WO2011035700A1

WO2011035700A1 - Method and system for implementing random access

Info

Publication number: WO2011035700A1
Application number: PCT/CN2010/077043
Authority: WO
Inventors: 杜忠达; 喻斌; 沈晓芹; 张银成
Original assignee: 中兴通讯股份有限公司
Priority date: 2009-09-28
Filing date: 2010-09-17
Publication date: 2011-03-31
Also published as: CN102036407A

Abstract

A method and system for implementing random access are provided. In the method of the present invention, UEs can select their respective resident downlink component carriers according to the information of other downlink component carriers which have different Physical Random Access Channel (PRACH) resources from the initial resident downlink component carrier, wherein the information is carried in the system message sent from the network side, and perform the random access through the uplink component carriers corresponding to the selected resident downlink component carriers, thus part of the UEs residing on the initial resident downlink component carrier are distributed to other selected downlink component carriers, which thereby ensures load balance for the access, assigns the carrier resources reasonably and reduces the probability of congestion when UEs perform random access on one uplink component carrier.

Description

Method and system for realizing random access

The present invention relates to an LTE-Advanced (Long-Term Evolution advance, LTE-A) system, and more particularly to a method and system for implementing random access. Background technique

FIG. 1 is a schematic diagram of the composition of a cellular wireless communication system. As shown in FIG. 1, it is mainly composed of a terminal, a base station, and a core network. The network composed of the base stations is called a radio access network (RAN), and is used for management of access layer transactions such as radio resources. There may be physical or logical connections between the base stations according to actual conditions, such as between the base station 1 and the base station 2 in FIG. 1, or between the base station 1 and the base station 3. Each base station can be connected to one or more core network nodes (CN, Core Network). The core network is used to be responsible for non-access layer transactions such as location updates, etc., and is the anchor point of the user plane. A terminal (UE, User Equipment) refers to various devices that can communicate with a cellular wireless communication network, such as a mobile phone or a notebook computer.

To meet the growing demand for high-bandwidth, high-speed mobile access, the 3rd Generation Partnership Projects (3GPP, Third Generation Partnership Projects) introduced the LTE-A standard. The LTE-A system aggregates several carriers to support higher bandwidths, resulting in higher data rates. Each aggregated carrier is called a component carrier (CC), and the component carriers may be continuous or discontinuous.

The downlink component carrier (DL CC ) in the LTE-A system may include a synchronization channel and a physical broadcast channel (PBCH), where the synchronization channel includes a primary synchronization channel and a secondary synchronization channel. A broadcast channel on a downlink component carrier refers to a channel carrying a broadcast message of a certain carrier or a certain carrier or an entire cell, and these messages may be used by all terminals in the cell or all terminals having the same attribute in the cell. receive. In addition, the broadcast channel can refer to The physical channel of the physical layer may also refer to a transport channel of a medium access control (MAC) sublayer or a logical channel of a radio resource management (RRC) sublayer. The information carried by the broadcast channel can also be referred to as System Information. The broadcast channel broadcasts information, and may include (1) a frequency of an uplink carrier and a bandwidth of the uplink carrier; (2) a configuration parameter of the physical random access channel corresponding to the uplink carrier. The primary synchronization signal (PSS, Primary Synchronization Symbol) and the secondary synchronization signal (SSS, Secondary Synchronization Symbol) are information carried on the primary and secondary synchronization channels, respectively. PSS, SSS, PBCH and System Information Block (SIB) are required on each DL CC.

The random access process of the terminal of the Rel8 version of the LTE system is roughly as follows:

The UE performs cell search with a frequency grating of 100 kHz; the UE detects PSS/SSS/PBCH on a certain DL CC and receives the SIB; normally, the DL CC is the DL CC with the strongest signal.

The UE allocates a preamble (Preamble) code to the base station according to the physical random access channel (PRACH) configuration resource carried in the received DL CC; the UE receives a random access channel (RACH) response message of the DL CC, where the DL CC and the DL CC The Preamble's UL CC is matched.

