WTRU, method performed by WTRU, and base station

Abstract

Disclosed are systems and methods for determining a first downlink control indicator (DCI) and a second DCI, determining an active aperiodic channel state information reference signal (A-CSI-RS) set based on the first DCI, and determining a subset of the active A-CSI-RS set based on the second DCI. A WTRU may perform resource element (RE) muting based on the active A-CSI-RS set. A WTRU may perform channel state information (CSI) measurements based on the subset of the active A-CSI-RS set.

Description

[0001] This application is a divisional application of Chinese invention patent application No. 201780061478.7, entitled “System and method for non-periodic measurement reference signal transmission in a multi-antenna system”, filed on August 10, 2017, which is incorporated herein by reference in its entirety.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Provisional Patent Application No. 62 / 373,248, filed on August 10, 2016, entitled “System and Method for Periodic Measurement Reference Signal Transmission in a Multi-Antenna System,” which is incorporated herein by reference in its entirety. Background Art

[0004] Channel State Information Reference Signals (CSI-RS) can be used for measurement purposes in Long Term Evolution (LTE) wireless communication systems. One or more CSI-RS patterns can be a function of the number of antenna ports that can be used by the device generating such patterns. Such patterns can be provided in a transmission subframe. Summary of the Invention

[0005] This summary introduces a series of concepts in a simplified form, which are further described in the detailed description below. This summary is not intended to identify key features and / or essential features of the claimed subject matter, nor should it be construed as limiting the scope of the claimed subject matter.

[0006] Disclosed are systems and methods for determining a first downlink control indicator (DCI) and a second DCI, determining an active aperiodic channel state information reference signal (A-CSI-RS) set based on the first DCI, and determining a subset of the active A-CSI-RS set based on the second DCI. Resource element (RE) muting may be performed based on the active A-CSI-RS set. Channel state information (CSI) measurements may be performed based on the subset of the active A-CSI-RS set. RE muting as disclosed herein may be puncturing or rate matching of REs surrounding the active A-CSI-RS set in order to receive a physical downlink shared channel (PDSCH) transmission. Further disclosed are systems and methods for determining at least one A-CSI-RS pattern based on the subset of the active A-CSI-RS set, wherein the at least one A-CSI-RS pattern may be associated with a WTRU.

[0007] Disclosed are systems and methods for performing CSI measurements based on a subset of an active A-CSI-RS set by performing CSI measurements based on at least one A-CSI-RS pattern. Performing RE muting based on the active A-CSI-RS set may include muting at least one downlink transmission. A physical downlink control channel (PDCCH) common search space (CSS) may be monitored to detect DCI that may be received via the PDCCH CSS. An enhanced physical downlink control channel (EPDCCH) common search space (CSS) may be monitored to detect DCI that may be received via the EPDCCH CSS.

[0008] Disclosed are systems and methods for monitoring a WTRU-specific search space and determining DCI based on the WTRU-specific search space. Determining a flag bit based on the DCI may be performed, wherein the flag bit may indicate whether the DCI includes a subset of the active A-CSI-RS set. RE muting may be performed based on at least one of time or frequency location. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The following detailed description of exemplary embodiments is provided with reference to the accompanying drawings. For illustrative purposes, the accompanying drawings show exemplary embodiments. The intended subject matter is not limited to the specific elements and / or instrumentalities described or illustrated. No subject matter is to be considered essential and / or necessary unless specifically indicated to the contrary. In addition, the described embodiments may be used in whole or in part in any combination. In the drawings:

[0010] Figure 1A is a system diagram of an exemplary communication system in which one or more disclosed embodiments may be implemented.

[0011] Figure 1B This is to illustrate that according to the embodiment Figure 1A A system diagram of an exemplary wireless transmit / receive unit (WTRU) for use within the communication system described in FIG.

[0012] Figure 1C It is shown that according to the embodiment, Figure 1A A system diagram of an exemplary radio access network (RAN) and an exemplary core network (CN) for use within the illustrated communication system.

[0013] Figure 1D It is shown that according to the embodiment, Figure 1A A system diagram of another exemplary RAN and another exemplary CN used within the illustrated communication system.

[0014] Figure 2 is a diagram illustrating an exemplary reference signal according to an embodiment.

[0015] Figure 3 is a diagram illustrating an exemplary enhanced resource element group (EREG) according to an embodiment.

[0016] Figure 4 is a diagram illustrating exemplary resource elements (REs) according to an embodiment.

[0017] Figure 5 is a diagram showing an exemplary reference signal (RS) configuration according to an embodiment. DETAILED DESCRIPTION

[0018] A detailed description of exemplary embodiments will now be described with reference to the accompanying drawings. Although this description provides detailed examples of possible implementations, it should be noted that the details are intended to be exemplary and in no way limit the scope of the present application. As used herein, the articles "a" or "an" without further qualification or characterization may be understood to mean, for example, "one or more" or "at least one." Furthermore, as used herein, the phrase "user equipment" (UE) may be understood to mean the same thing as the phrase "wireless transmit / receive unit" (WTRU).

[0019] Figure 1A is a diagram illustrating an exemplary 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 may enable multiple wireless users to access such content by sharing system resources, including wireless bandwidth. For example, the communication system 100 may employ one or more channel access methods, such as code division multiple access (CDMA), time division multiple access (TDMA), frequency division multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrier FDMA (SC-FDMA), zero-tailing unique word DFT-Spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block filtered OFDM, filter bank multi-carrier (FBMC), etc.

[0020] like Figure 1AAs shown, the communication system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RAN 104 / 113, CN 106 / 115, public switched telephone network (PSTN) 108, the Internet 110, and other networks 112. However, it will be appreciated that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of the WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. By way of example, the WTRUs 102a, 102b, 102c, 102d (any of which may be referred to as a base station and / or a “STA”) 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 subscription-based unit, a pager, a cellular phone, a personal digital assistant (PDA), a smartphone, a laptop, a netbook, a personal computer, a wireless sensor, a hotspot or Mi-Fi device, an Internet of Things (IoT) device, a watch or other wearable device, a head-mounted display (HMD), a vehicle, a drone, medical equipment and applications (e.g., remote surgery), industrial equipment and applications (e.g., robots and / or other wireless devices operating in an industrial and / or automated process chain environment), a consumer electronic device, a device operating on a commercial and / or industrial wireless network, etc. Any of the WTRUs 102a, 102b, 102c, 102d may be interchangeably referred to as a UE.

[0021] The communication system 100 may also include a base station 114a and / or a base station 114b. Each of the base stations 114a, 114b may be any type of device configured to wirelessly interface with at least one of the WTRUs 102a, 102b, 102c, 102d to facilitate access to one or more communication networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. By way of example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node B, an eNode B, a Home Node B, a Home eNode B, a gNB, an NR Node B, a site controller, an access point (AP), a wireless router, and the like. While the base stations 114a, 114b are each depicted as a single element, it will be appreciated that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0022] Base station 114a may be part of RAN 104 / 113, which may also include other base stations and / or network elements (not shown), such as a base station controller (BSC), a radio network controller (RNC), repeaters, etc. Base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, which may be referred to as cells (not shown). These frequencies may be licensed spectrum, unlicensed spectrum, or a combination of licensed and unlicensed spectrum. A cell may provide wireless service coverage for a specific geographic area, which may be relatively fixed or may change over time. A cell may be further divided into cell sectors. For example, the cell associated with base station 114a may be divided into three sectors. Thus, in one example, base station 114a may include three transceivers, one for each cell sector. In one example, base station 114a may employ multiple-input multiple-output (MIMO) technology and may use multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in a desired spatial direction.

[0023] The base stations 114a, 114b may communicate with one or more of the WTRUs 102a, 102b, 102c, 102d over an air interface 116, which may be any suitable wireless communication link (e.g., radio frequency (RF), microwave, centimeter wave, micrometer wave, infrared (IR), ultraviolet (UV), visible light, etc.). The air interface 116 may be established using any suitable radio access technology (RAT).

[0024] More specifically, as described above, the communication system 100 may be a multiple access system and may employ one or more channel access schemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. For example, the base station 114a in the RAN 104 / 113 and the WTRUs 102a, 102b, 102c may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may 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 (DL) Packet Access (HSDPA) and / or High Speed ​​UL Packet Access (HSUPA).

[0025] In one example, 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 116 using Long Term Evolution (LTE) and / or LTE-Advanced (LTE-A) and / or LTE-Advanced Pro (LTE-A Pro).

[0026] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as NR radio access, which may establish the air interface 116 using New Radio (NR).

[0027] In one embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may jointly implement LTE radio access and NR radio access, e.g., using dual connectivity (DC) principles. Thus, the air interface used by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0028] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology such as IEEE 802.11 (i.e., Wireless Fidelity (WiFi)), IEEE 802.16 (i.e., Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000, CDMA2000 1X, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), Interim Standard 856 (IS-856), Global System for Mobile communications (GSM), Enhanced Data rates for GSM Evolution (EDGE), GSM Evolution (GERAN), etc.

[0029] For example, Figure 1AThe base station 114b in the example may be a wireless router, a Home NodeB, a Home eNodeB, or an access point, and may utilize any suitable RAT to facilitate wireless connectivity in a local area, such as a business, a home, a vehicle, a campus, an industrial facility, an air corridor (e.g., for use by drones), a road, and the like. In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.11 to establish a wireless local area network (WLAN). In one embodiment, the base station 114b and the WTRUs 102c, 102d may implement a radio technology such as IEEE 802.15 to establish a wireless personal area network (WPAN). In yet another embodiment, the base station 114b and the WTRUs 102c, 102d may utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE, LTE-A, LTE-A Pro, NR, etc.) to establish a picocell or femtocell. Figure 1A As shown, base station 114b may have a direct connection to Internet 110. Thus, base station 114b may not be required to access Internet 110 via CN 106 / 115.

[0030] The RAN 104 / 113 may be in communication with the CN 106 / 115, 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. Data may have different quality of service (QoS) requirements, such as different throughput requirements, latency requirements, fault tolerance requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 may provide call control, billing services, mobile location-based services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform advanced security functions, such as user authentication. Although not described in Figure 1A Although not shown in the figures, it will be appreciated that the RAN 104 / 113 and / or the CN 106 / 115 may be in direct or indirect communication with other RANs that employ the same RAT as the RAN 104 / 113 or a different RAT. For example, in addition to being connected to the RAN 104 / 113, which may utilize NR radio technology, the CN 106 / 115 may also be in communication with another RAN (not shown) that employs GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0031] The CN 106 / 115 may also serve as a gateway for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network that provides plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols, such as the Transmission Control Protocol (TCP), User Datagram Protocol (UDP), and / or Internet Protocol (IP) from the TCP / IP internet protocol suite. The networks 112 may include wired and / or wireless communication networks owned and / or operated by other service providers. For example, the networks 112 may include another CN connected to one or more RANs, which may use the same RAT as the RAN 104 / 113 or a different RAT.

[0032] 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 via 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.

[0033] Figure 1B is a system diagram illustrating an exemplary WTRU 102. Figure 1B As shown, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power supply 134, a global positioning system (GPS) chipset 136, and / or other peripherals 138. It will be appreciated that the WTRU 102 may include any subcombination of the foregoing elements while remaining consistent with an embodiment.

[0034] The processor 118 may be a general purpose processor, a special purpose processor, a conventional processor, a digital signal processor (DSP), a plurality of microprocessors, one or more microprocessors associated with a DSP core, a controller, a microcontroller, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) circuit, any other type of integrated circuit (IC), a state machine, etc. The processor 118 may perform signal coding, data processing, power control, input / output processing, and / or any other functionality that enables the WTRU 102 to operate in a wireless environment. The processor 118 may be coupled to the transceiver 120, which may be coupled to the transmit / receive element 122. Although Figure 1B The processor 118 and the transceiver 120 are depicted as separate components, but it is understood that the processor 118 and the transceiver 120 may be integrated together in an electronic package or chip.

[0035] The transmit / receive element 122 can be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) via the air interface 116. For example, in one embodiment, the transmit / receive element 122 can be an antenna configured to transmit and / or receive RF signals. In one example, the transmit / receive element 122 can be an emitter / detector configured to, for example, transmit and / or receive IR, UV, or visible light signals. In yet another embodiment, the transmit / receive element 122 can be configured to transmit and / or receive RF and light signals. It should be understood that the transmit / receive element 122 can be configured to transmit and / or receive any combination of wireless signals.

