KR20200029671A - Apparatus and method of directional LBT configuration in NR-Unlicensed - Google Patents

Abstract

The present invention relates to a method for setting directional LBT for unlicensed band access in a next generation/5G wireless access network. According to an embodiment of the present invention, provided is a method for setting directional LBT for an unlicensed band in a next-generation/5G wireless network in which configuration information for direction LBT of a terminal is determined based on a synchronization signal block (SSB) reception beam.

Description

Apparatus and method of directional LBT configuration in NR-Unlicensed in a next generation wireless network in an unlicensed band

The present invention proposes a directional LBT setting method for unlicensed band access in a next generation / 5G wireless access network (hereinafter referred to as NR [New Radio] in the present invention). Specifically, a specific operation method and resource allocation method of directional reception beamforming based LBT will be described.

One embodiment provides a method for setting directional LBT for an unlicensed band in a next-generation wireless network, wherein configuration information for directional LBT of a terminal is determined based on an SSB reception beam.

1 is a view showing an example of symbol level alignment among different SCS.
2 is a diagram illustrating NR time domain structure depending on subcarrier-spacing.
3 is a view showing an NR PSS / SS / PBCH block.
4 is a conceptual diagram of SSB burst periodicity.
5 is a conceptual diagram of directional LBT.
6 is a conceptual diagram (Scheme 3-1) of scheduling according to a subband-based directional LBT.
7 is a conceptual diagram (Scheme 3-2) of scheduling according to a subband-based directional LBT.
8 is a diagram showing the configuration of a base station according to another embodiment.
9 is a view showing the configuration of a user terminal according to another embodiment.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. It should be noted that in adding reference numerals to the components of each drawing, the same components have the same reference numerals as possible even though they are displayed on different drawings. In addition, in describing the present invention, when it is determined that detailed descriptions of related well-known configurations or functions may obscure the subject matter of the present invention, detailed descriptions thereof will be omitted.

In the present specification, a wireless communication system means a system for providing various communication services such as voice and packet data. The wireless communication system includes a user equipment (UE) and a base station (BS).

The user terminal is a comprehensive concept that refers to a terminal in wireless communication, user equipment (UE) in WCDMA, LTE, HSPA and IMT-2020 (5G or New Radio), as well as MS (Mobile Station) in GSM, UT It should be interpreted as a concept including (User Terminal), SS (Subscriber Station), and wireless device.

Base station or cell (Cell) generally refers to a station (station) to communicate with the user terminal, Node-B (Node-B), eNB (evolved Node-B), gNB (gNode-B), LPN (Low Power Node) ), Sector, Site, Antennas of various types, Base Transceiver System (BTS), Access Point, Point (e.g., transmit point, receive point, transmit / receive point), relay node ( Relay Node), mega cell, macro cell, micro cell, pico cell, femto cell, remote radio head (RRH), radio unit (RU), and small cell (small cell).

Since the various cells listed above have a base station that controls each cell, the base station can be interpreted in two ways. 1) a device that provides a mega cell, a macro cell, a micro cell, a pico cell, a femto cell, or a small cell in relation to the wireless area, or 2) the wireless area itself. In 1), all devices that provide a predetermined wireless area are controlled by the same entity or interact to configure the wireless area in a collaborative manner. Points, transmission / reception points, transmission points, reception points, and the like, according to a configuration method of a wireless area, are examples of a base station. In 2), the radio area itself, which receives or transmits a signal from the viewpoint of the user terminal or the neighboring base station, may be directed to the base station.

In this specification, a cell is a component carrier having a coverage of a signal transmitted from a transmission / reception point or a signal transmitted from a transmission / reception point, or a transmission / reception point itself. You can.

In this specification, the user terminal and the base station are two (Uplink or Downlink) transmitting and receiving subjects used to implement the technology or technical idea described in the present invention, and are used in a comprehensive sense and are not limited by terms or words specifically referred to. Does not.

Here, the uplink (Uplink, UL, or uplink) means a method of transmitting and receiving data to the base station by the user terminal, the downlink (Downlink, DL, or downlink) transmits and receives data to the user terminal by the base station Means the way.

