CN102811496A - A random access method - Google Patents

Abstract

The invention provides a random access method. After sending a random access pilot frequency code on a physical random access channel resource, UE (user equipment) determines a RA-RNTI (random access-radio network temporary identity) as well as a common sub-band and a wireless frame used by a base station for the authorization of a physical downlink control channel PDCCH according to an index number Preamble_id of a sent random access sequence and the index number of a cluster in which a used synchronization sub-band is located, so as to skip to the wireless frame and the common sub-band to monitor a random access response. After receiving the Preamble code sent by the UE, the base station determines a wireless frame and a common sub-band used in sending the random access response based on the same method as the UE. Therefore, the UE supporting a single sub-band working mode is ensured to be able to normally accomplish the random access process, and the random access method is suitable for a wideband access system in which ''UE supporting single sub-band working mode'' is introduced.

Description

A random access method

technical field

The present invention relates to a random access technology in a wireless communication system, in particular to a random access method in a broadband access system.

Background technique

Random access technology is an important technology of medium access control in communication system. In the broadband access system based on TD-LTE technology, random access is the access process of user equipment (UE, UserEquipment) before starting to communicate with the network, and is mainly used for initial access of user equipment, radio resource control (RRC ) connection re-establishment and switching purposes. Fig. 1 is the flowchart of the contention random access method in the existing LTE system, mainly including 4 steps:

In step 1, the UE sends a random access Preamble code on an uplink random access channel.

Step 2, the base station (eNB) transmits a random access response on the downlink shared channel (DL-SCH).

In this step, the base station needs to first authorize the Physical Downlink Control Channel (PDCCH) to the UE to notify the UE of the Physical Downlink Shared Channel (PDSCH) used to send the random access response, and then send the carried Random Access Response with Random Access Radio Network Temporary Identity (RA-RNTI). The RA-RNTI matches the physical random access channel resource used by the UE to send the Preamble code in step 1. In this way, when the UE receives the random access response carrying the RA-RNTI within the random access response window, it considers that the random access response received this time is successful, and will continue to perform step 3, otherwise it considers that the random access response for this access is If the incoming response fails, step 1 will be performed again to re-initiate the random access process.

In step 3, the UE sends the first uplink transmission information on the UL-SCH channel.

Here, when the UE successfully receives the random access response, it will send and transmit information for the first uplink transmission according to the uplink authorization carried in the random access response. This step supports HARQ, and the maximum number of retransmissions of HARQ is notified by the upper layer.

Step 4, the eNB transmits the contention resolution information on the DL-SCH channel.

Here, after successfully receiving the message sent by the UE in step 3, the base station will include the contention resolution identifier for the UE in the contention resolution information fed back. In this way, when the UE successfully receives the contention resolution information including the contention resolution identifier during the start of the contention decision timer, it considers that the random access is successful; otherwise, it considers that the random access fails.

In a broadband access system, the available bandwidth of the system is divided into a plurality of continuous or discontinuous sub-bands, and each sub-band is transmitted using Orthogonal Frequency Division Multiplexing (OFDM) technology. The subbands are divided into synchronous subbands and common subbands according to their functions. The main function of the synchronization subband is the synchronization and broadcast channel of the uplink and downlink. Figure 2 shows the synchronous subband structure in 4 radio frames, as shown in Figure 2, each radio frame contains 5 subframes, where the first subframe is a downlink subframe, and the second subframe is a special Subframes, the third, fourth, and fifth subframes are uplink subframes, and the uplink part of the special subframe and the uplink subframe will be used as PRACH resources, that is, the shaded part shown in Figure 2 allows users of a cell to perform random access . Common subbands are used for normal traffic transmission.

In order to reduce cost and implementation complexity, the technology of "UE supports single subband working mode" is introduced in the broadband access system at present, that is, the UE receiver bandwidth does not have to be the entire system bandwidth, and only supports receiving a single subband instead of receiving all Subband. In this way, the requirement on the bandwidth of the UE receiver can be reduced, and the requirement on the hardware capability of the system can also be reduced. One of the typical application scenarios is the power load monitoring communication network. Its spectrum is discretely distributed in the 230M frequency band, and its bandwidth is 8.15MHz. There are 40 sub-bands of 25kHz in total. The subband is 231.65MHz.