If the random access procedure of the Rel8 version is still used in the carrier aggregation scenario of LTE-A, when a certain DL CC signal is strongest, many UEs select the DL CC as the resident carrier in the cell search. Case. In this case, since the SIB only includes the PRACH configuration information of the UL CC corresponding to the DL CC, most UEs can only access the UL CC, and thus the PRACH resource congestion of a certain UL CC occurs. On other UL CCs, there are only a few users with unbalanced load access. Summary of the invention

In view of this, the main object of the present invention is to provide a method and system for implementing random access, which can ensure load balancing of access and reasonably allocate carrier resources.

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

A method for implementing random access, comprising: a system signal that initially camps on a downlink component carrier In the SIB, the information of the other downlink component carriers having different PRACH resources from the initial camping downlink component carrier is set, and is sent to the user terminal UE that is selected to access the initial camping downlink carrier. The UE is configured according to the received SIB. The information of the downlink component carrier that is carried is selected, and the downlink component carrier that is camped on is selected, and the uplink component carrier corresponding to the selected downlink component carrier is randomly accessed.

The information about the other downlink component carriers that are set in the SIB is: the cell identification number corresponding to the downlink component carrier having the different PRACH resources of the initial resident row component carrier; and

a center frequency of other downlink component carriers having different PRACH configuration information in the same continuous frequency band as the initial camped downlink component carrier; and/or,

The bandwidth of other downlink component carriers having different PRACH configuration information in the same continuous frequency band as the initial camped downlink component carrier.

The method of issuing the SIB is broadcast.

The UE selects the downlink component carrier that each camps to be:

The UE randomly selects one downlink component carrier to camp in the downlink component carrier broadcasted in the SIB of the initial camping downlink component carrier; or

The UE selects one downlink component carrier to camp according to a preset random selection policy. The random selection strategy is:

The downlink component carrier numbered n is selected according to the formula IMSI MOD N = n; where N is the number of downlink component carriers; n is the number of N downlink component carriers, and the value is 0 ~ (N-1); IMSI is the IMSI number of the UE; MOD is the modulo operator.

The method for obtaining the number n of the N downlink component carriers is as follows: The center frequency of the downlink component carrier is numbered 0 to N-1 from low to high.

The UE performs random access by using the uplink component carrier corresponding to the selected downlink component carrier: For selecting a UE that camps on the initial camping downlink component carrier, the corresponding uplink component carrier and PRACH resource configuration information are obtained from the SIB on the downlink carrier; and the corresponding uplink component carrier is configured according to the PRACH configuration information. Random access procedure;

For the UE that selects another downlink component carrier to camp, the SIB of the downlink component carrier is read, and the uplink component carrier corresponding to the downlink component carrier and its PRACH configuration information are acquired; and the corresponding uplink component carrier is randomly configured according to the PRACH configuration information. Access process.

A system for implementing random access includes at least a network side and a UE, where

The network side is configured to: set, in an SIB that initially camps on a downlink component carrier, information about a downlink component carrier that has a different PRACH resource from the initial camping downlink component carrier, and send the information to the UE that selects to access the initial camped downlink carrier. ;

The UE is configured to select a downlink component carrier that is camped on by the downlink component carrier that is carried in the received SIB, and perform random access by using the uplink component carrier corresponding to the selected downlink component carrier.

The network side delivers the SIB by broadcast.

It can be seen from the foregoing technical solution provided by the present invention that, in the method of the present invention, the UE may select, by using, information about other downlink component carriers that have different PRACH resources from the initial camping downlink component carrier carried in the system message delivered by the network side. Each of the downlink component carriers that resides, and performs random access by selecting the uplink component carrier corresponding to the resident downlink component carrier, and succeeds The partial UEs that are camped on the initial camping carrier are offloaded to other selected downlink component carriers, ensuring load balancing of the access, reasonably allocating carrier resources, and reducing congestion of random access of the UE on one uplink component carrier. The chance. DRAWINGS

1 is a schematic diagram of the composition of a cellular wireless communication system;

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

3 is a schematic diagram of a system for implementing random access according to the present invention;

