WO2012024996A1

WO2012024996A1 - Random access method and system thereof

Info

Publication number: WO2012024996A1
Application number: PCT/CN2011/077493
Authority: WO
Inventors: 李兰兰; 戴谦; 艾建勋
Original assignee: 中兴通讯股份有限公司
Priority date: 2010-08-24
Filing date: 2011-07-22
Publication date: 2012-03-01
Also published as: CN102378364B; CN102378364A

Abstract

A random access method is disclosed, which includes the following steps: a benchmark back-off time is pre-configured in a Machine Type Communication User Equipment(ME) or the benchmark back-off time is sent to the ME by a network side, and an adjustment factor is sent to the ME by the network side; the ME adjusts, using the adjustment factor, the benchmark back-off time to obtain a special back-off time, and sends a random access request according to the special back-off time when the ME reinitiates the random access. A corresponding system is also disclosed by the present invention. The present invention enables the ME and a Human to Human(H2H) terminal to use differentiated back-off time for reinitiating random access process, thus resolving the problem of network congestion led by using the same back-off time by the H2H terminal and the ME.

Description

Random access method and system for realizing random access

The present invention relates to the field of communications technologies, and in particular, to a random access method and a system for implementing random access.

Background technique

M2M (Machine to Machine) is a concept put forward in the 1990s and an important driving force for the development of communication technology. Simply put, M2M is the machine's Internet, and the means of implementation include various networking technologies. The goal of M2M technology is to enable all machines and equipment to have networking and communication capabilities. The core concept is Network Everything. M2M's communication objects are machine-to-machine or human-to-machine. Data communication between one or more machines is defined as MTC (Machine Type Communication), in which case less human interaction is required. The machine participating in MTC is defined as MTC terminal (MTC UE, ME). The MTC terminal is the terminal of the MTC user and can communicate with other MTC terminals and MTC servers via PLMN (Public Land Mobile Telephone Network). 1 is an MTC network structure in an LTE (Long Term Evolution) architecture. As shown in FIG. 1 , an MTC UE is a terminal device that communicates with an MTC server through an operator network, and an MTC contractor is an entity that provides services for an MTC terminal, including Multiple MTC users. MTC users are connected to the PLMN network through the MTC server, which provides services to MTC users.

In FIG. 1, the control plane protocol on the LTE-Uu interface uses a Radio Resource Control (RRC) layer protocol, and the RRC layer is an Evolved Universal Terrestrial Radio Access Network (EUTRAN) wireless. The core of resource management, including system messages and paging. System Information (SI) is an RRC message carrying System Information Blocks (SIBs) with the same scheduling period, that is, SI is the transport container of the SIB. Each SIB contains a set of content-related system parameters. There are many types of SIBs, mainly including MIB (Main System Information Block), SIB1 and SIBn (η = 1 ... 11 ), and the information carried in these message blocks is different.

The process of the UE (user equipment) acquiring system information is as shown in FIG. 2. If the content of the system information changes, the base station sends a paging message to the UE, and includes a system information change in the paging message. The indication (system Info Modification), then the UE performs the system information acquisition process. The signaling procedure of the base station paging the UE is as shown in FIG. 3. When the base station sends a paging message to the UE, the base station transmits a P-RNTI (Paging-Radio Network Temporary Identity) on the PDCCH (Physical Downlink Control Channel). After the UE reads the P-RNTI on the PDCCH channel, the specific content of the paging message is read on the PDSCH. For the MTC terminal, a paging tag MTC_P_RNTI can be added. When the normal UE reads this tag, the content of the paging message is not read.

Random access is one of the most basic functions of a terminal in a wireless communication system, which makes it possible to establish a connection between the terminal and the network. As the name suggests, the initiation of such access and the resources used are random, and the success of access is also random. There are two modes of random access: based on the competitive mode and based on the non-competitive mode. The flow of the random access process in these two modes is different and is applicable to different scenarios.

The random access based on the contention mode is applicable to: RRC-IDLE (initial access in the radio link layer-idle state); initial access after the radio link error; RRC-CONNECTED (wireless link layer-connection) In the state, uplink data transmission.

The random access based on the non-contention mode is applicable to: RRC-CONNECTED state, downlink data transmission; random access procedure of the terminal in the handover process.

FIG. 4 is a random access process based on a competition mode in the prior art, including:

401: a user equipment (UE) sends a random access preamble to an evolved base station (eNB);

Before initiating the random access request, the UE randomly selects a transmission opportunity from the available random access transmission opportunities, randomly selects a preamble from the available preamble set, and transmits the selected preamble to the base station.