In the above random access method of the LTE system, the UE receiver bandwidth is the entire system bandwidth, that is, the UE needs to receive data on all subbands. In this way, for a broadband access system in which the UE supports a single subband working mode, due to the limited receiving bandwidth of the UE, it cannot receive multiple subbands at the same time, and the UE may not be able to know the sending subband of the random access response. The random access response message is received normally, therefore, the random access method of the UE cannot be realized by using the existing LTE system random access method.

Contents of the invention

In view of this, the main purpose of the present invention is to provide a random access method, which is applicable to a broadband access system that introduces "the UE supports a single subband working mode".

In order to achieve the above object, the technical scheme proposed by the present invention is:

A random access method, the method is aimed at a user equipment UE supporting a single subband working mode, and the method includes the following steps:

a. The user equipment UE determines the synchronization subband used for the current random access, and randomly selects one of the random access sequences corresponding to the cluster where the synchronization subband is located as the current random access sequence; on the synchronization subband Send the selected random access sequence to the base station; determine the random access wireless network temporary identifier RA-RNTI and the base station according to the index number preamble_id of the selected random access sequence and the index number f_id of the cluster where the synchronization subband is located Common subbands and radio frames for sending random access response messages;

b. The base station determines the RA-RNTI and the RA-RNTI used to send the random access response message according to the received index number preamble_id of the random access sequence and the index number f_id of the cluster where the synchronization subband is located Common subbands and radio frames: sending a random access response message carrying the RA-RNTI to the UE by using the normal subbands and radio frames used for sending a random access response message;

c. If the UE monitors the random access response message carrying the RA-RNTI on the normal subband and radio frame used to send the random access response message, send the first uplink transmission information to the Otherwise, the base station determines that the random access fails, and exits the method;

d. The base station sends contention resolution information including the contention resolution identifier to the UE according to the received information of the first uplink transmission; if the UE successfully receives the contention resolution information during the start of the contention determination timer contention resolution information, it is determined that this random access is successful, otherwise it is determined that this random access fails.

The present invention provides another random access method. The method is aimed at a user equipment UE supporting a single subband working mode. The method includes the following steps:

a. The user equipment UE determines the synchronization subband used for the current random access, and randomly selects one of the random access sequences corresponding to the cluster where the synchronization subband is located as the current random access sequence; on the synchronization subband Send the selected random access sequence to the base station; determine the random access wireless network temporary identifier RA-RNTI and the base station according to the index number preamble_id of the selected random access sequence and the index number f_id of the cluster where the synchronization subband is located Common subbands and radio frames for PDCCH grants;

b. The base station determines the RA-RNTI and the normal subband and subband used for PDCCH authorization according to the received index number preamble_id of the random access sequence and the index number f_id of the cluster where the synchronization subband is located radio frame: using the common subband and radio frame used for PDCCH authorization, perform PDCCH authorization to the UE, and send a random access response message carrying the RA-RNTI to the UE according to the PDCCH authorization;

c. If the UE monitors the PDCCH grant on the normal subband and radio frame used to send the random access response message, and receives the random access carrying the RA-RNTI according to the PDCCH grant Responding to a message, sending the information of the first uplink transmission to the base station, otherwise determining that the random access failed this time, and exiting the method;

d. The base station sends contention resolution information including the contention resolution identifier to the UE according to the received information of the first uplink transmission; if the UE successfully receives the contention resolution information during the start of the contention determination timer contention resolution information, it is determined that this random access is successful, otherwise it is determined that this random access fails.

To sum up, in the random access method proposed by the present invention, after the UE sends the random access pilot (Preamble) code on the physical random access channel (PRACH) resource, according to the index number preamble_id and The index number f_id of the cluster where the synchronization subband is used is used to determine the RA-RNTI and the common subband and radio frame used by the base station for physical downlink control channel PDCCH authorization, so as to jump to the radio frame and common subband to monitor random Access response. After receiving the Preamble code sent by the UE, the base station (eNB) also determines the radio frame and common subband used to send the random access response based on the same method as the UE. Receive the random access response message sent by the base station, so as to ensure that the UE supporting the single subband working mode can normally complete the random access process. system.

