission. One or more REs corresponding to synchronization signal transmissions may be skipped during the demapping process. The determination may enable the WTRU to demap one or more symbols, such as by reversing the mapping of symbols to REs by the eNB. The WTRU may demap symbols in accordance with the determination. As an example, during the demapping process, the WTRU may skip one or more REs that have been determined to be skipped or surrounded for rate matching, such as in a DL transmission. By skipping one or more REs when rate matching, the WTRU may detect and / or decode the transmitted data and / or control DL signals.

[0250] An indication of resources around which DL transmissions may be rate matched may be provided and / or used. The indication may be semi-static or dynamic.

[0251] As an example, the WTRU may determine one or more channel resources around which rate matching may be performed based on a configuration or information provided by the eNB via signaling, which may be, for example, physical layer or RRC signaling.

[0252] The WTRU may be configured with and / or informed by the eNB or network through or via the PCell of channel resources (e.g., a set of REs, PRBs, and / or subframes) that may be used to transmit LTE-U synchronization and / or busy signals of one or more other LTE-U eNBs. The WTRU may determine rate matching around the channel resources, for example, based on or according to the received configuration or information.

[0253] As an example, the configuration of channel resources that can be used by the eNB for synchronization and / or busy signals and / or the identification of the channel resources can be the same as the configuration of channel resources that can or should be used to perform rate matching and / or the identification of the channel resources.

[0254] For example, the WTRU may receive an indication from a (e.g., serving) eNB of one or more channel resources (e.g., REs for rate matching) that may or may have been used for a DL channel to surround to perform rate matching. The indication may include an indication of one or more channel resources of a synchronization and / or busy signal of another eNB.

[0255] The WTRU may be configured with and / or may receive an indication that may include one or more time and / or frequency resources (e.g., REs) for the eNB to perform rate matching on DL signal transmissions. The WTRU may be configured with and / or may receive an indication that may include information from which the WTRU may determine one or more time and / or frequency resources (e.g., REs) that may be used by the eNB to perform rate matching on DL signal transmissions. As an example, a configuration, such as a configuration related to rate matching, may be sent to the WTRU in higher layer signaling such as DCI and / or physical layer signaling.

[0256] The WTRU may receive an indication from an eNB indicating a set of channel resources around which the eNB may perform rate matching when transmitting a DL signal transmission. The set of channel resources may be periodic. As an example, a configuration may include one or more time locations, one or more frequency locations, and / or one or more transmission characteristics of a channel resource. A configuration may include one or more of the following: a period of a frame or subframe, a frame offset, such as a frame offset for a start frame, a subframe index or offset, and a time slot or time slot offset. A configuration may include one or more of the following: a subframe index within one or more radio frames, such as a time slot index within a subframe, a PRB and / or a PRB and / or a subcarrier that may be within a time slot, and / or one or more OFDM or SC-OFDM symbols that may be within these PRBs and / or subcarriers. As an example, when receiving and / or demapping a DL signal from an eNB, the WTRU may (or may understand or may be configured to) take into account rate matching around the indicated or determined time and / or frequency locations.

[0257] In one example, a WTRU may receive a subframe indication (e.g., from a serving eNB) for xx subframes, such as a 40-bit bitmap for xx=40 subframes. One (e.g., each) bit may indicate whether a corresponding subframe in a period of 40 subframes may contain a synchronization and / or busy signal that may be transmitted by another eNB. The WTRU may receive an indication of REs that may be used for synchronization and / or busy signals of other eNBs within a subframe such as the indicated one. As an example, when a subframe is indicated as likely to have another eNB transmitting a synchronization and / or busy signal, such as when a 40-bit subframe bitmap provides an indication, the WTRU may determine (e.g., by means of configuration) that a DL signal (e.g., from a serving eNB) may be rate matched around one or more of the configured and / or indicated REs in the subframe.

[0258] A WTRU may receive an indication in a DCI such as a DL grant that may identify or may be used by the WTRU to determine channel resources (e.g., PDSCH associated with a DL grant or later or other DL signals) that may be surrounded to perform rate matching on a DL signal. For example, a WTRU may receive a DCI in subframe n indicating rate matching around channel resources in subframe n+m. The value of m may be a fixed value and / or known to the WTRU. The value of m may be indicated to the WTRU in the same DCI, or may be configured through higher layer signaling. The indication may include a bitmap indicating resources that will not be used for symbol to RE mapping and / or demapping. The WTRU may be configured (e.g., in a semi-static manner) with a set of possible RE mapping configurations. As an example, a DCI such as a DL grant may include an indication (e.g., a code point) to indicate which of the configured mappings the WTRU may adopt or use in, for example, subframes n or n+m.

[0259] The WTRU may distinguish between two or more LTE-U synchronization signals from different eNBs, for example based on channel resources (e.g., REs, PRBs, and / or subframe sets) that may be allocated to or available for use by the two or more LTE-U synchronization signals.

[0260] One or more resources may be shared in different subframes. For example, a WTRU may be configured to have one or more channel resources (eg, REs or PRB sets) that may be in different subframes, where the channel resources may be used for different LTE-U synchronization signal transmissions.

[0261] As an example, a single PRB set may be allocated to one or more LTE-U synchronization signals in one or more subframes, all subframes, or a set of subframes. Two or more LTE-U eNBs may use the same PRB set for their LTE-U synchronization signal transmissions. However, each LTE-U eNB may perform transmissions in a different subset of subframes. For example, during the active time of the LTE-U band, the LTE-U eNB may transmit an LTE-U synchronization signal once every 4 subframes on the LTE-U band. The WTRU may expect an LTE-U synchronization signal from the LTE-U eNB in ​​a subframe where the two LSB SFN bits in the subframe may be equal to mod(PCell_cell_ID, 4) or mod(SCell_cell_ID, 4).

[0262] One or more resources may be shared with different PRB sets. A WTRU may be configured with one or more channel resources (eg, REs or PRB sets) that may be used by different LTE-U eNBs to perform LTE-U synchronization signal transmissions within the same subframe.

[0263] For example, assume that N PRB sets (e.g., four PRB sets) may be allocated for LTE-U synchronization signal transmission in one or more subframes, all subframes, or a set of subframes. It is possible that two or more LTE-U eNBs may transmit LTE-U synchronization signals in the same subframe. The two or more LTE-U eNBs may transmit LTE-U synchronization signals on different PRB sets. Among the configured PRB sets, the WTRU may expect the LTE-U synchronization signal from the LTE-U eNB in ​​the PRB set with index equal to mod(PCell_cell_ID, 4) or mod(SCell_cell_ID, 4).

[0264] Although the examples herein may be described in terms of PRB resources, the methods and techniques described herein may also be applicable to other types of resource usage. For example, other resources that may be used for LTE-U synchronization signal transmission, busy signal transmission, data transmission, etc. may be identified or defined by resource elements (REs), virtual resource blocks (VRBs), subcarriers, subframes, codes, other time-frequency resources, etc. Thus, the examples disclosed herein using PRBs as reference resources are also applicable to scenarios where resources are defined based on REs or other types of resource definitions (and vice versa).

