Broadcast Channel Transmission and Demodulation

Abstract

To provide a method and an apparatus for demodulating an NR-PBCH signal.SOLUTION: A method may comprise receiving a primary SS and an SSS. The received SSS signal may be used as a reference signal to detect demodulation reference signals of an NR-PBCH. These demodulation reference signals may be interleaved with data on the NR-PBCH. In one method, the NR-PBCH DMRS are associated with an SSB index in an effort to improve randomization in the synchronization process. The NR-PBCH payload may be demodulated using the PSS and / or SSS and the DMRS. In one embodiment, the NR-PBCH DMRS may mapped to DMRS REs on a frequency first and time second mapping basis.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 62 / 454,621, filed February 3, 2017, U.S. Provisional Patent Application No. 62 / 500,702, filed May 3, 2017, U.S. Provisional Patent Application No. 62 / 519,751, filed June 14, 2017, and U.S. Provisional Patent Application No. 62 / 543,155, filed August 9, 2017, the contents of each of which are incorporated herein by reference. [Background technology]

[0002] Legacy cellular systems, such as the fourth generation Long Term Evolution (LTE), employ a relatively simple synchronization procedure. For example, in LTE, the physical broadcast channel (PBCH) always uses the same bandwidth as both the primary synchronization signal (PSS) and the secondary synchronization signal (SSS). Therefore, in legacy LTE systems, both are allocated in the same six resource blocks (RBs) in the frequency domain. Due to frequency correlation, the receiver in a wireless transmit / receive unit (WTRU) can use both the PSS and SSS as reference signals for PBCH demodulation.

[0003] However, in New Radio (NR), the NR-PBCH may consume more bandwidth and may be allocated more RBs than NR-SSS. In NR, the PBCH may occupy 24 RBs compared to 12 RBs for SSS. Therefore, in NR, the SSS is no longer a good reference signal for PBCH demodulation due to the frequency disparity.

[0004] Furthermore, in LTE, the PBCH may use a common reference signal (CRS) for PBCH demodulation when one exists. However, in NR, CRS does not exist due to NR's attempt to minimize always-on signals. Therefore, CRS is no longer suitable as a reference signal for NR-PBCH demodulation. For improved performance of NR-PBCH demodulation, accurate channel estimation may be required, especially when one-shot detection is considered. Therefore, a new reference signal (RS) design for accurate and efficient NR-PBCH demodulation may be adopted in the new NR-PBCH / NR-SS structure. Summary of the Invention

[0005] A method and apparatus for demodulating a New Radio Personal Broadcast Channel (NR-PBCH) signal is disclosed. The method can include receiving a primary synchronization signal (PSS) and a secondary synchronization signal (SSS). The received SSS signals can be used as reference signals for detecting a reference signal of the NR-PBCH. These demodulation reference signals can be interleaved with data on the NR-PBCH. In one method, the NR-PBCH demodulation reference signal (DMRS) is associated with a synchronization signal block (SSB) index to improve randomization in the synchronization process. [Brief explanation of the drawings]

[0006] A more detailed understanding may be had from the following description, given by way of example in conjunction with the accompanying drawings, in which like reference numerals refer to similar elements and in which: [Figure 1A] FIG. 1 is a system diagram illustrating an example communication system in which one or more disclosed embodiments may be implemented. [Figure 1B] 1B is a system diagram illustrating an example wireless transmit / receive unit (WTRU) that may be used within the communications system shown in FIG. 1A, according to an embodiment. [Figure 1C] 1B is a system diagram illustrating an example radio access network (RAN) and an example core network (CN) that may be used within the communication system shown in FIG. 1A, according to an embodiment. [Figure 1D] 1B is a system diagram illustrating another exemplary RAN and another exemplary CN that may be used within the communication system shown in FIG. 1A, according to an embodiment. [Figure 2] FIG. 1 illustrates an example of a repeated New Radio (NR) physical broadcast channel (NR-PBCH) multiplexing with an NR primary synchronization channel (SS) (NR-PSS) and an NR secondary synchronization channel (NR-SSS). [Figure 3] FIG. 10 illustrates an example of an NR-PBCH multiplexed with an NR-PSS and an NR-SSS with repeated NR-SS. [Figure 4] FIG. 1 is a diagram illustrating an example of NR-PBCH dedicated demodulation reference signal design 1 using one antenna port. [Figure 5] FIG. 10 is a diagram illustrating an example of NR-PBCH dedicated demodulation reference signal design 3 using two antenna ports. [Figure 6] FIG. 1 illustrates an exemplary NR-PBCH hybrid dedicated demodulation reference signal. [Figure 7] FIG. 10 illustrates an example of a non-uniform density NR-PBCH dedicated demodulation reference signal. [Figure 8] FIG. 1 illustrates an example of non-uniform demodulation reference signal (DMRS) density depending on PSS / SSS bandwidth. [Figure 9] FIG. 1 illustrates an example of configurable NR-PBCH demodulation. [Figure 10A] FIG. 1 is a circuit diagram of a seven-stage M-sequence shifter. [Figure 10B] FIG. 1 is a circuit diagram of a six-stage M-sequence shifter. [Figure 11] 1 is a flowchart of a procedure for receiver processing and information detection. [Figure 12] FIG. 1 illustrates an example of an initial access procedure and NR-PBCH demodulation assisted or aided by a QCL indicator. [Figure 13] A diagram showing an example of using SS blocks associated with different precoders. [Figure 14]A diagram showing an example of using SS blocks associated with different precoders that are shifted on different PBCH messages. [Figure 15] FIG. 1 is a diagram of an exemplary combination of analog beamforming and two-port cyclic delay diversity (CDD) for diversity. [Figure 16] FIG. 1 is a diagram of an example combination of digital and analog beamforming in the time domain. [Figure 17] FIG. 1 is a diagram of an example combination of digital and analog beamforming in the time and frequency domains. [Figure 18] FIG. 1 is a diagram of an example combination of analog beamforming and two-port space-frequency block coding (SFBC) for diversity. [Figure 19] FIG. 1 illustrates an exemplary transmission point (TRP) transmission structure for initial access. [Figure 20] FIG. 1 illustrates an exemplary single-stage exhaustive search beam sweep procedure. [Figure 21] FIG. 10 illustrates an example of a multi-stage WTRU hierarchical beam sweeping procedure. [Figure 22] A diagram showing an example of a multi-stage TRP and TRP / WTRU hierarchical beam sweeping procedure. [Figure 23] A diagram showing an example of a multi-stage TRP / WTRU hierarchical TRP selective beam sweeping procedure. [Figure 24] 10A-10C are diagrams of signal-to-interference-and-noise-ratio (SINR) performance results for various beam sweeping procedures. [Figure 25] FIG. 10 illustrates an example of an alternative TRP transmission structure for initial access. [Figure 26] FIG. 10 illustrates an example of an alternative single-stage exhaustive search beam sweep procedure. [Figure 27] FIG. 1 illustrates a single-stage multiple radio frequency (multi-RF) chain TRP beam sweeping procedure. [Figure 28] FIG. 1 illustrates an example of simple bit pattern frequency repetition. [Figure 29]FIG. 10 is another exemplary diagram of swapped repetition of bit pattern frequencies. [Figure 30] FIG. 10 illustrates an example of combined time and frequency swapped repetitions. [Figure 31] FIG. 10 illustrates a second example of combined time and frequency swapped repetition. [Figure 32] FIG. 1 shows an example of a length-62 sequence with repetition in frequency. [Figure 33] FIG. 10 illustrates an example of a two-sequence NR-PBCH DMRS distribution in a comb pattern. [Figure 34] FIG. 1 illustrates an example of DMRS and SBTI labels using cyclic shifting. [Figure 35] FIG. 10 shows an example of DMRS and SBTI signatures using cyclic shifts in a comb pattern. [Figure 36] Table 1 is a sequence of rows representing different cyclic shifts used to indicate SBTI. DETAILED DESCRIPTION OF THE INVENTION

[0007] 1A illustrates 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, broadcasts, and the like, to multiple wireless users. The communication system 100 may enable the multiple wireless users to access such content through the sharing of system resources, including wireless bandwidth. For example, the communication system 100 may utilize 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-tailed unique word DFT spread OFDM (ZT UW DTS-s OFDM), unique word OFDM (UW-OFDM), resource block-filtered OFDM, and filter bank multicarrier (FBMC).

[0008] 1A, communications system 100 may include wireless transmit / receive units (WTRUs) 102a, 102b, 102c, 102d, RANs 104 / 113, CNs 106 / 115, public switched telephone network (PSTN) 108, the Internet 110, and other networks 112, although it will be understood that the disclosed embodiments contemplate any number of WTRUs, base stations, networks, and / or network elements. Each of WTRUs 102a, 102b, 102c, 102d may be any type of device configured to operate and / or communicate in a wireless environment. For example, the WTRUs 102a, 102b, 102c, 102d, which may all be referred to as “base stations” and / or “STAs,” may be configured to transmit and / or receive wireless signals, and may include user equipment (UE), mobile stations, fixed or mobile subscriber units, subscription-based units, pagers, cellular phones, personal digital assistants (PDAs), smartphones, laptops, netbooks, personal computers, wireless sensors, hotspot or Mi-Fi devices, Internet of things (IoT) devices, watches or other wearables, head-mounted displays (HMDs), vehicles, drones, medical devices and applications (e.g., remote surgery), industrial devices and applications (e.g., robots and / or other wireless devices operating in the context of industrial and / or automated processing chains), consumer electronics devices, and devices operating commercial and / or industrial wireless networks. Any of the WTRUs 102a, 102b, 102c, and 102d may be referred to interchangeably as UEs.

[0009] The communications 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 communications networks, such as the CN 106 / 115, the Internet 110, and / or other networks 112. For example, the base stations 114a, 114b may be a base transceiver station (BTS), a Node-B, an eNodeB, a Home Node B, a Home eNodeB, a gNB, an NR NodeB, a site controller, an access point (AP), a wireless router, etc. Although the base stations 114a, 114b are each shown as a single element, it will be understood that the base stations 114a, 114b may include any number of interconnected base stations and / or network elements.

[0010] The base station 114a may be part of the 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), relay nodes, etc. The base station 114a and / or base station 114b may be configured to transmit and / or receive wireless signals on one or more carrier frequencies, sometimes referred to as a cell (not shown). These frequencies may be in the licensed spectrum, the unlicensed spectrum, or a combination of the licensed and unlicensed spectrum. A cell may provide coverage for wireless services in a particular 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 the base station 114a may be divided into three sectors. Thus, in one embodiment, the base station 114a may include three transceivers, i.e., one transceiver for each sector of the cell. In an embodiment, the base station 114a may employ multiple-input multiple-output (MIMO) technology and thus may utilize multiple transceivers for each sector of the cell. For example, beamforming may be used to transmit and / or receive signals in desired spatial directions.

[0011] 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).

[0012] More specifically, as noted 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, etc. For example, the base station 114a and the WTRUs 102a, 102b, 102c in the RAN 104 / 113 may implement a radio technology such as Universal Mobile Telecommunications System (UMTS) Terrestrial Radio Access (UTRA), which may establish the air interface 115 / 116 / 117 using Wideband CDMA (WCDMA). WCDMA may include communication protocols such as High Speed ​​Packet Access (HSPA) and / or Evolved HSPA (HSPA+). HSPA may include High Speed ​​Downlink (DL) Packet Access (HSDPA) and / or High Speed ​​UL Packet Access (HSUPA).

[0013] In an embodiment, 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).

[0014] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement a radio technology, such as New Radio (NR) radio access, capable of establishing the air interface 116 using NR.

[0015] In an embodiment, the base station 114a and the WTRUs 102a, 102b, 102c may implement multiple radio access technologies. For example, the base station 114a and the WTRUs 102a, 102b, 102c may jointly implement LTE and NR radio access, e.g., using a dual connectivity (DC) principle. Thus, the air interface utilized by the WTRUs 102a, 102b, 102c may be characterized by multiple types of radio access technologies and / or transmissions sent to / from multiple types of base stations (e.g., eNBs and gNBs).

[0016] In other embodiments, the base station 114a and the WTRUs 102a, 102b, 102c may implement a wireless 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 EDGE (GERAN), or the like.

[0017] 1A may be, for example, a wireless router, a Home Node B, a Home eNode B, or an access point and may utilize any suitable RAT for facilitating wireless connectivity within a localized 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, etc. 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 an 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. 1A, the base station 114b may have a direct connection to the Internet 110. Thus, the base station 114b may not be required to access the Internet 110 via the CN 106 / 115.

[0018] The RAN 104 / 113 can communicate with the CN 106 / 115, which can be any type of network configured to provide voice, data, application, and / or Voice over Internet Protocol (VoIP) services to one or more of the WTRUs 102a, 102b, 102c, 102d. The data may have various quality of service (QoS) requirements, such as different throughput requirements, latency requirements, error resilience requirements, reliability requirements, data throughput requirements, mobility requirements, etc. The CN 106 / 115 can provide call control, billing services, mobile location services, prepaid calling, Internet connectivity, video distribution, etc., and / or perform high-level security functions such as user authentication. Although not shown in FIG. 1A , it will be understood that the RAN 104 / 113 and / or the CN 106 / 115 can communicate directly or indirectly with other RANs employing 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 be utilizing NR radio technology, the CN 106 / 115 may also communicate with another RAN (not shown) employing GSM, UMTS, CDMA2000, WiMAX, E-UTRA, or WiFi radio technology.

[0019] The CNs 106 / 115 may also act as gateways for the WTRUs 102a, 102b, 102c, 102d to access the PSTN 108, the Internet 110, and / or other networks 112. The PSTN 108 may include a circuit-switched telephone network providing plain old telephone service (POTS). The Internet 110 may include a global system of interconnected computer networks and devices that use common communication protocols such as TCP, UDP, and / or IP in the TCP / IP Internet protocol suite. The networks 112 may include wired or wireless communication networks owned and / or operated by other service providers. For example, the network 112 may include another CN connected to one or more RANs that may employ the same RAT as the RANs 104 / 113 or a different RAT.

[0020] Some or all of the WTRUs 102a, 102b, 102c, 102d in the communications system 100 may include multi-mode capabilities (e.g., the WTRUs 102a, 102b, 102c, 102d may include multiple transceivers for communicating with different wireless networks over different wireless links). For example, the WTRU 102c shown in FIG. 1A may be configured to communicate with a base station 114a that may employ cellular-based wireless technology and a base station 114b that may employ IEEE 802.11 wireless technology.

[0021] 1B is a system diagram illustrating an example WTRU 102. As shown in FIG. 1B, the WTRU 102 may include, among other things, a processor 118, a transceiver 120, a transmit / receive element 122, a speaker / microphone 124, a keypad 126, a display / touchpad 128, non-removable memory 130, removable memory 132, a power source 134, a GPS chipset 136, and / or other peripherals 138. It will be understood that the WTRU 102 may include any sub-combination of the above elements while remaining consistent with an embodiment.

[0022] The processor 118 may be a general-purpose processor, a special-purpose processor, a conventional processor, a digital signal processor (DSP), multiple microprocessors, one or more microprocessors in association 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. While FIG. 1B depicts the processor 118 and the transceiver 120 as separate components, it will be understood that the processor 118 and the transceiver 120 may be incorporated together in an electronic package or chip.

[0023] The transmit / receive element 122 may be configured to transmit signals to or receive signals from a base station (e.g., base station 114a) over the air interface 116. For example, in one embodiment, the transmit / receive element 122 may be an antenna configured to transmit and / or receive RF signals. In an embodiment, the transmit / receive element 122 may be an emitter / detector configured to transmit and / or receive, for example, IR signals, UV signals, or visible light signals. In yet another embodiment, the transmit / receive element 122 may be configured to transmit and / or receive both RF signals and light signals. It will be understood that the transmit / receive element 122 may be configured to transmit and / or receive any combination of wireless signals.

