WO2012083739A1

WO2012083739A1 - Random access method and terminal

Info

Publication number: WO2012083739A1
Application number: PCT/CN2011/080006
Authority: WO
Inventors: 艾建勋; 邓云
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-12-22
Filing date: 2011-09-22
Publication date: 2012-06-28
Also published as: CN102548012A; CN102548012B

Abstract

Disclosed in the present invention is a random access method, after the terminal detects a failure of random access, the random access is initiated again after waiting for a set time. Also disclosed correspondingly in the present invention is a terminal. According to the present invention, after the terminal fails to random access, the random access is initiated again after waiting for a period of time, so as to avoid the wireless resource shortage which is caused by the terminal continually initiating random access again in the case of wireless resource overload, and the application of the present invention can average the terminal amount that accessing the network at a unit of time, thereby improving the success rate of random access.

Description

Random access method and terminal

The present invention relates to the field of mobile communications, and in particular, to a random access method and a terminal. Background technique

Human to Human (H2H) refers to the communication between people through the operation of the device. The existing wireless communication technology is developed based on H2H communication, and machine to machine (Μ2Μ) is broadly defined. The definition is based on the intelligent interaction of the machine terminal, and the networked application and service. It is based on the intelligent machine terminal, and uses multiple communication methods as access means to provide customers with information solutions to meet customer requirements. Information needs for monitoring, command and dispatch, data collection and measurement.

The development of wireless technology is an important factor in the development of the market. It breaks through the space-time restrictions and geographical barriers of traditional communication methods, freeing enterprises and the public from cable restraints, allowing customers to control costs more effectively, reduce installation costs, and is simple and convenient to use. . In addition, the growing demand is driving the continuous development. Contrary to the continuous growth of information processing capabilities and network bandwidth, the means of information acquisition are far behind, and the demand for people is well met. The technology allows real-time monitoring of the external environment for large-scale, automated information collection. Therefore, Μ2Μ can be applied to industrial applications, home applications, personal applications, etc., in the field of industrial applications such as: traffic monitoring, warning systems, maritime rescue, vending machines, car payment, etc., in the field of home applications such as: Automatic meter reading, temperature control, etc., for personal use applications such as: life detection, remote diagnosis, etc.

通信2Μ communication object is machine-to-machine or person-to-machine, data communication between one or more machines is defined as Machine Type Communication (MTC), in this case less human-computer interaction is required, and participation in MTC Machine, defined as MTC equipment (MTC Device, MD ). The MTC device is a terminal of the MTC user, and can communicate with the MTC device and the MTC server through a public Land Mobile Network (PLMN) network.

After the M2M application is introduced, the existing system can be optimized according to its characteristics to meet the requirements of the M2M application, and it does not affect the ordinary H2H equipment in the existing system. Some notable features of the M2M application include: The number of MTC devices is huge, and the number is much higher than the existing H2H devices; the data transmission is regular, the amount of data transmitted per time is small; the mobility of MTC devices is low, and a large part of MTC devices are Not moving.

When the MTC device accesses the network, it needs to initiate random access. Figure 1 is a flow chart of the contention-based random access procedure in the existing Long Term Evolution (LTE) system, as shown in Figure 1, in LTE. The contention-based random access process mainly includes the following four steps:

Step 102: The user equipment (User Equipment, UE) randomly selects a preamble (Preamble) and transmits it on a Physical Random Access Channel (PRACH).

Step 104: After detecting the transmission of the Preamble code, the base station (eNB) sends a random access response (RAR) in the downlink, where the random access response generally includes the following information: The number of the received Preamble code The time adjustment amount corresponding to the received Preamble code, the uplink resource location indication information allocated to the terminal, and the temporary Temporary Cell Radio Network Temporary Identifier (Temporary C-RNTI) allocation.

