CN102271418A

CN102271418A - Random access method and device

Info

Publication number: CN102271418A
Application number: CN2011102141918A
Authority: CN
Inventors: 高雪娟; 林亚男; 许芳丽; 沈祖康
Original assignee: China Academy of Telecommunications Technology CATT
Current assignee: China Academy of Telecommunications Technology CATT; Datang Mobile Communications Equipment Co Ltd
Priority date: 2011-07-28
Filing date: 2011-07-28
Publication date: 2011-12-07
Anticipated expiration: 2031-07-28
Also published as: CN102271418B

Abstract

The invention discloses a random access method, which is used for realizing a random access process to realize uplink synchronization between a user side and a network side on the basis of not increasing the physical downlink control channel (PDCCH) blind detection of user equipment (UE). The method comprises that: the UE receives random access configuration information, and determines a dedicated preamble sequence and dedicated physical random access channel (PRACH) resources used by a cell required to perform random access according to the configuration information; the UE transmits the dedicated preamble sequence to an evolved NodeB (eNB) by the dedicated PRACH resources; and the UE detects a PDCCH scrambled by adopting a random access-radio network temporary identifier (RA-RNTI) in a dedicated searching space, and acquires a random access response to the PDCCH, wherein the random access response at least comprises a time alignment (TA) used for regulating the uplink synchronization of the cell transmitting the dedicated preamble sequence. The invention also discloses a device for implementing the method.

Description

Random access method and device

Technical Field

The present invention relates to the field of communications, and in particular, to a method and an apparatus for random access.

Background

A Random Access procedure (Random Access procedure) is used to establish uplink synchronization between a User Equipment (UE) and a base station (eNB), and a PRACH (Physical Random Access Channel) is used to send a Random Access preamble sequence in an uplink subframe configured in a system for Random Access and receive a Random Access Response (RAR) fed back by the base station to implement uplink synchronization. The random access procedure is divided into contention random access and non-contention random access.

Non-contention random access procedure as shown in fig. 1, it includes: and the UE receives a message (Msg0) sent by the eNB for configuring the dedicated preamble and PRACH resource used by the non-contention random access. The Msg0 contains at least ra-preamble index (random Access preamble) and ra-PRACH-maskindex (PRACH Mask index). The ra-preamble index is used for indicating the number of the special preamble, and the ra-PRACH-MaskIndex is used for indicating the number of the PRACH resource. And the UE sends the configured special preamble sequence (Msg1) to the eNB on the corresponding PRACH resource according to the PRACH resource number. The UE receives an RAR (Msg2) returned by the eNB through a PDSCH (Physical Downlink Shared Channel), wherein the RAR is scheduled by an RA-RNTI (random access-Radio Network Temporary Identifier) and transmitted on a PDSCH scheduled by the PDCCH, the PDSCH may include RARs of multiple UEs, and the RAR of each UE includes a TA value and an uplink scheduling grant (UL grant) for scheduling Msg3 transmission (or subsequent uplink transmission) of the UE. RA-RANTI corresponds to PRACH resources one by one, one PRACH resource only corresponds to one RA-RNTI, and RA-RNTI is 1+ t _ id +10 f _ id, wherein: t _ id is the number of the first subframe corresponding to the PRACH resource, and the value of t _ id is more than or equal to 0 and less than 10; f _ id is the number of PRACH resources in a subframe in the frequency domain, and is numbered according to the ascending order of the frequency domain, and the value is (f _ id is more than or equal to 0 and less than 6). The UE that has sent the preamble needs to monitor the PDCCH scrambled by the RA-RNTI in the RAR receiving window defined by the system, and if it is detected that the RAR includes the preamble identifier sent by the UE, the UE considers that the RAR is successfully received, and performs uplink synchronization adjustment by using a TA (Time Alignment, timing advance) carried in the RAR, which indicates that the random access is successful, and the random access process is ended.

The PRACH resources need to be determined before the UE sends Msg 1. In the LTE (Long Term Evolution) system, 5 prach (preamble) structures are defined, and each structure has a difference in length in the time domain, and as shown in table 1, occupies 6 PRB (Physical resource blocks) (i.e., 72 subcarriers) in the frequency domain. For FDD (Frequency Division Duplex) systems, there is at most one PRACH within a subframe. For a TDD (Time division duplex) system, there are at most 6 PRACH channels in a subframe for frequency division multiplexing. According to the transmission density and preamble format of the PRACH, 64 PRACH configurations are defined in the FDD system, 58 PRACH configurations are defined in the TDD system, each PRACH Configuration corresponds to one preamble format used in the system and a subframe set that can be used to transmit the PRACH in one radio frame, and a higher layer signaling informs the UE of the PRACH Configuration Index (PRACH Configuration Index) used.

TABLE 1 Preamble parameters

As can be seen from the above procedure, in Msg2, RARs transmitted by eNB through PDSCH all need to be scheduled through PDCCH and transmitted on PDSCH.

For an LTE-a (Long Term Evolution Advanced) system, in order to support a system bandwidth larger than that of the LTE (Long Term Evolution), some frequency spectrums allocated to the existing system may be aggregated and used as a large bandwidth, that is, Carrier Aggregation (CA). At this time, the uplink and downlink carriers in the system may be configured asymmetrically, that is, the user may occupy N1 ≧ 1(N1 is a preset parameter) carriers for downlink transmission, and N2 ≧ 1(N2 is a preset parameter) carriers for uplink transmission, as shown in fig. 2.

In the LTE-a Rel-10 (release 10) CA system, only continuous carrier aggregation is supported in the uplink direction, and each UE is allocated one Pcell (Primary cell) by the base station: for FDD systems, a Cell contains one downlink carrier and one uplink carrier, and for TDD systems, a carrier becomes a Cell. In LTE-A Rel-10, random access of CA UE only occurs on Pcell, and all cells use the same TA to perform uplink synchronization adjustment. The UE only needs to blindly detect the common search space on the PCell to determine the PDCCH for scheduling RAR. On an SCell (Secondary cell), the UE only needs to blindly detect a UE-specific search space to acquire a PDCCH for data scheduling. For the UE capability of Rel-10, the blind detection of the common search space on the SCell is not included in the design of the physical layer PDCCH blind detection times of the CA UE.

