CN111194093A

CN111194093A - Random access method and equipment

Info

Publication number: CN111194093A
Application number: CN201910088145.4A
Authority: CN
Inventors: 鲍炜; 马玥; 吴昱民
Original assignee: Vivo Mobile Communication Co Ltd
Current assignee: Vivo Mobile Communication Co Ltd
Priority date: 2019-01-29
Filing date: 2019-01-29
Publication date: 2020-05-22
Anticipated expiration: 2039-01-29
Also published as: CN111194093B

Abstract

The embodiment of the invention provides a random access method and equipment, wherein the method comprises the following steps: receiving a first message, wherein the first message comprises: indicating a parameter; according to the indication parameter, the random access attempt is carried out again; wherein the indication parameters include one or more of: a first BI parameter, the first BI parameter being a BI value for a 2-step random access procedure; selection parameters of the random access procedure type. In the embodiment of the invention, RACH load concentration can be avoided, and the success probability of the random access process is improved.

Description

Random access method and equipment

Technical Field

The embodiment of the invention relates to the technical field of communication, in particular to a random access method and equipment.

Background

In order to reduce access delay in a fifth generation mobile communication (5th-generation, 5G) system, a two-step random access (2-step RACH) is introduced. When the Random Access procedure includes a two-step Random Access procedure and a four-step Random Access procedure, how the terminal avoids load concentration of a Random Access Channel (RACH) and causes Channel congestion of a Physical Random Access Channel (PRACH) to be an urgent problem to be solved.

Disclosure of Invention

An object of the embodiments of the present invention is to provide a random access method and device, which solve the problem of RACH load concentration.

According to a first aspect of the embodiments of the present invention, there is provided a random access method applied to a terminal, including:

receiving a first message, wherein the first message comprises: indicating a parameter;

according to the indication parameter, the random access attempt is carried out again;

wherein the indication parameters include one or more of: a first BI parameter, the first BI parameter being a BI value for a 2-step random access procedure; selection parameters of the random access procedure type.

According to a second aspect of the embodiments of the present invention, there is also provided a terminal, including:

a receiving module, configured to receive a first message, where the first message includes: indicating a parameter;

the processing module is used for carrying out random access attempt again according to the indication parameter;

According to a third aspect of the embodiments of the present invention, there is also provided a network device, including:

a sending module, configured to send a first message, where the first message includes: indicating a parameter;

wherein the indication parameters include one or more of: a first BI parameter, wherein the first BI parameter is a BI value of a 2-step random access process; selection parameters of the random access procedure type.

According to a fourth aspect of the embodiments of the present invention, there is also provided a communication apparatus, including: a processor, a memory and a program stored on the memory and executable on the processor, which program, when executed by the processor, performs the steps of the random access method as described above.

According to a fifth aspect of the embodiments of the present invention, there is further provided a computer-readable storage medium, characterized in that the computer-readable storage medium has stored thereon a computer program, which when executed by a processor implements the steps of the random access method as described above.

In the embodiment of the invention, RACH load concentration can be avoided, and the success probability of the random access process is improved.

Drawings

Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to refer to like parts throughout the drawings. In the drawings:

FIG. 1 is a schematic diagram of an Msg2MAC PDU;

FIG. 2 is a diagram of a MAC subheader containing a fallback indication;

FIG. 3 is a schematic diagram of a MAC subheader containing a RAPID;

fig. 4 is a schematic diagram of a MAC RAR;

fig. 5 is a schematic diagram of a two-step random access procedure;

FIG. 6 is a block diagram of a wireless communication system according to an embodiment of the present invention;

fig. 7 is a flowchart of a random access method according to an embodiment of the present invention;

fig. 8 is a second flowchart of a random access method according to an embodiment of the present invention;

FIG. 9 is a diagram of one of the MAC subheaders according to the embodiment of the invention;

FIG. 10 is a second diagram of the MAC subheader according to the second embodiment of the present invention;

FIG. 11 is a third diagram of a MAC subheader according to an embodiment of the present invention;

FIG. 12 is a fourth diagram illustrating a MAC subheader according to an embodiment of the present invention;

FIG. 13 is a fifth diagram of a MAC subheader according to an embodiment of the present invention;

FIG. 14 is a sixth schematic diagram of a MAC subheader according to an embodiment of the invention;

FIG. 15 is a schematic diagram of a padding bit according to an embodiment of the present invention;

FIG. 16 is a seventh schematic diagram of a MAC subheader according to an embodiment of the invention;

fig. 17 is a schematic diagram of a terminal according to an embodiment of the present invention;

FIG. 18 is a schematic diagram of a network device of an embodiment of the present invention;

fig. 19 is a schematic diagram of a communication device according to an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

The terms "comprises," "comprising," or any other variation thereof, in the description and claims of this application, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus. Furthermore, the use of "and/or" in the specification and claims means that at least one of the connected objects, such as a and/or B, means that three cases, a alone, B alone, and both a and B, exist.

In the embodiments of the present invention, words such as "exemplary" or "for example" are used to mean serving as examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "e.g.," an embodiment of the present invention is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, use of the word "exemplary" or "such as" is intended to present concepts related in a concrete fashion.

In order to facilitate understanding of the technical solution of the embodiment of the present invention, the following describes several technical points:

introduction about the existing random access procedure (hereinafter referred to as 4-step random access procedure):

the 4-step random access process in the 5G system is as follows:

step 1: the terminal transmits a random access preamble (preamble).

The base station (Next Generation Node B, gNB) is responsible for configuring the Preamble and the PRACH channel resources used for transmitting the resource of the Preamble, and notifies the terminal residing in the cell of the configuration result through a system message. The terminal sends a Preamble, and the base station estimates the transmission delay of the terminal according to the Preamble so as to realize uplink synchronization.

Step 2: the base station sends message 2(Msg2) (Random Access Response (RAR)).

And the network side sends a timing advance (timing advance) command to adjust the sending time of the terminal based on the transmission delay estimated in the step 1. In addition to establishing uplink synchronization, this step may also allocate uplink resources to be used in step 3 in the random access procedure for the terminal.

