1111111111111111 IIIIII IIIII 111111111111111 11111 111111111111111 IIIII IIIII 1111111111 11111111
`US 20190053294Al
`
`c19) United States
`c12) Patent Application Publication
`Xia et al.
`
`c10) Pub. No.: US 2019/0053294 Al
`Feb. 14, 2019
`(43) Pub. Date:
`
`(54) BEAM FAILURE RECOVERY REQUEST
`
`Publication Classification
`
`(71)
`
`Applicant: Futurewei Technologies, Inc., Plano,
`TX (US)
`
`(72)
`
`Inventors: Pengfei Xia, San Diego, CA (US);
`Young Hoon Kwon, San Diego, CA
`(US); Bin Liu, San Diego, CA (US)
`
`(73)
`
`Assignee: Futurewei Technologies, Inc., Plano,
`TX (US)
`
`(21) Appl. No.: 15/814,372
`
`(22) Filed:
`
`Nov. 15, 2017
`
`Related U.S. Application Data
`
`(60) Provisional application No. 62/543,765, filed on Aug.
`10, 2017.
`
`(2006.01)
`(2006.01)
`(2006.01)
`(2006.01)
`
`(51)
`
`(52)
`
`Int. Cl.
`H04W 76102
`H04W 76104
`H04W72/12
`H04W 74108
`U.S. Cl.
`CPC ....... H04W 761028 (2013.01); H04W 761046
`(2013.01); H04W 72/0433 (2013.01); H04W
`7410833 (2013.01); H04W 7211289 (2013.01)
`ABSTRACT
`(57)
`The disclosure relates to technology for beam failure recov(cid:173)
`ery in user equipment, comprising detecting a beam failure
`event between the user equipment and a base station, send(cid:173)
`ing a first beam failure recovery request (BFRQ) to the base
`station upon detection of the beam failure and searching for
`a beam failure recovery response (BFRP) within a first
`response window.
`
`100
`
`110A
`
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`150
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`
`gNB 170B
`
`\ __________ _
`
`Samsung Exhibit 1004, Page 1 of 22
`
`

`

`Patent Application Publication
`
`Feb. 14, 2019 Sheet 1 of 10
`
`US 2019/0053294 Al
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`Samsung Exhibit 1004, Page 2 of 22
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`

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`Patent Application Publication
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`Feb. 14, 2019 Sheet 2 of 10
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`Samsung Exhibit 1004, Page 3 of 22
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`

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`
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`
`Samsung Exhibit 1004, Page 4 of 22
`
`

`

`Patent Application Publication
`
`Feb. 14, 2019 Sheet 4 of 10
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`Samsung Exhibit 1004, Page 5 of 22
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`

`

`Patent Application Publication
`
`Feb. 14, 2019 Sheet 5 of 10
`
`US 2019/0053294 Al
`
`Use PUCCH
`504
`
`Use BRACH
`506
`
`FIG. 5A
`
`PUCCH-BFRQ (PBO)
`
`BRACH-BFRQ (BBO)
`
`time
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`Before t2
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`Response (BFRP) expected
`After t2
`
`FIG. 5B
`
`BRACH-BFRQ
`
`PUCCH-BFRQ
`
`t2
`
`t1
`
`time
`
`FIG. 5C
`
`Samsung Exhibit 1004, Page 6 of 22
`
`

`

`Patent Application Publication
`
`Feb. 14, 2019 Sheet 6 of 10
`
`US 2019/0053294 Al
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`Samsung Exhibit 1004, Page 7 of 22
`
`

`

`Patent Application Publication
`
`Feb. 14, 2019 Sheet 7 of 10
`
`US 2019/0053294 Al
`
`PUCCH-BFRQ
`(PBO)
`
`BRACH-BFRQ#1
`(BBO)
`
`I
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`
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`BRACH-BFRQ
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`
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`
`FIG. 68
`
`Samsung Exhibit 1004, Page 8 of 22
`
`