402: The eNB sends a random access response message to the UE.

After the eNB correctly solves one or more preambles on a random access transmission opportunity, the eNB calculates a corresponding RA-RNTI (random access-wireless network temporary identifier) according to the transmission opportunity. According to the above information, a random access response medium access layer packet data unit (RAR MAC PDU) as shown in FIG. 5 is generated. As shown in FIG. 5, the sub-header in the MAC header and the RAR field in the payload are - corresponding of.

In addition, the eNB may further determine, according to the current random access load status, whether to add a fallback (backward, BO) subheader in the random access response MAC PDU, and the backoff subhead carries the backoff time. The function is that the user does not immediately send the preamble to the next available random access opportunity in the event of a random access collision, but retransmits the preamble after a period of backoff delay. The probability of a collision between low users.

The structure of the fallback subheader is shown in Figure 6. The field E is used to indicate whether there is a subheader in the ET-RAPID format after the BI field. The field T is used to indicate whether the field after the field is BI or RAPID, and the two fields R Indicates two bits reserved. When the H2H (person-to-person communication) type UE (R8 and R9 terminals) reads the two reserved fields, the values of the two fields are ignored, and the BI field indicates that the UE is randomly accessed. The selection range of the backoff time.

403: The terminal identifies that the UE sends an RRC message with a user identifier to the eNB.

If multiple UEs select the same preamble to transmit in the same transmission opportunity in step 401, then multiple UEs receive the same random access response message in step 402, and these UEs have the same C-RNTI (Cell Radio) The network temporary identifier), message 3 (RRC message) contains information that can uniquely identify different UEs.

404: The contention is eliminated, and the eNB sends a collision resolution message to the UE.

Since there may be multiple UEs simultaneously transmitting their own message 3 in the same uplink grant, the eNB correctly demodulates a message 3 from it, and sends a message 4 (collision resolution message) on the PDCCH to the PDCCH corresponding to the message 4 (physical Downlink Control Channel) The content is scrambled by the C-RNTI of the UE included in Message 3. The UE uses its own C-RNTI to receive the PDCCH. If the PDCCH can be correctly received, the random access is considered successful.

In the random access process, there are two situations in which the fallback mechanism can be used. One is a random access answer exception, specifically, if the UE does not receive the RAPID it sent in the random access response, or does not receive the random access response within a certain length of time. In another case, as described in step 402 above, a collision occurs in the UE random access procedure, and some UEs have a random access failure.

In addition, when the base station is in an overload situation, for example, it is no longer possible to allocate more resources for transmitting the message 3, etc., it is desirable that some UEs can delay the transmission of the RACH (random access) request for a period of time, and can receive the random access. When responding, it is implemented by the fallback parameter in the random access response message format. This fallback parameter is the parameter of the fallback mechanism. If the UE that listens to the random access response message finds a backoff indication, then this will be returned. The value of the return value is saved. When the random access needs to be performed again, a value can be randomly selected from 0 to the back-off value as the time for delaying the transmission of the preamble. In the prior art, the unit of the backoff time parameter is milliseconds, and one of the following 12 values can be selected: ₀ , ₂₀ , ₃₀ , ₄₀ , 60, 80, 120, 160, 240, 320, 480, and 960. The backoff parameter carried in the random access response message sent by the base station to the terminal is determined according to the load level. The same fallback parameter is used for terminals accessing from within a serving cell.

The number of terminals in the MTC network is large. When a large number of terminals initiate random access requests to access the network at the same time, resources in the network will be insufficient, and a large number of MTC devices will fail to access, so they will re-access during the backoff time. . A large number of MTC devices initiate random access requests in a short period of time, which also causes network congestion.

For example, the power meter reading service stipulates that MTC devices send data to the network at a specific time, and these MTC devices are required to simultaneously access the network at a specific time. When a large number of MTC devices access the network at the same time, the probability of random access collisions is relatively large. A large number of MTC devices may fail to access randomly. These MTC devices that fail to access the network will re-access the network. In order to alleviate the congestion caused by a large number of MTC devices accessing the network in a short time, a long backoff time is required. The MTC device selects a time to reconnect to the network within a longer backoff time. However, in order not to affect the user's service quality, if a random access collision occurs in the H2H terminal, it is usually necessary to access the network as soon as possible, and a shorter backoff time needs to be set in the random access response.

