CN1838574B - Random Access Method for Time Division Duplex Code Division Multiple Access System - Google Patents

Abstract

The invention discloses a random access method of a time division duplex code division multiple access system, which includes: receiving a random access channel transmission request from a media access control layer at a physical layer of a terminal device side, triggering the start of a random access process of the physical layer ; The terminal device uniquely selects a random access channel according to the transmission format indicated by the media access control layer; the terminal device randomly selects an uplink synchronization channel from the uplink synchronization subchannels and uplink synchronization codes available for a given access service level sub-channel and an uplink synchronization code; the terminal device determines the appropriate transmission power, and transmits the uplink synchronization code on the selected uplink synchronization sub-channel; the terminal device receives the network-side access confirmation information on the forward physical access channel, and the uplink synchronization After completion, the physical random access channel is selected to send the information on the random access channel. The invention can effectively solve the problem that the signature used in the random access process and the definition and selection method of the UpPTS time slot resource are inconsistent with the configuration method.

Description

Random Access Method for Time Division Duplex Code Division Multiple Access System

technical field

The invention relates to the third generation mobile communication system, especially the random access method of the Time Division Duplex Code Division Multiple Access (TD-SCDMA) communication system.

Background technique

The random access process is an important process in the wireless communication system and an important link in the wireless access process. In the TD-SCDMA wireless communication system, one of the third-generation mobile communication systems, the random access process includes Important uplink synchronization process.

The TD-SCDMA system adopts synchronous time division duplex technology, which has relatively strict requirements for uplink and downlink synchronization, especially uplink synchronization. In the TD-SCDMA system, an uplink pilot time slot (UpPTS) and an uplink synchronization code (SYNC_UL) are specially defined for uplink synchronization.

In the TD-SCDMA system, the random access process is a physical layer process. In this process, a very important step is to select the uplink synchronization code and its transmission opportunity in the UpPTS time slot. The selection process is not only the need of the uplink synchronization process, but more importantly, the selection process is the essence of the random access process. Channel (PRACH) contention sharing allocation mode.

In the TD-SCDMA system, a cell is configured with 8 uplink synchronization codes, numbered 0-7. In the random access process, the uplink synchronization codes are also described as signatures. In the process of random access, if the terminal equipment (UE) selects the same signature and transmits at the same opportunity, that is, the UpPTS slot of the same subframe, it will cause a collision and cannot get a response from the base station, resulting in random access. The entry process failed.

In the TD-SCDMA system, different access service qualities are realized by defining different access service classes ASC (Access Service Class) and configuring corresponding resources for each ASC. In the TD-SCDMA system, a total of 8 levels of ASCs from 0 to 7 are set, and the resources configured by the system for each ASC include the signature used in the random access process and UpPTS time slot resources (UpPTS time slot resources are in UpPTS time slot resources) time slot for transmission). At the same time, on the UE side, the system defines 16 ACs (Access Class) from 0 to 15, and one or more ACs can be set for each UE. In the system broadcast message, the system broadcasts to the UE the number of configured ASCs, the signature configured for each ASC and the UpPTS time slot resource, and broadcasts the correspondence between ACs and ASCs. According to the corresponding relationship and the AC value set therein, the UE determines the ASC value that the UE will use in the random process, and further determines the signature and UpPTS time slot resources that can be used in the random process.

For the TD-SCDMA system, in the latest 3GPP protocol "3GPP TS 25.224V6.3.0", the UpPCH (uplink synchronization channel) sub-channel is defined as: an UpPCH sub-channel is defined as one (or a group) signature and some UpPTS sub-channels frame. In this definition, an UpPCH sub-channel defines an UpPTS time slot resource through a subframe, and an UpPCH sub-channel defines a signature and an UpPTS time slot resource to be used in a random process at the same time. Therefore, in the subsequent random access process, the signature and UpPTS slot resource selection process is defined as follows:

■ Randomly select an UpPCH sub-channel from the available UpPCH sub-channels for a given ASC.

The random function will make each selectable item equally likely to be selected.

For the TD-SCDMA system, in the broadcast information of the latest protocol "3GPP TS 25.331V6.4.0", the configuration of the signature and UpPTS time slot resources is realized through the ASC setting information unit, and its structure diagram is shown in Figure 1. Corresponding to each ASC value, it includes the available uplink synchronization code (namely signature) and the number of sub-channels and available sub-channels, where the sub-channels are UpPTS time slot resources. In this configuration method, the signature and UpPTS time slot resources are configured as two independent resources.