For uplink transmission and downlink transmission, a time division duplex (TDD) method transmitted using different times may be used, and a frequency division duplex (FDD) method, TDD method, and FDD method transmitted using different frequencies may be used. Mixing methods can be used.

In addition, in a wireless communication system, an uplink and a downlink are configured based on one carrier or a pair of carriers to configure a standard.

Uplink and downlink transmit control information through control channels such as PDCCH (Physical Downlink Control CHannel), PUCCH (Physical Uplink Control CHannel), and PDSCH (Physical Downlink Shared CHannel), PUSCH (Physical Uplink Shared CHannel), etc. It consists of the same data channel and transmits data.

Downlink (downlink) may mean a communication or communication path from a multiple transmit and receive point to a terminal, and uplink (uplink) may mean a communication or communication path from a terminal to a multiple transmit and receive point. At this time, in the downlink, the transmitter may be a part of multiple transmission / reception points, and the receiver may be a part of the terminal. In addition, in the uplink, the transmitter may be a part of the terminal, and the receiver may be a part of multiple transmission / reception points.

Hereinafter, a situation in which signals are transmitted / received through channels such as PUCCH, PUSCH, PDCCH and PDSCH is also described in the form of 'transmit and receive PUCCH, PUSCH, PDCCH and PDSCH'.

Meanwhile, the High Layer Signaling described below includes RRC signaling for transmitting RRC information including RRC parameters.

The base station performs downlink transmission to the terminals. The base station is a physical downlink for transmitting downlink control information such as scheduling required for reception of a downlink data channel, which is a main physical channel for unicast transmission, and scheduling grant information for transmission in an uplink data channel. The control channel can be transmitted. Hereinafter, the transmission and reception of signals through each channel will be described as a form in which the corresponding channel is transmitted and received.

There are no restrictions on the multiple access technique applied in a wireless communication system. Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Code Division Multiple Access (CDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Non-Orthogonal Multiple Access (NOMA), OFDM-TDMA, OFDM-FDMA, Various multiple access techniques such as OFDM-CDMA can be used. Here, NOMA includes SCMA (Sparse Code Multiple Access) and LDS (Low Density Spreading).

One embodiment of the present invention is to allocate resources such as asynchronous wireless communication evolving to LTE / LTE-Advanced, IMT-2020 via GSM, WCDMA, HSPA, and synchronous wireless communication evolving to CDMA, CDMA-2000 and UMB. Can be applied.

In this specification, a Machine Type Communication (MTC) terminal may mean a terminal supporting low cost (or low complexity) or a terminal supporting coverage enhancement. Or, in this specification, the MTC terminal may mean a terminal defined as a specific category for supporting low cost (or low complexity) and / or coverage enhancement.

In other words, in this specification, the MTC terminal may mean a newly defined 3GPP Release-13 low cost (or low complexity) UE category / type that performs LTE-based MTC-related operations. Alternatively, in this specification, the MTC terminal supports enhanced coverage compared to the existing LTE coverage, or UE category / type defined under the existing 3GPP Release-12 or lower supporting low power consumption, or the newly defined Release-13 low cost (or low complexity) UE category / type. Or, it may mean a further enhanced MTC terminal defined in Release-14.

In this specification, the NB-IoT (NarrowBand Internet of Things) terminal means a terminal supporting wireless access for cellular IoT. The objectives of the NB-IoT technology include improved indoor coverage, support for large-scale low-speed terminals, low sensitivity, ultra-low-cost terminal costs, low power consumption, and optimized network architecture.

As a representative usage scenario in NR (New Radio), which is currently being discussed in 3GPP, enhanced Mobile BroadBand (eMBB), Massive Machine Type Communication (mMTC), and Ultra Reliable and Low Latency Communication (URLLC) have been proposed.

In this specification, frequency, frame, subframe, resource, resource block, region, band, subband, control channel, data channel, synchronization signal, various reference signals, various signals, various messages related to NR (New Radio) Can be interpreted as meaning used in the past or present or various meanings used in the future.

Meanwhile, in the following description, a technical idea is described based on two nodes, a terminal and a base station, but this is only for convenience of understanding, and the same technical idea may be applied between the terminal and the terminal. For example, the base station described below is described by exemplarily describing one node that communicates with the terminal, and may be replaced with another terminal or infrastructure device that performs communication with the terminal, if necessary.