[0265] The first eNB may map data and / or control signal symbols to one or more channel resources (e.g., REs) that may be used by the second eNB to transmit its synchronization and / or busy signal. The first eNB may mute one or more signal transmissions (e.g., perform signal muting) on ​​one or more (e.g., all) of these channel resources (e.g., REs) used by the second eNB.

[0266] As an example, muting transmissions on one or more channel resources (e.g., REs) may be performed by discarding (e.g., not transmitting or transmitting with zero power) one or more modulation symbols mapped to one or more channel resources (e.g., REs). One or more other REs of the same signal are not affected by the presence, location, and / or density of the muted REs.

[0267] The WTRU may determine and / or be explicitly and / or implicitly informed of the location of one or more silent channel resources (e.g., REs) in time and / or frequency. One or more methods described herein for configuring, notifying, or determining rate matching around channel resources may be applied to one or more silent channel resources.

[0268] For example, for a WTRU that has knowledge of quiet channel resources (e.g., REs) such as time and frequency locations, the WTRU may cause (e.g., force) received signal samples corresponding to these channel resources (e.g., REs) to be zero before using them for reception and / or decoding processing, e.g., before passing the signal samples to a receiver and / or decoding processing. By forcing one or more received signal samples, receiver performance may be improved, for example, by limiting input interference and / or noise levels when no meaningful information is being transmitted.

[0269] One or more LTE-U synchronization signals may be used in conjunction with resource overlap. The WTRU may receive two or more LTE-U synchronization signals from different LTE-U eNBs in the same set of PRBs and / or subframes. The two or more LTE-U synchronization signals may be configured taking into account orthogonal principles such as CDM, so that in the presence of LTE-U synchronization signals from other LTE-U eNBs that may cause interference, the WTRU may still detect its LTE-U synchronization signal. One or more techniques and / or design principles associated with CDM may be applicable. For example, different OCCs and / or scrambling may be applied for signals from different eNBs.

[0270] An indication of an LTE-U synchronization signal power offset may be provided. For example, the eNB may transmit an LTE-U synchronization signal having a certain power level. The power level may be different (e.g., a higher or lower power level) compared to other DL signals. The eNB may transmit a first LTE-U synchronization signal having a first power level and a second LTE-U synchronization signal having a second power level. A different (e.g., higher or lower) LTE-U synchronization signal transmission power compared to other DL signals (e.g., other synchronization signals, PDSCH, (E)PDCCH, PHICH) may improve synchronization, channel estimation, detection, and / or other mechanisms of the WTRU.

[0271] The power level of a signal such as a synchronization signal may correspond to the total power transmitted (and / or received) in a set of resources that are restricted in time and / or frequency. As an example, a set of resources that are restricted in time may include one or more resources indicated and / or included in a single (or a group or a certain number of) radio frames, subframes, time slots, OFDM symbols, etc. As an example, a set of resources that are restricted in frequency may include one or more resources indicated and / or included in a single (or a group or a certain number of) radio channels, PRBs, subcarriers, etc. A set of resources that are restricted in time and frequency may include a set of REs that carry signals such as synchronization signals. A set of resources that are restricted in time and frequency may include a set of OFDM and / or SC-FDMA symbols that constitute a specific number of PRBs.

[0272] As an example, the WTRU may determine the power level of the signal by detecting the signal and / or measuring its received power level.The WTRU may determine the power level of the signal based on power indications received from other entities in the network, such as from its eNB (eg, a serving eNB).

[0273] The WTRU may receive an indication of a power offset. The power offset may include a power offset (or potential power offset) between an LTE-U synchronization signal and one or more other DL signals. The eNB or network may provide an indication to the WTRU, which may be provided by or with the aid of a PCell that may be associated or aggregated with an LTE-U cell, for example. The indication may be provided to or received by the WTRU, which may be dynamic, such as via DL control signaling, or may be semi-static, such as via higher layer signaling, such as RRC signaling.

[0274] The WTRU may determine a power offset. The power offset may be between the synchronization signal transmission and one or more other downlink transmissions. The WTRU may determine a power level for a second downlink transmission based on the power offset.

[0275] The WTRU may determine the received power offset as the power level difference between two DL signal transmissions, such as first_dl_signal and second_dl_signal, where, as an example, first_dl_signal may be received by (or transmitted to) the WTRU before receiving (or transmitting) second_dl_signal.

[0276] The WTRU may determine a first_dl_signal for the indicated power offset. For example, the WTRU may determine that the first_dl_signal corresponding to the received power offset may be the last received synchronization signal before receiving the power offset indication. As another example, the WTRU may receive an indication of the subframe, signal type, and / or allocated resources of the first_dl_signal as part of the power offset indication.

[0277] The WTRU may determine a second_dl_signal for the indicated power offset. For example, after receiving the power offset indication, the WTRU may determine that the second_dl_signal corresponding to the received power offset contains a next received DL signal (e.g., PDSCH, (E)PDCCH). In another example, for example, as part of the power offset indication, the WTRU may receive an indication of the subframe, signal type, and / or allocated resources of the second_dl_signal.

[0278] For example, as part of a DL grant, the WTRU may receive an indication of a power offset (e.g., a power offset). As an example, the power offset may be interpreted as the amount by which the power of a data signal (or a control or reference signal) may be reduced compared to the power of an LTE-U synchronization signal. As an example, the power offset may be determined as the difference in power level (e.g., transmit power level per PRB) between corresponding signals such as first_dl_signal and second_dl_signal. The WTRU may determine (e.g., interpret) first_dl_signal as the last synchronization signal received before receiving the indication of the power offset. The WTRU may determine the synchronization signal power level by means of measurements. The WTRU may interpret second_dl_signal as the next PDSCH (or (E)PDCCH) signal. The WTRU may determine the power level of second_dl_signal (e.g., the next PDSCH) as the sum of the measured power level of first_dl_signal (e.g., the most recent synchronization signal) and the indicated power offset level. The sum may be scaled and / or adjusted by the number of resource blocks (e.g., PRBs) of first_dl_signal and second_dl_signal. The WTRU may use the indicated power offset, for example, using the power level of the LTE-U synchronization signal and / or the power level of the data (or control or reference) signal to determine the power of the other signal.

[0279] After receiving the power offset indication, the WTRU may interpret first_dl_signal as the next synchronization signal. The WTRU may measure the synchronization signal power level. The next synchronization signal may precede, overlap in time with, or be in the same subframe as second_dl_signal.

[0280] The WTRU may receive an indication of the power level of an LTE-U synchronization signal. The WTRU may receive an indication of the power level of one or more control and / or data signals.

[0281] The WTRU may perform frequency estimation, timing estimation, and / or synchronization (e.g., by using a synchronization signal). The WTRU may use the synchronization signal to perform channel estimation. The WTRU may use the synchronization signal to perform coherent demodulation and / or symbol scaling. For example, the WTRU may use the synchronization signal to perform channel estimation. The WTRU may use the estimated channel and / or the indicated power offset between the synchronization signal and the data / control signal (e.g., to appropriately scale the detected symbols before performing symbol demapping, before performing soft information calculation, before performing bit probability calculation, and / or before performing any other process before the channel decoding process).