[0036] Although the transmit / receive element 122 is Figure 1B Although depicted as a single element in FIG. 1 , the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO technology. Thus, in one embodiment, the WTRU 102 may include two or more transmit / receive elements 122 (e.g., multiple antennas) for transmitting and receiving wireless signals over the air interface 116.

[0037] The transceiver 120 may be configured to modulate signals to be transmitted by the transmit / receive element 122 and 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 to enable the WTRU 102 to communicate via multiple RATs, such as NR and IEEE 802.11.

[0038] The processor 118 of the WTRU 102 may be connected to and receive user input data from the speaker / microphone 124, the keypad 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). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. In addition, the processor 118 may access information from and store data in any suitable type of memory, such as non-removable memory 130 and / or removable memory 132. The non-removable memory 130 may include random access memory (RAM), read-only memory (ROM), a hard disk, or any other type of memory device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, or the like. In other embodiments, the processor 118 may access information from and store data in memory that is not physically located on the WTRU 102, such as on a server or a home computer (not shown).

[0039] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control power to the other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. By way of example, the power source 134 may include one or more dry cell batteries (e.g., a nickel-cadmium (NiCd) battery, a nickel-zinc (NiZn) battery, a nickel-metal hydride (NiMH) battery, a lithium-ion (Li-ion) battery, etc.), solar cells, fuel cells, etc.

[0040] The processor 118 may also be connected 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, 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 using any suitable location-determination method while remaining consistent with an embodiment.

[0041] The processor 118 may further be connected to other peripheral devices 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripheral devices 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or video), a universal serial bus (USB) port, a vibration device, a television transceiver, a hands-free headset, module, a frequency modulation (FM) radio unit, a digital music player, a media player, a video game player module, an Internet browser, a virtual reality and / or augmented reality (VR / AR) device, an activity tracker, etc. The peripheral device 138 may include one or more sensors, which may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, an orientation sensor, a proximity sensor, a temperature sensor, a time sensor, a geolocation sensor, an altimeter, a light sensor, a touch sensor, a magnetometer, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0042] The WTRU 102 may include a full-duplex radio for which the transmission and reception of some or all signals (e.g., associated with particular subframes used for uplink (e.g., for transmission) and downlink (e.g., for reception)) may be concurrent and / or simultaneous. The full-duplex radio may include an interference management unit 139 to reduce and / or substantially eliminate self-interference through hardware (e.g., chokes) or signal processing via a processor (e.g., a separate processor (not shown) or through the processor 118). In one embodiment, the WTRU 102 may include a half-duplex radio for which the transmission and reception of some or all signals (e.g., associated with particular subframes used for uplink (e.g., for transmission) or downlink (e.g., for reception)) may be concurrent and / or simultaneous.

[0043] Figure 1C 1 is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. 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. The RAN 104 may also be in communication with the CN 106.

[0044] The RAN 104 may include eNode-Bs 160a, 160b, 160c, though it will be appreciated that the RAN 104 may include any number of eNode-Bs while remaining consistent with an embodiment. The eNode-Bs 160a, 160b, 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0045] Each of the eNodeBs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, etc. Figure 1C As shown, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0046] Figure 1C The CN 106 shown in FIG. 1 may include a mobility management entity (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (or PGW) 166. While each of the foregoing elements is depicted as being part of the CN 106, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0047] The MME 162 may be connected to each of the eNode-Bs 162a, 162b, 162c in the RAN 104 via an S1 interface and may 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 for switching between the RAN 104 and other RANs (not shown) that employ other radio technologies, such as GSM and / or WCDMA.

[0048] The SGW 164 may be connected to each eNode-B 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to and from the WTRUs 102a, 102b, 102c. The SGW 164 may 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.

[0049] The SGW 164 may be connected to the PGW 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.

[0050] The CN 106 may facilitate communications with other networks. For example, the CN 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. For example, the CN 106 may include or may communicate with an IP gateway, such as an IP Multimedia Subsystem (IMS) server, that serves as an interface between the CN 106 and the PSTN 108. Additionally, the CN 106 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers.

[0051] Despite Figures 1A-1D While the WTRU is described in the specification as a wireless terminal, it is contemplated that in certain representative embodiments such a terminal may utilize a (eg, temporarily or permanently) wired communication interface with a communication network.

[0052] In a representative embodiment, the other network 112 may be a WLAN.

[0053] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have access to or an interface with a distribution system (DS) or other type of wired / wireless network that transmits traffic to and / or out of the BSS. Traffic from STAs outside the BSS may arrive through the AP and be delivered to the STA. Traffic originating from the STA to a destination outside the BSS may be sent to the AP for delivery to the respective destination. Traffic between STAs within the BSS may be sent through the AP, for example, where a source STA may send traffic to the AP, and the AP may deliver the traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent between (e.g., directly between) source and destination STAs using direct link setup (DLS). In certain representative embodiments, the DLS may use 802.11e DLS or 802.11z tunneled DLS (TDLS). A WLAN using an independent BSS (IBSS) mode may not have an AP, and STAs (eg, all STAs) within or using the IBSS may communicate directly with each other. The IBSS communication mode may sometimes be referred to herein as an "ad-hoc" communication mode.

[0054] When using 802.11ac infrastructure operation mode or similar operation mode, the AP can transmit beacons on a fixed channel (e.g., a primary channel). The primary channel can be a fixed width (e.g., a 20 MHz wide bandwidth) or a width dynamically set through signaling. The primary channel can be the operating channel of the BSS and can be used by STAs to establish a connection with the AP. In certain representative embodiments, carrier sense multiple access with collision avoidance (CSMA / CA) can be implemented, for example, in an 802.11 system. For CSMA / CA, STAs (e.g., each STA) (including the AP) can sense the primary channel. If the primary channel is sensed / detected and / or determined to be busy by a specific STA, the specific STA can back off. One STA (e.g., only one station) can transmit at any given time in a given BSS.

[0055] High throughput (HT) STAs may communicate using a 40 MHz wide channel, for example, by combining a primary 20 MHz channel with adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0056] Very high throughput (VHT) STAs can support 20MHz, 40MHz, 80MHz and / or 160MHz wide channels. 40MHz and / or 80MHz channels can be formed by combining consecutive 20MHz channels. A 160MHz channel can be formed by combining 8 consecutive 20MHz channels, or by combining two non-contiguous 80MHz channels, which can be referred to as an 80+80 configuration. For the 80+80 configuration, after channel coding, the data can be passed through a segment parser that can divide the data into two streams. Each stream can be subjected to inverse fast Fourier transform (IFFT) processing and time domain processing separately. The stream can be mapped to two 80MHz channels, and the data can be sent by the transmitting STA. At the receiver of the receiving STA, the operations described above for the 80+80 configuration can be reversed, and the combined data can be sent to the media access control (MAC).

[0057] 802.11af and 802.11ah support operating modes below 1 GHz. The channel operating bandwidth and carrier are reduced relative to 802.11af and 802.11ah used in 802.11n and 802.11ac. 802.11af supports 5 MHz, 10 MHz, and 20 MHz bandwidths in the TV White Space (TVWS) spectrum, and 802.11ah supports 1 MHz, 2 MHz, 4 MHz, 8 MHz, and 16 MHz bandwidths using non-TVWS spectrum. According to a representative embodiment, 802.11ah can support meter type control / machine type communications, such as MTC devices in macro coverage areas. MTC devices can have certain capabilities, such as limited capabilities, including support for (e.g., only support for) certain and / or limited bandwidths. MTC devices can include batteries with battery life above a threshold (e.g., to maintain very long battery life).

[0058] WLAN systems that can support multiple channels and channel bandwidths such as 802.11n, 802.11ac, 802.11af, and 802.11ah include a channel that can be designated as a primary channel. The bandwidth of the primary channel can be equal to the maximum common operating bandwidth supported by all STAs in the BSS. The bandwidth of the primary channel can be set and / or limited by the STA among all STAs operating in the BSS, which supports the minimum bandwidth operating mode. In the example of 802.11ah, for a STA that supports (e.g., only supports) 1 MHz mode (e.g., an MTC-type device), the primary channel can be 1 MHz wide, even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) settings can depend on the status of the primary channel. If the primary channel is busy, for example, because a STA (supporting only 1 MHz operating mode) is transmitting to the AP, the entire available frequency band can be considered busy, even if most of the frequency band remains idle and may be available.

[0059] In the United States, the available frequency bands for 802.11ah are from 902MHz to 928MHz. In South Korea, the available frequency bands are from 917.5MHz to 923.5MHz. In Japan, the available frequency bands are from 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is from 6MHz to 26MHz, depending on the country code.

[0060] Figure 1D 1 is a system diagram illustrating the RAN 113 and the CN 115 according to an embodiment. As described above, the RAN 113 may employ NR radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 113 may also be in communication with the CN 115.

[0061] The RAN 113 may include gNBs 180a, 180b, and 180c, though it will be appreciated that the RAN 113 may include any number of gNBs while remaining consistent with an embodiment. The gNBs 180a, 180b, and 180c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In one example, the gNBs 180a, 180b, and 180c may implement MIMO technology. For example, the gNBs 180a and 180b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, and 180c. Thus, for example, the gNB 180a may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a. In one example, the gNBs 180a, 180b, and 180c may implement carrier aggregation technology. For example, the gNB 180a may transmit multiple component carriers to the WTRU 102a (not shown). A subset of these component carriers may be on unlicensed spectrum, while the remaining component carriers may be on licensed spectrum. In one example, the gNBs 180a, 180b, and 180c may implement coordinated multi-point (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNBs 180a and 180b (and / or gNB 180c).

[0062] The WTRUs 102a, 102b, 102c may communicate with the gNB 180a, 180b, 180c using transmissions associated with scalable parameter configurations. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNB 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of varying or scalable lengths (e.g., containing different numbers of OFDM symbols and / or varying absolute time lengths).

[0063] The gNBs 180a, 180b, 180c may be configured to communicate with the WTRUs 102a, 102b, 102c in a standalone configuration and / or a non-standalone configuration. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c without accessing other RANs (e.g., such as the eNode-Bs 160a, 160b, 160c). In a standalone configuration, the WTRUs 102a, 102b, 102c may use one or more of the gNBs 180a, 180b, 180c as mobility anchors. In a standalone configuration, the WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using signals in unlicensed bands. In a non-standalone configuration, the WTRUs 102a, 102b, 102c may communicate / connect with the gNBs 180a, 180b, 180c while also communicating / connecting with another RAN, such as the eNode-Bs 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement DC principles to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-Bs 160a, 160b, 160c may serve as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0064] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in UL and / or DL, support of network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data towards a user plane function (UPF) 184a, 184b, routing of control plane information towards an access and mobility management function (AMF) 182a, 182b, etc. Figure 1D As shown, gNBs 180a, 180b, and 180c can communicate with each other via the Xn interface.

[0065] Figure 1DThe CN 115 shown in FIG may include at least one AMF 182 a, 182 b, at least one UPF 184 a, 184 b, at least one session management function (SMF) 183 a, 183 b, and possibly a data network (DN) 185 a, 185 b. While each of the aforementioned elements is depicted as part of the CN 115, it should be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0066] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N2 interface and may serve as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRU 102a, 102b, 102c, supporting network slicing (e.g., handling different PDU sessions with different requirements), selecting a specific SMF 183a, 183b, managing registration areas, termination of NAS signaling, mobility management, etc. The AMF 182a, 182b may use network slicing to customize CN support for the WTRU 102a, 102b, 102c based on the type of service being utilized by the WTRU 102a, 102b, 102c. For example, different network slices may be established for different use cases, such as services relying on ultra-reliable low latency (URLLC) access, services relying on enhanced massive mobile broadband (eMBB) access, services for machine type communication (MTC) access, and / or the like. The AMF 182 may provide a control plane function for switching between the RAN 113 and other RANs (not shown) employing other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies such as WiFi.

[0067] The SMFs 183a and 183b can connect to the AMFs 182a and 182b in the CN 115 via the N11 interface. The SMFs 183a and 183b can also connect to the UPFs 184a and 184b in the CN 115 via the N4 interface. The SMFs 183a and 183b can select and control the UPFs 184a and 184b and configure traffic routing through the UPFs 184a and 184b. The SMFs 183a and 183b can perform other functions, such as managing and allocating UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notifications. The PDU session type can be IP-based, non-IP-based, Ethernet-based, and so on.

