The present invention relates to the field of communications technologies,
and in particular, to a random access apparatus and method.
BACKGROUND
[0002] A spectrum is a basis of wireless communication. Spectrum resources
include a licensed spectrum resource and an unlicensed spectrum resource. Currently,
a main technology that uses the unlicensed spectrum resource is wireless fidelity
(Wireless Fidelity, WiFi). However, the WiFi has disadvantages in terms of mobility,
security, quality of service (Quality of Service, QoS), and concurrent processing of
multi-user scheduling. Therefore, applying an unlicensed spectrum to a Long Term
Evolution (Long-term Evolution, LTE) device can not only result in effective use of
the unlicensed spectrum resource, but also provide more effective wireless access and
meet a growing demand for mobile broadband service. Therefore, in a future mobile
communications scenario, both an LTE base station device and a WiFi device exist on
the unlicensed spectrum. One of feasible solutions of using the unlicensed spectrum
by the LTE base station is that the unlicensed spectrum is used as a secondary cell
(Secondary Cell, Scell) of LTE user equipment (User Equipment, UE) and is
configured for the UE, so that the LTE base station can perform data communication
with the UE by using the unlicensed spectrum.
[0003] In an LTE system and in an LTE Advanced (LTE-Advanced, LTE-A)
system, a random access procedure is required when data transmission is performed
for using a licensed spectrum. Random access procedures are classified into a
non-contention based random access procedure and a contention-based random access
procedure. Random access parameters used in a random access procedure of the prior
art, such as a physical random access channel resource and a parameter related to
random access, are notified to UE mainly by using system broadcast information; for
example, information such as a subframe or frequency channel number with the
2
physical random access channel (Physical Random Access Channel, PRACH)
resource, a random access code set, a random access code group, a maximum quantity
of sending times of a random access code, and a size of a random access response
message receiving window is notified to the UE. When the UE executes a
contention-based random access procedure, the UE selects a random access code
according to the random access parameters in the system message, and sends the
selected random access code on a selected random access channel. When the UE
executes a non-contention based random access procedure, the UE determines the
random access channel based on the random access parameters in the system message
and a random access channel mask sequence number notified by a base station by
using a physical downlink control channel (Physical Downlink Control Channel,
PDCCH) command, and sends, on the determined random access channel, the random
access code notified by using the PDCCH command to the base station. After sending
the random access code, the UE receives a random access response message in the
random access response message receiving window in the random access parameters
notified by the base station by using the system broadcast message.
[0004] Currently, a random access procedure is also required when data
transmission is performed for using an unlicensed spectrum. However, because a
contention and a collision may exist on an unlicensed spectrum resource, that is, the
unlicensed spectrum resource may be sometimes available or sometimes unavailable.
Therefore, if a PRACH resource on the unlicensed spectrum is also notified by using
system broadcast information, it may occur that a subframe of the configured PRACH
resource is unavailable, while an available subframe is not provided with the PRACH
resource, and consequently the random access procedure cannot be executed on the
unlicensed spectrum.
SUMMARY
[0005] Embodiments of the present invention provide a random access apparatus
and method, which can implement that a random access procedure is executed on an
unlicensed spectrum.
[0006] A first aspect of the embodiments of the present invention provides
random access user equipment, and the user equipment may include:
a receiving module, configured to receive a notification message sent by a
3
base station, where the notification message is used to instruct the user equipment UE
to execute a random access procedure, and the notification message carries at least
one of the following configuration parameters: a random access code used by the UE
to execute the random access procedure, or information about a physical random
access channel PRACH resource that is configured on an unlicensed spectrum and
that is used by the UE to execute the random access procedure;
a processing module, configured to determine, according to the
configuration parameter in the notification message received by the receiving module,
a PRACH resource used to execute the random access procedure; and
a sending module, configured to send the random access code to the base
station on the PRACH resource determined by the processing module; where
the receiving module is configured to receive a random access response
message sent by the base station, and determine, according to the random access
response message, that the random access procedure is successfully completed.
[0007] With reference to the first aspect, in a first possible implementation
manner, the notification message received by the receiving module may be
specifically a radio resource control RRC message, a media access control MAC
message, or a physical layer PHY message.
[0008] With reference to the first aspect, in a second possible implementation
manner, the random access code that is used by the UE to execute the random access
procedure and that is carried in the notification message received by the receiving
module is specifically a dedicated random access code, or information used to instruct
the UE to randomly select a random access code.
[0009] With reference to the first aspect, in a third possible implementation
manner, the information that is about the PRACH resource and that is carried in the
notification message received by the receiving module includes a frequency domain
location of the PRACH resource or a time domain location of the PRACH resource,
where the PRACH resource is configured on the unlicensed spectrum and is used by
the UE to execute the random access procedure.
[0010] With reference to any one of the first aspect to the third possible
implementation manner of the first aspect, in a fourth possible implementation
manner, when determining, according to the configuration parameter in the
notification message, the PRACH resource used to execute the random access
procedure, the processing module is specifically configured to:
4
determine, according to the information that is about the PRACH resource
and that is in the notification message, a location of the PRACH resource used to
execute the random access procedure; and
the sending module is configured to send, at the determined location of the
PRACH resource, the random access code carried in the notification message to the
base station.
[0011] With reference to any one of the first aspect to the third possible
implementation manner of the first aspect, in a fifth possible implementation manner,
the notification message received by the receiving module further includes at least one
of: a listening parameter that is used to listen on the unlicensed spectrum before the
UE sends the random access code to the base station, or a validity time for sending the
random access code by the UE, where
the listening parameter includes at least one of a listening time, a backoff
time, a power threshold, or an energy threshold.
[0012] With reference to the fifth possible implementation manner of the first
aspect, in a sixth possible implementation manner, the processing module is further
configured to:
listen to, according to the listening parameter, whether the determined
PRACH resource configured on the unlicensed spectrum is idle, or listen to, according
to the listening parameter, whether the determined unlicensed spectrum is idle; and
if it is detected, by means of listening, that the PRACH resource is idle or
the unlicensed spectrum is idle, instruct the sending module to send the random access
code to the base station on the PRACH resource during the validity time for sending
the random access code, or instruct the sending module to send the random access
code to the base station on the PRACH resource during the validity time for sending
the random access code and after backoff is randomly performed for a specified time
according to the backoff time.
[0013] With reference to the fourth possible implementation manner of the first
aspect or the sixth possible implementation manner of the first aspect, in a seventh
30 possible implementation manner, the receiving module is specifically configured to:
determine a value of a random access radio network temporary identifier
RA-RNTI according to protocol pre-configuration or a time domain location and a
frequency domain location that are of the PRACH resource; and
decode, by using the RA-RNTI in a random access response receiving
5
window, a scheduling command corresponding to the random access response
message, and decode the random access response message according to the
scheduling command.
[0014] With reference to the seventh possible implementation manner of the first
aspect, in an eighth possible implementation manner, a start location of the random
access response receiving window is specifically an N* sub frame after the UE sends
the random access code; or
a start location of the random access response receiving window is
specifically an N* subframe after the specified validity time; where
N is a non-zero natural number.
[0015] A second aspect of the embodiments of the present invention provides a
random access method, and the method may include:
receiving, by user equipment UE, a notification message sent by a base
station, where the notification message is used to instruct the UE to execute a random
access procedure, and the notification message carries at least one of the following
configuration parameters: a random access code used by the UE to execute the
random access procedure, or information about a physical random access channel
PRACH resource that is configured on an unlicensed spectrum and that is used by the
UE to execute the random access procedure;
determining, by the UE according to the configuration parameter in the
notification message, a PRACH resource used to execute the random access
procedure, and sending the random access code to the base station on the PRACH
resource; and
receiving, by the UE, a random access response message sent by the base
station, and determining, according to the random access response message, that the
random access procedure is successfully completed.
[0016] With reference to the second aspect, in a first possible implementation
manner, the notification message may be specifically a radio resource control RRC
message, a media access control MAC message, or a physical layer PHY message.
[0017] With reference to the second aspect, in a second possible implementation
manner, the random access code used by the UE to execute the random access
procedure is specifically a dedicated random access code, or information used to
instruct the UE to randomly select a random access code.