Unlike the LTE-a Rel-10 system, the LTE-a Rel-11 (release 11) system needs to support more complex carrier aggregation scenarios, including: 1) carrier aggregation of different uplink frequency bands; 2) a carrier aggregation deployment scheme with a mixture of Macro base stations (Macro enbs) and RRHs (Remote Radio heads). Examples of carrier aggregation deployment scenarios in which macro base stations and RRHs are mixed are shown in fig. 3 and 4. For fig. 3, frequency F1 is used by the macro base station, providing macro coverage, and frequency F2 is used by the RRHs, providing higher throughput for hot spot areas. The UE moving at high speed operates on the frequency of F1, ensuring continuous traffic. The frequencies of F1 and F2 are different, for example, F1 is located at 800MHz or 2GHz frequency band, and F2 is located at 3.5GHz frequency band. Within the geographic area covered by the F2 RRH, F2 may perform carrier aggregation with F1. For fig. 4, the frequencies F1 and F2 are used by the macro base station, and for the frequency band reason, F2 has a smaller coverage area than F1, so that RRHs are deployed at the cell edge of F2 for coverage extension. In the region where the F1 and the F2 cover the overlap, F1 and F2 may perform carrier aggregation.

Since the propagation characteristics of wireless signals in different frequency bands are different, if the UE transmits signals to the base station on the component carriers located in two frequency bands at a longer distance, the arrival times of the two signals at the base station will be different. Furthermore, according to the examples in fig. 3 and 4, if the UE is in a geographical area covered by both the macro base station and the RRH, and carrier aggregation of F1 and F2 is performed, since F1 is used by the macro base station and F2 is used by the RRH, signals on two frequencies travel different propagation paths, resulting in a difference in arrival times of the signals transmitted simultaneously by the UE on F1 and F2 at the base station. Therefore, in carrier aggregation in different frequency bands or a carrier aggregation deployment scenario in which a macro base station and an RRH are mixed, transmission times are different due to different Pcell and Scell signal paths, and a plurality of Cell cells need to independently establish and maintain uplink synchronization with the base station, so that random access on the Scell needs to be supported to achieve uplink synchronization adjustment. At present, the standard does not define the random access mode of the above scenario.

Disclosure of Invention

The embodiment of the invention provides a random access method and a random access device, which are used for realizing a random access process, in particular realizing the random access process on an auxiliary cell, so that a user side and a network side can realize uplink synchronization without increasing blind detection of a PDCCH (physical downlink control channel) by UE (user equipment).

A random access method is applied to a UE side and comprises the following steps:

the method comprises the steps that User Equipment (UE) receives random access configuration information sent by a base station, and determines an exclusive random access preamble sequence used on a cell needing random access and an exclusive Physical Random Access Channel (PRACH) resource used for sending the exclusive preamble sequence according to the configuration information;

the UE sends the exclusive preamble sequence to a base station through the determined exclusive PRACH resource on a cell needing random access;

the UE detects a Physical Downlink Control Channel (PDCCH) scrambled by a random access radio network temporary identifier (RA-RNTI) in a special search space of the UE, and obtains a random access response of the cell which sends the special preamble sequence from the PDCCH, wherein the random access response at least comprises a Timing Advance (TA) used for uplink synchronous adjustment of the cell which sends the special preamble sequence.

A random access method is applied to a base station side and comprises the following steps:

a base station sends random access configuration information to User Equipment (UE) and configures an exclusive random access preamble sequence and an exclusive Physical Random Access Channel (PRACH) resource for a cell of the UE which needs to carry out random access;

the base station receives an exclusive preamble sequence sent by the UE on an exclusive PRACH resource configured to the UE;

the base station determines a timing advance TA value corresponding to a cell receiving the dedicated preamble sequence according to the received dedicated preamble sequence;

and the base station sends a random access response to the UE in a special search space of the UE through a physical downlink control channel PDCCH scrambled by a random access radio network temporary identifier RA-RNTI, wherein the random access response at least comprises a TA (timing advance) used for uplink synchronization adjustment of the cell receiving the exclusive preamble sequence.

A user equipment, comprising:

a receiving module, configured to receive random access configuration information sent by a base station;

the control module is used for determining an exclusive random access preamble sequence used on a cell needing random access and an exclusive Physical Random Access Channel (PRACH) resource used for sending the exclusive preamble sequence according to the configuration information;

a sending module, configured to send the dedicated preamble sequence to a base station through the determined dedicated PRACH resource on a cell that needs to be randomly accessed;

the receiving module is further configured to detect a physical downlink control channel PDCCH scrambled by a random access radio network temporary identifier RA-RNTI in the dedicated search space of the UE, and obtain a random access response of the cell that has sent the dedicated preamble sequence from the PDCCH, where the random access response at least includes a timing advance TA for uplink synchronization adjustment of the cell that has sent the dedicated preamble sequence.

A base station, comprising:

a sending module, configured to send random access configuration information to a user equipment UE, and configure an exclusive random access preamble sequence and an exclusive physical random access channel PRACH resource for a cell of the UE that needs to perform random access;

a receiving module, configured to receive an exclusive preamble sequence sent by the UE on an exclusive PRACH resource configured to the UE;

the control module is used for determining a timing advance TA value corresponding to a cell receiving the exclusive preamble sequence according to the received exclusive preamble sequence;

the sending module is further configured to send a random access response to the UE in the dedicated search space of the UE through a physical downlink control channel PDCCH scrambled by a random access radio network temporary identifier RA-RNTI, where the random access response at least includes a TA used for uplink synchronization adjustment of the cell receiving the dedicated preamble sequence.

In the embodiment of the invention, the random access response is transmitted by using the Physical Downlink Control Channel (PDCCH) scrambled by the random access radio network temporary identifier (RA-RNTI) in the special search space of the UE, the random access process is realized, the random access method is particularly suitable for the SCell, the PDCCH scrambled by the RA-RNTI is transmitted in the special search space of the UE, the blind detection times of the UE on the PDCCH are not increased, the random access response is not required to be transmitted on the PDSCH, the PDSCH transmission scheduled by the PDCCH scrambled by the RA-RNTI on the SCell is avoided, and compared with the transmission of the random access response on the PDSCH scheduled by the PDCCH scrambled by the RA-RNTI, the overhead of downlink data transmission is saved to a certain extent.