[0282] The WTRU may perform frequency and / or timing estimation. The frequency and / or timing estimation may be based on synchronization signal transmission. The WTRU may perform demodulation and / or resource symbol scaling. The demodulation and / or resource symbol scaling may be based on synchronization signal transmission.

[0283] The use of LAA channels by different networks and / or operators may cause cell ID conflicts between cells (e.g., SCells) in the LAA channels. By determining the cell ID, cell ID conflicts can be avoided or reduced. For example, the cell ID of the LAASCell can be determined based on one or more of the following: an identifier of the eNB, such as a cell ID, a cell ID of the PCell of the eNB, the operator of the eNB, the center frequency of the licensed band used by the eNB, the center frequency of the unlicensed band used by the LAA SCell, or a random seed, etc.

[0284] The cell ID may be determined when the LAA SCell is deployed. The cell ID of the LAA SCell may be obtained when the LAA SCell is used, planned to be used, or deployed. The eNB may autonomously select the cell ID of the LAA SCell.

[0285] For a WTRU that can be served by an LAASCell, the WTRU can be informed of the timing of taking actions relative to the LAASCell via the PCell. As an example, the information that can be provided by the PCell may include the cell ID of the LAA SCell and / or the timing when such a cell ID can be applied to the LAA SCell or used by it. For example, the WTRU may be configured with an LAA SCell, and / or an indication of when actions such as synchronization, measurement, and / or PDSCH transmission will occur. One or more WTRU actions that can be taken for the LAASCell may be previously scheduled. The scheduling may be implicit or explicit. The WTRU may expect a signal from an LAASCell using a certain cell ID after (e.g., only after) receiving an indication of the cell ID and / or after the time applicable to the cell ID, where the time applicable to the cell ID may be provided or configured by the eNB via the PCell. As for synchronization or measurement, the WTRU may (e.g., only) use RS sampling at the valid time indicated by the PCell. If RS sampling is used at certain times indicated by the PCell, it will enable multiple LAASCells controlled by different eNBs in a single LAA channel to reuse the same cell ID. As an example, since signals transmitted by other LAASCells using the same cell ID as the WTRU's configured LAASCell will not occur at times that the WTRU considers valid, there will be no cell ID confusion at the WTRU.

[0286] The cell ID can be configured in a distributed manner. When the eNB can use, intends to use or deploys the LAA SCell, the eNB can select a cell ID. By selecting the cell ID, conflicts within the LAA channel can be avoided. For example, for an eNB that can configure the LAA SCell, the eNB may use the information exchange message described herein to communicate or negotiate with other eNBs so that the eNB can select a cell ID that has not been used, such as within a geographic area and / or on an LAA channel. Such communication or negotiation can be performed by broadcasting. For example, the eNB can broadcast the cell ID selected for the LAA SCell. The broadcast message can be located on an LAA channel (possibly the LAA channel on which the cell is operating) and / or an authorized spectrum. One or more other (e.g., neighboring) eNBs may respond, thereby possibly indicating whether there will be a conflict with one of the LAA SCells they have deployed.

[0287] Before using or deploying the LAA SCell, the eNB may perform listening on the LAA channel, for example, it may try to determine the cell ID of a cell that may be deployed on the LAA channel through a discovery process. The eNB may use another cell ID that does not conflict with the currently deployed LAA SCell. If the eNB can determine that the LAA SCell (or cell ID) will not be active on the LAA channel for a certain (e.g., pre-configured) amount of time, then the eNB may determine that the cell ID is no longer in use. The eNB may use the cell ID for the LAA SCell it uses or deploys.

[0288] The cell ID may be dynamically configured / indicated. For WTRU actions related to the LAA SCell, the PCell that may schedule such actions may indicate the cell ID to be used or assumed. Virtual cell IDs may be used. As an example, the LAA SCell may change the cell ID between active times. The WTRU may or may not know whether the new cell ID represents a cell that previously used the old cell ID. As an example, quasi-co-positioning between the old cell ID and the new cell ID may be provided to the WTRU or configured in the WTRU to enable faster synchronization. For example, measurements taken at a previous measurement opportunity may be used in conjunction with the current measurement. Cell ID (or virtual cell ID) hopping may be pre-configured and the WTRU may be aware of the cell ID (or virtual cell ID) hopping sequence and may operate correctly without being dynamically indicated a new (virtual) cell ID.

[0289] The LAA SCell may use channel hopping. For example, the eNB may deploy the LAA SCell on multiple channels. At a specific time, the LAA SCell may be active on (e.g., only on) a single channel. Except for the center frequency, the configuration of the LAA SCell may remain consistent. For example, the cell ID of the LAA SCell may remain constant regardless of the LAA channel at each active time. The cell ID of the LAA SCell may be based on time and / or LAA channel, and may change per active time. The WTRU may be aware of the relationship between the active time, the LAA channel, and the cell ID. The WTRU may or may not receive dynamic indications. The cell ID of the LAA SCell associated with the new active time may be indicated to the WTRU. The WTRU may use such information to determine the LAA channel on which the LAA SCell is active.

[0290] One or more eNBs use and / or operate in one or more LAA channels. For an eNB that can use and / or operate in an LAA channel, the eNB can be considered to have, use or operate an LAA cell, such as an LAASCell. An LAA cell or SCell belonging to one eNB can compete with another LAA cell or SCell belonging to another eNB for resources of the LAA channel. This competition can be in addition to or in place of competition with other users of the channel, such as WiFi users or radars.

[0291] As an example, multiple eNBs may share information and / or LAA channels to enable fair and / or efficient use of LAA channels between each other and other users. LAA channels may be shared and / or used by one or more eNBs, where the one or more eNBs may be associated with different operators. For example, LAA channels may be shared and / or used by one or more eNBs simultaneously in a TDM manner and / or an FDM manner.

[0292] In some examples, the terms communicate and negotiate are used interchangeably.

[0293] Parameters of the LAA cells may be communicated. The eNB may deploy or operate one or more LAA cells or SCells on the same or different unlicensed channels. The eNB may obtain a list of unlicensed channels for which it may monitor traffic. Such monitoring enables the eNB or one or more LAA cells or SCells to obtain one or more channels, such as channels for downlink transmissions.

[0294] The eNB may use or wish or intend to use the LAA channel. For example, the eNB may obtain or determine one or more LAA cell parameters through communication and / or negotiation (e.g., with another eNB that may or may also use or intend to use the channel). The one or more LAA cell parameters may be used by the eNB or other eNBs for a cell (e.g., LAASCell) associated with the channel.

[0295] LAA cell parameters may include one or more of the following: cell ID (e.g., cell ID of an LAA cell), synchronization signal configuration or information, reference signal configuration or information, busy signal configuration or information, and / or active time configuration or information.

[0296] The synchronization signal configuration or information may include information about resources available for use by the cell to transmit the synchronization signal.

[0297] The reference signal configuration or information may include information about reference signals (e.g., CRS, CSI-RS, CSI-IM, DM-RS, PRS) that can be transmitted in a cell, such as which reference signals can be transmitted in the cell, and / or information about resources available for use by the cell to transmit one or more (e.g., each) reference signals.

[0298] The busy signal configuration or information may include information about resources that may be used by the cell to transmit the busy signal.