4 is a schematic diagram showing a correspondence relationship between a DL CC and a UL CC in the first embodiment of the present invention; and FIG. 5 is a schematic diagram showing a correspondence between a DL CC and a UL CC in the second, third, fourth and fifth embodiments of the present invention. detailed description

2 is a flowchart of a method for implementing random access according to the present invention. As shown in FIG. 2, the method includes the following steps: Step 200: Set a downlink with different PRACH resources from an initial camping downlink component carrier in an SIB that initially camps on a downlink component carrier. The information of the component carrier is sent to the UE that selects to access the initial camped downlink carrier. Here, the downlink component carrier having a different PRACH resource from the initial camping downlink component carrier is: a downlink component carrier other than the initially camped downlink carrier carried in the system message delivered by the network side.

The information about the downlink component carrier that has a different PRACH resource from the initial camping downlink component carrier that is set in the SIB may include: a cell identifier number (Cell-ID) corresponding to the DL CCs, and,

The center frequency (dl-CarrierFreq) of other DL CCs having different PRACH configuration information in the same continuous frequency band as the initial camping DL CC; and/or,

The bandwidth ( dl-Bandwidth ) of other DL CCs having different PRACH configuration information in the same continuous frequency band as the initial resident DL CC. In this step, the information of the downlink component carrier in the system including the initial camping downlink component carrier is carried in the SIB of the initial camping downlink component carrier.

In this step, the SIB can be broadcasted.

Step 201: The UE selects each of the self-resident downlink component carriers according to the information of the downlink component carrier carried in the received SIB.

It is assumed that N downlink component carriers are numbered from 0 to (N-1) according to their center frequency from low to high, including the initial camping downlink component carrier, and N is the number of downlink component carriers. In this step, the UE selects the downlink component carrier that each camps to be:

The UE randomly selects one downlink component carrier to camp on the plurality of downlink component carriers broadcasted in the SIB of the initial camping downlink component carrier; or

The UE selects a downlink component carrier to camp according to the preset random selection policy, where the preset random selection policy may be: the UE selects the downlink component carrier numbered n according to the formula IMSI MOD N = n, and n is N downlinks. The number of the component carrier, which is 0 ~ ( N-1 ), where IMSI is the IMSI number of the UE, and MOD is the modulo operator.

Step 202: The UE performs random access by using the uplink component carrier corresponding to the selected downlink component carrier.

For the UE still selecting to camp on the initial camping downlink component carrier, the UE acquires its corresponding uplink component carrier and PRACH resource configuration information from the SIB on the downlink carrier; and performs PRACH configuration information on the corresponding uplink component carrier. Perform a random access process.

For a UE that selects another downlink component carrier (non-initial resident carrier) to camp, the UE reads the SIB of the downlink component carrier, acquires the UL CC corresponding to the DL CC, and the PRACH configuration information thereof; The PRACH configuration information is used for the random access process.

In the method of the present invention, the UE may select the downlink component carrier that resides in each other through the information of the other downlink component carriers in the system that has different PRACH resources from the initial camping downlink component carrier, and select the resident by using the downlink component carrier. Uplink component carrier corresponding to the downlink component carrier Performing random access, successfully splitting some UEs residing in the initial camping carrier to other selected downlink component carriers, ensuring load balancing of access, reasonably allocating carrier resources, and reducing UE in one UL CC The probability of congestion on random access.

For the method of the present invention, a system for implementing random access is also provided. FIG. 3 is a schematic diagram of a system for implementing random access according to the present invention, which includes at least a network side and a UE, where

a network side, configured to set, in an SIB that initially camps on a downlink component carrier, information about a downlink component carrier that has a different PRACH resource from an initial camping downlink component carrier, and send the information to a UE that selects to access the initial camping downlink carrier; Here, the downlink component carrier having a different PRACH resource from the initial camping downlink component carrier is: a downlink component carrier other than the initial camping downlink carrier carried in the system message delivered by the network side.

The network side delivers the SIB by broadcast.

The method of the present invention will be described in detail below with reference to the embodiments.