Description of drawings

FIG. 1 is a schematic diagram of a random access flow in an existing LTE system;

FIG. 2 is a schematic diagram of a traditional synchronous subband structure;

Fig. 3 is a schematic flow chart of Embodiment 1 of the present invention;

Fig. 4 is a schematic flow chart of Embodiment 2 of the present invention.

Detailed ways

In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

The core idea of the present invention is: based on the resource configuration characteristics of the broadband access system, the UE and the base station can determine the subband and radio frame used by the base station to send the random access response according to the information available to both parties, so that it can ensure The UE can receive the random access response message sent by the base station on the supported single subband, so as to ensure that the UE supporting the single subband working mode can normally complete the random access process.

FIG. 3 is a schematic flow chart of Embodiment 1 of the present invention. The random access method in Embodiment 1 mainly includes the following steps:

Step 301, the UE determines the synchronization subband used for the current random access, randomly selects one of the random access sequences corresponding to the cluster where the synchronization subband is located as the current random access sequence; The selected random access sequence is sent to the base station; according to the index number preamble_id of the selected random access sequence and the index number f_id of the cluster where the synchronization subband is located, determine the random access wireless network temporary identifier RA-RNTI and the base station Common subbands and radio frames used to send random access response messages.

What needs to be explained here is that in the existing broadband access system, the system usually clusters the subbands of each cell, and each cluster has at least one synchronous subband and several common subbands. For example, for typical applications Scenario 1 Electric load monitoring communication network, the system adopts the same frequency network, each cell has a total of 40 sub-bands and divides it into 3 clusters, in each cluster there is 1 synchronous sub-band, and the others are common sub-bands.

In practical applications, the UE can randomly select or determine the current synchronization subband used for random access according to the signal quality, specifically:

Selecting the synchronization subband with the largest reference signal received power from the synchronization subband resources supported by the UE as the synchronization subband used by the current random access;

Or, randomly select one of the synchronization subband resources supported by the UE as the synchronization subband used for the current random access.

Further, in order to improve the access success rate, on the basis of the above method, an idle synchronization subband access can be selected in conjunction with the busy indication about the cluster in the broadcast, specifically, the determination of the synchronization subband used for the current random access Belts can also be:

Selecting, from the synchronization subband resources supported by the UE, a synchronization subband with the highest reference signal received power and an idle synchronization subband as the synchronization subband used for the current random access;

Or, randomly select an idle synchronization subband from the synchronization subband resources supported by the UE as the synchronization subband used for the current random access.

Preferably, the RA-RNTI can be determined according to the formula RA-RNTI=R+preamble_id+N _preamble *f_id.

Among them, R is the preset identification starting position; N _preamble is the number of available random access sequences, 0<=preamble_id<N _preamble , N _preamble = min{N _{preamble_A} , T*N _{SERV_RB} }, N _{preamble_A} is based on The maximum number of random access sequences that can be obtained from the preamble preset by the network, T is the period of time division multiplexing of the physical random access channel PRACH resources of the same frequency cell, in units of radio frames, and N _{SERV_RB} is the location of the synchronization subband The number of common subbands within a cluster.

In this step, after the UE sends the random access sequence to the base station, it will determine the random access wireless network temporary identifier according to the index number preamble_id of the selected random access sequence and the index number f_id of the cluster where the synchronization subband is located RA-RNTI and the common subband and wireless frame used by the base station to send the random access response message. Similarly, the base station will use the same method to determine the random access wireless network temporary identifier RA after receiving the random access sequence - RNTI and common subbands and radio frames for sending random access response messages, so that the UE can receive the corresponding random access response sequence.