[0299] Information related to resources used for transmission (e.g., transmission of synchronization signals, reference signals and / or busy signals) may include, but is not limited to, one or more of the following: RE mapping, subframe configuration and / or offset, orthogonal cover code (OCC), cyclic shift, random sequence generator parameters, one or more related PRBs, etc.

[0300] The active time configuration or information may include a timing or pattern (or multiple patterns), wherein the timing or pattern indicates a timing when a LAA cell (e.g., SCell) may become or attempt to become active or start, or a timing when an eNB turns on or attempts to turn on (put in an active state) a LAA cell (e.g., SCell). For an eNB. For example, an eNB that can monitor an LAA channel can determine or negotiate (with one or more other eNBs) a time instance (or timing) at which it can attempt to acquire a channel and can put a LAA cell (e.g., SCell) in an active state or start it.

[0301] An turned-on or active LAA cell may transmit one or more synchronization signals, may transmit one or more reference signals, may transmit one or more busy signals, and / or transmit DL data and / or control signals.

[0302] The eNB may determine or obtain information (e.g., live time configuration or information) regarding when another eNB may use or attempt to use the LAA channel. The eNB may not attempt to acquire the channel all or part of the time. As an example, this may save power by not attempting to acquire the channel when the channel is likely to be busy. This may reduce the probability of conflicting attempts to acquire the channel.

[0303] The WTRU may be configured with an LAA SCell. The configuration may be consistent with activating an SCell (e.g., an LAA SCell) on the WTRU. Parameters may be configured on the WTRU. These parameters enable the WTRU to be served by the LAA SCell. The parameters may include one or more LAA cell parameters. As an example, the value of the LAA cell parameter may be (or may have been) negotiated, obtained, or determined by the eNB based on communication or information exchange with another eNB. The value of the LAA cell parameter may or may not be the same value as the value provided to the WTRU (e.g., by the eNB) or configured in the WTRU. For example, the eNB may obtain or determine one or more resources for transmitting synchronization signals. The eNB may configure resources for the WTRU, wherein the resources may be the same as, different (or partially different), overlapping, or may be a subset of the certain resources.

[0304] The eNB may configure the WTRU with one or more quasi co-location (QCL) assumptions or sets of assumptions between, for example, the LAASCell and the PCell. The QCL assumptions may be for one or more of delay spread, average delay, Doppler spread, and Doppler shift. The WTRU may be configured with a set of multiple QCL assumptions, which may be configured dynamically or semi-statically, for example.

[0305] LAA cells can be revoked. For example, when the eNB will not (e.g., no longer) use or does not plan to use the LAA channel, the eNB can revoke the corresponding LAASCell. For example, when the eNB can stop monitoring a certain LAA channel, the eNB can revoke the SCell configured by the eNB to be used or work in a certain LAA channel.

[0306] Such revocation may mean that one or more (e.g., all) resources configured and / or reserved for the LAASCell may be released. The LAASCell or eNB may indicate to one or more LAASCells (e.g., neighboring LAASCells) that may use or operate on the affected LAA channel that it may release the LAASCell and / or one or more (e.g., all) of its resources.

[0307] The eNB may revoke the LAASCell from the LAA channel based on one or more of the following: channel congestion, traffic load, number of failed attempts to acquire the channel, number of eNBs or cells competing for the LAA channel, interference measurements, and / or one or more of the typical, average, or peak delays in the process of acquiring the channel. The one or more criteria may be measured or determined by the eNB and / or the WTRU. The one or more criteria measured or determined by the WTRU may be signaled to the eNB by the WTRU. If the one or more criteria exceed or fall below a certain threshold, the eNB may revoke the LAASCell.

[0308] The eNB can determine the number of competing deployments and / or active LAASCells that may be operating on the LAA channel. If the eNB determines that there is too much contention (e.g., too many other LAASCells in the channel), the eNB will not use the channel or may revoke the LAASCell from the channel.

[0309] For example, if the number of competing LAASCells in the same LAA channel is less than x, then the LAASCell may be deployed to operate on the LAA channel (e.g., operate only on it). When a first LAASCell (e.g., the eNB of the first LAASCell) determines that a new LAASCell has entered the LAA channel (e.g., has been deployed on the channel and / or is active on the channel) and / or the total number of competing LAASCells may (or may now) exceed a certain threshold, the first LAASCell may be revoked.

[0310] The first LAASCell (e.g., the eNB of the first LAASCell) can negotiate with the second LAASCell (e.g., the eNB of the second LAASCell) regarding resources (e.g., negotiating regarding the critical or high-importance use of the LAA channel). Based on the negotiation, one or more of the LAASCells or eNBs can determine that there are insufficient resources to meet the scheduling requirements and can withdraw the LAASCell from the LAA channel (e.g., a LAASCell without sufficient LAA channel resources).

[0311] As an example, an LAA cell may be configured or deployed with the intent to use the cell in the channel. One or more of the examples described in relation to revocation may be applied to a process for configuring or deploying a cell, where the decision making criteria for the process may be the same or opposite to the criteria described (e.g., exceeding a threshold may be replaced with being below a threshold, insufficient may be replaced with sufficient, etc.).

[0312] LAA channel information can be exchanged. For example, the eNB can share information related to its current or future use of one or more LAA channels. This information exchange can be used for resource negotiation or sharing between LAASCells described herein.

[0313] The information exchange between eNBs may be by means of an X2 or X2-like interface. The information exchange may be proactive (e.g., an eNB may transmit information to another (e.g., neighboring) eNB before a problem occurs due to the use of an LAA channel) or reactive (e.g., an eNB may transmit information to another (e.g., neighboring) eNB once a problem occurs due to the use of an LAA channel).

[0314] Information exchange between eNBs can be done by broadcast messages. Over-the-air broadcast of information can be used to transmit information such as the current or future use of one or more LAA channels by an eNB or LAA cell. Such messages can be unidirectional.

[0315] The broadcasted message may trigger neighboring cells affected by the contained information to respond to the broadcasted information, such response may be made through its own broadcast message or through any other means described herein.

[0316] The message may be broadcast from a PCell or a cell using licensed spectrum. The broadcast message may be associated with the use of one or more LAA channels. The broadcast message may originate from a LAASCell (or a cell using an unlicensed band). The information exchanged via the broadcast message may be associated with (e.g., only associated with) the LAASCell (or the LAA channel used by the LAASCell).

[0317] Broadcast messages may be included in the MIB and / or SIB. LAAMIB and / or SIB transmissions may be used to transmit these messages. For example, when the LAASCell has acquired a channel, the MIB and / or SIB may be transmitted in a resource subset. As an example, the MIB and / or SIB may be transmitted in certain subframes (e.g., a subframe subset or all subframes), and may be transmitted in one or more RBs or subcarriers, where the RB may be a group of center RBs or a subcarrier in a center RB.

[0318] MIB and / or SIB resources can be semi-statically assigned to LAASCells, and conflicts with LAASCells operating simultaneously can be limited. The MIB and / or SIB can be transmitted when the LAASCell is (or is not) active. The MIB and / or SIB can use repetition coding. For example, the message contained in the MIB and / or SIB can be repeated once every x subframes during the active time.