[0018] With reference to the second aspect, in a third possible implementation
6
manner, the information about the PRACH resource that is configured on the
unlicensed spectrum and that is used by the UE to execute the random access
procedure includes a frequency domain location of the PRACH resource or a time
domain location of the PRACH resource.
[0019] With reference to any one of the second aspect to the third possible
implementation manner of the second aspect, in a fourth possible implementation
manner, the determining, by the UE according to the configuration parameter in the
notification message, a PRACH resource used to execute the random access
procedure, and sending the random access code to the base station on the PRACH
resource includes:
determining, by the UE according to the information that is about the
PRACH resource and that is in the notification message, a location of the PRACH
resource used to execute the random access procedure, and sending, at the determined
location of the PRACH resource, the random access code carried in the notification
message to the base station.
[0020] With reference to any one of the second aspect to the third possible
implementation manner of the second aspect, in a fifth possible implementation
manner, the notification message further includes at least one of: a listening parameter
that is used to listen on the unlicensed spectrum before the UE sends the random
access code to the base station, or a validity time for sending the random access code
by the UE, where
the listening parameter includes at least one of a listening time, a backoff
time, a power threshold, or an energy threshold.
[0021] With reference to the fifth possible implementation manner of the second
aspect, in a sixth possible implementation manner, before the sending the random
access code to the base station on the PRACH resource, the method further includes:
listening to, by the UE according to the listening parameter, whether the
determined PRACH resource configured on the unlicensed spectrum is idle, or
listening to, by the UE according to the listening parameter, whether the determined
unlicensed spectrum is idle; and
if it is detected, by means of listening, that the PRACH resource is idle or
the unlicensed spectrum is idle, sending the random access code to the base station on
the PRACH resource during the validity time for sending the random access code, or
sending the random access code to the base station on the PRACH resource during the
7
validity time for sending the random access code and after backoff is randomly
performed for a specified time according to the backoff time.
[0022] With reference to the fourth possible implementation manner of the second
aspect or the sixth possible implementation manner of the second aspect, in a seventh
possible implementation manner, the receiving, by the UE, a random access response
message sent by the base station includes:
determining, by the UE, a value of a random access radio network
temporary identifier RA-RNTI according to protocol pre-configuration or a time
domain location and a frequency domain location that are of the PRACH resource;
and
decoding, by the UE by using the RA-RNTI in a random access response
receiving window, a scheduling command corresponding to the random access
response message, and decoding the random access response message according to
the scheduling command.
[0023] With reference to the seventh possible implementation manner of the
second aspect, in an eighth possible implementation manner, a start location of the
random access response receiving window is specifically an N* subframe after the
UE sends the random access code; or
a start location of the random access response receiving window is
specifically an N* subframe after the specified validity time; where
N is a non-zero natural number.
[0024] In the embodiments of the present invention, user equipment may
determine, according to a notification message sent by a base station, a PRACH
resource that is configured on an unlicensed spectrum and that is used to execute a
random access procedure, send a random access code to the base station on the
determined PRACH resource, and further receive, in a random access response
receiving window configured by the base station, a random access response message
sent by the base station, which can reduce a delay of implementing the random access
procedure on the unlicensed spectrum, and reduce a probability of a collision during
implementation of the random access procedure on the unlicensed spectrum, thereby
implementing that the random access procedure is better executed on the unlicensed
spectrum, and enhancing user experience of implementing the random access
procedure on the unlicensed spectrum.
8
BRIEF DESCRIPTION OF DRAWINGS
[0025] To describe the technical solutions in the embodiments of the present
invention or in the prior art more clearly, the following briefly describes the
accompanying drawings required for describing the embodiments. Apparently, the
accompanying drawings in the following description show merely some embodiments
of the present invention, and a person of ordinary skill in the art may still derive other
drawings from these accompanying drawings without creative efforts.
[0026] FIG. 1 is a schematic interaction diagram of a contention-based random
access procedure in implementing a random access procedure on a licensed spectrum
in the prior art;
[0027] FIG. 2 is a schematic interaction diagram of a non-contention based
random access procedure in implementing a random access procedure on a licensed
spectrum in the prior art;
[0028] FIG. 3 is a schematic structural diagram of a first embodiment of random
access user equipment according to an embodiment of the present invention;
[0029] FIG. 4 is a schematic structural diagram of a second embodiment of
random access user equipment according to an embodiment of the present invention;
[0030] FIG. 5 is a schematic flowchart of a first embodiment of a random access
method according to an embodiment of the present invention; and
[0031] FIG. 6 is a schematic flowchart of a second embodiment of a random
access method according to an embodiment of the present invention.
DESCRIPTION OF EMBODIMENTS
[0032] The following clearly and completely describes the technical solutions in
the embodiments of the present invention with reference to the accompanying
drawings in the embodiments of the present invention. Apparently, the described
embodiments are merely some but not all of the embodiments of the present invention.
All other embodiments obtained by a person of ordinary skill in the art based on the
embodiments of the present invention without creative efforts shall fall within the
protection scope of the present invention.
[0033] In specific implementation, to better describe a specific implementation
process of implementing a random access procedure on an unlicensed spectrum, the
9
following briefly describes a process of implementing random access on a licensed
spectrum in the prior art.
[0034] In the prior art, implementing the random access procedure on the licensed
spectrum may be classified into a non-contention based random access procedure and
5 a contention-based random access procedure. Referring to FIG. 1, FIG. 1 is a
schematic interaction diagram of the contention-based random access procedure in
implementing the random access procedure on the licensed spectrum in the prior art,
including:
[0035] Step 1: UE sends a preamble to a base station on an available PRACH
10 resource.
[0036] In the prior art, in the contention-based random access procedure, the UE
randomly selects a preamble, and sends the preamble to the base station on the
available PRACH resource. The foregoing preamble and the available PRACH
resource are notified to the UE by the base station by using a system broadcast
15 message. On the licensed spectrum, because a PRACH resource is a resource on the
licensed spectrum, neither contention nor collision exists. Therefore, the PRACH
resource notified to the UE by the base station by using the system broadcast message
is the available PRACH resource, and the UE may directly send information such as
the preamble to the base station on the available PRACH resource notified by the
20 foregoing base station.
[0037] Step 2: The base station sends a random access response message to the
UE.
[0038] After receiving the preamble sent by the UE, the base station may send the
random access response message to the UE. The random access response message
25 carries uplink grant information and UE uplink timing advance information.
[0039] Step 3: The UE sends uplink information according to uplink grant
information and timing advance information that are carried in the random access
response message.
[0040] After receiving the random access response message sent by the base
30 station, the UE may send the uplink information to the base station according to the
uplink grant information and the timing advance information that are carried in the
random access response message. The forgoing uplink information includes content
that can identify the UE. That is, the base station may identify the UE according to the
uplink information sent by the UE, and may further send a contention resolution
10
message to the UE.
[0041] Step 4: The base station sends a contention resolution message to the UE.
[0042] After the base station sends the contention resolution message to the UE,
the UE may determine, according to the received contention resolution message,
whether the random access procedure is successfully completed. If it is learned, by
means of determining, that the random access procedure is successfully completed,
the UE may execute subsequent data receiving and sending procedures.
[0043] It may be learned from the foregoing that, in the prior art, when UE
executes a contention-based random access procedure, the UE selects a random access
code according to a random access parameter notified in a system broadcast message,
and sends the selected random access code on a selected random access channel.
[0044] Referring to FIG. 2, FIG. 2 is a schematic interaction diagram of a
non-contention based random access procedure in implementing a random access
procedure on a licensed spectrum in the prior art, including:
[0045] Step 1: Abase station configures a dedicated preamble for UE.
[0046] In the prior art, in the non-contention based random access procedure, the
base station first configures a dedicated preamble for the UE. Optionally, the base
station may further configure, for the UE, a PRACH resource for sending the
preamble, and the UE may send information such as the preamble to the base station
according to the preamble and the PRACH resource that are configured by the base
station.
[0047] Step 2: The UE sends the dedicated preamble to the base station on an
available PRACH resource.
[0048] In the prior art, because the random access procedure is performed on the
licensed spectrum, neither contention nor collision exists. Therefore, the base station
may configure the available PRACH resource for the UE, and after receiving the
preamble and the PRACH resource that are configured by the base station, the UE
may send the dedicated preamble to the base station on the available PRACH
resource.