Step 106: After receiving the random access response, the UE sends an uplink message on the allocated uplink resource according to the indication. The uplink message is also called Message 3 (Msg3), and at least should include: the terminal's unique identifier (TMSI) or random identifier (Random ID), and the establishment cause ( Establishment Cause ).

Step 108: The base station receives the uplink message of the UE, and returns a contention to the UE with successful access. Contention Resolution (also known as Msg4). If the UE receives the message before the collision resolution timer expires, and the packet is confirmed to be the Msg4 expected by the UE, it is determined that the random access procedure is successful; otherwise, the UE is re-initiated the random access. The UE re-initiating random access needs to restart from step 102.

When the number of times the user equipment sends the preamble exceeds the maximum number of transmissions (reambleTransMax), that is, the number of times the preamble is transmitted is equal to preambleTransMax +1, the random access fails. The random access of the LTE system is implemented in the medium access control (MAC). After the random access fails, the MAC layer needs to notify the upper layer of the user equipment of the failure. If the upper layer of the user equipment still needs to initiate a service, it will trigger the MAC layer to initiate random access again.

Before the introduction of the MTC device, it is initiated and released by the person to control the service. When the user needs to initiate a service, the user equipment continuously initiates random access until the random access succeeds. If the random access fails multiple times, the user may terminate the connection request of the service. However, after the introduction of the MTC device, because there is no human participation, when the MTC device has data to transmit (when the service needs to be initiated), the MTC device continuously initiates random access until the data is successfully transmitted, so that when the number of MTCs is large, When the device needs to access the network to send data or update the location area, it is easy to make the wireless resource overloaded, causing the random access initiated by the MTC device to fail, and the network cannot be successfully implemented because the MTC device continuously initiates random access. restore. Summary of the invention

In view of the above, the main purpose of the present invention is to provide a random access method and a terminal, which can solve the problem that a large number of terminals continuously initiate random access, causing network overload and cannot be successfully recovered in a random access process, and improve random access. Success rate.

In order to achieve the above object, the technical solution of the present invention is achieved as follows:

A random access method includes: after the terminal fails to access the random access, waiting for the set time to initiate random access. The set time is obtained according to the length of the waiting time pre-agreed by the protocol, or is obtained according to the waiting time length carried in the system message.

The length of the waiting time pre-agreed by the protocol or the length of the waiting time of the system message is: according to the terminal type, and/or the terminal priority, and/or the priority of the service initiated by the terminal, and/or whether the terminal initiates the service to allow the delay, And/or the group to which the terminal belongs, and/or the terminal access level, and/or the terminal roaming situation, the corresponding waiting time length set,

The terminal acquires the set time as: the terminal according to its own terminal type, and/or the terminal priority, and/or the priority of the service initiated by the terminal, and/or whether the terminal initiates the service to allow the time delay, and/or the terminal belongs to Information such as group, and/or terminal access level, and/or terminal roaming status, query protocol agreement or length of waiting time carried by the system message, and the obtained waiting time length value is used as the set time.

After the terminal selects the cell again after the random access fails, the set time is obtained according to the waiting time length carried by the system message: According to the waiting time length of the new d and the area system message, the set time is obtained.

The terminal is a machine type communication MTC device and/or a person-to-person communication H2H device.

The waiting time length of the system message is the length of the waiting time set by the network side according to the random access load or the access restriction requirement set by the core network.

A terminal is configured to wait for a set time to initiate random access after a random access failure. The set time is obtained by the terminal according to the length of the waiting time pre-agreed by the protocol, or is obtained by the terminal according to the waiting time length carried in the system message.

The length of the waiting time pre-agreed by the protocol on which the terminal obtains the set time or the length of the waiting time carried in the system message is: according to the terminal type, and/or the terminal priority, and/or the priority of the service initiated by the terminal, and / Or the terminal initiates the service whether the delay is allowed, and/or the group to which the terminal belongs, and/or the terminal access level, and/or the terminal roaming situation, and the corresponding waiting time length is set, and the terminal acquires the set time as: Its own terminal type, and / or terminal priority Level, and/or priority of the service initiated by the terminal, and/or whether the terminal initiates the service, whether the time delay is allowed, and/or the group to which the terminal belongs, and/or the terminal access level, and/or the terminal roaming situation, etc., the query protocol The length of the waiting time carried by the appointment or system message, and the obtained waiting time length value is used as the set time.