4 is a schematic diagram of a correspondence relationship between a DL CC and a UL CC according to the first embodiment of the present invention. As shown in FIG. 4, the dotted line indicates the downlink, the dotted line below indicates the uplink, and the large blank square indicates the component carrier; The shaded hatching indicates SCH/BCH, the right shaded hatching indicates PRACH, and the small squared shading indicates PUCCH. In the first embodiment, there are three DL CCs in the system, namely DL CC#0, DL CC#1 and DL CC#2, and there are also three UL CCs, which are UL CC#0, UL CC#1 and UL CC#2, each UL CC corresponds to one DL CC. It is assumed that there are three terminal UE#0, UE#1 and UE#2 whose IMSI numbers are IMSI#0, IMSI#1 and IMSI#2 are to be randomly accessed, and it is assumed that the DL CC#0 signal is the strongest at this time. The three UEs will select it as the initial camping downlink component carrier.

Since UL CC#0, UL CC#1 and UL CC#2 correspond to different DL CCs, The PRACH resources are also different, so the center frequency, bandwidth, and Cell-ID information of the other two DL CCs, that is, DL CC#1 and DL CC#2, are added to the SIB of the initial camping DL CC#0 carrier, and Broadcast to all UEs, UE#0, UE#1 and UE#2, through a broadcast channel.

It is assumed that DL CC#0, DL CC#1 and DL CC#2 are renumbered according to the center frequency from high to low, respectively corresponding to 0, 1, and 2, and IMSI#0 MOD 3=0, IMSI#1 MOD 3=1 , IMSI#2 MOD 3=2, then UE#0, UE#1 and UE#2 respectively select the downlink component carrier numbered 0, 1, and 2, that is, UE#0 still resides in the initial resident DL. On the CC#0 carrier, UE#1 and UE#2 respectively reside on the DL CC#1, DL CC#2 carrier.

For UE#0 still residing on the initial camped UL CC#0, the corresponding UL CC#0 and PRACH configuration information may be obtained from the system information on the downlink component carrier;

For UE#1 and UE#2, which respectively select DL CC#1 and DL CC#2 (non-initial resident carrier) to camp, the system information of DL CC#1 and DL CC#2 can be read separately, respectively. Corresponding UL CC#1 and PRACH configuration information, UL CC#2 and PRACH configuration information.

UE#0, UE#1 and UE#2 perform a random access procedure according to the PRACH configuration information on the corresponding uplink component carrier according to the obtained uplink component carrier and PRACH configuration information. In this way, the three UEs that initially reside in the UL CC#0 are successfully separated by two, which ensures the load balancing of the access, allocates the carrier resources reasonably, and reduces the probability that the UE will be congested by random access on a UL CC.

5 is a schematic diagram of correspondence between DL CC and UL CC in the second, third, fourth, and fifth embodiments of the present invention. As shown in FIG. 5, the dotted line indicates the downlink, and the dotted line indicates the uplink, the large blank. The grid represents the component carrier; the left diagonal shading indicates SCH/BCH, the right diagonal shading indicates PRACH, and the small square shading indicates PUCCH. There are three DL CCs in the system, namely DL CC#0, DL CC#1 and DL CC#2, and there are two UL CCs, namely UL CC#0 and UL CC#1.

In the second embodiment, it is assumed that UL CC#0 corresponds only to DL CC#0, and UL CC#1 pairs Should be DL CC#1 and DL CC#2. Although DL CC#1 and DL CC#2 correspond to the same UL CC, each is configured with a different Preamble.

It is assumed that there are three terminals UE#0, IMSI#1 and IMSI#2 whose IMSI numbers are IMSI#0, UE#1 and UE#2 are to be randomly accessed, and it is assumed that the DL CC#1 signal is the strongest at this time. The three UEs will select it as the initial camping downlink component carrier. Since DL CC#1 and DL CC#0 correspond to different DL CCs, their PRACH resources are also different. At the same time, DL CC#1 and DL CC#2 correspond to different Preambles, and their PRACH resources are also different. Therefore, the center frequency, the bandwidth, and the Cell-ID information of the other two DL CCs are added to the SIB that initially camps on the DL CC#1 carrier, and are broadcasted to all UEs, that is, UE#0, UE#1, and UE through the broadcast channel. #2.