[0049] Step 3: The base station sends a random access response message to the
user equipment.
[0050] After receiving the preamble sent by the UE, the base station sends the
random access response message to the UE, where the foregoing random access
response message carries uplink grant information and UE uplink timing advance
11
information. After receiving the random access response message sent by the base
station, the UE may consider that the random access procedure is successfully
completed, and may further execute subsequent data receiving and sending
procedures.
5 [0051] It may be learned from the foregoing that, in the prior art, in a
non-contention based random access procedure, UE sends a dedicated preamble to a
base station on an available PRACH resource according to the preamble and the
available PRACH resource that are notified in a system broadcast message, receives,
in a random access response message receiving window sent in the system broadcast
10 message, a random access response message sent by the base station, and completes
the random access procedure.
[0052] In the prior art, because the random access procedure is performed on a
licensed spectrum, neither contention nor collision exists in a spectrum resource.
Therefore, the base station may obtain the available PRACH resource, and may
15 further notify the UE of the available PRACH resource by using the system broadcast
message, and the UE may directly send information such as the preamble to the base
station on the PRACH resource notified by the base station.
[0053] A random access procedure described in the embodiments of the present
invention is a random access procedure implemented on an unlicensed spectrum.
20 Because a contention or a collision may exist on a resource on the unlicensed
spectrum, that is, the unlicensed spectrum resource may be sometimes available or
sometimes unavailable. If a base station sends resource information to UE by using a
system broadcast message, it may be that the resource is available when the base
station sends the resource information to the UE, but when the UE receives the system
25 broadcast message sent by the base station, the resource information is occupied, that
is, the resource is unavailable when the UE executes the random access procedure.
Therefore, in the embodiments of the present invention, the base station cannot notify
the UE of information about the available resource by using the system broadcast
message. If a PRACH resource on the unlicensed spectrum is notified to the UE by
30 using a method of the system broadcast message, it may occur that a subframe of the
configured PRACH resource is unavailable, while an available subframe is not
provided with the PRACH resource, so that the UE cannot execute the random access
procedure on the unlicensed spectrum. To resolve the foregoing technical problem, the
embodiments of the present invention provide a random access method. The UE may
12
learn a configuration parameter of random access in real time from a notification
message sent by the base station, and the UE may select the PRACH resource
according to the configuration parameter carried in the notification message, and send
information to the base station.
[0054] Referring to FIG. 3, FIG. 3 is a schematic structural diagram of a first
embodiment of random access user equipment according to an embodiment of the
present invention. The user equipment described in this embodiment includes:
a receiving module 10, configured to receive a notification message sent
by a base station, where the notification message is used to instruct the user
equipment UE to execute a random access procedure, and the notification message
carries at least one of the following configuration parameters: a random access code
used by the UE to execute the random access procedure, or information about a
physical random access channel PRACH resource that is configured on an unlicensed
spectrum and that is used by the UE to execute the random access procedure;
a processing module 20, configured to determine, according to the
configuration parameter in the notification message received by the receiving module,
a PRACH resource used to execute the random access procedure; and
a sending module 30, configured to send the random access code to the
base station on the PRACH resource determined by the processing module; where
the receiving module 10 is configured to receive a random access response
message sent by the base station, and determine, according to the random access
response message, that the random access procedure is successfully completed.
[0055] In specific implementation, because a contention and a collision may exist
on an unlicensed spectrum resource, before instructing the UE to execute the random
access procedure, the base station cannot determine a location of the specific available
PRACH resource when the UE executes the random access procedure. Therefore, the
base station cannot send the available PRACH resource to the UE by using system
broadcast information, and the base station can instruct, only when the UE is required
to execute the random access procedure and by using the notification message, the UE
to execute the random access procedure and notify the UE of the available PRACH
resource by using the notification message.
[0056] In some feasible implementation manners, when the UE is required by the
base station to execute the random access procedure on the unlicensed spectrum, the
base station may instruct, by sending the notification message to the UE, the UE to
execute the random access procedure, and the UE may receive, by using the receiving
module 10, the notification message sent by the base station. Specifically, the
notification message received by the foregoing receiving module 10 may carry the
random access code used by the UE to execute the random access procedure and the
information about the PRACH resource that is configured on the unlicensed spectrum
and that is used by the UE to execute the random access procedure. In specific
implementation, the foregoing notification message may be specifically an RRC
message, an MAC message, or a PHY message. Specifically, the random access code
carried in the foregoing notification message may be a dedicated random access code,
or may be information used to instruct the UE to randomly select a random access
code. The information about the PRACH resource that is configured on the unlicensed
spectrum and that is used by the foregoing UE to execute the random access
procedure may include a frequency domain location of the foregoing PRACH
resource, a time domain location of the foregoing PRACH resource, or the like, for
example, a specific PRACH resource, or a subframe that is in a time domain and in
which the PRACH resource exists. The foregoing time domain information may be an
absolute frame number and an absolute subframe number, or a subframe offset (for
example, a sixth subframe behind a subframe of the foregoing notification message)
relative to the foregoing notification message. This embodiment of the present
invention imposes no limitation on the frequency domain location or the time domain
location of the PRACH resource. That is, when instructing, by sending the
notification message to the UE, the UE to execute the random access procedure, the
base station may notify the UE of an obtained specific location of the available
PRACH resource, and may further send, to the UE, the random access code used by
the UE to execute the random access. The UE may receive the foregoing notification
message by using the receiving module 10, determine, by using the processing
module 20 according to the PRACH resource notified in the notification message
received by the foregoing receiving module 10, the PRACH resource used to execute
the random access procedure, and may further send, by using the sending module 30,
the random access code to the base station on the PRACH resource determined by the
foregoing processing module 20.
[0057] In some feasible implementation manners, the notification message may be
sent to the UE by using a cell operating on a licensed spectrum when the base station
sends the notification message of executing the random access procedure to the UE.
14
Specifically, the notification message may be sent to the UE by using a primary cell,
or be sent to the UE by using a secondary cell. The UE may obtain, by using the
foregoing primary cell or secondary cell, the notification message sent by the base
station, where the foregoing primary cell or secondary cell may be pre-configured in a
protocol, or may be configured by using another message, which is not limited herein.
[0058] In some feasible implementation manners, after the receiving module 10 of
the UE receives the notification message sent by the base station, the processing
module 20 may determine, according to the configuration parameter carried in the
notification message received by the receiving module 10, the PRACH resource used
to execute the random access procedure. Specifically, the configuration parameter
carried in the notification message received by the foregoing receiving module 10
may include the random access code used by the foregoing UE to execute the random
access procedure, the PRACH resource used by the foregoing UE to execute the
random access procedure, and the like; the PRACH resource carried in the foregoing
notification message is the PRACH resource that is configured on the unlicensed
spectrum and that is obtained by the base station, and is the available PRACH
resource determined by the base station. However, because of an inconsistency
between a location of the base station and a location of the UE, the UE may be in a
moving state. Therefore, after the base station determines the available PRACH
resource and notifies the UE of the available PRACH resource by using the
notification message, if the UE is in the moving state, the PRACH resource sent by
the foregoing base station may be unavailable in a current location of the UE when
the UE executes the random access procedure according to the notification message
sent by the base station; after the receiving module 10 of the UE receives the
notification message sent by the base station and obtains the available PRACH
resource, the processing module 20 further needs to determine a location of a specific
to-be-used PRACH resource in the foregoing available PRACH resource according to
an actual location of the UE. That is, the processing module 20 of the UE may
determine, according to the information that is about the PRACH resource and that is
carried in the foregoing notification message, the location of the available PRACH
resource, that is, the location of the available PRACH resource in the current location
of the UE. After the UE determines the location of the specific available PRACH
resource by using the processing module 20, the sending module 30 may send the
random access code to the base station at the location of the foregoing PRACH
15
resource, where the foregoing random access code is the random access code carried
in the notification message. In specific implementation, for a specific implementation
process in which the foregoing receiving module receives the notification message
sent by the base station, refer to step S101 in a first embodiment of a random access
method provided in an embodiment of the present invention, and details are not
described herein again.