On the other hand, in some application scenarios, when the MTC device has time sensitivity, the MTC device has a higher access priority than the normal UE. In this case, the MTC device needs to obtain a smaller response than the H2H terminal. Retreat time. When the H2H terminal and the MTC device access the network in a serving cell, the base station does not distinguish the terminal type and then sends the difference RAR MAC PDIL. The fallback carried by the random access response sent by different terminals in the same RAR MAC PDU The time is also the same, and the H2H terminal and the MTC device cannot obtain different backoff times. Therefore, in the prior art, different random access backoff times cannot be fed back to the H2H terminal and the MTC device, so that network congestion caused by the MTC device during the random access process cannot be solved. Summary of the invention

The technical problem to be solved by the present invention is to provide a random access method and a system for implementing random access, so that the MTC terminal uses the re-initiation of the random access backoff time different from the H2H terminal and accesses the network.

To solve the above technical problem, a random access method of the present invention includes:

The reference backoff time is pre-configured in the machine type communication terminal (ME) or the reference backoff time is sent to the ME by the network side, and the network side sends the adjustment factor to the ME;

ME adjusts the reference backoff time by using the adjustment factor to obtain a dedicated backoff time. When random access is initiated, a random access request is sent according to the dedicated backoff time.

Preferably, the basic backoff time is a backoff time used when the person-to-person communication (H2H) terminal re-initiates random access, or is a backoff time constant;

When the basic backoff time is the backoff time used by the H2H terminal, it is sent to the ME by the network side. When the basic backoff time is the backoff time constant, it is pre-configured in the ME or sent to the ME by the network side.

Preferably, the network side sends a backoff time constant and an adjustment factor to the ME through a system message or a paging message.

Preferably, the method further comprises:

The network side configures corresponding adjustment factors for different machine type communication (MTC) packets, service priorities or access priorities, and sets different packets, service priorities or access priorities through system messages or paging messages. The corresponding adjustment factor is sent to the corresponding ME.

Preferably, the method further comprises:

The network side carries the identification information of the packet, the service priority or the access priority in the system message or the paging message to be sent to the corresponding ME.

Preferably, the network side configures a corresponding adjustment factor for different MTC packets according to the service priority or the access priority, and sends the adjustment factor corresponding to the packet to the ME in the packet by using a system message or a paging message.

A random access method, including:

The network side adjusts the reference backoff time by using the adjustment factor to obtain a dedicated backoff time, and sends the obtained dedicated backoff time to the machine type communication terminal (ME);

When the ME re-initiates random access, it sends a random access request according to the dedicated backoff time.

Preferably, the network side adjusts the reference backoff time for different machine type communication (MTC) packets, service priorities or access priorities, and uses a corresponding adjustment factor, and will use system messages or paging messages. The obtained dedicated backoff time is sent to the ME under different packet, service priority or access priority.

A system for implementing random access, comprising: a base station and a machine type communication terminal (ME), the base station includes an information sending module, and the ME includes an access request module, wherein:

The information sending module is configured to: send the reference backoff time and the adjustment factor to the access request module; The access request module is configured to: adjust the reference backoff time received or pre-configured from the information sending module by using an adjustment factor to obtain a dedicated backoff time, and when the random access is re-initiated, the random backoff is sent according to the dedicated backoff time. Into the request.

The information sending module is configured to: send a back time constant and an adjustment factor to the access request module through a system message or a paging message.

The information sending module is configured to: adjust the reference backoff time by using the adjustment factor, obtain a dedicated backoff time, and send the obtained dedicated backoff time to the access request module;

The access request module is set to: When re-initiating random access, a random access request is sent according to the dedicated backoff time.

In summary, the embodiment of the present invention uses the ME to obtain the reference backoff time in a way that is pre-configured in the ME or sent by the network side, and sends the adjustment factor to the ME by means of the network side, and the ME uses the adjustment factor. The reference backoff time is adjusted to obtain a dedicated backoff time, so that the ME and the H2H terminal can re-initiate the random access process by using the differentiated backoff time, which solves the same backoff time of the H2H terminal and the ME, resulting in the same backoff time. The problem of network congestion. BRIEF abstract

1 is a schematic diagram of an MTC network architecture based on LTE in the prior art;

2 is a flow chart of system message acquisition in an EUTRAN architecture in the prior art;

3 is a flow chart of a paging process in an EUTRAN architecture in the prior art;