`

`Patent Application Publication
`
`Feb. 14, 2019 Sheet 8 of 10
`
`US 2019/0053294 Al
`
`702
`
`704
`
`706
`
`Detect beam failure
`event
`
`Send a first BFRQ
`
`Search for BFRP
`within first response
`window
`
`FIG. 1A
`
`708
`
`7'10
`
`Send a second BFRO
`for same beam failure
`event
`
`Indicate first and
`second BRFQ
`correspond to same
`beam failure event
`
`/
`
`/
`
`/
`
`/
`
`Marking the second
`BFRQ
`
`Placing a pointer to
`the first BRFQ
`
`'
`
`,
`
`,
`
`Placing a beam failure
`event ID in the first
`and second BFRQs
`
`/
`
`/
`
`/
`
`/
`
`' ' '
`
`'
`
`710A
`
`710B
`
`710C
`
`FIG. 7B
`
`Samsung Exhibit 1004, Page 9 of 22
`
`

`

`Patent Application Publication
`
`Feb. 14, 2019 Sheet 9 of 10
`
`US 2019/0053294 Al
`
`User Equipment 800
`
`110
`808
`
`Base Station 850
`
`Processor
`858
`
`J 8 1 0
`
`Transceiver
`802
`
`Processor
`804
`
`Memory
`806
`
`FIG. BA
`
`J 8 6 0
`
`Transmitter -
`
`852
`
`Receiver -
`
`854
`
`Memory
`856
`
`FIG. BB
`
`Samsung Exhibit 1004, Page 10 of 22
`
`

`

`Patent Application Publication
`
`Feb. 14, 2019 Sheet 10 of 10 US 2019/0053294 Al
`
`900
`
`901
`
`970
`
`CPU
`910
`
`Mass Storage
`930
`
`Network
`Interface
`950
`
`Memory
`920
`
`Detecting Module
`821A
`
`Sending Module
`9218
`
`Indicating Moduie
`921C
`
`Transmitting
`Module
`921D
`~
`
`Receiving Module
`921E
`
`1/0
`Interface
`960
`
`Samsung Exhibit 1004, Page 11 of 22
`
`

