U.S. patent application number 16/989256 was filed with the patent office on 2020-11-26 for communication method and communications apparatus.
The applicant listed for this patent is Huawei Technologies Co., Ltd.. Invention is credited to Le Yan, Qinghai Zeng, Hongping Zhang.
Application Number | 20200374938 16/989256 |
Document ID | / |
Family ID | 1000005005128 |
Filed Date | 2020-11-26 |
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United States Patent
Application |
20200374938 |
Kind Code |
A1 |
Yan; Le ; et al. |
November 26, 2020 |
Communication Method and Communications Apparatus
Abstract
Embodiments of this application provide a communication method
and a communications apparatus. The method includes: receiving
identification information of N beams of a target cell and random
access channel configurations of M beams in the N beams, where N
and M are positive integers; and determining a beam for accessing
based on signal quality or signal strength of L beams in the N
beams, the identification information of the N beams, and the
random access channel configurations of the M beams, where L is a
nonnegative integer.
Inventors: |
Yan; Le; (Shanghai, CN)
; Zeng; Qinghai; (Shanghai, CN) ; Zhang;
Hongping; (Shanghai, CN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Huawei Technologies Co., Ltd. |
Shenzhen |
|
CN |
|
|
Family ID: |
1000005005128 |
Appl. No.: |
16/989256 |
Filed: |
August 10, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16536003 |
Aug 8, 2019 |
10785805 |
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16989256 |
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PCT/CN2018/091540 |
Jun 15, 2018 |
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16536003 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 74/0833 20130101;
H04B 7/0695 20130101; H04W 36/30 20130101; H04W 36/06 20130101 |
International
Class: |
H04W 74/08 20060101
H04W074/08; H04W 36/30 20060101 H04W036/30; H04W 36/06 20060101
H04W036/06; H04B 7/06 20060101 H04B007/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 16, 2017 |
CN |
201710459115.0 |
Claims
1. A method, comprising: receiving, by a terminal, random access
channel configurations corresponding to M beams of a target cell,
wherein M is a positive integer, and each random access channel
configuration of the random access channel configurations of the M
beams comprises a respective preamble index and a respective
time-frequency resource configuration; when the M beams comprise at
least one beam whose signal strength is greater than or equal to a
first beam signal strength threshold, determining, by the terminal,
to use a first beam of the at least one beam for a random access
procedure in the target cell; and when a signal strength of each of
the M beams is less than the first beam signal strength threshold,
determining, by the terminal, to use a second beam of L beams for
the random access procedure in the target cell, wherein a signal
strength of the second beam is greater than or equal to the first
beam signal strength threshold, L is a nonnegative integer, and the
L beams are all beams whose signal strength is detected.
2. The method according to claim 1, further comprising: receiving
the first beam signal strength threshold.
3. The method according to claim 2, wherein receiving the first
beam signal strength threshold comprises: receiving the first beam
signal strength threshold through a radio resource control (RRC)
connection reconfiguration message.
4. The method according to claim 1, further comprising: when a
respective signal strength of each of the L beams and each of the M
beams is less than the first beam signal strength threshold, or
none of the M beams is found, performing the following: determining
to use an earliest found beam for the random access procedure in
the target cell; determining to use a beam with a highest signal
strength for the random access procedure in the target cell;
determining to use a randomly found beam for the random access
procedure in the target cell; or determining to use a beam with a
highest priority for the random access procedure in the target
cell.
5. The method according to claim 1, wherein determining to use the
first beam for the random access procedure in the target cell
comprises: selecting the first beam based on a priority order of
the at least one beam whose signal strength is greater than or
equal to the first beam signal strength threshold.
6. The method according to claim 1, wherein identification
information of each beam comprises respective synchronization
signal block identification information of the respective beam or
respective channel state information-reference signal
identification information of the respective beam.
7. The method according to claim 6, wherein a priority of a beam
that is used to transmit channel state information-reference signal
identification information is higher than that of a beam that is
used to transmit synchronization signal block identification
information.
8. An apparatus, comprising: a first circuitry, configured to:
receive random access channel configurations corresponding to M
beams of a target cell, wherein M is a positive integer, and each
random access channel configuration of the random access channel
configurations of the M beams comprises a respective preamble index
and a respective time-frequency resource configuration; and a
second circuitry, configured to: when the M beams comprise at least
one beam whose signal strength is greater than or equal to a first
beam signal strength threshold, determine to use a first beam of
the at least one beam for a random access procedure in the target
cell; and when a signal strength of each of the M beams is less
than the first beam signal strength threshold, determine to use a
second beam of L beams for the random access procedure in the
target cell, wherein a signal strength of the second beam is
greater than or equal to the first beam signal strength threshold,
L is a nonnegative integer, and the L beams are all beams whose
signal strength is detected.
9. The apparatus according to claim 8, wherein the first circuitry
is further configured to receive the first beam signal strength
threshold.
10. The apparatus according to claim 9, wherein the first beam
signal strength threshold is carried in a radio resource control
(RRC) connection reconfiguration message.
11. The apparatus according to claim 8, wherein the second
circuitry is further configured to: when a respective signal
strength of each of the L beams and each of the M beams is less
than the first beam signal strength threshold, or none of the M
beams is found, perform the following: determine to use an earliest
found beam for the random access procedure in the target cell;
determine to use a beam with a highest signal strength for the
random access procedure in the target cell; determine to use a
randomly found beam for the random access procedure in the target
cell; or determine to use a beam with a highest priority for the
random access procedure in the target cell.
12. The apparatus according to claim 8, wherein the second
circuitry is further configured to: select the first beam based on
a priority order of the at least one beam whose signal strength is
greater than or equal to the first beam signal strength
threshold.
13. The apparatus according to claim 8, wherein identification
information of each beam comprises respective synchronization
signal block identification information of the respective beam or
respective channel state information-reference signal
identification information of the respective beam.
14. The apparatus according to claim 13, wherein a priority of a
beam that is used to transmit channel state information-reference
signal identification information is higher than that of a beam
that is used to transmit synchronization signal block
identification information.
15. A non-transitory computer readable storage medium, wherein the
non-transitory computer readable storage medium stores a program to
be executed by a processor, the program including instructions for:
receiving random access channel configurations corresponding to M
beams of a target cell, wherein M is a positive integer, and each
random access channel configuration of the random access channel
configurations of the M beams comprises a respective preamble index
and a respective time-frequency resource configuration; when the M
beams comprise at least one beam whose signal strength is greater
than or equal to a first beam signal strength threshold,
determining to use a first beam of the at least one beam for a
random access procedure in the target cell; and when a signal
strength of each of the M beams is less than the first beam signal
strength threshold, determining to use a second beam of L beams for
the random access procedure in the target cell, wherein a signal
strength of the second beam is greater than or equal to the first
beam signal strength threshold, L is a nonnegative integer, and the
L beams are all beams whose signal strength is detected.
16. The medium according to claim 15, wherein the program further
includes instructions for: receiving the first beam signal strength
threshold.
17. The medium according to claim 15, wherein the program further
includes instructions for: when a respective signal strength of
each of the L beams and each of the M beams is less than the first
beam signal strength threshold, or none of the M beams is found,
performing the following: determining to use an earliest found beam
for the random access procedure in the target cell; determining to
use a beam with a highest signal strength for the random access
procedure in the target cell; determining to use a randomly found
beam for the random access procedure in the target cell; or
determining to use a beam with a highest priority for the random
access procedure in the target cell.
18. The medium according to claim 15, wherein the program further
includes instructions for: selecting the first beam based on a
priority order of the at least one beam whose signal strength is
greater than or equal to the first beam signal strength
threshold.
19. The medium according to claim 15, wherein identification
information of each beam comprises respective synchronization
signal block identification information of the respective beam or
respective channel state information-reference signal
identification information of the respective beam.
20. The medium according to claim 19, wherein a priority of a beam
that is used to transmit the channel state information-reference
signal identification information is higher than that of a beam
that is used to transmit the synchronization signal block
identification information.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of U.S. patent
application Ser. No. 16/536,003, filed on Aug. 8, 2019, which is a
continuation of International Application No. PCT/CN2018/091540,
filed on Jun. 15, 2018. The International Application claims
priority to Chinese Patent Application No. 201710459115.0, filed on
Jun. 16, 2017. All of the afore-mentioned patent applications are
hereby incorporated by reference in their entireties.
TECHNICAL FIELD
[0002] Embodiments of this application relate to the field of
communications technologies, and in particular, to a communication
method and a communications apparatus.
BACKGROUND
[0003] Mobile communications not only pursues maximization of a
capacity, but also needs a broader coverage area. That is, a
terminal that moves to anywhere needs to be covered by a wireless
network signal. When a terminal moves towards another cell from a
serving cell, to ensure service continuity of the terminal, the
terminal needs to be handed over from the current serving cell to
the another cell.
[0004] Currently, a serving cell handover process of a terminal in
an LTE system is described as follows: A source base station
(Source eNB, SeNB) determines to perform a serving cell handover on
a terminal based on a measurement report reported by the terminal
and initiates a handover request to a target base station (Target
eNB, TeNB). After the SeNB obtains a handover request
acknowledgement message from the TeNB, the SeNB sends a handover
message to the terminal. The terminal initiates a random access
process to the target base station based on an identifier of a
target cell carried in the handover message, to obtain a TA value
and an uplink resource, and sends a handover complete message to
the target base station on the uplink resource.
[0005] However, a high-frequency technology is introduced in a
current 5G system. During data transmission at a high frequency, a
relatively large transmission loss is usually caused. To ensure
effective service transmission, a high-frequency cell uses a
beamforming technology to perform communication, that is, each
high-frequency cell has a plurality of different beams used for
communication. When a handover is performed on a terminal, how the
terminal selects a beam for access needs an urgent solution.
SUMMARY
[0006] Embodiments of this application provide a communication
method and a communications apparatus, to provide a proper beam
access solution.
[0007] According to a first aspect, an embodiment of this
application provides a communication method. The method includes
receiving identification information of N beams of a target cell
and random access channel configurations of M beams in the N beams,
where N and M are positive integers. The method also includes
determining a beam for accessing based on signal quality or signal
strength of L beams in the N beams, the identification information
of the N beams, and the random access channel configurations of the
M beams, where L is a nonnegative integer.