[0059] In some feasible implementation manners, after the sending module 30 of
the UE sends the random access code to the base station, the receiving module 10 may
receive, in a random access response receiving window configured by the base station,
the random access response message sent by the base station, where the foregoing
random access response receiving window may be learned from the notification
message received by the foregoing receiving module 10, that is, the notification
message received by the foregoing receiving module 10 may carry the random access
response receiving window configured by the base station. In specific implementation,
a scheduling command corresponding to the random access response message that is
sent by the base station to the UE and that is received by the receiving module 10 may
be scrambled by using an RA-RNTI. Before receiving the foregoing random access
response message, the receiving module 10 of the UE further needs to determine a
value of the foregoing RA-RNTI. Specifically, the value of the foregoing RA-RNTI
may be fixed in the protocol, or may be determined according to a time frequency
location and a frequency domain location that are of the PRACH resource actually
used by the UE, or be determined by using the received notification message; that is,
the base station may notify the UE of the value of the foregoing RA-RNTI by using
the foregoing notification message, and the receiving module 10 of the UE may
determine the value of the random access radio network temporary identifier
RA-RNTI according to protocol pre-configuration or a time domain location and a
frequency domain location that are of the PRACH resource. After determining the
value of the foregoing RA-RNTI, the receiving module 10 of the UE may decode, in
the random access response receiving window by using the foregoing RA-RNTI, the
scheduling command corresponding to the foregoing random access response
message, and decode the random access response message according to the foregoing
scheduling command, so as to obtain the random access response message sent by the
base station. In specific implementation, a start location of the foregoing random
access response receiving window may be an N* subframe after the UE sends the
16
random access code, or may be an Nth subframe after a specified time, that is, the start
location of the foregoing random access response receiving window may be fixed in
the protocol as the Nth subframe after the UE sends the random access code, and the
start location of the random access response receiving window is notified to the UE
5 by using the foregoing notification message, where N may be a non-zero natural
number. In this way, no matter when the UE executes the random access procedure
(sending the random access code to the base station), the random access response
receiving window may start from the Nth subframe after the UE sends the random
access code, or start from the Nth subframe after the specified time, which does not
10 cause ambiguity, and may better implement the random access procedure on the
unlicensed spectrum. In specific implementation, for a specific implementation
process in which the foregoing processing module and sending module send the
random access code to the base station according to the notification message sent by
the base station, the foregoing processing module and receiving module receive,
15 according to the notification message sent by the base station, the random access
response message sent by the base station, refer to steps S102 to S103 in the first
embodiment of the random access method provided in the embodiment of the present
invention, and details are not described herein again.
[0060] The UE described in this embodiment of the present invention may receive
20 a notification message sent by a base station, where the foregoing notification
message carries a random access code used by the UE to execute a random access
procedure and a PRACH resource that is configured on an unlicensed spectrum and
that is used by the UE to execute the random access procedure. The UE may
determine, according to the foregoing notification message, a PRACH resource used
25 by the UE to execute the random access procedure, send the random access code to
the base station on the resource, and further receive, in a random access response
receiving window configured by the base station, a random access response message
sent by the base station, which implements that the random access procedure is
executed on the unlicensed spectrum, reduces a probability of a collision in the
30 random access procedure on the unlicensed spectrum, and enhances user experience
of the random access procedure on the unlicensed spectrum.
[0061] Referring to FIG. 4, FIG. 4 is a schematic structural diagram of a second
embodiment of random access user equipment according to an embodiment of the
present invention. The user equipment described in this embodiment includes:
17
a receiving module 40, configured to receive a notification message sent
by a base station, where the notification message is used to instruct the user
equipment UE to execute a random access procedure, and the notification message
carries at least one of the following configuration parameters: a random access code
5 used by the UE to execute the random access procedure, or information about a
physical random access channel PRACH resource that is configured on an unlicensed
spectrum and that is used by the UE to execute the random access procedure;
a processing module 50, configured to determine, according to the
configuration parameter in the notification message received by the receiving module,
10 a PRACH resource used to execute the random access procedure; and
a sending module 30, configured to send the random access code to the
base station on the PRACH resource determined by the processing module; where
the receiving module 40 is configured to receive a random access response
message sent by the base station, and determine, according to the random access
15 response message, that the random access procedure is successfully completed.
[0062] In specific implementation, because a contention and a collision may exist
on an unlicensed spectrum resource, before instructing the UE to execute the random
access procedure, the base station cannot determine a location of the specific available
PRACH resource when the UE executes the random access procedure. Therefore, the
20 base station cannot send the available PRACH resource to the UE by using system
broadcast information, and the base station can instruct, only when the UE is required
to execute the random access procedure and by using the notification message, the UE
to execute the random access procedure and notify the UE of the available PRACH
resource by using the notification message.
25 [0063] In some feasible implementation manners, when the UE is required by the
base station to execute the random access procedure on the unlicensed spectrum, the
base station may instruct, by sending the notification message to the UE, the UE to
execute the random access procedure, and the UE may receive, by using the receiving
module 40, the notification message sent by the base station. Specifically, the
30 notification message received by the foregoing receiving module 40 may carry the
random access code used by the UE to execute the random access procedure and the
information about the PRACH resource that is configured on the unlicensed spectrum
and that is used by the UE to execute the random access procedure. In specific
implementation, the foregoing notification message may be specifically an RRC
18
message, an MAC message, or a PHY message. Specifically, the random access code
carried in the foregoing notification message may be a dedicated random access code,
or may be information used to instruct the UE to randomly select a random access
code. The information about the PRACH resource that is configured on the unlicensed
5 spectrum and that is used by the foregoing UE to execute the random access
procedure may include a frequency domain location of the foregoing PRACH
resource, a time domain location of the foregoing PRACH resource, or the like, for
example, a specific PRACH resource, or a subframe that is in a time domain and in
which the PRACH resource exists. The foregoing time domain information may be an
10 absolute frame number and an absolute subframe number, or a subframe offset (for
example, a sixth subframe behind a subframe of the foregoing notification message)
relative to the foregoing notification message. This embodiment of the present
invention imposes no limitation on the frequency domain location or the time domain
location of the PRACH resource. That is, when the base station instructs, by sending
15 the notification message to the UE, the UE to execute the random access procedure,
the UE may receive, by using the receiving module 40, the notification message sent
by the base station, and learn the specific location of the available PRACH resource
according to the notification message received by the receiving module 40, and may
further send, to the UE, the random access code used by the UE to execute the random
20 access. The processing module 50 of the UE may determine, according to the PRACH
resource notified in the notification message received by the receiving module 40, the
PRACH resource used to execute the random access procedure, and send, by using
the sending module 30, the random access code to the base station on the PRACH
resource determined by the foregoing processing module 50.
25 [0064] In some feasible implementation manners, the notification message may be
sent to the UE by using a cell operating on a licensed spectrum when the base station
sends the notification message of executing the random access procedure to the UE.
Specifically, the notification message may be sent to the UE by using a primary cell,
or be sent to the UE by using a secondary cell. The receiving module 40 of the UE
30 may receive the notification message sent by the base station by using the primary cell
or the secondary cell, where the foregoing primary cell or secondary cell may be
pre-configured in a protocol, or may be configured by using another message, which
is not limited herein. In specific implementation, for a specific implementation
process in which the foregoing receiving module receives the notification message
19
sent by the base station, refer to step S201 in a first embodiment of a random access
method provided in an embodiment of the present invention, and details are not
described herein again.
[0065] In some feasible implementation manners, the foregoing processing
5 module 50 is specifically configured to:
determine, according to the information that is about the PRACH resource
and that is in the notification message, a location of the PRACH resource used to
execute the random access procedure; and
the sending module 30 is configured to send, at the determined location of
10 the PRACH resource, the random access code carried in the notification message to
the base station.
[0066] In some feasible implementation manners, the notification message
received by the receiving module 40 further includes at least one of: a listening
parameter that is used to listen on the unlicensed spectrum before the UE sends the
15 random access code to the base station, or a validity time for sending the random
access code by the UE, where
the listening parameter includes at least one of a listening time, a backoff
time, a power threshold, or an energy threshold.