After the random access fails and the cell is reselected, the terminal acquires the set time according to the waiting time length of the system message: According to the new d, the waiting time length carried by the area system message acquires the set time.

The terminal is an MTC device and/or an H2H device.

The present invention provides a random access method and a terminal. After detecting a random access failure, the terminal waits for a set time and then initiates random access. With the present invention, after the random access fails, the terminal waits for a period of time and then re-initiates the random access, so as to avoid the radio resource shortage caused by the frequent re-initiation of the random access by the terminal in the case of the wireless resource overload. Moreover, the invention can average the number of terminals accessing the network per unit time, thereby improving the success rate of random access. DRAWINGS

1 is a flow chart of a contention-based random access procedure in an existing LTE system;

2 is a schematic flowchart of a random access method according to the present invention;

FIG. 3 is a schematic flow chart of an MTC device (referred to as MD1) accessing a network according to Embodiment 1 of the present invention. detailed description

The basic idea of the present invention is: After detecting that the random access fails, the terminal waits for the set time to initiate random access.

2 is a schematic flowchart of a random access method according to the present invention. As shown in FIG. 2, the method includes: Step 201: The terminal randomly fails to access. Step 202: After the terminal waits for the set time, the random access is initiated again.

Here, the set time may be obtained by the terminal according to the length of the waiting time pre-agreed by the protocol, or may be acquired by the terminal according to the waiting time length carried in the system message.

The protocol pre-agreed waiting time length may be: the protocol pre-agreed the waiting time length of a certain type of terminal; and/or, agreeing on the waiting time length of a certain priority terminal; and/or, arranging the terminal to initiate a certain priority service The length of the waiting time; and/or, the length of the waiting time for the terminal to initiate the delay of the service; and/or the length of the waiting time for the terminal belonging to a group; and/or the waiting for the terminal to agree on a certain access level The length of time; and/or, the length of the waiting time of the roaming terminal, in other words, according to the terminal type, and/or the terminal priority, and/or the priority of the service initiated by the terminal, and/or whether the terminal initiates the service to allow the delay, And/or the group to which the terminal belongs, and/or the terminal access level, and/or the terminal roaming situation, and the corresponding waiting time length is set by means of a protocol.

The length of the system message carrying waiting time may be: a system message includes a waiting time length of a certain type of terminal; and/or a waiting time length including a certain priority terminal; and/or, including a terminal to initiate a certain priority The length of the waiting time of the service; and/or, including the length of the waiting time when the terminal initiates whether to allow the service to be delayed; and/or, the length of the waiting time including the terminal belonging to a group; and/or, including an access level The length of the waiting time of the terminal; and/or, including the length of the waiting time of the roaming terminal, in other words, the system side may initiate according to the terminal type, and/or the terminal priority, and/or the priority of the service initiated by the terminal, and/or the terminal. Whether the service allows delay, and/or the group to which the terminal belongs, and/or the terminal access level, and/or the terminal roaming situation, sets a corresponding waiting time length, and carries the set waiting time length through the system message.

The terminal according to its own terminal type, and/or terminal priority, and/or the priority of the service initiated by the terminal, and/or whether the terminal initiates the service to allow the delay, and/or the group to which the terminal belongs, and/or the terminal access level, And/or information about the terminal roaming situation, the length of the waiting time of the protocol agreement or the system message, and the obtained waiting time length value is used as the set time. If the terminal obtains the waiting time length through the system message, the network side sets the waiting time length included in the system message according to the random access load or the access restriction requirement set by the core network.