[0024] 1B as a single element, the WTRU 102 may include any number of transmit / receive elements 122. More specifically, the WTRU 102 may employ MIMO 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.

[0025] 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 mentioned 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.

[0026] The processor 118 of the WTRU 102 may be coupled to and may receive user input data from a speaker / microphone 124, a keypad 126, and / or a display / touchpad 128 (e.g., a liquid crystal display (LCD) display unit or an organic light emitting diode (OLED) display unit). The processor 118 may also output user data to the speaker / microphone 124, the keypad 126, and / or the display / touchpad 128. The processor 118 may also access information from and store data in any type of suitable memory, such as non-removable memory 130 and / or removable memory 132. The non-removable memory 130 may include RAM, ROM, a hard disk, or any other type of memory storage device. The removable memory 132 may include a subscriber identity module (SIM) card, a memory stick, a secure digital (SD) memory card, etc. In other embodiments, the processor 118 may access information from memory that is not physically located on the WTRU 102, such as on a server or home computer (not shown), and may store data in that memory.

[0027] The processor 118 may receive power from the power source 134 and may be configured to distribute and / or control power to other components in the WTRU 102. The power source 134 may be any suitable device for powering the WTRU 102. For example, the power source 134 may include one or more dry batteries (e.g., nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel-metal hydride (NiMH), lithium-ion (Li-ion), etc.), solar cells, fuel cells, etc.

[0028] The processor 118 may also be coupled to a GPS chipset 136, which may be configured to provide location information (e.g., longitude and latitude) regarding the current location of the WTRU 102. In addition to or instead of information from the GPS chipset 136, the WTRU 102 may receive location information from base stations (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 obtain location information by way of any suitable location determination method while remaining consistent with an embodiment.

[0029] The processor 118 may further be coupled to other peripherals 138, which may include one or more software and / or hardware modules that provide additional features, functionality, and / or wired or wireless connectivity. For example, the peripherals 138 may include an accelerometer, an electronic compass, a satellite transceiver, a digital camera (for photos and / or videos), a USB port, a vibration device, a television transceiver, a hands-free headset, a Bluetooth module, a frequency modulation (FM) radio unit, a digital music player, a 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 peripherals 138 may include one or more sensors, which may be one or more of a gyroscope, an accelerometer, a Hall effect sensor, a magnetometer, a direction sensor, a proximity sensor, a temperature sensor, a time sensor, a geolocation sensor, an altimeter, a light sensor, a touch sensor, a barometer, a gesture sensor, a biometric sensor, and / or a humidity sensor.

[0030] The WTRU 102 may include a full-duplex radio, for which transmission and reception of some or all of the signals (e.g., associated with a particular subframe for both the UL (e.g., for transmission) and the downlink (e.g., for reception)) may be parallel and / or simultaneous. The full-duplex radio may include an interference management unit 139 for reducing and / or substantially eliminating self-interference through hardware (e.g., chokes) or signal processing by a processor (e.g., a separate processor (not shown) or the processor 118). In an embodiment, the WTRU 102 may include a half-duplex radio for transmission and reception of some or all of the signals (e.g., associated with a particular subframe for both the UL (e.g., for transmission) and the downlink (e.g., for reception)).

[0031] 1C is a system diagram illustrating the RAN 104 and the CN 106 according to an embodiment. As mentioned above, the RAN 104 may employ E-UTRA radio technology to communicate with the WTRUs 102a, 102b, 102c over the air interface 116. The RAN 104 may also communicate with the CN 106.

[0032] The RAN 104 may include eNode-Bs 160a, 160b, and 160c, although 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, and 160c may each include one or more transceivers for communicating with the WTRUs 102a, 102b, and 102c over the air interface 116. In one embodiment, the eNode-Bs 160a, 160b, and 160c may implement MIMO technology. Thus, the eNode-B 160a, for example, may use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a.

[0033] Each of the eNode-Bs 160a, 160b, 160c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, etc. As shown in FIG. 1C, the eNode-Bs 160a, 160b, 160c may communicate with one another via an X2 interface.

[0034] 1C may include a mobility management gateway (MME) 162, a serving gateway (SGW) 164, and a packet data network (PDN) gateway (i.e., PGW) 166. While each of the above elements is shown as part of the CN 106, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0035] The MME 162 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface and may act as a control node. For example, the MME 162 may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, bearer activation / deactivation, selecting a particular serving gateway during initial attach of the WTRUs 102a, 102b, 102c, etc. 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.

[0036] The SGW 164 may be connected to each of the eNode-Bs 160a, 160b, 160c in the RAN 104 via an S1 interface. The SGW 164 may generally route and forward user data packets to / from the WTRUs 102a, 102b, 102c. The SGW 164 may also perform other functions, such as anchoring the user plane during inter-eNode B handover, triggering paging when DL data is available for the WTRUs 102a, 102b, 102c, and managing and storing the context of the WTRUs 102a, 102b, 102c.

[0037] The SGW 164 may be connected to a PGW 166, which may provide the WTRUs 102a, 102b, 102c with access to packet-switched networks, such as the Internet 110, to facilitate communication between the WTRUs 102a, 102b, 102c and IP-enabled devices.

[0038] 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 landline communications devices. For example, the CN 106 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that acts as an interface between the CN 106 and the PSTN 108. The CN 106 may also provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired or wireless networks owned and / or operated by other service providers.

[0039] Although the WTRUs are described in Figures 1A-1D as wireless terminals, it is contemplated that in certain representative embodiments such terminals may use a wired communication interface (e.g., temporarily or permanently) with a communication network.

[0040] In an exemplary embodiment, the other network 112 may be a WLAN.

[0041] A WLAN in infrastructure basic service set (BSS) mode may have an access point (AP) for the BSS and one or more stations (STAs) associated with the AP. The AP may have access or interface to a distribution system (DS) or another type of wired / wireless network that carries traffic within and / or outside the BSS. Traffic originating from outside the BSS to a TA may arrive through the AP and be delivered to the STA. Traffic originating from a STA to a destination outside the BSS may be sent to the AP to be delivered to the respective destination. Traffic between STAs within the BSS may be sent through the AP; for example, a source STA may send traffic to the AP, and the AP may deliver traffic to the destination STA. Traffic between STAs within the BSS may be considered and / or referred to as peer-to-peer traffic. Peer-to-peer traffic may be sent (e.g., directly) between a source STA and a destination STA 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 the STAs (e.g., all of the STAs) within or using the IBSS may communicate directly with each other. IBSS mode communication is sometimes referred to herein as an "ad hoc" mode of communication.

[0042] When using an 802.11ac infrastructure mode of operation or a similar mode of operation, an AP can transmit beacons on a fixed channel, such as a primary channel. The primary channel may be a fixed width (e.g., 20 MHz bandwidth) or may be dynamically set by signaling. The primary channel may be the operating channel of the BSS and may be used by STAs to establish a connection with the AP. In certain exemplary embodiments, for example, in an 802.11 system, Carrier Sense Multiple Access with Collision Avoidance (CSMA / CA) may be implemented. In CSMA / CA, STAs (e.g., all STAs), including the AP, can sense the primary channel. If a particular STA senses / detects and / or determines that the primary channel is busy, the particular STA may yield. One STA (e.g., only one station) may transmit in a given BSS at any given time.

[0043] High-throughput (HT) STAs may use 40 MHz wide channels for communication, for example, by combining a primary 20 MHz channel with adjacent or non-adjacent 20 MHz channels to form a 40 MHz wide channel.

[0044] A very high throughput (VHT) STA can support 20 MHz, 40 MHz, 80 MHz, and / or 160 MHz wide channels. A 40 MHz and / or 80 MHz channel may be formed by combining contiguous 20 MHz channels. A 160 MHz channel may be formed by combining eight contiguous 20 MHz channels or two non-contiguous 80 MHz channels, the latter sometimes referred to as an 80+80 configuration. In the 80+80 configuration, after channel coding, the data may be passed through a segment parser that can split the data into two streams. Inverse fast Fourier transform (IFFT) processing and time-domain processing may be performed separately for each stream. The streams may be mapped to two 80 MHz channels, and the data may be transmitted by the transmitting STA. At the receiver of the receiving STA, the above operations for the 80+80 configuration may be reversed, and the combined data may be sent to the medium access control (MAC).

[0045] Sub-1 GHz operating modes are supported by 802.11af and 802.11ah. 802.11af and 802.11ah reduce the channel operating bandwidths and carriers compared to those 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, while 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 communication (MTC), such as MTC devices, in macro coverage areas. MTC devices may have specific capabilities, including, for example, specific bandwidths and / or limited bandwidth support (e.g., support only that bandwidth). MTC devices may include batteries with above-threshold battery life (e.g., very long battery life).

[0046] In WLAN systems capable of supporting multiple channels, as well as in 802.11n, 802.11ac, 802.11af, and 802.11ah, the channel bandwidth includes a channel that can be designated as a primary channel. The primary channel can have a bandwidth equal to the largest 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 that supports the smallest bandwidth operating mode among all STAs operating in the BSS. In an 802.11ah example, the primary channel may be 1 MHz wide for a STA (e.g., an MTC-type device) that supports 1 MHz mode (e.g., only supports 1 MHz mode), even if the AP and other STAs in the BSS support 2 MHz, 4 MHz, 8 MHz, 16 MHz, and / or other channel bandwidth operating modes. Carrier sensing and / or network allocation vector (NAV) setting can depend on the condition of the primary channel. If the primary channel is busy, for example due to a STA (that only supports 1 MHz operating mode) transmitting to the AP, the entire available frequency band may be considered busy even though most of the frequency band remains idle and available.

[0047] In the United States, the available frequency bands that may be used by 802.11ah are 902MHz to 928MHz. In South Korea, the available frequency bands are 917.5MHz to 923.5MHz. In Japan, the available frequency bands are 916.5MHz to 927.5MHz. The total bandwidth available for 802.11ah is 6MHz to 26MHz depending on the country code.

[0048] 1D 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, and 102c over the air interface 116. The RAN 113 may also communicate with the CN 115.

[0049] The RAN 113 may include gNBs 180a, 180b, and 180c, although 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 embodiment, the gNBs 180a, 180b, and 180c may implement MIMO technology. For example, the gNBs 180a, 180b may utilize beamforming to transmit signals to and / or receive signals from the gNBs 180a, 180b, and 180c. Thus, the gNB 180a may, for example, use multiple antennas to transmit wireless signals to and / or receive wireless signals from the WTRU 102a. In an embodiment, 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). Some of these component carriers may be on a licensed spectrum, and the remaining component carriers may be on an unlicensed spectrum. In an embodiment, the gNBs 180a, 180b, and 180c may implement coordinated multipoint (CoMP) technology. For example, the WTRU 102a may receive coordinated transmissions from the gNBs 180a and 180b (and / or 180c).

[0050] The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using transmissions associated with scalable numerology. For example, the OFDM symbol spacing and / or OFDM subcarrier spacing may vary for different transmissions, different cells, and / or different portions of the wireless transmission spectrum. The WTRUs 102a, 102b, 102c may communicate with the gNBs 180a, 180b, 180c using subframes or transmission time intervals (TTIs) of varying or scalable lengths (e.g., including different numbers of OFDM symbols and / or continuously varying lengths of absolute time).

[0051] 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 can communicate with the gNBs 180a, 180b, 180c without accessing another RAN (e.g., eNode-Bs 160a, 160b, 160c, etc.). In a standalone configuration, the WTRUs 102a, 102b, 102c can utilize one or more of the gNBs 180a, 180b, 180c as mobility anchor points. In a standalone configuration, the WTRUs 102a, 102b, 102c can 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 other RANs, such as eNode-Bs 160a, 160b, 160c. For example, the WTRUs 102a, 102b, 102c may implement a DC principle to communicate with one or more gNBs 180a, 180b, 180c and one or more eNode-Bs 160a, 160b, 160c substantially simultaneously. In a non-standalone configuration, the eNode-Bs 160a, 160b, 160c may act as mobility anchors for the WTRUs 102a, 102b, 102c, and the gNBs 180a, 180b, 180c may provide additional coverage and / or throughput for serving the WTRUs 102a, 102b, 102c.

[0052] Each of the gNBs 180a, 180b, 180c may be associated with a particular cell (not shown) and may be configured to handle radio resource management decisions, handover decisions, scheduling of users in the UL and / or DL, support for network slicing, dual connectivity, interworking between NR and E-UTRA, routing of user plane data to user plane functions (UPFs) 184a, 184b, routing of control plane information to access and mobility management functions (AMFs) 182a, 182b, etc. As shown in FIG. 1D , the gNBs 180a, 180b, 180c may communicate with each other via an Xn interface.

[0053] 1D may include at least one AMF 182a, 182b, at least one UPF 184a, 184b, at least one Session Management Function (SMF) 183a, 183b, and possibly a Data Network (DN) 185a, 185b. While each of the above elements is shown as part of the CN 115, it will be understood that any of these elements may be owned and / or operated by an entity other than the CN operator.

[0054] The AMF 182a, 182b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N2 interface and may act as a control node. For example, the AMF 182a, 182b may be responsible for authenticating users of the WTRUs 102a, 102b, 102c, supporting network slicing (e.g., handling different PDU sessions with different requirements), selecting a particular SMF 183a, 183b, managing registration areas, terminating NAS signaling, mobility management, etc. Network slicing may be used by the AMF 182a, 182b to customize CN support for the WTRUs 102a, 102b, 102c based on the type of service being utilized for the WTRUs 102a, 102b, 102c. For example, 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 High-Capacity Mobile Broadband (eMBB) access, and / or services relying on Machine-Type Communications (MTC) access, etc. The AMFs 182a, 182b may provide a control plane function for switching between the RAN 113 and other RANs (not shown) that employ other radio technologies, such as LTE, LTE-A, LTE-A Pro, and / or non-3GPP access technologies, such as WiFi.

[0055] The SMFs 183a, 183b may be connected to the AMFs 182a, 182b in the CN 115 via an N11 interface. The SMFs 183a, 183b may also be connected to the UPFs 184a, 184b in the CN 115 via an N4 interface. The SMFs 183a, 183b may select and control the UPFs 184a, 184b and configure the routing of traffic through the UPFs 184a, 184b. The SMFs 183a, 183b may perform other functions, such as managing and assigning UE IP addresses, managing PDU sessions, controlling policy enforcement and QoS, and providing downlink data notification. The PDU session type may be IP-based, non-IP-based, Ethernet-based, etc.

[0056] The UPFs 184a, 184b may be connected to one or more of the gNBs 180a, 180b, 180c in the RAN 113 via an N3 interface, 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. The UPFs 184a, 184b may also 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, and providing mobility anchoring.

[0057] The CN 115 may facilitate communication with other networks. For example, the CN 115 may include or communicate with an IP gateway (e.g., an IP Multimedia Subsystem (IMS) server) that interfaces between the CN 115 and the PSTN 108. The CN 115 may also provide the WTRUs 102a, 102b, 102c with access to other networks 112, which may include other wired or wireless networks owned and / or operated by other service providers. In one embodiment, the WTRUs 102a, 102b, 102c may be connected to local data networks (DNs) 185a, 185b through the UPFs 184a, 184b via an N3 interface to the UPFs 184a, 184b and an N6 interface between the UPFs 184a, 184b and the DNs 185a, 185b.