[0008] In a possible design, the determining a beam for accessing
based on signal strength of L beams in the N beams, the
identification information of the N beams, and the random access
channel configurations of the M beams includes: determining the
beam for accessing based on the signal strength of the L beams in
the N beams, strength threshold information, the identification
information of the N beams, and the random access channel
configurations of the M beams.
[0009] In a possible design, the method further includes: receiving
the strength threshold information.
[0010] In a possible design, the strength threshold information
includes a first beam signal strength threshold or strength
threshold indication information, the strength threshold indication
information is used to indicate a relationship between the first
beam signal strength threshold and a second beam signal strength
threshold, and the second beam signal strength threshold is a beam
signal strength threshold carried in measurement configuration
information.
[0011] In a possible design, the determining the beam for accessing
based on the signal strength of the L beams in the N beams,
strength threshold information, the identification information of
the N beams, and the random access channel configurations of the M
beams includes: determining, based on the signal strength of the L
beams in the N beams, the strength threshold information, the
identification information of the N beams, and the random access
channel configurations of the M beams, a beam whose signal strength
is greater than or equal to the first beam signal strength
threshold from the M beams as the beam for accessing the target
cell. Therefore, the beam that is for accessing the target cell and
that is determined by the terminal has a random access channel
configuration and high signal strength. In this way, a success rate
of accessing the target cell by the terminal is higher.
[0012] In a possible design, the determining the beam for accessing
based on the signal strength of the L beams in the N beams,
strength threshold information, the identification information of
the N beams, and the random access channel configurations of the M
beams includes: when signal strength of each of the M beams is less
than the first beam signal strength threshold, determining the beam
for accessing, from the M beams based on the identification
information of the N beams and the random access channel
configurations of the M beams, the beam for accessing the target
cell. Therefore, the beam that is for accessing the target cell and
that is determined by the terminal has the random access channel
configuration. In this way, a success rate of accessing the target
cell by the terminal is high.
[0013] In a possible design, the determining the beam for accessing
based on the signal strength of the L beams in the N beams,
strength threshold information, the identification information of
the N beams, and the random access channel configurations of the M
beams includes: when signal strength of each of the M beams is less
than the first beam signal strength threshold, determining, based
on the identifiers of the N beams, the signal strength of the L
beams, and the strength threshold information, a beam whose signal
strength is greater than or equal to the first beam signal strength
threshold from the L beams as the beam for accessing the target
cell. Therefore, the beam that is for accessing the target cell and
that is determined by the terminal belongs to the L beams. In this
way, a success rate of accessing the target cell by the terminal is
high.
[0014] In a possible design, the determining the beam for accessing
based on the signal strength of the L beams in the N beams,
strength threshold information, the identification information of
the N beams, and the random access channel configurations of the M
beams includes: determining, based on the signal strength of the L
beams, the strength threshold information, the identification
information of the N beams, a priority order of the N beams, and
the random access channel configurations of the M beams, the beam
for accessing the target cell.
[0015] In a possible design, the determining a beam for accessing
based on signal strength of L beams in the N beams, the
identification information of the N beams, and the random access
channel configurations of the M beams includes: when none of the M
beams is found, determining, based on the identification
information of the N beams, a beam with highest signal strength in
the L beams as the beam for accessing the target cell. Therefore,
the terminal determines that the beam for accessing the target cell
has a strongest signal in the L beams. In this way, a success rate
of accessing the target cell by the terminal is high.
[0016] In a possible design, the identification information of the
N beams includes synchronization signal block identification
information and/or channel state information-reference signal
identification information, where the determining a beam for
accessing based on signal strength of L beams in the N beams, the
identification information of the N beams, and the random access
channel configurations of the M beams includes: determining the
beam for accessing based on the signal strength of the L beams in
the N beams, the strength threshold information, the identification
information of the N beams, that a priority of a beam whose
identification information is the channel state
information-reference signal identification information is higher
than that of a beam whose identification information is the
synchronization signal block identification information, and the
random access channel configurations of the M beams.
[0017] In a possible design, if none of the N beams is found,
signal strength of the L beams or signal strength of each of the M
beams is less than the first beam signal strength threshold, or
none of the M beams is found, the method further includes:
determining the first found beam as the beam for accessing,
determining a beam with highest signal strength as the beam for
accessing, randomly determining a found beam as the beam for
accessing, or determining a beam with a highest priority in found
beams as the beam for accessing. Therefore, the terminal
determines, in a relatively flexible manner, the beam for accessing
the target cell.
[0018] In a possible design, the random access channel
configuration includes a preamble index and a time-frequency
resource configuration.
[0019] According to a second aspect, an embodiment of this
application provides a communication method. The method includes
receiving, by a first network device, identification information of
N beams of a target cell and random access channel configurations
of M beams in the N beams that are sent by a second network device,
where N and M are positive integers. The method also includes
sending, by the first network device, the identification
information of the N beams and the random access channel
configurations of the M beams to a terminal.
[0020] In a possible design, the method further includes:
receiving, by the first network device, serving beam change
information of the terminal that is within a predetermined time
period and that is sent by the terminal; and sending, by the first
network device, the serving beam change information to the second
network device, where the serving beam change information is used
by the second network device to determine a validity period of the
random access channel configurations of the M beams.
[0021] In a possible design, the method further includes:
receiving, by the first network device, serving beam change
information of the terminal that is within a predetermined time
period and that is sent by the terminal; determining, by the first
network device, a validity period of the random access channel
configurations of the M beams based on the serving beam change
information; and sending, by the first network device, the validity
period of the random access channel configurations of the M beams
to the second network device.
[0022] In a possible design, the random access channel
configuration includes a preamble index and a time-frequency
resource configuration.
[0023] In a possible design, the method further includes: sending,
by the first network device, strength threshold information or
quality threshold information of a beam signal to the terminal
through a handover message.
[0024] According to a third aspect, an embodiment of this
application provides a communication method. The method includes
sending, by a second network device, identification information of
N beams of a target cell and random access channel configurations
of M beams in the N beams to a first network device, where N and M
are positive integers.
[0025] Optionally, the method further includes: receiving, by the
second network device, serving beam change information of a
terminal that is within a predetermined time period and that is
sent by the first network device; determining, by the second
network device, a validity period of the random access channel
configurations of the M beams based on the serving beam change
information; and when the validity period expires, releasing, by
the second network device, the random access channel configurations
of the M beams.
[0026] Optionally, the method further includes: receiving, by the
second network device, the validity period of the random access
channel configurations of the M beams that is sent by the first
network device; and when the validity period expires, releasing, by
the second network device, the random access channel configurations
of the M beams.
[0027] Optionally, the method further includes: sending, by the
second network device, strength threshold information or quality
threshold information of a beam signal to the terminal through
system information.
[0028] According to a fourth aspect, an embodiment of this
application provides a communications apparatus. The apparatus
includes a receiving module, configured to receive identification
information of N beams of a target cell and random access channel
configurations of M beams in the N beams, where N and M are
positive integers. The apparatus also includes a processing module,
configured to determine a beam for accessing based on signal
quality or signal strength of L beams in the N beams, the
identification information of the N beams, and the random access
channel configurations of the M beams, where L is a nonnegative
integer.
[0029] In a possible design, the processing module is specifically
configured to determine the beam for accessing based on the signal
strength of the L beams in the N beams, strength threshold
information, the identification information of the N beams, and the
random access channel configurations of the M beams.
[0030] In a possible design, the receiving module is further
configured to receive the strength threshold information.
[0031] In a possible design, the strength threshold information
includes a first beam signal strength threshold or strength
threshold indication information, the strength threshold indication
information is used to indicate a relationship between the first
beam signal strength threshold and a second beam signal strength
threshold, and the second beam signal strength threshold is a beam
signal strength threshold carried in measurement configuration
information.
[0032] In a possible design, the processing module is specifically
configured to determine, based on the signal strength of the L
beams in the N beams, the strength threshold information, the
identification information of the N beams, and the random access
channel configurations of the M beams, a beam whose signal strength
is greater than or equal to the first beam signal strength
threshold from the M beams as the beam for accessing the target
cell.
[0033] In a possible design, the processing module is specifically
configured to: when signal strength of each of the M beams is less
than the first beam signal strength threshold, determine, from the
M beams based on the identification information of the N beams and
the random access channel configurations of the M beams, the beam
for accessing the target cell.
[0034] In a possible design, the processing module is specifically
configured to: when signal strength of each of the M beams is less
than the first beam signal strength threshold, determine, based on
the identifiers of the N beams, the signal strength of the L beams,
and the strength threshold information, a beam whose signal
strength is greater than or equal to the first beam signal strength
threshold from the L beams as the beam for accessing the target
cell.
[0035] In a possible design, the processing module is specifically
configured to determine, based on the signal strength of the L
beams, the strength threshold information, the identification
information of the N beams, a priority order of the N beams, and
the random access channel configurations of the M beams, the beam
for accessing the target cell.
[0036] In a possible design, the processing module is specifically
configured to: when none of the M beams is found, determine, based
on the identification information of the N beams, a beam with
highest signal strength in the L beams as the beam for accessing
the target cell.
[0037] In a possible design, the identification information of the
N beams includes synchronization signal block identification
information and/or channel state information-reference signal
identification information, where the processing module is
specifically configured to determine the beam for accessing based
on the signal strength of the L beams in the N beams, the strength
threshold information, the identification information of the N
beams, that a priority of a beam whose identification information
is the channel state information-reference signal identification
information is higher than that of a beam whose identification
information is the synchronization signal block identification
information, and the random access channel configurations of the M
beams.
[0038] In a possible design, the processing module is further
configured to: if none of the N beams is found, signal strength of
the L beams or signal strength of each of the M beams is less than
the first beam signal strength threshold, or none of the M beams is
found, determine the first found beam as the beam for accessing,
determine a beam with highest signal strength as the beam for
accessing, randomly determine a found beam as the beam for
accessing, or determine a beam with a highest priority in found
beams as the beam for accessing.