Drawings

Fig. 1 is a flow chart of a method of non-contention random access in the prior art;

FIG. 2 is a diagram of spectrum aggregation in the prior art;

fig. 3 and 4 are schematic diagrams of a hybrid deployment of a macro base station and an RRH in the prior art;

FIG. 5 is a flowchart of a method for random access at a UE side according to an embodiment of the present invention;

fig. 6 is a flowchart of a method for random access at a base station side according to an embodiment of the present invention;

FIG. 7 is a flowchart of a method for random access without cross-carrier scheduling according to an embodiment of the present invention;

FIG. 8 is a flowchart of a method for random access during cross-carrier scheduling according to an embodiment of the present invention;

FIG. 9 is a diagram illustrating a UE according to an embodiment of the present invention;

fig. 10 is a block diagram of a base station in an embodiment of the present invention.

Detailed Description

Referring to fig. 5, the flow of the method for randomly accessing to the UE side in this embodiment is as follows:

step 501: the UE receives random access configuration information sent by a base station, and determines an exclusive random access preamble (preamble) sequence used on a cell needing random access and an exclusive Physical Random Access Channel (PRACH) resource used for sending the exclusive preamble sequence according to the configuration information. Specifically, the UE receives random access configuration information sent by a base station through a PDCCH order (order) or Radio Resource Control (RRC) signaling, where the random access configuration information at least includes index information of an exclusive preamble sequence of a cell that needs to be randomly accessed and index information of an exclusive PRACH resource, and the index information is configured to the UE.

Step 502: and the UE sends the exclusive preamble sequence to a base station through the determined exclusive PRACH resource on a cell needing random access.

Step 503: the UE detects a Physical Downlink Control Channel (PDCCH) scrambled by a random access radio network temporary identifier (RA-RNTI) in a special search space of the UE, and obtains a random access response of the cell which sends the exclusive preamble sequence from the PDCCH. The random access response at least comprises a Timing Advance (TA) used for uplink synchronization adjustment of the cell which sends the exclusive preamble sequence. The UE may perform uplink synchronization adjustment according to the TA value.

Preferably, the random access response further includes an uplink scheduling grant UL grant signaling corresponding to the cell that sent the dedicated preamble sequence.

And the UE detects the PDCCH scrambled by the RA-RNTI in a special search space of the UE on the cell which corresponds to the cell which sends the special preamble sequence and is used for transmitting the scheduling signaling of the cell.

And when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the cell for transmitting the scheduling signaling corresponding to the cell which sends the exclusive preamble sequence and the cell which sends the exclusive preamble sequence are the same cell. Then, the UE detects the PDCCH scrambled by the RA-RNTI in a special search space of the UE on the cell which sends the special preamble sequence, and the random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to the cell where the PDCCH scrambled by the RA-RNTI is transmitted. For example, the UE sends an exclusive preamble sequence on the cell 1, and the scheduling signaling of the cell 1 is sent on the cell 1, so that the UE detects the PDCCH scrambled by the RA-RNTI in the UE-dedicated search space of the cell 1, and obtains the TA corresponding to the cell 1 from the PDCCH; the random access response carried in the PDCCH scrambled by the RA-RNTI detected by the UE on the cell 1 is the random access response of the cell 1.

When the PDCCH scrambled by the RA-RNTI employs cross-carrier scheduling, a cell for transmitting the scheduling signaling corresponding to the cell that sends the dedicated preamble sequence and the cell that sends the dedicated preamble sequence may be different cells. Then, the UE detects the PDCCH scrambled by the RA-RNTI in a dedicated search space of the UE on the cell performing cross-carrier scheduling on the cell which sends the exclusive preamble sequence, and the random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to the cell indicated by the carrier indication field carried in the PDCCH scrambled by the RA-RNTI. For example, the UE sends an exclusive preamble sequence in cell 2 and cell 3, and the scheduling information of cell 2 and cell 3 is sent on cell 1, so that the UE detects the PDCCH scrambled by RA-RNTI in the UE-dedicated search space of cell 1, and obtains the TAs corresponding to cell 1 and cell 2; the random access response carried in the PDCCH scrambled by a plurality of RA-RNTIs detected by the UE on the cell corresponds to the cell 2 or the cell 3 and is indicated by a carrier indication domain carried in the PDCCH.

It should be noted that, the UE-specific search space specifically refers to a cell used for transmitting the scheduling signaling of the cell that sends the dedicated preamble sequence, and a part of the UE-specific search space corresponds to the cell that sends the dedicated preamble sequence.

Preferably, the PDCCH scrambled by the RA-RNTI adopts a DCI format (format) supported by a transmission mode of the cell that sends the dedicated preamble sequence, where the DCI format includes a DCI format for carrying an uplink scheduling grant UL grant and a DCI format for carrying a downlink scheduling grant DL grant.

If the random access response carried in the PDCCH scrambled by the RA-RNTI only contains a TA command, when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K, and the K is the bit number of the TA command corresponding to the cell which sends the exclusive preamble sequence. When the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K + A, the K is the bit number of the TA command corresponding to the cell which sends the exclusive preamble sequence, and the A is the bit number of a carrier indication domain in the PDCCH scrambled by the RA-RNTI. Preferably, K is 11 and a is 3. For example, if K is 11 and a is 3, then for FDD and TDD systems: all currently defined DCI formats for carrying UL and DL grants transmitted in the UE-specific search space may be used, for example, DCI format 0/1/1 a/1B/2/2A/2B/2C/4; i.e. the DCI format supported in the transmission mode of the cell that sent the dedicated preamble sequence, may be used to transmit the random access response.