[0058] 1A-1D and the corresponding description thereof, one or more or all of the functions described herein with respect to one or more of the WTRUs 102a-d, base stations 114a-b, eNode-Bs 160a-c, MME 162, SGW 164, PGW 166, gNBs 180a-c, AMFs 182a-b, UPFs 184a-b, SMFs 183a-b, DNs 185a-b, and / or any other devices described herein may be performed by one or more emulation devices (not shown). The emulation devices may be one or more devices configured to emulate one or more or all of the functions described herein. For example, the emulation devices may be used to test other devices and / or to simulate network and / or WTRU functionality.

[0059] The emulation device may be designed to implement one or more tests of other devices in a lab environment and / or an operator network environment. For example, one or more emulation devices may perform one or more or all functions while fully or partially implemented and / or deployed as part of a wired and / or wireless communication network to test other devices in the communication network. One or more emulation devices may perform one or more or all functions while temporarily implemented / deployed as part of a wired and / or wireless communication network. The emulation device may be directly coupled to another device for testing and / or may perform testing using wireless communication.

[0060] One or more emulation devices may perform one or more functions without being implemented / deployed as part of a wired and / or wireless communication network. For example, the emulation devices may be utilized in test labs and / or test scenarios in non-deployed (e.g., test) wired and / or wireless communication networks to implement testing of one or more components. One or more emulation devices may be test equipment. Direct RF coupling and / or wireless communication via RF circuitry (which may include, e.g., one or more antennas) may be used by the emulation devices to transmit and / or receive data.

[0061] Based on the general requirements set by the ITU Radiocommunication Sector (ITU-R), the Next Generation Mobile Networks (NGMN) group, and the 3rd Generation Partnership Project (3GPP), a broad classification of use cases for emerging 5G systems can be denoted as enhanced mobile broadband (eMBB), massive machine-type communications (mMTC), and ultra-reliable low-latency communications (URLLC). Different use cases may focus on different requirements, such as higher data rates, higher spectral efficiency, low power and higher energy efficiency, lower latency, and higher reliability. A wide range of spectrum bands, ranging from 700 MHz to 80 GHz, is being considered for various deployment scenarios.

[0062] It is well known that as carrier frequencies increase, severe path loss becomes a significant constraint for ensuring sufficient coverage area. Transmissions in millimeter wave systems may further suffer from non-line-of-sight losses, such as diffraction loss, penetration loss, oxygen absorption loss, and foliage loss. During initial access, the base station and WTRU may need to overcome these significant path losses to discover each other. Utilizing tens or even hundreds of antenna elements for the generated beamforming signals is an effective way to compensate for severe path loss by providing significant beamforming gain. Beamforming techniques may include digital, analog, and hybrid beamforming.

[0063] Cell search is the procedure by which a WTRU acquires time and frequency synchronization with a cell and finds the cell ID of that cell. LTE synchronization signals are transmitted in the 0th and 5th subframes of every radio frame and are used for time and frequency synchronization during initialization. As part of the system acquisition process, the WTRU sequentially synchronizes to OFDM symbols, slots, subframes, half-frames, and radio frames based on the synchronization signals. The two synchronization signals are the primary synchronization signal (PSS) and the secondary synchronization signal (SSS). The PSS is used to derive slot, subframe, and half-frame boundaries. It also provides the physical layer cell identity (PCI) within a cell identity group. The SSS is used to derive radio frame boundaries. It also allows the WTRU to determine the cell identity group, which can range from 0 to 167.

[0064] Following successful synchronization and PCI acquisition, the WTRU decodes the Physical Broadcast Channel (PBCH) with the help of the CRS to obtain MIB information regarding system bandwidth, system frame number (SFN), and PHICH configuration. Note that the LTE synchronization signal and PBCH are transmitted continuously according to a standardized periodicity.

[0065] It is agreed that NR does not require the WTRU to perform blind detection of the NR-PBCH transmission scheme or the number of antenna ports. For NR-PBCH transmission, a single, fixed number of antenna ports is supported. For NR-PBCH transmission, NR can employ both digital and analog beamforming techniques, especially in higher frequency bands. Digital beamforming using multi-antenna technology and / or analog beamforming using single- or multi-port beamforming techniques may be considered in NR. For the reference signal for NR-PBCH demodulation, NR can employ a synchronization signal (e.g., NR-SSS) or the use of built-in DMRS for NR-PBCH demodulation. If a mobility reference signal (MRS) is supported in the SS block, the MRS may be multiplexed into the SS block. The numerology of the NR-PBCH may be the same as or different from that of NR-SSS. Embodiments of digital beamforming using multi-antenna technology, analog beamforming using single- or multi-port beamforming technology, or a hybrid scheme combining both digital and analog beamforming are considered for data transmission in connected mode. Similar techniques should be considered for idle mode or initial access and designed for broadcast channels such as NR-PBCH for optimal system performance.

[0066] The NR-PSS and / or NR-SSS may be used as reference signals for NR-PBCH demodulation. Alternatively, a reference signal dedicated to the NR-PBCH may be used. Such a reference signal may be embedded within the NR-PBCH signal and channel. Even without an additional signal or reference signal, a receiver may still be able to demodulate the NR-PBCH signal and channel. A reference signal or demodulation reference signal (DMRS) for such demodulation is specific to the NR-PBCH and may be multiplexed and embedded within the NR-PBCH resources. In doing so, the NR-PBCH-dedicated demodulation reference signal (DMRS) may be used for NR-PBCH demodulation. The term DMRS, as used herein, can refer to one or more demodulation reference signals.

[0067] Time division multiplexing of NR-SS and NR-PBCH may be preferable in order to use NR-SS (either NR-PSS or NR-SSS) as a reference signal for NR-PBCH demodulation.

[0068] Figure 2 shows the NR-PBCH multiplexed with the NR-PSS and NR-SSS, where the NR-PBCH, NR-PSS, and NR-SSS are multiplexed in a TDM manner. The NR-PBCH signal and channel may be repeated and placed before or after the NR-SS. Such a design may be used for, but is not limited to, carrier frequency offset compensation purposes. As shown in Figure 2, the PSSs 204, 214, and 226, the SSSs 206, 218, and 228, and the PBCHs 208, 210, 216, 220, 224, and 230 each occupy the same frequency. In the first example, Option 1 202, the PSS 204 is transmitted before the SSS 206, followed by the first PBCH 208 and the second PBCH 210. In Option 2 212, the PSS 214 is transmitted before the PBCH 216, followed by the SSS 218 and the PBCH 220. Option 2 212 may be used to provide PBCH information before completing synchronization. In option 2 212, PSS 214 is transmitted before PBCH 216, SSS 218, and PBCH 220. In yet another option, option 3 222, PBCH 224 is transmitted before PSS 226, which is followed by SSS 228 and PBCH 230. Option 3 222 may allow PBCH information to be received prior to any synchronization information.

[0069] Similarly, FIG. 3 is a timing diagram 300 illustrating the use of NR-SS signals in two different options 310, 320. Either the NR-PSS or the NR-SSS or both may be repeated and placed before or after the NR-PBCH. The repeated NR-PSS or NR-SSS may also be used for, but not limited to, carrier frequency offset estimation or compensation purposes. As shown in FIG. 3, in option 4 310, a first PSS transmission 312 may occur before a second PSS transmission 314. After the second PSS transmission 314, an SSS transmission 316 may be transmitted, which is followed by a PBCH transmission 318. In option 5 320, an SSS transmission 322 may be transmitted before a PSS transmission 324. An SSS transmission 326 may follow the PSS transmission 324 along with a PBCH transmission 328.

[0070] 4 is an example diagram of a first NR-PBCH-dedicated demodulation reference signal design 400 in which one antenna port is used in two options 401, 420. In both option 1 402 and option 2 420, one antenna is used for the NR-PBCH-dedicated DMRS. In the first option, option 1 402, repeated NR-PBCH-dedicated DMRSs are placed at the same frequency location or subcarrier to aid in carrier frequency offset (CFO) estimation. In one example, DMRS 404 is at the same frequency location as DMRS 406, DMRS 408 is at the same frequency location as DMRS 410, DMRS 412 is at the same frequency location as DMRS 414, and DMRS 416 is at the same frequency location as DMRS 418. In the second option, option 2 420, a different pattern is used for the NR-PBCH DMRSs, in which the DMRSs are placed with a fixed offset in the frequency domain to cover other frequency locations or subcarriers and / or obtain frequency diversity. For example, if the DMRS density is 1 / 6 for both NR-PBCH symbols, the DMRS in the second PBCH OFDM symbol may be offset by three REs relative to the first PBCH OFDM symbol. This can create a perfect interdigitated pattern of DMRS between the two NR-PBCH OFDM symbols. The combined or joint DMRS in the two PBCH OFDM symbols can achieve a DMRS density of 1 / 3 in lower Doppler channels, which may improve channel estimation performance. This may come at the expense of not being able to estimate or compensate for CFO using the DMRS. However, in this case, the mapping of data REs may result in some data REs being repeated when PBCH data is repeated in the second PBCH OFDM symbol, which may be used for CFO estimation and compensation. As shown in option 2 420, DMRS 422 is offset from DMRS 430, DMRS 424 is offset from DMRS 432, DMRS 426 is offset from DMRS 434, and DMRS 428 is offset from DMRS 436.

[0071] Figure 5 is a third example of an NR-PBCH dedicated demodulation reference signal design 500 using two antenna ports in two options 502, 540. NR-PBCH dedicated DMRS with two antenna ports is shown in Figure 5. In the first option 502, repeated NR-PBCH dedicated DMRS 504-534 are placed at the same frequency location or subcarrier for each antenna port to aid in carrier frequency offset (CFO) estimation. In the second option, option 2 540, a different pattern for the NR-PBCH DMRS is used, in which the DMRS at the two antenna ports are placed with a fixed offset in the frequency domain to cover other frequency locations or subcarriers and / or obtain frequency diversity. In option 2 540, DMRS1 542, 548, 550, 556, 558, 564, 566, 572 and DMRS2 544, 546, 552, 554, 560, 562, 568, 570 are alternated in frequency.

[0072] In one or more embodiments, hybrid dedicated demodulation reference signals (H-DMRS) may be utilized. Some of the repeated NR-PBCH-dedicated DMRS may be located at the same frequency location or subcarrier for each antenna port to aid in CFO estimation, and other repeated NR-PBCH-dedicated DMRS may be located at different frequency locations or subcarriers and / or obtain frequency diversity.

[0073] 6 is a diagram 600 of two different NR-PBCH hybrid dedicated demodulation reference signal (H-DMRS) designs 602, 620. As shown in FIG. 6, in the hybrid one-port approach 602, DMRS 604 may be in the same frequency location as DMRS 606, and DMRS 608 may be in a different frequency location than DMRS 610. DMRS 612 may be located in the same frequency location as DMRS 614, and DMRS 616 may be located in a different frequency location than DMRS 618. In the hybrid two-port 620 approach, DMRS1 622 may be in the same frequency location as DMRS1 624, DMRS2 626 may be in the same frequency location as DMRS2 628, DMRS1 630 may be in the same frequency location as DMRS2 632, DMRS2 634 may be in the same frequency location as DMRS1 636, DMRS1 638 may be in the same frequency location as DMRS1 640, DMRS2 642 may be in the same frequency location as DMRS2 644, DMRS1 646 may be in the same frequency location as DMRS2 648, and DMRS2 650 may be in the same frequency location as DMRS1 652. The DMRSs are transmitted on two different ports. In an example, DMRS1 is transmitted from antenna port 1 and DMRS2 is transmitted from antenna port 2 with a fixed offset in frequency. If the offset is zero, the DMRSs on both antenna ports have the same frequency location.

[0074] In an embodiment, a non-uniform DMRS density may be used, which may employ different densities of demodulation reference signals (DMRS). A higher density of DMRS may be placed in the OFDM symbol of the NR-PBCH to support channel estimation. However, to reduce DMRS overhead, a lower density of DMRS may be placed in the second OFDM symbol of the NR-PBCH. These DMRS may be the same as the DMRS in the first OFDM symbol of the NR-PBCH on the same subcarriers, which may facilitate CFO estimation. This may reduce the code rate. If the second symbol is closer to the SSS, channel estimation may be supported by the use of the SSS.

[0075] 7 illustrates a non-uniform density NR-PBCH demodulation reference signal 700 for use with two different configuration options 702, 720. In an embodiment, precoding may or may not be applied to pilot subcarriers. Precoding may also be used to remove second OFDM symbol common phase error to improve NR-PBCH detection performance at the receiver.

[0076] NR-PBCH / SS multiplexing and DMRS allocation embodiments may enable efficient and high-performance NR-PBCH demodulation. Figures 4 and 5 show how DMRSs are mapped to the same frequency location across symbols, e.g., to improve performance of CFO estimation. These figures also show that DMRSs may be mapped with a fixed frequency offset across symbols, thereby improving channel estimation due to the resulting frequency diversity.

[0077] Both of these performance-enhancing techniques may be achieved using hybrid DMRS mapping similar to that shown in FIG. 6. In FIG. 7 and other embodiments, PSS and / or SSS may be used to assist channel estimation with lower DMRS density. This is sometimes referred to as a diverse density (DD) method. FIG. 7 illustrates embodiments of DD-DMRS1-port 702 and DD-DMRS2-port 720. In the DD-DMRS1-port 702 embodiment, a PSS signal 704 may be transmitted before an SSS signal 706. DMRS signals 708, 712, 714, and 718 may be transmitted at a first time prior to the PSS signal 704. DMRS signals 710 and 716 may be transmitted at a second time after the SSS signal 706. Fewer DMRS signals may be transmitted at the second time. The DMRS signals 708, 710, 714, and 716 at the first and second times may overlap in frequency as shown. In the example of DD-DMRS2 port 720, more DMRS signals 726-744 may be transmitted than in the example of DD-DMRS1 port 702. These DMRSs 726-744 may be transmitted before the PSS 722 and after the SSS 724, similar to the 1-port option 702.

[0078] In one example, NR-PSS and NR-SSS have different bandwidth allocations compared to the NR-PBCH. For example, NR-PSS and NR-SSS may use 12 RBs, while the PBCH may use 24 RBs. Thus, there are 12 RBs of the PBCH that overlap with the NR-PSS / NR-SSS and another 12 that do not overlap with the NR-PSS / NR-SSS. At the receiver after cell ID detection, the NR-PSS and NR-SSS may be considered as known sequences that can serve as reference symbols for demodulating the overlapping RBs of the NR-PBCH. This technique can be used to improve performance and / or efficiency of the design. Performance improvement can be achieved by allowing the NR-PSS and / or NR-SSS to assist in channel estimation, and efficiency can be achieved by allowing the reduction or even complete elimination of DMRS within the SS bandwidth. This concept is illustrated in FIG. 8. The left side 800 of FIG. 8 shows a design in which the SS block mapping order is NR-[PSS PBCH1 SSS PBCH2]. 8 shows a design where the SS block mapping order is NR-[PBCH1 PSS SSS PBCH2]. The same design for DMRS may be applied to other possible mapping orders, such as NR-[PSS-SSS-PBCH1-PBCH2] and NR-[PSS-PBCH1-PBCH2-SSS].

[0079] As shown in FIG. 8, the central RBs 806, 808 of NR-PBCH symbol 1 802 or symbol 2 804 have no DMRS or have reduced-density (hereinafter, reduced-density) DMRS. This increases the number of REs available for data transmission and therefore reduces the effective code rate for the same payload. If channel estimation performance is similar, the reduced effective code rate may improve performance. If DMRS is not used for the central RBs, the PSS 810 or SSS 812, or both, may be used for channel estimation. If reduced-density DMRS is used for the central RBs, the PSS 810 or SSS 812, or both, may be used as additional support along with the existing DMRS to perform 2D channel estimation for the central RBs. PBCH1 DMRSs 814 and 818 may include DMRS at full density. The same may be true for PBCH2 DMRSs 816 and 820. Note that the reduction in NR-PBCH density may also depend on the distance from the NR-SSS. For NR-[PSS PBCH1 SSS PBCH2] 800, both NR-PBCHs may have the same density for DMRS or no DMRS. However, in the NR-[PBCH1 PSS SSS PBCH2] configuration 830, PBCH1 may have higher DMRS density than PBCH2, even in RBs that overlap with NR-PSS and NR-SSS.