And step 3: the terminal sends message 3 to the base station (Msg 3).

The terminal identification information is transmitted to the network side through an uplink shared channel (UL-SCH) in a manner similar to the transmission of ordinary uplink data, and the specific content in the message 3 depends on the state of the terminal, especially whether the network side has previously known the existence of the terminal.

And 4, step 4: the base station sends message 4 to the terminal (Msg 4).

The last step, which includes the contention resolution message sent by the network side to the terminal on the downlink shared channel (DL-SCH), resolves the contention and collision caused by multiple terminals trying to access the system using the same random access resource.

And II, introduction of the Msg2 format in the 4-step random access process.

When the Network (Network, NW) detects that there is a terminal sending Preamble within a random access Occasion (RACH occupancy, RO) (i.e., a time-frequency location where the terminal sends the Preamble), it may feed back Msg 2. And the terminal determines a time window for receiving the Msg2 according to the RO time-frequency position for sending the Preamble, and tries to receive the Msg 2.

Msg2 is a Protocol Data Unit (PDU) of the MAC layer, and its format is shown in fig. 1. Msg2 may contain the following four types of information:

(1) a MAC subheader (subheader) containing a Back off Indication (BI).

See MAC sub-PDU 1 (sub-PDU 1) of fig. 1 and fig. 2. If the network side sends BI, the MAC sub PDU containing the BI is the first MAC sub PDU in the corresponding Msg 2;

(2) a MAC subheader containing RAPID.

The MAC subheader includes a Random Access Preamble Identifier (RAPID), and there is no corresponding MAC RAR, see MAC subPDU2 in fig. 1 and fig. 3.

(3) The MAC subheader containing RAPID and the MAC RAR corresponding to the subheader.

The MAC subheader contains RAPID and there is a corresponding MAC RAR, see MAC subPDU3 in fig. 1 and fig. 3. The MAC subheader is adjacent to the corresponding MAC RAR.

(4) Padding (Padding) bits.

Referring to fig. 1, if padding is needed, the padding bits are always carried after the above three types of information in Msg 2. The padding bits have no corresponding MAC subheader.

Further, the meaning of the partial fields in the MAC subheader:

(1) and (4) a T field.

The terminal can know the format of the MAC subheader by detecting the value of the T field. For example, a value of "0" for the T field indicates BI is contained; a value of "1" in the T field indicates RAPID is contained.

(2) A PAPID field.

For the MAC subheader containing RAPID, the terminal may determine whether a corresponding MAC RAR is present after the MAC subheader based on the value of RAPID, that is, the terminal knows which RAPID is present in the MAC subheader through the system broadcast message or the network configuration message of the cell, and then accompanies the corresponding MAC RAR.

(3) And E domain.

Exemplarily, the value of the E field is "1", which indicates that there are other MAC subheaders in the Msg2 after the MAC subheader; the value of the E field is "0", which indicates that after the MAC subheader, there are no other MAC subheaders in the Msg2, i.e., after the MAC subheader and the accompanying MAC RAR (if RAPID indicates its existence), the subsequent bits (bit) are padding bits.

(4) An R domain.

The R field is reserved bit. The terminal does not need to check the value of the R field.

(5) A BI domain.

And the BI domain carries parameters adopted by time domain rollback before the UE retransmits the Preamble.

And if the terminal sends the Preamble and does not receive the RAPID corresponding to the sent Preamble in the subsequent Msg2 receiving window, the terminal considers that the random access attempt fails. If the terminal receives the MAC subheader containing the BI in the Msg2 receiving window, in the subsequent random access attempt, the terminal will try Preamble sending again after the random fallback according to the BI indication. The further BI value is used for the selection of the backoff duration.

Introduction of a 2-Step random access (2-Step RACH) process:

referring to fig. 5, the steps of the 2-step random access procedure are as follows:

step 0: the network side configures configuration information of new two-step random access to the terminal, for example: the configuration information may include: and sending resource information corresponding to the request message (MsgA) and the confirmation message (MsgB).

Step 1: the terminal triggers the 2-step RACH procedure.

The terminal sends the MsgA to the network side, for example: the Preamble is transmitted through a Physical Uplink Shared Channel (PUSCH).

Step 2: and the network side sends the MsgB to the terminal.

If the terminal fails to receive the MsgB (failure means that the RAPID or contention resolution ID corresponding to the terminal's own MsgA is not received), the terminal resends Msg1 (or may resend MsgA, Msg 3).

For ease of understanding, the MsgA of the 2-step random access procedure includes main information of Msg1 and Msg3 of the 4-step random access procedure, and the MsgB of the 2-step random access procedure includes main information of Msg2 and Msg4 of the 4-step random access procedure.

In New Radio (NR), a 4-step RACH procedure has been introduced, and how to support a 2-step RACH procedure is being discussed. In future NR systems, both 2-step RACH procedures and 4-step RACH procedures will be supported. If the terminal has failed in performing the 2-step RACH procedure, it may choose to continue the RACH procedure using either the 2-step RACH procedure or the 4-step RACH procedure. In the RACH procedure, the NW may provide a Backoff Indication (BI) parameter for a terminal with RACH failure to perform random backoff, so as to avoid RACH load concentration and PRACH channel congestion.

After introducing the 2-step RACH procedure in NR, in one cell, the 2-step RACH procedure and the 4-step RACH procedure are simultaneously supported. After the 4-step RACH process fails, the terminal may choose to adopt the 2-step RACH process to continue the random access process; or after the 2-step RACH procedure fails, the random access procedure may be selected to continue with the 4-step RACH procedure. The load of RACH occupancy may be different due to the 2-step RACH procedure and the 4-step RACH procedure. Therefore, the existing BI mechanism cannot indicate the BI values of the 2-step RACH procedure and the 4-step RACH procedure at the same time. Secondly, after the current RACH fails, the terminal selects a 2-step RACH procedure or a 4-step RACH procedure, and there is no mechanism available at present, and an NW controllable mechanism needs to be designed to avoid load imbalance between the 2-step RACH procedure and the 4-step RACH procedure.