It is assumed that DL CC#0, DL CC#1 and DL CC#2 are renumbered according to the center frequency from high to low, respectively corresponding to 0, 1, and 2, and IMSI#0 MOD 3=0, IMSI#1 MOD 3=1 , IMSI#2 MOD 3=2, then UE#0, UE#1, UE#2 respectively select the downlink component carrier numbered 0, 1, and 2, that is, UE#1 still resides in the initial resident DL. On the CC#1 carrier, UE#0 and UE#2 reside on the DL CC#0 and DL CC#2 carriers, respectively.

For UE#1 still camping on the initial camping DL CC#1, its corresponding uplink component carrier UL CC#1 and PRACH configuration information may be obtained from system information on the downlink component carrier; for selecting DL CC respectively #0 and DL CC#2 (non-initial resident carrier) UE#0 and UE#2, which are camped on, can read the system information of DL CC#0 and DL CC#2, respectively, and obtain the corresponding UL CCs respectively. #0 and PRACH configuration information, UL CC#2 and PRACH configuration information.

In the third embodiment, it is assumed that UL CC#0 corresponds only to DL CC#0, and UL CC#1 pair Should be DL CC#1 and DL CC#2. Although DL CC#1 and DL CC#2 correspond to the same UL CC, each corresponds to a different physical resource block (PRB).

It is assumed that there are three terminals UE#0, IMSI#1 and IMSI#2 whose IMSI numbers are IMSI#0, UE#1 and UE#2 are to be randomly accessed, and it is assumed that the DL CC#1 signal is the strongest at this time. The three UEs will select it as the initial camping downlink component carrier. Since DL CC#1 and DL CC#0 correspond to different DL CCs, their PRACH resources are also different. At the same time, DL CC#1 and DL CC#2 correspond to different PRBs, and their PRACH resources are also different. Therefore, the center frequency, the bandwidth, and the Cell-ID information of the other two DL CCs are added to the SIB that initially camps on the DL CC#1 carrier, and are broadcasted to all UEs, that is, UE#0, UE#1, and UE through the broadcast channel. #2.

In the fourth embodiment, it is assumed that UL CC#0 corresponds only to DL CC#0, and UL CC#1 pair It should be DL CC#1 and DL CC#2, and DL CC#1 and DL CC#2 have the same PRACH. It is assumed that there are three terminals UE#0, IMSI#1 and IMSI#2 whose IMSI numbers are IMSI#0, UE#1 and UE#2 are to be randomly accessed, and it is assumed that the DL CC#1 signal is the strongest at this time. The three UEs will select it as the initial camping downlink component carrier. Since DL CC#1 and DL CC#0 correspond to different UL CCs, the PRACH resources are different; and DL CC#1 and UL CC#2 correspond to the same PRACH resource, so it only needs to be added in the SIB of the DL CC#1 carrier. The center frequency, bandwidth, and Cell-ID information of DL CC #0 are set and broadcast to all UEs, UE#0, UE#1 and UE#2, through a broadcast channel.

Assume that DL CC#0, DL CC#1 are renumbered according to the center frequency from high to low and correspond to 0, 1 respectively, and IMSI#0 MOD 2=0, IMSI#1 MOD 2=1, IMSI#2 MOD 2= 1 , UE#0, UE#1 and UE#2 respectively select the downlink component carrier numbered 0, 1, and 1, respectively, that is, UE#1 and UE#2 still reside in the initial resident DL CC#1. On the carrier, UE#0 resides on the DL CC#0 carrier.

For UE#1 and UE#2 still residing on the initial camped UL CC#1, the corresponding uplink component carrier UL CC#1 and PRACH configuration information may be obtained from system information on the downlink component carrier;

For UE#0 that selects DL CC#0 (non-initial resident carrier) to camp, the system information of DL CC#0 can be read, and the corresponding UL CC#0 and PRACH configuration information is obtained.