`

`US 2019/0053294 Al
`
`Feb. 14,2019
`
`1
`
`BEAM FAILURE RECOVERY REQUEST
`
`CLAIM FOR PRIORITY
`
`[0001] This application claims the benefit of priority to
`U.S. Provisional Application No. 62/543, 765, filed Aug. 10,
`2017, the entire contents of which are hereby incorporated
`by reference.
`
`FIELD
`
`[0002] The disclosure generally relates to wireless com(cid:173)
`munication networks, and in particular, to recovering from
`a beam failure between user equipment and a base station.
`
`BACKGROUND
`
`[0003] As the demand for capacity in mobile broadband
`communications increases drastically every year, wireless
`communication systems are increasing their capability of
`handling mobile traffic. In next generation systems, such as
`fifth generation (5G) technologies, advanced communica(cid:173)
`tions, such as millimeter-wave (mm-wave) communications,
`with potential multigigabit-per-second data rates are candi(cid:173)
`date technologies to increase overall capacity and transmis(cid:173)
`sion speeds. Highly directional beamforming antennas are
`necessary at both the base station (BS) and mobile station
`(MS) to compensate for the high attenuation in the mm(cid:173)
`wave frequency band and to extend its transmission range.
`[0004] A misalignment between transmitting (TX) and
`receiving (RX) beams may cause a significant loss in the
`received power, especially for systems with narrow beams,
`and result in beam failure. To avoid such beam failure, beam
`aligmnent in mm-wave communication systems is necessary
`to find the best beam pair from all possible beam pairs for
`maximum beamforming efficiency. However, when a beam
`failure occurs, a reporting and recovery mechanism is
`employed to report and recover from the failure. During the
`3GPP TSG RAN WGl #89, it was agreed upon to support
`a non-contention based channel based on the Physical Ran(cid:173)
`dom Access Channel (PRACH) and the Physical Uplink
`Control Channel (PUCCH) for beam failure recovery
`request transmission. PRACH denotes a Long Term Evolu(cid:173)
`tion (LTE) uplink channel transmitted by a terminal so as to
`establish initial synchronization, whereas PUCCH denotes
`an LTE uplink control channel, and includes Channel Qual(cid:173)
`ity Indicator (CQI) information.
`
`BRIEF SUMMARY
`
`[0005] According to one aspect of the present disclosure,
`there is a method for beam failure recovery in user equip(cid:173)
`ment, including detecting a beam failure event between the
`user equipment and a base station; sending a first beam
`failure recovery request (BFRQ) to the base station upon
`detection of the beam failure event; and searching for a beam
`failure recovery response (BFRP) within a first response
`window.
`[0006] Optionally, in any of the preceding aspects, sending
`the BFRQ is carried out in the physical layer of the user
`equipment.
`[0007] Optionally, in any of the preceding aspects, the first
`BFRQ is sent using one of a physical uplink channel
`(PUCCH) or a random access channel for beam failure
`recovery (PRACH).
`[0008] Optionally, in any of the preceding aspects, the first
`response time window is a PUCCH response window when
`
`the BFRQ is sent using the PUCCH, or the first response
`time window is a beam failure random access channel
`response window when the BFRQ is sent using the random
`access channel for beam failure recovery (PRACH).
`[0009] Optionally, in any of the preceding aspects, a
`parameter of the first response time window is at least one
`of a response window starting position in time, a response
`window ending position in time or a response window
`duration in time.
`[0010] Optionally, in any of the preceding aspects, a
`configuration of the response time window is signaled to the
`user equipment in at least one of a radio resource control
`(RRC) message or a downlink control information (DCI)
`message.
`[0011] Optionally, in any of the preceding aspects, the first
`BFRQ is sent using the PUCCH when a PUCCH-BFRQ
`opportunity arrives before a PRACH-BFRQ opportunity.
`[0012] Optionally, in any of the preceding aspects, the first
`BFRQ is sent using the PUCCH when a PUCCH-BFRQ
`opportunity arrives after a PRACH-BFRQ opportunity.
`[0013] Optionally, in any of the preceding aspects, the
`PUCCH-BFRQ arrives at a first time and the PRACH(cid:173)
`BFRQ arrives at a second time, and the PUCCH-BFRQ is
`sent at the first time when a PUCCH-BFRQ opportunity
`response is expected before a PRACH-BFRQ opportunity at
`the second time, unless a sum of the first time and a response
`time exceeds the second time.
`[0014] Optionally, in any of the preceding aspects, the
`method further includes sending a second BFRQ to the base
`station for a same beam failure event; and indicating to the
`base station that the first and second BFRQs correspond to
`the same beam failure event.
`[0015] Optionally, in any of the preceding aspects, the
`indicating includes one of marking the second BFRQ as
`secondary in time or order, placing a pointer to the first
`BFRQ in the second BFRQ indicating that the first and
`second BFRQs correspond to the same beam failure event,
`and placing a beam failure event ID in the first BFRQ and
`the second BFRQ with the same beam failure event ID.
`[0016] Optionally, in any of the preceding aspects, the
`method further includes receiving first and second beam
`failure recovery responses (BFRPs) from the base station,
`wherein the BFRP includes one of a mark in the second
`BFRP as secondary as secondary in time or order, a pointer
`in the second BFRP to the first BFRP indicating that the first
`and second BFRPs correspond to the same beam failure
`event, and a beam failure event ID in the first and second
`BFRPs with the same beam failure event ID.
`[0017] Optionally, in any of the preceding aspects, the
`second BFRQ is on a different channel or carrier frequency
`than the first BFRQ.
`[0018] According to another embodiment of the present
`disclosure, there is a device for beam failure recovery in user
`equipment, including a non-transitory memory storage com(cid:173)
`prising instructions; and one or more processors in commu(cid:173)
`nication with the memory, wherein the one or more proces(cid:173)
`sors execute the instructions to detect a beam failure event
`between the user equipment and a base station; send a first
`beam failure recovery request (BFRQ) to the base station
`upon detection of the beam failure event; and search for a
`beam failure recovery response (BFRP) within a first
`response window.
`[0019] According to still another aspect of the present
`disclosure, there is a non-transitory computer-readable
`
`Samsung Exhibit 1004, Page 12 of 22
`
`