It should be noted that, if the terminal fails to access the random access and the cell is reselected, the set time of the waiting time length according to the system message is: According to the waiting time length of the new d and the area system message, set time.

It should be noted that, in the present invention, the terminal may be an MTC device and/or an H2H device. The present invention also correspondingly proposes a terminal, which is set to wait for a set time to initiate random access after a random access failure.

The set time is obtained by the terminal according to the length of the waiting time pre-agreed by the protocol, or is obtained by the terminal according to the waiting time length carried in the system message.

The length of the waiting time pre-agreed by the protocol on which the terminal obtains the set time or the length of the waiting time carried in the system message is: according to the terminal type, and/or the terminal priority, and/or the priority of the service initiated by the terminal, and / Or the terminal initiates the service whether the delay is allowed, and/or the group to which the terminal belongs, and/or the terminal access level, and/or the terminal roaming situation, and the corresponding waiting time length is set, and the terminal acquires the set time as: Its own terminal type, and/or terminal priority, and/or the priority of the terminal originating service, and/or whether the terminal initiated service allows delay, and/or the group to which the terminal belongs, and/or the terminal access level, and/or Or the information such as the terminal roaming situation, the length of the waiting time of the protocol agreement or the system message, and the obtained waiting time length value is used as the set time.

The terminal is an MTC device and/or an H2H device.

The implementation of the technical solution of the present invention will be further described in detail below with reference to specific embodiments. Example 1 In this embodiment, a large number of MTC devices and H2H devices reside in a cell managed by any one of the LTE systems. Some of these devices are in a connected state, and some are in an idle state. At some point, some MTC devices need to initiate a service request because of data transmission. 3 is a schematic flowchart of accessing a network by an MTC device (referred to as MD1) according to Embodiment 1 of the present invention. As shown in FIG. 3, the process includes:

Step 301: MD1 initializes related parameters, such as setting the preamble transmission times ( PREAMBLE_ TRANSMISSION_COUNTER) to 1.

Step 302: MD1 randomly selects a preamble (Preamble) and transmits it on a Physical Random Access Channel (PRACH).

Step 303: Whether the MD1 receives the random access response within the predetermined time window, if yes, step 304 is performed; otherwise, step 307 is performed. In this step, the predetermined time window is a time window in which the protocol specified by the protocol receives the random access response.

Step 304: The MD1 sends the Msg3 on the indicated uplink resource (or the uplink grant) according to the received random access response, and starts a conflict resolution timer, where the Msg3 at least includes: the unique identifier of the terminal (TMSI) ) or random ID (Random ID), and Establishment Cause. It should be noted that if MD1 receives the indication sent by the base station and does not receive the response message of Msg3 (that is, the NACK message), it resends Msg3 and restarts the collision resolution timer.

Step 305: The MD1 determines whether the expected contention resolution message Msg4 sent by the base station is received before the conflict resolution timer expires. If yes, go to step 306; otherwise, go to step 307.

Step 306: The random access is successful, and the process ends.

Step 307: The number of preamble transmissions is increased by one.

Step 308: MD1 determines whether the number of preamble transmissions is greater than the maximum number of transmissions. If yes, go to step 309; otherwise, go to step 302.

Step 309: The random access fails, and the upper layer reports that the random access fails, on the MD1. The layer (the RRC layer or the non-access stratum) determines whether the service request needs to be initiated again. If necessary, wait for a period of time, and then trigger the MAC layer to initiate random access again, and MD1 restarts to perform step 301; if not, the MD1 access The flow of the network ends and MD1 remains idle.

In step 309, if the MD1 needs to continue to initiate a service request, the timer needs to be started. After the timer expires, the MAC layer can be triggered to initiate random access again. This can avoid the shortage of random access resources and the conflicts caused by a large number of MTC devices accessing the network. By delaying the time period, the number of MTC devices accessing the network per unit time can be averaged, and the random access of the MTC devices is improved. Success rate. It can avoid that a large number of MTC devices access the network at the same time, causing overload of the wireless resources, and the random access initiated again will cause the network to fail to return to the normal state.