[0039] In a possible design, the random access channel
configuration includes a preamble index and a time-frequency
resource configuration.
[0040] It should be noted that the communications apparatus in the
fourth aspect may be a terminal, or may be a chip inside a
terminal.
[0041] According to a fifth aspect, an embodiment of this
application provides a communications apparatus. The apparatus
includes a receiving module, configured to receive identification
information of N beams of a target cell and random access channel
configurations of M beams in the N beams that are sent by a second
network device, where N and M are positive integers. The apparatus
also includes a sending module, configured to send the
identification information of the N beams and the random access
channel configurations of the M beams to a terminal.
[0042] In a possible design, the receiving module is further
configured to receive serving beam change information of the
terminal that is within a predetermined time period and that is
sent by the terminal; and the sending module is further configured
to send the serving beam change information to the second network
device, where the serving beam change information is used by the
second network device to determine a validity period of the random
access channel configurations of the M beams.
[0043] In a possible design, the communications apparatus further
includes a processing module, where the receiving module is further
configured to receive serving beam change information of the
terminal that is within a predetermined time period and that is
sent by the terminal; the processing module is configured to
determine a validity period of the random access channel
configurations of the M beams based on the serving beam change
information; and the sending module is further configured to send
the validity period of the random access channel configurations of
the M beams to the second network device.
[0044] In a possible design, the random access channel
configuration includes a preamble index and a time-frequency
resource configuration; and the sending module is further
configured to send strength threshold information or quality
threshold information of a beam signal to the terminal through a
handover message.
[0045] It should be noted that the communications apparatus in the
fifth aspect may be a network device, or may be a chip inside a
network device.
[0046] According to a sixth aspect, an embodiment of this
application provides a communications apparatus. The apparatus
includes a sending module, configured to send identification
information of N beams of a target cell and random access channel
configurations of M beams in the N beams to a first network device,
where N and M are positive integers.
[0047] In a possible design, the network device further includes a
receiving module and a processing module, where the receiving
module is configured to receive serving beam change information of
a terminal that is within a predetermined time period and that is
sent by the first network device; and the processing module is
configured to: determine a validity period of the random access
channel configurations of the M beams based on the serving beam
change information; and after the validity period expires, release
the random access channel configurations of the M beams.
[0048] In a possible design, the network device further includes a
receiving module and a processing module, where the receiving
module is configured to receive the validity period of the random
access channel configurations of the M beams that is sent by the
first network device; and the processing module is configured to:
after the validity period expires, release the random access
channel configurations of the M beams.
[0049] In a possible design, the sending module is further
configured to send strength threshold information or quality
threshold information of a beam signal to the terminal through
system information.
[0050] It should be noted that the communications apparatus in the
sixth aspect may be a network device, or may be a chip inside a
network device.
[0051] According to a seventh aspect, an embodiment of this
application provides a terminal, including a processor and a
transceiver. The processor and the transceiver are configured to
perform the communication method according to any one of the
embodiments of this application in the first aspect.
[0052] According to an eighth aspect, an embodiment of this
application provides a network device, including a processor and a
transceiver. The processor and the transceiver are configured to
perform the communication method according to any one of the
embodiments of this application in the second aspect.
[0053] According to a ninth aspect, an embodiment of this
application provides a network device, including a processor and a
transceiver. The processor and the transceiver are configured to
perform the communication method according to any one of the
embodiments of this application in the third aspect.
[0054] According to a tenth aspect, an embodiment of this
application provides a computer readable storage medium. When an
instruction in the storage medium is executed by a processor of a
communications apparatus, the communications apparatus can perform
the communication method according to the embodiments of this
application in the first aspect.
[0055] According to an eleventh aspect, an embodiment of this
application provides a computer readable storage medium. When an
instruction in the storage medium is executed by a processor of a
communications apparatus, the communications apparatus can perform
the communication method according to the embodiments of this
application in the second aspect.
[0056] According to a twelfth aspect, an embodiment of this
application provides a computer readable storage medium. When an
instruction in the storage medium is executed by a processor of a
communications apparatus, the communications apparatus can perform
the communication method according to the embodiments of this
application in the third aspect.
[0057] According to the communication method and the communications
apparatus in the embodiments of this application, the terminal
receives the identification information of the N beams and the
random access channel configurations of the M beams in the N beams,
and the terminal determines the beam for accessing based on the
signal quality or signal strength of the L beams in the N beams,
the identification information of the N beams, and the random
access channel configurations of the M beams, providing a proper
beam for accessing determining solution. Further, the beam for
accessing in the embodiments is determined by the terminal based on
the signal quality or signal strength of the L beams in the N beams
and the received random access channel configurations of the M
beams. Therefore, the beam for accessing determined in this manner
can increase an access success rate of the terminal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0058] FIG. 1 is a schematic diagram of a communications system
according to an embodiment of this application;
[0059] FIG. 2 is a flowchart of a communication method according to
Embodiment 1 of this application;
[0060] FIG. 3 is a flowchart of a communication method according to
Embodiment 2 of this application;
[0061] FIG. 4 is a flowchart of a communication method according to
Embodiment 3 of this application;
[0062] FIG. 5 is a schematic structural diagram of a communications
apparatus according to an embodiment of this application;
[0063] FIG. 6 is a schematic structural diagram of a terminal
according to an embodiment of this application;
[0064] FIG. 7 is a schematic structural diagram of a communications
apparatus according to an embodiment of this application;
[0065] FIG. 8 is a schematic structural diagram of a network device
according to an embodiment of this application;
[0066] FIG. 9 is a schematic structural diagram of a communications
apparatus according to an embodiment of this application; and
[0067] FIG. 10 is a schematic structural diagram of a network
device according to an embodiment of this application.
DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
[0068] FIG. 1 is a schematic diagram of a communications system
according to an embodiment of this application. As shown in FIG. 1,
the communications system includes at least two network devices and
at least one terminal. The at least two network devices communicate
with the at least one terminal by using a technical solution
provided in the following embodiments of this application. FIG. 1
shows one terminal and two network devices: a first network device
and a second network device.
[0069] Some terms in this application are explained in the
following, to help a person skilled in the art have a better
understanding:
[0070] A network device is also referred to as a radio access
network (RAN) device, is a device that connects a terminal to a
radio network, and may be an evolved NodeB (eNB or eNodeB) in long
term evolution (LTE), a relay node, an access point, or a gNB in a
5G network, for example, a transmission and reception point (TRP)
or a controller. This is not limited herein.
[0071] A terminal may be a wireless or wired terminal. The wireless
terminal may be a device having a wireless receiving and sending
function, and may be deployed on land, including an indoor or
outdoor terminal, a handheld terminal, or an in-vehicle terminal;
or may be deployed on the water (for example, in a steamship); or
may be deployed in the air (for example, on an airplane, on a
balloon, or on a satellite). The terminal may be a mobile phone a
tablet computer (Pad), a computer having a wireless receiving and
sending function, a virtual reality (VR) terminal, an augmented
reality (AR) terminal, a wireless terminal in industrial control, a
wireless terminal in self driving, a wireless terminal in
telemedicine, a wireless terminal in smart grid, a wireless
terminal in transportation safety, a wireless terminal in smart
city, a wireless terminal in smart home, or the like. This is not
limited herein.
[0072] In this embodiment of this application, beams may include a
transmit beam and a receive beam. The transmit beam may be signal
strength distribution formed in different spatial directions after
signals are transmitted through an antenna, and the receive beam
may be signal strength distribution formed in different spatial
directions after wireless signals are received through an antenna.
It can be understood that one or more antenna ports for one beam
may also be considered as an antenna port set. In other words, one
antenna port set includes at least one antenna port.
[0073] Specifically, the beam may refer to a precoding vector
having specific energy transmission directivity, and the precoding
vector can be identified by using identification information. The
energy transmission directivity means that a signal obtained by
performing precoding processing by using the precoding vector is
received at a relatively high receive power in a specific spatial
location, for example, the receive power meets a reception
demodulation signal-to-noise ratio. However, a signal obtained by
performing precoding processing by using the precoding vector is
received at a relatively low power in another spatial location, for
example, the receive power does not meet a reception demodulation
signal-to-noise ratio. Different communications devices may have
different precoding vectors, that is, corresponding to different
beams. One communications device may use one or more of a plurality
of different precoding vectors at a same time point based on a
configuration or capability of the communications device, that is,
one or more beams may be formed simultaneously. The beam may be
understood as a spatial resource. The beam may be identified by
using identification information. Optionally, the identification
information may be corresponding to a configured corresponding
resource identifier (ID) of user equipment. For example, the
identification information may be corresponding to a configured ID
or resource of a channel state information-reference signal
(CSI-RS), or may be corresponding to a configured ID or resource of
an uplink sounding reference signal (SRS). Alternatively,
optionally, the identification information may be identification
information explicitly or implicitly carried on a signal or channel
that is carried on a beam. For example, the identification
information includes but is not limited to identification
information of the beam indicated by a synchronization signal or
broadcast channel that is sent by using the beam, and includes but
is not limited to identification information of the beam indicated
by a synchronization signal block (SS block) that is sent by using
the beam. The SS block includes at least a primary synchronization
signal (PSS), and/or a secondary synchronization signal (SSS),
and/or a broadcast channel (PBCH).
[0074] It should be noted that descriptions are provided in the
following method embodiments by using an example in which the first
network device is a source base station and the second network
device is a target base station.
[0075] FIG. 2 is a flowchart of a communication method according to
Embodiment 1 of this application. As shown in FIG. 2, the method in
this embodiment may include the following steps.
[0076] S101. A target base station sends identification information
of N beams of a target cell and random access channel (RACH)
configurations of M beams in the N beams to a source base
station.
[0077] In this embodiment, the target base station performs
admission control, to allow a terminal to be handed over from a
serving cell to the target cell; and then the target base station
sends the identification information of the N beams of the target
cell and the RACH configurations of the M beams in the N beams to
the source base station. The RACH configuration may be
corresponding to an SS block, or may be corresponding to a CSI-RS.
N and M are positive integers. Further, the target base station may
alternatively send a cell identifier of the target cell to the
source base station.