[0080] As shown in NR-[PBCH1 PSS SSS PBCH2] configuration 830, PSS 832 and SSS 834 are between PBCH1 836 and PBCH2 838. PBCH1 836 and PBCH2 838 consist of no DMRS or reduced-density DMRS in the center frequency portions 836 and 838. PBCH1 DMRS 840 and 844 can include DMRS at full density. The same may be true for PBCH2 DMRS 842 and 846.

[0081] The DMRS density can be 1 / 3, 1 / 4, 1 / 6, or another density depending on the selected design. When the DMRS density is 1 / 3, it means that one in three resource elements (REs) is used for the DMRS. Similarly, when the DMRS density is 1 / 4 or 1 / 6, it means that one in four or six resource elements (REs) is used for the DMRS, respectively.

[0082] The various disclosed options can offer different performance benefits and efficiency improvements that may be applicable in different scenarios. To enable all possible options, simple signaling may be provided to indicate which option is being used, for example, in NR-SSS and / or new radio tertiary synchronization signal (NR-TSS).

[0083] FIG. 9 is a flow diagram 900 detailing exemplary performance of configurable NR-PBCH demodulation. The following exemplary procedure may be used in a receiver: An NR-PSS signal may be searched for (902). Timing and frequency information may be obtained using the NR-PSS / NR-SSS (904). A configuration indicator carried on the NR-SSS indicating the reference signal configuration may be decoded, and the configuration indicator may be checked (906). For example, FIG. 9 shows two overall reference configurations, Configuration 1 908 and Configuration 2 910. In Configuration 1 908, the PBCH reference signal is embedded using DMRS. The DMRS may be mapped according to one of the various configurations shown in FIGS. 4-7. This information may also be carried on the NR-SSS. In Configuration 2 910, a joint SS / DMRS reference signal is provided. An exemplary scenario for Configuration 2 910 is when the PBCH bandwidth is larger than the SS bandwidth, so reduced DMRS density may be used in the overlapping bandwidth. This may be consistent with embodiments disclosed, particularly with reference to one or more of Figures 7 or 8. Regardless of the selection of configuration 1 908 or configuration 2 910, the NR-PBCH may ultimately be demodulated 916 using the estimated channel response.

[0084] This non-uniform DMRS mapping for configuration 2 910 is shown in Figures 7 and 8. The exact density of DMRS in the overlap region can range from 1, which corresponds to using the same density in the non-overlapping region, to 0, which corresponds to no DMRS in the overlap region. Also, the DMRS mapping portion may use any of the same techniques shown in Figures 4-6. Finally, as with configuration 1 908, this lower configuration level may be signaled from the NR-SSS and / or NR-TSS. Channel estimation using only DMRS (configuration 1 908) may be performed (912). Alternatively, channel estimation using joint SS / DMRS (configuration 2 910) may be selected accordingly (914). The receiver may use a 2D (time-frequency) based algorithm for better joint interpolation across time and frequency. OFDM symbols for the NR-PBCH may be received. The channel estimates can be used to equalize and detect the NR-PBCH symbols, and the symbols can be decoded using an appropriate channel decoder, for example, using polar decoding (916).

[0085] The NR-PBCH may be transmitted over N OFDM symbols. In a first embodiment, the NR-PBCH coded bits are mapped across REs in N PBCH symbols, where N is the number of PBCH symbols in the NR-SS block. In a second embodiment, the NR-PBCH coded bits are mapped across REs in a PBCH symbol, and that NR-PBCH symbol is copied to N-1 NR-PBCH symbols in the NR-SS block.

[0086] For example, for N=2, the following may be used: In a first embodiment, the NR-PBCH coded bits are mapped across the REs in both PBCH symbols; In a second embodiment, the NR-PBCH coded bits are mapped across the REs in an NR-PBCH symbol, and that NR-PBCH symbol is copied to the second NR-PBCH symbol NR-SS block.

[0087] In a first embodiment in which the NR-PBCH coded bits are mapped across REs in both PBCH symbols, the NR-PBCH coded bits are mapped across REs in the N PBCH symbols without repetition. NR-PBCH resources may be allocated in different ways. A frequency-first mapping solution may be used. Data-to-RE mapping may be mapped in frequency first as an order. RE mapping may be performed first in frequency and then in time. RE mapping in frequency may be followed by RE mapping in time. RE mapping may be applied to data, DMRS, or sequences, etc. In this case, the QPSK symbol generated from the data coming from the channel encoder is mapped to the first NR-PBCH OFDM symbol first, and the first NR-PBCH OFDM symbol is followed by the second or remaining N-1 NR-PBCH OFDM symbols. Time-first mapping may also be used. The QPSK symbols generated from the data coming from the channel encoder may be first mapped to the first RE of each NR-PBCH OFDM symbol, which is followed by the second RE of each NR-PBCH OFDM symbol, etc. A hybrid method may also be used, in which the QPSK symbols generated from the data coming from the channel encoder are first mapped to the first (n) RBs of each NR-PBCH OFDM symbol, which is followed by the second (n) RBs of each NR-PBCH OFDM symbol, where "n" may be a predefined or configured integer known to both the transmitter and the receiver.

[0088] In a second embodiment in which NR-PBCH coded bits are mapped across REs in an NR-PBCH symbol, that NR-PBCH symbol is copied to the NR-SS block of a second NR-PBCH symbol, with repetition, so that the NR-PBCH coded bits are mapped across REs in the PBCH symbol. In a simple design, the NR-PBCH data (and / or DMRS) may be copied to the second or remaining N-1 NR-PBCH OFDM symbols. In another embodiment, frequency hopping of the data may be performed. Data mapped to one RB in the first NR-PBCH symbol may be mapped to another RB in the second NR-PBCH symbol. This frequency hopping pattern is known to the receiver, so it may be able to combine them to increase the frequency of decoding. The DMRS in this case does not need to frequency hop. Therefore, the CFO may be estimated at the receiver using the DMRS position. In another embodiment, frequency hopping may be used only for the 12 RBs that do not overlap with the NR-PSS and NR-SSS. In one embodiment, an offset may be applied to the second PBCH symbol relative to the first PBCH symbol. This offset may be related to the phase of the data symbols. This phase offset may be detected at the receiver, allowing implicit information to be decoded. For example, if the phase difference between the first and second symbols is [0, pi / 2, pi, 3pi / 2], two bits of implicit information may be indicated. It is also possible to have a shift known based on the cell ID. In this case, the purpose is not to indicate anything, but to randomize the data using a cell-specific shift. This offset may be related to the frequency position of the data symbols. Like the phase, this may be a cell-specific shift that is known to increase randomization or that can be used to blindly decode several bits. The shift may be a frequency shift, a time shift, a phase shift, etc., or one or more combinations thereof.

[0089] In an embodiment, a hybrid design may be implemented. In this hybrid design, the first 12 central RBs of both PBCH symbols may be filled with all data. This data may then be copied to the 12 side RBs, e.g., 6+6 on either side of the center. This design is important because all data symbols are present in the center RB. If the SNR is good, this allows the WTRU to detect the PBCH using a smaller bandwidth, e.g., the center 12 RBs. In this way, the WTRU only needs to receive and demodulate the center 12 RBs, which may also save power. Frequency hopping may or may not be used here.

[0090] If frequency hopping is used, the center portion of the first symbol may be copied into the 12 RBs of the second symbol, and the center portion of the second symbol may be copied into the 12 RBs of the first symbol. Since the receiver knows this pattern, it can carefully extract and assemble the DMRS blocks before transmitting to the channel decoder. This may result in good performance in the WTRU at lower SNRs, but careful demapping of the REs is required during combining at the receiver.

[0091] In another embodiment, the RE mapping may be a function of the cell ID and / or the SS block ID. This embodiment is motivated by interference randomization. Before detecting the NR-PBCH, the WTRU should have detected the cell ID using the NR-PSS / NR-SSS. Also, in some cases, the SS block ID may already be known before encoding the NR-PBCH. This may be the case, for example, if a TSS was transmitted and the SS block ID was carried by the TSS, or if some prior knowledge of the SS block index is available.

[0092] It may be desirable to use DMRS RE-mapping as a function of cell ID or SS block index, or both. If the frequency location of the DMRS depends on cell ID, it may reduce interference from neighboring cells. For example, this may include shifting the location of one, more, or all DMRSs in the OFDM symbols for the NR-PBCH. In one or more embodiments, the terms SS block ID, SS block index, and SS block time index may be used interchangeably.

[0093] At the receiver, once the WTRU detects the NR-PSS / NR-SSS, the cell ID and / or SS block ID will be known. The WTRU may be able to identify the location of the DMRS for the NR-PBCH using the cell ID and / or SS block ID and the mapping function. The WTRU can then continue channel estimation for the PBCH using the DMRS. PBCH demodulation and decoding then occurs. If different cells transmit DMRS in different locations, interference may be reduced, mitigated, or avoided.

[0094] To achieve better randomization, the sequence of the DMRS (e.g., sequence or scrambling sequence) may depend on the cell ID or the SS block index, or both. The sequence of the DMRS (e.g., sequence or scrambling sequence) may depend on other information, such as the half radio frame indicator, jointly with, separately from, or separately from the SS block index or cell ID. The DMRS may use any different sequence. Optionally, this may include an M sequence, a Gold sequence, a ZC sequence, or a PN sequence. The different parameters of these sequences may be a function of the cell ID or the SS block index.

[0095] In either case, the DMRS of the PBCH may be used as the DMRS of the PDSCH. This also applies to the RBs occupied by the PBCH. Rate matching may be used to convert 512 the coded bits to all used data REs, which may vary depending on the DMRS design.

[0096] Different sequences can be used as DMRS for the NR-PBCH. One sequence of interest is a maximum length sequence (M-sequence). Due to their noise-optimal properties and very good correlation properties, M-sequences can serve a dual purpose. M-sequences may be used to convey information and may serve as reference symbols for demodulation of the NR-PBCH.

[0097] For example, if 24 RBs are allocated to the NR-PBCH, two DMRSs may be present in each RB in each OFDM symbol. Therefore, 48 symbols may be required as DMRSs in each OFDM symbol. Depending on the particular embodiment or implementation choice, there may be a design choice to have fewer or more DMRSs. The M sequence is 2 M It has a length of -1 and allows for a variety of options.

[0098] FIG. 10A shows a circuit configuration 1000 configured to generate an M-sequence of length 7. As shown in FIG. 10A, there are seven stages 1002-1014, representing the seven bits available for shifting. At each clock pulse of the circuit configuration, bits from stage 6 1012 are shifted into stage 7 1014, bits from stage 5 1010 are shifted into stage 6 1012, bits from stage 4 1008 are shifted into stage 5 1010, bits from stage 3 1006 are shifted into stage 4 1008, bits from stage 2 1004 are shifted into stage 3 1006, and bits from stage 1 1002 are shifted into stage 2 1004. The output of stage 7 1014 is ORed (1016) with the output of stage 6 1012 and provided to stage 1 1002. In this manner, input bits are continually shifted into stage 1. Output 1018 is shown from stage 7 1014. In this way, a length-127 M-sequence can be generated from a length-7 shift register using seven stages, which can be used for one or both of the OFDM symbols of the NR-PBCH.

[0099] FIG. 10B shows a length-63 M-sequence that may be generated from a length-6 shift register 1020. Thus, there are only six stages 1022-1032 shown in FIG. 10B. Output 1036 may result from stage 6 1032. OR 1034 of stage 5 1030 and stage 6 1032 may be provided to stage 1 1022. This sequence may be used for one or both of the NR-PBCH OFDM symbols with some repetition or padding along with some known symbols. For example, it may be padded with all ones to match the length of the sequence to the number of required DMRSs. It may also be possible to generate a length-31 M-sequence using a length-5 shift register and repeat it to cover all DMRSs in each OFDM symbol. The same or different sequences may be used for the other OFDM symbols. It may also be possible to concatenate two different M-sequences of the same or different lengths. This may allow for two shifts at the expense of higher correlation. This increases the amount of information transmitted at the expense of detection reliability. However, if the sequence is long, this may be a viable option. The M sequence may be scrambled with another sequence, or another PN sequence may be used. Parameters such as the shift or polynomial of the sequence may be a function of the cell ID. This may enable orthogonal DMRS between different cells.

[0100] Longer length M-sequences can provide better correlation properties. These sequences can be used with different shifts. Using different shifts, it may be possible to implicitly indicate [5, 6, 7] bits of information using 31, 62, or 127 M-sequence bit lengths. One option may include, but is not limited to, indicating the SS block index, details to aid in channel decoding of the NR-PBCH, including information about polar code and beam ID. This may also be used for any other information requiring very low latency. If the SS block ID is not indicated using DMRS but is known prior to decoding of the NR-PBCH, the shift or polynomial-like parameters of the sequence may be a function of the SS block ID. The shift may be, but is not limited to, a frequency shift, a time shift, a phase shift, or a position shift. A combination of these shift types may also be used.

[0101] FIG. 11 is a flowchart 1100 illustrating a procedure used for exemplary receiver processing and information detection. The receiver may first acquire timing and frequency using NR-PSS and NR-SSS (1102). The receiver may receive OFDM symbols for the NR-PBCH (1104). DMRS RE allocation may be a function of cell ID and / or SS block ID (1106), and DMRS RE mapping may be discovered based on the cell ID and / or SS block ID. The SS block ID may be implicit in the DMRS (1108), and the receiver may use NR-PSS to estimate the channel and pre-equalize the REs containing the NR-PBCH DMRS (1110). The receiver may extract frequency-domain symbols for the NR-PBCH DMRS (1118). These symbols are correlated with the original M-sequence used to generate the PBCH DMRS. A strong peak is given at one of the offsets. This, like the SS block index, provides the information embedded in the DMRS. If multiple M-sequences are used, careful extraction and correlation may be used to identify the transmit shift for each M-sequence. The detected shift may be used to generate a local copy of the DMRS, which may be used to detect and decode the NR-PBCH. The DMRS sequence may be a function of the cell ID and / or SS block ID (1112), and the local copy of the DMRS may be generated based on the cell ID and / or SS block ID. The local copy of the DMRS may be used for channel estimation for the NR-PBCH and demodulation / decoding of the NR-PBCH. The local copy may be found (1114) via a lookup in a local table or database (1116).

[0102] In another embodiment, ZC sequences may be used as DMRSs for the NR-PBCH. They may be used to deliver information using different cyclic shifts and may serve as reference symbols for demodulation of the NR-PBCH. For example, if 24 RBs are allocated to the NR-PBCH, there may be two DMRSs in each RB in each OFDM symbol. Therefore, N symbols may be required for DMRSs in each OFDM symbol. In one embodiment, N may be 48. The length of the ZC sequence may be selected to match the number of DMRSs. The best route for the ZC sequence may be determined by simulation.

[0103] It may also be possible to concatenate two different ZC sequences of the same or different lengths. The ZC sequence may be scrambled with another PN sequence or M sequence. Parameters, such as the root of the ZC sequence or the cyclic shift of the ZC sequence, may be a function of the cell ID. This may enable orthogonal DMRS between different cells. Longer ZC sequence lengths result in better correlation properties. These sequences may be used with different cyclic shifts. Using different shifts, it may be possible to carry [4, 5, 6] bits of information for ZC sequences of lengths 31, 62, and 127, respectively, which may be used to indicate information to assist in channel decoding of the NR-PBCH. This may include information about polar encoding and / or decoding, including beam ID. It is also possible to use different roots of the ZC sequence. The WTRU may be able to blindly identify the ZC sequence used. This may be used to carry implicit information as well. This may be used for any other information requiring very low latency. If the SS block ID is not indicated using DMRS but is known prior to decoding of the NR-PBCH, parameters such as the root of the ZC sequence or the cyclic shift of the ZC sequence may be a function of the SS block ID.