That is, the present technical idea may be applied not only to communication between a terminal and a base station, but also to communication between terminals (Device to Device), side link communication (Sidelink), and vehicle communication (V2X). In particular, it can also be applied to communication between terminals in a next-generation radio access technology, and terms such as a signal and a channel of the present specification can be variously modified and applied according to the type of communication between terminals.

For example, the terms PSS and SSS may be changed and applied to primary D2D Synchronization Signal (PSSS) and Secondary D2D Synchronization Signal (SSSS) in communication between terminals. In addition, the channel for transmitting broadcast information such as PBCH described above is changed to PSBCH, the channel for transmitting data in the sidelink such as PUSCH and PDSCH is changed to PSSCH, and the channel for transmitting control information such as PDCCH and PUCCH is changed to PSCCH. Can be applied. Meanwhile, a discovery signal is required in communication between terminals, which is transmitted and received through PSDCH. However, it is not limited to these terms.

Hereinafter, in this specification, the technical idea will be described based on exemplary communication between the terminal and the base station, but the base station node may be replaced with another terminal as necessary to apply the technical idea.

[5G NR (New Rat)]

3GPP supports multiple subcarrier-based frame structures in the NR frame structure.

Here, the basic SCS is 15 kHz, and a total of 5 SCS types are supported at 15 kHz X 2 μ. SCS values according to μ values are shown in Table 1 below.

As shown in Figure 1 below, it can be seen that the slot length varies depending on the numerology. That is, it can be seen that the shorter the slot length, the larger the SCS. Also, the slot defined in NR is defined based on 14 OFDM symbols.

- NR Time domain structure

NR supports the following structures on the time axis. Here, the difference from the existing LTE is that the basic scheduling unit has been changed to a slot in NR. Also, regardless of subcarrier-spacing, as shown in Figure 2, the slot is composed of 14 OFDM symbols. On the other hand, it supports a non-slot structure composed of 2,4,7 OFDM symbols, which are smaller scheduling units. The non-slot structure can be used as a scheduling unit for URLLC services.

■ Radio frame: Fixed 10ms regardless of numerology

■ Subframe: Fixed 1ms as a reference for time duration

   ◆ Do not use for data / control scheduling unit

■ Slot: Mainly for eMBB

   ◆ Include 14 OFDM symbols

■ Non-slot (i.e. mini-slot)

   ◆ Mainly for URLLC, but not limited to URLLC only

   ◆ Include 2, 4, or 7 OFDM symbols

■ One TTI duration

   ◆ A Time duration for data / control channel transmission

   ◆ A number of OFDM symbols per a slot / non-slot in the time main

 [ NR  SSB]

Unlike LTE, NR SSB (Synchronization Signal Block) can be transmitted in several subcarrier-spacing, and is always transmitted with PBCH. Also, a minimum required transmission band is defined for each subcarrier-spacing.

- Below 6GHz

 ■ "15kHz SCS and 5MHz" (except some specific band (e.g. band n41, n77 and n78 have 30SCS and 10MHz)

- Above 6GHz

 ■ "120kHz SCS and 10MHz"

Also, subcarrier-spacing supported by frequency bands is different.

- SCS supported for bands below 1 GHz

 ■ 15kHz, 30kHz and 60kHz

- SCS supported for bands between 1GHz and 6GHz

 ■ 15kHz, 30kHz, 60kHz

- SCS supported for bands above 24GHz and below 52.6GHz

 ■ 60 kHz, 120 kHz

 ■ 240 kHz is not applicable for data

The SSB is transmitted by defining an SSB burst set rather than a single type. Basically, the SSB burst set is 5ms regardless of numerology, and the maximum number L of SSB blocks that can be transmitted in the set is as follows.

- For frequency range up to 3 GHz, L is 4

- For frequency range from 3 GHz to 6 GHz, L is 8

- For frequency range from 6 GHz to 52.6 GHz, L is 64

In addition, the period in which the SSB burst set defined in this way is transmitted is additionally set to RRC to be indicated to the UE.