The technology described herein is not limited to a 5G system and a later-evolution communication system, and is not limited to an LTE/LTE evolution (LTE-Advanced, LTE-a) system, and may also be used for various wireless communication systems, such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single-carrier Frequency Division Multiple Access (SC-FDMA), and other systems.

The terms "system" and "network" are often used interchangeably. CDMA systems may implement Radio technologies such as CDMA2000, Universal Terrestrial Radio Access (UTRA), and so on. UTRA includes Wideband CDMA (Wideband Code Division Multiple Access, WCDMA) and other CDMA variants. TDMA systems may implement radio technologies such as Global System for Mobile communications (GSM). The OFDMA system can implement radio technologies such as Ultra Mobile Broadband (UMB), evolved-UTRA (E-UTRA)), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX)), IEEE802.20, Flash-OFDM, and the like. UTRA and E-UTRA are parts of the Universal Mobile Telecommunications System (UMTS). LTE and higher LTE (e.g., LTE-A) are new UMTS releases that use E-UTRA. UTRA, E-UTRA, UMTS, LTE-A, and GSM are described in literature from an organization named "third Generation Partnership Project" (3 GPP). CDMA2000 and UMB are described in documents from an organization named "third generation partnership project 2" (3GPP 2). The techniques described herein may be used for both the above-mentioned systems and radio technologies, as well as for other systems and radio technologies.

Embodiments of the present invention are described below with reference to the accompanying drawings. The random access method and the equipment provided by the embodiment of the invention can be applied to a wireless communication system. Fig. 6 is a block diagram of a wireless communication system according to an embodiment of the present invention. As shown in fig. 6, the wireless communication system may include: network device 60 and a terminal, denoted User Equipment (UE) 61, UE61 may communicate (transmit signaling or transmit data) with network device 60. In practical applications, the connections between the above devices may be wireless connections, and fig. 6 illustrates solid lines for convenience and intuition of the connection relationships between the devices. It should be noted that the communication system may include a plurality of UEs 61, and the network device 60 may communicate with a plurality of UEs 61.

The terminal provided by the embodiment of the invention can be a Mobile phone, a tablet computer, a notebook computer, an Ultra-Mobile personal computer (UMPC), a netbook or a Personal Digital Assistant (PDA), a Mobile Internet Device (MID), a wearable Device (wearable Device) or a vehicle-mounted Device, and the like.

The network device 60 provided in the embodiment of the present invention may be a base station, which may be a commonly used base station, an evolved node base station (eNB), or a network device in a 5G system (e.g., a next generation base station (gNB) or a Transmission and Reception Point (TRP)).

It should be noted that, in the embodiment of the present invention, the recording may be performed by directly recording the acquired information, or may be performed by recording other information corresponding to the acquired information, taking the record a value as an example, and includes one of the following:

(1) directly recording the A value obtained from the message;

(2) obtaining the B value from the message, obtaining the a value corresponding to the B value based on a preset manner, and recording the a value, where the preset manner may be to search for a corresponding relationship, and certainly is not limited thereto.

It should be noted that all the drawings in the specification are schematic diagrams. The figures merely indicate that there are required related domains, and the meaning of the related domains. But the name, length, relative position of the relevant fields may differ from the schematic.

It should be noted that the 2-step random access procedure in the embodiment of the present invention is a contention-based 2-step random access procedure.

Referring to fig. 7, an embodiment of the present invention provides a random access method, where an execution main body of the method may be a terminal, and specifically includes step 701 and step 702.

Step 701: receiving a first message, wherein the first message comprises: indicating a parameter;

for example, the indication parameter is a parameter required for a subsequent random access attempt, and the indication parameter may indicate that the terminal re-attempts random access preamble transmission.

The first message is used for responding to a random access request in a random access process, and further, the first message may be Msg2 or MsgB.

Step 702: according to the indication parameters, the random access attempt is carried out again;

it can be understood that, the re-performing the random access attempt refers to the UE re-performing the random access attempt when the number of Msg1 or MsgA transmissions does not reach the preset maximum number, and may include: the UE resends Msg1 or MsgA.

Wherein the indication parameters may include one or more of: a first BI parameter, the first BI parameter being a BI value for a 2-step random access procedure; a selection parameter of a random access procedure type (or may also be referred to as a RACH procedure selection factor, or RACH procedure selection parameter).

Alternatively, the meaning of the selection parameter may be any one of the following:

(1) indicating the probability of subsequently initiating a 2-step random access process;

(2) indicating the probability of subsequently initiating a 4-step random access process;

(3) indicating the probability that the subsequent random access procedure type continues to use the previous random access procedure type;

(4) indicating the probability of the subsequent random access procedure type and further the previous random access procedure type.

Further, the random access procedure type includes one or more of: a 2-step random access procedure and a 4-step random access procedure.

In this embodiment of the present invention, optionally, the indicating parameter may further include: a second BI parameter, the second BI parameter being a BI value for a 4-step random access procedure.

In this embodiment of the present invention, a manner of carrying the indication parameter by the first message includes:

first, the indication parameter is carried in the padding bit field of the first message, and for an exemplary description, reference may be made to mode 4 of scenario one and mode 2 of scenario two described below. For compatibility with terminals (e.g., 3GPP Rel-15 UEs) to which embodiments of the present invention are not applied, the indication parameter may be carried in the Msg2 padding bit field specified in the R15 protocol, for example. An indication parameter is included in a padding bit field indicating Msg2 in a MAC subheader containing a BI value.

Further, the MAC subheader of the first message includes: first indication information indicating that the indication parameter is included in a padding bit field of the first message.

Further, the padding bit field of the first message refers to a first part in the first message, and the first part is a part understood as the padding bit field by a terminal (e.g. 3GPP Rel-15UE) to which the embodiment of the present invention is not applied.

Second, the indication parameter is carried in the MAC RAR of the first message, and for an exemplary description, reference may be made to a mode 5 of a scenario one and a mode 3 of a scenario two described below.