[0067] The processing module 50 is further configured to:
20 listen to, according to the listening parameter, whether the determined
PRACH resource configured on the unlicensed spectrum is idle, or listen to, according
to the listening parameter, whether the determined unlicensed spectrum is idle; and
if it is detected, by means of listening, that the PRACH resource is idle or
the unlicensed spectrum is idle, instruct the sending module 30 to send the random
25 access code to the base station on the PRACH resource during the validity time for
sending the random access code, or instruct the sending module 30 to send the
random access code to the base station on the PRACH resource during the validity
time for sending the random access code and after backoff is randomly performed for
a specified time according to the backoff time.
30 [0068] In some feasible implementation manners, after the receiving module 40 of
the UE receives the notification message sent by the base station, the processing
module 50 may determine, according to the configuration parameter carried in the
notification message received by the receiving module 40, the PRACH resource used
to execute the random access procedure. Specifically, the configuration parameter
20
carried in the notification message received by the foregoing receiving module 40
may include the random access code used by the foregoing UE to execute the random
access procedure, the PRACH resource used by the foregoing UE to execute the
random access procedure, and the like; the PRACH resource carried in the foregoing
5 notification message is the PRACH resource that is configured on the unlicensed
spectrum and that is obtained by the base station, and is the available PRACH
resource determined by the base station. However, because of an inconsistency
between a location of the base station and a location of the UE, the UE may be in a
moving state. Therefore, after the base station determines the available PRACH
10 resource and notifies the UE of the available PRACH resource by using the
notification message, if the UE is in the moving state, the PRACH resource sent by
the foregoing base station may be unavailable in a current location of the UE when
the UE executes the random access procedure according to the notification message
sent by the base station; after the UE receives, by using the receiving module 40, the
15 notification message sent by the base station and obtains the available PRACH
resource, the processing module 50 may further determine a location of a specific
to-be-used PRACH resource in the foregoing available PRACH resource according to
an actual location of the UE. Specifically, the base station may send, by using the
foregoing notification message, the listening parameter that is used to listen to the
20 PRACH resource before the UE sends the random access code to the base station to
the UE when the UE executes the random access procedure. After receiving the
notification message sent by the foregoing base station, the receiving module 40 of
the UE may obtain, from the foregoing notification message, the listening parameter
that is used to listen to the PRACH resource. The PRACH resource listened to by the
25 foregoing UE is the PRACH resource configured on the unlicensed spectrum; that is,
the UE may listen to, by using the processing module 50, the PRACH resource sent
by the base station to the UE by using the notification message, and determine the
specific available PRACH resource. The foregoing listening parameter may include
the listening time, the backoff time, the power threshold, the energy threshold, and the
30 like. In specific implementation, the notification message that is sent by the base
station and that is received by the receiving module 40 of the foregoing UE may
further carry the validity time for sending the random access code by the UE; that is,
the sending module 30 of the UE may send the random access code to the base station
on the determined available PRACH resource during the foregoing validity time.
21
Specifically, after determining, according to the notification message sent by the base
station, the PRACH resource used by the UE to execute the random access procedure,
the processing module 50 of the UE may listen to the foregoing PRACH resource
according to the foregoing listening parameter, that is, listen to whether the PRACH
5 resource configured on the foregoing unlicensed spectrum is idle, or listen to,
according to the listening parameter, whether the determined unlicensed spectrum is
idle, and if the processing module 50 detects, by means of listening, that the PRACH
resource is idle or the unlicensed spectrum is idle, the sending module 30 may send
the random access code to the base station on the foregoing determined PRACH
10 resource during the foregoing validity time for sending the random access code. In
specific implementation, after the processing module 50 of the UE listens to,
according to the foregoing listening parameter, the PRACH resource configured on
the unlicensed spectrum and determines the available PRACH resource, the sending
module 30 may further send, after the random backoff time (that is, the specified time)
15 according to the backoff time in the foregoing listening parameter, the random access
code to the base station on the foregoing available PRACH resource, where the
foregoing random access code is the random access code carried in the notification
message.
[0069] In some feasible implementation manners, the foregoing receiving module
20 40 is specifically configured to:
determine a value of a random access radio network temporary identifier
RA-RNTI according to protocol pre-configuration or a time domain location and a
frequency domain location that are of the PRACH resource; and
decode, by using the RA-RNTI in a random access response receiving
25 window, a scheduling command corresponding to the random access response
message, and decode the random access response message according to the
scheduling command.
[0070] In some feasible implementation manners, after the sending module 50 of
the UE sends the random access code to the base station, the receiving module 40 may
30 receive, in the random access response receiving window configured by the base
station, the random access response message sent by the base station, where the
foregoing random access response receiving window may be learned from the
notification message received by the receiving module 40, that is, the notification
message that is sent by the base station to the UE and that is received by the foregoing
22
receiving module 40 may carry the random access response receiving window
configured by the base station. In specific implementation, the scheduling command
corresponding to the random access response message sent by the base station to the
UE may be scrambled by using the RA-RNTI. Before receiving the foregoing random
5 access response message, the receiving module 40 of the UE further needs to
determine the value of the foregoing RA-RNTI. Specifically, the value of the
foregoing RA-RNTI may be fixed in the protocol, or may be determined according to
a time frequency location and a frequency domain location that are of the PRACH
resource actually used by the UE, or be determined by using the notification message
10 sent by the base station; that is, the base station may notify the UE of the value of the
foregoing RA-RNTI by using the foregoing notification message, and after receiving
the notification message sent by the base station, the receiving module 40 of the UE
may determine the value of the random access radio network temporary identifier
RA-RNTI according to the protocol pre-configuration or a time domain location and a
15 frequency domain location that are of the PRACH resource. After determining the
value of the foregoing RA-RNTI, the receiving module 40 of the UE may decode, in
the random access response receiving window by using the foregoing RA-RNTI, the
scheduling command corresponding to the foregoing random access response
message, and decode the random access response message according to the foregoing
20 scheduling command, so as to obtain the random access response message sent by the
base station. In specific implementation, a start location of the foregoing random
access response receiving window may be an Nth subframe after the UE sends the
random access code, or may be an Nth subframe after the specified time, that is, the
start location of the foregoing random access response receiving window may be
25 fixed in the protocol as the Nth subframe after the UE sends the random access code,
and the start location of the random access response receiving window is notified to
the UE by using the foregoing notification message, where N may be a non-zero
natural number. In this way, no matter when the UE executes the random access
procedure (sending the random access code to the base station), the random access
30 response receiving window may start from the Nth subframe after the UE sends the
random access code, or start from the Nth subframe after the specified time, which
does not cause ambiguity, and may better implement the random access procedure on
the unlicensed spectrum. In specific implementation, for a specific implementation
process in which the foregoing processing module and sending module send the
23
random access code to the base station according to the notification message sent by
the base station, the foregoing processing module and receiving module receive,
according to the notification message sent by the base station, the random access
response message sent by the base station, refer to steps S202 to S205 in the first
5 embodiment of the random access method provided in the embodiment of the present
invention, and details are not described herein again.
[0071] The UE described in this embodiment of the present invention may receive
a notification message sent by a base station, where the foregoing notification
message carries a random access code used by the UE to execute a random access
10 procedure and a PRACH resource that is configured on an unlicensed spectrum and
that is used by the UE to execute the random access procedure. The UE may listen to,
according to a listening parameter that is set in the notification message, the PRACH
resource that is configured on the unlicensed spectrum and that is sent by the base
station, determine, according to the foregoing notification message, a PRACH
15 resource used by the UE to execute the random access procedure, send the random
access code to the base station on the resource, and further receive, in a random
access response receiving window configured by the base station, a random access
response message sent by the base station, which implements that the random access
procedure is executed on the unlicensed spectrum, reduces a probability of a collision
20 in the random access procedure on the unlicensed spectrum, and enhances user
experience of the random access procedure on the unlicensed spectrum.
[0072] Referring to FIG. 5, FIG. 5 is a schematic flowchart of a first embodiment
of a random access method according to an embodiment of the present invention. The
random access method described in this embodiment includes the following steps:
25 [0073] S101. User equipment UE receives a notification message sent by a base
station.