Preferably, the number of available random access sequences N _preamble can be determined according to the formula N _preamble =min{N _{preamble_A} , T*N _{SERV_RB} }, that is, when determining N _preamble , the total number of random access sequences should be considered on the one hand, On the one hand, it is also necessary to consider the number of subbands that the UE can use to monitor the random access response within a time division multiplexing period. In this way, it can support the unbalanced number of common subbands among cell subband clusters. The number of common subbands in the cluster supports as many preambles as possible, that is, supports as many UEs as possible to initiate random access at the same time.

Specifically, the normal subband for sending the random access response message may be determined according to SN=preamble_id mod N _{SERV_RB} , where SN is the relative subband number of the normal subband, and the relative subband number N _{SERV_RB} is the number of common subbands in the cluster where the synchronization subband is located.

Specifically, the radio frame used to send the random access response message may be according to the formula: Determine, wherein, TN is the index number of the radio frame, SFN _Msg1 is the radio frame number of the random access sequence sent by the UE, T _S is the preset random access response monitoring adjustment parameter, N _{SERV_RB} is The number of common subbands in the cluster where the synchronization subband is located.

Step 302, the base station determines the RA-RNTI and the RA-RNTI and the information used to send the random access response message according to the received index number preamble_id of the random access sequence and the index number f_id of the cluster where the synchronization subband is located. the normal subband and radio frame; sending the random access response message carrying the RA-RNTI to the UE by using the normal subband and radio frame used for sending the random access response message.

Here, the base station determines the RA-RNTI and the common subband and radio frame used to send the random access response message in the same method as in step 301 .

Step 303, if the UE monitors the random access response message carrying the RA-RNTI on the normal subband and radio frame used to send the random access response message, send the first uplink transmission information to the UE Otherwise, it is determined that the random access fails this time, and exits the method.

Step 304, the base station sends contention resolution information including the contention resolution identifier to the UE according to the received information of the first uplink transmission; if the UE successfully receives the contention resolution information during the start of the contention determination timer If the above contention resolution information is not used, it is determined that the random access is successful; otherwise, it is determined that the random access fails.

In the first embodiment above, the base station does not need to perform PDCCH authorization on the UE, but directly sends the random access response to the UE, which can save network resources and improve access efficiency. Of course, in practical application, the random access response message may also be sent by way of PDCCH authorization, so as to be compatible with the existing system, and the method will be further described through Embodiment 2 of the present invention below.

Embodiment 2 of the present invention mainly includes the following steps:

Step 401, the UE determines the synchronization subband used for the current random access, and randomly selects one of the random access sequences corresponding to the cluster where the synchronization subband is located as the current random access sequence; The selected random access sequence is sent to the base station; according to the index number preamble_id of the selected random access sequence and the index number f_id of the cluster where the synchronization subband is located, determine the random access wireless network temporary identifier RA-RNTI and the base station Common subbands and radio frames granted by the physical downlink control channel PDCCH.

In this step, the method of determining the synchronization subband used for the current random access and determining the RA-RNTI is the same as that of step 301, and will not be repeated here.

In this embodiment, both the UE and the base station will determine the common subband and radio frame used for PDCCH grant according to the preamble_id and f_id. Preferably, according to SN=preamble_id mod N _{SERV_RB} , determine the normal subband used for PDCCH authorization, where SN is the relative subband number of the normal subband, and the relative subband number is the All common subbands are sorted in ascending or descending order in the frequency domain, and N _{SERV_RB} is the number of common subbands in the cluster where the synchronization subband is located.

Preferably, the radio frame used for PDCCH grant can be formulated according to Obtained, wherein, TN is the radio frame number of the radio frame, SFN _Msg1 is the radio frame number of the random access sequence sent by the UE, T _S is the preset random access response monitoring adjustment parameter, N _{SERV_RB} is the number of common subbands in the cluster where the synchronization subband is located.

Step 402, the base station determines the RA-RNTI and the normal subband used for PDCCH authorization according to the received index number preamble_id of the random access sequence and the index number f_id of the cluster where the synchronization subband is located and a radio frame: performing PDCCH authorization to the UE by using the common subband and radio frame used for PDCCH authorization, and sending a random access response message carrying the RA-RNTI to the UE according to the PDCCH authorization.