UE#0, UE#1 and UE#2 perform a random access procedure according to the PRACH configuration information on the corresponding uplink component carrier according to the obtained uplink component carrier and PRACH configuration information. In this way, the three UEs that initially reside in the UL CC#0 are successfully separated by one, which ensures the load balancing of the access, allocates the carrier resources reasonably, and reduces the probability of the UE being randomly connected to a UL CC.

In the fifth embodiment, it is assumed that UL CC #0 corresponds only to DL CC #0, and UL CC #1 corresponds to DL CC #1 and DL CC #2, and DL CC #2 serves as a reserved component carrier, not as an access. Carrier. It is assumed that there are three terminals UE#0, IMSI#1 and IMSI#2 whose IMSI numbers are IMSI#0, UE#1 and UE#2 are to be randomly accessed, and it is assumed that the DL CC#1 signal is the strongest at this time. The three UEs will select it as the initial camping downlink component carrier. Since DL CC#1 and DL CC#0 correspond to different UL CCs, the PRACH resources are different, and UL CC#2 is used as the reserved component carrier and is not used as the access carrier. Therefore, only the SIB of the DL CC#1 carrier is included. The center frequency, bandwidth, and Cell-ID information of the DL CC #0 are added and broadcast to all UEs, UE#0, UE#1 and UE#2, through the broadcast channel.

The above description is only for the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included. Within the scope of protection of the present invention.

Claims

Claim

A method for implementing random access, comprising:

In the system information block SIB of the initial camping downlink component carrier, information about other downlink component carriers having different physical random access channel PRACH resources from the initial camping downlink component carrier is set, and is sent to the selected access to the initial camp. a user terminal UE of a downlink carrier;

The UE selects the downlink component carrier that is camped on according to the information of the downlink component carrier carried in the received SIB, and performs random access by using the uplink component carrier corresponding to the selected downlink component carrier.

The method according to claim 1, wherein the information about the other downlink component carriers that are added in the SIB is: the downlink component carrier that has different PRACH resources from the initial camping downlink component carrier. Cell identification number; and,

3. The method according to claim 1, wherein the method of issuing the SIB is broadcast.

The method according to claim 1, wherein the UE selects a downlink component carrier that each camps to be:

The UE selects one downlink component carrier to camp according to a preset random selection policy.

The method according to claim 4, wherein the random selection strategy is: selecting a downlink component carrier numbered n according to the formula IMSI MOD N = n; wherein

N is the number of downlink component carriers; n is the number of N downlink component carriers, and the value is 0 ~ (N-1); IMSI is the IMSI number of the UE; MOD is the modulo operator.

The method according to claim 5, wherein the method for obtaining the number n of the N downlink component carriers is as follows: the center frequency of the downlink component carrier is numbered from 0 to N-1 in descending order.

The method according to claim 1, wherein the UE performs random access by using an uplink component carrier corresponding to the selected downlink component carrier:

For selecting a UE that camps on the initial camping downlink component carrier, the corresponding uplink component carrier and PRACH resource configuration information are obtained from the SIB on the downlink carrier; and the corresponding uplink component carrier is configured according to the PRACH configuration information. Random access procedure;

A system for implementing random access, which is characterized in that it includes at least a network side and a UE, where

The network side is configured to: set, in an SIB that initially camps on a downlink component carrier, information about a downlink component carrier that has a different physical random access channel PRACH resource from the initial camping downlink component carrier, and send the information to the selected initial station. a UE leaving a line carrier;

The system according to claim 8, wherein the information about the other downlink component carriers that are added in the SIB is: the downlink component carrier that has different PRACH resources from the initial camping downlink component carrier. Cell identification number; and,

a center frequency of other downlink component carriers having different PRACH configuration information in the same continuous frequency band as the initial camped downlink component carrier; and/or, The bandwidth of other downlink component carriers having different PRACH configuration information in the same continuous frequency band as the initial camping downlink component carrier.

The system according to claim 8, wherein the network side delivers the SIB by broadcasting.