[0078] Optionally, before the target base station sends the
information described in step S101 to the source base station, the
target base station may receive a handover request message sent by
the source base station. This is not limited in this
embodiment.
[0079] The identification information of the N beams and the RACH
configurations of the M beams may be included in a same message or
different messages sent by the target base station to the source
base station. Alternatively, the target base station may send the
identification information of the N beams and the RACH
configurations of the M beams to the source base station at a same
time point or different time points.
[0080] Optionally, the identification information of the N beams
and the RACH configurations of the M beams may be included in a
handover request acknowledgement message sent by the target base
station to the source base station.
[0081] S102. The source base station sends the identification
information of the N beams of the target cell and the RACH
configurations of the M beams in the N beams to a terminal.
[0082] In this embodiment, after receiving the identification
information of the N beams and the RACH configurations of the M
beams in the N beams that are sent by the target base station, the
source base station sends the identification information of the N
beams and the RACH configurations of the M beams in the N beams to
the terminal.
[0083] The identification information of the N beams and the RACH
configurations of the M beams may be included in a same message or
different messages sent by the source base station to the terminal.
Alternatively, the source base station may send the identification
information of the N beams and the RACH configurations of the M
beams to the terminal at a same time point or different time
points.
[0084] Optionally, the identification information of the N beams
and the RACH configurations of the M beams in the N beams may be
included in a handover message sent by the source base station to
the terminal. The handover message may be a radio resource control
(RRC) connection reconfiguration message that carries a mobility
control information element or another message such as another RRC
message different from the RRC connection reconfiguration message,
layer-1 signaling, or layer-2 signaling.
[0085] S103. The terminal determines a beam for accessing based on
at least signal quality or signal strength of L beams in the N
beams, the identification information of the N beams, and the RACH
configurations of the M beams.
[0086] In this embodiment, the terminal determines the beam for
accessing based on the signal quality or signal strength of the L
beams, the identification information of the N beams, and the RACH
configurations of the M beams. After determining the beam for
accessing, the terminal uses the beam to access the target cell to
which the beam belongs.
[0087] It can be understood that the terminal measures at least one
found beam, to obtain signal quality or signal strength of the
beam. The found beam is not limited to the N beams of the target
cell. In other words, a beam of a cell other than the target cell
may also be found. In addition, there is no limitation that each of
the N beams needs to be measured.
[0088] Optionally, in one case, L herein may alternatively be
considered as a quantity of beams whose signal quality or signal
strength is detected.
[0089] Herein, the M beams and the L beams may have an intersection
or may have no intersection. This is not limited in this embodiment
of this application.
[0090] Signal quality of a beam may be first signal received
quality of the beam. Signal strength of a beam may be a first
signal received power of the beam. A first signal includes a
synchronization signal and/or a reference signal.
[0091] In this embodiment, the source base station sends the
identification information of the N beams and the RACH
configurations of the M beams in the N beams to the terminal, and
then the terminal determines the beam for accessing based on the
signal quality or signal strength of the L beams in the N beams,
the identification information of the N beams, and the RACH
configurations of the M beams. Therefore, this embodiment provides
a proper beam for accessing determining solution. Further, the beam
for accessing in this embodiment is determined by the terminal
based on the signal quality or signal strength of the L beams in
the N beams and the received RACH configurations of the M beams.
Therefore, the beam for accessing determined in this manner can
increase a success rate of accessing a cell by the terminal,
increasing a handover success rate.
[0092] The following describes, by using signal strength of a beam
as an example, how to determine a beam for accessing. A solution of
the signal quality is similar to the solution of the signal
strength, and details are not described in the embodiments.
[0093] FIG. 3 is a flowchart of a communication method according to
Embodiment 2 of this application. As shown in FIG. 3, the method in
this embodiment may include the following steps.
[0094] S201. A terminal sends a measurement report to a source base
station.
[0095] Optionally, before sending the measurement report to the
source base station, the terminal receives measurement
configuration information sent by the source base station, and
performs measurement for a serving cell and a neighboring cell
based on the configuration information.
[0096] In a possible implementation, the configuration information
is used to configure the terminal to measure beams of the serving
cell and the neighboring cell. The configuration information
includes but is not limited to a beam quantity K and a beam signal
strength threshold that is X for short. The terminal determines
signal strength of the serving cell and signal strength of the
neighboring cell based on signal strength of K beams whose signal
strength is greater than or equal to X. When the determined signal
strength of the serving cell and the determined signal strength of
the neighboring cell meet a corresponding measurement event
determining condition, for example, a determining condition for an
event A3, an event A4, an event A5, or another measurement event in
LTE, the terminal sends the measurement report. The measurement
report includes signal strength of at least one neighboring cell,
and/or signal strength of K beams of each neighboring cell,
identification information of the serving cell, and identification
information of the at least one neighboring cell. The
identification information of the serving cell and the
identification information of the at least one neighboring cell
include a cell ID or a cell index. Optionally, the measurement
report may alternatively include identification information of K
beams used to generate the signal strength of the neighboring cell
or signal strength of K beams used to generate the signal strength
of the neighboring cell.
[0097] It can be understood that the neighboring cell includes the
target cell in the embodiment shown in FIG. 2. The configuration
information may alternatively not carry the beam quantity or beam
signal strength threshold information. In this case, the terminal
measures signal strength of a cell.
[0098] Optionally, an SS block and a CSI-RS are reference signals
and are transmitted on a beam. The measurement configuration
information is specifically used to configure the terminal to
measure the SS block and/or the CSI-RS transmitted on the beam.
Correspondingly, signal strength of the beam includes signal
strength of the SS block on the beam and/or signal strength of the
CSI-RS on the beam. A quantity of beams whose signal strength is
obtained by measuring the SS block may be the same as or different
from a quantity of beams whose signal strength is obtained by
measuring the CSI-RS. Correspondingly, a beam signal strength
threshold corresponding to the measurement configuration
information may include an SS block beam signal strength threshold
and/or a CSI-RS beam signal strength threshold. In other words, X
includes X1 and X2, where X1 is corresponding to the SS block beam
signal strength threshold, X2 is corresponding to the CSI-RS beam
signal strength threshold, and X1 may or may not be equal to
X2.
[0099] Identification information of a beam in this embodiment may
be identification information of an SS block transmitted on the
beam and/or identification information of a CSI-RS transmitted on
the beam.
[0100] The SS block is transmitted on a wide beam. The beam may be
identified by using the identification information of the SS block.
For example, the identification information of the SS block may be
a time index indication (implicitly or explicitly) carried on a
PBCH in the SS block.
[0101] The CSI-RS is transmitted on a narrow beam. The beam may be
identified by using the identification information of the CSI-RS.
For example, the identification information of the CSI-RS may be an
identifier of a CSI-RS configuration. The CSI-RS configuration
includes at least a resource configuration. The CSI-RS
configuration may further include an antenna port used to send the
CSI-RS, and the like.
[0102] Optionally, the measurement report may include information
about at least one beam (the information about the beam herein may
be signal strength of the beam and/or identification information of
the beam) of the neighboring cell. The information about the at
least one beam may be included in the measurement report in a form
of a list. For example, beam identifiers of beams of each
neighboring cell are arranged based on signal strength. The
information about the at least one beam may be used by a target
base station to determine beams (that is, M beams) configured with
RACH configurations.
[0103] The terminal may determine report information about which
beams of the neighboring cell in the measurement report, for
example, in the following three manners. This is not limited in
this embodiment.
[0104] In one manner, if a CSI-RS is measured, because a CSI-RS
resource is configured by the source base station for the terminal
in a measurement configuration message, if W CSI-RS resources are
configured in the measurement configuration message, the terminal
reports information about beams corresponding to the W CSI-RS
resources, that is, information about a beam corresponding to each
of the W CSI-RS resources.
[0105] In another manner, a measurement configuration message
received by the terminal includes a threshold. The threshold Q is
not equal to X. The threshold is used by the terminal to determine
whether information about a beam needs to be reported. That is, if
signal strength, measured by the terminal, of a beam of the
neighboring cell is higher than (not lower than) the threshold, the
terminal reports the information about the beam in the measurement
report.
[0106] In another manner, optionally, the terminal reports
information about a maximum of P beams based on a value P, or may
report, based on the threshold Q, information about a maximum of P
beams whose signal quality or signal strength is higher than Q. The
value P may be a preset maximum value P, or may be included in the
measurement configuration message sent by the source base station
to the terminal.
[0107] It can be understood that the measurement report reporting
manner and content of the measurement configuration information may
be independent of this embodiment of this application, that is, may
be applied to another solution different from this embodiment of
this application.
[0108] S202. The source base station sends a handover request
message to a target base station.
[0109] In this embodiment, the source base station receives the
measurement report sent by the terminal, and performs handover
decision based on the measurement report. The source base station
may send the handover request message to a target base station to
which a target cell belongs, where a neighboring cell with highest
signal strength in a plurality of reported neighboring cells may be
used as the target cell, and the handover request message may
include an identifier of the target cell.
[0110] Optionally, the handover request message may further include
information about at least one beam of the target cell (including
signal strength of the beam and/or identification information of
the beam).
[0111] Optionally, the source base station may send the handover
request message to each of the plurality of neighboring cells based
on signal strength of the plurality of neighboring cells in the
measurement report. This can ensure that when the target base
station does not allow the terminal to be handed over to the target
cell, a base station to which another neighboring cell belongs can
allow, based on the handover request message, the terminal to be
handed over to the another neighboring cell.
[0112] The source base station may alternatively send the handover
request message to the target base station based on, but not
limited to, the measurement report sent by the terminal. For
example, the source base station alternatively sends the handover
request message to the target base station based on a current
network status, or the like.
[0113] It can be understood that the handover request message is
used as an example for description. Corresponding handover
preparation interaction may alternatively be completed through
another message, and such a type of message may be referred to as a
first message.
[0114] S203. The target base station sends a handover request
acknowledgement message to the source base station.
[0115] In this embodiment, the target base station replies to the
source base station with the handover request acknowledgement
message after performing admission control based on the handover
request message. The handover request acknowledgement message
includes identification information of N beams of the target cell
and RACH configurations of M beams in the N beams.