Step 403, if the UE monitors the PDCCH grant on the normal subband and radio frame used to send the random access response message, and receives the random access request carrying the RA-RNTI according to the PDCCH grant If a response message is received, the first uplink transmission information is sent to the base station; otherwise, it is determined that the random access fails this time, and the method is exited.

Step 404, the base station sends contention resolution information including the contention resolution identifier to the UE according to the received information of the first uplink transmission; if the UE successfully receives the contention resolution information during the start of the contention determination timer If the above contention resolution information is not used, it is determined that the random access is successful; otherwise, it is determined that the random access fails.

To sum up, the above are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (12)

1. accidental access method, this method is characterized in that to the user equipment (UE) of supporting list band mode of operation this method may further comprise the steps:

A, user equipment (UE) are confirmed the current employed synchronous subband that inserts at random, in bunch corresponding random access sequence of said synchronous subband place, select one at random as current random access sequence; On said synchronous subband, selected random access sequence is sent to the base station; Call number f_id according to the call number preamble_id of selected random access sequence and said synchronous subband place bunch confirms that random access radio network temporary mark RA-RNTI and base station are used to send the common subband and the radio frames of accidental access response message;

B, said base station confirm said RA-RNTI and said common subband and the radio frames that is used to send accidental access response message according to the call number f_id at the call number preamble_id of the said random access sequence that receives and said synchronous subband place bunch; Utilize said common subband and the radio frames that is used to send accidental access response message, send the accidental access response message that carries said RA-RNTI to said UE;

If the said UE of c listens to the accidental access response message that carries said RA-RNTI on said common subband that is used to send accidental access response message and radio frames; Then send the information of uplink first and give said base station; Otherwise confirm this access failure at random, withdraw from said method;

The information of the said uplink first that d, said base station basis receive is sent the competition that includes said competition resolution sign to said UE and is solved information; If said UE successfully receives said competition at competition judgement timer and solves information between the starting period, confirm that then this inserts success at random, otherwise confirm this access failure at random.

2. method according to claim 1 is characterized in that, according to RA-RNTI=R+preamble_id+N _Preamble* f_id confirms said RA-RNTI, and wherein, R is preset sign original position, N _PreambleBe available random access sequence number, 0＜=preamble_id＜N _Preamble, N _Preamble=min{N _{Preamble_A}, T*N _{SERV_RB}, N _{Preamble_A}Be the lead code available largest random access sequence number preset according to network, T is the time-multiplexed cycle of Physical Random Access Channel PRACH resource of co-frequency cell, is unit with the radio frames, N _{SERV_RB}Be the common number of sub-bands in the said synchronous subband place bunch.

3. method according to claim 1 is characterized in that, according to SN=preamble_id mod N _{SERV_RB}, confirm the said common subband that is used to send accidental access response message, wherein, SN is the sub-relatively reel number of said common subband, said sub-relatively reel number be in the subband bunch all common subbands at the sequence number that obtains after with ascending order or descending on the frequency domain, N _{SERV_RB}Be the common number of sub-bands in the said synchronous subband place bunch.

4. method according to claim 1 is characterized in that, according to

Confirm to be used to send the radio frames of accidental access response message, wherein, TN is the call number of said radio frames, SFN _Msg1Be the radio frame number that said UE sends selected random access sequence, T _SBe that the accidental access response of presetting is monitored adjustment parameter, N _{SERV_RB}Be the common number of sub-bands in the said synchronous subband place bunch.

5. method according to claim 1 is characterized in that, saidly confirms currently to insert employed synchronous subband at random and be:

From the synchronous sub band resources that said UE supports, select the maximum synchronous subband of Reference Signal Received Power to insert employed synchronous subband at random as current;

Perhaps, from the synchronous sub band resources that said UE supports, select one to insert employed synchronous subband at random at random as current.