4 is a flow chart of a random access procedure in the prior art;

5 is a schematic structural diagram of a random access response message MAC PDU in the prior art;

6 is a schematic diagram of a backoff subheader in a random access response message in the prior art; FIG. 7 is a flowchart of an example of a random access method in the present embodiment;

FIG. 8 is a structural diagram of a system for implementing random access in the embodiment. Preferred embodiment of the invention

Considering that when the ME accesses the network randomly, network congestion occurs. When the ME needs to re-access, it needs to use a random access backoff time different from that of the H2H terminal (ordinary terminal). In this embodiment, the ME uses the adjustment factor to adjust the reference backoff time to obtain a dedicated backoff time. When the random access is re-initiated, the random access request is sent according to the dedicated backoff time. The back-off time used by the normal terminal to re-initiate random access or the preset back-off time constant can be used as the reference back-off time. The network side carries the backoff time applicable to the common terminal in the random access response message, and the ME adjusts the backoff time received in the random access response message as its own dedicated backoff time; the backoff time constant can be preset in the ME. It can also be preset on the network side (such as a base station), and the ME side notifies the ME by using a system message or a paging message. And the preset backoff time constant can be a tunable parameter, and the network side can adjust this parameter according to the load level. The adjustment factor is notified to the ME by the network side through system messages or paging messages.

In order to implement different dedicated backoff times, different service priorities, different access priorities, and different dedicated backoff times, MEs in different MTC packets may be used for different MTC packets, service priorities, or connections. The adjustment factor corresponding to the priority configuration, the air interface is used to notify the ME, the access priority, or the service priority in the packet in the system message or the paging message for different MTC packets, service priorities, or access priorities. The ME corresponds to the adjustment factor.

In order to achieve different service priority or access priority, the MTC packets use different backoff times. According to the service priority or the access priority, corresponding adjustment factors can be configured for different MTC packets, and the air interface is used for different services. The priority or access priority MTC packet, in the system message or the paging message, notifies the ME of the adjustment factor corresponding to the different service priority or the access priority.

The adjustment factor can be a proportional parameter. At this time, the ME can perform the operation of multiplying the reference backoff time according to the adjustment factor. The adjustment factor can also be an offset, and the ME can add the reference backoff time according to the offset.

In addition, the base station can also adjust the reference backoff time by using the adjustment factor to obtain a dedicated backoff time, and notify the ME of the dedicated backoff time in the system message or the paging message. For the MTC packet terminal, the base station may notify the ME of the dedicated backoff time corresponding to the MTC packet in which it is located in the system message or the paging message. The ME in the above MTC packet refers to a terminal that belongs to a member of a certain group according to a subscription or a dynamic allocation group identifier. At this time, the terminal has a group ID (Group ID).

When the network side notifies the ME of the adjustment factor or the dedicated backoff time, it can use existing system messages (such as SIB2), add system messages, or page messages. The adjustment factor or the dedicated backoff time is notified to the ME as a cell in the message, as follows:

1) If the network side completes the transmission through the existing SIB message, the existing SIB2 system message can be used to notify the ME of the adjustment factor or the dedicated backoff time by using the system message change process in the prior art, that is: The network side first sends a paging message to notify the ME system that the message has changed. The ME reads the new system message. If the adjustment factor is for an MTC packet or service priority or access priority, it needs to be carried in the SIB2 system message. The identification information of the MTC packet or the service priority or the access priority, and the identification information is a cell of the SIB2 system message.

2) If a system message is added to the ME, such as SIB-m, similar to the scheduling method of the SIB system message in the prior art, the scheduling information (such as the transmission window and the transmission period) of the newly added SIB message is performed in SIB1. Configuration. An indication message is added to the paging message to indicate whether the SIB-m has changed. If the content of the SIB-m changes, the base station sends a paging message to the ME, where the message carries the indication that the content of the SIB-m changes. When the ME receives the paging message, the normal terminal does not receive the content in the system message SIB-m, and only the ME receives the content of the newly added system message. If the adjustment factor is for an MTC packet or Service Class or Access Class, then the new SIB message needs to carry the MTC packet or the Service Class or Access Class identifier information, and the information is notified to the ME as a cell of the SIB message.

3) If the base station directly sends the ME dedicated backoff time or adjustment factor through the paging message. If the backoff time adjustment factor is for a certain MTC packet or service priority or access priority, the paging message needs to carry the identifier information of the MTC packet or the service priority or the access priority as the paging message. A cell notification to the ME.