[0116] It can be understood that the handover request
acknowledgement message is used as an example for description.
Corresponding handover preparation interaction may alternatively be
completed through another message, and such a type of message may
be referred to as a second message. The second message is an
acknowledgement message for the first message.
[0117] S204. The source base station sends a handover message to
the terminal.
[0118] In this embodiment, after receiving the handover request
acknowledgement message, the source base station sends the handover
message to the terminal. The handover message includes the
identification information of the N beams of the target cell and
the RACH configurations of the M beams.
[0119] It can be understood that the handover message is used as an
example for description. A corresponding handover indication may
alternatively be completed through another message, and such a type
of message may be referred to as a third message.
[0120] Optionally, the identification information of the N beams
may be sent in a form of a list. Certainly, the identification
information of the N beams may alternatively be sent in another
form. This is not limited in this embodiment.
[0121] It can be understood that the handover message may further
carry corresponding priority information, and the priority
information may be notified in different manners, and examples are
as follows.
[0122] In a first manner, the identification information of the N
beams is sent in the form of a list. The list has a priority order,
that is, a beam order and a beam priority are bound in the list.
For example, for identification information of the first beam in
the list, the beam has a highest priority, and beams are arranged
sequentially based on a priority order. Identification information
of two beams is used as an example. If a list is {identification
information of a beam 2, identification information of a beam 1}, a
priority of the beam 2 is higher than a priority of the beam 1.
[0123] In a second manner, the identification information of the N
beams is sent in a form of a list. The list further includes
priority information corresponding to a beam. The priority
information is used to indicate a beam priority. Two beams are used
as an example. The two beams are sent in a form of a list. The list
does not have a priority order, but the list includes priority
information of the beams. If the list is {identification
information of a beam 1 and priority information=2, identification
information of a beam 2 and priority information=1}, it indicates
that a priority of the beam 2 is higher than a priority of the beam
1.
[0124] S205. The terminal determines abeam for accessing based on
signal strength of L beams in N beams, strength threshold
information, identification information of the N beams, and RACH
configurations of the M beams.
[0125] The strength threshold information may be pre-specified, or
may be received by the terminal.
[0126] It can be understood that if the beam for accessing the
target cell is determined based on signal quality, corresponding
quality threshold information is used.
[0127] The terminal may receive the strength threshold information
sent by the source base station. For example, the strength
threshold information is included in the handover message sent by
the source base station to the terminal. In a manner, the strength
threshold information is included in the handover message.
Alternatively, optionally, minimum system information (minimum SI)
is carried in the handover message, and the strength threshold
information is included in the minimum system information (minimum
SI) in the handover message. The strength threshold information may
be determined by the source base station, or the strength threshold
information may be sent by the target base station and received by
the source base station. For example, the strength threshold
information is included in the handover request acknowledgement
message sent by the target base station to the source base
station.
[0128] The terminal may receive the strength threshold information
sent by the target base station. For example, the strength
threshold information is included in system information (SI) that
is broadcast by the target base station by using the target cell.
The SI may include minimum system information (minimum SI) and
other system information (other SI) different from the minimum
system information. The strength threshold information may be
included in the minimum SI in the SI, or may be included in the
OSI.
[0129] The strength threshold information includes a first beam
signal strength threshold and/or strength threshold indication
information, the strength threshold indication information is used
to indicate a relationship between the first beam signal strength
threshold and a second beam signal strength threshold, and the
second beam signal strength threshold is a beam signal strength
threshold carried in the measurement configuration message, namely,
X mentioned above.
[0130] In this embodiment, after receiving the handover message,
the terminal determines the first beam signal strength threshold
based on the strength threshold information; and compares the
signal strength of the L beams in the N beams with the first beam
signal strength threshold based on the identification information
of the N beams, and determines, based on the RACH configurations of
the M beams in the N beams, the beam for accessing the target
cell.
[0131] The following provides descriptions by using a first beam
signal strength threshold Y as an example.
[0132] The strength threshold indication information may indicate a
relationship between X and Y, for example, indicating whether X is
equal to Y. The strength threshold indication information may be a
binary bit value. For example, "o" indicates that X is not equal to
Y, and "1" indicates that X is equal to Y; vice versa.
Alternatively, the strength threshold indication information is a
Boolean value. `TRUE` indicates that X is equal to Y, and `FALSE`
indicates that X is not equal to Y; vice versa. Alternatively, the
strength threshold indication information is an information
element. When the information element is carried, it indicates that
X is not equal to Y, and when the information element is not
carried, it indicates that X is equal to Y; vice versa.
[0133] If X is equal to Y, optionally, the strength threshold
information may not carry the value Y, and after parsing out that
"X is equal to Y" indicated in the strength threshold indication
information, the terminal determines, based on the value X, the
beam for accessing the target cell. Optionally, if X is not equal
to Y, the strength threshold information carries the value Y.
Optionally, the strength threshold information may not carry the
strength threshold indication information.
[0134] Optionally, when the identification information of the N
beams include identification information of an SS block transmitted
on a beam and/or identification information of a CSI-RS transmitted
on a beam, the strength threshold indication information may be SS
block strength threshold indication information and CSI-RS strength
threshold indication information. The first beam signal strength
threshold (Y) includes a first SS block beam signal strength
threshold (Y1) and a first CSI-RS beam signal strength threshold
(Y2).
[0135] Optionally, the strength threshold information further
includes first indication information. The first indication
information is used to indicate a relationship between Y1 and Y2,
for example, whether Y1 is equal to Y2. The first indication
information may be a binary bit value. For example, "0" indicates
that Y1 is not equal to Y2, and "1" indicates that Y1 is equal to
Y2; vice versa. Alternatively, the first indication information is
a Boolean value. `TRUE` indicates that Y1 is equal to Y2, and
`FALSE` indicates that Y1 is not equal to Y2; vice versa.
Alternatively, the first indication information is an information
element. When the information element is carried, it indicates that
Y1 is not equal to Y2, and when the information element is not
carried, it indicates that Y1 is equal to Y2; vice versa.
[0136] If the threshold Y1 is equal to the threshold Y2,
optionally, the strength threshold information may carry a
threshold, to be specific, Y, where both Y1 and Y2 are Y. Because
the strength threshold information carries the threshold Y, after
parsing out that "Y1 is equal to Y2" indicated by the first
indication information, the terminal uses the value Y
(corresponding to both signal strength of the SS block transmitted
on a beam and signal strength of a CSI-RS transmitted on a beam) to
determine the beam for accessing the target cell. If Y1 is not
equal to Y2, the strength threshold information carries two values,
that is, Y1 and Y2, and the terminal uses Y1 and Y2 to determine
the beam for accessing the target cell.
[0137] Based on the description of the strength threshold
information, S205 may be specifically: The terminal can determine,
based on the received RACH configurations of the M beams in the N
beams, that a RACH configuration is configured for each of the M
beams (that is, a RACH configuration corresponding to each beam is
configured for the beam); and the terminal can obtain the signal
strength of the L beams in the N beams, compare the signal strength
of the L beams with the first beam signal strength threshold, and
determine the beam for accessing on this.
[0138] In a first feasible implementation, the N beams include a
beam that meets the following two conditions: A RACH configuration
is configured for the beam, and signal strength of the beam is
greater than or equal to the first beam signal strength
threshold.
[0139] The terminal determines at least one beam whose signal
strength is greater than or equal to the first beam signal strength
threshold from the M beams as the beam for accessing the target
cell. That is, if determining that a RACH configuration is
configured for a beam and signal strength of the beam is greater
than or equal to the first beam signal strength threshold, the
terminal determines the beam as the beam for accessing the target
cell. In this implementation, the determined beam for accessing the
target cell belongs to the N beams, and belongs to the M beams.
[0140] Optionally, the identification information of the N beams
includes identification information of an SS block and/or
identification information of a CSI-RS. Therefore, when the N beams
include both a beam identified by the identification information of
the SS block and a beam identified by the identification
information of the CSI-RS, a priority of the beam identified by the
identification information of the CSI-RS is higher than that of the
beam identified by the identification information of the SS block,
and the terminal preferentially determines, as the beam the target
cell, a beam configured with a RACH configuration, whose signal
strength is greater than or equal to the first beam signal strength
threshold, and that is identified by the identification information
of the CSI-RS. If no beam identified by identification information
of CSI meets the following conditions: The RACH configuration of
the beam belongs to the RACH configurations of the M beams and
signal strength is greater than or equal to the first beam signal
strength threshold; the terminal determines a beam configured with
a RACH configuration, whose signal strength is greater than or
equal to the first beam signal strength threshold, and that is
identified by the identification information of the SS block as the
beam for accessing the target cell.
[0141] It can be understood that if a plurality of beams that meet
the foregoing two conditions are determined in the foregoing
manners, the terminal may determine the first found beam that meets
the foregoing conditions as the beam for accessing the target cell;
or the terminal may randomly select, from the beams that meet the
foregoing conditions, the beam for accessing the target cell; or
the terminal may select a beam with highest signal strength from
the beams that meet the foregoing conditions, as the beam for
accessing the target cell; or the terminal may select a beam with a
highest priority from the beams that meet the foregoing conditions,
as the beam for accessing the target cell. For a beam priority
order, refer to the foregoing related descriptions.
[0142] Optionally, a priority order of the beam identified by the
identification information of the CSI-RS and the beam identified by
the identification information of the SS block may be predefined,
or may be configured by a network device. For example, the priority
order is indicated through the handover message.
[0143] A RACH configuration of each of the M beams includes a
preamble index and a time-frequency resource configuration. The
RACH configuration may be considered as a contention free random
access (CFRA) configuration. When the beam that is for accessing
the target cell and that is determined by the terminal belongs to
the M beams, the terminal initiates a random access process to the
target cell based on the RACH configuration of the beam.
[0144] In this implementation, the beam that is for accessing the
target cell and that is determined by the terminal has the RACH
configuration and high signal strength. In this way, a success rate
of accessing the target cell by the terminal is higher.