From the above analysis, it can be seen that among the two protocols that belong to the 3GPP protocol, the definition and use of signature and UpPTS time slot resources in the agreement "3GPP TS 25.224V6. There is an inconsistency between the signature and the method of configuring the UpPTS slot resource. This inconsistency will lead to: on the one hand, when configuring the signature and UpPTS time slot resources through the agreement "3GPP TS 25.331V6.4.0", it is at a loss; Regarding the configuration information of signature and UpPTS time slot resources, the UE cannot understand the configuration information according to the definition and usage method in the protocol "3GPP TS 25.224V6.3.0", and the configuration information cannot play its due role. When the UE performs the random access process, the method of using the signature and the UpPTS time slot resource is in an uncertain state, which is out of the control of the system. In this way, in the TD-SCDMA system, it is impossible to implement the method described above to control different UEs to achieve different access service qualities by configuring different ASCs and corresponding signatures and UpPTS time slot resources.

Contents of the invention

The technical problem solved by the present invention is that there is inconsistency between the configuration methods of signature and UpPTS time slot resources in the prior art, so that the system cannot control different UEs by configuring different ASCs and corresponding signatures and UpPTS time slot resources. Different access quality of service.

In order to solve the above-mentioned technical problems, the present invention proposes a random access method, comprising the following steps:

1) The physical layer of the terminal equipment side receives the random access channel transmission request from the media access control layer, triggering the start of the random access process of the physical layer, and the media access control layer inputs the following information: the transmission format used by the physical random access channel message , the access service level of the random access process, and the transmitted data;

2) The terminal device uniquely selects a random access transmission channel according to the transmission format indicated by the media access control layer;

3) The terminal device randomly selects an uplink synchronization sub-channel and a signature from the available uplink synchronization sub-channels and signatures of a given access service level, wherein the random function makes each option have the same possibility of selection;

4) The terminal device determines the appropriate transmit power, and transmits the signature on the selected uplink synchronous sub-channel;

5) The terminal device selects to monitor the forward physical access channel;

6) The terminal device receives the network-side access confirmation information on the forward physical access channel, completes uplink synchronization, and selects a physical random access channel to send information on the random access channel.

If a random access conflict occurs, or the terminal device does not receive network-side access confirmation information on the forward physical access channel in step 6, return to step 3.

If a random access conflict occurs, or the terminal device does not receive the network-side access confirmation information on the forward physical access channel in the step 6, when the terminal device retransmits the signature, it starts from the given access service level Randomly select a signature from the available signatures, the uplink synchronization sub-channel remains unchanged, and return to step 4.

If a random access conflict occurs, or the terminal device does not receive the network-side access confirmation information on the forward physical access channel in the step 6, when the terminal device retransmits the signature, it starts from the given access service level Randomly select an uplink synchronization sub-channel from the available uplink synchronization sub-channels, the signature remains unchanged, and return to step 4.

The beneficial effects of the present invention are: the uplink pilot time slot and the uplink synchronization sub-channel in the TD-SCDMA system of the present invention are clearly configured, and a corresponding random access method is provided, which solves the problem of TD-SCDMA wireless communication in the current 3GPP. In the protocol of the communication system, the definition and selection method of the signature used in the random access process and the UpPTS time slot resource are inconsistent with the configuration method. On the one hand, the system can use the protocol "3GPP TS 25.331V6. On the other hand, the UE can correctly understand the configuration of the signature and UpPTS time slot resources by the system, and use the signature and UpPTS time slot resources according to the configuration information, so that the system can control the UE to use the signature and UpPTS time slot resources. Purpose of the UpPTS slot resource. At the same time, just because the system can control UEs to use signatures and UpPTS time slot resources, the system can control different UEs to achieve different access service qualities by configuring different ASCs and corresponding signatures and UpPTS time slot resources.

Description of drawings

Figure 1 is a schematic diagram of the structure of the ASC setting information unit

Fig. 2 Schematic diagram of the UpPCH subchannel of the UpPTS time slot when N=8 in the system of the present invention

FIG. 3 is a flow chart of an embodiment of the random access method on the UE side of the present invention

Detailed ways

The specific implementation of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 2 is the UpPCH subchannel schematic diagram of the UpPTS time slot of the TD-SCDMA system of the present invention, the number N of UpPCH subchannels is configured as 8 in this example, and the uplink pilot time slot includes 8 subchannels, numbered from 0 to 7.

When SFN'mod 8=0, the UpPTS slot of the subframe is the 0th subchannel;

When SFN'mod 8=1, the UpPTS slot of the subframe is the first subchannel;

When SFN'mod 8=7, the UpPTS time slot of the subframe is the seventh subchannel;

Wherein, SFN is the system frame number used for counting the number of frames, and the value range is 0-4095. The SFN increases by 1 for each wireless frame, and counts cyclically between 0-4095.

SFN' is the subframe number used to count the number of subframes, and each wireless subframe increases by 1. When the frame with the system frame number SFN=0 starts, SFN' is set to 0. In the TD-SCDMA system, a radio frame includes two radio subframes.