[0068] The UPF 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via the N3 interface and 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 UPF 184, 184b may perform other functions, such as routing and forwarding packets, enforcing user plane policies, supporting multi-homed PDU sessions, handling user plane QoS, buffering downlink packets, providing mobility anchoring, etc.

[0069] The CN 115 may facilitate communications with other networks. For example, the CN 115 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that serves as an interface between the CN 115 and the PSTN 108. Furthermore, the CN 115 may provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired and / or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to a local data network (DN) 185a, 185b through the UPFs 184a, 184b via the N3 interface to the UPFs 184a, 184b and the N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0070] Given that Figures 1A-1D as well as Figures 1A-1D

[0015] As described herein, one or more or all of the functionality described herein with respect to one or more of the following may be performed by one or more emulated devices (not shown): the WTRUs 102a-d, base stations 114a-b, eNodeBs 160a-c, MMEs 162, SGWs 164, PGWs 166, gNBs 180a-c, AMFs 182a-b, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other devices described herein. An emulated device may be one or more devices configured to emulate one or more or all of the functionality described herein. For example, an emulated device may be used to test other devices and / or simulate network and / or WTRU functionality.

[0071] Emulation devices can be designed to implement one or more tests of other devices in a laboratory environment and / or in a carrier network environment. For example, one or more emulation devices can perform one or more or all functions while being fully or partially implemented and / or deployed as part of a wired and / or wireless communication network in order to test other devices within the communication network. One or more emulation devices can perform one or more or all functions while being temporarily implemented / deployed as part of a wired and / or wireless communication network. A emulation device can be directly coupled to another device for the purpose of testing and / or can perform tests using over-the-air wireless communications.

[0072] One or more emulation devices can perform one or more (including all) functions rather than being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation device can be used in a test scenario in a test lab and / or a non-deployed (e.g., testing) wired and / or wireless communication network to enable testing of one or more components. The one or more emulation devices can be test devices. Direct RF coupling and / or wireless communication via RF circuitry (e.g., which can include one or more antennas) can be used by the emulation device to send and / or receive data.

[0073] The WTRU may use one or more channel state information reference signals (CSI-RS) to perform measurements. The CSI-RS may be sent using a wideband (e.g., across the system bandwidth) with a duty cycle (e.g., 5, 10, 20, 40, 80 ms) that may be in the physical downlink shared channel (PDSCH) region. There may be a certain number of CSI-RS patterns in a subframe (e.g., 20 CSI-RS patterns, less than 20 CSI-RS patterns, more than 20 CSI-RS patterns). The CSI-RS pattern may be a CSI-RS reuse pattern. The CSI-RS pattern may be a function of the number of antenna ports that may be used at the transmitting device.

[0074] Figure 2 A diagram 200 is shown including an exemplary representation of reference signals (RS) 210, 220, 230. The RS 210, 220, 230 may include a CSI-RS pattern that may be based on the number of antenna ports that may be used for transmission. Figure 2 In each shown RS, the same indication of one or more resource elements (REs) (e.g., Figure 2 The same shading shown in the figure may indicate a set of one or more REs that may be associated with a CSI-RS configuration and / or a CSI-RS pattern. Note that in this disclosure, CSI-RS pattern, CSI-RS reuse pattern, CSI-RS pattern reuse, and CSI-RS configuration may be used interchangeably.

[0075] exist Figure 2 , exemplary CSI-RS patterns for each of 2 (e.g., RS 210), 4 (e.g., RS 220), and 8 (e.g., RS 230) antenna ports are shown. One or more CSI-RS reuse patterns for the 2, 4, and 8 antenna ports may be aggregated to form a CSI-RS pattern, e.g., where more than 8 antenna ports may be used.

[0076] A CSI-RS configuration may refer to a configuration of one or more reference signals to be transmitted for the purpose of CSI measurement. The examples described herein may be illustrated in terms of a WTRU receiving a CSI-RS configuration that defines one or more reference signals to be transmitted by the WTRU in the uplink; however, the WTRU may also receive a CSI-RS configuration that defines one or more reference signals to be received in the downlink. For example, the WTRU may receive a first CSI-RS configuration that defines one or more CSI-RS (e.g., time / frequency location, power level, periodicity, hopping pattern, code, etc.). The WTRU may then transmit the CSI-RS in accordance with the configuration, for example, periodically and / or aperiodically based on a trigger. The trigger may indicate which portions of the CSI configuration are applicable to a given aperiodic CSI-RS transmission. For example, the trigger (e.g., DCI) may indicate whether the CSI-RS is to be transmitted using a non-zero power RS ​​or a zero power CSI RS (e.g., to perform muting).

[0077] In an example where the WTRU receives downlink CSI-RS, the WTRU may receive a second CSI-RS configuration that defines one or more CSI-RS (e.g., time / frequency location, power level, periodicity, hopping pattern, code, etc.). The WTRU may then receive the CSI-RS according to the configuration, for example, periodically and / or aperiodically based on a trigger. The trigger may indicate which portions of the CSI configuration are applicable for a given aperiodic CSI-RS transmission. For example, the trigger (e.g., DCI) may indicate whether to receive the CSI-RS according to the first CSI-RS pattern or the second CSI-RS pattern.

[0078] In an example, a WTRU receives a CSI-RS configuration that defines multiple possible CSI-RS transmissions (e.g., CSI-RS downlink transmissions). In some subframes, each possible CSI-RS transmission may be performed, for example, by the eNB sending a CSI-RS transmission according to the CSI-RS configuration. A DCI may be used to indicate to the WTRU that the eNB will send a CSI-RS transmission according to the CSI-RS configuration in that subframe. In an example, not all CSI-RS transmissions that the WTRU is to send may be applicable to the WTRU, otherwise the WTRU may not be able to measure. For example, a first DCI may be used to indicate multiple CSI-RS that are active for a subframe. A second DCI may indicate a subset of the multiple CSI-RS that are active and should be measured by the WTRU. The WTRU may use the first DCI and the second DCI to determine which of the multiple CSI-RS should be measured (e.g., the indicated subset) and which of the multiple CSI-RS should be silenced (e.g., the active set minus the indicated subset). The WTRU may perform muting of REs that include active CSI-RS that are not measured by the WTRU by performing rate matching and / or other techniques described herein on these resource elements. Rate matching may be performed in order to receive a PDSCH transmission that includes resource elements to be muted.

[0079] Note that as used herein, “DCI” may refer to “downlink control indicator” or “downlink control information.” “Downlink control indicator,” “downlink control information,” and “DCI” may be used interchangeably herein.

[0080] One or more channels and / or channel types may be used to report CSI feedback. For example, either or both of the physical uplink control channel (PUCCH) or the physical uplink shared channel (PUSCH) may be used to report CSI feedback. For example, the PUCCH channel may provide CSI feedback while, for example, utilizing limited feedback overhead. For example, the PUSCH channel may provide a relatively large amount of feedback overhead while, for example, providing relatively low reliability. The PUCCH channel may be used for periodic CSI feedback, for example, where coarse link adaptation may be used. The PUSCH channel may be used when triggering aperiodic CSI reporting, for example, where finer link adaptation may be used.

[0081] The CSI feedback may include at least one of a rank indicator (RI), a precoder matrix index (PMI), and a channel quality indicator (CQI) (e.g., the CSI may be reported in a format that may include at least one of the RI, PMI, and CQI). For example, the RI and / or PMI may be calculated at the WTRU receiver by the WTRU selecting (e.g., from a predefined codebook) a rank and / or precoding matrix that may increase the WTRU throughput. The PMI and / or CQI may be assigned to and / or reported as associated with one or more categories, such as wideband, subband, and WTRU-selected subband. The RI may be reported (e.g., only) using wideband. Table 1 shows example scheduling modes that may be associated with the PUCCH and / or PUSCH. Table 2 shows example values ​​that may be used for CSI feedback depending on the transmission mode and / or reporting mode (e.g., periodic or aperiodic).

[0082] Scheduling Mode Periodic CSI reporting channel Aperiodic CSI reporting channel Frequency non-selective PUCCH Frequency selectivity PUCCH PUSCH

[0083] Table 1 Reporting modes for LTE and / or LTE-A

[0084]

[0085] Table 2 CSI feedback information according to reporting mode

[0086] Periodic and / or aperiodic feedback (e.g., CSI feedback) may be sent on the PUCCH channel. Periodic and / or aperiodic feedback may also or instead be sent on the PUSCH channel, for example, when the WTRU has been provided with a PUSCH channel allocation and / or is otherwise available.

[0087] Periodic reporting may use one or more types of reports and / or one or more sequences of one or more types of reports. The report type may be, for example, one or more of report type 1 (e.g., may be associated with subband CQI), report type 2 (e.g., may be associated with wideband CQI / PMI), report type 3 (e.g., may be associated with RI), and / or report type 4 (e.g., may be associated with wideband CQI).

[0088] For example, aperiodic CSI (e.g., CSI feedback) may be requested via an uplink grant (e.g., downlink control indicator (DCI) format 0, DCI format 4). For example, aperiodic CSI (e.g., CSI feedback) may be requested when a CQI request bit may be set in the associated DCI. For example, aperiodic CSI (e.g., CSI feedback) may be sent on the PUSCH.

[0089] For example, when eight (8) transmit (Tx) antenna ports may be used, the CSI reporting types (e.g., periodic CSI reporting types) may include one or more reporting types. Such reporting types may include one or more of a type 1 report (e.g., may support CQI feedback for a subband selected by the WTRU) and a type 1a report (e.g., may support subband CQI and / or second PMI feedback). Such reporting types may also or alternatively include one or more of a type 2, type 2b, and / or type 2c report (e.g., each report may support wideband CQI and / or PMI feedback). Such reporting types may also or alternatively include one or more of a type 2a report (e.g., may support wideband PMI feedback), a type 3 report (e.g., may support RI feedback), a type 4 report (e.g., may support wideband CQI), a type 5 report (e.g., may support RI and / or wideband PMI feedback), and a type 6 report (e.g., may support RI and / or PTI feedback).

[0090] An exemplary Type 6 report may include and / or use a precoding type indicator (PTI) for eight (8) transmit antenna ports, eg, where an 8Tx (eight transmit ports) precoder may be defined with a dual codebook.

[0091] For example, RE muting may be used to avoid signal collisions. Where RE muting may be used, puncturing and / or rate matching may be used, for example, from a coding chain perspective. Where puncturing may be used, signals that may be mapped to a punctured RE may not be transmitted and / or may be transmitted with zero (0) power in such a punctured RE. Where rate matching may be used, mapping one or more signals to one or more REs may help avoid mapping to one or more specific REs, which may, for example, result in other signals not being transmitted.

[0092] The N-bit coded bit sequence used for the channel, for example (c1,…,c N ), which may be the output of a channel encoder, which may have payload and / or information as input. Such a channel encoder may use any channel code, such as turbo codes, convolutional codes, Reed-Muller codes, etc. Such a coded bit sequence may be the input of a mapper.

[0093] M-symbol modulation symbol sequence, such as (x1,…,x M ), which may be the output of the mapper, where the coded bit sequence may be modulated according to a modulation scheme such as binary phase shift keying (BPSK), quadrature phase shift keying (QPSK), 16-quadrature amplitude modulation (16QAM), or 64-quadrature amplitude modulation (64QAM). The modulation symbol sequence of length M may be equal to or less than N, for example, based on the modulation scheme that may be used.

[0094] The modulated symbol sequence may be mapped to a set of one or more REs for the channel, for example, according to a predefined order. For example, x1,…,x M The puncturing may indicate that the modulation symbol x may be mapped to the M REs for the channel in a specific order (eg, a predefined order). If the kth (eg, where k≤M) RE may be muted (eg, due to a collision), the puncturing may indicate that the modulation symbol x may be mapped to the M REs for the channel in a specific order (eg, a predefined order). k Rate matching may indicate that the mapping may skip one or more REs that may be muted and / or may map fewer modulation symbols.