[0074] In specific implementation, because a contention and a collision may exist
on an unlicensed spectrum resource, before instructing the UE to execute a random
access procedure, the base station cannot determine a location of a specific available
30 PRACH resource when the UE executes the random access procedure. Therefore, the
base station cannot send the available PRACH resource to the UE by using system
broadcast information, and the base station can instruct, only when the UE is required
to execute the random access procedure and by using the notification message, the UE
to execute the random access procedure and notify the UE of the available PRACH
24
resource by using the notification message.
[0075] In some feasible implementation manners, when the UE is required by the
base station to execute the random access procedure on an unlicensed spectrum, the
base station may instruct, by sending the notification message to the UE, the UE to
5 execute the random access procedure, and the UE may receive the notification
message sent by the base station, and execute the random access procedure according
to the foregoing notification message. Specifically, the foregoing notification message
may carry a random access code used by the UE to execute the random access
procedure or information about a PRACH resource that is configured on the
10 unlicensed spectrum and that is used by the UE to execute the random access
procedure. In specific implementation, the foregoing notification message may be
specifically a radio resource control (Radio Resource Control, RRC) message, a
media access control (Media Access Control, MAC) message, or a physical layer
(Physical Layer, PHY) message. Specifically, the random access code carried in the
15 foregoing notification message may be a dedicated random access code, or may be
information used to instruct the UE to randomly select a random access code. The
information about the PRACH resource that is configured on the unlicensed spectrum
and that is used by the foregoing UE to execute the random access procedure may
include a frequency domain location of the foregoing PRACH resource, a time
20 domain location of the foregoing PRACH resource, or the like, for example, a specific
PRACH resource, or a subframe that is in a time domain and in which the PRACH
resource exists. The foregoing time domain information may be an absolute frame
number and an absolute subframe number, or a subframe offset (for example, a sixth
subframe behind a subframe of the foregoing notification message) relative to the
25 foregoing notification message. This embodiment of the present invention imposes no
limitation on the frequency domain location or the time domain location of the
PRACH resource. That is, when instructing, by sending the notification message to
the UE, the UE to execute the random access procedure, the base station may notify
the UE of an obtained specific location of the available PRACH resource, and may
30 further send, to the UE, the random access code used by the UE to execute the random
access. The UE may determine, according to the PRACH resource notified in the
notification message, a PRACH resource used to execute the random access
procedure, and send the random access code to the base station on the foregoing
determined PRACH resource.
25
[0076] In some feasible implementation manners, the notification message may be
sent to the UE by using a cell operating on a licensed spectrum when the base station
sends the notification message of executing the random access procedure to the UE.
Specifically, the notification message may be sent to the UE by using a primary cell,
5 or be sent to the UE by using a secondary cell. The UE may obtain, by using the
foregoing primary cell or secondary cell, the notification message sent by the base
station, where the foregoing primary cell or secondary cell may be pre-configured in a
protocol, or may be configured by using another message, which is not limited herein.
[0077] S102. The UE determines, according to a configuration parameter in the
10 notification message, a PRACH resource used to execute a random access procedure,
and sends the random access code to the base station on the PRACH resource.
[0078] S103. The UE receives a random access response message sent by the base
station, and determines, according to the random access response message, that the
random access procedure is successfully completed.
15 [0079] In some feasible implementation manners, after receiving the notification
message sent by the base station, the UE may determine, according to the
configuration parameter carried in the notification message, the PRACH resource
used to execute the random access procedure. Specifically, the configuration
parameter carried in the foregoing notification message may include the random
20 access code used by the foregoing UE to execute the random access procedure, the
PRACH resource used by the foregoing UE to execute the random access procedure,
and the like; the PRACH resource carried in the foregoing notification message is the
PRACH resource that is configured on the unlicensed spectrum and that is obtained
by the base station, and is the available PRACH resource determined by the base
25 station. However, because of an inconsistency between a location of the base station
and a location of the UE, the UE may be in a moving state. Therefore, after the base
station determines the available PRACH resource and notifies the UE of the available
PRACH resource by using the notification message, if the UE is in the moving state,
the PRACH resource sent by the foregoing base station may be unavailable in a
30 current location of the UE when the UE executes the random access procedure
according to the notification message sent by the base station; after receiving the
notification message sent by the base station and obtaining the available PRACH
resource, the UE may further determine a location of a specific to-be-used PRACH
resource in the foregoing available PRACH resource according to an actual location
26
of the UE. That is, the UE may determine, according to the information that is about
the PRACH resource and that is carried in the foregoing notification message, the
location of the available PRACH resource, that is, the location of the available
PRACH resource in the current location of the UE. After determining the location of
5 the specific available PRACH resource, the UE may send the random access code to
the base station at the location of the foregoing PRACH resource, where the foregoing
random access code is the random access code carried in the notification message.
[0080] In some feasible implementation manners, after sending the random access
code to the base station, the UE may receive, in a random access response receiving
10 window configured by the base station, the random access response message sent by
the base station, where the foregoing random access response receiving window may
be notified to the UE by using the notification message sent to the UE, that is, the
notification message sent by the foregoing base station to the UE may carry the
random access response receiving window configured by the base station. In specific
15 implementation, a scheduling command corresponding to the random access response
message sent by the base station to the UE may be scrambled by using a random
access radio network temporary identifier (Random Access-Radio Network
Temporary Identity, RA-RNTT). Before receiving the foregoing random access
response message, the UE further needs to determine a value of the foregoing
20 RA-RNTI. Specifically, the value of the foregoing RA-RNTI may be fixed in the
protocol, or may be determined according to a time frequency location and a
frequency domain location that are of the PRACH resource actually used by the UE,
or be determined by using the notification message sent by the base station; that is, the
base station may notify the UE of the value of the foregoing RA-RNTI by using the
25 foregoing notification message, and the UE may determine the value of the random
access radio network temporary identifier RA-RNTI according to protocol
pre-configuration or a time domain location and a frequency domain location that are
of the PRACH resource. After determining the value of the foregoing RA-RNTI, the
UE may decode, in the random access response receiving window by using the
30 foregoing RA-RNTI, the scheduling command corresponding to the foregoing random
access response message, and decode the random access response message according
to the foregoing scheduling command, so as to obtain the random access response
message sent by the base station. In specific implementation, a start location of the
foregoing random access response receiving window may be an Nth subframe after the
27
UE sends the random access code, or may be an Nth subframe after a specified time,
that is, the start location of the foregoing random access response receiving window
may be fixed in the protocol as the Nth subframe after the UE sends the random access
code, and the start location of the random access response receiving window is
5 notified to the UE by using the foregoing notification message, where N may be a
non-zero natural number. In this way, no matter when the UE executes the random
access procedure (sending the random access code to the base station), the random
access response receiving window may start from the Nth subframe after the UE sends
the random access code, or start from the Nth subframe after the specified time, which
10 does not cause ambiguity, and may better implement the random access procedure on
the unlicensed spectrum.
[0081] In this embodiment of the present invention, the UE may receive a
notification message sent by a base station, where the foregoing notification message
carries a random access code used by the UE to execute a random access procedure
15 and a PRACH resource that is configured on an unlicensed spectrum and that is used
by the UE to execute the random access procedure. The UE may determine, according
to the foregoing notification message, a PRACH resource used by the UE to execute
the random access procedure, send the random access code to the base station on the
resource, and further receive, in a random access response receiving window
20 configured by the base station, a random access response message sent by the base
station, which implements that the random access procedure is executed on the
unlicensed spectrum, reduces a probability of a collision in the random access
procedure on the unlicensed spectrum, and enhances user experience of the random
access procedure on the unlicensed spectrum.
25 [0082] Referring to FIG. 6, FIG. 6 is a schematic flowchart of a second
embodiment of a random access method according to an embodiment of the present
invention. The random access method described in this embodiment includes the
following steps:
[0083] S201. User equipment UE receives a notification message sent by a base
30 station.
[0084] In specific implementation, because a contention and a collision may exist
on an unlicensed spectrum resource, before instructing the UE to execute a random
access procedure, the base station cannot determine a location of a specific available
PRACH resource when the UE executes the random access procedure. Therefore, the
28
base station cannot send the available PRACH resource to the UE by using system
broadcast information, and the base station can instruct, only when the UE is required
to execute the random access procedure and by using the notification message, the UE
to execute the random access procedure and notify the UE of the available PRACH
5 resource by using the notification message.