[0104] For receiver processing, the following procedures may be used to detect information: The receiver may first acquire timing and frequency using NR-PSS / NR-SSS. The receiver may receive OFDM symbols of the NR-PBCH. The DMRS RE allocation may be a function of the cell ID and / or SS block ID, and the DMRS RE mapping may be obtained based on the cell ID and / or SS block ID. The DMRS sequence may be a function of the cell ID and / or SS block ID, and a local copy of the DMRS may be generated based on the cell ID and / or SS block ID. The local copy of the DMRS may be used for channel estimation for the NR-PBCH and demodulation / decoding of the NR-PBCH.

[0105] Gold sequences may be used for DMRS. Gold sequences may be generated by multiplying two M-sequences together. These M-sequences should be generated from irreducible primitive polynomials, and both polynomials should be a preferred pair. For design, the following process may be used:

[0106] Two M-sequences can be generated from the preferred pair polynomial. Two different shifts are used for both (m0 and m1). These are XORed. The sequences are BPSK modulated and repeated or truncated to satisfy all DMRS.

[0107] If the chosen length of the M-sequence is 31, which may be repeated, the following polynomial combinations may be used: octal values ​​45, 75, 67 in this order.

[0108] If g(x)=x5+x2+1,

[0109]

number

[0110] If g(x)=x5+x4+x3+x2+1,

[0111]

number

[0112] If g(x)=x5+x4+x2+x+1,

[0113]

number

[0114] Other irreducible primitive polynomials are not excluded (octal values ​​51, 37, 73). Initializations such as the following may be used, but other initializations may not be excluded:

[0115] x(0)=0,x(1)=0,x(2)=0,x(3)=0,x(4)=1

[0116] If the M-sequence length is 63 (for higher density DMRS), the following polynomial combinations may be used (octal values ​​are 103, 147, 155, respectively):

[0117] If g(x)=x6+x+1,

[0118]

number

[0119] If g(x)=x6+x5+x2+x+1,

[0120]

number

[0121] If g(x)=x6+x5+x3+x2+x+1,

[0122]

number

[0123] Other irreducible primitive polynomials are not excluded (octal values ​​133, 141, 163). Initializations such as the following may be used, but other initializations may not be excluded:

[0124] x(0)=0,x(1)=0,x(2)=0,x(3)=0,x(4)=0,x(5)=1,

[0125] The shifts in two sequences can be defined using the following equation: where s1, s2 are two sequences of length L, m0 and m1 are two shifts, and n ranges from 0 to L-1.

[0126]

number

[0127] The combining functions m0 and m1 may be used to indicate details to assist in channel decoding of the NR-PBCH, which may include information about polar encoding and / or decoding, and the beam ID.

[0128] Another option is that parameters such as the polynomial of the sequence and / or the shift of the sequence may be functions of the cell ID. This may allow for orthogonal DMRS between different cells. If the SS block ID is not indicated using DMRS but is known prior to decoding of the NR-PBCH, then those parameters may be functions of the SS block ID.

[0129] With regard to receiver processing, the following procedures may be used to detect information: the receiver may first acquire timing and frequency using NR-PSS / NR-SSS, the receiver may receive OFDM symbols of the NR-PBCH, the DMRS RE allocation may be a function of the cell ID and / or SS block ID, the DMRS RE mapping may be obtained based on the cell ID and / or SS block ID, the DMRS sequence may be a function of the cell ID and / or SS block ID, a local copy of the DMRS may be generated based on the cell ID and / or SS block ID, and the local copy of the DMRS may be used for channel estimation for the NR-PBCH and demodulation / decoding of the NR-PBCH.

[0130] The NR-PBCH can employ precoder rotation techniques to improve performance. In this case, the NR-PBCH reference signal, DMRS, and / or SS may or may not be precoded using the same precoder rotation pattern as the NR-PBCH data. Assuming the same precoder is used, precoder rotation can be applied in either the frequency domain or the time domain. Several different options that can be used for frequency-domain precoder rotation are detailed below.

[0131] A single precoder may be used for each NR-PBCH. A single precoder may be applied to all RBs, e.g., 24 RBs, the NR-PBCH data, and associated reference signals. A DMRS may be generated from a single sequence, e.g., an M, ZC, or Gold sequence, because longer sequences may improve detection performance. A DMRS may also be generated from two separate sequences separated by bandwidth.

[0132] A single precoder may be used per RBG. The RBs in the PBCH, along with associated reference signals, may be divided into multiple RB groups (RBGs), and a different precoder may be applied to each group. Note that using different precoders may increase frequency diversity and therefore improve performance. Typically, the RBGs vary from 1 to N, where N is the number of RBs in the NR-PBCH, in which case we return to the options above. The pattern may be known by the WTRU via signaling from the SS or predefined. Each RBG may use a different sequence, but it may be important to adjust the number of DMRSs and the sequence length to match each other. The sequence length should attempt to achieve optimal correlation properties, so that a particular sequence can span multiple RBGs.

[0133] A single precoder may be used per sub-RB. In an exemplary scenario, a precoder may be used per RE, subcarrier, or OFDM symbol for the PBCH. A predefined precoder rotation pattern may be used across REs, subcarriers, or OFDM symbols for the PBCH. One precoder may be used per DMRS. One DMRS group may be defined as a half RB, a partition of an RB, or an RE group (REG). An association between DMRS REs and data REs in the PBCH may be defined. This may also improve frequency diversity.

[0134] Precoder rotation may also be applied in the time domain. Several different options that may be used for time domain precoder rotation are detailed herein.

[0135] A single precoder may be applied for NR-PBCH transmissions. In this case, the single precoder is applied to all PBCH data and reference signals. A different precoder may be applied for each modulo(n) NR-PBCH transmission. In this case, a different precoder is applied for each NR-PBCH transmission modulo(n). For example, when n=2, the following may apply: NR-PBCH transmission (0) applies precoder (0), NR-PBCH transmission (1) applies precoder (1), NR-PBCH transmission (3) applies precoder (0), NR-PBCH transmission (4) applies precoder (1), etc. The rotation may allow different WTRUs to obtain improved performance for different NR-PBCH transmissions based on each WTRU's unique spatial and frequency domain channel characteristics.

[0136] In each of the above cases, when there are multiple precoders applied per NR-PBCH, a rotation pattern can be selected to maximize spatial and frequency diversity. In an open-loop approach, this rotation pattern can be predetermined and selected, for example, based on the spatial characteristics of the generated precoder beam. To maximize frequency-domain diversity, frequency-domain characteristics can also be considered when selecting a precoder pattern.

[0137] To use both NR-SS and the built-in DMRS for NR-PBCH demodulation, an indicator may be introduced that indicates to the WTRU whether NR-SS and the built-in DMRS can be jointly used for channel estimation and coherent combining for NR-PBCH demodulation. A quasi-coexistence (QCL) indicator may be introduced for initial access and NR-PBCH demodulation. When two signals are transmitted from two different antennas, the channels experienced by the two antennas may still have many large-scale characteristics in common. For example, the two signals may have the same or similar Doppler spread or shift, average delay, average delay spread, or average gain, and therefore may be used by the WTRU in setting parameters for channel estimation. However, when the two antennas are separated by distance, the signals from the two antenna ports may also differ in terms of large-scale characteristics. A QCL indicator may be used to indicate the long-term channel characteristics of various antenna ports and various reference signals. For example, NR-SS and DMRS dedicated to the PBCH may be assumed to be QCL even if they are not on the same antenna port. In multiple transmission point (TRP) (multi-TRP) transmissions, the DMRS dedicated to NR-SS and PBCH may not be assumed to be QCL depending on whether they are co-located. The QCL indicator may be indicated in the NR-SS signal. If message-based NR-SS is used, the QCL indicator may be carried by the synchronization payload. If sequence-based NR-SS is used, the QCL may be embedded in the NR-PSS or NR-SSS, or a combination of both. For example, different frequency and / or time relative offsets may be used to indicate the QCL. Various root indices or circular shifts of the ZC sequence may be used to indicate the QCL. Furthermore, various combinations of the X and Y components in the NR-PSS or NR-SSS may be used to indicate the QCL.Once the QCL is indicated to the WTRU, the WTRU can use the NR-PSS and / or NR-SSS together as a reference signal combined with the NR-PBCH-dedicated DMRS for channel estimation. QCL-assisted initial access and NR-PBCH demodulation can be performed. Such QCL parameters may include, but are not limited to, Doppler spread or shift, channel mean delay, channel mean delay spread, channel mean gain, beam correlation, and spatial correlation.

[0138] FIG. 12 is a flowchart 1200 illustrating an example of a supplemental access procedure and NR-PBCH demodulation assisted or aided by a QCL indicator. Demodulation of the NR-PBCH assisted by a QCL indicator is shown in FIG. 12. In this method, the QCL indicator is introduced to assist NR-PBCH demodulation. Depending on the value of the QCL, different configurations of channel estimation may be used for NR-PBCH demodulation. One exemplary method for NR-PBCH demodulation assisted by a QCL indicator is detailed below. The WTRU may search for an NR-SS signal (1202) and may detect NR-PSS and NR-SSS (1204). The received QCL indicator and / or the value of the QCL indicator may be checked. If the QCL indicates a first configuration, e.g., configuration 1 1208, the WTRU may perform channel estimation 1210 using both NR-SS and NR-PBCH-DMRS (1210). If the QCL indicates a second configuration, e.g., configuration 2 1212, the WTRU may perform channel estimation using only the NR-PBCH-DMRS (1214). The WTRU may demodulate the NR-PBCH signal and channel using the channel response estimated from either configuration 1 1208 or configuration 2 1212 (1216).

[0139] Multi-antenna techniques may be used for the transmission of the NR-PBCH. For example, two-port space-frequency block coding (SFBC) and two-port precoder cycling may be used as the multi-antenna technique for the NR-PBCH. For simplicity reasons, a single antenna port may be used. When multiple multi-antenna techniques are used for the NR-PBCH, information regarding the multi-antenna technique used for the NR-PBCH may be indicated to the WTRU. Such an indication may be carried by the NR-PSS and / or NR-SSS to indicate one or more multi-antenna techniques, or in one embodiment, to indicate the MIMO scheme or method used for the NR-PBCH. Both digital and analog beamforming techniques may be used. A hybrid digital and analog beamforming scheme may also be used.

[0140] Precoder cycling may be used as one of the multi-antenna techniques shown. Both open-loop and semi-open-loop methods may be used. A precoder using large-delay cyclic delay diversity (CDD) and / or small-delay CDD may be used. The precoder cycling pattern may be performed in time and / or frequency and may be predetermined and signaled to the WTRU. Both the NR-PBCH signal and the channel containing embedded DMRS within the NR-PBCH signal may use the same precoder set and the same precoder cycling pattern may apply. The gNB or TRP may perform digital beam sweeping in time and / or frequency. Digital beamforming using precoder cycling or SFBC may be combined with analog beamforming and beam sweeping for the NR-PBCH.

[0141] An exemplary precoder rotation design for the NR-PBCH is disclosed herein. NR-PBCH transmissions may be based on two antenna ports using precoder rotation. The transmissions on these two ports may have the same or different types of precoders and precoder schemes, such as open loop (including large delay CDD or small delay CDD) or semi-open loop.

[0142] In a semi-open loop, the gNB or TRP can apply a precoder, which may be expressed as W = W · W, where the wideband precoding matrix W represents the long-term statistics and the (narrowband) precoding matrix W represents the instantaneous channel conditions. In a semi-open loop PBCH scheme, the long-term precoding matrix W is fed back to the gNB from one or more WTRUs. This can actually define the set of DFT beams used for this WTRU and suggests the approximate direction of the WTRU. Note that this semi-open loop procedure may be effective for connected mode WTRUs. If a WTRU in a cell is located in a specific small area of ​​the gNB, a semi-open loop PBCH scheme may be applied, in which case W may be determined by the WTRU location. The gNB can then cycle through the narrowband precoding matrix W to determine the final precoder. The cycling pattern may be in the time and / or frequency domain.

[0143] A digital precoder or an analog beamformer may be used for W1, and a digital beamformer may be used for W2. One exemplary design may use W1 based on analog beamforming, e.g., DFT, and a digital precoder W2. Precoder rotation may be used for W2.

[0144] In another exemplary design, for example, DFT-based digital W1 and W2 may be used, and precoder rotation may be performed on W2 or on both W1 and W2.

[0145] In another exemplary design, for example, digital precoder codebook-based W1 and W2 may be used. Precoder rotation may be performed on W2 or on both W1 and W2. Precoder rotation may be performed on analog, digital beamforming or precoding, or a combination of the two.

[0146] FIG. 13 illustrates an example 1300 using SS blocks associated with different precoders. In open-loop CDD transmission of the PBCH, CDD coefficients may be applied at the subcarrier level or the RB level. The rotation pattern may be in the time and / or frequency domain. Because the PBCH is broadcast repeatedly over a specific time period, each PBCH message may be associated with a PBCH transmission pattern. FIG. 13 illustrates an example of four SS blocks 1302-1308 having the same content. Each SS block 1302-1308 may be associated with a different precoder 1310-1316 that directs the PBCH message in a different direction. In this example, SS1 1302 is associated with precoder 1 1310, SS2 1304 is associated with precoder 1 1312, SS3 1306 is associated with precoder 1 1314, and SS4 1308 is associated with precoder 1 1316. Each of precoders 1-4 1310-1316 is depicted and shown for illustrative purposes only. The quality of each selected precoder may be similar to or different from a conventional MIMO precoder for 4G. For example, a three-dimensional (3D) precoder may be used. In this way, the 3D can take into account the WTRU altitude in the vertical domain. Other precoders may support highly parallel antenna technologies. Existing MIMO precoding, e.g., 4G technologies, may be used. Existing codebooks may be used. For backward compatibility and / or flexible deployment scenarios, new codebooks may be added in addition to existing codebooks.

[0147] Figure 14 shows an example 1400 in which SS blocks are associated with different precoders that are shifted across different PBCH messages 1402, 1420, 1440, 1460. The association between precoders and SS blocks can be the same or different between different PBCH messages 1402, 1420, 1440, 1460. In one embodiment, the association can be shifted. Figure 14 shows an example illustrating how the association of precoders and SS blocks shifts with the PBCH messages 1402, 1420, 1440, 1460. Specifically, in the first PBCH message 1402, SS block i is associated with precoder i. Thus, precoder 1 1404 is associated with SS block 1 1406, precoder 2 1408 is associated with SS block 2 1410, precoder 3 1412 is associated with SS block 3 1414, and precoder 4 1416 is associated with SS block 4 1418. In the second PBCH message 1420, SS block i is associated with precoder i+1 mod 4, etc. Thus, precoder 2 1422 is associated with SS block 1 1424, precoder 3 1426 is associated with SS block 2 1428, precoder 4 1430 is associated with SS block 3 1432, and precoder 1 1434 is associated with SS block 4 1436. In message 3 1440, precoder 3 1442 is associated with SS block 1 1444, precoder 4 1446 is associated with SS block 2 1448, precoder 1 1450 is associated with SS block 3 1452, and precoder 2 1454 is associated with SS block 4 1456. In message 4 1460, precoder 4 1462 is associated with SS block 1 1464, precoder 1 1466 is associated with SS block 2 1468, precoder 2 1470 is associated with SS block 3 1472, and precoder 3 1474 is associated with SS block 4 1476. As described above in connection with FIG. 13, various precoding schemes may be used in FIG. 14 as well.Some precoding schemes may include nonlinear precoding (NLP) schemes, such as Tomlinson-Harashima precoding or vector perturbation. Other hybrid precoding schemes may include semi-dynamic or dynamic switching between linear precoding and NLP.