[0095] M-1 modulation symbols may be mapped and / or transmitted for one or more rate-matched REs. For example, x1, ..., x M-1 The last modulation symbol may not be sent due to the silence of the kth RE. Puncturing may lose coded bits in the position of the silent RE. Rate matching may lose coded bits from the last coded bit.

[0096] RE muting by puncturing may be referred to herein as “RE puncturing.” RE muting by rate matching may be referred to herein as “RE rate matching.” As used herein, RE muting may include either or both of RE puncturing and RE rate matching.

[0097] For example, RE muting may be performed (e.g., in LTE systems) to avoid collisions between different types of signals in the same direction. For example, in the downlink (DL), PDSCH REs may be muted to avoid collisions with one or more CSI-RS and / or one or more Positioning Reference Signal (PRS) REs. Such CSI-RS and / or PRS REs may be muted to avoid collisions with the Primary Synchronization Signal (PSS) and / or Secondary Synchronization Signal (SSS). Uplink channels (UL) that may use PUSCH and / or PUCCH may be shortened in an effort to avoid collisions with Sounding Reference Signals (SRS) in the UL.

[0098] The enhanced physical downlink control channel (EPDCCH) can be used to achieve frequency domain inter-cell interference coordination (ICIC) and / or beamforming gain. EPDCCH, ePDCCH, and E-PDCCH can be used interchangeably in this article. Enhanced resource element groups (EREGs) and enhanced control channel elements (ECCEs) can be used interchangeably in this article and may also be referred to as eREGs and eCCEs, respectively. For example, since multiple EREGs can be used to form an ECCE, EPDCCH resources can be equivalently described in terms of EREGs or ECCEs.

[0099] EPDCCH resources for a WTRU-specific search space may be configured with a subset of physical resource blocks (PRBs) in the PDSCH region. EPDCCH resources may be configured in a WTRU-specific manner. EPDCCH resource sets (e.g., up to two EPDCCH resource sets) may be configured for a WTRU. EPDCCH resource sets may be configured with 2, 4, or 8 PRB pairs. EPDCCH resource sets may be determined as localized resource sets and / or distributed resource sets.

[0100] One or more PRB pairs may be configured as EPDCCH resources. In each such PRB pair, the number of EREGs may be defined. For example, sixteen (16) EREGs may be defined for each such PRB pair, e.g., regardless of the cyclic prefix (CP) length (e.g., normal CP, extended CP).

[0101] Figure 3 An exemplary eREG definition 300 of a PRB pair in a CP subframe is shown. REs used for such an eREG may be cyclically allocated in a frequency-first manner and / or may be rate matched based on a demodulation reference signal (DM-RS) (e.g., antenna ports 307, 308, 309, 310, as shown in FIG. Figure 3 This may result in randomization of the channel estimation performance across eREGs, as the channel estimation performance may be different depending on the position of the RE in the PRB pair.

[0102] ECCEs may be defined by groupings of, for example, four (4) or eight (8) EREGs within an EPDCCH resource set. The total number of ECCEs in an EPDCCH resource set (which may be indicated as N eCCE,set ) may be based on the number of PRB pairs configured for such an EPDCCH resource set (which may be indicated as N PRB,set ) and / or the number of EREGs that can be grouped for ECCE (which can be represented as N eREG ) is determined. For example, N eCCE,set =16x N PRB,set / N eREG For an EREG that may be associated with another ECCE, the EREG of an ECCE may be mutually exclusive.

[0103] Two or more types of ECCEs may be determined based on the operating mode of the EPDCCH resource set (e.g., localized operating mode, distributed operating mode). ECCEs used in localized operating mode may be referred to as localized ECCEs (L-ECCEs). ECCEs used in distributed operating mode may be referred to as distributed ECCEs (D-ECCEs).

[0104] To form an L-ECCE, multiple EREGs (eg, four (4) or eight (8) EREGs) located in the same PRB pair may be grouped together.

[0105] EREGs in different PRB pairs may be grouped to form a D-ECCE.

[0106] The EREG in the EPDCCH resource set can be used to form L-ECCEs and / or D-ECCEs based on the operation mode of the EPDCCH that can be configured for the associated EPDCCH resource set. For example, the EPDCCH resource set can be configured with a localized operation mode (e.g., a localized EPDCCH). The EREG in such an EPDCCH resource set can be used to form L-ECCEs. The EPDCCH resource set may include ECCEs that can be L-ECCEs or D-ECCEs.

[0107] Table 3 shows an exemplary number of EREGs that can be grouped to form an ECCE based on an exemplary subframe configuration. For example, four (4) EREGs can be grouped to form an ECCE, for example, for normal subframes and / or special subframe configurations 3, 4, and 8 in time division duplex (TDD), where each ECCE can obtain a sufficient number of REs to use a specific effective coding rate.

[0108] Table 3 also shows an exemplary number of eight (8) EREGs that can be grouped to form an ECCE, e.g., for normal subframes and / or special subframe configurations 1, 2, 6, 7, 9 and / or special subframe configurations 1, 2, 3, 5, 6 in time division duplex (TDD), where each ECCE can have a sufficient number of REs to use a particular effective coding rate.

[0109]

[0110] Table 3 Number of examples of grouped EREGs per ECCE

[0111] The WTRU-specific search space may be used with the EPDCCH. The common search space may be located (e.g., always located) in the PDCCH region. The WTRU monitoring behavior for downlink control signaling reception may be defined in a downlink subframe as the WTRU monitoring the WTRU-specific search space in the EPDCCH and the common search space in the PDCCH, where the EPDCCH monitoring subframe may be configured via higher layer signaling. The WTRU monitoring behavior for downlink control signaling reception may also or alternatively be defined in a downlink subframe as the WTRU monitoring the WTRU-specific search space in the PDCCH and the common search space. In the case where a subframe may be configured to monitor an EPDCCH subframe, if the EPDCCH may not be available in such a subframe due to, for example, a collision between the EPDCCH REs and other signals, a WTRU-specific search space fallback may be used so that the WTRU may monitor the PDCCH for the WTRU-specific search space.

[0112] Table 4 shows the ECCE ), which may be the number of available REs (n) for EPDCCH in a PRB pair. EPDCCH ). When the number of available REs may be less than a threshold (e.g., n EPDCCH <104), the aggregation level can be increased in an effort to maintain a similar effective coding rate. For example, it can be used for n EPDCCH One or more supportable EPDCCH formats for localized transmission of <104 can be N ECCE ∈{2,4,8,16}, while in other cases (e.g., where n EPDCCH ≥104) can use N ECCE ∈{1,2,4,8}. The set of aggregation levels may be based on the EPDCCH transmission mode.

[0113]

[0114] Table 4 Examples of supported EPDCCH formats

[0115] EPDCCH RE can be defined as RE in a PRB pair. EPDCCH RE may be or may not be Figure 4 REs occupied by antenna ports {407, 408, 409, 410} are shown in FIG. 4 as components of the exemplary EPDCCH RE definitions 420 and 430 shown in block diagram 400.

[0116] Figure 4Example EPDCCH RE definitions 420 and 430 for PRB pairs are shown that are based on CP length and do not conflict with other signals. The result in such an example can be 144 available REs (as shown in EPDCCH RE definition 420) and / or 128 available REs (as shown in EPDCCH RE definition 430) for normal CP and extended CP, respectively.

[0117] EPDCCH resources may be configured in the PDSCH region such that REs for the EPDCCH may collide with one or more other signals, such as, but not limited to, CSI-RS, CRS, PRS, PBCH, SCH, and PDCCH. When REs collide with one or more other signals, the WTRU behavior may include rate matching coded bits for the EPDCCH for the REs that collide with the CSI-RS, CRS, and / or PDCCH. When REs collide with one or more other signals, the WTRU behavior may also or alternatively include using PRB pairs for PBCH and SCH in subframes that may not be used for EPDCCH. If other signals can be transmitted in the PRB pairs configured for EPDCCH, the available REs for EPDCCH may be reduced.

[0118] The WTRU may monitor and / or attempt to decode a set of EPDCCH candidates in a subframe or TTI, where the EPDCCH candidates may be determined based on the ECCE aggregation level, the starting ECCE number, and / or the operation mode (e.g., localized, distributed). The terms "EPDCCH candidate" and "EPDCCH decoding candidate" may be used interchangeably herein.

[0119] The EPDCCH candidate set for the WTRU-specific search space may be determined in a WTRU-specific manner.The EPDCCH candidate set for the common search space may be determined in a cell-specific manner.

[0120] The number of PRB pairs configured for the EPDCCH resource set, the available REs in the subframe (n EPDCCH ), EPDCCH search space type (e.g., common search space, WTRU-specific search space), subframe type (e.g., normal subframe, special subframe), cyclic prefix (CP) length (e.g., normal CP, extended CP) and / or EPDCCH operation mode (e.g., localized, distributed), determine the ECCE aggregation level set associated with the EDCCH candidates in the EPDCCH search space.

[0121] Table 5 and Table 6 are based on the number of PRB pairs configured for the EPDCCH resource set. An example of a set of ECCE aggregation levels (L) and a related number of EPDCCH candidates is provided for each ECCE aggregation level in the EPDCCH search space.

[0122]

[0123] Table 5 may be used by the WTRU based on the number of available REs (n EPDCCH ) Example of a set of EPDCCH candidates monitoring a distributed EPDCCH

[0124]

[0125] Table 6 may be used by the WTRU based on the number of available REs (n EPDCCH ) Example of monitoring the number of EPDCCH candidates for localized EPDCCH

[0126] CSI-RS transmissions may be used for CSI measurement and / or for CSI reporting. CSI-RS transmissions may (in some examples only) be transmitted in a periodic manner, for example, based on a higher layer configuration. When a WTRU may be triggered for CSI reporting, the WTRU may (in some examples already) have CSI configuration information for CSI reporting. For example, periodic CSI-RS transmissions may require more reference signal overhead and / or provide less flexibility than using WTRU-specific CSI-RS transmissions.

[0127] Aperiodic CSI-RS transmission may be used to reduce reference signal overhead. Aperiodic CSI-RS transmission may be used for aperiodic CSI reporting. The presence of an aperiodic CSI-RS may be dynamically indicated for aperiodic CSI-RS reporting. For example, the performance of downlink channels in subframes that may contain an aperiodic CSI-RS may be degraded. For example, when the WTRU may not be aware of the presence of an aperiodic CSI-RS, the aperiodic CSI-RS may interfere with other downlink channels. For example, the WTRU may not receive a dynamic indication of the presence of an aperiodic CSI-RS. Such a WTRU may also not be able to receive other downlink channels in the same subframe.

[0128] A WTRU may be configured to monitor the EPDCCH. Such a WTRU may not receive an indication of the presence of aperiodic CSI-RS before the WTRU may begin attempting to decode the configured EPDCCH search space, for example, where a dynamic indication of the presence of aperiodic CSI-RS may be signaled in the EPDCCH search space. This may degrade EPDCCH performance.

[0129] Aperiodic (e.g., triggered) CSI-RS transmission and / or reporting may increase the flexibility of CSI-RS transmission in a WTRU-specific manner. CSI-RS transmission and / or associated CSI reporting may be based on a trigger, such as an eNodeB trigger.

[0130] The eNodeB may trigger an aperiodic CSI report in a subframe (e.g., subframe n). The associated measurement reference signal (e.g., CSI-RS) for such a subframe may be transmitted in the same subframe (e.g., subframe n) and / or in one or more adjacent subframes (e.g., subframes n-2, n-1, n+1, n+2, etc.).

[0131] The triggering of aperiodic CSI reporting may be based on an indication that may be signaled, monitored, and / or decoded (e.g., by a WTRU) in a subframe or a subset of subframes. The indication of the aperiodic CSI reporting trigger may be an implicit indication or an explicit indication.

[0132] The terms "aperiodic CSI report," "A-CSI report," "A-CSI," "triggered CSI report," "triggered CSI report," "PUSCH-based CSI report," "CSI report on PUSCH," "dynamic indication-based CSI report," "indication-based CSI report," and "one-time CSI report" are used interchangeably herein. The terms "subframe," "transmission time interval (TTI)," and "time unit for transmission" are also used interchangeably herein. The terms "aperiodic measurement reference signal," "triggered measurement reference signal," "CSI-RS," "aperiodic CSI-RS," "aperiodic CSI-IM," "A-CSI-IM," "A-CSI-RS," "CSI-RS-based triggering," "one-time CSI-RS," "dynamic indication-based CSI-RS," "CSI-RS resources indicated in the downlink control indicator (DCI)," and "CSI-RS associated only with A-CSI" are also used interchangeably herein. The terms “A-CSI-RS,” “RE position of A-CSI-RS in a subframe,” “A-CSI-RS configuration,” “time and frequency position of A-CSI-RS,” “A-CSI-RS pattern,” “A-CSI-RS reuse pattern,” and “A-CSI-RS position” are also used interchangeably herein.