In this embodiment, the waiting period (or the timer duration) adopts a pre-agreed manner in the protocol, and the protocol may pre-agreed the waiting time length of a certain type of terminal. For example, the MTC device needs to wait 600 seconds, and the H2H device needs to wait for 0. second;

The protocol may also pre-agreed the waiting time length of a certain priority terminal. For example, a terminal with a low priority needs to wait for 1000 seconds, and a terminal with a normal priority needs to wait for 100 seconds;

The protocol may also pre-arrange the length of waiting time for the terminal to initiate a certain priority service (or whether to allow the service to be delayed). For example, when the terminal is scheduled to initiate a low priority service (or allow the delayed service), it needs to wait for 500 seconds, and the terminal is required to initiate a high priority. Level service (or no delay in service), waiting for 100 seconds; existing protocol supports terminal to initiate high priority service (highPriorityAccess), emergency service (Emergency, emergency service priority is the highest), due to paging Initiated services (mt-Access), user-initiated signaling services (mo-signaling), user-initiated data services (mo-data), introduced for MTC devices, can add other priority services, such as electronic meter reading Business (smart meter, smart meter, etc., etc.) is a time-tolerant service. This type of service can be called low-priority service or Delay Tolerant. For monitoring services, such as monitoring vehicle anti-theft. The alarm service initiated by the MTC device belongs to a service with low time tolerance, and the service can be delineated. High priority The service can also introduce a new priority to indicate that the MTC device initiates a service that is not delayed (non Delay Tolerant).

The protocol can also pre-approve the waiting time of the terminals belonging to a group. Different terminals can belong to different groups. For example, the protocol pre-agreed for a group of terminals needs to wait 200 seconds, and other groups of terminals need to wait for 100 seconds. ;

The protocol may also pre-arrange the waiting time length of the terminal of an access class, and save the corresponding access level in the terminal, that is, the protocol may pre-agreed the waiting time length of the terminals of different access levels;

The protocol may also save the signed Local Public Land Mobile Network (HPLMN) in the terminal's User Identification Identity Card (USIM) according to whether the terminal roams in advance and waits for the length of the waiting time, or includes Equivalent Home PLMN (EHPLMN), if the terminal access network does not belong to HPLMN, or does not belong to HPLMN and EHPLMN, the terminal is a roaming terminal. If the protocol can stipulate that the waiting time of the roaming terminal is 1000. Seconds, the non-roaming terminal waits for a length of 0 seconds.

Example 2

In this embodiment, a large number of MTC devices and H2H devices reside in a cell managed by any one of the LTE systems. Some of these devices are in a connected state, and some are in an idle state. At some point, some MTC devices need to initiate a service request because of data transmission. The process of accessing the network by the MTC device (referred to as MD2) is similar to the process described in Embodiment 1, except that after determining that the number of retransmissions is greater than the maximum number of retransmissions, the upper layer of MD2 (RRC layer or non-access stratum) It is determined whether the service request needs to be initiated again. If necessary, wait for a period of time, and then trigger the MAC layer to initiate random access again. If not, the process of accessing the network by MD2 ends, and MD2 remains idle. In this embodiment, the waiting period is obtained from the system message, and when the MD2 accesses the current cell, the waiting time is obtained from the system message, but the MD2 is not immediately applied. This parameter is applied only after the random access fails.

In the existing system message, there is no cell for waiting for the random access to be initiated again. In order to implement the present invention, it is necessary to extend the existing system message and add a cell indicating the waiting time in a certain system message block. A unified waiting time can be set for all terminals in the system message;

Or set different waiting times for different types of terminals, such as setting the MTC device waiting time to 600 seconds and the H2H device waiting time to 0 seconds;

Or set the waiting time for the priority of the terminal, such as setting the waiting time of the low priority terminal (or only the MTC device) to 1000 seconds, and the normal priority terminal waiting time to 100 seconds;

Or set the waiting time for the priority of the service initiated by the terminal, such as setting the waiting time for the terminal to initiate the low priority service (allowing the delayed service) to be 5 minutes, and setting the waiting time for the other priority services to be 0 minutes;

Or set the waiting time for the access level of the terminal. For example, the waiting time for setting ACO ~ AC9 is 100 seconds, and the waiting time for other ACs is 0 seconds.