Or, if the random access response carried in the PDCCH scrambled by the RA-RNTI includes both a TA command and a UL grant, when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the DCI format is a DCI format carrying a number of bits not less than K + L, where K is the number of bits of the TA command corresponding to the cell that has sent the dedicated preamble sequence, and L is the number of bits of the UL grant corresponding to the cell that has sent the dedicated preamble sequence. When the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K + L + A, the K is the bit number of the TA command corresponding to the cell which sends the exclusive preamble sequence, the L is the bit number of the UL grant corresponding to the cell which sends the exclusive preamble sequence, and the A is the bit number of a carrier indication domain in the PDCCH scrambled by the RA-RNTI. Preferably, K is 11, L is 20, and a is 3. For example, if K is 11, L is 20, and a is 3, then for a TDD system (regardless of whether cross-carrier scheduling is employed), the available DCI format includes: DCI format 0 (the uplink bandwidth applicable to the cell is not less than 20MHz), DCI format1/1B/1D (the downlink bandwidth applicable to the cell is not less than 10MHz), DCI format 1A (the downlink bandwidth applicable to the cell is not less than 20MHz), DCI format 2/2A/2B/2C (any bandwidth of the cell can be used), and DCI format 4 (the uplink bandwidth applicable to the cell is not less than 3 MHz); for FDD systems (whether or not cross-carrier scheduling is employed), the available DCI formats include: DCI format1 (downlink bandwidth applicable to the cell is not less than 10MHz), DCI format 2 (any bandwidth of the cell can be used), DCI format 2A/2C (downlink bandwidth applicable to the cell is not less than 3MHz), DCI format 2B (downlink bandwidth applicable to the cell is not less than 5MHz), and DCI format 4 (uplink bandwidth applicable to the cell is not less than 5 MHz); that is, in the DCI format supported in the transmission mode of the cell that transmits the dedicated preamble sequence, the DCI format satisfying the above condition may be used to transmit the random access response.

Preferably, the cell requiring random access and/or the cell sending the dedicated preamble sequence in this embodiment are/is the secondary cell of the UE, and the random access scheme provided in this embodiment is particularly suitable for the secondary cell, and certainly does not exclude the application to the primary cell. The PRACH configuration on each Scell may be the same as or different from the Pcell. Specifically, when a plurality of cells are defined in the system as a TA group (group) sharing one TA, the cell may also refer to one cell of predefined (UE pre-agreed with the base station) or signaling configuration (higher layer signaling or PDCCH signaling, where the higher layer signaling may include Radio Resource Control (RRC) signaling or Medium Access Control (MAC) signaling) in at least one cell included in the TA group sharing one TA, and for cells belonging to the same TA group, the UE only needs to perform the random access procedure on one cell of the predefined or signaling configuration to obtain a TA value, and apply the TA to all cells belonging to the TA group.

Preferably, in this embodiment, the UE detects the PDCCH scrambled by the RA-RNTI in a dedicated search space of the UE only within a system-defined random access response reception window (RARwindow); if the random access exceeds the RAR window and the UE still does not receive the PDCCH scrambled by the RA-RNTI, the UE can consider that the random access fails and resend the exclusive preamble sequence of the cell.

In contrast to the UE side, referring to fig. 6, the flow of the method for randomly accessing to the base station side in this embodiment is as follows:

step 601: the base station sends random access configuration information to User Equipment (UE), and configures a dedicated random access preamble (preamble) sequence and a dedicated Physical Random Access Channel (PRACH) resource for a cell of the UE which needs to perform random access. Specifically, the base station sends random access configuration information to the UE through a PDCCH order or a radio resource control RRC signaling, where the random access configuration information at least includes index information of a dedicated random access preamble (preamble) sequence configured to the UE and index information of a dedicated Physical Random Access Channel (PRACH) resource.

Step 602: and the base station receives an exclusive preamble sequence sent by the UE on an exclusive PRACH resource configured to the UE.

Step 603: and the base station determines a Timing Advance (TA) value corresponding to the cell receiving the dedicated preamble sequence according to the received dedicated preamble sequence.

Step 604: and the base station sends a random access response to the UE in the special search space of the UE through a Physical Downlink Control Channel (PDCCH) scrambled by a random access radio network temporary identifier (RA-RNTI), wherein the random access response at least comprises a TA (timing advance) used for uplink synchronous adjustment of the cell receiving the special preamble sequence.

And the base station sends a random access response to the UE through the PDCCH scrambled by the RA-RNTI in a special search space of the UE on the cell which corresponds to the cell receiving the exclusive preamble sequence and is used for transmitting the scheduling signaling of the cell.

And when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the cell for transmitting the scheduling signaling corresponding to the cell receiving the exclusive preamble sequence and the cell receiving the exclusive preamble sequence are the same cell. Then, the base station sends a random access response to the UE through the PDCCH scrambled by the RA-RNTI in a dedicated search space of the UE on the cell receiving the dedicated preamble sequence, wherein the random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to the cell where the PDCCH scrambled by the RA-RNTI is transmitted. For example, when the base station receives an exclusive preamble sequence on the cell 1, and the scheduling signaling of the cell 1 is sent on the cell 1, the base station transmits a PDCCH scrambled by an RA-RNTI in a dedicated search space of the UE of the cell 1, and sends a TA corresponding to the cell 1 to the UE; the random access response carried in the PDCCH scrambled by the RA-RNTI transmitted in the cell 1 is the random access response of the cell 1.

When the PDCCH scrambled by the RA-RNTI employs cross-carrier scheduling, a cell for transmitting the scheduling signaling corresponding to the cell receiving the dedicated preamble sequence and the cell receiving the dedicated preamble sequence may be different cells. Then, the base station transmits the PDCCH scrambled by the RA-RNTI in a dedicated search space of the UE on a cell performing cross-carrier scheduling on the cell receiving the dedicated preamble sequence, wherein a random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to a cell indicated by a carrier indication field carried in the PDCCH scrambled by the RA-RNTI.

Preferably, the PDCCH scrambled by the RA-RNTI adopts a DCI format (format) supported by a transmission mode of the cell receiving the dedicated preamble sequence, where the DCI format includes a DCI format for carrying an uplink scheduling grant (UL grant) and a DCI format for carrying a downlink scheduling grant (DLgrant).

If the random access response carried in the PDCCH scrambled by the RA-RNTI only contains a TA command, when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K, and the K is the bit number of the TA command corresponding to the cell which sends the exclusive preamble sequence. When the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K + A, the K is the bit number of the TA command corresponding to the cell which sends the exclusive preamble sequence, and the A is the bit number of a carrier indication domain in the PDCCH scrambled by the RA-RNTI. Preferably, K is 11 and a is 3. For example, if K is 11 and a is 3, then for FDD and TDD systems: all currently defined DCI formats for carrying UL and DL grants transmitted in the UE-specific search space may be used, for example, DCI format 0/1/1 a/1B/2/2A/2B/2C/4; that is, the DCI format supported in the transmission mode of the cell receiving the dedicated preamble sequence may be used to transmit the random access response.