[0133] The associated measurement reference signal for A-CSI reporting may be sent, signaled, received, and / or measured (e.g., by a WTRU) aperiodically. The aperiodic measurement reference signal for A-CSI reporting may be referred to herein as "apperiodic CSI-RS."

[0134] A CSI-RS that is transmitted periodically may be referred to as a "P-CSI-RS" and may be used interchangeably with a CSI-RS that is configured by higher layers. The WTRU may know that a P-CSI-RS is present in a subframe before such a WTRU may start receiving signals from the subframe. A CSI-RS that is transmitted aperiodically may be referred to as an "A-CSI-RS". The presence of an A-CSI-RS in a subframe may be determined based on a dynamic indication. The dynamic indication of the presence of an A-CSI-RS may be associated with one or more subframes. The dynamic indication of the presence of an A-CSI-RS may be used for activation and / or deactivation of the A-CSI-RS. For example, such an indication may activate an A-CSI-RS, which may be transmitted periodically until deactivated.

[0135] A complete CSI configuration (e.g., complete CSI configuration information), for example, for P-CSI-RS, may be configured via a higher layer (e.g., RRC signaling). The complete CSI configuration may include, for example, one or more of a CSI-RS pattern, the number of CSI processes, a duty cycle of CSI-RS transmission, the number of CSI-RS ports, a time / frequency position of CSI-RS, and a transmission power of CSI-RS.

[0136] A partial CSI configuration (e.g., partial CSI configuration information) may be configured via higher layers (e.g., RRC signaling), e.g., for A-CSI-RS. A partial CSI-RS configuration may include a subset of a full CSI configuration. A partial CSI-RS configuration may include, for example, one or more CSI-RS patterns and / or one or more indications thereof. A full CSI configuration or a subset of a partial CSI configuration may be dynamically indicated, for example, from a DCI (e.g., a DCI that may trigger an A-CSI report). In an example, the DCI may indicate that one or more portions (e.g., all or part) of a CSI configuration may be applicable for a given CSI-RS transmission. For example, at least one CSI-RS pattern that may be used in a subframe and / or the presence of a configured CSI-RS pattern may be dynamically indicated (e.g., from the DCI).

[0137] One or more A-CSI-RS may be indicated to a WTRU in a subframe. For example, the A-CSI-RS may be categorized into two or more types. A first type of A-CSI-RS may be used for CSI measurement and / or RE muting of one or more other physical channels. This first type of A-CSI-RS may be a non-zero power A-CSI-RS for a WTRU. This first type of A-CSI-RS for a first WTRU may be considered, determined, and / or used as a second type of A-CSI-RS for a second WTRU.

[0138] In some examples, a second type of A-CSI-RS may be used for RE muting of one or more other downlink physical channels, or for RE muting of only one or more downlink physical channels. This RE muting may be punctured and / or rate matched. The second type of A-CSI-RS may be a zero-power A-CSI-RS for the WTRU. RE muting may correspond to the WTRU suppressing and / or attempting to avoid transmitting any signal energy on the A-CSI-RS resources. The second type of A-CSI-RS for a first WTRU may be considered, determined, and / or used as the first type of A-CSI-RS for a second WTRU.

[0139] Herein, the first type of A-CSI-RS may be referred to as a “Type-1 A-CSI-RS.” Herein, the second example type of A-CSI-RS may be referred to as a “Type-2 A-CSI-RS.”

[0140] A WTRU may receive an indication of one or more Type-1A-CSI-RSs. Such a WTRU may measure CSI from the indicated one or more Type-1A-CSI-RSs and consider, determine, and / or assume that each RE occupied by the one or more Type-1A-CSI-RSs may be a silent RE for receiving one or more downlink channels (e.g., PDSCH, EPDCCH) that may be scheduled for the WTRU.

[0141] A WTRU may receive an indication of one or more Type-2A-CSI-RSs. Such a WTRU may consider, determine, and / or assume that each RE occupied by one or more Type-2A-CSI-RSs may be a silent RE for reception of a downlink channel that may be scheduled for the WTRU. For example, a WTRU may be scheduled for a PDSCH in a subframe, and such a WTRU may receive an indication that one or more Type-2A-CSI-RSs may be in the same subframe. Such a WTRU may consider each RE occupied by the indicated Type-2A-CSI-RSs to be a silent RE for reception of a scheduled PDSCH.

[0142] A WTRU may be configured with one or more A-CSI-RSs and / or one or more P-CSI-RSs for CSI reporting and / or RE muting for one or more downlink physical channels. The CSI-RS configuration for the A-CSI-RS may be different from the CSI-RS configuration for the P-CSI-RS. The CSI-RS configuration may include, but is not limited to, at least one of the number of antenna ports, scrambling sequence, duty cycle, starting offset, transmit power, and reuse pattern.

[0143] The WTRU may be instructed, configured, and / or determined to receive, measure, and / or process one or more A-CSI-RS and / or one or more P-CSI-RS in the same subframe. For example, the WTRU may be configured with a P-CSI-RS for CSI reporting and may be instructed to receive and / or measure the A-CSI-RS in a subframe in which the configured P-CSI-RS may be transmitted.

[0144] A WTRU may measure A-CSI based on the P-CSI-RS. Such a WTRU may be instructed to report A-CSI in subframes where the A-CSI-RS may not be indicated. The P-CSI-RS used for such A-CSI measurement may be located in the same subframe or in a previous subframe. The WTRU may be instructed to report A-CSI in a subframe and may assume that the A-CSI-RS may be transmitted in the subframe.

[0145] The WTRU may be independently indicated for each of an A-CSI reporting request and an A-CSI-RS indication, where such an A-CSI-RS indication may include at least one indication of the presence or absence of an A-CSI-RS, configuration information of the A-CSI-RS, and an A-CSI-RS configuration index.

[0146] A bit field may be used to indicate an A-CSI report request and / or an A-CSI-RS presence indication. For example, one or more states from a bit field may be indicated to trigger an A-CSI report and / or indicate the presence of one or more A-CSI-RSs. Two bits may be used to indicate an A-CSI report trigger and an A-CSI-RS presence indication (e.g., 00 may indicate an A-CSI report trigger with an A-CSI-RS absence, 01 may indicate an A-CSI report trigger with an A-CSI-RS presence, 10 may indicate no A-CSI trigger and A-CSI-RS presence, and 11 may be reserved). An indication of an A-CSI-RS presence without an A-CSI trigger may be used to indicate that RE muting may be performed for one or more other physical channels.

[0147] A bit field for type-1A-CSI-RS indication may be located and / or used in DCI associated with uplink transmissions (e.g., DCI formats 0 / 4). A bit field for type-2A-CSI-RS indication may be located and / or used in DCI associated with downlink transmissions (e.g., DCI formats 1 / 2 / 2A / 2B / 2C).

[0148] A bit field for Type-1 A-CSI-RS indication may be located in a DCI associated with an uplink grant. A bit field for Type-1 and Type-2 A-CSI-RS indication may be located and / or used in a DCI that may be dedicated to A-CSI-RS indication. The bit field for Type-1 and Type-2 A-CSI-RS indication may be used as an indication of a superset of the A-CSI-RS configuration in a subframe. A bit field in a DCI associated with an uplink grant that may indicate a Type-1 A-CSI-RS may be used as a subset of the A-CSI-RS configuration.

[0149] A bit field that may be used (e.g., commonly used) for one or more A-CSI-RS configurations for one or more WTRUs in a subframe may be located and / or used in a common DCI that may be monitored by one or more WTRUs. A WTRU may receive one or more Type-1 A-CSI-RS indications in a WTRU-specific DCI (e.g., DCI format 0 / 4) in the same subframe. The indicated Type-1 A-CSI-RS configuration may be a subset of the one or more A-CSI-RS configurations that may be indicated from the common DCI.

[0150] A WTRU that may receive one or more type-1 A-CSI-RS configurations may consider other A-CSI-RS configurations in the common DCI that may not be in the type-1 A-CSI-RS configuration, such as a type-2 A-CSI-RS configuration. A WTRU that may not receive one or more type-1 A-CSI-RS configurations may consider one or more A-CSI-RS configurations (e.g., all A-CSI-RS configurations) in the common DCI as type-2 A-CSI-RS configurations.

[0151] When the WTRU may be directed (e.g., instructed) to report A-CSI in a subframe, the WTRU may receive an indication of a CSI-RS that may be used for A-CSI reporting between an A-CSI-RS and a P-CSI-RS. Such an A-CSI-RS may be located in the same subframe that may include the received indication of the CSI-RS. Such a P-CSI-RS may be located in the same subframe and / or in one or more adjacent subframes.

[0152] One or more A-CSI-RS configurations may be indicated in a common DCI that may be monitored in a common search space.One or more P-CSI-RS configurations may be configured via higher layer signaling such as RRC signaling.

[0153] The DCI that may be used to request an A-CSI report may include a bit field that may indicate one or more CSI-RS configurations that may be used for measurement of the A-CSI report between the A-CSI-RS and the P-CSI-RS.

[0154] One or more Radio Network Temporary Identifiers (RNTIs) may be used for an A-CSI reporting request, and each RNTI may be scrambled using one or more Cyclic Redundancy Checks (CRCs) for the DCI. Such an A-CSI reporting request may be used to indicate a CSI-RS configuration that may be used for A-CSI reporting between measuring A-CSI-RS and P-CSI-RS. The WTRU may use P-CSI-RS for A-CSI reporting, where a cell-RNTI (C-RNTI) may be used. Such a WTRU may also or alternatively use A-CSI-RS for A-CSI reporting, where a C-RNTI+1 may be used.

[0155] A WTRU may receive a DL signal in a subframe that may contain one or more A-CSI-RSs and / or one or more P-CSI-RSs. One or more of these A-CSI-RSs and / or one or more P-CSI-RSs may be used for RE muting of downlink signals. A WTRU may receive a PDSCH in a subframe that may contain one or more A-CSI-RSs and / or one or more P-CSI-RSs. Such a WTRU may assume, consider, and / or determine that REs occupied by A-CSI-RSs and / or P-CSI-RSs are muted.

[0156] A WTRU may assume and / or determine that REs that may be occupied, used, and / or allocated by CSI-RS (e.g., A-CSI-RS, P-CSI-RS) in a PDSCH resource may be muted REs for an associated PDSCH transmission. Such a WTRU may determine that the muted REs for an associated PDSCH transmission may be punctured REs and / or rate-matched REs, for example, based on one or more criteria that may be determined by such a WTRU.

[0157] Such a standard may include one type of A-CSI-RS. For example, puncturing may be used for type-1 A-CSI-RS and rate matching may be used for type-2 A-CSI-RS, or vice versa.

[0158] Such criteria may also or alternatively include periodic or aperiodic characteristics of the RS. For example, rate matching may be used for P-CSI-RS and puncturing may be used for A-CSI-RS, or vice versa.

[0159] Such criteria may also or alternatively include the modulation order of the PDSCH that may be used for scheduling. For example, puncturing may be used for lower modulation orders (e.g., QPSK) while rate matching may be used for higher modulation orders (e.g., 16QAM, 64QAM), or vice versa.

[0160] Such criteria may also or alternatively include a coding rate or effective coding rate of the PDSCH that may be used for scheduling. For example, puncturing may be used for a coding rate or effective coding rate that may be lower than a threshold, while rate matching may be used for a coding rate or effective coding rate that may be equal to or higher than the threshold, or vice versa. In another example, puncturing may be used for a transport block size (TBS) that may be lower than a threshold, while rate matching may be used for a TBS that may be equal to or higher than the threshold, or vice versa. Such thresholds may be predefined and / or configured.

[0161] Such criteria may also or alternatively include the number and / or rank of codewords. For example, if the number of codewords is one (e.g., rank=1), puncturing may be used, and if the number of codewords is higher than one (e.g., rank>1), rate matching may be used, and vice versa.