Or set the waiting time for the group to which the terminal belongs. For example, the waiting time for setting certain groups (by group ID) is 500 seconds, and the waiting time for other groups is 100 seconds.

Or set the waiting time for the roaming feature of the terminal. For example, the waiting time for the roaming terminal (or only the MTC device) is 600 seconds, and the non-roaming terminal waiting time is 0 seconds.

When the terminal enters the current cell, the terminal obtains the waiting time from the system message, and the terminal saves the parameter. If the terminal fails to access the random access because it needs to initiate a service request, the corresponding timer is started, and the timer duration is equal to the waiting time. The terminal can initiate random access again only when the timer expires. The base station sets the waiting time by using the system message, and can dynamically set the waiting time according to the current radio resource load level, and can reasonably control the number of terminals that initiate random access in a unit time. If the current random access load is high (initiating a random connection) Into The number of terminals is large. The base station sets a long waiting time through system messages to reduce the current random access collision and improve the success rate of random access of the terminal. The core network also imposes access restriction requirements on the base station according to its own load, such as The base station sends an access restriction requirement for limiting the access rate of a certain terminal, and the base station sets the waiting time length in the system message according to the requirements of the core network.

It should be noted that, if the terminal selects another cell after the random access failure occurs, and the terminal selects another cell, and the terminal initiates the random access again, the waiting time in the system message of the new resident cell needs to be applied. After the timer corresponding to the waiting time expires, the random access can be initiated again. After the terminal reselects the cell, the terminal still uses the waiting time in the original cell system message. After the timer corresponding to the waiting time expires, the random connection can be initiated again. In.

There are other implementation manners in this embodiment. The base station can set the waiting time in the random access response. After the terminal obtains the waiting time through the random access response, after the random access fails, it needs to wait for the set time, and then can again Initiate random access. This requires adding a new cell in the random access response to indicate the latency.

There are other implementation manners in this embodiment. The terminal obtains the waiting time by using the system message. After the terminal randomly fails to access the terminal, the terminal takes a random number between 0 and the waiting time as the actual waiting time, and only expires in the actual waiting time. After that, random access can be initiated again.

Example 3

In the Wideband Code Division Multiple Access (WCDMA) system of this embodiment, a large number of MTC devices and H2H devices reside in a cell under the jurisdiction of a Radio Network Control (RNC). Some of these devices are connected and some are idle. At some point, some MTC devices need to initiate a service request because of data transmission. One of the MTC devices (called MD1) initiates random access by:

The random access procedure of the physical layer in WCDMA is triggered by the MAC layer. The physical layer first determines the random access resources according to the parameters obtained from the RRC layer and the MAC (signature and available). The time slot) and the power of the Preamble, the Preamble (RACH Preamble part), and the AI reception, there are three cases:

1. The ACK identifier is received on the downlink time slot: The physical layer sends an access message to the network side (RACH Message part). ₀ After the data transmission is completed, the state "RACH message transmitted" is fed back to the MAC layer, and the physical random access procedure is exited. . This indicates that the random access is successful.

2. The NACK identifier is received on the downlink time slot: At this time, the physical layer feeds back the status "Nack on AICH received" to the MAC and exits the physical random access procedure.

3. If neither the ACK nor the NACK is received: At this time, if the number of transmissions of the Preamble does not reach the upper limit Trans-Max, the physical layer will reselect the random access resource, increase the transmission power, and perform random access again; If the number of transmissions of the Preamble reaches the upper limit, the physical layer feeds back the status "No ack on AICH" to the MAC layer and exits the physical random access procedure.