For compatibility with a terminal (e.g. 3GPP Rel-15UE) to which the embodiment of the present invention is not applied, for example, the indication parameter may be carried in a MAC RAR specified in the R15 protocol (a Preamble needs to be reserved, and the MAC RAR needs to be redefined). The reserved Preamble number is indicated in the RACH configuration.

And thirdly, the first BI parameter or the selection parameter is carried in the reserved bits of the MAC subheader of the first message, and the MAC subheader further includes: the second BI parameter, exemplary description, may refer to scenario one, scenario 3, and scenario two, scenario 4, described below. For compatibility with a terminal (e.g., 3GPP Rel-15UE) to which the embodiments of the present invention are not applied, the indication parameter may be carried in a reserved bit field in a MAC subheader containing BI specified in the R15 protocol, for example.

Fourth, the indication parameter is carried in the first message according to a mode of being incompatible with the 3GPP R15 protocol, and for an exemplary description, reference may be made to other modes of the scenario one and scenario two described below. For example:

(1) the first message includes: a first MAC subheader and a second MAC subheader, wherein the first MAC subheader comprises: the first BI parameter, the second MAC subheader, comprising: the second BI parameter.

Further, the position of the first MAC subheader precedes the position of the second MAC subheader, or the position of the second MAC subheader precedes the position of the first MAC subheader.

Or, the first MAC subheader is carried at a header of a media access control protocol data unit (MAC PDU) of the first message, and the second MAC subheader is carried at a tail of the MAC PDU;

or, the first MAC subheader is carried at a tail of a media access control protocol data unit (MAC PDU) of the first message, and the second MAC subheader is carried at a header of the MAC PDU.

The exemplary description related to (1) above may be referred to as mode 1 of scenario one described below.

(2) The first message includes: a third MAC subheader, wherein the third MAC subheader comprises: the BI value represents the first BI parameter when the second indication information is a first value, and the BI value represents the second BI parameter when the second indication information is a second value.

The exemplary description related to (2) above may be referred to as mode 2 of scenario one described below.

(3) The first message includes: a fourth MAC subheader, wherein the fourth MAC subheader comprises: and third indication information, wherein when the third indication information is the first value, the fourth MAC subheader further includes: the selection parameter.

Further, when the third indication information is a second value, it indicates that the fourth MAC subheader further includes: the first BI parameter or the second BI parameter.

The exemplary description related to (3) above may be referred to as mode 1 of scenario two described below.

(4) The first message includes: a fifth MAC subheader, the fifth MAC subheader comprising: fourth indication information, where the fourth indication information is used to indicate that the fifth MAC subheader further includes any one of the following items: the first BI parameter, the second BI parameter, and a selection parameter.

The exemplary description related to (4) above may be referred to as mode 5 of scenario two described below.

In the embodiment of the present invention, optionally, the terminal may perform the random access attempt according to the following manner:

and in the mode A, the terminal selects and uses the 2-step random access process or the 4-step random access process to perform random access attempt again according to the selection parameters in the indication parameters.

Mode B, if the terminal determines that the subsequent random access type is a 2-step random access process, carrying out rollback according to a first BI parameter in the indication parameters, and then carrying out a random access attempt; or if the terminal determines that the subsequent random access type is a 4-step random access process, performing backoff according to a second BI parameter in the indication parameters, and then performing a random access attempt.

Specifically, if the terminal selects to initiate the 2-step random access process, the terminal backs down according to the recorded first BI parameters, and if the Msg2 or the MsgB received by the terminal has the first BI parameters, the terminal records the first BI parameters; otherwise, the first BI parameter record is 0; alternatively, the first and second electrodes may be,

if the terminal selects to initiate the 4-step random access process, the terminal backs down according to the recorded second BI parameters, and if the Msg2 or the MsgB received by the terminal has the second BI parameters, the terminal records the second BI parameters; otherwise, the second BI parameter is recorded as 0.

Wherein, the mode a and the mode B are independent processes, that is, the "selection parameter" is a parameter that may not be notified in the Msg2 or the MsgB, and without the selection parameter, the terminal may decide the random access procedure type on its own basis based on the implementation and execute the mode B.

Referring to fig. 8, an embodiment of the present invention further provides a random access method, where an execution subject of the method is a network device, and the method includes the specific steps of: step 801.

Step 801: sending a first message, wherein the first message comprises: indicating a parameter;

wherein the indication parameters include one or more of: a first fallback indication BI parameter, wherein the first BI parameter is a BI value of a 2-step random access process; selection parameters of the random access procedure type.

It can be understood that the 2-step random access procedure of the embodiment of the present invention is a contention-based 2-step random access procedure.

first, the indication parameter is carried in the padding bit field of the first message, and for an exemplary description, reference may be made to mode 4 of scenario one and mode 2 of scenario two described below.

Further, the padding bit field of the first message refers to a first part in the first message, and the first part is a part which is understood as the padding bit field by a terminal (e.g. 3GPP Rel-15UE) to which the embodiment of the present invention is not applied.

And thirdly, the first BI parameter or the selection parameter is carried in the reserved bits of the MAC subheader of the first message, and the MAC subheader further includes: the second BI parameter, exemplary description, may refer to scenario one, scenario 3, and scenario two, scenario 4, described below.

And fourthly, carrying the indication parameter in the first message according to a mode of incompatible with a 3GPP R15 protocol.

For example:

Or, the first MAC subheader is carried at the head of the MAC PDU of the first message, and the second MAC subheader is carried at the tail of the MAC PDU;

or, the first MAC subheader is carried at the tail of the MAC PDU of the first message, and the second MAC subheader is carried at the head of the MAC PDU.

(4) The first message includes: a fifth MAC subheader, the fifth MAC subheader comprising: fourth indication information, where the fourth indication information is used to indicate that the fifth MAC subheader further includes any one of the following items: the first BI parameter, the second BI parameter, and the selection parameter.

In the embodiment of the present invention, in the second step of the random access procedure, the first BI parameter may be carried. The first BI parameter is used to indicate a BI value that the UE needs to adopt in the 2-step RACH. And/or, in the second step of the random access procedure, a selection parameter of the type of the random access procedure may be carried, and the selection parameter is used for the UE to subsequently select the RACH procedure for use. It should be noted that, in the following scenario one and scenario two, only 3GPP Rel-15UE is taken as an example for description, and the implementation manner of other terminals to which the embodiment of the present invention is not applied is similar, and will not be described herein again.