[0148] FIG. 15 is a diagram of transmit circuitry 1500 configured for an exemplary combination of analog beamforming and two-port cyclic delay diversity (CDD) for diversity. The digital beam sweeping scheme of FIG. 14 may be combined with analog beam sweeping. FIG. 15 illustrates an example of combining CDD with analog beamforming, which is directed to exploring greater diversity gain in the spatial, frequency, and time domains. FIG. 15 shows two RF chains: RF chain 1 1502 and RF chain 2 1504. RF chain 1 1502 circuitry may be configured to transmit 1510 at time t1 1506 using a first precoder. After a delay period, which may be implemented by, for example, a timer or clock circuitry 1510, a second transmission 1512 may be sent by RF chain 2 1504 using a second precoder. The second transmission may be sent at time t2 1508. The first transmission 1510 and the second transmission 1512 may partially or completely overlap in time, or may not overlap at all.

[0149] FIG. 16 is a diagram 1600 of an example combination of digital and analog beamforming shown in the time domain. Assume there are n1 patterns for the digital beam sweeping MIMO scheme and n2 patterns for the analog beam sweeping scheme. A total of n1·n2 combinations for cycling are possible. An example combination is shown in FIG. 14, where n1 = n2 = 2. Furthermore, in an alternative embodiment, where only n2 beam sweeps for the analog beams may be required while the digital beam sweeps simultaneously maintain the same frequency domain, as shown in FIG. 17, n2 beam sweeps for the analog beam sweeping may be performed in the time domain and n1 beam sweeps for the digital beam sweeping may be performed in the frequency domain. As shown in FIG. 16, the same digital precoders 1602 and 1604 may be used for the first and second transmissions. Two different analog beams 1606 and 1608 may be generated for the same transmissions. For the third and fourth transmissions, second digital precoders 1610 and 1612 may be used. The second digital precoders 1610 and 1612 may be the same digital precoder. Analog beam 1 1614 and analog beam 2 1616 may be different analog beams to achieve diversity.

[0150] Figure 17 is a diagram of an example combination of digital and analog beamforming in the time and frequency domains. In this embodiment, alternative analog beams are shown in the time domain and alternative digital beams are shown in the frequency domain. Referring to Figure 17, in a first transmission at a time, a second digital precoder 1702 is used at the same frequency as the first digital precoder 1704. At the same time, two identical analog beams 1706 and 1708 are transmitted. For a second transmission at a different time, two different digital precoders 1710 and 1712 are used with two identical analog beams 1714 and 1716.

[0151] FIG. 18 is a diagram of an example combination of analog beamforming and two-port space-frequency block coding (SFBC) for transmit diversity. Using a circuit configuration such as that shown in FIG. 18, transmission of the NR-PBCH can be based on one or more transmit diversity schemes, including a two-port SFBC scheme. In high frequency bands, for example, transmissions on each port may be associated with multiple antenna elements, and analog beamforming on each port may be used to further achieve diversity gain. FIG. 18 shows an example SFBC design combined with analog beamforming to achieve further diversity gain. As shown, symbols S0 1802 and S1 1804 are sent on antenna port 1 1810 via different subcarriers, subcarrier 1 1806 and subcarrier 2 1808, and symbols −S1* 1814 and S0* 1812 are sent on antenna port 2 1816 via different subcarriers, subcarrier 1 1806 and subcarrier 2 1808. In this example, diversity in the digital domain is achieved by inverting S1 1804, S0 1802, and S0*1814, -S1*1812. Thus, the bit streams provided to RF chain 1 1818 and RF chain 2 1820 are reversed. In the analog domain, RF chain 1 1818 and RF chain 2 1820 can each use a different beamforming technique. In that case, there can be different beam shapes 1822 and 1824 transmitted to the receiver.

[0152] In one embodiment, analog beamforming circuitry can adjust the beam direction and beam width for each of the antenna ports 1810 and 1816 in the SFBC scheme 1800. The control of the analog beamforming may rely on prior knowledge of the WTRU geographic distribution. The WTRU geographic distribution or beam position profile may be provided via uplink signaling or grant-free access.

[0153] Communications at frequencies above 6 GHz in 5G NR are likely to rely on highly directional transmission and reception. The first step to establishing a reliable link is the so-called initial access procedure, which includes cell search, PBCH transmission, and RACH procedures. Procedures associated with current 4G LTE systems may be used as a basis. However, because LTE is limited to frequencies below 6 GHz, directional transmission and reception are not required and are not incorporated into these initial access procedures. Therefore, new initial access procedures may need to be designed that take into account the additional complexities associated with directional communication systems. Because each transmit and receive beam may cover a limited angular interval, a procedure may need to be established to identify beam pairs that can be used for communication. This procedure may be performed by beam sweeping at the transmit and / or receive points. The addition of the beam sweep procedure may add significant complexity, and power consumption, overhead, latency, etc. may need to be taken into account.

[0154] A conventional beam sweeping procedure may involve the TRP and WTRU "testing" all combinations of beam pairs and selecting the beam pair that may provide the best performance. The "testing" may be performed by the TRP transmitting a known sequence on a given beam while the WTRU receives the given beam and measures the resulting SINR. The measurements may be repeated for all possible beam pairs, and the beam pair that returns the maximum SINR value is selected. The framework for this type of procedure is defined in the TRP for 5G NR as shown in Figure 19.

[0155] 19 is an example TRP transmission structure 1900 that may be used for initial access. The transmission of the initial access based signal occurs within the synchronization signal burst time T ssb Occurred during 1902 and T of SS period 1904 p Repeat every T seconds to accommodate the beam sweep procedure. ssb1902 may be composed of an integer number of OFDM symbols 1906 and 1908, e.g., each OFDM symbol is transmitted over an OFDM symbol time T sym 1910. Using this basic framework, the WTRU can further sweep through the set of beams and ultimately determine the beam pair to use for subsequent communications. In this way, at any time T p In seconds, it may be possible to cycle through and test multiple beams during initial synchronization, which can provide significant performance improvements without having to perform additional testing after synchronization.

[0156] One simple way to design a complete beam sweeping procedure using the framework defined in FIG. 19 is to perform an exhaustive search over all available beam pairs at the TRP and the WTRU, as shown in FIG. 20.

[0157] FIG. 20 illustrates an exemplary single-stage exhaustive search beam sweeping procedure 2000. In FIG. 20, each SS burst 2002, 2004, 2006 may consist of N OFDM symbols, each symbol transmitting a single beam, with the N beams covering the entire angular range of the TRP 2008. As also illustrated, the WTRU 2010 receives from a single beam for the entire SS burst; therefore, a complete beam sweep requires M SS bursts 2012, 2014, 2016 to test all possible beam pairs. Note that to address signal jamming at the WTRU 2010, there are likely to be multiple receive arrays. For example, an array could be on each side of a rectangular device. If this is the case and each array supports M beams, then the total number of WTRU beams, and therefore the total number of SS bursts for a complete beam sweep, is four. As previously discussed, system overhead, access latency, and overall power consumption are concerns for the initial access procedure. These concerns are articulated herein in terms of overhead, latency, and power consumption. With regard to overhead, each OFDM symbol used for synchronization is unavailable for other purposes, such as data transmission. This can be a concern for a large N. The duration of the entire procedure may be viewed as additional overhead relative to the reduced time that could be used for communication. With regard to latency, one of the things that provides an improved user experience is the ability to quickly establish a communication link. In this sense, a large M, further coupled with multiple arrays to attempt to suppress interference, can significantly increase access time. Power consumption is another concern, and generally speaking, low power consumption is desirable. Low power consumption is particularly desirable in a WTRU, since the WTRU is typically a battery-operated device. Each beam pair measurement requires WTRU power, and therefore, limiting the number of beam pair measurements may be used to reduce power consumption.

[0158] FIG. 21 is an example of multi-stage WTRU hierarchical beam sweeping 2100. An alternative to the single-stage exhaustive search beam sweeping procedure shown in FIG. 20 is the multi-stage layered approach 2100. The search can begin with a wide beam covering a relatively large angular region in the first stage, then progressively reduce the angular search space and width of the beam used in subsequent stages. This progressive reduction can be applied to the TRP only, the WTRU only, or both the TRP and WTRU simultaneously. For illustrative purposes, an example of three-stage layered WTRU beam sweeping is shown in FIG. 21. In this example, the WTRU 2102 uses four arrays, each covering its angular region using 12 beams. From a latency perspective, an exhaustive beam sweeping procedure may require 4×12=48 SS bursts. The three-stage 2104-2108 procedure shown may require 4+4+3=11 SS bursts 2110-2120. Furthermore, from a power consumption perspective, the exhaustive beam sweeping procedure requires 48N measurements, while the current three-stage procedure requires only 11N measurements to be performed. In either case, this is a savings of approximately 77%. The following disclosure describes this procedure in more detail. For all stages 2104-2108, the TRP 2122 transmits N beams for each SS burst 2110-2120 over N OFDM symbols. The WTRU 2102, on the other hand, operates differently over time. In the first stage 2104, the WTRU 2102 receives using a single quasi-omni-beam for array 2124 for each SS burst. In the second stage 2106, the WTRU 2102 receives from four wide beams 2126 from the array that yielded the highest SINR from stage 1 2104. In the third stage 2108 , the WTRU 2102 receives from three narrow beams 2128 spatially contained within the wide beam that yielded the highest SINR from stage 2 2106 .

[0159] An additional example using multi-stage TRP hierarchical beam sweeping is shown in FIG. 22. Note that FIG. 22 also illustrates an embodiment in which multi-stage TRP / WTRU hierarchical beam sweeping is possible because the WTRUs can be hierarchical. For these cases, the exemplary procedure is as follows: In the first stage 2202, the TRP 2204 transmits from four wide beams for each SS burst 2208-2210 over four OFDM symbols. Meanwhile, in the first stage 2202, the WTRU 2206 receives from M beams using a single beam for each SS burst 2208-2210. In the second stage 2212, the TRP transmits from N narrow beams for each SS burst 2214-2216 over N OFDM symbols. In the second stage 2212, the WTRU 2206 has three options 2214-2218. In a first option 2214, the WTRU 2206 receives from M beams, using one beam per SS burst, but the WTRU 2206 may only measure TRP narrow beams that are spatially contained within the TRP wide beam detected in the first stage 2202. In a second option 2216, to further reduce power consumption, the WTRU 2206 may receive from only the one WTRU beam that resulted in the highest SINR measurement from the first stage 2202. In a third option 2218, to increase SINR from directional gain, the WTRU may use a hierarchical approach and receive from a set of narrow beams that are spatially contained within the detected WTRU 2206 wide beam from the first stage 2202.

[0160] For the first two options 2214-2216, assuming three narrow TRP beams per wide beam, the number of beam pair measurements required is 4M + 3M for option 1 and 4M + 3 for option 2. This compares to the number of measurements required for a single-stage coverage procedure, where the number of measurements required is 12M. This results in savings of approximately 42% and 60%, respectively. The third option 2218 combines the TRP 2204 and WTRU 2206 hierarchical beam sweeps. In this case, the number of measurements required is 4M + 3M. narrow In this case, M=4 and Mnarrow = 3, the number of measurements required is 25. In this case, narrower beams are used in stage 2 2212, allowing for additional array gain associated with narrower beams compared to option 1 2214 and option 2 2216. A single stage exhaustive comparison for this option would require 12 x 12 = 144 measurements, so this third option 2218 provides a savings of approximately 83%.

[0161] Another aspect of the initial access procedure to consider is the amount of interference seen by the WTRU from other TRPs. The multi-stage procedure, which was primarily used to reduce latency, power consumption, and overhead, may be further modified to also address interference issues. The main idea to reduce interference is to leverage the use of multiple stages, where information from earlier stages can be used in later stages to filter and potentially "turn off" certain TRP beams.

[0162] Figure 23 shows an example of such an approach, called selective beam sweeping, combined with a multi-stage TRP / WTRU hierarchical beam sweeping procedure. A general description of this procedure is detailed as follows: In the first stage 2302, a TRP 2304 selects N W N for each SS burst 2308-2310 over OFDM symbols W In the same stage 2302, the WTRU 2312 transmits from M wide beams 2306, using one beam per SS burst. W In the second stage 2316, the TRP 2304 receives from the selected LN N transmits from only narrow beams 2318, where L is the total number of wide beams detected by all WTRUs, and N N is the number of narrow beams in each wide beam. The TRP 2304 can repeat transmission for each SS burst 2318-2322.

[0163] The TRP can learn or acquire information about the detected wide beams directly from the WTRU via uplink using the beam pairs from the first stage, or indirectly from an anchor TRP to which the WTRU is already connected. The WTRU can learn or acquire information about the detected wide beams directly from the WTRU via uplink using the beam pairs from the first stage, or indirectly from an anchor TRP to which the WTRU is already connected. N It can be received from narrow beams.

[0164] The procedure shown in FIG. 23 combines TRP hierarchical beam sweeping, WTRU hierarchical beam sweeping, and TRP selective beam sweeping to maximize SINR while simultaneously reducing power consumption, latency, and overhead. Regarding SINR improvement due to reduced WTRU interference from “other” TRPs, it should be noted that this method may be advantageous when WTRU density is low and / or WTRUs are unevenly distributed. As an example, consider a situation where all WTRUs are concentrated in a specific geographic area within the TRP coverage area. For example, this may be the case at a sporting event or concert. In this case, each WTRU accesses the TRP using a similarly directed TRP beam, and thus, once this is learned by the TRP, the TRP does not need to transmit on a specific beam. It should also be noted that this embodiment, in addition to reducing interference, can provide power consumption savings at the TRP.

[0165] The benefits of the above procedure can also be seen empirically through system simulations. FIG. 24 shows SINR results 2400 from four different beam sweeping procedures, three of which are repeated with a non-uniform WTRU distribution to demonstrate the TRP selectivity sweeping performance gain. The results of the simulated procedures are summarized herein. One result shown involves a single-stage beam sweep 2402. Because a second stage is required to activate the TRP selectivity beam sweeping, the single-stage beam sweeping can be a single-stage simulation performed with only a uniform WTRU distribution. The performance of the single-stage beam sweep 2402 is substantially identical to the two-stage TRP selectivity beam sweeping procedure with a uniform WTRU distribution. Therefore, they are both labeled 2402.

[0166] In the two-stage TRP selective beam sweeping 2402, there is no hierarchical sweeping, and as described above, the performance is substantially identical to the single-stage procedure above when the WTRUs are uniformly distributed. When the WTRUs are non-uniformly distributed, SINR gains based on reduced interference levels can be realized. The case of two-stage selectivity non-uniform 2408 is shown for comparison.

[0167] Another result shown is a two-stage TRP hierarchy selective beam sweep 2404. There is an overall gain over the above procedure based on the TRP hierarchy approach using narrower beams in the second stage. There is also a gain based on reduced interference from TRP beams that are turned "off" when WTRUs are also unevenly distributed. The case of two-stage selective TRP hierarchy uneven 2410 is shown for comparison.

[0168] Another result is two-stage TRP / WTRU hierarchical selective beam sweeping 2406. There is additional gain based on adding a WTRU hierarchical approach, again using narrower beams in the second stage. There is also gain based on reducing interference from TRP beams that are turned "off" when WTRUs are also unevenly distributed. The case of two-stage selective TRP / WTRU uneven 2412 is shown for comparison.