[0319] Resources may be reserved on each LAA channel. A LAASCell deployed on a channel may be assigned a set of such resources in order to broadcast information related to the current or future use of the LAA channel to neighboring LAASCells. For example, one or more symbols / time slots / subframes and subcarriers / PRBs / subbands may be reserved. The LAASCell may control such resources, for example by previously successfully acquiring a LAA channel or by negotiating semi-static ownership of such resources. The LAASCell may broadcast relevant information.

[0320] Broadcast messages may use LAASCell-specific reference signals that enable WTRU or other LAASCells to demodulate the message. For example, broadcast messages may be transmitted on one or more antenna ports, and / or demodulation may be performed using preconfigured precoding and / or CRS-like signals. As an example, scrambling and / or frequency hopping may be used on broadcast messages to reduce the impact of interference to nearby LAASCells and other RAT access points, as well as interference from the LAA SCells and access points.

[0321] The specific resources may be associated with the time when the LAASCell acquires or may acquire the LAA channel. The LAASCell may transmit broadcast messages in such resources. For example, the LAASCell may transmit the broadcast message in the xth symbol after acquiring the channel.

[0322] L1 signaling or channels can be used for information exchange. Information about the current or future use of LAA channels can be indicated by (or by using) one or more L1 signals or channels. Busy signals, one or more synchronization signals and / or reference signals, etc. can indicate relevant information. Parameters of signals and / or channels can indicate information related to the current or future use of LAA channels. For example, transmissions on a first group of REs can indicate a first information exchange message, transmissions on a second group of REs can indicate a second information exchange message, and transmissions on both groups of REs can indicate a third information exchange message. For signal parameters that can be used to indicate information related to the use of one or more LAA channels by LAASCell, the signal parameters may include but are not limited to: resources used in conjunction with subframes, (virtual) cell IDs that can be used to generate signal sequences, cyclic shifts of signals, orthogonal cover codes of signals, and / or antenna ports that can transmit signals. As an example, a specific signal can be indicated by an RB, symbol, or RE used to transmit a signal.

[0323] For example, a reference signal (RS) may be configured with a set of possible transmission resources (eg, RE mapping, PRB set, pseudo-random sequence, OCC, etc.), and the use of a specific set of resources for transmitting RS may signal relevant information to neighboring cells.

[0324] For example, for an RS that can be sent in a certain (e.g., last) subframe before the LAASCell releases the LAA channel and / or switches to an inactive state (or sleep), the RS can use one resource set. The same (or another) RS sent in another (e.g., any other) subframe will use another resource set. The eNB or cell can monitor the RS and / or can use the location of the RS of another (e.g., neighboring) LAA cell to determine that other LAA cells use or plan to release the channel.

[0325] The resources used by the RS in the last subframe in the active time can indicate whether the LAASCell remains deployed when it goes to sleep, or whether it will drop the LAA channel. The resources used for the synchronization signal sent when the LAASCell becomes active can indicate the length of time it remains active. The resources used to transmit a busy signal or a synchronization signal at the beginning of the active time can indicate the resources that can be reserved and / or used during the active time or a later active time. Doing so allows different LAASCells to use LAA concurrently or simultaneously.

[0326] L1 signals and / or channels can be used to exchange information related to the current or future use of LAA channels. Such information can be explicitly indicated in the channel / signal (e.g., by a coded information element in the channel / signal). Such information can be indicated in a manner similar to that described above for certain signals. The channel can be scheduled with the aid of (E)PDCCH, and it is possible to schedule it using a new DCI format. For example, channel parameters can be indicated in a DCI format that can be detected using RNTI. RNTI can be used by LAASCell on one or more LAA channels, or it can be dedicated to LAASCell. RNTI can be configured when LAASCell is deployed. The (E)PDCCH for message transmission on the scheduling channel can indicate information such as the following, but is not limited to: resources (e.g., RBs) used for message transmission on the new channel, message timing related to (E)PDCCH transmission, modulation and coding schemes, and / or demodulation reference signal parameters (e.g., antenna ports, orthogonal cover codes, cyclic shifts, quasi-coordinated position assumptions, precoders, and the transmit power ratio between demodulation reference signals and other reference signals). As an example, the timing of a message associated with a (E)PDCCH transmission may indicate that the message may be transmitted in the same subframe as the (E)PDCCH. The timing of a message associated with a (E)PDCCH transmission may indicate that the message may be transmitted in a subframe that may have been indicated or preconfigured after the (E)PDCCH is transmitted.

[0327] The channel may include a control region, wherein the control region indicates that parameters of the scheduled information exchange message may be indicated. The parameters included in the control region of the channel may be any parameters described herein for the (E)PDCCH. The LAASCell may pre-configure a portion of the channel (e.g., a set of RBs or REs) for control information.

[0328] The resources associated with the channel can be allocated based on the sub-TTI. For example, the channel can be transmitted in one of the two time slots in the TTI. The channel can be defined on a set of symbols within the time slot. The channel can be defined on a set of symbols spanning multiple time slots and / or subframes. The transmission power used for the channel can be different from the transmission power used for other channels. The control region of the channel can indicate the transmission power offset between the channel and perhaps one or more other signals and / or channels. The channel may include some REs dedicated to transmitting demodulation reference signals.

[0329] A LAASCell may transmit a beacon to convey information about its current or future use of an LAA channel. Such beacons may be transmitted at a preconfigured time. The beacon may be transmitted when the LAASCell is not in active mode. There may be a conflict between the beacon and other LAASCells (or other RATs) using the LAA channel. Such beacons may be transmitted on resources previously negotiated between deployed LAASCells that share the LAA channel. An LAASCell that is active when other LAASCells transmit their beacons may use a blank pattern on the resources used by the beacon. Doing so can limit the interference encountered by its WTRU.

[0330] For beacon transmissions performed by an active LAASCell or any other LAASCell, some resources of the LAA channel may be fixed. For example, a beacon may be transmitted by an active LAASCell at a preconfigured and possibly fixed or variable time instance (one or more OFDM symbols, one or more time slots, one or more subframes) and a subcarrier set. The beacon may include an indication of the LAASCell that transmitted it (e.g., a cell ID). Some resources may be reserved and used as beacons by other LAASCells that are currently deployed but dormant. In order to avoid conflicts between multiple dormant LAASCells, specific resources (e.g., RE or OCC) may be determined based on the cell ID of the LAASCell. Regardless of whether the LAASCell is active or dormant, the beacon may have resources determined based on the parameters of the LAASCell (e.g., cell ID).

[0331] Information may be exchanged via one or more WTRUs. The WTRU may act as an intermediary for information exchange between multiple eNBs. The eNB may configure the WTRU with a LAASCell, and through this configuration, the WTRU may be instructed to listen to possible information messages being transmitted by one or more LAASCells sharing the same LAA channel. The messages listened to by the WTRU may use any of the above methods for information exchange. For example, the WTRU may listen to neighboring LAASCell broadcast messages that provide information about the use of LAA channels. The WTRU may be provided with UL resources to report the information it collects from broadcast messages of one or more neighboring LAASCells, wherein the UL resources may be in the form of UL grants for its PCell.