`

`US 2019/0053294 Al
`
`Feb. 14,2019
`
`2
`
`medium storing computer instructions for beam failure
`recovery in user equipment, that when executed by one or
`more processors, cause the one or more processors to
`perform the operations of detecting a beam failure event
`between the user equipment and a base station; sending a
`first beam failure recovery request (BFRQ) to the base
`station upon detection of the beam failure event; and search(cid:173)
`ing for a beam failure recovery response (BFRP) within a
`first response window.
`[0020] This Summary is provided to introduce a selection
`of concepts in a simplified form that are further described
`below in the Detailed Description. This Summary is not
`intended to identify key features or essential features of the
`claimed subject matter, nor is it intended to be used as an aid
`in determining the scope of the claimed subject matter. The
`claimed subject matter is not limited to implementations that
`solve any or all disadvantages noted in the Background.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0021] Aspects of the present disclosure are illustrated by
`way of example and are not limited by the accompanying
`figures for which like references indicate elements.
`[0022] FIG. 1 illustrates a wireless network for commu(cid:173)
`nicating data.
`[0023] FIG. 2 illustrates a base station with transmitting
`and receiving beams according to an example embodiment
`[0024] FIG. 3 illustrates physical channels and transmit(cid:173)
`ting signals on the physical channels in accordance with
`FIG. 2.
`[0025] FIGS. 4A and 4B illustrate examples of beam
`failure between a base station and user equipment.
`[0026] FIG. 4C illustrates a multiple input multiple output
`(MIMO) system with m transmit and n receive antennas.
`[0027] FIGS. SA-SC illustrate a flow diagram for selection
`of a channel and examples of time of arrival for multiple
`beam failure recovery requests.
`[0028] FIG. SD is an example diagram illustrating sched(cid:173)
`uling request opportunities for user equipment to be config(cid:173)
`ured.
`[0029] FIGS. 6A and 6B illustrate timing diagrams for
`sending multiple beam failure requests and responses.
`[0030] FIGS. 7 A and 7B illustrate flow diagrams in accor(cid:173)
`dance with the disclosed embodiments.
`[0031] FIG. SA illustrates example user equipment that
`may implement the methods and teachings according to this
`disclosure.
`[0032] FIG. SB illustrates example base station that may
`implement the methods and teachings according to this
`disclosure.
`[0033] FIG. 9 is a block diagram of a network device that
`can be used to implement various embodiments.
`
`DETAILED DESCRIPTION
`
`[0034] The disclosure relates to technology for recovering
`from a beam failure between user equipment and a base
`station.
`[0035] User equipment and base stations establish a con(cid:173)
`nections using downlink and uplink beam pairs. Often times,
`for example as a result of blockage or user equipment
`rotation or displacement, the connection between the user
`equipment and the base station is disrupted, resulting in a
`beam failure. To overcome such failure, a beam failure
`recovery mechanism may help to improve high frequency
`
`link performance. In particular, a beam failure recovery
`request (BFRQ) and response (BFRQ) method based on a
`PRACH-like channel and PUCCH is disclosed. The dis(cid:173)
`closed mechanism determines whether the BFRQ should be
`sent using the PRACH-like channel or the PUCCH, depend(cid:173)