[0085] In some feasible implementation manners, when the UE is required by the
base station to execute the random access procedure on an unlicensed spectrum, the
base station may instruct, by sending the notification message to the UE, the UE to
execute the random access procedure, and the UE may receive the notification
10 message sent by the base station, and execute the random access procedure according
to the foregoing notification message. Specifically, the foregoing notification message
may carry a random access code used by the UE to execute the random access
procedure or information about a PRACH resource that is configured on the
unlicensed spectrum and that is used by the UE to execute the random access
15 procedure. In specific implementation, the foregoing notification message may be
specifically an RRC message, an MAC message, or a PHY message. Specifically, the
random access code carried in the foregoing notification message may be a dedicated
random access code, or may be information used to instruct the UE to randomly select
a random access code. The information about the PRACH resource that is configured
20 on the unlicensed spectrum and that is used by the foregoing UE to execute the
random access procedure may include a frequency domain location of the foregoing
PRACH resource, a time domain location of the foregoing PRACH resource, or the
like, for example, a specific PRACH resource, or a subframe that is in a time domain
and in which the PRACH resource exists. The foregoing time domain information
25 may be an absolute frame number and an absolute subframe number, or a subframe
offset (for example, a sixth subframe behind a subframe of the foregoing notification
message) relative to the foregoing notification message. This embodiment of the
present invention imposes no limitation on the frequency domain location or the time
domain location of the PRACH resource. That is, when instructing, by sending the
30 notification message to the UE, the UE to execute the random access procedure, the
base station may notify the UE of an obtained specific location of the available
PRACH resource, and may further send, to the UE, the random access code used by
the UE to execute the random access. The UE may determine, according to the
PRACH resource notified in the notification message, a PRACH resource used to
29
execute the random access procedure, and send the random access code to the base
station on the foregoing determined PRACH resource.
[0086] In some feasible implementation manners, the notification message may be
sent to the UE by using a cell operating on a licensed spectrum when the base station
5 sends the notification message of executing the random access procedure to the UE.
Specifically, the notification message may be sent to the UE by using a primary cell,
or be sent to the UE by using a secondary cell. The UE may obtain, by using the
foregoing primary cell or secondary cell, the notification message sent by the base
station, where the foregoing primary cell or secondary cell may be pre-configured in a
10 protocol, or may be configured by using another message, which is not limited herein.
[0087] S202. The UE determines, according to information that is about the
PRACH resource and that is in the notification message, a location of a PRACH
resource used to execute a random access procedure.
[0088] S203. The UE listens to, according to the listening parameter, whether the
15 determined PRACH resource configured on the unlicensed spectrum is idle, or the UE
listens to, according to the listening parameter, whether the determined unlicensed
spectrum is idle.
[0089] S204. If it is detected, by means of listening, that the PRACH resource is
idle or the unlicensed spectrum is idle, send, at the determined location of the PRACH
20 resource, a random access code carried in the notification message to the base station.
[0090] S205. The UE receives a random access response message sent by the base
station, and determines, according to the random access response message, that the
random access procedure is successfully completed.
[0091] In some feasible implementation manners, after receiving the notification
25 message sent by the base station, the UE may determine, according to a configuration
parameter carried in the notification message, the PRACH resource used to execute
the random access procedure. Specifically, the configuration parameter carried in the
foregoing notification message may include the random access code used by the
foregoing UE to execute the random access procedure, the PRACH resource used by
30 the foregoing UE to execute the random access procedure, and the like; the PRACH
resource carried in the foregoing notification message is the PRACH resource that is
configured on the unlicensed spectrum and that is obtained by the base station, and is
the available PRACH resource determined by the base station. However, because of
an inconsistency between a location of the base station and a location of the UE, the
30
UE may be in a moving state. Therefore, after the base station determines the
available PRACH resource and notifies the UE of the available PRACH resource by
using the notification message, if the UE is in the moving state, the PRACH resource
sent by the foregoing base station may be unavailable in a current location of the UE
5 when the UE executes the random access procedure according to the notification
message sent by the base station; after receiving the notification message sent by the
base station and obtaining the available PRACH resource, the UE may further
determine a location of a specific to-be-used PRACH resource in the foregoing
available PRACH resource according to an actual location of the UE. Specifically, the
10 base station may send, by using the foregoing notification message, the listening
parameter that is used to listen to the PRACH resource before the UE sends the
random access code to the base station to the UE when the UE executes the random
access procedure. The PRACH resource listened to by the foregoing UE is the
PRACH resource configured on the unlicensed spectrum; that is, the UE may listen to
15 the PRACH resource sent by the base station to the UE by using the notification
message, and determine the specific available PRACH resource. The foregoing
listening parameter may include a listening time, a backoff time, a power threshold,
an energy threshold, and the like. In specific implementation, the notification message
sent by the base station to the UE may further carry a validity time for sending the
20 random access code by the UE; that is, the UE may send the random access code to
the base station on the determined available PRACH resource during the foregoing
validity time. Specifically, after determining, according to the notification message
sent by the base station, the PRACH resource used by the UE to execute the random
access procedure, the UE may listen to the foregoing PRACH resource according to
25 the foregoing listening parameter, that is, listen to whether the PRACH resource
configured on the foregoing unlicensed spectrum is idle, or the UE listens to,
according to the listening parameter, whether the determined unlicensed spectrum is
idle, and if it is detected, by means of listening, that the foregoing PRACH resource is
idle or the unlicensed spectrum is idle, the UE may send the random access code to
30 the base station on the foregoing determined PRACH resource during the foregoing
validity time for sending the random access code. In specific implementation, after
listening to, according to the foregoing listening parameter, the PRACH resource
configured on the unlicensed spectrum and determining the available PRACH
resource, the UE may further send, after a random backoff time (that is, a specified
31
time) according to the backoff time in the foregoing listening parameter, the random
access code to the base station on the foregoing available PRACH resource, where the
foregoing random access code is the random access code carried in the notification
message.
5 [0092] In some feasible implementation manners, after sending the random access
code to the base station, the UE may receive, in a random access response receiving
window configured by the base station, the random access response message sent by
the base station, where the foregoing random access response receiving window may
be notified to the UE by using the notification message sent to the UE, that is, the
10 notification message sent by the foregoing base station to the UE may carry the
random access response receiving window configured by the base station. In specific
implementation, a scheduling command corresponding to the random access response
message sent by the base station to the UE may be scrambled by using an RA-RNTI.
Before receiving the foregoing random access response message, the UE further needs
15 to determine a value of the foregoing RA-RNTI. Specifically, the value of the
foregoing RA-RNTI may be fixed in the protocol, or may be determined according to
a time frequency location and a frequency domain location that are of the PRACH
resource actually used by the UE, or be determined by using the notification message
sent by the base station; that is, the base station may notify the UE of the value of the
20 foregoing RA-RNTI by using the foregoing notification message, and the UE may
determine the value of the random access radio network temporary identifier
RA-RNTI according to protocol pre-configuration or a time domain location and a
frequency domain location that are of the PRACH resource. After determining the
value of the foregoing RA-RNTI, the UE may decode, in the random access response
25 receiving window by using the foregoing RA-RNTI, the scheduling command
corresponding to the foregoing random access response message, and decode the
random access response message according to the foregoing scheduling command, so
as to obtain the random access response message sent by the base station. In specific
implementation, a start location of the foregoing random access response receiving
30 window may be an Nth subframe after the UE sends the random access code, or may
be an Nth subframe after the specified time, that is, the start location of the foregoing
random access response receiving window may be fixed in the protocol as the Nth
subframe after the UE sends the random access code, and the start location of the
random access response receiving window is notified to the UE by using the
32
foregoing notification message, where N may be a non-zero natural number. In this
way, no matter when the UE executes the random access procedure (sending the
random access code to the base station), the random access response receiving
window may start from the Nth subframe after the UE sends the random access code,
5 or start from the Nth subframe after the specified time, which does not cause
ambiguity, and may better implement the random access procedure on the unlicensed
spectrum.