[0145] In a second feasible implementation, when signal strength of
each of the M beams is less than the first beam signal strength
threshold, the beam for accessing the target cell is determined
from the M beams. For example, the terminal searches the N beams
for the signal strength of M beams, and when the signal strength of
each of the M beams is less than the first beam signal strength
threshold, determines the beam for accessing the target cell from
the M beams. The determined beam for accessing the target cell in
this embodiment belongs to the M beams.
[0146] When M is greater than 1, the terminal may determine the
first found beam in the M beams as the beam for accessing the
target cell, the terminal may randomly select, from the M beams,
the beam for accessing the target cell, the terminal may select a
beam with highest signal strength from the M beams as the beam for
accessing the target cell, or the terminal may select a beam with a
highest priority from the M beams as the beam for accessing the
target cell. For a beam priority order, refer to the foregoing
related descriptions.
[0147] Optionally, the identification information of the N beams
includes identification information of an SS block and/or
identification information of a CSI-RS. Therefore, when the N beams
include both a beam identified by the identification information of
the SS block and a beam identified by the identification
information of the CSI-RS, a priority of the beam identified by the
identification information of the CSI-RS is higher than that of the
beam identified by the identification information of the SS block,
and the terminal preferentially determines the beam for accessing
the target cell from the beam identified by the identification
information of the CSI-RS in the M beams. If the M beams do not
include a beam identified by identification information of CSI, the
terminal determines the beam for accessing the target cell from the
beam identified by the identification information of the SS block
in the M beams.
[0148] It can be understood that the manner of determining the beam
for accessing the target cell from the beam identified by the
identification information of the CSI-RS or determining the beam
for accessing the target cell from the beam identified by the
identification information of the SS block in the M beams is
similar to the manner of determining the beam for accessing the
target cell from the M beams in the second feasible
implementation.
[0149] In this implementation, the beam that is for accessing the
target cell and that is determined by the terminal has the RACH
configuration. In this way, a success rate of accessing the target
cell by the terminal is high.
[0150] In a third feasible implementation, signal strength of each
of the M beams is less than the first beam signal strength
threshold, and the L beams include a beam whose signal strength is
greater than or equal to the first beam signal strength
threshold.
[0151] The terminal determines, based on the identifiers of the N
beams, the signal strength of the L beams, and the strength
threshold information, the beam whose signal strength is greater
than or equal to the first beam signal strength threshold as the
beam for accessing the target cell. In this case, the beam whose
signal strength is greater than or equal to the first beam signal
strength threshold may be understood as one of the L beams. That
is, the terminal searches the N beams for the signal strength of
the L beams, and when the signal strength of each of the M beams is
less than the first beam signal strength threshold, the terminal
determines the beam for accessing the target cell from the L beams
based on that a signal strength threshold of the beam for accessing
the target cell is greater than or equal to the first beam signal
strength threshold. If the L beams include a plurality of beams
whose signal strength is greater than or equal to the first beam
signal strength threshold, the terminal may determine the first
found beam whose signal strength is greater than or equal to the
first beam signal strength threshold as the beam for accessing the
target cell. Alternatively, the terminal may randomly select, from
the beams whose signal strength is greater than or equal to the
first beam signal strength threshold, the beam for accessing the
target cell, or the terminal may select a beam with highest signal
strength from the beams whose signal strength is greater than or
equal to the first beam signal strength threshold as the beam for
accessing the target cell, or the terminal may select a beam with a
highest priority from the beams whose signal strength is greater
than or equal to the first beam signal strength threshold as the
beam for accessing the target cell. For a beam priority order,
refer to the foregoing related descriptions.
[0152] Optionally, the identification information of the N beams
includes identification information of an SS block and/or
identification information of a CSI-RS. Therefore, when the N beams
include both a beam identified by the identification information of
the SS block and a beam identified by the identification
information of the CSI-RS, a priority of the beam identified by the
identification information of the CSI-RS is higher than that of the
beam identified by the identification information of the SS block,
and the terminal preferentially determines, as the beam for
accessing the target cell, a beam whose signal strength is greater
than or equal to the first beam signal strength threshold and that
is identified by the identification information of the CSI-RS. If
the beam identified by identification information of CSI does not
include a beam whose signal strength is greater than or equal to
the first beam signal strength threshold, the terminal determines,
as the beam for accessing the target cell, a beam whose signal
strength is greater than or equal to the first beam signal strength
threshold and that is identified by the identification information
of the SS block.
[0153] It can be understood that when there are a plurality of
determined beams whose signal strength is greater than or equal to
the first beam signal strength threshold and that is identified by
the identification information of the CSI-RS or the identification
information of the SS block, a processing manner similar to the
processing manner used in the third feasible implementation when
the L beams include a plurality of beams whose signal strength is
greater than or equal to the first beam signal strength threshold,
and details are not described herein again.
[0154] Optionally, when the beam that is for accessing the target
cell and that is determined by the terminal does not belong to the
M beams, the terminal may listen to and parse system information of
the target cell, and initiate random access to the target cell
based on a common RACH configuration in the system information.
[0155] In this implementation, the terminal determines that the
beam for accessing the target cell has high signal strength. In
this way, a success rate of accessing the target cell by the
terminal is high.
[0156] In a fourth feasible implementation, signal strength of each
of the M beams is less than the first beam signal strength
threshold, and the L beams do not include a beam whose signal
strength is greater than or equal to the first beam signal strength
threshold.
[0157] The terminal determines, from the L beams based on the
identifiers of the N beams and the signal strength of the L beams,
a beam with highest signal strength as the beam for accessing the
target cell; or the terminal may determine the first found beam in
the L beams as the beam for accessing the target cell; or the
terminal may randomly select, from the L beams, the beam the target
cell; or the terminal may select a beam with a highest priority
from the L beams as the beam for accessing the target cell, where
for a beam priority order, refer to the foregoing related
descriptions.
[0158] The determined beam for accessing the target cell in this
embodiment belongs to the L beams, but the beam that is for
accessing the target cell and that is determined in this case may
or may not belong to the M beams.
[0159] Optionally, the identification information of the N beams
includes identification information of an SS block and/or
identification information of a CSI-RS. Therefore, when the N beams
include both a beam identified by the identification information of
the SS block and a beam identified by the identification
information of the CSI-RS, a priority of the beam identified by the
identification information of the CSI-RS is higher than that of the
beam identified by the identification information of the SS block,
and the terminal preferentially determines, as the beam for
accessing the target cell, a beam with highest signal strength from
the beam identified by the identification information of the CSI-RS
in the L beams. If the L beams do not include a beam identified by
identification information of CSI, the terminal determines, as the
beam the target cell, a beam with highest signal strength from the
beam identified by the identification information of the SS block
in the L beams. It can be understood that the manner of determining
the beam the target cell from the beam identified by the
identification information of the CSI-RS or from the beam
identified by the identification information of the SS block may
alternatively be determining the first found beam as the beam for
accessing the target cell, or randomly selecting a beam, or
selecting a beam with a highest priority. This is not limited in
this embodiment of this application.
[0160] In this implementation, the terminal determines, in a
relatively flexible manner, the beam for accessing the target
cell.
[0161] It can be understood that in the foregoing feasible
implementations, descriptions are provided by using a case in which
M is greater than or equal to 1 as an example. In a possible case,
M may alternatively be equal to 0, indicating that the target base
station provides no RACH configuration for the beam of the target
cell. In this case, the beam for accessing the target cell may be
determined in the following manner: The terminal finds L beams in
the N beams, and the terminal may determine the beam for accessing
the target cell from the L beams. For example, the terminal
determines a beam with highest signal strength from the L beams as
the beam for accessing the target cell, or the terminal determines
the first found beam in the L beams as the beam for accessing the
target cell, or the terminal determines a beam with a highest
priority from the L beams as the beam the target cell, or the
terminal randomly determines, from the L beams, the beam the target
cell. It can be understood that when M=0, the manner of determining
the beam for accessing the target cell may also be applicable to a
scenario in which none of the M beams is found.
[0162] In another possible implementation, when none of the M beams
is found, or M is equal to 0, or none of the N beams is found, or
signal strength of each of the L or M beams is less than the first
beam signal strength threshold, it indicates that when the target
base station provides no RACH configuration for the beam of the
target cell, the beam for accessing may alternatively be determined
in one of the following manners.
[0163] (1) The terminal determines a beam with highest signal
strength from a found beam of the target cell as the beam for
accessing the target cell, or the terminal determines the first
found beam of the target cell as the beam for accessing the target
cell, or the terminal determines a beam with a highest priority
from a found beam of the target cell as the beam for accessing the
target cell, or the terminal randomly determines, from a beam of
the target cell, the beam for accessing the target cell. According
to this manner, the terminal preferentially accesses the target
cell, to avoid an access failure as much as possible.
[0164] (2) The terminal determines a beam with highest signal
strength from a found beam as the beam for accessing.
Alternatively, the terminal determines the first found beam as the
beam for accessing; in this case, the beam may belong to the target
cell. Alternatively, the terminal determines a beam with a highest
priority from a found beam as a beam for accessing a neighboring
cell. Alternatively, the terminal randomly determines the beam for
accessing, and the beam may belong to the target cell. The beam for
accessing may belong to the target cell, or the beam for accessing
may belong to a neighboring cell other than the target cell.
[0165] (3) The terminal initiates an RRC connection
re-establishment process, and optionally, the terminal performs the
RRC connection re-establishment process in a current serving
cell.
[0166] Based on the foregoing embodiment of this application,
optionally, the terminal initiates an RRC connection
re-establishment process if the terminal determines the beam in the
foregoing manner and initiates a random access process, but the
random access process fails, for example, a quantity of times of
sending a preamble index by the terminal reaches a maximum quantity
of sending times, but the terminal does not receive a random access
response (RAR) message returned by the base station. Optionally,
the terminal performs the RRC connection re-establishment process
in the current serving cell.
[0167] The foregoing embodiment of this application provides a
plurality of beam for accessing determining manners, so that the
terminal flexibly selects a beam for accessing.
[0168] FIG. 4 is a flowchart of a communication method according to
Embodiment 3 of this application. As shown in FIG. 4, the method in
this embodiment may include the following steps.