The network side (such as a base station) may carry an adjustment factor in a system message or a paging message sent at power-on. When the load changes during the operation of the base station, the base station also needs to adjust the size of the adjustment factor used in the random access fallback process of the MTC terminal. When the adjustment factor size changes, the base station re-sends the paging message or the system to the ME. Message. If the normal terminal receives the system message or the paging message, the value of the corresponding cell corresponding to the adjustment factor is ignored. If the ME receives a system message or a paging message, it adjusts the backoff time or the preset backoff time constant in the random access response message. Get the dedicated backoff time of the ME. When the load of the base station changes, the base station expects that the backoff time of the random access of the ME also changes accordingly. The base station needs to notify the ME of the latest adjustment factor or dedicated backoff time. After receiving the system message or the paging message, the ME saves the adjustment factor or the dedicated backoff time in the message, and uses the new adjustment factor or the dedicated backoff time when the next random access needs to be rolled back.

The adjustment factor can be a proportional parameter. The scale factor can be a positive number greater than 1 or less than 1 depending on the degree of network load. When the adjustment factor is a proportional parameter, the ME performs a product operation on the backoff time or the preset backoff time constant in the received random access response. In some application scenarios (such as ATM monitoring), the ME needs to have a higher access priority than the normal terminal. The random access backoff time required by the ME is shorter than that of the ordinary terminal. In this case, the base station needs feedback to the ME less than 1. The proportional parameter; otherwise, the MTC terminal needs to use a longer backoff time than the normal terminal in the random access process, and the base station feeds back to the proportional parameter that the ME is greater than 1.

The adjustment factor can be a time offset. Depending on the degree of network load, the time offset can be a positive or negative number. If it is negative, the adjusted backoff time must be greater than zero. If the adjustment factor fed back to the ME in the system message or the paging message is an offset, the ME performs a summation operation on the backoff time or the preset backoff time constant in the received random access response. In some application scenarios (such as ATM monitoring), the ME needs to have a higher access priority than the normal UE. The random access backoff time required by the ME is shorter than that of the ordinary terminal. In this case, the base station needs to feed back to the ME less than zero. Offset; otherwise, the MTC terminal needs to use a longer backoff time than the normal terminal in the random access process, and the base station feeds back the offset of the ME greater than zero.

FIG. 7 is an example of a random access method according to an embodiment of the present disclosure, including the steps of:

701: The ME sends a random access request message to the base station.

When the ME needs to access the network, it can use the random access method such as competition to access.

There are various triggering conditions for the ME to initiate random access, such as receiving a trigger message sent by the network side and triggering the ME power-on. The ME randomly selects a sender from among the available random access transmission opportunities, and sends a random access request message on the selected transmission opportunity.

702: After receiving the random access request message, the base station determines, according to its processing capability, whether there are sufficient resources to process the random access request initiated by the ME.

703: If the base station is in an overload condition, the random access response message carries the backoff time of the normal terminal to re-initiate the random access; The fallback time of the ordinary terminal is carried in the BI field field as shown in FIG. 6.

704: The base station sends an adjustment factor to the ME by using a paging message or a system message.

The base station can notify the ME of the backoff time constant.

705: After receiving the random access response message, the ME obtains the backoff time of the ordinary terminal, and performs an adjustment operation on the returned time or the backoff time constant of the received common terminal by using the adjustment factor to obtain a dedicated fallback of the ME. Time

The base station can also directly notify the ME of the dedicated backoff time of the ME.

The adjustment factor is obtained from a paging message or a system message. If it is an adjustment factor dedicated to the MTC packet or a dedicated backoff time, then the packet identifier needs to be carried in the paging message or the system message.

706: The ME determines whether it is necessary to re-initiate the random access procedure.

If the random access response message received by the ME is abnormal, for example, the response message does not carry the RAPID or the terminal does not receive the random access response message, the terminal re-initiates the random access procedure. If the ME and other terminals use the same random access preamble, a collision will occur, and the terminal random access failure will occur. In this case, the ME will also re-initiate the process of random access to the network.

707: If the ME determines to re-initiate the random access procedure, randomly selects a value in the dedicated backoff time, and the ME delays the selected time and then re-initiates the random access procedure.