Preferably, the cell requiring random access and/or the cell sending the dedicated preamble sequence in this embodiment are/is the secondary cell of the UE, and the random access scheme provided in this embodiment is particularly suitable for the secondary cell, and certainly does not exclude the application to the primary cell. The PRACH configuration on each Scell may be the same as or different from the Pcell. Specifically, when a plurality of cells are defined in the system as a TA group (group) sharing one TA, the cell may also refer to one cell of predefined (UE pre-agreed with the base station) or signaling configuration (higher layer signaling or PDCCH signaling, where the higher layer signaling may include Radio Resource Control (RRC) signaling or Medium Access Control (MAC) signaling) in at least one cell included in the TA group sharing one TA, and for cells belonging to the same TA group, the base station only needs to perform the above random access procedure on one cell of the predefined or signaling configuration, and send a TA value, which is applicable to all cells belonging to the TA group.

Since there are two cases of cross-carrier scheduling and non-cross-carrier scheduling, the implementation process is described in detail below by two exemplary embodiments.

Referring to fig. 7, the flow of the random access method when scheduling without cross carrier in the embodiment is as follows:

step 701: and the base station sends the random access configuration information to the UE through the PDCCH order or RRC signaling. The random access configuration information at least comprises index information of an exclusive preamble sequence configured to the UE and index information of an exclusive PRACH resource.

Step 702: after receiving the random access configuration information, the UE determines an exclusive preamble sequence used on a cell needing random access and an exclusive PRACH resource used for sending the exclusive preamble sequence according to the configuration information.

Step 703: and the UE sends the exclusive preamble sequence to the base station through the determined exclusive PRACH resource on the cell needing random access.

Step 704: after receiving the exclusive preamble sequence, the base station determines a TA value corresponding to the cell receiving the exclusive preamble sequence according to the received exclusive preamble sequence.

Step 705: and the base station sends a random access response to the UE in a special search space of the UE on the cell receiving the special preamble sequence through a PDCCH scrambled by an RA-RNTI, wherein the random access response at least comprises a TA (timing advance) used for uplink synchronization adjustment of the cell receiving the special preamble sequence. And the random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to the cell receiving the special preamble sequence. When the random access response only comprises a TA (timing advance) for uplink synchronization adjustment of the cell receiving the dedicated preamble sequence, the DCI format adopted by the PDCCH is a DCI format with the carrying bit number not less than K, and the K is the bit number of the TA command corresponding to the cell receiving the dedicated preamble sequence; or, when the random access response further includes an uplink scheduling grant (UL grant) signaling corresponding to the cell receiving the dedicated preamble sequence, the DCI format adopted by the PDCCH is a DCI format with a carrying bit number not less than K + L, where K is the bit number of the TA command corresponding to the cell receiving the dedicated preamble sequence, and L is the bit number of the UL grant corresponding to the cell receiving the dedicated preamble sequence.

Step 706: and the UE detects the PDCCH scrambled by the RA-RNTI in a special search space of the UE on the cell which sends the special preamble sequence. And the random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to the cell which sends the special preamble sequence.

Referring to fig. 8, the flow of the method for random access during cross-carrier scheduling in this embodiment is as follows:

step 801: and the base station sends the random access configuration information to the UE through the PDCCH order or RRC signaling. The random access configuration information at least comprises index information of an exclusive preamble sequence configured to the UE and index information of an exclusive PRACH resource.

Step 802: after receiving the random access configuration information, the UE determines an exclusive preamble sequence used on a cell needing random access and an exclusive PRACH resource used for sending the exclusive preamble sequence according to the configuration information.

Step 803: and the UE sends the exclusive preamble sequence to the base station through the determined exclusive PRACH resource on the cell needing random access.

Step 804: after receiving the exclusive preamble sequence, the base station determines a TA value corresponding to the cell receiving the exclusive preamble sequence according to the received exclusive preamble sequence.

Step 805: and the base station sends a random access response to the UE through a PDCCH scrambled by an RA-RNTI in a special search space of the UE on a cell which corresponds to the cell receiving the special preamble sequence and is used for transmitting a scheduling signaling of the cell, wherein the random access response at least comprises a TA (timing advance) used for uplink synchronization adjustment of the cell receiving the special preamble sequence. And the random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to a cell indicated by a carrier indication field carried in the PDCCH scrambled by the RA-RNTI.

When the random access response only comprises a TA (timing advance) for uplink synchronization adjustment of a cell receiving an exclusive preamble sequence, a DCI format adopted by the PDCCH is a DCI format with the carrying bit number not less than K + A, wherein K is the bit number of a TA command corresponding to the cell receiving the exclusive preamble sequence, and A is the bit number of a carrier indication domain in the PDCCH scrambled by RA-RNTI. Or, when the random access response further includes an uplink scheduling grant (UL grant) signaling corresponding to a cell receiving an exclusive preamble sequence, the DCI format adopted by the PDCCH is a DCI format with a carrying bit number not less than K + L + A, where K is the bit number of a TA command corresponding to the cell receiving the exclusive preamble sequence, L is the bit number of the UL grant corresponding to the cell receiving the exclusive preamble sequence, and A is the bit number of a carrier indication field in the RA-RNTI-scrambled PDCCH.

Step 806: and the UE detects the PDCCH scrambled by the RA-RNTI in a special search space of the UE corresponding to the cell which sends the special preamble sequence and used for transmitting the scheduling signaling of the cell. And determining a cell corresponding to the random access response carried in the PDCCH scrambled by the RA-RNTI according to information contained in a carrier indication domain carried in the PDCCH scrambled by the RA-RNTI.

The above description is directed to the implementation of random access, which is mainly implemented by UE and base station, and the internal structures and functions of these two devices are introduced below.

Referring to fig. 9, the UE in this embodiment includes: a receiving module 901, a control module 902 and a sending module 903.