[0169] FIG. 25 shows an alternative form 2500 of the TRP transmission structure shown in FIG. 19. As shown in FIG. 25, the defined SS bursts 2502-2508 and SS period 2510 are still retained. In this case, a single SS burst 2502-2508, still occupying multiple OFDM symbols, is assumed to be transmitted in a single beam direction. SS bursts 2502-2508 are repeated every Tp seconds in SS period Tp 2510, as shown previously, but in this case, instead of repeating the same beam pattern, a different beam direction is selected for each SS burst. After N SS bursts, the pattern repeats. Thus, in this case, a complete beam sweep will take a minimum of N SS bursts time, depending on how the WTRU beam sweeping is implemented.

[0170] A simple full beam sweeping procedure using the framework defined in Figure 25 can be performed by performing an exhaustive search across all available TRP and WTRU beam pairs. This procedure 2600 shown in Figure 26 is similar to the procedure shown in Figure 20, except that the roles of the WTRU and TRP are switched with respect to beam sweeping ordering. The TRP 2602 transmits one of N beam directions during SS bursts 2604-2608, and the WTRU 2610 cycles through all M beam directions during each SS burst 2604-2608. In this process, a full beam sweep requires N SS burst times to complete.

[0171] General observations may apply to cell-center WTRUs. In general, cell-center WTRUs may likely require less antenna gain than cell-edge WTRUs. This is likely true during and before the completion of the initial access procedure and to enable successful data transfer. Furthermore, note that multiple RF chain transmissions are easier to perform on a TRP than on a WTRU for reasons such as cost and power. With these observations in mind, a beam-sweeping procedure may be performed based on the transmission structure shown in FIG. 25. The procedure may reduce access latency and save processing power for cell-center WTRUs, while simultaneously allowing cell-edge WTRUs to gain access. This procedure is shown in FIG. 27.

[0172] Figure 27 is an example of a single-stage multi-RF chain TRP beam sweep 2700. In the example shown in Figure 27, two RF chains 2702-2704 are used in the TRP for the initial access procedure. The first RF chain 2702 is N N N narrow beams 2706 are used to cover the TRP serving area, and the second RF chain 2704 W N wide beams 2708 are used to cover the same TRP serving area, where N W <N N One or more WTRUs 2710 can receive from all M beams during each SS burst 2712-2722. This configuration allows cell-center WTRUs to complete the initial access procedure with reduced latency compared to cell-edge WTRUs. The procedure is described in more detail as follows: The first TRP RF chain 2702 receives N SS bursts 2712-2716 for each SS burst 2712-2716. N The beam sweep period is N N The second RF chain 2704 receives N bursts for each SS burst 2718-2722. W The beam sweep period is N W In one embodiment, N W <N NRF chains 1 and 2 may use the same, partially overlapping, or completely different circuit configurations. On the WTRU side, the WTRU cycles through all M beams during each SS burst 2724-2730. The cell center WTRU cycles through N W The cell-edge WTRU can determine the beam pair after N SS bursts. N The WTRU can determine the beam pair after the SS burst. The WTRU can decide to search for a wide TRP beam or a narrow TRP beam based on various criteria, such as information from the anchor TRP or initial signal power measurements.

[0173] MIMO and multi-beam transmission may be enabled for initial access, and in one embodiment, grant-free transmission may be enabled for MIMO and beamforming for PBCH and subsequent DL transmissions. At least one set of beamforming parameters may be provided, determined, configured, and / or known, for example, by a specification. The configuration may be provided and / or transmitted, for example, by the gNB, via signaling, such as broadcast or dedicated signaling. The configuration may be received by the WTRU.

[0174] A precoder may be used herein as a non-limiting example of a beamforming parameter. Some other examples include an antenna port, e.g., a CSI-RS port, a set of antenna ports, a beam ID or a set of beam IDs, etc. In the embodiments and examples described herein, any other beamforming parameter may be used in place of a precoder and still be consistent with the embodiments herein.

[0175] The WTRU may select at least one precoder, e.g., W1 or W2, from a set of precoders. The WTRU may select a first precoder from a first set of precoders. The WTRU may select a second precoder from a second set of precoders. The first and second sets may be the same or different. The WTRU may select a precoder that may be preferred or recommended. The WTRU may signal or indicate its selection of the at least one precoder, e.g., to the gNB.

[0176] The WTRU may select a precoder for a broadcast transmission for a broadcast channel, such as a PBCH. The WTRU may use a first precoder for a first reception of the broadcast channel. The WTRU may determine or know the first precoder before use. The first precoder may be a defined precoder that may be known by the WTRU.

[0177] The WTRU may determine the first precoder from at least one synchronization channel, e.g., from at least one of the time and / or frequency positions, e.g., relative positions, of the first and second synchronization channels, or the payload associated with the synchronization channel, or the sequence of the synchronization channel.

[0178] The WTRU may use a first precoder, e.g., until instructed to use a different precoder. The WTRU may indicate a precoder, e.g., a preferred precoder, e.g., for a broadcast channel. The WTRU may indicate a precoder to the gNB. The WTRU may indicate a precoder, e.g., in grant-free access, which the WTRU may make before or without establishing an RRC connection. The WTRU may indicate a precoder, e.g., in grant-free access, which the WTRU may make before or without establishing an RRC connection with the gNB.

[0179] Grant-free access may be a transmission that uses time and / or frequency resources without a grant, e.g., an explicit grant. Grant-free access may be or include random access, such as two-step or four-step random access. Grant-free access may be or include one-step transmission or one-step random access, e.g., message 1 or only message 1 of a random access procedure.

[0180] Resources and / or preambles that may be used for grant-free access may be configured via a broadcast channel or system information. The grant-free access may include transmission of at least one of a preamble, control information, and / or a data payload. The WTRU may use the preamble, control information, and / or data payload to indicate a selected precoder. The WTRU may expect a response or acknowledgment for the grant-free access and / or for information carried by the grant-free access. Alternatively, the WTRU may not expect a response or acknowledgment for grant-free access, such as grant-free access that may be used to indicate beamforming parameters.

[0181] The gNB may receive the precoder indicator, for example, from the WTRU. The gNB may receive the precoder indicator via grant-free access. The gNB may receive the precoder indicator for a broadcast channel. The gNB may use the precoder indicator for semi-open-loop MIMO applied to the broadcast channel.

[0182] The gNB may receive a first precoder indicator from the first WTRU and a second precoder indicator from the second WTRU. The gNB may determine a precoder to use for, for example, a broadcast channel based on the first precoder indicator and the second precoder indicator. The gNB may use the determined precoder for, for example, transmission of the broadcast channel.

[0183] In an example, the determined precoder may be a compromise between the first precoder and the second precoder. In another example, the first precoder may be used sometimes and the second precoder may be used sometimes. For example, the gNB may cycle through a set of indicated precoders it receives from a set of WTRUs that may provide beacons on the same beam or set of beams or from the same or similar direction. The gNB may alternate between the first indicated precoder and the second indicated precoder.

[0184] The gNB may indicate beamforming parameters such as a precoder in response to the grant-free access. The response may be via DL control information (DCI) or a DL data channel, which may have an associated DCI that may indicate resources for the DL data channel. The DCI may use a common RNTI. The WTRU may monitor the common RNTI to receive the DCI and / or DL ​​data.

[0185] A synchronization (sync) channel or set of synchronization channels may be used to indicate a precoder that may be used for a broadcast channel. A gNB can modify the synchronization channel or set of synchronization channels when it modifies the precoder for a broadcast channel. The modification may be to the synchronization channel sequence, the time and / or frequency position, using, for example, relative positions, of the first and second synchronization channels, and / or the payload associated with the synchronization channel.

[0186] The first broadcast channel may be used to indicate a precoder and / or a precoder rotation pattern that may be used for the second broadcast channel. The indication may be provided within a payload carried by the first broadcast channel.

[0187] The WTRU may use the indicated precoder and / or precoder rotation pattern for reception of a channel, such as a secondary broadcast channel. The indication may be provided by the gNB. The WTRU may use the selected precoder for reception of a channel, such as a broadcast channel or a secondary broadcast channel. The selected precoder or precoder rotation pattern may be one indicated by the WTRU, for example, in grant-free access. The selected precoder or precoder rotation pattern may be one indicated by the WTRU, for example, to the gNB.

[0188] In an example, a WTRU may receive a channel, such as a broadcast channel, using a first precoder. The WTRU may use a second precoder, for example, to receive a channel when reception is unsuccessful with the first precoder or to receive a secondary broadcast channel.

[0189] The first or second precoder may be a precoder selected by the WTRU. The WTRU may use the first or second precoder after indicating the first or second precoder (e.g., to the gNB and / or in grant-free access). The second or first precoder may be an initial, precoder, a configured, or an indicated precoder. The WTRU may use the grant-free transmission to feed back at least one of a precoder, e.g., W1, for long-term statistics; a precoder, e.g., W2, for short-term statistics or instantaneous channel conditions; an analog beamformer, e.g., a beam ID or a set of beam IDs; a beam pair link or a set of beam pair links; an antenna port or virtual antenna port, e.g., a CSI-RS port or a set of CSI-RS ports; a beam position profile; an ACK / NACK in response to a beam; or a WTRU beam correspondence or reciprocity.

[0190] A length-72 DMRS sequence can be generated for time-repeated sequence DMRS. This sequence can be mapped to 72 DMRS REs in the first OFDM symbol and copied onto the second OFDM symbol. If QPSK modulation is used, a length-144 sequence can be generated and converted to 72 QPSK symbols and mapped to all REs in each OFDM symbol. If BPSK modulation is used, a length-72 sequence can be generated and mapped to all REs in each OFDM symbol. In this configuration, only one sequence is generated, which can carry the SS block time index (SBTI). The terms SS block ID, SS block index, and SS block time index can be used interchangeably. Different methods of SBTI indication are disclosed. For the second OFDM symbol, each DMRS RE is repeated in time, so residual CFO estimation can be performed and corrected. However, shortening the sequence length can degrade SBTI detection performance. Similar to using channel estimation, performing pre-equalization on these symbols is difficult outside the NR-PSS / NR-SSS bandwidth. This can cause the receiver to perform non-coherent detection and thus degrade performance.

[0191] For example, in a frequency-specific sequence DMRS configuration, a length 72 DMRS sequence may be generated (S(1:72)). This is mapped to the central 12 RBs on both OFDM symbols of the NR-PBCH. This same sequence is also copied to the remaining 12 RBs (outside the SS bandwidth). This can be done in several different ways.

[0192] Figures 28 and 29 illustrate frequency repetition or frequency swapped repetition 2800, 2900. In Figure 28, bits S(19:36) 2802-2804 are found twice on PBCH1. The same is true for bits S(1:18) 2808-2810. A similar ordering may be found on PBCH2. In this example, bits S(55:72) 2814-2816 are repeated twice along with bits S(37:54) 2818-2820. Figure 28 provides the repetition in the frequency domain rather than the time domain.

[0193] Figure 29 is another example 2900 of frequency repetition. In Figure 29, PBCH1 2902 carries bits S(19:36) 2906 between bits S(1:18) 2904 and bits S(1:18) 2908. Adjacent bits S(1:18) 2908 are another instance of bits S(19:36) 1910. On PBCH2 2912, bits S(55:72) 2916 are found between bits S(37:54) 2914 and bits S(37:54) 2918. Adjacent bits S(37:54) 2918 are bits S(55:72) 2920. Frequency swapping can result in greater diversity. It may also be possible to perform frequency and / or time swap repetition in different ways.

[0194] Some example embodiments 3000, 3100 are shown in Figures 30 and 31. In Figure 30, on PBCH1 3002, bits S(19:36) 3006 are between bits S(55:72) 3004 and bits S(1:18) 3008. Adjacent to bits S(1:18) 3008 are bits S(37:54) 3010. PBCH2 3012 includes bits S(55:72) 3016 positioned between bits S(19:36) 3014 and bits S(37:54) 3018. Bits S(37:54) 3018 are positioned adjacent to bits S(1:18) 3020. In this manner, redundancy is provided in the time domain and frequency interleaving is applied.

[0195] Figure 31 is an example similar to the example of Figure 30. In Figure 31, on PBCH1 3102, bits S(19:36) 3106 are located between bits S(37:54) 3104 and bits S(1:18) 3108. Adjacent to bits S(1:18) 3108 are bits S(55:72) 3110. PBCH2 3112 includes bits S(55:72) 3116 located between bits S(1:18) 3014 and bits S(37:54) 3118. Bits S(37:54) 3118 are located adjacent to bits S(19:36) 3120. Figure 31 reverses the bit order of Figure 30 such that the higher numbered bits 3004 and 3014 of Figure 30 are moved to opposite frequency ends 3110, 3120 of Figure 31. This is similar for bits S(37:54) 3002 and S(1:18) 3020 of Figure 30 and S(37:54) 3104 and S(1:18) 3114 of Figure 31.

[0196] A potential feature of these configurations is that only the central REs may need to be decoded to find SBTI. When good channel conditions are known based on NR-PSS / NR-SSS detection, these configurations can reduce SBTI detection complexity. In this configuration, NR-PSS / NR-SSS may be used for pre-equalization for coherent detection of the sequence carried on the central RBs. Non-coherent detection may need to be performed for RBs outside the NR-SS bandwidth, which may be combined with coherent detection of the central RBs.

[0197] NR-PSS and NR-SSS may occupy only N REs, e.g., N=127 REs in the center, instead of all 144 REs in 12 RBs. Therefore, good channel estimation can be performed for only 31 REs in one OFDM symbol or a total of 62 REs in two OFDM symbols. Extrapolation of channel estimation may not be performed very well. Also, this method may not allow subcarriers to be repeated in time, and therefore residual CFO estimation is not possible. Therefore, modified methods may be used additionally or in combination.

[0198] In one embodiment, a length-62 DMRS sequence may be mapped to the central 12 RBs on the subcarriers overlapping with the NR-PSS / NR-SSS, with a repeated sequence mapped to the remaining 12 RBs. Figure 32 illustrates a length-62 sequence with repetition in frequency. An exemplary diagram of PBCH1 3202 and PBCH2 is shown. The areas marked with ×s 3204-3216 are areas where payload may be transmitted. The shaded area in Figure 32 represents the PBCH DMRS REs and sequences, but is not the payload. DMRS subcarriers 3204-3216 contain symbols repeated in the second OFDM symbol of the NR-PBCH on the DMRS REs. Due to asymmetry, in each OFDM symbol, the higher band (outside the SS band) has two such REs, and the lower band (outside the SS band) has three such REs. These may be used for CFO compensation and channel estimation. In regions outside the NR-SS bandwidth, these subcarriers may be more evenly distributed. This length-62 scheme may also have various configurations, such as time and frequency swapping, as shown in Figures 28-31. As shown in Figure 32, shaded areas 3218-3236 may carry a sequence of PBCH DMRSs. PBCH2 includes payload elements 3240-3252 and bits used for DMRSs 3254-3270. In this manner, the payload elements may be interleaved with the DMRSs.

[0199] All of the schemes described above have a single sequence containing information about the SBTI. Therefore, using these DMRSs for channel estimation is possible only after the SBTI is decoded. Therefore, only information within the SS bandwidth can be used to coherently decode the SBTI. To overcome this problem, another design is disclosed. In this design, two sequences are used. The first sequence is mapped onto the DMRS REs of the first OFDM symbol of the NR-PBCH. The second sequence is mapped onto the DMRS REs of the second OFDM symbol of the NR-PBCH.