Scene one: the first and second BI parameters are carried in Msg2 or MsgB of the RACH procedure.

1, UE initiates a 2-step random access process or a 4-step random access process and sends Msg1 or MsgA;

the UE attempts to receive Msg2 or MsgB within the Msg2 or MsgB window, and if there are a first BI parameter and a second BI parameter in the received Msg2 or MsgB, the UE records the first BI parameter and the second BI parameter, wherein: the first BI parameter is a value of a BI for the 2-step random access procedure; the second BI is used for the BI value of the 4-step random access procedure; if the first and/or second BI parameters do not exist in the received Msg2 or MsgB, the UE alters the recorded BI value (e.g., records the recorded value as 0) so that a random backoff is not required.

3. If the UE RACH attempt fails (e.g., not received at the expected time: Msg2 or MsgB containing the corresponding RAPID or MsgB containing the corresponding UE ID or Msg4 containing the corresponding terminal contention resolution identity (UE contention resolution ID)), and the maximum number of times is not reached, the UE performs any of the following:

a. if the UE selects to try again by using the 2-step random access process, the UE tries to access again after applying the recorded first BI parameter to carry out random fallback;

b. and if the UE chooses to try again by using the 4-step random access process, the UE tries to access again after applying the recorded second BI parameters to carry out random fallback.

In scenario one, the first BI parameter and the second BI parameter are carried in the following five ways (way 1 to way 5).

Mode 1: the MAC subheader carrying the BI value can reuse the existing format, see fig. 9.

Further, in order to distinguish between the first BI parameter and the second BI parameter, it may be specified that in Msg2 or MsgB, the first occurring BI value is the first BI parameter, and the second occurring BI value is the second BI parameter; or, conversely, the first occurring BI value is the second BI parameter and the second occurring BI value is the second BI.

Alternatively, in the MAC PDU of Msg2 or MsgB, the first position is a first BI parameter (e.g., the length of the MAC subheader (subheader) carrying the BI value is N bytes), the first position refers to the first Nbyte in the MAC PDU), and the last position is a second BI parameter (e.g., the length of the MAC subheader carrying the BI value is Nbyte, and the last position refers to the last Nbyte in the MAC PDU).

Mode 2: the MAC subheader carrying the BI value may adopt a new format in which a new type (type) field is introduced, for example, see the T2 field in fig. 10.

And when the T2 field takes the first value, the BI value contained in the MAC sub-header is represented as a first BI parameter, and when the T2 field takes the second value, the BI contained in the MAC sub-header is represented as a second BI parameter.

It is to be understood that the specific name of this type of domain is not limited in the embodiments of the present invention.

Mode 3: the two first and second BI parameters are carried in one MAC subheader.

Illustratively, referring to fig. 11, the BI value applied to the 2-step RACH may be carried in the BI2 field. Since the UE of R15 (not supporting 2-step RACH) considers 2bit of BI2 domain as reserved bit (rabit), the UE will not decode the BI2 domain. Whereas a UE supporting 2-step RACH needs to decode the BI2 field.

Therefore, this approach has no impact on 3GPP Rel-15 UEs (or UEs that do not support 2-step RACH).

It is to be understood that a specific name of the domain carrying the BI value of the 2-step RACH is not limited in the embodiment of the present invention.

Mode 4: the MAC subheader carrying the BI value is in a new format.

Illustratively, referring to fig. 12, the E2 field is introduced in the MAC subheader. The E2 field indicates that in the padding bit field of Msg2, the first BI parameter (BI value for 2-step RACH) is contained. It is to be understood that a specific name indicating a field containing the first BI parameter in the padding bit field of the Msg2 is not limited in the embodiment of the present invention.

Mode 4 has better compatibility. When 2-step RACH and 4-step RACH are simultaneously supported in one cell, and there are cases of 3GPP Rel-15 and Rel-16 UEs:

(1) for 3GPP Rel-15 UEs, which support only 4-step RACH, they do not decode the E2 domain. The UE is unaware that the padding bit field exists for the first BI parameter.

(2) For Rel-16's UE, which supports 2-step RACH and 4-step RACH, the E2 domain may be identified and the second BI parameters decoded from the BI domain.

Since the 3GPP Rel-15UE does not decode the padding bit field, this approach 4 has no impact on the UE of R15. Through the E2 field, the NW indicates that the UE of Rel-16 has the first BI parameter in the padding bit field, and thus, the UE of Rel-16 can obtain the BI value of the 2-step RACH dedicated to the UE of Rel-16 in the padding bit field.

In this manner 4, the MAC subheader containing the new BI field may be placed at a specific position of the padding bit field, for example, a start position (such as the starting Nbyte) or an end position (such as the last Nbyte), assuming that the MAC subheader containing the BI field is Nbyte.

Mode 5: the new BI values are carried in the MAC RAR.

The network reserves a Preamble, which is not used for random access. Thus, the RAPID corresponding to the Preamble (e.g., RAPID 63) can be used for other purposes.

At most, 64 corresponding preambles can exist for one RO, each Preamble is corresponding to one RAPID, and the RAPID length is 6 bits.

For example, when a MAC subheader containing RAPID occurs, if RAPID is 63, its subsequent 7 bytes may adopt a format different from the MAC RAR. For example, a first BI parameter may be carried.

In the system, if a RAPID is detected to be 63 in Msg2, the 3GPP Rel-15UE will skip the 7 bytes following the MAC subheader (because the UE will assume that the 7 bytes are RARs of other UEs (the RAPID corresponding to the sent Preamble is 63).

However, since the network keeps the Preamble (no UE is allowed to use), the 7byte corresponding to the RAR can be redefined.

Further, preferably, the first BI parameter may be carried in a MAC subheader, and a format of the MAC subheader may be consistent with an existing format.