`ing on the expected BFRQ.
`[0036]
`It is understood that the present embodiments of
`the disclosure may be implemented in many different forms
`and that claims scopes should not be construed as being
`limited to the embodiments set forth herein. Rather, these
`embodiments are provided so that this disclosure will be
`thorough and complete and will fully convey the inventive
`embodiment concepts to those skilled in the art. Indeed, the
`disclosure is intended to cover alternatives, modifications
`and equivalents of these embodiments, which are included
`within the scope and spirit of the disclosure as defined by the
`appended claims. Furthermore, in the following detailed
`description of the present embodiments of the disclosure,
`numerous specific details are set forth in order to provide a
`thorough understanding. However, it will be clear to those of
`ordinary skill in the art that the present embodiments of the
`disclosure may be practiced without such specific details.
`[0037] FIG. 1 illustrates a wireless network for commu(cid:173)
`nicating data. The communication system 100 includes, for
`example, user equipment ll0A-ll0C, radio access networks
`(RANs) 120A-120B, a core network 130, a public switched
`telephone network (PSTN) 140, the Internet 150, and other
`networks 160. Additional or alternative networks include
`private and public data-packet networks including corporate
`intranets. While certain numbers of these components or
`elements are shown in the figure, any number of these
`components or elements may be included in the system 100.
`[0038]
`In one embodiment, the wireless network may be a
`fifth generation (5G) network including at least one 5G base
`station which employs orthogonal frequency-division mul(cid:173)
`tiplexing (OFDM) and/or non-OFDM and a transmission
`time interval (TTI) shorter than 1 ms (e.g. 100 or 200
`microseconds), to communicate with the communication
`devices. In general, a base station may also be used to refer
`any of the eNB and the 5G BS (gNB). In addition, the
`network may further include a network server for processing
`information received from the communication devices via
`the at least one eNB or gNB.
`[0039] System 100 enables multiple wireless users to
`transmit and receive data and other content. The system 100
`may implement one or more channel access methods, such
`as but not limited to code division multiple access (CDMA),
`time division multiple access (TDMA), frequency division
`multiple access (FDMA), orthogonal FDMA (OFDMA), or
`single-carrier FDMA (SC-FDMA).
`[0040] The user equipment (UE) ll0A-ll0C are config(cid:173)
`ured to operate and/or communicate in the system 100. For
`example, the user equipment ll0A-ll0C are configured to
`transmit and/or receive wireless signals or wired signals.
`Each user equipment ll0A-ll0C represents any suitable end
`user device and may include such devices ( or may be
`referred to) as a user equipment/device, wireless transmit/
`receive unit (WTRU), mobile station, fixed or mobile sub(cid:173)
`scriber unit, pager, cellular telephone, personal digital assis(cid:173)
`tant (PDA), smartphone,
`laptop, computer,
`touchpad,
`wireless sensor, or consumer electronics device.
`[0041]
`In the depicted embodiment, the RANs 120A-120B
`include one or more base stations 170A, 170B ( collectively,
`base stations 170), respectively. Each of the base stations
`
`Samsung Exhibit 1004, Page 13 of 22
`
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`