[0200] The first sequence is generated using a cell ID. For convenience, this is referred to as the reference DMRS. The cell ID may be determined from NR-PSS / NR-SSS detection. The cell ID may be used to determine the first sequence. Channel estimation may be performed for those REs using knowledge of the sequence. These channel estimates may be used to pre-equalize the DMRS REs or subcarriers. The second sequence depends on the SBTI alone or in conjunction with the cell ID and the SBTI. Because this sequence is used to indicate the SBTI, the term "marked DMRS" is used to refer to this sequence as used herein. After coherently detecting the second sequence, the SBTI may be decoded. This sequence may be a function of several variables.

[0201] In another variation of the same concept, a known base sequence may be generated. This base is modified using a cell ID to generate a sequence for a reference DMRS. The sequence may also be modified using SBTI to generate a sequence for a beacon DMRS. The reference DMRS is used to perform pre-equalization and coherently estimate the beacon DMRS, thus detecting the SBTI.

[0202] These modifications as a function of SBTI may be performed using some of the following: different initialization of a linear feedback shift register (LFSR) for the gold code M-sequence, frequency or circular shift of the gold code M-sequence, gold sequence frequency or circular shift, circular shift, and performing scrambling on the original sequence.

[0203] Once the NR-PSS and NR-SSS are detected, they may be used as known sequences for channel estimation and pre-equalization for the center RBs, and it may be possible to use the reference DMRS only for RBs (or subcarriers) not occupied by the NR-PSS / NR-SSS. Thus, the indicator DMRS is mapped onto the first and second OFDM symbols of the NR-PBCH in a bandwidth that overlaps with the NR-PSS and NR-SSS. This can increase the length of the sequence used for the indicator DMRS and improve the performance of the indicator DMRS.

[0204] In the above design, the first sequence is mapped onto the first OFDM symbol of the NR-PBCH, and the second sequence is mapped onto the second OFDM symbol. It may also be possible to alternate the two sequences within one OFDM symbol. Thus, the sequences are mapped onto the DMRS REs of alternating OFDM symbols of the NR-PBCH. This can improve channel estimation performance using one of the sequences. It can also improve the diversity of the second sequence and, therefore, SBTI detection. This pattern is shown in Figure 33, which shows the NR-PBCH DMRS distribution of two sequences in a comb pattern.

[0205] Figure 33 is an example 3300 of NR-PBCH DMRS distribution for two sequences in a comb pattern. In Figure 33, r1 3304-3310 indicate REs to which reference DMRSs are mapped, and r2 3312-3316 indicate REs to which indicator DMRSs are mapped. With reference to NR-PBCH1 3302, r1 3304-3310 are distributed among r2 3312-3316. With reference to NR-PBCH2 3318, r1 3320-3324 are distributed among r2 3326-3332.

[0206] This comb pattern may be used to transmit the reference DMRS and the beacon DMRS. In one design, the reference DMRS sequence may be generated using only the cell ID, which may be modified using the SBTI to generate the beacon DMRS sequence.

[0207] Another option is to generate a known base sequence, which is modified using a cell ID to generate a sequence for the reference DMRS, and which is also modified using the SBTI to generate a sequence for the tagged DMRS.

[0208] Similar to the simple pattern case, further modifications as a function of SBTI may be performed with one or more of different initializations of a linear feedback shift register (LFSR) for the gold code M-sequence, frequency or circular shift of the gold code M-sequence, gold sequence frequency or circular shift, circular shift, and / or scrambling on one or more original sequences.

[0209] As in the simple pattern case, NR-PSS and NR-SSS may be used for channel estimation and pre-equalization for the center RB. It is possible to use the reference DMRS only for RBs (or subcarriers) not occupied by NR-PSS / NR-SSS. Therefore, the indicator DMRS is mapped onto the first and second OFDM symbols of the NR-PBCH in the bandwidth overlapping with NR-PSS and NR-SSS. This can increase the length of the sequence used for the indicator DMRS and thus improve the performance of the indicator DMRS.

[0210] Short LFSR gold sequences can be implemented using shift registers. In this way, shift registers of different lengths can be used to generate gold sequences. For example, if a short length LFSR of length 7 is used, then: c(n)=(x1(n)+x2(n))mod2 x1(n+7)=(x1(n+4)+x1(n))mod2 x²(n+7)=(x²(n+1)+x²(n))mod²

[0211] One or both M-sequences may be initialized with the states x(0) = 0, x(1) = 0, x(2) = 0, ..., x(5) = 0, x(6) = 1. If only one LFSR is initialized with 0001, the other LFSR may be initialized using the SS block time index or cell ID or a combination of both.

[0212] Longer LFSR Gold sequences may be used in addition or in combination. Longer LFSR Gold sequences may also be generated using longer shift registers, and when selecting the output, a shift (Nc) may be used to select the portion of the gold sequence of the desired length. c(n)=(x1(n+N c )+x2(n+N c ))mod2 x1(n+31)=(x1(n+3)+x1(n))mod2 x2(n+31)=(x2(n+3)+x2(n+2)+x2(n+1)+x2(n))mod2

[0213] Nc may be defined as an integer, for example, Nc=1600.

[0214] Very long LFSR gold sequences, for example of length 64, may also be generated by a longer shift register, and in selecting the output, the shift (Nc) may be used to select the portion of the gold sequence of the desired length. c(n)=(x1(n+N c )+x2(n+N c ))mod2 x1(n+63)=(x1(n+1)+x1(n))mod2 x2(n+63)=(x2(n+38)+x2(n+13)+x2(n+1)+x2(n))mod2

[0215] In this example,

[0216]

number

[0217] where Nc can be a much larger integer and can be determined experimentally to find good correlation sequences.

[0218] Any of the above sequences may be scrambled before modulation (BPSK / QPSK). The scrambling code may be generated from an LFSR of similar length.

[0219] A cyclic shift may be applied to either Gold sequence after modulation (BPSK / QPSK).

[0220] The circular shift is

[0221]

number

[0222] where m=0, 1, ..., M-1 and i is the shift index. In this example, seq is the original modulated sequence and seq CS is a sequence with a circular shift.

[0223] Modulation is used for the sequences, and all of the above sequences can be BPSK or QPSK modulated.

[0224] When using BPSK, r(m) = (1-2·c(m)), where:

[0225]

number

[0226] Using QPSK, each two bits can be combined into one symbol as follows:

[0227]

number

[0228] however,

[0229]

number

[0230]

number

[0231] Bits that are a distance apart can be combined into one symbol as follows:

[0232]

number

[0233] however,

[0234]

number

[0235] In an embodiment, NR-PBCH DMRS time block ID indication / detection may be implemented. Different initializations of the M-sequence LFSR may be performed.

[0236] For example, c(n)=(x1(n)+x2(n))mod2 x1(n+7)=(x1(n+4)+x1(n))mod2 x²(n+7)=(x²(n+1)+x²(n))mod² Consider the gold code defined by

[0237] x1 is the first M-sequence and x2 is the second M-sequence that generates the gold code. The LFSRs for generating one or both of the m-sequences x1, x2 used to generate the gold code can be initialized using the SBTI or cell ID or a combination of both, or using a combination of many more variables such as the RNTI, slot number, cell ID, half frame, etc.

[0238] Various examples of these initial settings are listed below.

[0239] Option 1:

[0240]

number

[0241] Option 2:

[0242]

number

[0243] where x is a known integer. Option 3:

[0244]

number

[0245] where x is L lfsr An integer smaller than -1-10.

[0246]

number

[0247] Option 4:

[0248]

number

[0249] Option 5 may be a more generalized version of option 4.

[0250]

number

[0251] where x1 to x5 can be experimentally determined to have the best correlation properties. Still other options are possible.

[0252] It may also be possible to generate two different gold sequences using two different initializations, for example, a first shift resulting in a reference DMRS may be used for pre-equalization, and another shift resulting in a beacon DMRS may be used to indicate SBTI.

[0253] If only one sequence is used, partially coherent / partially non-coherent detection can be performed: different hypotheses of the gold sequence are generated (using different initializations of the M-sequence) to detect SBTI at the receiver.

[0254] A frequency or circular shift of the individual M-sequences may be applied. c(n)=(x m0 1(n)+x m1 2(n))mod2 x1(n+7)=(x1(n+4)+x1(n))mod2 x²(n+7)=(x²(n+1)+x²(n))mod² however,

[0255]

number

[0256]

number

[0257] The cyclic shift values ​​m0, m1 are determined jointly or separately by the cell ID and / or SBTI. Knowing the relationship between the cell ID, SBTI, and m0, m1, as well as knowledge of the cell ID from PSS / SSS detection, hypotheses may be generated about the SBTI and used to detect which SBTI is indicated in the gold code.

[0258] It may be possible to generate two different gold sequences using two different cyclic shifts in the M-sequence. The first shift, which results in a reference DMRS, is used for pre-equalization, and the other shift, which results in a beacon DMRS, is used to indicate SBTI. If only one sequence is used, partial coherent / partial non-coherent detection can be performed. Different hypotheses are generated (using different frequency shifts of the individual M-sequences) to detect SBTI at the receiver.

[0259] The frequency or cyclic shift of the gold sequence can be: r=c((n+m0)modL) c(n)=(x1(n)+x2(n))mod2 x1(n+7)=(x1(n+4)+x1(n))mod2 x²(n+7)=(x²(n+1)+x²(n))mod²

[0260] The cyclic shift value m0 is determined by the cell ID and / or SBTI. Knowing the relationship between the cell ID, SBTI, and m0, as well as knowledge of the cell ID from PSS / SSS detection, a hypothesis can be generated about the SBTI and detect which SBTI is indicated by the gold code. This is a special case of "cyclic shift of individual M-sequences," where both sequences have the same shift (m0 = m1).

[0261] It may be possible to generate two different gold sequences using two different cyclic shifts in frequency: one used for pre-equalization and one used to indicate SBTI.

[0262] If only one sequence is used, partially coherent / partially non-coherent detection can be performed. To detect SBTI at the receiver, different hypotheses can be generated, for example, using different frequency shifts of this gold sequence.

[0263] Figure 34 is an example 3400 of DMRS and SBTI labels using circular shifting. Figure 35 is an example 3500 of DMRS and SBTI labels using circular shifting in a comb pattern. Circular shift techniques may be employed, and several examples are provided herein. The first sequence (reference DMRS) is generated using the following procedure. Initial value c init Using the

[0264]

number

[0265] The demodulation reference signal for the first OFDM symbol of the NR-PBCH can be generated as follows:

[0266]

number

[0267] is QPSK modulated,

[0268]

number

[0269]

number

[0270] is defined by

[0271] In the above formula,

[0272]

number

[0273] indicates the designated bandwidth in resource blocks for NR-PBCH transmission. The pseudo-random sequence c(i) may be defined in accordance with one or more embodiments described herein.

[0274] The second sequence (signal DMRS) is generated using the following procedure: A demodulation reference signal for the second OFDM symbol of the NR-PBCH is generated by a circular shift with respect to the sequence of the first symbol.

[0275]

number

[0276] In this example, k=2 or 3, depending on how many bits need to be indicated for the SS block timing index. These sequences can be mapped in a simple comb pattern. Due to the cyclic nature of the cyclic shift, the 8th tone of both the reference DMRS and the beacon DMRS is identical. This property can be used to estimate the CFO at the receiver, and the cyclic shift can be used to estimate the SBTI.

[0277] CFO estimates

[0278]

number

[0279] where fc is the carrier frequency and ΔnOFDM=2 (the distance between two OFDM symbols). This property is explained below.

[0280] For example, when m=0:17

[0281]

number

[0282] is shown in Table 1.

[0283] The eight rows (rows 0 to 8) shown in Table 1 represent different cyclic shifts used to indicate different SBTIs. Different rows are used to indicate the multiplier values ​​used for DMRS REs. These cyclic shifts are orthogonal to each other.

[0284] The circularly shifted DMRS may be applied in the time domain, where a phase shift in the frequency domain translates to a time index offset in the time domain, which can result in faster detection of SBTI (without multiple hypothesis testing).

[0285] Therefore, (DMRS pbch2 / DMRS pbch1 ) is a channel-free differential estimate (if the channel does not change significantly from symbol to symbol). The IFFTs of these ratios for each SBTI are time-shifted versions of each other. Therefore, coherent detection of SBTI can be performed quickly and with lower complexity.

[0286] A scrambling sequence, which may be a function of the SBTI, may be applied to the reference DMRS to generate a beacon DMRS. Using the scrambling pattern known to the receiver, hypotheses may be generated to find the SBTI, thereby allowing the SBTI to be detected.

[0287] The transmit power of the REs for the PBCH DMRS may be higher than that of the REs for the PBCH data. To achieve this, a power boost by a known factor may be applied to the PBCH DMRS transmission. Knowledge of this factor at the receiver may be important.

[0288] Although the features and elements of the present invention have been described in particular combinations in preferred embodiments, each feature or element may be used alone without the other features and elements of the preferred embodiments, or in various combinations with or without other features and elements of the present invention. It should be noted that while each of the beams shown in the figures is illustrated with respect to a particular direction, this is for illustrative purposes and no limitation with respect to a particular beam type, width, or direction is intended.

[0289] While the embodiments described herein consider LTE, LTE-A, New Radio (NR) or 5G-specific protocols, it will be understood that the embodiments described herein are not limited to this scenario and may also be applicable to other wireless systems.

[0290] Although features and elements are described above in particular combinations, those skilled in the art will understand that each feature or element may be used alone or in any combination with the other features and elements. Additionally, the embodiments described herein may be implemented in a computer program, software, or firmware embodied in a computer-readable medium for execution by a computer or processor. Examples of computer-readable media include electronic signals (transmitted via wired or wireless connections) and computer-readable storage media. Examples of computer-readable storage media include, but are not limited to, ROM, RAM, registers, cache memory, semiconductor memory devices, magnetic media such as internal hard disks and removable disks, magneto-optical media, and optical media such as CD-ROM disks and digital versatile disks (DVDs). Software and associated processors may be used to implement a radio frequency transceiver for use in a WTRU, UE, terminal, base station, RNC, or any host computer.

Claims

1. A method performed by a base station (BS), comprising: transmitting a synchronization signal block (SSB) consisting of four symbols; a first symbol in said four symbol period comprising a primary synchronization signal (PSS); a second symbol in the four-symbol period comprises a first physical broadcast channel (PBCH) signal and a first demodulation reference signal (first DMRS); a third symbol in said four symbol period comprises a secondary synchronization signal (SSS); a fourth symbol in the four symbol period comprising a second PBCH signal and a second DMRS; The first DMRS and the second DMRS are located on the same subcarrier. method.

2. 10. The method of claim 1, wherein the first DMRS is located on subcarriers according to a cell identifier (ID).

3. 2. The method of claim 1, wherein the PSS and the SSS occupy the same frequency spectrum, and the PBCH occupies a larger frequency spectrum than the PSS and the SSS.

4. The method of claim 1 , wherein the BS comprises an enhanced Node-b (eNB).

5. A base station (BS), a transmitter configured to transmit a synchronization signal block (SSB) consisting of four symbols; a first symbol in said four symbol period comprising a primary synchronization signal (PSS); a second symbol in the four-symbol period comprises a first physical broadcast channel (PBCH) signal and a first demodulation reference signal (first DMRS); a third symbol in said four symbol period comprises a secondary synchronization signal (SSS); a fourth symbol in the four symbol period comprising a second PBCH signal and a second DMRS; The first DMRS and the second DMRS are located on the same subcarrier. B.S.

6. The BS of claim 5 , wherein the first DMRS is located on a subcarrier according to a cell identifier (ID).

7. The BS of claim 5 , wherein the PSS and the SSS occupy the same frequency spectrum, and the PBCH occupies a larger frequency spectrum than the PSS and the SSS.

8. The BS of claim 5 , wherein the BS comprises an enhanced Node B (eNB).

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