The terminal performing the initial access assumes a default = 20ms period and performs system information update after obtaining synchronization. Thereafter, the SSB burst periodicity value is finally updated by the gNB.

Currently, NR-U is considering stand-alone design for unlicensed bands. In addition, NR-U considers a high frequency band of 7 GHz or higher. At this time, since beam-based operation is basically applied, it is necessary to introduce directional LBT in consideration of the environment.

The present invention proposes a directional LBT setting method for unlicensed band access in a next generation / 5G wireless access network (hereinafter referred to as NR [New Radio] in the present invention). Specifically, a specific operation method and resource allocation method of directional reception beamforming based LBT will be described.

Currently, NR is conducting an Rel-16 Study Item called 'NR-based Access to Unlicensed Spectrum' for unlicensed band access. The LBT-related agreement for NR-U is as follows. (RAN1 # 94 Chairman's notes)

Agreement:

● It is recommended to define a mechanism to transmit SSBs dropped due to LBT failure

● Following are examples of candidate mechanisms for further consideration with enhancements or modifications not precluded:

o Alt-1: Shift SSB (s) in time to the next transmission instance

o Alt-2: Cyclically wrap the SSBs dropped due to LBT failure around to the end of the burst set transmission

o Alt-3: Network to flexibly position SSB index and indicate the timing information

o Other alternatives are not precluded

● It is recommended to define a mechanism for UE (s) to determine the timing and QCL assumptions from the detected SSB

Agreement:

If preamble transmissions are dropped due to LBT failure, then

o From a RAN1 perspective, it is recommended that preamble power ramping is not performed and that the preamble transmission counter is not incremented

Agreement:

o In some scenarios it is beneficial for the maximum RAR window size to be extended beyond 10 ms to increase robustness to DL LBT failure

o FFS: Value of maximum RAR window size

In the present invention, the operation method is described on the premise of the introduction of directional LBT. As shown in FIG. 5, beam-based operation is basically performed in a high center frequency band, and all corresponding data / control channels are transmitted in the form of beamforming. Therefore, the LBT must also be operated using beamforming characteristics,

5, simultaneous transmission is possible without interfering with each other by beams aligned in a specific direction. That is, in Omni beam-based transmission, UE # 1 and # 2 cannot simultaneously transmit data, but when directional beam-based LBT is applied, the probability of LBT success increases between UEs to which beams that do not cause interference are applied in some cases. As a result, frequency efficiency can be increased.

Solution 1. Set performance setting information for a directional LBT to a terminal.

In performing directional LBT to the UE, the gNB must transmit configuration information for the LBT direction. First, when the UE performs directional LBT, reference TRSs of various TCIs can be set based on which reference beam is used. That is, the terminal may set an information field capable of selecting a specific RS for a configuration information element of directional LBT through higher layer configuration information.

Option 1-1. The performance information on the directional LBT of the UE is performed based on the SSB reception beam.

It is assumed that the reference information for the directional LBT setting of the terminal is set based on the SSB reception beam. That is, the terminal has RX beam information set to receive the first SSB. At this time, the gNB may be configured to perform reception beam-based LBT on the N SSBs of the terminal. That is, the terminal performs LBT using the RX beam receiving the corresponding SSB according to the SSB index information referred to as gNB. In this case, the directional LBT may be performed in one specific direction, or may be set to be performed in all the N directions.

Option 1-2. The performance information for performing the directional LBT of the UE is performed based on the received beam through multiple CSI-RS configuration.

The gNB configures multiple CSI-RS resources to the terminal. In this case, a method of performing directional LBT can be performed by referring to CSI-RS resource indexes. Basically, directional LBT is performed based on CSI-RS resource sets set for the UE. For example, it can be applied as shown in Table 2 below. When performing beam estimation based on each CSI-RS resource, the UE selects Rx_beam capable of receiving the CSI-RS in an optimal quality at this time. However, this information is not transmitted to the gNB. Next, when performing this operation for all currently set CSI-RS resources, it can be seen that Rx_beams suitable for Tx_beams set for each CSI-RS resource are paired. At this time, in the LBT configuration information set by the gNB, such CSI-RS-based reception beamforming may be set as directional LBT candidates for uplink data transmission of an actual terminal. As shown in Table 2 below, the gNB may be set to perform directional LBT by selecting all or a portion of all beams.