In the present invention, the UpPCH subchannel in the TD-SCDMA system is configured as an UpPTS time slot resource related to the subframe, and the UpPCH subchannel resource and the signature resource in the random access process are separated. In the random access process, the selection of the signature and sub-channel resources are independently randomly selected. Moreover, when a random access conflict occurs, each time the UE retransmits the uplink synchronization code, it also needs to randomly select an UpPCH sub-channel and an UpPCH sub-channel respectively. One signature, or the UpPCH sub-channel remains unchanged, and only one signature is randomly selected, or the signature remains unchanged, and only one UpPCH sub-channel is randomly selected. In the configuration method of UpPCH sub-channel resources and signature resources, the configuration method in the current protocol "3GPP TS 25.331V6.4.0" is still adopted, and the signature and UpPCH sub-channel resources are configured independently in the ASC setting information unit.

As shown in Figure 3, the specific process of the UE side random access method is as follows:

1) The physical layer on the UE side receives a random access channel (RACH) transmission request from the media access control layer MAC (Media Access Control), which triggers the start of the random access process at the physical layer. The information input by the MAC layer includes: the information used by the PRACH message Transmission format; access service class ASC of random access procedure; transmitted data (transport block set);

2) According to the transmission format indicated by the MAC layer, a RACH transmission channel is uniquely selected;

3) Select a sub-channel according to the ASC: the selection method is to randomly select an UpPCH sub-channel from the available UpPCH sub-channels of a given ASC, wherein the random function will make each option have the same selection possibility;

4) Select a signature according to ASC: the selection method is to randomly select a signature from the available signatures of a given ASC, and the random function will make each option have the same possibility of being selected;

5) Transmit the signature on the selected sub-channel;

6) Select to monitor the forward physical access channel (FPACH);

7) Judging whether the network side access confirmation information is received on the FPACH channel; if not received, skip to step 3) or step 4); if received, skip to step 8;

8) The uplink synchronization is completed, and the PRACH physical channel is selected to send information on the RACH channel.

9) The process ends.

The above steps 3) and 4) can be interchanged, that is to say, the signature can be selected first and then the UpPCH sub-channel can be selected.

Claims (7)

1. a random access method of time division duplex code division multiple access system, it is characterized in that comprising the following steps: 5.1) The physical layer of the terminal device side receives the random access channel transmission request from the media access control layer, which triggers the start of the random access process of the physical layer, and the media access control layer inputs the following information: the transmission format used by the physical random access channel message , the access service level of the random access process, and the transmitted data; 5.2) The terminal device uniquely selects a random access channel according to the transmission format indicated by the media access control layer; 5.3) The terminal device randomly selects an uplink synchronization sub-channel and an uplink synchronization code from the available uplink synchronization sub-channels and uplink synchronization codes of a given access service level, and the random function makes each option have the same selection possibility; 5.4) The terminal device determines the appropriate transmission power, and transmits the uplink synchronization code on the selected uplink synchronization sub-channel; 5.5) The terminal device chooses to monitor the forward physical access channel; 5.6) The terminal device receives the network-side access confirmation information on the forward physical access channel, completes uplink synchronization, and selects a physical random access channel to send information on the random access channel. 2. the random access method of time division duplex code division multiple access system as claimed in claim 1, it is characterized in that, if random access conflict occurs, or in said step 5.6 terminal equipment is on the forward physical access channel If the network side access confirmation message is not received, return to step 5.3. 3. the random access method of time division duplex code division multiple access system as claimed in claim 1, it is characterized in that, if random access conflict occurs, or in said step 5.6 terminal equipment is on the forward physical access channel If the network side access confirmation information is not received, when the terminal device retransmits the uplink synchronization code, it randomly selects an uplink synchronization code from the uplink synchronization codes available for a given access service level, and the uplink synchronization sub-channel remains unchanged. Return to step 5.4. 4. the random access method of time division duplex code division multiple access system as claimed in claim 1, is characterized in that, if random access conflict occurs, or in described step 5.6 terminal equipment is on the forward physical access channel If the network side access confirmation information is not received, when the terminal device retransmits the uplink synchronization code, it randomly selects an uplink synchronization subchannel from the uplink synchronization subchannels available for a given access service level, and the uplink synchronization code remains unchanged. , return to step 5.4. 5. The random access method of a time division duplex code division multiple access system according to claim 1, 2, 3 or 4, wherein the uplink synchronization sub-channel is located in the uplink pilot time slot. 6. the random access method of time division duplex code division multiple access system as claimed in claim 5, it is characterized in that, wherein, the uplink pilot time slot is configured into N uplink synchronous sub-channels, numbered from 0 to N-1 , where N takes the value of 1 or 2 or 4 or 8. 7. the random access method of time division duplex code division multiple access system as claimed in claim 6, it is characterized in that, the ith uplink synchronous subchannel of uplink pilot time slot is the uplink pilot that subframe number satisfies the following conditions Frequency slot: SFN' mod N=i, where SFN' is the subframe number used to count the number of subframes. When the frame with system frame number SFN=0 starts, SFN' is set to 0.

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