`US 2019/0053294 Al
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`Feb. 14,2019
`
`3
`
`170 is configured to wirelessly interface with one or more of
`the UEs 110A, 110B, ll0C to enable access to the core
`network 130, the PSTN 140, the Internet 150, and/or the
`other networks 160. For example, the base stations (BSs)
`170 may include one or more of several well-known devices,
`such as a base transceiver station (BTS), a Node-B (NodeB),
`an evolved NodeB (eNB), a next (fifth) generation (5G)
`NodeB (gNB), a Home NodeB, a Home eNodeB, a site
`controller, an access point (AP), or a wireless router, or a
`server, router, switch, or other processing entity with a wired
`or wireless network.
`[0042]
`In one embodiment, the base station 170A forms
`part of the RAN 120A, which may include other base
`stations, elements, and/or devices. Similarly, the base station
`170B forms part of the RAN 120B, which may include other
`base stations, elements, and/or devices. Each of the base
`stations 170 operates to transmit and/or receive wireless
`signals within a particular geographic region or area, some(cid:173)
`times referred to as a "cell." In some embodiments, mul(cid:173)
`tiple-input multiple-output (MIMO) technology may be
`employed having multiple transceivers for each cell.
`[0043] The base stations 170 communicate with one or
`more of the user equipment ll0A-ll0C over one or more air
`interfaces (not shown) using wireless communication links.
`The air interfaces may utilize any suitable radio access
`technology.
`[0044]
`It is contemplated that the system 100 may use
`multiple channel access functionality, including for example
`schemes in which the base stations 170 and user equipment
`ll0A-ll0C are configured to implement the Long Term
`Evolution wireless communication standard (LTE), LTE
`Advanced (LTE-A), and/or LTE Broadcast (LTE-B).
`[0045]
`In other embodiments, the base stations 170 and
`user equipment ll0A-ll0C are configured to implement
`UMTS, HSPA, or HSPA+ standards and protocols. Of
`course, other multiple access schemes and wireless proto(cid:173)
`cols may be utilized.
`[0046] The RANs 120A-120B are in communication with
`the core network 130 to provide the user equipment ll0A(cid:173)
`ll0C with voice, data, application, Voice over Internet
`Protocol (VoIP), or other services. As appreciated, the RANs
`120A-120B and/or the core network 130 may be in direct or
`indirect communication with one or more other RANs (not
`shown). The core network 130 may also serve as a gateway
`access for other networks (such as PSTN 140, Internet 150,
`and other networks 160). In addition, some or all of the user
`equipment ll0A-ll0C may include functionality for com(cid:173)
`municating with different wireless networks over different
`wireless links using different wireless technologies and/or
`protocols.
`[0047] The RANs 120A-120B may also include millime(cid:173)
`ter and/or microwave access points (APs). The APs may be
`part of the base stations 170 or may be located remote from
`the base stations 170. The APs may include, but are not
`limited to, a connection point ( a mm W CP) or a base station
`170 capable of mm W communication ( e.g., a mm W base
`station). The mm W APs may transmit and receive signals in
`a frequency range, for example, from 6 GHz to 100 GHz, but
`are not required to operate throughout this range. As used
`herein, the term base station is used to refer to a base station
`and/or a wireless access point.
`[0048] Although FIG. 1 illustrates one example of a com(cid:173)
`munication system, various changes may be made to FIG. 1.
`For example, the communication system 100 could include
`
`any number of user equipment, base stations, networks, or