[0332] The information collected by the WTRU can be passively transmitted by the neighboring LAASCell. Passive transmission of information means that the neighboring LAASCell does not actively try to exchange information with other LAASCells, but its current behavior in the LAA channel enables the WTRU or other LAASCells to make assumptions about their use of the LAA channel. For example, the WTRU can perform discovery and can measure the transmission of neighboring LAASCells. The WTRU can feed back the measurements. Based on the measurements, the WTRU's serving cell can use the LAA channel and / or the parameters of the configured LAA channel that normally use the LAA channel to determine the parameters of a specific LAASCell. For example, the WTRU may be configured with measurements about neighboring LAASCells. As an example, the WTRU may be given a threshold and may determine the amount of time that a neighboring LAASCell performs a transmission, where the amount of time will produce a measurement greater than the threshold. This enables the WTRU and, as an extension, the eNB to determine the activity level of the neighboring LAASCell.

[0333] The WTRU may be given information from its serving cell for sharing with other eNBs. For example, the WTRU may be provided with information about the current or future use of the LAASCell by its PCell. In addition, the WTRU may be given resources to try to connect to a neighboring cell (in a licensed band and / or an unlicensed band, if the unlicensed band allows UL transmission). Such resources may include a cell ID, physical random access channel (PRACH) parameters (preamble and resources), a timing reference, and may include a UL grant. The WTRU can enable information exchange by connecting to a neighboring cell in a licensed band. The serving cell may know the cell ID of the neighboring LAASCell in the LAA channel. The serving cell may or may not know the appropriate licensed cell operated by the same eNB. The serving cell determines the appropriate licensed cell based on the relationship between the cell ID of the LAASCell and its associated licensed band PCell. The WTRU may attempt to connect to one or more neighboring cells in order to transmit this information. The WTRU can use UL resources to transmit information for its serving cell (or one or more LAASCells of its serving eNB). Neighboring cells may determine whether any relevant information is being exchanged by listening to such resources.The WTRU's transmission may include an identifier of the LAASCell (or eNB) from which the information originates and / or an identifier of the LAASCell for which the information is intended.

[0334] The WTRU may start establishing a direct link between the serving eNB and the neighboring eNB by communicating with the neighboring eNB. For example, the WTRU may transmit relevant information (e.g., serving cell ID) to the neighboring cell, and the neighboring cell may establish an interface with the serving cell to exchange information.

[0335] Messages used to exchange information between two eNBs enable the effective use of one or more LAA channels. Here, the terms message and indication are used interchangeably and may refer to any information originating from an eNB (or a deployed LAASCell) and that can be used by another eNB (or another deployed LAASCell). This message or indication may include any information related to the current or future use of one or more LAA channels, and these contents will be further described here.

[0336] Messages may be transmitted periodically between eNBs. For example, when deploying the LAASCell, the eNB may begin periodically transmitting its LAA channel usage via one or more of the interfaces described herein. This periodic message transmission may be unidirectional. For example, the eNB does not expect any responses from neighboring eNBs. Periodic message transmissions may result in periodic or non-periodic responses from neighboring eNBs. As an example, the message may be non-periodic, such as a single message transmission. The eNB may transmit relevant information in the message and may or may not expect a response (e.g., an acknowledgement) from a neighboring eNB.

[0337] The information exchange message may (e.g., may always) be transmitted when the LAASCell is deployed (perhaps regardless of whether the LAASCell is active or dormant). The message may be transmitted only in one of the dormant state or active state. Different sets of resources or interfaces may be configured for information exchange in the active state and information exchange in the dormant state.

[0338] The message may be triggered by sending a message by the eNB. For example, the eNB may want to use the LAASCell to inform the neighboring eNB that it is currently using the LAA channel, and may transmit a message. The message may be prompted by another eNB. As an example, the first eNB may want to know the status of the second eNB (e.g., a channel monitoring set). The first eNB may send a trigger message that may prompt other eNBs to transmit a message indicating their status. The trigger message itself may be considered an information exchange message. The trigger message may result in a single transmission of a message reply, and / or may trigger periodic transmission of the message.

[0339] The message parameters may depend on the active or inactive (e.g., dormant) state of the LAASCell. For example, a dormant cell may transmit a message when prompted. An active cell may transmit a message periodically. The timing of periodic messages may be relative to the PCell and / or may be relative to the timing of the LAASCell. For example, a LAASCell that is asynchronous with the PCell (and whose timing in active time may depend on the time when the LAASCell acquires the LAA channel and becomes active) may transmit an information exchange message according to the time when the LAA channel is acquired.

[0340] The message can be used to convey information about the current or future use of one or more LAA channels. The message can be transmitted by means of an interface or mechanism as described herein. The message can originate from one or more of the following: an eNB with one or more LAASCells that have been deployed and are currently active in an LAA channel, an eNB with one or more LAASCells that have been deployed and are currently dormant in an LAA channel, an eNB that does not have an SCell with deployed LAA in one or more LAA channels, an LAA cell or SCell, a cell in a licensed spectrum such as a PCell, and the like.

[0341] For information contained in a message transmitted between two or more eNBs (or LAASCells), the information can enable fair and efficient use of one (or more) LAA channels. The information in the message can be used for unidirectional transmission. For example, the message can indicate that an eNB currently or will use an LAA channel. The information in the message can be used for bidirectional transmission. For example, the information can be able to implement negotiations between multiple eNBs, thereby achieving fair and efficient use of one or more LAA channels.

[0342] The information exchange message may include an identifier (e.g., a cell ID) of the source of the information exchange message. For example, the cell ID of an eNB cell or LAASCell in the licensed spectrum. The message may or may also include a list of deployed LAASCells that may be on multiple LAA channels. The list may include a recently revoked LAASCell (or a LAASCell that is about to be revoked). Doing so enables neighboring eNBs or LAASCells to track the traffic in the LAA channel.

[0343] The information exchange message may include an identifier (eg, a cell ID) of the intended destination of the message, such as a cell ID of a destination eNB cell in the licensed spectrum or a cell ID of one or more LAASCells.

[0344] The information exchange message may include a channel monitoring set. The eNB may indicate (e.g., to a neighboring eNB) its channel monitoring set. As an example, the message may include a list of channels that the eNB may be monitoring and / or may be trying to acquire. A monitored channel may be a channel with one or more deployed LAASCells. The channels included in the channel monitoring set may be one or more of the following: 1) not monitored, 2) monitored but no LAASCell is deployed, 3) monitored and LAASCell is deployed. The eNB may indicate changes to its channel monitoring set (e.g., some or all) in the message. For example, the message may include a complete list of monitored channels, or may (e.g., only) include updates to a previous set (which may take the form of channels to be added or removed from the channel monitoring set or changes in the monitoring type on each channel).

[0345] The information exchange message may include the timing of the current active time of the LAASCell. The information may indicate the start of the current active time, the end of the current active time, the length of the entire active time, and the remaining duration of the current active time. For some systems, such as synchronous systems, the timing information may refer to the PCell of the source eNB. For some systems, such as asynchronous systems, the message may (or may also) indicate the time reference (or an indication of another timing reference) at the time of information exchange. Doing so enables the destination eNB or LAASCell to understand the relative timing contained in the information exchange message.