[0162] Such criteria may also or alternatively include an indication that may be included in the DCI. For example, a bit field may indicate that muted REs of scheduled PDSCH (where REs may be muted due to CSI-RS) may be rate matched and / or punctured around demodulation.

[0163] RE muting may be used for one or more scheduled PDSCH REs that may have collided with CSI-RS. The use of RE muting may be determined based on one or more criteria that may be determined by the WTRU. Such criteria may include a type of A-CSI-RS. For example, the WTRU may assume that RE muting may be used for Type-1 A-CSI-RS and no RE muting may be used for Type-2 A-CSI-RS, or vice versa.

[0164] Such criteria may also or alternatively include periodic or aperiodic characteristics of the RS. For example, the WTRU may determine that RE muting may be used for P-CSI-RS and no RE muting may be used for A-CSI-RS, or vice versa.

[0165] Such criteria may also or instead include the modulation order of the PDSCH that may be used for scheduling.

[0166] Such criteria may also or instead include a coding rate or effective coding rate that may be used for the scheduled PDSCH.

[0167] Such criteria may also or instead include the number and / or rank of codewords.

[0168] Such criteria may also or instead include an indication which may be provided in the DCI.

[0169] The WTRU may be configured to monitor the EPDCCH for one or more DCIs that may be associated with at least one of PDSCH scheduling, PUSCH scheduling, and / or common control information. The terms "enhanced PDCCH," "EPDCCH," "MTCPDCCH," "MPDCCH," "narrowband PDCCH," and "NB-PDCCH" are used interchangeably herein. "EPDCCH" may refer to a downlink control channel that is monitored, decoded, received, and / or transmitted in the PDCCH region. In the event that the WTRU may be configured to monitor the EPDCCH, one or more REs in the EPDCCH resources that may be occupied by CSI-RS (e.g., A-CSI-RS, P-CSI-RS) may be muted. EPDCCH REs that may collide with CSI-RS may be muted.

[0170] It can be based on the available REs (n EPDCCH ) and / or for the PRB pairs configured for the EPDCCH resource set to determine the ECCE aggregation level set of the EPDCCH candidates in the EPDCCH search space. Such available REs may exclude REs that may be used by the CSI-RS in the subframe. In the case where the number of available REs may be greater than, or greater than or equal to, a threshold (e.g., a predetermined threshold, a pre-configured threshold), a first ECCE aggregation level set may be used and / or determined for the EPDCCH search space. A second ECCE aggregation level set may be used and / or determined for the EPDCCH search space, where the number of available REs may be less than, or less than or equal to, a threshold (e.g., a predetermined threshold, a pre-configured threshold).

[0171] REs that can be used for CSI-RS can be determined to be available REs based on one or more of the CSI-RS attributes. One or more REs that can be used for and / or occupied by P-CSI-RS can be determined to be unavailable (e.g., muted). One or more REs that can be used for A-CSI-RS can be determined to be available REs.

[0172] One or more REs that may be used for A-CSI-RS may be determined as available REs. The WTRU may consider such REs as muted REs when decoding one or more EPDCCH candidates.

[0173] One or more REs that may be used for P-CSI-RS may be determined as unavailable REs. The WTRU may consider such REs as muted REs when decoding one or more EPDCCH candidates.

[0174] A set of one or more ECCE aggregation levels may be determined based on the presence of P-CSI-RS. Such a set of EPDCCH aggregation levels may be determined independently of the presence of A-CSI-RS.

[0175] The number of EREGs per ECCE may be determined based on the presence of A-CSI-RS in a subframe. For example, when an A-CSI-RS may not exist in a subframe, N1 (e.g., 4) EREGs per ECCE may be used. For example, when an A-CSI-RS may exist in a subframe, N2 (e.g., 8) EREGs per ECCE may be used.

[0176] The number of EREGs per ECCE may be determined based on the number of REs in which A-CSI-RS exists and / or may be used for A-CSI-RS in a PRB in a subframe. The number of REs that may be used for A-CSI-RS in a PRB may be less than, or less than or equal to, a threshold (e.g., a predetermined threshold, a preconfigured threshold) (e.g., N THRESHOLD =16), N1 EREGs per ECCE may be used. Where the number of REs that may be used for A-CSI-RS in a PRB may be greater than, or greater than or equal to, a threshold (e.g., a predetermined threshold, a preconfigured threshold), N2 EREGs per ECCE may be used.

[0177] The number of REs that can be used for A-CSI-RS can include a count of REs used for one or more Type-1 A-CSI-RS or Type-2 A-CSI-RS (e.g., only for one or more Type-1 A-CSI-RS or Type-2 A-CSI-RS). The threshold (e.g., a predetermined threshold, a preconfigured threshold) can be based on the number of PRB pairs that can be configured for the EPDCCH resource set. The N1 value can differ from the N2 value based on at least one of the subframe type, CP length, and / or duplex mode (e.g., TDD or FDD).

[0178] EPDCCH RE muting can be used for REs that can be occupied by CSI-RS. Puncturing and / or rate matching for such muted REs can be determined based on the type of A-CSI-RS. For example, EPDCCH RE puncturing can be used for Type-1 A-CSI-RS, while EPDCCH RE rate matching can be used for Type-2 A-CSI-RS, or vice versa.

[0179] The puncturing and / or rate matching of such silent REs may also or alternatively be determined based on the periodic or aperiodic characteristics of the RS. For example, EPDCCH RE rate matching may be used for P-CSI-RS, while EPDCCH RE puncturing may be used for A-CSI-RS, or vice versa.

[0180] The puncturing and / or rate matching of such muted REs may also or alternatively be determined based on the EPDCCH search space type. For example, EPDCCH RE puncturing may be used for A-CSI-RS in the EPDCCH common search space, while EPDCCH RE rate matching may be used for A-CSI-RS in the EPDCCH WTRU-specific search space, or vice versa.

[0181] Puncturing and / or rate matching of such muted REs may also or alternatively be determined based on the ECCE aggregation level of the EPDCCH candidate.

[0182] The use of EPDCCH RE muting for EPDCCH REs that may be occupied by CSI-RS may be determined based on the type of A-CSI-RS. EPDCCH RE muting for EPDCCH REs that may be occupied by CSI-RS may be used for Type-1 A-CSI-RS, while no EPDCCH RE muting may be used for Type-2 A-CSI-RS, or vice versa. Alternatively or additionally, EPDCCH RE muting for EPDCCH REs that may be occupied by CSI-RS may be used based on the periodic or aperiodic characteristics of the RS. For example, EPDCCH RE muting may be used for P-CSI-RS, while no EPDCCH RE muting may be used for A-CSI-RS, or vice versa. Alternatively or additionally, EPDCCH RE muting for EPDCCH REs that may be occupied by CSI-RS may be used based on the EPDCCH search space type. For example, EPDCCH RE muting may be used for CSI-RS that may be in the EPDCCH common search space, while EPDCCH RE muting may not be used for CSI-RS that may be in the EPDCCH WTRU-specific search space, or vice versa. Alternatively or additionally, EPDCCH RE muting of EPDCCH REs that may be occupied by CSI-RS may be used based on the ECCE aggregation level of the EPDCCH candidate.

[0183] EPDCCH REs that may be used for A-CSI-RS may be considered unusable REs (e.g., muted REs). The A-CSI-RS and / or A-CSI-RS pattern used for EPDCCH RE muting may be indicated in a DCI that may be transmitted and / or monitored in the PDCCH common search space. The WTRU may determine the EPDCCH aggregation level set for the EPDCCH WTRU-specific search space in a subframe based on the presence or absence and / or pattern of A-CSI-RS that may be indicated in the DCI that may be received and / or monitored in the PDCCH common search space in the same subframe.

[0184] DCI may be sent and / or received in subframes (e.g., only in subframes) in which one or more A-CSI-RS may be present. Alternatively or additionally, DCI may be sent and / or received in all subframes regardless of whether A-CSI-RS is present. A bit field may be used to indicate the presence or absence of A-CSI-RS and / or one or more A-CSI-RS patterns. In the event that such a bit field may indicate that A-CSI-RS is not present in the subframe, the WTRU may determine that A-CSI-RS is not present in the subframe. Alternatively or additionally, the determination of the EPDCCH aggregation level set may be based on available REs, where the available REs may be determined based on the absence or presence of A-CSI-RS. In the event that the WTRU fails to receive DCI that may indicate the absence or presence of A-CSI-RS in the subframe, the WTRU may not monitor EPDCCH in the subframe.

[0185] The presence and / or transmission of one or more A-CSI-RS may be used to avoid collisions between the EPDCCH and the A-CSI-RS. Such A-CSI-RS presence and / or transmission may be limited to a subset of time and / or frequency resources. A subframe and / or radio frame may have a DCI that may indicate the presence of an A-CSI-RS. The WTRU may monitor the DCI for these subframes and / or radio frames. Such subframes and / or radio frames may be limited to a subset of subframes and / or radio frames in the system. Such a subset of subframes and / or radio frames may be configured via higher layer signaling.

[0186] Alternatively or additionally, subframes and / or radio frames that may have DCI that may be monitored by a WTRU may indicate the presence of A-CSI-RS. The subframes and / or radio frames monitored by such a WTRU may be determined based on one or more of a subframe number, a radio frame number (e.g., a system frame number (SFN)), a physical cell ID, and / or a WTRU-ID.

[0187] Alternatively or additionally, the WTRU may determine that A-CSI-RS may not be transmitted and / or located in one or more PRBs configured and / or used for EPDCCH, e.g., regardless of whether one or more A-CSI-RS may or may not be present in the subframe.

[0188] The WTRU-specific search space may be switched between the PDCCH and EPDCCH based on the presence of A-CSI-RS in a subframe. For example, a WTRU may be configured with an EPDCCH for a WTRU-specific search space and, if the WTRU may receive an indication of the presence of an A-CSI-RS in a subframe, the WTRU may monitor the PDCCH for the WTRU-specific search space in the subframe. The PDCCH WTRU-specific search space may be used as a fallback WTRU-specific search space. Such a fallback WTRU-specific search space may be used where one or more A-CSI-RS may collide with the EPDCCH WTRU-specific search space. Alternatively or additionally, the presence of an A-CSI-RS in a subframe may be indicated by a DCI. Such DCI may be sent and / or monitored in the PDCCH common search space. Alternatively or additionally, the presence of an A-CSI-RS in a subframe may be indicated in a previous subframe. Alternatively or additionally, the WTRU may not monitor one or more EPDCCH candidates in a subframe where such one or more EPDCCH candidates may collide with one or more A-CSI-RS that may be present in the subframe.

[0189] The antenna port set for the CSI-RS configuration may be indicated in the transmission of the PRB subset. For example, the antenna port set for the CSI-RS configuration in the PRB (e.g., the current antenna port set) may be determined based on the PRB index. Alternatively or additionally, the antenna port set for the first CSI-RS configuration (e.g., the current antenna port set) may be present in one or more PRBs that may have an even number of PRB indices or be associated with an even number of PRB indices, while the antenna port set for the second CSI-RS configuration (e.g., the current antenna port set) may be present in one or more PRBs that may have an odd number of PRB indices or be associated with an odd number of PRB indices, or vice versa.

[0190] A WTRU may receive an indication of a subset of one or more PRBs that may contain an associated CSI-RS. For example, a first set of PRBs (e.g., a set that may have an even number of PRB indices) may be indicated for a first WTRU, while a second set of PRBs (e.g., a set that may have an odd number of PRB indices) may be indicated for a second, different WTRU. Such an indication may be signaled as part of one or more CSI-RS configuration parameters. Alternatively or additionally, such an indication may be signaled in an associated DCI for A-CSI-RS triggering.

[0191] CSI-RS PRB level zeroing may be used, where the antenna port set for a CSI-RS configuration may be transmitted in a subset of one or more PRBs. The use of such zeroing may be determined based on the number of antenna ports. For example, CSI-RS PRB level zeroing may be used where the number of antenna ports for CSI-RS may be greater than, or greater than or equal to, a threshold (e.g., a predetermined threshold, a preconfigured threshold) (e.g., 16). The antenna port set for a CSI-RS configuration may be used interchangeably with a plurality of antenna ports.