FIG. 8 is a system for implementing random access according to the embodiment, including: a base station and an ME, where the base station includes an information sending module, and the ME includes an access request module, where:

The information sending module is configured to send the reference backoff time and the adjustment factor to the access request module by using a system message or a paging message; the basic backoff time is a back time used when the person-to-person communication (H2H) terminal re-initiates the random access Retreat time, or a back time constant;

The access requesting module is configured to adjust the reference backoff time received or pre-configured from the information sending module by using an adjustment factor, to obtain a dedicated backoff time, and when the random access is re-initiated, the random backing is sent according to the dedicated backoff time. Into the request.

Or, the information sending module adjusts the reference backoff time by using an adjustment factor, obtains a dedicated backoff time, and sends the obtained dedicated backoff time to the access request module;

When the access request module re-initiates the random access, the access request module sends a random access request according to the dedicated backoff time. For other functions of each module in the above system, please refer to the description of the method content.

It should be noted that the methods provided in the foregoing Embodiments 1 and 2 are not only applicable to the LTE system, but also to other paging mobile communication systems, such as UMTS, GSM, and the like. The only difference is that different mobile communication systems implement paging or cell public information details that do not affect the implementation of the method provided by the present invention.

The above description 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. made within the spirit and scope of the present invention are intended to be included within the scope of the present invention.

Industrial applicability

In the embodiment of the present invention, the ME obtains the reference backoff time in a manner of being pre-configured in the ME or sent by the network side, and sends the adjustment factor to the ME by means of the network side, and the ME uses the adjustment factor to the reference backoff time. The adjustment is performed to obtain a dedicated backoff time, so that the ME and the H2H terminal can re-initiate the random access procedure by using the differentiated backoff time, and solve the problem of network congestion caused by the same backoff time of the H2H terminal and the ME. .

Claims

Claim

1. A random access method, comprising:

Transmitting a reference backoff time in a machine type communication terminal (ME) or transmitting the reference backoff time to the ME by a network side, and the network side transmits an adjustment factor to the ME; And adjusting the reference backoff time by using the adjustment factor to obtain a dedicated backoff time. When the random access is re-initiated, the random access request is sent according to the dedicated backoff time.

2. The method of claim 1 wherein

The basic backoff time is a backoff time used when a person-to-person communication (H2H) terminal re-initiates random access, or is a backoff time constant;

When the basic backoff time is the backoff time used by the H2H terminal, the network sends the ME to the ME; when the basic backoff time is the backoff time constant, the pre-configured time is In the ME, or sent by the network side to the ME.

3. The method of claim 2, wherein

The network side sends the backoff time constant and the adjustment factor to the ME through a system message or a paging message.

4. The method of claim 3, wherein the method further comprises:

The network side configures a corresponding adjustment factor for different machine type communication (MTC) packets, a service priority or an access priority, and uses the system message or the paging message to prioritize the different packets and services. Or the adjustment factor corresponding to the access priority is sent to the corresponding ME.

5. The method of claim 4, wherein the method further comprises:

The network side carries the identification information of the packet, the service priority, or the access priority in the system message or the paging message, to be sent to the corresponding ME.

6. The method of claim 3, wherein

The network side configures a corresponding adjustment factor for different MTC packets according to the service priority or the access priority, and adjusts the adjustment factor corresponding to the packet by using the system message or the paging message, Sent to the ME in the packet.

7. A random access method, comprising:

When the ME re-initiates random access, the random access request is sent according to the dedicated backoff time.

8. The method of claim 7, wherein

The network side adjusts the reference backoff time for different machine type communication (MTC) packets, service priority or access priority, and uses a corresponding adjustment factor, and obtains the system message or the paging message. The dedicated backoff time is sent to the ME under the different packet, service priority or access priority.

A system for implementing random access, comprising: a base station and a machine type communication terminal (ME), the base station includes an information sending module, and the ME includes an access request module, where:

The information sending module is configured to: send a reference backoff time and an adjustment factor to the access request module;

The access request module is configured to: adjust, by using the adjustment factor, the reference backoff time received or pre-configured from the information sending module to obtain a dedicated backoff time, and when re-initiating random access, A random access request is sent according to the dedicated backoff time.

10. The system of claim 9, wherein

The information sending module is configured to: send the backoff time constant and the adjustment factor to the access request module by using a system message or a paging message.

The information sending module is configured to: adjust the reference backoff time by using an adjustment factor, Dedicating a dedicated backoff time, and sending the obtained dedicated backoff time to the access request module; the access requesting module is configured to: when re-initiating random access, sending a random according to the dedicated backoff time Access request.