The receiving module 901 is configured to receive random access configuration information sent by a base station. Specifically, the receiving module 901 receives random access configuration information sent by a base station through a PDCCH order (order) or Radio Resource Control (RRC) signaling, where the random access configuration information at least includes index information of an exclusive preamble sequence of a cell that needs to be randomly accessed and index information of an exclusive PRACH resource, and the cell is configured to the UE.

The control module 902 is configured to determine, according to the configuration information, an exclusive random access preamble sequence used in a cell that needs to perform random access and an exclusive physical random access channel PRACH resource used for transmitting the exclusive preamble sequence.

The sending module 903 is configured to send the dedicated preamble sequence to the base station through the determined dedicated PRACH resource on the cell that needs to perform random access.

The receiving module 901 is further configured to detect a physical downlink control channel PDCCH scrambled by using a random access radio network temporary identifier RA-RNTI in a dedicated search space of the UE, and obtain a random access response of the cell that sends the dedicated preamble sequence from the PDCCH, where the random access response at least includes a timing advance TA for uplink synchronization adjustment of the cell that sends the dedicated preamble sequence.

Preferably, the random access response further includes an uplink scheduling grant (UL grant) signaling corresponding to the cell that sent the dedicated preamble sequence.

The receiving module 901 is specifically configured to detect the PDCCH scrambled by the RA-RNTI in a dedicated search space of the UE on the cell, corresponding to the cell that sends the dedicated preamble sequence, and configured to transmit the scheduling signaling of the cell.

When the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the receiving module 901 is configured to detect the PDCCH scrambled by the RA-RNTI in the dedicated search space of the UE in the cell that sends the dedicated preamble sequence, where a random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to a cell in which the PDCCH scrambled by the RA-RNTI is transmitted.

When the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the receiving module 901 is configured to detect the PDCCH scrambled by the RA-RNTI in a dedicated search space of the UE in a cell performing cross-carrier scheduling on the cell that sends the dedicated preamble sequence, where a random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to a cell indicated by a carrier indicator field carried in the PDCCH scrambled by the RA-RNTI.

Preferably, the PDCCH scrambled by the RA-RNTI adopts a DCI format supported by a transmission mode of the cell that sends the dedicated preamble sequence, where the DCI format includes a DCI format for carrying an uplink scheduling grant UL grant and a DCI format for carrying a downlink scheduling grant DL grant.

And when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K, and the K is the bit number of the TA command corresponding to the cell which sends the exclusive preamble sequence. When the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K + A, the K is the bit number corresponding to the TA command of the cell which sends the exclusive preamble sequence, and the A is the bit number of a carrier indication domain in the PDCCH scrambled by the RA-RNTI.

Or, when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the DCI format is a DCI format with a carrying bit number not less than K + L, where K is the bit number of the TA command corresponding to the cell that has sent the dedicated preamble sequence, and L is the bit number of the UL grant corresponding to the cell that has sent the dedicated preamble sequence. When the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K + L + A, the K is the bit number of the TA command corresponding to the cell which sends the exclusive preamble sequence, the L is the bit number of the UL grant corresponding to the cell which sends the exclusive preamble sequence, and the A is the bit number of a carrier indication domain in the PDCCH scrambled by the RA-RNTI.

Preferably, K is 11, L is 20, and a is 3.

The cell which needs to perform random access and/or the cell which sends the exclusive preamble sequence are/is the secondary cell of the UE.

Referring to fig. 10, the base station in this embodiment includes: a transmitting module 1001, a receiving module 1002 and a control module 1003.

The sending module 1001 is configured to send random access configuration information to a user equipment UE, and configure a dedicated random access preamble (preamble) sequence and a dedicated Physical Random Access Channel (PRACH) resource for a cell of the UE that needs to perform random access. Specifically, the sending module 1001 sends random access configuration information to the UE through a PDCCH order (order) or Radio Resource Control (RRC) signaling, where the random access configuration information at least includes index information of an exclusive preamble sequence of a cell that needs to be randomly accessed and index information of an exclusive PRACH resource, and the cell is configured to the UE.

The receiving module 1002 is configured to receive an exclusive preamble sequence sent by the UE on an exclusive PRACH resource configured to the UE.

The control module 1003 is configured to determine, according to the received dedicated preamble sequence, a Timing Advance (TA) value corresponding to a cell receiving the dedicated preamble sequence.

The sending module 1001 is further configured to send a random access response to the UE through a Physical Downlink Control Channel (PDCCH) scrambled by a random access radio network temporary identifier (RA-RNTI) in a dedicated search space of the UE, where the random access response at least includes a TA used for uplink synchronization adjustment of the cell receiving the dedicated preamble sequence.

Preferably, the random access response further includes an uplink scheduling grant (UL grant) signaling corresponding to the cell receiving the dedicated preamble sequence.

The sending module 1001 is specifically configured to send a random access response to the UE through the PDCCH scrambled by the RA-RNTI in a dedicated search space of the UE on the cell corresponding to the cell receiving the dedicated preamble sequence and configured to transmit the scheduling signaling of the cell.

When the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the sending module 1001 is configured to send a random access response to the UE through the PDCCH scrambled by the RA-RNTI in a dedicated search space of the UE on a cell receiving a dedicated preamble sequence, where the random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to a cell where the PDCCH scrambled by the RA-RNTI is transmitted.

When the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the sending module is used for sending a random access response to the UE through the PDCCH scrambled by the RA-RNTI in a special search space of the UE on a cell performing cross-carrier scheduling on the cell receiving the special preamble sequence, wherein the random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to a cell indicated by a carrier indication domain carried in the PDCCH scrambled by the RA-RNTI.

Preferably, the PDCCH scrambled by the RA-RNTI adopts a DCI format supported by a transmission mode of the cell receiving the dedicated preamble sequence, where the DCI format includes a DCI format for carrying an uplink scheduling grant UL grant and a DCI format for carrying a downlink scheduling grant DL grant.

And when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K, and the K is the bit number of the TA command corresponding to the cell receiving the exclusive preamble sequence. When the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K + L, the K is the bit number of the TA command corresponding to the cell receiving the exclusive preamble sequence, and the L is the bit number of the UL grant corresponding to the cell receiving the exclusive preamble sequence.