[0169] S301. A terminal sends a measurement report to a source base
station, where the measurement report includes serving beam change
information of the terminal within a predetermined time period.
[0170] For the measurement report in this embodiment, refer to
related descriptions in the embodiment shown in FIG. 3. In
addition, the measurement report in this embodiment further
includes the serving beam change information of the terminal within
the predetermined time period. The serving beam change information
is information, for example, a quantity of serving beam changes of
the terminal within the predetermined time period or duration for
which the terminal stays in each serving beam.
[0171] Optionally, the beam change information is not limited to
being included in the measurement report, or may be included in a
new RRC message, layer-1 signaling, or layer-2 signaling sent by
the terminal to the source base station.
[0172] S302. The source base station sends a handover request
message to a target base station, where the handover request
message includes the serving beam change information.
[0173] For the handover request message in this embodiment, refer
to related descriptions in the embodiment shown in FIG. 3. In
addition, the handover request message in this embodiment further
includes the serving beam change information.
[0174] S303. The target base station determines a validity period
of RACH configurations of M beams based on the serving beam change
information.
[0175] In this embodiment, the target base station may
substantially determine a movement status of the terminal based on
the serving beam change information, and determine the validity
period of the RACH configurations of the M beams based on the
movement status of the terminal. If it is determined, based on the
serving beam change information, that the terminal changes a
serving beam frequently, the validity period of the RACH
configurations that are of the M beams and that are to be allocated
by the target base station is relatively short, otherwise, the
validity period of the RACH configurations that are of the M beams
and that are to be allocated by the target base station is
relatively long.
[0176] In a replaceable solution of S302 and S303, the source base
station determines the validity period based on the serving beam
change information; and then the source base station sends the
handover request message to the target base station, where the
handover request message includes the validity period. The target
base station determines, based on the handover request message,
that the validity period in the handover request message is the
validity period of the RACH configurations of the M beams.
[0177] It can be understood that after the validity period of the
RACH configurations expires, the target base station releases the
RACH configurations of the M beams, thereby avoiding wasting
resources for a long time.
[0178] All of steps S301 to S303 may alternatively be independent
of subsequent steps and applied to another scenario or solution.
S301 to S303 in this embodiment are applied to, but not limited to,
the scenario or solution in this embodiment.
[0179] S304. The target base station sends a handover request
acknowledgement message to the source base station.
[0180] In this embodiment, the handover request acknowledgement
message includes identification information of N beams and the RACH
configurations of the M beams. For the handover request message in
this embodiment, refer to related descriptions in the embodiment
shown in FIG. 3.
[0181] There is no particular order for performing steps S303 and
S304.
[0182] S305. The source base station sends a handover message to
the terminal, where the handover message includes identification
information of N beams of a target cell and the RACH configurations
of the M beams.
[0183] S306. The terminal determines a beam for accessing based on
at least signal strength of L beams in the N beams, the
identification information of the N beams, and the RACH
configurations of the M beams.
[0184] In this embodiment, for S305 and S306, refer to related
descriptions in the foregoing embodiments. Details are not
described herein again.
[0185] S307. The terminal sends, based on the beam for accessing, a
preamble index to a base station corresponding to the beam.
[0186] Herein, the base station corresponding to the beam may be
the target base station, or may be another base station. FIG. 4
shows an example in which the base station corresponding to the
beam is the target base station, but this is not limited in this
embodiment.
[0187] S308. The base station corresponding to the beam sends a
random access response (RAR) message to the terminal.
[0188] If the terminal determines that a beam for accessing the
target cell belongs to the M beams, it indicates that a RACH
configuration is configured for the beam for accessing the target
cell. In this case, the terminal sends a preamble index to the
target base station by using the RACH configuration. The target
base station determines, based on the preamble index sent by the
terminal and/or a time-frequency resource used for sending the
preamble index, a beam selected for random access performed by the
terminal to the target cell, the target base station sends an RAR
message to the terminal based on the beam, and the target base
station releases RACH configurations of other beams in the M
beams.
[0189] If the terminal determines that a beam for accessing the
target cell does not belong to the M beams, it indicates that no
RACH configuration is configured for the beam for accessing the
target cell. In this case, the terminal sends a randomly selected
preamble index to the target base station on a common random access
channel time-frequency resource.
[0190] S309. The terminal sends an RRC connection reconfiguration
complete message to the base station corresponding to the beam.
[0191] After receiving the RAR message, the terminal sends the RRC
connection reconfiguration complete message to the base station
corresponding to the beam.
[0192] In this embodiment, according to the foregoing solution, the
terminal determines the beam for accessing the target cell, and a
success rate of accessing the target cell by the terminal can be
improved based on the beam, increasing a handover success rate. In
addition, the terminal further reports the serving beam change
information of the terminal, so that the target base station
determines the validity period of the RACH configurations of the M
beams, and after the validity period expires, releases the RACH
configurations of the M beams, avoiding occupying resources for a
long time and increasing resource utilization.
[0193] It can be understood that in the foregoing embodiments, the
methods or steps implemented by the terminal may alternatively be
implemented by a chip inside the terminal. The methods or steps
implemented by a base station such as the source base station may
alternatively be implemented by a chip inside the base station.
[0194] An embodiment of this application provides a communications
apparatus. The communications apparatus may be a terminal, or may
be a chip inside a terminal. As shown in FIG. 5, the communications
apparatus in this embodiment may include a receiving module 11 and
a processing module 12.
[0195] The receiving module 11 is configured to receive
identification information of N beams of a target cell and random
access channel configurations of M beams in the N beams, where N
and M are positive integers.
[0196] The processing module 12 is configured to determine a beam
for accessing based on signal quality or signal strength of L beams
in the N beams, the identification information of the N beams, and
the random access channel configurations of the M beams, where L is
a nonnegative integer.
[0197] Optionally, the processing module 12 is specifically
configured to determine the beam for accessing based on the signal
strength of the L beams in the N beams, strength threshold
information, the identification information of the N beams, and the
random access channel configurations of the M beams.
[0198] Optionally, the receiving module 11 is further configured to
receive the strength threshold information.
[0199] Optionally, the strength threshold information includes a
first beam signal strength threshold or strength threshold
indication information, the strength threshold indication
information is used to indicate a relationship between the first
beam signal strength threshold and a second beam signal strength
threshold, and the second beam signal strength threshold is a beam
signal strength threshold carried in measurement configuration
information.
[0200] Optionally, the processing module 12 is specifically
configured to determine, based on the signal strength of the L
beams in the N beams, the strength threshold information, the
identification information of the N beams, and the random access
channel configurations of the M beams, a beam whose signal strength
is greater than or equal to the first beam signal strength
threshold from the M beams as the beam for accessing the target
cell.
[0201] Optionally, the processing module 12 is specifically
configured to: when signal strength of each of the M beams is less
than the first beam signal strength threshold, determine, from the
M beams based on the identification information of the N beams and
the random access channel configurations of the M beams, the beam
for accessing the target cell.
[0202] Optionally, the processing module 12 is specifically
configured to: when signal strength of each of the M beams is less
than the first beam signal strength threshold, determine, based on
the identifiers of the N beams, the signal strength of the L beams,
and the strength threshold information, a beam whose signal
strength is greater than or equal to the first beam signal strength
threshold from the L beams as the beam for accessing the target
cell.
[0203] Optionally, the processing module 12 is specifically
configured to determine, based on the signal strength of the L
beams, the strength threshold information, the identification
information of the N beams, a priority order of the N beams, and
the random access channel configurations of the M beams, the beam
for accessing the target cell.
[0204] Optionally, the processing module 12 is specifically
configured to: when none of the M beams is found, determine, based
on the identification information of the N beams, a beam with
highest signal strength in the L beams as the beam for accessing
the target cell.
[0205] Optionally, the identification information of the N beams
includes synchronization signal block identification information
and/or channel state information-reference signal identification
information.
[0206] The processing module 12 is specifically configured to
determine the beam for accessing based on the signal strength of
the L beams in the N beams, the strength threshold information, the
identification information of the N beams, that a priority of a
beam whose identification information is the channel state
information-reference signal identification information is higher
than that of a beam whose identification information is the
synchronization signal block identification information, and the
random access channel configurations of the M beams.
[0207] Optionally, the processing module 12 is further configured
to: if none of the N beams is found, the signal strength of the L
beams or signal strength of the M beams is less than the first beam
signal strength threshold, or none of the M beams is found,
determine the first found beam as the beam for accessing, determine
a beam with highest signal strength as the beam for accessing,
randomly determine a found beam as the beam for accessing, or
determine a beam with a highest priority in found beams as the beam
for accessing.
[0208] Optionally, the random access channel configuration includes
a preamble index and a time-frequency resource configuration.
[0209] The communications apparatus described in this embodiment
may be configured to execute the technical solutions executed by
the terminal/the terminal chip in the foregoing method embodiments.
An implementation principle and a technical effect of the
communications apparatus are similar to those of the foregoing
method embodiments. For functions of the modules, refer to
corresponding descriptions in the method embodiments. Details are
not described herein.
[0210] FIG. 6 is a schematic structural diagram of a terminal
according to an embodiment of this application. As shown in FIG. 6,
the terminal in this embodiment may include a processor 21 and a
transceiver 22. The processor 21 is communicatively connected to
the transceiver 22.
[0211] In hardware implementation, the receiving module 11 may be
the transceiver 22 in this embodiment. Alternatively, the
transceiver 22 includes a transmitter and a receiver; in this case,
the receiving module 11 may be the receiver of the transceiver 22.
The processing module 12 may be embedded in or independent of the
processor 21 of the terminal in a form of hardware.
[0212] The transceiver 22 may include necessary radio frequency
communications devices such as a frequency mixer. The processor 21
may include at least one of a central processing unit (CPU), a
digital signal processor (DSP), a microcontroller unit (MCU), an
application-specific integrated circuit (ASIC), or a
field-programmable gate array (FPGA).
[0213] Optionally, the terminal in this embodiment may further
include a memory 23. The memory 23 is configured to store a program
instruction. The processor 21 is configured to invoke the program
instruction in the memory 23 to execute the foregoing
solutions.