[0093] In this embodiment of the present invention, the UE may receive a
notification message sent by a base station, where the foregoing notification message
10 carries a random access code used by the UE to execute a random access procedure
and a PRACH resource that is configured on an unlicensed spectrum and that is used
by the UE to execute the random access procedure. The UE may listen to, according
to a listening parameter that is set in the notification message, the PRACH resource
that is configured on the unlicensed spectrum and that is sent by the base station,
15 determine, according to the foregoing notification message, a PRACH resource used
by the UE to execute the random access procedure, send the random access code to
the base station on the resource, and further receive, in a random access response
receiving window configured by the base station, a random access response message
sent by the base station, which implements that the random access procedure is
20 executed on the unlicensed spectrum, reduces a probability of a collision in the
random access procedure on the unlicensed spectrum, and enhances user experience
of the random access procedure on the unlicensed spectrum.
[0094] A person of ordinary skill in the art may understand that all or a part of the
processes of the methods in the embodiments may be implemented by a computer
25 program instructing relevant hardware. The program may be stored in a computer
readable storage medium. When the program runs, the processes of the methods in the
embodiments are performed. The foregoing storage medium may include: a magnetic
disk, an optical disc, a read-only memory (Read-Only Memory, ROM), or a random
access memory (Random Access Memory, RAM).
30 [0095] What is disclosed above is merely exemplary embodiments of the present
invention, and certainly is not intended to limit the protection scope of the present
invention. Therefore, equivalent variations made in accordance with the claims of the
present invention shall fall within the scope of the present invention.

I/We Claim:
1. Random access user equipment, comprising:
a receiving module, configured to receive a notification message sent by a base
5 station, wherein the notification message is used to instruct the user equipment UE to
execute a random access procedure, and the notification message carries at least one
of the following configuration parameters: a random access code used by the UE to
execute the random access procedure, or information about a physical random access
channel PRACH resource that is configured on an unlicensed spectrum and that is
10 used by the UE to execute the random access procedure;
a processing module, configured to determine, according to the configuration
parameter in the notification message received by the receiving module, a PRACH
resource used to execute the random access procedure; and
a sending module, configured to send the random access code to the base station
15 on the PRACH resource determined by the processing module; wherein
the receiving module is configured to receive a random access response message
sent by the base station, and determine, according to the random access response
message, that the random access procedure is successfully completed.
2. The user equipment according to claim 1, wherein the notification message
20 received by the receiving module may be specifically a radio resource control RRC
message, a media access control MAC message, or a physical layer PHY message.
3. The user equipment according to claim 1, wherein the random access code that
is used by the UE to execute the random access procedure and that is carried in the
notification message received by the receiving module is specifically a dedicated
25 random access code, or information used to instruct the UE to randomly select a
random access code.
4. The user equipment according to claim 1, wherein the information that is
about the PRACH resource and that is carried in the notification message received by
the receiving module comprises a frequency domain location of the PRACH resource
30 or a time domain location of the PRACH resource, wherein the PRACH resource is
configured on the unlicensed spectrum and is used by the UE to execute the random
access procedure.
34
5. The user equipment according to any one of claims 1 to 4, wherein when
determining, according to the configuration parameter in the notification message, the
PRACH resource used to execute the random access procedure, the processing
module is specifically configured to:
5 determine, according to the information that is about the PRACH resource and
that is in the notification message, a location of the PRACH resource used to execute
the random access procedure; and
the sending module is configured to send, at the determined location of the
PRACH resource, the random access code carried in the notification message to the
10 base station.
6. The user equipment according to any one of claims 1 to 4, wherein the
notification message received by the receiving module further comprises: at least one
of a listening parameter that is used to listen on the unlicensed spectrum before the
UE sends the random access code to the base station, or a validity time for sending the
15 random access code by the UE, wherein
the listening parameter comprises at least one of a listening time, a backoff time,
a power threshold, or an energy threshold.
7. The user equipment according to claim 6, wherein the processing module is
further configured to:
20 listen to, according to the listening parameter, whether the determined PRACH
resource configured on the unlicensed spectrum is idle, or listen to, according to the
listening parameter, whether the determined unlicensed spectrum is idle; and
if it is detected, by means of listening, that the PRACH resource is idle or the
unlicensed spectrum is idle, instruct the sending module to send the random access
25 code to the base station on the PRACH resource during the validity time for sending
the random access code, or instruct the sending module to send the random access
code to the base station on the PRACH resource during the validity time for sending
the random access code and after backoff is randomly performed for a specified time
according to the backoff time.
30 8. The user equipment according to claim 5 or 7, wherein the receiving module is
specifically configured to:
determine a value of a random access radio network temporary identifier
RA-RNTI according to protocol pre-configuration or a time domain location and a
frequency domain location that are of the PRACH resource; and
35
decode, by using the RA-RNTI in a random access response receiving window, a
scheduling command corresponding to the random access response message, and
decode the random access response message according to the scheduling command.
9. The user equipment according to claim 8, wherein a start location of the
random access response receiving window is specifically an N* subframe after the
UE sends the random access code; or
a start location of the random access response receiving window is specifically
an N* subframe after the specified validity time; wherein
N is a non-zero natural number.
10. A random access method, comprising:
receiving, by user equipment UE, a notification message sent by a base station,
wherein the notification message is used to instruct the UE to execute a random
access procedure, and the notification message carries at least one of the following
configuration parameters: a random access code used by the UE to execute the
random access procedure, or information about a physical random access channel
PRACH resource that is configured on an unlicensed spectrum and that is used by the
UE to execute the random access procedure;
determining, by the UE according to the configuration parameter in the
notification message, a PRACH resource used to execute the random access
procedure, and sending the random access code to the base station on the PRACH
resource; and
receiving, by the UE, a random access response message sent by the base station,
and determining, according to the random access response message, that the random
access procedure is successfully completed.
11. The method according to claim 10, wherein the notification message may be
specifically a radio resource control RRC message, a media access control MAC
message, or a physical layer PHY message.
12. The method according to claim 10, wherein the random access code used by
the UE to execute the random access procedure is specifically a dedicated random
access code, or information used to instruct the UE to randomly select a random
access code.
13. The method according to claim 10, wherein the information about the
PRACH resource that is configured on the unlicensed spectrum and that is used by the
UE to execute the random access procedure comprises a frequency domain location of
the PRACH resource or a time domain location of the PRACH resource.
14. The method according to any one of claims 10 to 13, wherein the
determining, by the UE according to the configuration parameter in the notification
message, a PRACH resource used to execute the random access procedure, and
sending the random access code to the base station on the PRACH resource
comprises:
determining, by the UE according to the information that is about the PRACH
resource and that is in the notification message, a location of the PRACH resource
used to execute the random access procedure, and sending, at the determined location
of the PRACH resource, the random access code carried in the notification message to
the base station.
15. The method according to any one of claims 10 to 13, wherein the notification
message further comprises: at least one of a listening parameter that is used to listen
on the unlicensed spectrum before the UE sends the random access code to the base
station, or a validity time for sending the random access code by the UE, wherein
the listening parameter comprises at least one of a listening time, a backoff time,
a power threshold, or an energy threshold.
16. The method according to claim 15, wherein before the sending the random
access code to the base station on the PRACH resource, the method further comprises:
listening to, by the UE according to the listening parameter, whether the
determined PRACH resource configured on the unlicensed spectrum is idle, or
listening to, by the UE according to the listening parameter, whether the determined
unlicensed spectrum is idle; and
if it is detected, by means of listening, that the PRACH resource is idle or the
unlicensed spectrum is idle, sending the random access code to the base station on the
PRACH resource during the validity time for sending the random access code, or
sending the random access code to the base station on the PRACH resource during the
validity time for sending the random access code and after backoff is randomly
performed for a specified time according to the backoff time.
17. The method according to claim 14 or 16, wherein the receiving, by the UE, a
random access response message sent by the base station comprises:
determining, by the UE, a value of a random access radio network temporary
identifier RA-RNTI according to protocol pre-configuration or a time domain location
and a frequency domain location that are of the PRACH resource; and
decoding, by the UE by using the RA-RNTI in a random access response
receiving window, a scheduling command corresponding to the random access
response message, and decoding the random access response message according to
the scheduling command.
18. The method according to claim 17, wherein a start location of the random
access response receiving window is specifically an N* sub frame after the UE sends
the random access code; or
a start location of the random access response receiving window is specifically
an N* subframe after the specified validity time; wherein
N is a non-zero natural number.