6. method according to claim 1 is characterized in that, saidly confirms currently to insert employed synchronous subband at random and be:

From the synchronous sub band resources that said UE supports, select the maximum and idle synchronous subband of Reference Signal Received Power to insert employed synchronous subband at random as current;

Perhaps, the synchronous subband of from the synchronous sub band resources that said UE supports, selecting a free time at random inserts employed synchronous subband at random as current.

7. accidental access method, this method is characterized in that to the user equipment (UE) of supporting list band mode of operation this method may further comprise the steps:

A, user equipment (UE) are confirmed the current employed synchronous subband that inserts at random, in bunch corresponding random access sequence of said synchronous subband place, select one at random as current random access sequence; On said synchronous subband, selected random access sequence is sent to the base station; Call number f_id according to the call number preamble_id of selected random access sequence and said synchronous subband place bunch confirms that random access radio network temporary mark RA-RNTI and base station are used for the common subband and the radio frames of physical downlink control channel PDCCH mandate;

B, said base station confirm common subband and radio frames that said RA-RNTI and the said PDCCH of being used for authorize according to the call number f_id at the call number preamble_id of the said random access sequence that receives and said synchronous subband place bunch; Common subband and the radio frames of utilizing the said PDCCH of being used for to authorize are carried out PDCCH to said UE and are authorized, and give said UE according to the accidental access response message that said PDCCH authorizes transmission to carry said RA-RNTI;

If the said UE of c listens to said PDCCH and authorizes on said common subband that is used to send accidental access response message and radio frames; And authorize according to said PDCCH and to receive the accidental access response message that carries said RA-RNTI; Then send the information of uplink first and give said base station; Otherwise confirm this access failure at random, withdraw from said method;

The information of the said uplink first that d, said base station basis receive is sent the competition that includes said competition resolution sign to said UE and is solved information; If said UE successfully receives said competition at competition judgement timer and solves information between the starting period, confirm that then this inserts success at random, otherwise confirm this access failure at random.

8. method according to claim 7 is characterized in that, according to RA-RNTI=R+preamble_id+N _Preamble* f_id confirms said RA-RNTI, and wherein, R is preset sign original position, N _PreambleBe available random access sequence number, 0＜=preamble_id＜N _Preamble, N _Preamble=min{N _{Preamble_A}, T*N _{SERV_RB}, N _{Preamble_A}Be the lead code available largest random access sequence number preset according to network, T is the time-multiplexed cycle of Physical Random Access Channel PRACH resource of co-frequency cell, is unit with the radio frames, N _{SERV_RB}Be the common number of sub-bands in the said synchronous subband place bunch.

9. method according to claim 7 is characterized in that, according to SN=preamble_id mod N _{SERV_RB}, confirm the common subband that the said PDCCH of being used for authorizes, wherein, SN is the sub-relatively reel number of said common subband, said sub-relatively reel number be in the subband bunch all common subbands at the sequence number that obtains after with ascending order or descending on the frequency domain, N _{SERV_RB}Be the common number of sub-bands in the said synchronous subband place bunch.

10. method according to claim 7 is characterized in that, according to

Confirm to be used for the radio frames that PDCCH authorizes, wherein, TN is the radio frame number of said radio frames, SFN _Msg1Be the radio frame number that said UE sends selected random access sequence, T _SBe that the accidental access response of presetting is monitored adjustment parameter, N _{SERV_RB}Be the common number of sub-bands in the said synchronous subband place bunch.

11. method according to claim 7 is characterized in that, saidly confirms currently to insert employed synchronous subband at random and be:

From the synchronous sub band resources that said UE supports, select the maximum synchronous subband of Reference Signal Received Power to insert employed synchronous subband at random as current;

Perhaps, from the synchronous sub band resources that said UE supports, select one to insert employed synchronous subband at random at random as current.

12. method according to claim 7 is characterized in that, saidly confirms currently to insert employed synchronous subband at random and be:

From the synchronous sub band resources that said UE supports, select the maximum and idle synchronous subband of Reference Signal Received Power to insert employed synchronous subband at random as current;

Perhaps, the synchronous subband of from the synchronous sub band resources that said UE supports, selecting a free time at random inserts employed synchronous subband at random as current.

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