Or, when the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K + A, wherein K is the bit number of the TA command corresponding to the cell receiving the exclusive preamble sequence, and A is the bit number of a carrier indication domain in the PDCCH scrambled by the RA-RNTI. When the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K + L + A, the K is the bit number of a TA command corresponding to the cell receiving the exclusive preamble sequence, the L is the bit number of a UL grant corresponding to the cell receiving the exclusive preamble sequence, and the A is the bit number of a carrier indication domain in the PDCCH scrambled by the RA-RNTI.

Preferably, K is 11, L is 20, and a is 3.

The cell which needs to perform random access and/or the cell which receives the exclusive preamble sequence are/is the secondary cell of the UE.

In the embodiment of the invention, the random access response is transmitted by using the Physical Downlink Control Channel (PDCCH) scrambled by the random access radio network temporary identifier (RA-RNTI) in the special search space of the UE, the random access process is realized, the random access method is particularly suitable for the SCell, the PDCCH scrambled by the RA-RNTI is transmitted in the special search space of the UE, the blind detection times of the UE on the PDCCH are not increased, the random access response is not required to be transmitted on the PDSCH, the PDSCH transmission scheduled by the PDCCH scrambled by the RA-RNTI on the SCell is avoided, and compared with the transmission of the random access response on the PDSCH scheduled by the PDCCH scrambled by the RA-RNTI, the overhead of downlink data transmission is saved to a certain extent. The embodiment of the invention also provides a solution for cross-carrier scheduling and non-cross-carrier scheduling.

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

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

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

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

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

Claims

1. A method of random access, comprising the steps of:

2. The method of claim 1, wherein the UE receiving the random access configuration information sent by the base station comprises: and the UE receives random access configuration information sent by the base station through a PDCCH order or a Radio Resource Control (RRC) signaling, wherein the random access configuration information at least comprises index information of an exclusive preamble sequence of a cell needing random access and configured to the UE and index information of an exclusive PRACH resource.

3. The method of claim 1, wherein the random access response further includes uplink scheduling grant (UL grant) signaling corresponding to the cell that transmitted the dedicated preamble sequence.

4. The method of claim 1 or 3, wherein the UE detecting the PDCCH scrambled with the RA-RNTI in a dedicated search space of the UE comprises:

5. The method according to claim 4, wherein the detecting, by the UE, the PDCCH scrambled by the RA-RNTI in the dedicated search space of the UE on the cell corresponding to the cell that sent the dedicated preamble sequence and used for transmitting the scheduling signaling of the cell includes: when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the UE detects the PDCCH scrambled by the RA-RNTI in a special search space of the UE on the cell which sends the special preamble sequence, and the random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to the cell where the PDCCH scrambled by the RA-RNTI is transmitted;

when the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the UE detects the PDCCH scrambled by the RA-RNTI in a special search space of the UE on a cell which carries out cross-carrier scheduling on the cell which sends the special preamble sequence, and the random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to a cell indicated by a carrier indication domain carried in the PDCCH scrambled by the RA-RNTI.

6. The method of claim 3, 4 or 5, wherein the PDCCH scrambled by the RA-RNTI adopts a DCI format supported by a transmission mode of the cell which transmits the dedicated preamble sequence, and the DCI format comprises a DCIformat for carrying an uplink scheduling grant (UL grant) and a DCI format for carrying a downlink scheduling grant (DL grant).

7. The method of claim 6, wherein when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the DCI format is a DCI format with a carrying bit number not less than K, and the K is a bit number of the TA command corresponding to the cell which sends the dedicated preamble sequence; or,

when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K + L, the K is the bit number of the TA command corresponding to the cell which sends the exclusive preamble sequence, and the L is the bit number of the UL grant corresponding to the cell which sends the exclusive preamble sequence; or,

when the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K + A, the K is the bit number of the TA command corresponding to the cell which sends the exclusive preamble sequence, and the A is the bit number of a carrier indication domain in the PDCCH scrambled by the RA-RNTI; or,

when the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K + L + A, the K is the bit number of the TA command corresponding to the cell which sends the exclusive preamble sequence, the L is the bit number of the UL grant corresponding to the cell which sends the exclusive preamble sequence, and the A is the bit number of a carrier indication domain in the PDCCH scrambled by the RA-RNTI.

8. The method of claim 7, wherein K-11.

9. The method of claim 7, wherein L-20.

10. The method according to any of claims 1 to 9, wherein the cell requiring random access and/or the cell transmitting a dedicated preamble sequence is a secondary cell of the UE.

11. A method of random access, comprising the steps of:

12. The method of claim 11, wherein the step of the base station sending random access configuration information to the User Equipment (UE) comprises: the base station sends random access configuration information to the UE through a PDCCH order or a Radio Resource Control (RRC) signaling, wherein the random access configuration information at least comprises index information of an exclusive preamble sequence of a cell needing random access and configured to the UE and index information of an exclusive PRACH resource.

13. The method of claim 11, wherein the random access response further comprises uplink scheduling grant (UL grant) signaling corresponding to the cell receiving the dedicated preamble sequence.

14. The method according to claim 11 or 13, wherein the step of the base station sending a random access response to the UE through a physical downlink control channel PDCCH scrambled by a random access radio network temporary identity, RA-RNTI, in the dedicated search space of the UE comprises:

and the base station sends a random access response to the UE through the PDCCH scrambled by the RA-RNTI in a special search space of the UE on the cell which corresponds to the cell receiving the special preamble sequence and is used for transmitting the scheduling signaling of the cell.

15. The method according to claim 14, wherein the base station sends a random access response to the UE through the PDCCH scrambled by the RA-RNTI in a dedicated search space of the UE on a cell corresponding to the cell receiving the dedicated preamble sequence and used for transmitting the scheduling signaling of the cell, specifically comprising:

when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the base station sends a random access response to the UE through the PDCCH scrambled by the RA-RNTI in a special search space of the UE on the cell receiving the special preamble sequence, wherein the random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to the cell where the PDCCH scrambled by the RA-RNTI is transmitted;

when the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the base station sends a random access response to the UE through the PDCCH scrambled by the RA-RNTI in a special search space of the UE on a cell which carries out cross-carrier scheduling on the cell receiving the special preamble sequence, wherein the random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to a cell indicated by a carrier indication domain carried in the PDCCH scrambled by the RA-RNTI.