Scheme 1-3. The UE's directional LBT performance information is performed based on a multiple RACH transmission beam.

In this proposal, unlike the aforementioned methods 1 and 2, the contents of performing the LBT of the terminal based on the uplink channel are described. That is, the UE can perform multiple resource configuration for the uplink RACH through the existing beam management process, and at this time, it is possible to pair the appropriate Tx_beam for each RACH resource. Therefore, when the UE performs directional LBT before transmission of the uplink data or control channel, LBT is performed in the corresponding direction based on the configuration information of the RACH. That is, it means that the terminal uses the set Tx beam information for transmitting the RACH to the Rx-based directional LBT process. The content can be set to be applied to directional LBT by selecting all or part of the multiple RACH resources set as in the above method 1-2.

Option 1-4. The UE's directional LBT performance information is performed based on a multiple SRS / PUCCH transmission beam.

In this proposal, the principle of setting the LBT set based on the uplink channel or the signal is the same as the previously proposed methods 1-3. However, it means that the UE performs directional LBT based on Tx beam information of the UE configured using multiple SRS or PUCCHs. The following operation is the same.

Option 2. Interpretation of the reception result can be selectively performed in the directional LBT.

In performing the directional LBT, the gNB or the UE can derive two procedures as follows. The interpretation of the LBT result is applied from the gNB / UE point of view, and may be determined in advance or given in the form of mode setting information through higher layer signaling.

-Alt.1: If power / energy above the standard is detected even in one of the directional LBT results, it moves or backoffs to the next time.

Here, if energy detection / power detection exceeds a threshold value in one specific direction through LBT, it is determined that the LBT itself has failed. That is, it matches the existing operation, but the LBT for a specific cycle is maintained. That is, directional LBT for N directions is applied, and N unit directional LBT basic units of the CCA section may be configured, or N LBT basic unit sections may be set with N subbands.

-Alt.2: If power / energy below the standard is detected even in one of the directional LBT results, data transmission is performed in that direction

Here, if energy detection / power detection does not exceed a threshold value in a specific direction through LBT, it is determined that LBT itself is successful. That is, it is different from the existing operation. For the direction in which no energy was detected through the directional LBTs, the gNB / UE assumes that the LBT is successful for the direction. Therefore, only in the direction in which the directional LBT is successful, the gNB / UE can transmit signals / data.

In this method, the gNB can apply a directional LBT process in a subband (20 MHz basic unit) unit. At this time, in order to set the subband based directional LBT, the gNB needs to transmit LBT direction setting information for each subband to perform directional LBT to the UE. First, when a UE performs directional LBT, reference RSs of various TCIs can be set based on which reference beam is used. That is, the terminal may set an information field capable of selecting a specific RS for a configuration information element of directional LBT through higher layer configuration information. The specific method of using and setting up / down signals / channels follows 'Method 1,1-1,1-2,1-3,1-4'.

Method 3. Success-oriented scheduling can be selectively applied to directional LBT.

In this proposal, a specific scheduling method according to directional LBT success is discussed. As mentioned above, the directional LBT determines whether a channel is busy through energy detection in a specific direction. That is, it may be assumed that the channel is empty in a direction in which energy below a reference value is detected through energy detection. Therefore, this proposal proposes a specific scheduling method according to the interpretation method of the directional LBT.

Option 3-1. For the beam direction in which the directional LBT is successful, the entire transmission band can be scheduled.

The gNB / terminal performs LBTs for a specific direction. There are two ways to perform LBT.

- Alt.1: time domain LBT

- Alt.2: Subband-based LBT (= Frequency domain LBT)

Here, according to the present proposal, it means scheduling using all resources in the allotted band or BWP. For example, as a result of performing LBT for each subband as shown in FIG. 6, it is assumed that directional LBT is successful in Subband # 1 using Rx_beam # 1. According to this proposal, in this case, scheduling can be performed for all subbands in the BWP. Even if LBT fails in Subband # 0 and Subband # 2, the gNB can allocate DL resources for all bands, and the UE can also transmit uplink signals / channels such as PUSCH / PUCCH using all subbands. However, there is one limitation. For example, if LBT is successful through Rx_beam # 1 as shown in Figure 6, the signal / channel must be transmitted with the Tx beam corresponding to the beam. That is, Tx-RX beam reciprocity characteristics should be applied. That is, since the channel is empty only in the corresponding direction from the gNB / UE position of the transmitting end, the transmission is also performed only in the direction in which the channel is empty.