In the MAC subheader, the meaning of the E field may be redefined, indicating whether the MAC subheader is the last MAC subheader within the redefined 7byte area.

Scene two: RACH type selection parameters (hereinafter referred to as selection parameters) are carried in the Msg2 or MsgB of the RACH procedure.

1, UE initiates a2 or 4-step random access process and sends Msg1 or MsgA;

the UE is in the Msg2 or MsgB window, if the selection parameter exists in the received Msg2 or MsgB, the UE saves the selection parameter;

as an optimized implementation: if no selection parameter exists in the received Msg2 or MsgB, the UE changes the value of this selection parameter of the record (e.g. sets the record value to 0), indicating one of the following meanings:

(1) continuing to select the current RACH type;

(2) disallowing selection of the current RACH type;

(3) how the RACH type is selected is decided by the UE, i.e. how the RACH type is selected is left to the UE implementation.

3. If the UE RACH attempt has not reached the maximum number of times, and the UE chooses to use the 2-step RACH or the 4-step RACH for subsequent RACH attempts based on the saved selection parameters.

An alternative mechanism for applying the selection parameter is as follows:

the selection parameter stored by the UE may be a value a, the UE generates a value B by itself (for example, randomly generates the value B within a value range), and then compares the magnitudes of a and B: if A is greater than or equal to B, adopting a first RACH flow; otherwise, a second RACH procedure is used.

In the second scenario, the following five modes (mode 1 to mode 5) are used to carry the selected parameters.

Mode 1: the MAC subheader with the selection parameters can be in a new format, introducing a new type field, see the T1 field of fig. 13.

For example, the value of the T field is 0, which indicates that the MAC subheader does not include RAPID.

Optionally, the value of the T1 field is the first value, which indicates that the MAC subheader contains the selection parameter; the value of the T1 field is a second value, which indicates that the MAC subheader contains a BI field.

Mode 2: the MAC subheader with the selection parameters takes a new format and introduces a new field, see for example the E2 field of fig. 14.

The E2 field indicates that the padding bit field contains an indication parameter. Upon receiving this information, the UE of Rel-16 knows that the padding bit field needs to be decoded.

It is to be understood that a specific name indicating a field containing a selection parameter in the Msg2 or MsgB pad bit field is not limited in the embodiment of the present invention.

In the pad bit field, one possible format is shown in fig. 15.

In fig. 15, the E field indicates whether the present MAC subheader is the last MAC subheader in the padding bit field;

the T field indicates whether the BI value or the selection parameter is carried in the MAC subheader.

Mode 2 can carry specific information visible to the UE supporting only 2-step RACH in the padding bit field specified by the R15 protocol, avoiding the impact on 3GPP Rel-15 UEs.

Mode 3: the selection parameters are carried in the MAC RAR.

In mode 3, the network reserves a Preamble, which is not used for random access. Thus, the RAPID corresponding to the Preamble (e.g., RAPID 63) can be used for other purposes.

For example, when a MAC subheader containing RAPID occurs, if RAPID is 63, its subsequent 7 bytes may adopt a different format than the existing MAC RAR. For example, the selection parameters may be carried in the MAC RAR.

Preferably, the selection parameters may be carried in a MAC subheader. In the MAC subheader, the meaning of the E field indicating whether the MAC subheader is the last MAC subheader within the redefined 7byte area is redefined.

In the MAC subheader, there is a type indication field, wherein a first value of the type indication field indicates that the MAC subheader contains the selection parameter.

Mode 4: the BI values and the selection parameters are carried in a MAC subheader.

Referring to fig. 16, the selection parameters may be carried in the Factor domain. Since 3GPP Rel-15UE (does not support 2-step RACH), 2bit of the Factor domain is considered as reserved bit (Rbit), so the UE will not decode the Factor domain. And a UE supporting 2-step RACH needs to decode the Factor domain.

Therefore, this approach 4 has no impact on 3GPP Rel-15 UEs (or UEs that do not support 2-step RACH).

Mode 5: a BI value and selection parameter joint design mode comprises the following steps:

the MAC subheader contains the T field: for indicating whether RAPID is contained in the MAC subheader:

for the case where RAPID is not included, there is a T1 field in the MAC subheader indicating that the MAC subheader includes the following fields:

(1) a first BI parameter;

(2) a second BI parameter;

(3) parameters are selected.

For example: the length of the T1 domain is 2bit, and the value in 4 is supported.

When the T1 field takes on the first value: indicating that the MAC subheader contains the first BI parameter (BI value for 2-step RACH);

when the T1 field takes the second value: indicates that the MAC subheader contains the second BI parameter (BI value for 4-step RACH);

when the T1 field takes the third value: indicating that the MAC subheader contains selection parameters for RACH type selection.

Illustratively, the T1 field may use reserved bits (rabit), although not limited thereto.

The embodiment of the invention also provides a terminal, and as the principle of solving the problem of the terminal is similar to the random access method in the embodiment of the invention, the implementation of the terminal can refer to the implementation of the method, and repeated parts are not repeated.

Referring to fig. 17, an embodiment of the present invention further provides a terminal, where the terminal 1700 includes:

a receiving module 1701, configured to receive a first message, where the first message includes: indicating a parameter;

a processing module 1702, configured to perform a random access attempt again according to the indication parameter;

In this embodiment of the present invention, optionally, the indicating parameter further includes: a second BI parameter, the second BI parameter being a BI value for a 4-step random access procedure.

In this embodiment of the present invention, optionally, the indication parameter is carried in a padding bit field of the first message.

In this embodiment of the present invention, optionally, the MAC subheader of the first message includes: first indication information indicating that the indication parameter is included in a padding bit field of the first message.

In this embodiment of the present invention, optionally, the padding bit field of the first message refers to a first part in the first message, where the first part is a part that a terminal (e.g., 3GPP Rel-15UE) not applying the embodiment of the present invention understands as the padding bit field.

In this embodiment of the present invention, optionally, the indication parameter is carried in a medium access control random access response, MAC RAR, of the first message.

In this embodiment of the present invention, optionally, the first BI parameter or the selection parameter is carried in a reserved bit of a MAC subheader of the first message, where the MAC subheader further includes: the second BI parameter.