`other components in any suitable configuration. It is also
`appreciated that the term user equipment may refer to any
`type of wireless device communicating with a radio network
`node in a cellular or mobile communication system. Non(cid:173)
`limiting examples of user equipment are a target device,
`device-to-device (D2D) user equipment, machine type user
`equipment or user equipment capable of machine-to-ma(cid:173)
`chine (M2M) communication, laptops, PDA, iPad, Tablet,
`mobile terminals, smart phones, laptop embedded equipped
`(LEE), laptop mounted equipment (LME) and USB dongles.
`[0049] FIG. 2 illustrates a base station with transmitting
`and receiving beams according to an example embodiment.
`The base station 202 manages a cell 204 divided into one or
`more sectors as its service coverage area and forms multiple
`transmit/receive (Tx/Rx) beams BM1-BM7 using beam(cid:173)
`forming schemes. Beamforming generally refers to use of
`multiple antennas to control the direction of a wavefront by
`appropriately weighting the magnitude and phase of indi(cid:173)
`vidual antenna signals. Beamforming schemes includes, but
`are not limited to, digital beamforming (e.g., Transmit (Tx)
`pre-Inverse Fast Fourier Transform (pre-IFFT) beamform(cid:173)
`ing/Receive (Rx) post-Fast Fourier Transform (post-FFT)
`beamforming), analog beamforming (e.g., Tx post-IFFT
`beamforming/Rx pre-FFT beamforming), or a combination
`thereof. The base station 202 transmits the beamformed
`signals by sweeping them simultaneously or successively,
`for example, beginning with beam BM! and ending with
`BM7.
`[0050] User equipment (UE), such as user equipment
`ll0A-ll0C (FIG. 1), located within the cell of the base
`station 202 may be configured to receive signals omni(cid:173)
`directionally without supporting Rx beamforming, receive
`signals while supporting Rx beamforming by using one
`beamforming pattern each time, or receive signals while
`supporting Rx beamforming by simultaneously using a
`plurality of beamforming patterns in different directions.
`If the user equipment ll0A-ll0C does not support
`[0051]
`Rx beamforming, the user equipment ll0A-ll0C measures
`the channel quality of a reference signal (RS) in each
`transmission beam and reports the measurements to the base
`station 202. The station 202 selects the best beam for the
`user equipment ll0A-ll0C from among a plurality of Tx
`beams. If the user equipment ll0A-ll0C is configured to
`support Rx beamforming, the user equipment ll0A-ll0C
`measures the channel qualities of multiple Tx beams
`received from the base station 202 for each reception beam
`pattern and reports a total or some high-ranked measure(cid:173)
`ments of all Tx-Rx beam pairs to the base station 202. The
`base station 202 may allocate an appropriate Tx beam to the
`user equipment ll0A-ll0C. If the user equipment ll0A(cid:173)
`ll0C is capable of receiving a plurality of Tx beams from
`the base station 202 or supporting a plurality of base station
`Tx-user equipment Rx beam pairs, the base station 202 may
`select a beam, taking into account diversity transmission
`through repeated transmission or simultaneous transmission.
`[0052] FIG. 3 illustrates physical channels and transmit(cid:173)
`ting signals on the physical channels in accordance with
`FIG. 2. When user equipment ll0A-ll0C (FIG. 1) is pow(cid:173)
`ered on or enters a new cell, such as cell 204 (FIG. 2), the
`user equipment performs an initial cell search 302. The
`initial cell search 302 involves acquisition of synchroniza(cid:173)
`tion to a base station, such as gNB 202. Specifically, the user
`equipment synchronizes its timing to the gNB 202 and
`
`Samsung Exhibit 1004, Page 14 of 22
`
`