If the directional LBTs succeed in multiple 'subbands' or 'time periods', the transmission beam can be set by the following combination.

- Alt.1: Randomly select one of Rx_beams that succeeded in LBT (Random method) and set the transmission beam based on the beam.

- Alt.2: Among the Rx_beams that succeeded in LBT, one with the lowest energy detection value is selected, and a transmission beam is set based on the corresponding beam.

- Alt.3: Rx_beams that succeed in LBT First, the beam that successfully succeeds in LBT is selected, and a transmission beam is set based on the beam.

- Alt.4: Set the transmission beam in the form of a composite beam for Rx_beams that succeeded in LBT.

Option 3-2. Scheduling can be performed only for a band in which the directional LBT is successful.

This method is the same as the above-described method 3-1, but the setting for the band participating in the scheduling may be different.

Basically, the process of selecting a transmission beam based on Rx_beam that succeeded in LBT is the same. However, in the case of performing subband-based directional LBT, there is an additional limitation of scheduling using only the subband in which the directional LBT is successful. For example, as shown in FIG. 7, uplink / downlink resource allocation and scheduling are possible using a transmission beam set based on Rx_beam # 1 only in Subband # 1 that has succeeded in directional LBT.

The present invention proposes a directional LBT setting method for unlicensed band access in a next generation / 5G wireless access network (hereinafter referred to as NR [New Radio] in the present invention). Specifically, a specific operation method and resource allocation method of directional reception beamforming based LBT will be described.

8 is a diagram showing the configuration of a base station 1000 according to another embodiment.

Referring to FIG. 8, the base station 1000 according to another embodiment includes a control unit 1010, a transmission unit 1020, and a reception unit 1030.

In the method of setting the directional LBT for the unlicensed band in the next generation wireless network required to perform the present invention, the control unit 1010 is characterized in that the configuration information for the directional LBT of the terminal is determined based on the SSB reception beam Controls the overall operation of the base station 1000 according to the method.

The transmitting unit 1020 and the receiving unit 1030 are used to transmit and receive signals, messages, and data necessary to perform the present invention described above.

9 is a diagram showing the configuration of a user terminal 1100 according to another embodiment.

Referring to FIG. 9, the user terminal 1100 according to another embodiment includes a reception unit 1110, a control unit 1120, and a transmission unit 1130.

The reception unit 1110 receives downlink control information, data, and messages from a base station through a corresponding channel.

In addition, the control unit 1120 in the method of setting the directional LBT for the unlicensed band in the next-generation wireless network required to perform the present invention, the configuration information for the directional LBT of the terminal is determined based on the SSB reception beam The overall operation of the user terminal 1100 according to the method is controlled.

The transmitter 1130 transmits uplink control information, data, and a message to the base station through a corresponding channel.

In addition, the terms "system", "processor", "controller", "component", "module", "interface", "model", "unit", etc. are generally related to computer-related entity hardware, a combination of hardware and software, It can mean software or running software. For example, the components described above may be, but are not limited to, processes, processors, controllers, control processors, entities, threads of execution, programs and / or computers driven by a processor. For example, both an application running on a controller or processor and a controller or processor can be a component. One or more components can be in a process and / or thread of execution, and the components can be located on one system or deployed to more than one system.

The standard contents or standard documents mentioned in the above-described embodiments are omitted to simplify the description of the specification and constitute a part of the specification. Therefore, it should be construed that adding the contents of the above standard contents and a part of the standard documents to the present specification or in the claims falls within the scope of the present invention.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and variations without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain them, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the claims below, and all technical spirits within the scope equivalent thereto should be interpreted as being included in the scope of the present invention.

Claims (1)

In the method of setting the directional LBT for the unlicensed band in the next generation wireless network,
Method for setting the information on the directional LBT of the terminal is determined based on the SSB reception beam.

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