If the upper layer of MD1 does not receive the "RACH message transmitted" of the physical layer feedback, it indicates that the random access fails. If MD1 still needs to initiate a service request, it will trigger the physical layer to implement the random access procedure again. At this time, it is necessary to wait for a period of time, which can be controlled by the RRC layer, or controlled by the MAC layer, or controlled by the physical layer. The waiting time can be set in a pre-agreed manner in the protocol or set by system messages. The protocol is agreed in the same manner as the method described in Embodiment 1, and the system message setting is the same as that described in Embodiment 2.

By setting the waiting time, the number of terminals that initiate random access in a unit time can be controlled, and the success rate of random access of the terminal is improved. It can avoid overloading of wireless resources caused by a large number of terminals accessing the network at the same time.

In this embodiment, if the terminal reselects other cells before the terminal initiates random access again, the terminal deletes the configuration of the original cell waiting time, and immediately initiates random access in the new cell.

It should be noted that, in the case of no conflict, the embodiments and examples in the present application Features can be combined with each other.

Obviously, those skilled in the art should understand that the above modules or steps of the present invention can be implemented by a general-purpose computing device, which can be concentrated on a single computing device or distributed over a network composed of multiple computing devices. Alternatively, they may be implemented by program code executable by the computing device, such that they may be stored in the storage device by the computing device and, in some cases, may be different from the order herein. The steps shown or described are performed, or they are separately fabricated into individual integrated circuit modules, or a plurality of modules or steps are fabricated as a single integrated circuit module. Thus, the invention is not limited to any specific combination of hardware and software.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Any modifications, equivalent substitutions, improvements, etc. within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims

Claim

A random access method, where the method includes: after the terminal fails to access the random access, and waits for the set time to initiate random access.

The random access method according to claim 1, wherein the set time is obtained according to a predetermined waiting time length of the protocol, or is obtained according to a waiting time length carried in the system message.

The random access method according to claim 2, wherein the length of the waiting time pre-agreed by the protocol or the length of the waiting time carried by the system message is: according to the terminal type, and/or the terminal priority, and/or the terminal. The priority of the originating service, and/or whether the terminal initiated service allows delay, and/or the group to which the terminal belongs, and/or the terminal access level, and/or the corresponding waiting time length of the terminal roaming situation setting,

The random access method according to claim 2 or 3, wherein, in the case that the terminal reselects the cell after the random access fails, the set time of the waiting time length according to the system message is: The set time is obtained according to the waiting time length carried by the new d and zone system messages.

The random access method according to claim 2 or 3, wherein the terminal is a machine type communication MTC device and/or a person-to-person communication H2H device.

The random access method according to claim 2 or 3, wherein the length of the waiting time carried by the system message is an access restriction set by the network side according to a random access load or a core network. The length of waiting for the demand setting.

7. A terminal, wherein the terminal is configured to wait for a set time to initiate random access after a random access failure.

The terminal according to claim 7, wherein the set time is obtained by the terminal according to a waiting time length pre-agreed by the protocol, or is acquired by the terminal according to the waiting time length carried in the system message.

The terminal according to claim 8, wherein the length of the waiting time pre-agreed by the protocol according to the protocol for which the terminal acquires the set time or the waiting time of the system message is: according to the terminal type, and/or the terminal priority. And/or the priority of the service initiated by the terminal, and/or whether the terminal initiates the service, whether the delay is allowed, and/or the group to which the terminal belongs, and/or the terminal access level, and/or the terminal roaming situation, and the corresponding waiting time set. Length,

The terminal according to claim 8 or 9, wherein, in the case that the cell is reselected after the random access fails, the terminal acquires the set time according to the length of the waiting time carried in the system message: according to the new d The waiting time length carried by the zone system message acquires the set time.

The terminal according to claim 8 or 9, wherein the terminal is an MTC device and/or an H2H device.