In this embodiment of the present invention, optionally, the processing module 1702 is further configured to: and according to the selection parameters in the indication parameters, selecting to use a 2-step random access process or a 4-step random access process to perform random access attempt again.

In this embodiment of the present invention, optionally, the processing module 1702 is further configured to: performing any one of:

if the terminal determines that the subsequent random access type is a 2-step random access process, carrying out backspacing according to a first BI parameter in the indication parameters, and then carrying out a random access attempt;

and if the terminal determines that the subsequent random access type is a 4-step random access process, carrying out backspacing according to a second BI parameter in the indication parameters, and then carrying out a random access attempt.

In this embodiment of the present invention, optionally, the first message includes: a first MAC subheader and a second MAC subheader, wherein the first MAC subheader comprises: the first BI parameter, the second MAC subheader, comprising: the second BI parameter.

In this embodiment of the present invention, optionally, the position of the first MAC subheader precedes the position of the second MAC subheader, or the position of the second MAC subheader precedes the position of the first MAC subheader.

In this embodiment of the present invention, optionally, the first MAC subheader is carried at a header of a MAC PDU of the first message, and the second MAC subheader is carried at a tail of the MAC PDU; or, the first MAC subheader is carried at the tail of the MAC PDU of the first message, and the second MAC subheader is carried at the head of the MAC PDU.

In this embodiment of the present invention, optionally, the first message includes: a third MAC subheader, wherein the third MAC subheader comprises: the BI value represents the first BI parameter when the second indication information is a first value, and the BI value represents the second BI parameter when the second indication information is a second value.

In this embodiment of the present invention, optionally, the first message includes: a fourth MAC subheader, wherein the fourth MAC subheader comprises: third indication information, wherein when the third indication information is a first value, the fourth MAC subheader further includes: the selection parameter.

In this embodiment of the present invention, optionally, when the third indication information is a second value, it indicates that the fourth MAC subheader further includes: the first BI parameter or the second BI parameter.

In this embodiment of the present invention, optionally, the first message includes: a fifth MAC subheader, the fifth MAC subheader comprising: fourth indication information, where the fourth indication information is used to indicate that the fifth MAC subheader further includes any one of the following items: the first BI parameter, the second BI parameter, and the selection parameter.

The terminal provided by the embodiment of the present invention can execute the above method embodiment, and the implementation principle and technical effect are similar, which are not described herein again.

The embodiment of the present invention further provides a network device, and as the principle of solving the problem of the network device is similar to the random access method in the embodiment of the present invention, the implementation of the network device may refer to the implementation of the method, and the repetition part is not described again.

Referring to fig. 18, an embodiment of the present invention further provides a network device, where the network device 1800 includes:

a sending module 1801, configured to send a first message, where the first message includes: indicating a parameter;

In this embodiment of the present invention, optionally, the indication parameter is carried in a MAC RAR of the first message.

In this embodiment of the present invention, optionally, the first message includes a first MAC subheader and a second MAC subheader, where the first MAC subheader includes: the first BI parameter, the second MAC subheader, comprising: the second BI parameter.

The network device provided by the embodiment of the present invention may execute the above method embodiment, and the implementation principle and technical effect are similar, which are not described herein again.

Referring to fig. 19, fig. 19 is a structural diagram of a communication device applied in the embodiment of the present invention, and as shown in fig. 19, a communication device 1900 includes: a processor 1901, a transceiver 1902, a memory 1903, and a bus interface, wherein:

in one embodiment of the invention, the communication device 1900 further comprises: a program stored on the memory 1903 and executable on the processor 1901, the program when executed by the processor 1901 performing the steps of: receiving a first message, wherein the first message comprises: indicating a parameter; performing a random access attempt according to the indication parameter; wherein the indication parameters include one or more of: a first BI parameter, the first BI parameter being a BI value for a 2-step random access procedure; selection parameters of the random access procedure type.

In another embodiment of the present invention, the communication device 1900 further comprises: a program stored on the memory 1903 and executable on the processor 1901, the program when executed by the processor 1901 performing the steps of: sending a first message, wherein the first message comprises: indicating a parameter; wherein the indication parameters include one or more of: a first BI parameter, wherein the first BI parameter is a BI value of a 2-step random access process; selection parameters of the random access procedure type.

In FIG. 19, the bus architecture may include any number of interconnected buses and bridges, with one or more processors, represented by processor 1901, and various circuits, represented by memory 1903, being linked together. The bus architecture may also link together various other circuits such as peripherals, voltage regulators, power management circuits, and the like, which are well known in the art, and therefore, will not be described any further herein. The bus interface provides an interface. The transceiver 1902 may be a plurality of elements including a transmitter and a receiver providing a means for communicating with various other apparatus over a transmission medium.

The processor 1901 is responsible for managing the bus architecture and general processing, and the memory 1903 may store data used by the processor 1901 in performing operations.

The communication device provided by the embodiment of the present invention may execute the above method embodiment, and the implementation principle and technical effect are similar, which are not described herein again.

The steps of a method or algorithm described in connection with the disclosure herein may be embodied in hardware or may be embodied in software instructions executed by a processor. The software instructions may consist of corresponding software modules that may be stored in RAM, flash memory, ROM, EPROM, EEPROM, registers, hard disk, a removable hard disk, a compact disk, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. Of course, the storage medium may also be integral to the processor. The processor and the storage medium may reside in an ASIC. In addition, the ASIC may be carried in a core network interface device. Of course, the processor and the storage medium may reside as discrete components in a core network interface device.

Those skilled in the art will recognize that, in one or more of the examples described above, the functions described in this invention may be implemented in hardware, software, firmware, or any combination thereof. When implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer.

The above-mentioned embodiments, objects, technical solutions and advantages of the present invention are further described in detail, it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made on the basis of the technical solutions of the present invention should be included in the scope of the present invention.

As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, embodiments of the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, embodiments of the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

Embodiments of the present invention are described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

It will be apparent to those skilled in the art that various changes and modifications may be made in the embodiments of the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to encompass such modifications and variations.