[0192] The PRB index for which CSI-RS PRB level zeroing may be used may be determined based on the subframe and / or radio frame number. Alternatively or additionally, the PRB index for which CSI-RS PRB level zeroing may be used may be determined based on the CSI-RS PRB level zeroing, which may be determined based on the WTRU-ID (e.g., C-RNTI). Alternatively or additionally, the PRB index for which CSI-RS PRB level zeroing may be used may be determined based on the P-CSI-RS and / or A-CSI-RS.

[0193] A set of one or more PRBs associated with CSI-RS transmission may be determined based on one or more of the number of antenna ports configured for CSI-RS, one or more types of CSI-RS (e.g., P-CSI-RS, A-CSI-RS), one or more system parameters (e.g., subframe number, radio frame number, physical cell ID), and / or one or more WTRU-specific parameters (e.g., WTRU-ID). The set of PRBs so determined may include all PRBs in a subframe or a subset of the PRBs in a subframe.

[0194] One or more downlink control signals may be used for A-CSI-RS. For example, two control signal indications (e.g., DCI) may be used for A-CSI-RS. A first DCI may be used to indicate one or more active A-CSI-RS patterns (e.g., active A-CSI-RS sets). A second DCI may be used to indicate an active A-CSI-RS pattern that may be used for CSI measurement. An active A-CSI-RS set may include one or more A-CSI-RS configurations that may be active and / or present in an associated time window and / or position (e.g., subframe). An active A-CSI-RS set may be used interchangeably as a common A-CSI-RS set.

[0195] The active A-CSI-RS set may be a subset of an A-CSI-RS pattern that may be configured by higher layer signaling. Alternatively or additionally, the WTRU may determine that one or more A-CSI-RS patterns in the active A-CSI-RS set may be present in an associated time location (e.g., a subframe). Alternatively or additionally, the WTRU may monitor, receive, and / or attempt to decode a first DCI that may carry one or more active A-CSI-RS patterns. This operation may be performed regardless of whether such a WTRU may be configured for A-CSI-RS-based A-CSI reporting. Alternatively or additionally, the WTRU may use active A-CSI-RS set information, wherein such a WTRU may receive, attempt to decode, and / or schedule for downlink transmissions (e.g., PDSCH, EPDCCH) in an associated time window and / or location (e.g., a PDSCH region in a subframe). Alternatively or additionally, RE muting may be used for downlink transmissions (e.g., PDSCH, EPDCCH) on REs used and / or occupied by the active A-CSI-RS set in a subframe. Alternatively or additionally, the associated time window for one or more active A-CSI-RS patterns may be determined based on activation and / or deactivation of the active A-CSI-RS pattern. For example, an active A-CSI-RS pattern may be activated in subframe n and deactivated in another subframe n+k.

[0196] One or more A-CSI-RS patterns in the active A-CSI-RS set may be indicated in a DCI (e.g., a second DCI that may be used to indicate an active A-CSI-RS pattern for CSI measurement as described herein) and referred to as a dedicated A-CSI-RS set. The terms "dedicated A-CSI-RS set" and "measurement A-CSI-RS set" are used interchangeably herein.

[0197] A dedicated A-CSI-RS set may be one or more WTRU-specific A-CSI-RS patterns that may be used for CSI measurement. Alternatively or additionally, a dedicated A-CSI-RS set may be used for CSI reporting. Alternatively or additionally, some configuration information (e.g., transmit power, quasi-configuration, number of antenna ports) of the dedicated A-CSI-RS set may be configured by higher layer signaling, while some or all of the remaining configuration information (e.g., CSI-RS reuse pattern) may be indicated in another DCI (e.g., a second DCI).

[0198] DCI for active A-CSI-RS set information (e.g., first DCI) may be transmitted and / or monitored in a common search space (CSS) such as a PDCCH CSS and / or an EPDCCH CSS. Such DCI may be monitored by a WTRU in the PDCCH CSS and / or the EPDCCH CSS, where the PDCCH CSS and / or the EPDCCH CSS used for the DCI may be different from the PDCCH CSS and / or the EPDCCH CSS used for other DCI. Such other DCI may carry multicast and / or broadcast signals. For example, control channel elements such as CCEs and / or ECCEs (herein referred to as (E)CCEs, #0 to #15) may be used for the PDCCH CSS and / or EPDCCH CSS for such other DCI (e.g., DCI with P-RNTI, SI-RNTI) that may carry multicast and / or broadcast signals. Control channel elements (E)CCEs #16 to #32 may be used for the PDCCH CSS and / or EPDCCH CSS for such DCI. The DCI may include the active A-CSI-RS set.

[0199] Such a DCI (e.g., a first DCI) may be scrambled with a common RNTI. Alternatively or additionally, such a DCI may include a bit field that may indicate the active A-CSI-RS set. Such a bit field may be a bit field that may be associated with one or more N A-CSI-RS A-CSI-RS configuration associated bitmap. For example, one or more N A-CSI-RS In the case of A-CSI-RS configuration, N A-CSI-RS A bit may be used for a bit field and / or may indicate active and / or inactive A-CSI-RS configurations. Alternatively or additionally, one or more groups of one or more active A-CSI-RS sets may be defined, predefined, and / or configured. Such one or more groups may be indicated in such a DCI (e.g., a first DCI).

[0200] A different DCI (e.g., a second DCI, as opposed to the first DCI described above) may be associated with dedicated A-CSI-RS set information that may be sent and / or monitored in a WTRU-specific search space. Such a different DCI (e.g., a second DCI) may be used in an uplink grant (e.g., DCI format 0 / 4), where a bit field may be used to indicate a dedicated A-CSI-RS set that may be used in the uplink grant. Alternatively or additionally, a flag bit may be included and / or used in such a DCI (e.g., a second DCI) to indicate whether a bit field associated with the dedicated A-CSI-RS set information may be included in the DCI. In the case where the flag bit may be set to TRUE, the WTRU may use one or more A-CSI-RSs indicated by the dedicated A-CSI-RS set information for A-CSI reporting. In the case where the flag bit may be set to FALSE, the WTRU may use P-CSI-RSs for A-CSI reporting, where such P-CSI-RSs may be located in the same subframe or in adjacent subframes.

[0201] One or more A-CSI-RS patterns in the active A-CSI-RS set that may not be indicated in the dedicated A-CSI-RS set may be considered as type-2 A-CSI-RS, while the A-CSI-RS patterns that may be indicated in the active A-CSI-RS set may be considered as type-1 A-CSI-RS.

[0202] The active A-CSI-RS set may be configured via higher layer signaling (e.g., RRC, broadcast). The dedicated A-CSI-RS set may be indicated in the DCI. One or more A-CSI-RS patterns may be configured as the active A-CSI-RS set via higher layer signaling, and one or more A-CSI-RS patterns within the active A-CSI-RS set may be indicated in the DCI as the dedicated A-CSI-RS set.

[0203] The active A-CSI-RS set may be configured via higher layer signaling and may be used to perform RE muting for downlink transmissions (e.g., PDSCH, EPDCCH, PBCH, PMCH) in a subframe where the WTRU receives one or more of an A-CSI report request indication, a dedicated A-CSI-RS set indication, and / or an indication in DCI. Such an indication in the DCI may be used to perform RE muting for downlink transmissions of REs that may be used for active A-CSI-RS. Such an indication may be sent in the DCI that may be associated with PDSCH scheduling.

[0204] RE muting for downlink transmission of one or more REs of one or more active A-CSI-RS sets may be used at one or more times (e.g., one or more predetermined times, one or more preconfigured times) and / or at one or more frequency locations (e.g., one or more predetermined frequency locations, one or more preconfigured frequency locations). Such times and / or frequency locations may be a subset of subframes that may be configured by higher layer signaling. Alternatively or additionally, such times and / or frequency locations may be determined based on at least one of a subframe number, a physical cell ID, a radio frame number (e.g., SFN), and / or a WTRU-ID (e.g., C-RNTI).

[0205] A DCI (e.g., a first DCI, which may or may not be the same first DCI as described elsewhere herein) may carry active A-CSI-RS set information. Another DCI (e.g., a second DCI, which may or may not be the same second DCI as described elsewhere herein) may carry dedicated A-CSI-RS set information. The WTRU may receive, attempt to decode, and / or monitor such DCI (e.g., the first DCI) carrying active A-CSI-RS set information and such DCI (e.g., the second DCI) carrying dedicated A-CSI-RS set information to obtain one or more type-1 A-CSI-RS configurations and / or one or more type-2 A-CSI-RS configurations. For example, the dedicated A-CSI-RS set may be considered a type-1 A-CSI-RS configuration, while one or more remaining other A-CSI-RSs in the active A-CSI-RS set (which may not be indicated in the dedicated A-CSI-RS set) may be considered a type-2 A-CSI-RS.

[0206] One or more fallback A-CSI-RS set configurations may be determined and / or used. One or more such fallback A-CSI-RS sets may be one or more A-CSI-RS configuration sets that may be used for RE muting for downlink transmissions. One or more such fallback A-CSI-RS sets may be the same as one or more A-CSI-RS pattern sets that may be configured via higher layer signaling. A WTRU may use such one or more fallback A-CSI-RS sets for RE muting for downlink transmissions, where such a WTRU may have failed to receive a DCI (e.g., a first DCI) (e.g., which may include active A-CSI-RS set information). For example, such a WTRU may have received another DCI (e.g., a second DCI) (e.g., which may include dedicated A-CSI-RS set information) in a subframe and may use one or more fallback A-CSI-RS sets for RE muting for downlink transmissions.

[0207] A WTRU may determine not to receive a downlink signal in a subframe in which such a WTRU failed to receive a DCI (e.g., a first DCI) (e.g., which may include active A-CSI-RS set information). For example, such a WTRU may have received another DCI (e.g., a second DCI) which may have included a dedicated A-CSI-RS set, for example. Such a WTRU may also receive another DCI for PDSCH scheduling in the same subframe while having missed a DCI (e.g., the first DCI) which may have included active A-CSI-RS set information. Such a WTRU may determine not to decode the PDSCH and / or may measure A-CSI from a dedicated A-CSI-RS set (e.g., as received in the second DCI). Such a WTRU may not buffer the PDSCH for hybrid automatic repeat request (HARQ) operation (e.g., because the soft buffer may be corrupted). Alternatively or additionally, such a WTRU may send a discontinuous transmission (DTX) for a corresponding PDSCH, for example, which may not be decoded by the WTRU based on the loss of a DCI (e.g., the first DCI) that may have included active A-CSI-RS set information.

[0208] A WTRU may receive an indication that may instruct or otherwise cause the WTRU to report A-CSI in subframe n. The A-CSI-RS used for A-CSI measurement may be reported in subframe m. Such a WTRU may report the requested A-CSI in subframe n+k via an uplink channel.

[0209] The A-CSI reporting timing (e.g., n+k) may be determined based on one or more associated CSI-RS attributes. The presence of an A-CSI-RS for A-CSI reporting may not be known until the WTRU may receive an indication of its presence. This may result in increased processing time for performing channel measurements based on the A-CSI-RS. k=4 may be used, where the A-CSI report may be associated with the P-CSI-RS. k>4 may be used, where the A-CSI report may be associated with the A-CSI-RS.

[0210] The A-CSI reporting timing (e.g., n+k) may be determined based on one or more associated CSI-RS attributes. Such reporting timing (e.g., n+k) may be determined based on one or more associated CSI-RS types of the triggered A-CSI. In the case where the associated CSI-RS type may be A-CSI-RS, the reporting timing may be determined based on the temporal position of A-CSI-RSm. In the case where m may be the same as n, the reporting timing n+k may be the same for P-CSI-RS and A-CSI-RS. In the case where the temporal position of the A-CSI-RS may be m=n+t, the reporting timing may be determined as n+t+k.

[0211] The A-CSI reporting timing may be determined based on the associated A-CSI-RS configuration. For example, such reporting timing may be determined based on the A-CSI-RS configuration index. Figure 5 As shown in the exemplary A-CSI-RS configuration (or reuse pattern) 500 for 8Tx shown in FIG, five A-CSI-RS configurations (e.g., Figure 5 The time position of the A-CSI-RS configuration can be used to determine the reporting time. n+k can be used as the reporting timing, for example, where the A-CSI-RS configuration ( Figure 5 Such an exemplary A-CSI-RS configuration 501 shown in FIG. 5 may be indicated as the associated A-CSI-RS for A-CSI reporting. Alternatively or additionally, n+k+1 may be used as the reporting timing, e.g., where the associated A-CSI-RS configuration (e.g., Figure 5 The exemplary A-CSI-RS configuration 502, A-CSI-RS configuration 503 and / or A-CSI-RS configuration 501 shown may be indicated as the associated A-CSI-RS for A-CSI reporting. Alternatively or additionally, n+k+2 may be used as the reporting timing, e.g., where the associated A-CSI-RS configuration (e.g., Figure 5 The illustrated exemplary A-CSI-RS configuration 505) may be indicated as associated A-CSI-RS for A-CSI reporting.