[0214] The program instruction may be implemented in a form of a
software functional unit and can be sold or used as an independent
product. The memory 23 may be a computer readable storage medium in
any form. Based on such understanding, all or some of the technical
solutions of this application may be represented in a form of a
software product, and the software product includes several
instructions for instructing a computer device, which may be
specifically the processor 21, to perform all or some of the steps
of the terminal in the embodiments of this application. The
computer readable storage medium includes various media that can
store program code, such as a USB flash drive, a removable hard
disk, a read-only memory (ROM), a random access memory (RAM), a
magnetic disk, and a compact disc.
[0215] The terminal described in this embodiment may be configured
to execute the technical solutions executed by the terminal or the
chip inside the terminal in the foregoing method embodiments of
this application. An implementation principle and a technical
effect of the terminal are similar to those of the foregoing method
embodiments. For functions of the modules, refer to corresponding
descriptions in the method embodiments. Details are not described
herein.
[0216] An embodiment of this application provides a communications
apparatus. The communications apparatus may be a network device or
a chip inside a network device. As shown in FIG. 7, the
communications apparatus may include a receiving module 31 and a
sending module 32.
[0217] The receiving module 31 is configured to receive
identification information of N beams of a target cell and random
access channel configurations of M beams in the N beams that are
sent by a second network device, where N and M are positive
integers.
[0218] The sending module 32 is configured to send the
identification information of the N beams and the random access
channel configurations of the M beams to a terminal.
[0219] Optionally, the receiving module 31 is further configured to
receive serving beam change information of the terminal that is
within a predetermined time period and that is sent by the
terminal.
[0220] The sending module 32 is further configured to send the
serving beam change information to the second network device, where
the serving beam change information is used by the second network
device to determine a validity period of the random access channel
configurations of the M beams.
[0221] Optionally, the communications apparatus in this embodiment
further includes a processing module 33.
[0222] The receiving module 31 is further configured to receive
serving beam change information of the terminal that is within a
predetermined time period and that is sent by the terminal.
[0223] The processing module 33 is configured to determine a
validity period of the random access channel configurations of the
M beams based on the serving beam change information.
[0224] The sending module 32 is further configured to send the
validity period of the random access channel configurations of the
M beams to the second network device.
[0225] Optionally, the random access channel configuration includes
a preamble index and a time-frequency resource configuration.
[0226] Optionally, the sending module 32 is further configured to
send strength threshold information or quality threshold
information of a beam signal to the terminal through a handover
message.
[0227] The communications apparatus described in this embodiment
may be configured to execute the technical solutions executed by
the source base station or a chip inside the source base station in
the foregoing method embodiments. An implementation principle and a
technical effect of the communications apparatus are similar to
those of the foregoing method embodiments. For functions of the
modules, refer to corresponding descriptions in the method
embodiments. Details are not described herein.
[0228] FIG. 8 is a schematic structural diagram of a network device
according to an embodiment of this application. As shown in FIG. 8,
the network device in this embodiment may include a processor 41
and a transceiver 42. The processor 41 is communicatively connected
to the transceiver 42.
[0229] In hardware implementation, the receiving module 31 and the
sending module 32 may be the transceiver 42 in this embodiment.
Alternatively, the transceiver 42 includes a transmitter and a
receiver; in this case, the receiving module 31 may be the receiver
of the transceiver 42, and the sending module 32 may be the
transmitter of the transceiver 42. The processing module 33 may be
embedded in or independent of the processor 41 of the network
device in a form of hardware.
[0230] The transceiver 42 may include necessary radio frequency
communications devices such as a frequency mixer. The processor 41
may include at least one of a CPU, a DSP, an MCU, an ASIC, or an
FPGA.
[0231] Optionally, the network device in this embodiment may
further include a memory 43. The memory 43 is configured to store a
program instruction. The processor 41 is configured to invoke the
program instruction in the memory 43 to execute the foregoing
solutions.
[0232] The program instruction may be implemented in a form of a
software functional unit and can be sold or used as an independent
product. The memory 43 may be a computer readable storage medium in
any form. Based on such understanding, all or some of the technical
solutions of this application may be represented in a form of a
software product, and the software product includes several
instructions for instructing a computer device, which may be
specifically the processor 41, to perform all or some of the steps
of the network device in the embodiments of this application. The
computer readable storage medium includes various media that can
store program code, such as a USB flash drive, a removable hard
disk, a ROM, a RAM, a magnetic disk, and a compact disc.
[0233] The network device in this embodiment may be configured to
execute the technical solutions of the source base station in the
foregoing method embodiments of this application. An implementation
principle and a technical solution of the network device are
similar to those of the foregoing method embodiments, and details
are not described herein.
[0234] An embodiment of this application provides a communications
apparatus. The communications apparatus may be a network device or
a chip inside a network device. As shown in FIG. 9, the
communications apparatus may include a sending module 51.
[0235] The sending module 51 is configured to send identification
information of N beams of a target cell and random access channel
configurations of M beams in the N beams to a first network device,
where N and M are positive integers.
[0236] Optionally, the communications apparatus further includes a
receiving module 52 and a processing module 53.
[0237] In a feasible implementation, the receiving module 52 is
configured to receive serving beam change information of a terminal
that is within a predetermined time period and that is sent by the
first network device.
[0238] The processing module 53 is configured to: determine a
validity period of the random access channel configurations of the
M beams based on the serving beam change information; and after the
validity period expires, release the random access channel
configurations of the M beams.
[0239] In a feasible implementation, the receiving module 52 is
configured to receive the validity period of the random access
channel configurations of the M beams that is sent by the first
network device.
[0240] The processing module 53 is configured to: after the
validity period expires, release the random access channel
configurations of the M beams.
[0241] Optionally, the sending module 51 is further configured to
send strength threshold information or quality threshold
information of a beam signal to the terminal through system
information.
[0242] The communications apparatus described in this embodiment
may be configured to execute the technical solutions executed by
the target base station or a chip inside the target base station in
the foregoing method embodiments. An implementation principle and a
technical effect of the communications apparatus are similar to
those of the foregoing method embodiments. For functions of the
modules, refer to corresponding descriptions in the method
embodiments. Details are not described herein.
[0243] FIG. 1o is a schematic structural diagram of a network
device according to an embodiment of this application. As shown in
FIG. 10, the network device in this embodiment may include a
processor 61 and a transceiver 62. The processor 61 is
communicatively connected to the transceiver 62.
[0244] In hardware implementation, the receiving module 52 and the
sending module 51 may be the transceiver 62 in this embodiment.
Alternatively, the transceiver 62 includes a transmitter and a
receiver; in this case, the receiving module 52 may be the receiver
of the transceiver 62, and the sending module 51 may be the
transmitter of the transceiver 62. The processing module 53 may be
embedded in or independent of the processor 61 of the network
device in a form of hardware.
[0245] The transceiver 62 may include necessary radio frequency
communications devices such as a frequency mixer. The processor 61
may include at least one of a CPU, a DSP, an MCU, an ASIC, or an
FPGA.
[0246] Optionally, the network device in this embodiment may
further include a memory 63. The memory 63 is configured to store a
program instruction. The processor 61 is configured to invoke the
program instruction in the memory 63 to execute the foregoing
solutions.
[0247] The program instruction may be implemented in a form of a
software functional unit and can be sold or used as an independent
product. The memory 63 may be a computer readable storage medium in
any form. Based on such understanding, all or some of the technical
solutions of this application may be represented in a form of a
software product, and the software product includes several
instructions for instructing a computer device, which may be
specifically the processor 61, to perform all or some of the steps
of the network device in the embodiments of this application. The
computer readable storage medium includes various media that can
store program code, such as a USB flash drive, a removable hard
disk, a ROM, a RAM, a magnetic disk, and a compact disc.
[0248] The network device in this embodiment may be configured to
execute the technical solutions of the target base station in the
foregoing method embodiments of this application. An implementation
principle and a technical solution of the network device are
similar to those of the foregoing method embodiments, and details
are not described herein.
[0249] It should be noted that module division in the embodiments
of this application is an example and is merely logical function
division. During actual implementation, there may be another
division manner. Functional modules in the embodiments of this
application may be integrated into one processing module, or each
of the modules may exist alone physically, or two or more modules
are integrated into one module. The integrated module may be
implemented in a form of hardware, or may be implemented in a form
of a software functional module.
[0250] When the integrated module is implemented in a form of a
software functional module and sold or used as an independent
product, the integrated module may be stored in a computer readable
storage medium. Based on such an understanding, the technical
solutions of this application essentially, or the part contributing
to the prior art, or all or some of the technical solutions may be
implemented in a form of a software product. The computer software
product is stored in a storage medium and includes several
instructions for instructing a computer device (which may be a
personal computer, a server, a network device, or the like) or a
processor to perform all or some of the steps of the methods
described in the embodiments of this application. The storage
medium includes various media that can store program code, such as
a USB flash drive, a removable hard disk, a read-only memory (ROM),
a random access memory (RAM), a magnetic disk, and a compact
disc.
[0251] All or some of the foregoing embodiments may be implemented
by using software, hardware, firmware, or any combination thereof.
When software is used to implement the embodiments, all or some of
the embodiments may be implemented in a form of a computer program
product. The computer program product includes one or more computer
instructions. When the computer program instructions are loaded and
executed on a computer, all or some of the procedures or functions
according to the embodiments of this application are generated. The
computer may be a general-purpose computer, a special-purpose
computer, a computer network, or another programmable apparatus.
The computer instructions may be stored in a computer readable
storage medium or may be transmitted from one computer readable
storage medium to another computer readable storage medium. For
example, the computer instructions may be transmitted from a
website, computer, server, or data center to another website,
computer, server, or data center in a wired (for example, a coaxial
cable, an optical fiber, or a digital subscriber line (DSL)) or
wireless (for example, infrared, radio, or microwave) manner. The
computer readable storage medium may be any usable medium
accessible by a computer, or a data storage device, such as a
server or a data center, integrating one or more usable media. The
usable medium may be a magnetic medium (for example, a floppy disk,
a hard disk, or a magnetic tape), an optical medium (for example, a
DVD), a semiconductor medium (for example, a solid state disk
(SSD)), or the like.
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