[0346] The information exchange message may indicate the timing of the expected future activity time. This may include an indication of one or more of the expected activity time start, the expected activity time end, and the total expected activity time length.

[0347] The information exchange message may include an indication of the timing of deployment / deployment of the LAASCell. The source eNB may indicate when it will deploy or decommission one or more LAASCells.

[0348] The information exchange message may include an LAA channel access type. The message may indicate synchronous access (e.g., LAASCell may be synchronized to PCell) or asynchronous access (e.g., the timing of LAASCell may depend on the time when the LAA channel is available). The LAA channel access type may be decoupled from the message timing. The LAA channel access type may be indicated in the message. For example, the message transmission may be scheduled according to the timing synchronized with the PCell. Data transmission on the LAASCell may be asynchronous. LAASCell data transmission may use blank patterns on some REs (e.g., zero power transmission) to enable message transmission.

[0349] The information exchange message may include the LAASCell transmission power. The transmission power may be fixed for RBs and / or subframes within the active time. The transmission power may be changed on the subframes and / or RBs of the active time. Doing so can allow multiple LAASCells to use the LAA channel concurrently or simultaneously. The variable transmission power may be indicated by a transmission power pattern, where a subgroup (e.g., each) of the RBs and / or subframes of the active time may have an assigned value anywhere between 0 and the pre-configured maximum transmit power.

[0350] The information exchange message may indicate the interference level. The message may include an indication of the interference level in the LAA channel, such as the interference level encountered by the LAASCell and / or the WTRU served by the LAASCell. Such interference values ​​may be explicit. As an example, the interference level may be quantified and / or may be expressed as low, medium, and high. The interference level may represent the interference measured in the LAA channel and / or the interference acceptable to the LAASCell at the current or future active time source.

[0351] The information exchange message may include resource priority information or pattern. The source eNB may indicate different priority levels for resources used for its active time transmission and, where possible, for sleep time transmission. Such priority levels may be represented as patterns of different priorities for one or more of the RBs and / or symbols / time slots / subframes. The priority pattern may indicate how the eNB can and / or will prioritize use. Doing so enables adjacent LAASCells to use lower priority resources. The information exchange message and / or priority pattern may include or indicate a set of resources available for busy or synchronization signals. This information may be used to enable collaboration and / or joint transmission of busy signals performed by multiple LAASCells in an LAA channel.

[0352] The information exchange message may include an indication (or request) of high priority resources. For example, the eNB (or LAASCell) may indicate on the same or different LAA channels that it may or may request a priority for acquiring an LAA channel. For example, for an LAASCell, such as a dormant LAASCell, it may request or reserve the use of a channel for high priority purposes, such as transmitting a synchronization signal to the WTRU it serves so that the WTRU can maintain synchronization. The transmission of high priority resources (as an example, or a request for the resources) triggers a fallback operation on another (e.g., adjacent) LAASCell, such as enabling the LAASCell to transmit a high priority indication indicating a higher possibility of acquiring an LAA channel.

[0353] The information exchange message may include an indication of radar activity detection. An eNB (or LAASCell) may indicate to another eNB (or LAASCell) that a radar has been detected on the LAA channel. Doing so may cause the neighboring eNB to stop attempting to acquire the LAA channel and / or may cause the eNB to revoke the LAASCell on the LAA channel.

[0354] The information exchange message may indicate long-term behavior. This may indicate to the recipient of the message that such an LAA channel is expected to use the source LAASCell for a longer period of time. For example, the source LAASCell may indicate the amount or type of traffic expected by the WTRU served by the LAASCell. As an example, the source LAASCell may indicate whether the traffic is expected to last for multiple active times and / or how many active times it lasts. The message may include the rate at which the LAASCell will attempt to acquire the LAA channel in the future. The amount of traffic may be indicated in a report similar to or through a buffer status report. The message may include the number of WTRUs that can be served by the LAASCell.

[0355] The content of the message may be explicitly included in the message, or may be implicitly included (e.g., determined based on one or more parameters or characteristics of the message or message transmission). For example, a parameter or characteristic of an information exchange message (e.g., the resources used to transmit the message, such as a subframe and / or PRB) may implicitly indicate one or more possible contents of the message as described herein (e.g., the remaining duration of the active time).

[0356] LAA channel resources can be shared between eNBs. eNBs can use information exchange messages to share LAA channels.

[0357] The first eNB may deploy a first LAASCell. For example, the eNB or LAASCell may use one or more of the solutions described herein to indicate that it may be (or may become) active and / or may be active for a specific duration x (the duration may be measured in symbols, time slots, subframes, etc.). The second eNB or LAASCell may share one or more channels by negotiation with the first eNB / LAASCell. For example, the second eNB (or second LAASCell) may indicate one or more of the following to the first eNB (or LAASCell) via an information exchange message: a desire or request to use or share multiple RBs or a set of RBs, and / or an expected or requested amount of time for RBs, wherein the amount of time may be less than the remaining activity time of the first LAASCell.

[0358] The first LAASCell may agree to the request and, as an example, may not stop or may stop scheduling on the RBs indicated by the second LAASCell for the requested amount of time. The first LAASCell may indicate to the second LAASCell a set of resources (RBs and / or subframes) or another set of resources on which the first LAASCell does not transmit and / or the second LAASCell transmits.

[0359] For a set of RBs that a second LAASCell may desire or request and / or that a first LAASCell may release to enable the second LAASCell to send data, the set may include part or all of the bandwidth of the LAA channel. During the time (e.g., a subset of subframes) that the second LAASCell may have the channel, the first LAASCell may remain active but may not perform transmissions.

[0360] The second LAASCell may request (and / or the first LAASCell may provide) a set of RBs in which the first LAASCell may reduce its transmission power so that the second LAASCell can perform simultaneous transmissions on the same RBs.

[0361] As an example, the second eNB (or second LAASCell) may indicate to the first eNB (or LAASCell) its willingness or request to acquire a LAA (eg, full LAA) channel before the end of the previously indicated activity time of the first LAASCell via an information exchange message.

[0362] If the first LAASCell agrees, it can return to an inactive (or dormant) state before its originally indicated or expected time. The first LAASCell can collaborate with the second LAASCell to ensure that the channel remains (or appears to remain) busy during the switching time when the second LAASCell can acquire the channel. Doing so can prevent other cells or access points from acquiring the channel before the second LAASCell begins its transmission. As long as the cell is allowed to maintain a channel (for example, before this), the second LAASCell can maintain the channel (for example, until), regardless of how long the first LAASCell has the channel. As long as the first LAASCell remains in its active period, the second LAASCell can maintain the channel. The remaining time may depend on an indication sent by the first LAASCell, or may depend on the maximum active period for LAA channel acquisition permitted by regulation.

[0363] As an example, the second eNB (or second LAASCell) may indicate to the first eNB (or LAASCell) a request for an interference report from a WTRU connected to the first LAASCell via an information exchange message. As an example, the first LAASCell may trigger an interference measurement report from its WTRU to determine whether the second LAASCell can perform simultaneous transmissions without significantly degrading the WTRU performance of the first LAASCell. The measurement resources available to the WTRU may be negotiated between the first and second LAASCells. As an example, the second LAASCell may transmit a pseudo-interference signal to enable the WTRU of the first LAASCell to measure (e.g., appropriately) the impact of potential transmissions from the second LAASCell.