`

`US 2019/0053294 Al
`
`Feb. 14,2019
`
`4
`
`acquires a cell Identifier (ID) and other information by
`receiving a Primary Synchronization Channel (P-SCH) and
`a Secondary Synchronization Channel (S-SCH) from the
`gNB 202. Subsequently, the user equipment ll0A-ll0C
`may acquire information broadcast in the cell by receiving
`a Physical Broadcast Channel (PBCH) from the gNB 202.
`During the initial cell search, the user equipment 11 0A 11 0C
`may monitor a downlink (DL) channel state by receiving a
`do unlink reference Signal (DL RS).
`[0053] After the initial cell search, the user equipment
`ll0A-ll0C may acquire detailed system information at 304
`by receiving a Physical Downlink Control Channel (PD(cid:173)
`CCH) and receiving a Physical Downlink Shared Channel
`(PDSCH) based on information included in the PDCCH.
`[0054]
`If the user equipment ll0A-ll0C initially accesses
`the gNB 202 or has no radio resources for signal transmis(cid:173)
`sion to the gNB 202, the user equipment ll0A-ll0C may
`perform a random access procedure at 306 with the gNB
`202. During the random access procedure 306,
`[0055] Upon completion of the above process, the user
`equipment ll0A-ll0C may receive a PDCCH and/or a
`PDSCH from the gNB 202 and transmit a Physical Uplink
`Shared Channel (PUSCH) and/or a PUCCH to the gNB 202,
`which is a general DL and UL signal transmission procedure
`at 308. Specifically; the user equipment ll0A-ll0C receives
`Downlink Control Information (DCI) on a PDCCH. The
`DCI includes, for example, control information such as
`resource allocation information for the user equipment
`ll0A-ll0C.
`[0056] Control information that the user equipment ll0A(cid:173)
`ll0C transmits to the gNB 202 on the uplink (UL) channel
`or receives from the gNB 202 on the DL channel includes a
`DL/UL ACKnowledgment/Negative ACKnowledgment
`(ACK/NACK) signal, a Channel Quality Indicator (CCM; a
`Precoding Matrix Index (PMI), a Rank Indicator (RI); etc.
`The control information, such as a CQI, a PMI, an RI, etc.,
`may be transmitted on a PUSCH and/or a PUCCH.
`[0057] FIGS. 4A and 4B illustrate examples of beam
`failure between a base station and user equipment. As
`illustrated, base station 402 is in communication with user
`equipment 404, in which the base station 402 and user
`equipment 404 communicate via DL beam pairs and UL
`beam pairs. In one embodiment, the DL beam pair fails
`(FIG. 4A). In another embodiment, the DL/UL beam pair
`fails (FIG. 4B).
`[0058] Before establishing a communication or beam pair
`link with a base station 402, user equipment 404 generally
`performs cell acquisition and synchronization. The cell
`acquisition step typically involves receiving a synchroniza(cid:173)
`tion signal from base station 402. In a high frequency wave
`band, beamforming may be applied to synchronization sig(cid:173)
`nals ( otherwise, the distance at which the synchronization
`signal can be received is much smaller than the distance at
`which the beamformed data channels can be received). If the
`synchronization signals are beamformed, only user equip(cid:173)
`ment 404 within the narrow angle covered by the beam are
`able to receive the synchronization signal. To ensure that
`user equipment 404 receives the synchronization signal, the
`base station 402 may "beam-sweep" the synchronization
`signal having the narrow angle covered by the beam. Beam
`sweeping refers to rotating the direction of the beam to cover
`all directions such that it may be detected in areas of the
`beam sweep by the user equipment 404. To receive the
`synchronization signal, the user equipment 404 may also
`
`need to rotate the direction in which it searches for the
`synchronization signal. Rotation allows the antennas (which
`may be phase-arrayed) of the base station 402 and user
`equipment 404 to be mutually aligned.
`[0059] The cell acquisition and synchronization becomes
`even more complicated if the user equipment 404 is moving,
`as the direction of arrival of the synchronization signal beam
`continually changes. Under these circumstances, the user
`equipment 404 may try to locate multiple base stations 402
`to identify multiple cells suitable for service. However,
`sweeping procedures to identify a group of base stations can
`mean a substantial increase in the cell acquisition duration.
`[0060] At higher frequencies (e.g., microwave and milli(cid:173)
`meter-wave spectrum), beamformed transmissions are an
`important feature to overcome higher path losses. Beam(cid:173)
`forming may be applied to user equipment specific DL and
`UL data transmissions, and also to common channels such as
`synchronization and control channels on the DL and random
`access channels on the UL.
`[0061] Since the antenna arrangements (FIG. 4C) at the
`base station 402 and at the user equipment 404 allow
`beamforming, there may be multiple beams in multiple
`directions for transmission and reception at each of the base
`stations 402 and the user equipment 404. For example, there
`may be any number of beam directions for reception at the
`user equipment 404 and any number of directions for beam
`transmission at the base station 402.
`In the embodiment of FIG. 4A, a single or unidi(cid:173)
`[0062]
`rectional transmission and reception beam pair are illus(cid:173)
`trated, whereas in FIG. 4B, multiple directions or onmidi(cid:173)
`rectional
`transmission and reception beam pairs are
`illustrated. In either case, the system may determine the
`"best" beam pair(s) ( e.g., the beam with the strongest signal,
`fastest DL/UL speed, etc.) for transmission and reception
`among the various reception and transmission directions. In
`this regard, a signal received from the base station 402 from
`a particular receive direction can be identified as having a
`corresponding transmit direction to transmit to the base
`station 402.
`[0063] Beam pair transmission and reception (in the DL
`and UL beams) use multi