[0212] The reporting time of A-CSI (e.g., n+k) may be used regardless of the associated CSI-RS attributes. The CSI measurement search space may be limited based on such associated CSI-RS attributes for A-CSI reporting. The CSI measurement search space may include and / or indicate one or more CSI types that may be reported, a range for each of the one or more CSI types, a parameter for each of the one or more CSI types, and / or a value for one or more CSI types. One or more subsets or all of these values ​​and / or indicators may be associated with each other. One or more of multiple CSI types to be reported, multiple ranges for CSI types, multiple parameters for CSI types, and multiple values ​​for CSI types may be included and / or indicated in the CSI measurement search space.

[0213] The CSI type may include one or more of wideband CQI, subband CQI, RI, wideband PMI, subband PMI, precoding type indication (PTI), CSI-RS resource indication (CRI), and / or subband index. The range of CSI types that may be associated with CQI (e.g., wideband CQI, subband CQI) may be predefined or predetermined as a signal-to-noise ratio (SNR) range (e.g., a range from 0 to 15), where such an SNR range may be defined at / at the modulation and coding scheme (MCS) level. The range of CSI types that may be associated with PMI and / or RI (e.g., wideband CQI, subband CQI) may be determined based on the number of antenna ports and / or transmission mode and / or transmission scheme that may be configured. Parameters of CSI types that may be associated with subband reporting (e.g., subband CQI, subband PMI) may include the subband size used for such reporting.

[0214] The CSI measurement search space can be restricted, where the associated CSI-RS can be A-CSI-RS. For example, RI can be limited to a subset of candidates. Such RI can be searched in the full candidate of {1,2,3,4}, where A-CSI can be triggered based on P-CSI-RS, while RI can be searched in the restricted candidate of {1,2}, where A-CSI can be triggered based on A-CSI-RS. The restricted candidates for RI can be determined based on the RI report value (e.g., the latest RI report value). The restricted candidates for RI can be configured through higher layer signaling. The restricted candidates for RI can be indicated in the associated DCI that can trigger A-CSI reporting. For example, such restricted candidates for RI can be a single candidate (e.g., {2}). The maximum RI value can be determined based on one or more CSI-RS types (e.g., P-CSI-RS, A-CSI-RS).

[0215] The number of CSI processes may be limited. For example, Nc CSI processes may be configured via higher layer signaling. The eNodeB may trigger A-CSI reporting for such Nc CSI processes, where one or more P-CSI-RSs may be used. When one or more A-CSI-RSs may be used, a subset of the Nc CSI processes may be used for A-CSI reporting. A single CSI process may be used (e.g., only used) for A-CSI reporting, where A-CSI may be measured from the A-CSI-RSs. The CSI process index for A-CSI reporting may be indicated in the associated DCI that may be used for A-CSI reporting.

[0216] The PMI can be restricted to a subset of candidates. For example, the PMI candidates for A-CSI reporting with P-CSI-RS can be determined based on a codebook subset restriction that can be configured via higher layer signaling. The PMI candidates for A-CSI reporting with A-CSI-RS can be based on a subset of PMI candidates that can be determined for A-CSI reporting with P-CSI-RS. For example, two levels of codebook subset restriction can be used for A-CSI reporting with A-CSI-RS. The first codebook subset restriction can be used for P-CSI-RS and A-CSI-RS, while the second codebook subset restriction can be used for A-CSI-RS.

[0217] In the case where the PMI may be restricted to a candidate subset, the first codebook subset restriction may be a superset of the second codebook subset restriction. Alternatively or additionally, the first codebook subset restriction may be configured via higher layer signaling. Alternatively or additionally, the second codebook subset restriction may be configured via higher layer signaling (e.g., separate signaling from the signaling used to signal the first codebook subset restriction) that may be used for the WTRU that may be configured with an A-CSI-RS. Alternatively or additionally, the second codebook subset restriction may be dynamically indicated from an associated DCI that may trigger an A-CSI report with an A-CSI-RS.

[0218] The PMI may be indicated in the associated DCI that may trigger an A-CSI report with an A-CSI-RS. For example, a specific PMI may be indicated with the A-CSI report. The WTRU may use the indicated specific PMI to search for other CSI reporting indices (e.g., CQI, RI).

[0219] The subband size for subband CQI and / or subband PMI reporting may be determined based on one or more CSI-RS types (e.g., P-CSI-RS, A-CSI-RS). For example, a first subband size may be used for subband CQI and / or subband PMI reporting, where the CSI reporting may be based on P-CSI-RS. For example, a second subband size may be used for subband CQI and / or subband PMI reporting, where the CSI reporting may be based on A-CSI-RS. Such a first subband size may be narrower than the second subband size, or vice versa. Such a second subband size may be a multiple of such a first subband size. Alternatively or additionally, such a second subband size may be indicated in a DCI that may trigger an A-CSI report with an A-CSI-RS.

[0220] One or more subbands that can be used for CSI reporting, where A-CSI reporting can be triggered based on A-CSI-RS, can be limited. For example, Ns subbands can be used for A-CSI reporting, where P-CSI-RS can be used for CSI measurement, and Na subbands can be used for A-CSI reporting, where A-CSI-RS can be used for CSI measurement. Na can be less than Ns. Ns can be determined based on the system bandwidth. Na can be configured and / or predetermined through higher layer signaling. Ns can be indicated in the DCI that can trigger A-CSI reporting with A-CSI-RS. The subband (e.g., a specific subband) can be indicated in the DCI that can trigger A-CSI reporting with A-CSI-RS.

[0221] Although features and elements are described above in particular combinations, it will be understood by one of ordinary skill in the art that each feature or element can be used alone or in any combination with the other features and elements. In addition, the methods described herein may be implemented in a computer program, software, or firmware incorporated into a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic 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, cache memory, semiconductor memory devices, magnetic media (e.g., internal hard disks and removable disks), magneto-optical media, and optical media (e.g., CD-ROM disks and digital versatile disks (DVDs)). A processor associated with the software may be used to implement a radio frequency transceiver for a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A wireless transmit / receive unit (WTRU), the WTRU comprising: A processor, wherein the processor is configured to: receiving configuration information for a channel state information reference signal (CSI-RS), wherein the configuration information indicates one or more CSI-RS resources; receiving scheduling information for receiving a physical downlink shared channel (PDSCH) transmission, wherein the scheduling information indicates PDSCH resources, wherein the PDSCH resources include a first number of resources and a second number of resources, and wherein the first number of resources overlaps with at least CSI-RS resources from the one or more CSI-RS resources; as well as receiving the PDSCH transmission, wherein: On the condition that the CSI-RS is an aperiodic non-zero power CSI-RS NZP-CSI-RS, the processor is configured to use the first number of resources and the second number of resources, or to puncture the first number of resources and use the second number of resources; as well as On the condition that the CSI-RS is a periodic NZP-CSI-RS, the processor is configured to use the second amount of resources.

2. The WTRU of claim 1 , wherein the processor is configured to receive the PDSCH transmission conditional on the CSI-RS being the aperiodic NZP-CSI-RS, comprising: The processor is configured to receive the PDSCH transmission using at least a PDSCH modulation symbol, wherein the PDSCH modulation symbol is mapped to a PDSCH resource from the PDSCH resources.

3. The WTRU of claim 1 , wherein the processor is configured to receive the PDSCH transmission comprising: The processor is configured to receive the PDSCH transmission under the condition that the CSI-RS is a periodic zero power CSI-RS ZP-CSI-RS or an aperiodic ZP-CSI-RS.

4. The WTRU of claim 1 , wherein the processor is configured to receive the PDSCH transmission conditional on the CSI-RS being the periodic NZP-CSI-RS, comprising: The processor is configured to receive the PDSCH transmission using at least a PDSCH modulation symbol, wherein the PDSCH modulation symbol is mapped to a PDSCH resource from the second number of resources.

5. The WTRU of claim 1 , wherein the PDSCH resources comprise resource elements.

6. The WTRU of claim 1 , wherein the CSI-RS resources comprise resource elements.

7. A method performed by a wireless transmit / receive unit (WTRU), the method comprising: receiving configuration information for a channel state information reference signal (CSI-RS), wherein the configuration information indicates one or more CSI-RS resources; receiving scheduling information for receiving a physical downlink shared channel (PDSCH) transmission, wherein the scheduling information indicates PDSCH resources, wherein the PDSCH resources include a first number of resources and a second number of resources, and wherein the first number of resources overlaps with at least CSI-RS resources from the one or more CSI-RS resources; and receiving the PDSCH transmission, wherein: On the condition that the CSI-RS is an aperiodic non-zero power CSI-RS (NZP-CSI-RS), using the first number of resources and the second number of resources, or puncturing the first number of resources and using the second number of resources; and On the condition that the CSI-RS is a periodic NZP-CSI-RS, the second number of resources is used.

8. The method of claim 7, wherein receiving the PDSCH transmission under the condition that the CSI-RS is the aperiodic NZP-CSI-RS comprises: The PDSCH transmission is received using at least a PDSCH modulation symbol, wherein the PDSCH modulation symbol is mapped to a PDSCH resource from the PDSCH resources.

9. The method according to claim 8, wherein Receiving the PDSCH transmission includes receiving the PDSCH transmission under the condition that the CSI-RS is a periodic zero-power CSI-RS ZP-CSI-RS or an aperiodic ZP-CSI-RS.

10. The method of claim 8, wherein receiving the PDSCH transmission under the condition that the CSI-RS is the periodic NZP-CSI-RS comprises: The PDSCH transmission is received using at least a PDSCH modulation symbol, wherein the PDSCH modulation symbol is mapped to a PDSCH resource from the second number of resources.

11. The method according to claim 8, wherein The PDSCH resource includes resource elements.

12. The method according to claim 8, wherein The CSI-RS resource includes a resource unit.

13. A base station, comprising: A processor, wherein the processor is configured to: Sending configuration information for a channel state information reference signal (CSI-RS), wherein the configuration information indicates one or more CSI-RS resources; sending scheduling information for receiving a physical downlink shared channel (PDSCH) transmission, wherein the scheduling information indicates PDSCH resources, wherein the PDSCH resources include a first number of resources and a second number of resources, and wherein the first number of resources overlaps with at least CSI-RS resources from the one or more CSI-RS resources; and Sending the PDSCH transmission, wherein: On the condition that the CSI-RS is an aperiodic non-zero power CSI-RS (NZP-CSI-RS), the processor is configured to use the first number of resources and the second number of resources, or to puncture the first number of resources and use the second number of resources; and On the condition that the CSI-RS is a periodic NZP-CSI-RS, the processor is configured to use the second amount of resources.

14. The base station according to claim 13, wherein the processor is configured to send the PDSCH transmission under the condition that the CSI-RS is the aperiodic NZP-CSI-RS, comprising: The processor is configured to send the PDSCH transmission using at least a PDSCH modulation symbol, wherein the PDSCH modulation symbol is mapped to a PDSCH resource from the PDSCH resources.

15. The base station of claim 13 , wherein the processor is configured to send the PDSCH transmission under the condition that the CSI-RS is the periodic NZP-CSI-RS, comprising: The processor is configured to send the PDSCH transmission using at least a PDSCH modulation symbol, wherein the PDSCH modulation symbol is mapped to a PDSCH resource from the second number of resources.

16. The base station of claim 13, wherein the processor is configured to send the PDSCH transmission, comprising: The processor is configured to send the PDSCH transmission under the condition that the CSI-RS is a periodic zero power CSI-RS ZP-CSI-RS or an aperiodic ZP-CSI-RS. The base station of claim 13 , wherein the PDSCH resources comprise resource elements. The base station according to claim 13 , wherein the CSI-RS resource comprises a resource element.

Images