Claims

1. A random access method applied to a terminal is characterized by comprising the following steps:

wherein the indication parameters include one or more of: a first fallback indication (BI) parameter, wherein the first BI parameter is a BI value used for a 2-step random access process; selection parameters of the random access procedure type.

2. The method of claim 1, wherein the indicating parameters further comprise: a second BI parameter, the second BI parameter being a BI value for a 4-step random access procedure.

3. The method of claim 1, wherein the indication parameter is carried in a padding bit field of the first message.

4. The method of claim 3, wherein the MAC subheader of the first message comprises: first indication information indicating that the indication parameter is included in a padding bit field of the first message.

5. The method according to claim 3 or 4, wherein the padding bit field of the first message refers to a first part in the first message, and the first part is a part understood as the padding bit field by a terminal of Rel-15.

6. The method according to claim 1, characterized in that said indication parameter is carried in a medium access control random access response, MAC RAR, of said first message.

7. The method of claim 2, wherein the first BI parameter or selection parameter is carried in reserved bits of a MAC subheader of the first message, the MAC subheader further comprising: the second BI parameter.

8. The method of claim 1, wherein the performing a random access attempt according to the indication parameter comprises:

and selecting 2-step random access process or 4-step random access process to attempt random access according to the selected parameters in the indication parameters.

9. The method according to claim 2 or 8, wherein the re-performing the random access attempt according to the indication parameter comprises any one of the following:

10. The method of claim 2, wherein the first message comprises: a first MAC subheader and a second MAC subheader, wherein the first MAC subheader comprises: the first BI parameter, the second MAC subheader, comprising: the second BI parameter.

11. The method of claim 10, wherein the position of the first MAC subheader precedes the position of the second MAC subheader, or wherein the position of the second MAC subheader precedes the position of the first MAC subheader.

12. The method of claim 10, wherein the first MAC subheader is carried at a head of a media access control protocol data unit, MAC PDU, of the first message, and wherein the second MAC subheader is carried at a tail of the MAC PDU; or, the first MAC subheader is carried at the tail of the MAC PDU of the first message, and the second MAC subheader is carried at the head of the MAC PDU.

13. The method of claim 2, wherein the first message comprises: a third MAC subheader, wherein the third MAC subheader comprises: the BI value represents the first BI parameter when the second indication information is a first value, and the BI value represents the second BI parameter when the second indication information is a second value.

14. The method of claim 1, wherein the first message comprises: a fourth MAC subheader, wherein the fourth MAC subheader comprises: third indication information, wherein when the third indication information is a first value, the fourth MAC subheader further includes: the selection parameter.

15. The method of claim 14, wherein when the third indication information is a second value, indicating that the fourth MAC subheader further includes: the first BI parameter or the second BI parameter.

16. The method of claim 2, wherein the first message comprises: a fifth MAC subheader, the fifth MAC subheader comprising: fourth indication information, where the fourth indication information is used to indicate that the fifth MAC subheader further includes any one of the following items: the first BI parameter, the second BI parameter, and the selection parameter.

17. A random access method is applied to network equipment, and is characterized by comprising the following steps:

sending a first message, wherein the first message comprises: indicating a parameter;

18. The method of claim 17, wherein the indicating parameters further comprise: a second BI parameter, the second BI parameter being a BI value for a 4-step random access procedure.

19. The method of claim 17, wherein the indication parameter is carried in a padding bit field of the first message.

20. The method of claim 19, wherein the MAC subheader of the first message comprises: first indication information indicating that the indication parameter is included in a padding bit field of the first message.

21. The method according to claim 19 or 20, wherein the padding bit field of the first message refers to a first part in the first message, and the first part is a part understood by terminals of Rel-15 as the padding bit field.

22. The method of claim 17, wherein the indication parameter is carried in a MACRAR of the first message.

23. The method of claim 18, wherein the first BI parameter or selection parameter is carried in reserved bits of a MAC subheader of the first message, wherein the MAC subheader further comprises: the second BI parameter.

24. The method of claim 18, wherein the first message comprises a first MAC subheader and a second MAC subheader, and wherein the first MAC subheader comprises: the first BI parameter, the second MAC subheader, comprising: the second BI parameter.

25. The method of claim 24, wherein the position of the first MAC subheader precedes the position of the second MAC subheader, or wherein the position of the second MAC subheader precedes the position of the first MAC subheader.

26. The method of claim 24, wherein the first MAC subheader is carried at a header of a MAC PDU of the first message, and wherein the second MAC subheader is carried at a tail of the MAC PDU; or; the first MAC subheader is carried at the tail part of the MAC PDU of the first message, and the second MAC subheader is carried at the head part of the MAC PDU.

27. The method of claim 18, wherein the first message comprises: a third MAC subheader, wherein the third MAC subheader comprises: the BI value represents the first BI parameter when the second indication information is a first value, and the BI value represents the second BI parameter when the second indication information is a second value.

28. The method of claim 18, wherein the first message comprises: a fourth MAC subheader, wherein the fourth MAC subheader comprises: third indication information, wherein when the third indication information is a first value, the fourth MAC subheader further includes: the selection parameter.

29. The method of claim 28, wherein when the third indication information is a second value, indicating that the fourth MAC subheader further comprises: the first BI parameter or the second BI parameter.

30. The method of claim 18, wherein the first message comprises: a fifth MAC subheader, the fifth MAC subheader comprising: fourth indication information, where the fourth indication information is used to indicate that the fifth MAC subheader further includes any one of the following items: the first BI parameter, the second BI parameter, and the selection parameter.

31. A terminal, comprising:

32. A network device, comprising:

33. A communication device, comprising: a processor, a memory and a program stored on the memory and executable on the processor, which program, when executed by the processor, performs the steps of the random access method according to any one of claims 1 to 16; or, the steps of a random access method according to any of claims 17 to 30.

34. A computer-readable storage medium, characterized in that a computer program is stored thereon, which computer program, when being executed by a processor, carries out the steps of the random access method according to any one of claims 1 to 16; or, the steps of a random access method according to any of claims 17 to 30.