Patent Application
20220418009
The disclosed embodiments relate generally to wireless communication, and, more particularly, to method for UE capability signaling to support enhancements of a random access operation for 5G New Radio (NR) in unlicensed spectrum (NR-U).
The wireless communications network has grown exponentially over the years. A Long-Term Evolution (LTE) system offers high peak data rates, low latency, improved system capacity, and low operating cost resulting from simplified network architecture. LTE systems, also known as the 4G system, also provide seamless integration to older wireless network, such as GSM, CDMA and Universal Mobile Telecommunication System (UMTS). In LTE systems, an Evolved Universal Terrestrial Radio Access Network (E-UTRAN) includes a plurality of evolved Node-Bs (eNodeBs or eNBs) communicating with a plurality of mobile stations, referred to as User Equipments (UEs). The 3rd Generation Partner Project (3GPP) network normally includes a hybrid of 2G/3G/4G systems. With the optimization of the network design, many improvements have developed over the evolution of various standards. The Next Generation Mobile Network (NGM board, has decided to focus the future NGMN activities on defining the end-to-end requirements for 5G New Radio (NR) systems.
In 3GPP release 16 specifications, support for 5G NR operating in unlicensed spectrum is introduced (such feature is also called NR-L) to bring to 5G a variety of options for flexibly utilizing the unlicensed spectrum. NR-U supports both license-assisted and standalone use of unlicensed spectrum. Specifically, standalone NR-U enables 5G to be deployed via small cell deployments and operated by any vertical end user without requiring licensed spectrum. This new feature will allow 5G NR to leverage the 5 GHz global band as well as the 6 Hz band, significantly increasing the spectrum reach of 5G.
With unlicensed operation, transmissions are regulated by regional regulations, such as Listen-Before Talk (LET), Occupied Channel Bandwidth (COB), and Power Spectrum Density (PSD), etc. In order to meet the LBT/OCB/PSD requirements, enhancements on the random access operation are proposed. However, these enhancements are not always required depending on which regions the User Equipment (UE are used. Moreover, these enhancements may require additional UE implementation efforts. Hence, it is desirable to have a flexible way for the UEs to support these enhancements for NR-U.
A method for UE capability signaling to support enhancements of a random access operation for NR-U is proposed. A HE transfers UE capability information to a mobile communication network, wherein the UE capability information comprises information indicating the UE's capability on random access operation in unlicensed spectrum. The UE receives configuration of an unlicensed cell from the mobile communication network. The UE performs a random access operation on the unlicensed cell according to the configuration.
In one embodiment, the UE capability information comprises a first indicator of whether the UE supports a Physical Random Access Channel (PRACH) transmission using a single long Zadoff-Chu (ZC) sequence, and the random access operation comprises performing the PRACH transmission using the single long ZC sequence. The ZC sequence has a length value of 1151 or 571, and the configuration comprises a PRACH sequence length being 1151 or 571. The unlicensed cell is configured by the mobile communication network as a Secondary Cell (SCell) for a carrier aggregation, or as a Primary SCell (PSCell) for a Dual Connectivity (DC) operation, or as a target cell for a handover.
In another embodiment, the UE capability information comprises a second indicator of whether the UE supports extension of a Random Access Response (RAR) window. The extension of the RAR window comprises extending the RAR window from 10 milliseconds to 40 milliseconds, and the configuration comprises an RAR window greater than 10 milliseconds. The random access operation comprises: monitoring an RAR from the mobile communication network for at most a duration of the RAR window; and decoding a 2-bit System Frame Number (SFN) indication in a Downlink Control Information (DCI) scheduling of the RAR.
In one example, the UE's capability on random access operation in unlicensed spectrum is set and reported per frequency band by the UE.
Other embodiments and advantages are described in the detailed description below. This summary does not purport to define the invention. The invention is defined by the claims.
The accompanying drawings, where like numerals indicate like components, illustrate embodiments of the invention.
Reference will now be made in detail to some embodiments of the invention, examples of which are illustrated in the accompanying drawings.
In addition to the gNB 121, the UE 110 is surrounded by one or more gNBs, including the gNB 101, which operate in an unlicensed band (e.g., 5 GHz or 6 GHz). The gNB 101 may be deployed by the same operator of the gNB 121, or may be deployed by a different operator than the operator of the gNB 121. The gNB 121 may form at least one cell which may be referred to as an NR-based licensed cell (i.e., a cell operating in a 5G NR licensed band). Similarly, the gNB 101 may form at least one cell which may be referred to as an NR-based unlicensed cell (i.e., a cell operating in an unlicensed band).
The UE 110 may be a smart phone, a wearable device, an Internet of Things (IoT) device, and a tablet, etc., and may or may not support random access operation (e.g., contention-based random access, and/or non-contention-based random access) on an unlicensed cell.
In accordance with one novel aspect, if the UE 110 supports random access operation on an unlicensed cell and camps on the cell (e.g., a PCell or PSCell) formed by the gNB 121, the UE 110 may transfer its UE capability information regarding the UE's capability on random access operation in unlicensed spectrum to the serving cell during a UE capability transfer procedure. After that, the gNB 121 may provide the UE 110 with configuration of the unlicensed cell, and the UE 110 may perform a random access operation on the unlicensed cell according to the configuration.