[0364] An interference request from the second LAASCell may cause the first LAASCell to reply with an interference indication. For example, the first LAASCell may indicate one of two interference levels: low (as an example, this means that the second LAASCell may perform simultaneous transmissions) or high (as an example, this means that the second LAASCell should not perform simultaneous transmissions). More than two interference levels may be used for the indication. The first LAASCell may indicate to the second LAASCell a set of precoding matrices that may or may not be used, for example, to limit the interference that the WTRU of the first LAASCell may encounter.

[0365] As an example, the second eNB (or second LAASCell) may indicate to the first eNB (or LAASCell) a set of interference measurements that may be taken by the WTRU of the second LAASCell via an information exchange message. As an example, this may enable the first LAASCell to modify its transmission power or precoding to limit the interference that the WTRU of the second LAASCell may encounter. As an example, the second LAASCell may provide a list of favorable (or unfavorable) precoding matrices that may be used (or not used) by the first LAASCell to limit interference to the WTRU of the second LAASCell.

[0366] As an example, the second eNB (or second LAASCell) may indicate to the first eNB (or LAASCell) a request for the first LAASCell to transmit a signal (e.g., a busy signal) via an information exchange message. This may indicate to the second LAASCell when (e.g., an exact or nearly exact moment) the first LAASCell will abandon the channel. This enables the second LAASCell to have priority access to the channel before other LAASCells or other RATs. This processing may (e.g., may only) be applied to or used to transmit high priority signals (e.g., reference signal transmissions that enable the WTRU to synchronize with the LAASCell). The LAASCell may (or may only) acquire (or be allowed to acquire) a channel in a manner that is used for certain transmissions, such as high priority transmissions, and may limit the length of time that it remains active after transmitting a high priority signal.

[0367] As an example, the second eNB (or second LAASCell) may indicate to the first eNB (or LAASCell) a request to jointly send a busy (or synchronization) signal through the first and second LAASCells by means of an information exchange message. The transmission of such signals can be completed in the same resources, and thereby the power of other nodes to receive the signal may be increased, or the coverage of the signal may be improved. The transmission of such signals may be performed on orthogonal resources. For example, the first LAASCell may send a busy signal in the first group of subcarriers of a symbol. The second LAASCell may send a busy signal in the second group of subcarriers of the same symbol.

[0368] As an example, the second eNB (or second LAASCell) may indicate to the first eNB (or LAASCell) via an information exchange message a request for the first LAASCell to transmit a synchronization signal that enables the second LAASCell to synchronize. In response to the request, the first LAASCell may transmit a synchronization signal. Doing so enables the two LAASCells to share resources during the same active time and can be used when the LAASCell is not synchronized with its corresponding PCell.

[0369] As an example, the second eNB (or second LAASCell) can indicate to the first eNB (or LAASCell) the channel that the second LAASCell will select in the upcoming active time by means of an information exchange message. The second LAASCell can request the first LAASCell to indicate the channel it can use in the next active time. These solutions enable the two LAASCells to coordinate their work when using dynamic frequency selection. Two or more LAASCells can reduce the possibility of trying to acquire the same channel through negotiation. The LAASCell can use dynamic frequency selection. The LAASCell can indicate to another (e.g., neighboring) LAASCell the frequency hopping pattern it may use. The LAASCells can share resources in the overlapping portion of the channel through negotiation.

[0370] For example, the first eNB or the first LAASCell can indicate to the second eNB or the second LAASCell that it has acquired the LAA channel. The indication can be sent in the form of a preamble. This indication enables multiple LAASCells to share the active time of the first LAASCell at the same time, for example, using the same resources. The preamble can indicate one or more timings of the LAASCell (so that other LAASCells can synchronize to the cell that initially acquired the channel), the timing / length of the active time (so that other LAASCells know how long they can remain active), the LAASCell (virtual) cell ID, the transmission power of the LAASCell, and / or the busy and / or synchronization signal configuration of the LAASCell.

[0371] The methods and means described herein may be applied to other wireless technologies and other services, either alone or in any combination.

[0372] The WTRU may refer to the identity of the physical device, or to the identity of the user, such as a subscription-related identity, such as MSISDN, SIP URI, etc. The WTRU may refer to an application-based identity, such as a username used by the application.

[0373] The above process may be implemented in a computer program, software and / or firmware that is incorporated into a computer-readable medium for execution by a computer and / or processor. Examples of computer-readable media include, but are not limited to, electrical signals (transmitted via a wired or wireless connection) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, read-only memory (ROM), random access memory (RAM), registers, buffer memory, semiconductor storage devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). A processor associated with the software may be used to implement a radio frequency transceiver used in a WTRU, UE, terminal, base station, RNC, and / or any host computer.

Claims

1. A wireless transmit / receive unit (WTRU), the WTRU comprising: A processor configured to: monitoring a first indication that a base station associated with the WTRU has acquired a channel; receiving the first indication from the base station via a physical downlink control channel (PDCCH) message, wherein the PDCCH message is associated with a specific radio network temporary identifier and wherein the first indication is used to indicate a time period during which the channel is occupied by the base station; receiving a second indication from the base station regarding a grant, wherein the grant provides the WTRU resources for performing transmission within the time period indicated by the first indication; as well as The transmission to the base station is performed during the time period indicated by the first indication, wherein the transmission is performed using the received grant.

2. The WTRU of claim 1 , wherein the processor is configured to: receiving a configuration indicating one or more of a time or a frequency associated with the monitoring of the first indication; and Based on the configuration, the first indication is monitored.

3. The WTRU of claim 1 , wherein the received grant is an uplink grant received following a downlink transmission from the base station.

4. The WTRU of claim 1 , wherein the PDCCH message further indicates available resource blocks (RBs) for performing the transmission during the time period indicated by the PDCCH message.

5. The WTRU of claim 1 , wherein the channel acquired by the base station is an unlicensed channel.

6. A method comprising: monitoring a first indication indicating that the base station has acquired a channel; receiving the first indication from the base station via a physical downlink control channel (PDCCH) message, wherein the PDCCH message is associated with a specific radio network temporary identifier and wherein the first indication is used to indicate a time period during which the channel is occupied by the base station; receiving a second indication from the base station regarding a grant, wherein the grant provides resources for the WTRU to perform a transmission during the time period indicated by the first indication; as well as The transmission to the base station is performed during the time period indicated by the first indication, wherein the transmission is performed using the received grant.

7. The method according to claim 6, wherein the method further comprises: receiving a configuration indicating one or more of a time or a frequency associated with the monitoring of the first indication, Wherein the monitoring of the first indication is performed based on the configuration.

8. The method of claim 6, wherein the grant is an uplink grant received by the WTRU following a downlink transmission from the base station.

9. The method of claim 6, wherein the PDCCH message further indicates available resource blocks (RBs) for performing the transmission within the time period indicated by the PDCCH message.

10. The method of claim 6, wherein the channel acquired by the base station is an unlicensed channel.

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