16. The method of claim 13, 14 or 15, wherein the PDCCH scrambled by the RA-RNTI adopts a DCI format supported by a transmission mode of the cell receiving the dedicated preamble sequence, and wherein the DCI format comprises a DCI format for carrying an uplink scheduling grant, UL grant, and a DCI format for carrying a downlink scheduling grant, DL grant.

17. The method of claim 16, wherein when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the DCI format is a DCI format carrying a number of bits not less than K, where K is a number of bits of a TA command corresponding to the cell receiving the dedicated preamble sequence; or,

when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K + L, the K is the bit number of a TA command corresponding to the cell receiving the exclusive preamble sequence, and the L is the bit number of a UL grant corresponding to the cell receiving the exclusive preamble sequence; or,

when the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K + A, the K is the bit number of the TA command corresponding to the cell receiving the exclusive preamble sequence, and the A is the bit number of a carrier indication domain in the PDCCH scrambled by the RA-RNTI; or,

when the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the DCI format is a DCI format with the carrying bit number not less than K + L + A, the K is the bit number of a TA command corresponding to the cell receiving the exclusive preamble sequence, the L is the bit number of a UL grant corresponding to the cell receiving the exclusive preamble sequence, and the A is the bit number of a carrier indication domain in the PDCCH scrambled by the RA-RNTI.

18. The method of claim 17, wherein K-11.

19. The method of claim 17, wherein L-20.

20. The method according to any of claims 11 to 19, wherein the cell requiring random access and/or the cell receiving a dedicated preamble sequence is a secondary cell of the UE.

21. A User Equipment (UE), comprising:

22. The UE of claim 21, wherein the receiving module is configured to receive random access configuration information sent by the base station through a PDCCH order or radio resource control RRC signaling, where the random access configuration information at least includes index information of an dedicated preamble sequence and index information of an dedicated PRACH resource of a cell that needs to be randomly accessed and is configured to the UE.

23. The UE of claim 21, wherein the random access response further includes UL grant signaling corresponding to the cell that transmitted the dedicated preamble sequence.

24. The UE of claim 21 or 23, wherein the receiving module is configured to detect the PDCCH scrambled by the RA-RNTI in a dedicated search space of the UE on a cell corresponding to the cell that sent the dedicated preamble sequence and used for transmitting scheduling signaling of the cell.

25. The UE of claim 24, wherein the receiving module is configured to detect the RA-RNTI-scrambled PDCCH in a dedicated search space of the UE on the cell that transmitted the dedicated preamble sequence when the RA-RNTI-scrambled PDCCH does not employ cross-carrier scheduling, and wherein a random access response carried in the RA-RNTI-scrambled PDCCH corresponds to a cell in which the RA-RNTI-scrambled PDCCH is transmitted;

when the PDCCH scrambled by the RA-RNTI adopts cross-carrier scheduling, the receiving module is used for detecting the PDCCH scrambled by the RA-RNTI in a special search space of the UE on a cell which carries out cross-carrier scheduling on the cell which sends the special preamble sequence, and the random access response carried in the PDCCH scrambled by the RA-RNTI corresponds to a cell indicated by a carrier indication domain carried in the PDCCH scrambled by the RA-RNTI.

26. The ue of claim 23, 24 or 25, wherein the PDCCH scrambled by the RA-RNTI employs a DCI format supported by a transmission mode of the cell transmitting the dedicated preamble sequence, and wherein the DCI format includes a DCI format for carrying an uplink scheduling grant UL grant and a DCI format for carrying a downlink scheduling grant DL grant.

27. The UE of claim 26, wherein when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the DCI format is a DCI format with a carrying bit number not less than K, and the K is a bit number of the TA command corresponding to the cell that sent the dedicated preamble sequence; or,

28. The user equipment of claim 27, wherein K-11.

29. The user equipment of claim 27, wherein the L-20.

30. The UE according to any of claims 21 to 29, wherein the cell requiring random access and/or the cell sending a dedicated preamble sequence is a secondary cell of the UE.

31. A base station, comprising:

32. The base station of claim 31, wherein the sending module is configured to send random access configuration information to the UE through a PDCCH order or radio resource control RRC signaling, where the random access configuration information at least includes index information of an dedicated preamble sequence and index information of an dedicated PRACH resource of a cell that needs to be randomly accessed and is configured to the UE.

33. The base station of claim 31, wherein the random access response further comprises uplink scheduling grant (UL grant) signaling corresponding to the cell receiving the dedicated preamble sequence.

34. The base station according to claim 31 or 33, wherein the sending module is configured to send a random access response to the UE through the PDCCH scrambled by the RA-RNTI in a dedicated search space of the UE on a cell corresponding to the cell receiving the dedicated preamble sequence and used for transmitting the scheduling signaling of the cell.

35. The base station of claim 34, wherein when the RA-RNTI scrambled PDCCH does not employ cross-carrier scheduling, the sending module is configured to send a random access response to the UE through the RA-RNTI scrambled PDCCH in the dedicated search space of the UE on the cell that receives the dedicated preamble sequence, where the random access response carried in the RA-RNTI scrambled PDCCH corresponds to a cell in which the RA-RNTI scrambled PDCCH is transmitted;

36. The base station of claim 33, 34 or 35, wherein the PDCCH scrambled by the RA-RNTI employs a DCI format supported by a transmission mode of the cell receiving the dedicated preamble sequence, and wherein the DCI format includes a DCI format for carrying an uplink scheduling grant, UL grant, and a DCI format for carrying a downlink scheduling grant, DL grant.

37. The base station of claim 36, wherein when the PDCCH scrambled by the RA-RNTI does not adopt cross-carrier scheduling, the DCI format is a DCI format carrying a number of bits not less than K, where K is a number of bits of a TA command corresponding to the cell receiving the dedicated preamble sequence; or,

38. The base station of claim 37, wherein K-11.

39. The base station of claim 37, wherein the L-20.

40. The base station according to any of claims 31 to 39, wherein the cell requiring random access and/or the cell receiving dedicated preamble sequence is a secondary cell of the UE.