In one embodiment, the UE capability information comprises a first indicator of whether the UE supports a Physical Random Access Channel (PRACH) transmission using a single long Zadoff-Chu (ZC) sequence, and the random access operation comprises performing the PRACH transmission using the single long ZC sequence. For example, the first indicator may be a “prach-Wideband-r16” Information Element (IE) for indicating whether the UE supports enhanced PRACH design for operation with shared spectrum channel access by adopting a single long ZC sequence, with sequence=1151 for 15 KHz and ZC sequence=571 for 30 KHz.
In another embodiment, the UE capability information comprises a second indicator of whether the UE supports extension of a Random Access Response (RAR) window. For example, the second indicator may be a “extendedRAR-Window-r16” IE for indicating whether the UE supports RAR extension from 10 ms to 40 ms by decoding of the 2-bit System Frame Number (SFN) indication in Downlink Control Information (DCI) format 1_0.
Similarly, the UE 201 has a memory 202, a processor 203, and a radio frequency (RF) transceiver module 204. The RF transceiver 204 is coupled with the antenna 205, receives RF signals from the antenna 205, converts them to baseband signals, and sends them to the processor 203. The RF transceiver 204 also converts received baseband signals from the processor 203, converts them to RF signals, and sends out to the antenna 205. The processor 203 processes the received baseband signals and invokes different functional modules and circuits to perform features in the UE 201. The memory 202 stores data and program instructions 210 to be executed by the processor 203 to control the operations of the UE 201. Suitable processors include, by way of example, a special purpose processor, a digital signal processor (DSP), a plurality of micro-processors, one or more micro-processor associated with a DSP core, a controller, a microcontroller, application specific integrated circuits (ASICs), file programmable gate array (FPGA) circuits, and other type of integrated circuits (ICs), and/or state machines. A processor in associated with software may be used to implement and configure features of the UE 201.
The UE 201 also includes a protocol stack 260 and a set of control function modules and circuits 270. The protocol stack 260 may include a NAS layer to communicate with an AMF/SMF/MME entity connecting to the core network, an RRC layer for high layer configuration and control, a PDCP/RLC layer, a MAC layer, and a PHY layer. The Control function modules and circuits 270 may be implemented and configured by software, firmware, hardware, and/or combination thereof. The control function modules and circuits 270, when executed by the processor 203 via program instructions contained in the memory 202, interwork with each other to allow the UE 201 to perform embodiments and functional tasks and features in the network.
In one example, the control function modules and circuits 270 include a transmitter circuit 271 that transfers the information of the UE's capability on random access operation in unlicensed spectrum to the gNB 211, a receiver circuit 272 that receives configuration of an unlicensed cell from the gNB 211, and a random access handling circuit 273 that performs a random access operation on the unlicensed cell according to the received configuration.
If the random access operation is a non-contention-based random access, the random access operation ends at step S411 when the UE 401 receives and successfully decodes an RAR which is for the UE 401. Alternatively, if the random access operation is a contention-based random access, the UE 401 may proceed with uplink scheduled transmission (i.e., Msg-3) and contention resolution (i.e., Msg-4) after step S441.
In one embodiment, the UE capability information comprises a first indicator of whether the UE supports a PRACH transmission using a single long ZC sequence, and the random access operation comprises performing the PRACH transmission using the single long ZC sequence. The ZC sequence has a length value of 1151 or 571, and the configuration comprises a PRACH sequence length being 1151 or 571. The unlicensed cell is configured by the mobile communication network as a Secondary Cell (SCell) for a carrier aggregation, or as a Primary SCell (PSCell) for a Dual Connectivity (DC) operation, or as a target cell for a handover.
In another embodiment, the UE capability information comprises a second indicator of whether the UE supports extension of an RAR window. The UE capability information comprises a second indicator of whether the UE supports extension of an RAR window, and the configuration comprises an RAR window greater than 10 milliseconds. The random access operation comprises: monitoring an RAR from the mobile communication network for at most a duration of the RAR window; and decoding a 2-bit SFN indication in a DCI scheduling of the RAR.
In one example, the UE's capability on random access operation in unlicensed spectrum is set and reported per frequency band by the UE.
Although the present invention has been described in connection with certain specific embodiments for instructional purposes, the present invention is not limited thereto. Accordingly, various modifications, adaptations, and combinations of various features of the described embodiments can be practiced without departing from the scope of the invention as set forth in the claims.
This application is filed under 35 U.S.C. § 111(a) and is based on and hereby claims priority under 35 U.S.C. § 120 and § 365(c) from International Application No. PCT/CN2021/075456, with an international filing date of Feb. 5, 2021, which in turn claims priority from U.S. Provisional Application No. 62/970,791, filed on Feb. 6, 2020, and U.S. Provisional Application No. 63/014,813, filed on Apr. 24, 2020. This application is a continuation of International Application No. PCT/CN2021/075456, which claims priority from U.S. provisional applications 62/970,791 and 63/014,813. International Application No. PCT/CN2021/075456 is pending as of the filing date of this application, and the United States is a designated state in International Application No. PCT/CN2021/075456. The disclosure of each of the foregoing documents is incorporated herein by reference. the subject matter of which is incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62970791 | Feb 2020 | US | |
| 63014813 | Apr 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2021/075456 | Feb 2021 | US |
| Child | 17902826 | US |
