KR100662283B1 - Method for Accessing randomly in Time Division Duplex Mode - Google Patents

Abstract

The present invention relates to a next-generation mobile communication system, in particular, time division duplex in which transmission of an uplink pilot time slot (UpPTS) in a time division duplex (TDD) mode having a low chip rate causes fewer collisions between users. It relates to a random access method in the (TDD) mode. The random access method in the time division duplex mode according to the present invention comprises the steps of selecting a service identifier according to the priority of the data in which the user the data to be transmitted; One of the subframes according to the selected service identifier and one of the code sequences assigned to the subframe are selected to transmit the specific code sequence to the base station through an uplink pilot time slot (UpPTS) of the selected subframe. Transmitting; And transmitting the data to a predetermined channel using a time slot and a channelization code mapped to the selected subframe and a specific code sequence according to a response signal of the base station to the transmitted UpPTS. Accordingly, the present invention utilizes the concept of ASC to enable random access by dividing a high priority service or a low priority service.

Access service class (ASC), SYNC1, physical random access channel (PRACH)

Description

Random access method in time division duplex mode {Method for Accessing randomly in Time Division Duplex Mode}

1 illustrates a radio frame structure in a typical 1.28 Mcps time division duplex (TDD) mode.

FIG. 2 is a diagram illustrating a structure of an UpPTS among timeslots constituting a radio frame shown in FIG. 1. FIG.

The present invention relates to a next-generation mobile communication system, in particular, time division duplex in which transmission of an uplink pilot time slot (UpPTS) in a time division duplex (TDD) mode having a low chip rate causes fewer collisions between users. It relates to a random access method in the (TDD) mode.

The ITU suggested that Time Division Duplex (TDD) mode with low chip rate (1.28 Mcps) should be supported even in indoor, walking and transport environments (120 km / h). The low chip rate option, one of the TDD options, must support basic service (bearer service), support 2Mbps data service in IMT-2000 compliant systems and indoor environments that meet ITU requirements, and in outdoor walking environments. In addition, data services must be supported up to 384 kbps or higher, and data rates for moving users (at least 120 km / h of vehicle speed) must be supported at 384 kbps or higher.

In the physical layer in the TDD mode having the low chip rate, the power control operation, the cell search operation, and the uplink control for the closed power control in the TDD mode having the low chip rate in both uplink and downlink Synchronization, random access, beamforming (optional), etc. are different or additionally required procedures from TDD mode with high chip rate (3.84 Mbps or more).

In particular, the sub frame structure in the TDD mode having a low chip rate has technical considerations for beamforming or uplink synchronization described above.

1 is a diagram illustrating a radio frame structure in a general 1.28 Mcps time division duplex (TDD) mode.

Referring to FIG. 1, a radio frame in a TDD mode having a low chip rate has a length of 10 ms, and the radio frame includes two sub frames having a length of 5 ms (6400 chips). The subframe is divided into seven traffic slots and three time slots with special functions. In the TDD mode having a low chip rate, the frame structure is appropriately divided into uplink or downlink time slots so that a symmetrical or asymmetrical structure is provided. Can be operated. In this case, each of the seven slots is assigned a slot number (TsN; N is an integer increasing from 0 to 6), wherein the Ts0 time slot is a downlink and a Ts1 time slot is allocated uplink. In addition, three time slots with special functions are located between the time slots of Ts0 and Ts1. A guard period (GP) and a downlink pilot time slot (DwPTS) are located in a subframe. It is fixedly located after the Ts0 time slot so that the user does not lose synchronization, and the base station Node B performs the synchronization procedure (via the DwPTS channel). It also prevents users transmitting Uplink Pilot Time Slots (UpPTSs) from disturbing users transmitting DwPTS of other users.

FIG. 2 is a diagram illustrating a structure of an UpPTS among time slots constituting the radio frame shown in FIG. 1.

Referring to FIG. 2, the UpPTS includes a SYNC1 field (128 chips) and a GP field (32 chips). The UpPTS is a time slot having a total length of 125us, and a user may send the UpPTS once every 5ms subframe. Here, SYNC1 is composed of an orthogonal gold sequence of 128 chips, and eight orthogonal gold codes having a code length of 8 per base station (or cell) are allocated.

After measuring transmission timing and power level of the UpPTS, the base station Node B issues transmission timing adjustment and power adjustment command through a downlink fast physical access channel (FPACH). This information allows the user to signal at the correct transmission timing and power over the physical random access channel (PRACH) in uplink.

However, in the prior art, since one SYNC1 code is selected from the UpPTS transmitted uplink every 5ms, when a large number of users attempt random access, the users attempt random access, thereby increasing the probability of an access collision. There is a problem.

Accordingly, an object of the present invention has been made in view of the above-mentioned problems of the prior art, and the access subframe group according to the service identifier (ASC Indicator) assigned to a specific user is selected for a subframe through which UpPTS is transmitted and SYNC1. It is an object of the present invention to provide a random access method in a time division duplex mode that is determined according to a subframe and an SYNC1 mapping relationship in (AG).

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According to a method feature of the present invention for achieving the above object, the step of selecting a service identifier according to the priority of the data generated by the user to the data to be transmitted; One of the subframes according to the selected service identifier and one of the code sequences assigned to the subframe are selected, and the base station receives the selected code sequence through an uplink pilot time slot (UpPTS) of the selected subframe. And transmitting the data to the base station by using a time slot and a channelization code according to a response signal of the base station for the transmitted UpPTS.
Preferably, the subframes according to the service identifier are composed of a continuous subframe group having a predetermined number, and each subframe in the subframe group is assigned at least one or more code sequences. In this case, the information on the subframe group according to the service identifier and the code sequences allocated to each subframe in the subframe group is transmitted to the user through a message of the radio resource control (RRC) layer.
Another aspect of an embodiment of the present invention includes: obtaining identifier information for identifying a mobile terminal in which data to be transmitted has occurred; Selecting one of a plurality of consecutive subframes indicated by the obtained identifier and one of a plurality of code sequences indicated by the identifier for the subframe; Transmitting the selected code sequence using a predetermined time slot of the selected subframe; And transmitting the data to a specific channel using an arbitrary time slot and channelization code in response to the transmitted code sequence.
Hereinafter, a configuration and an operation according to an exemplary embodiment of the present invention will be described with reference to the accompanying drawings.

As described in the prior art, a radio frame in a TDD mode having a low chip rate is 10ms long, and the radio frame is composed of two subframes 5ms (6400 chips) long. The subframe is divided into seven traffic slots and three time slots with special functions, where each slot number (TsN; N is an integer increasing from 0 to 6) is assigned to the seven slots. The Ts0 time slot is a time slot allocated to the downlink and the Ts1 time slot is assigned to the uplink. In addition, three time slots with special functions are located between the time slots of Ts0 and Ts1. A guard period (GP) and a downlink pilot time slot (DwPTS) are located in a subframe. It is fixedly located after the Ts0 time slot so that the user does not lose synchronization, and the base station Node B performs the synchronization procedure (via the DwPTS channel). In addition, users who transmit uplink pilot time slots (UpPTSs) do not interfere with users who transmit DwPTS of other users.

The UpPTS consists of a SYNC1 field (128 chips) and a GP field (32 chips). The UpPTS is a time slot having a total length of 125us, and a user may send the UpPTS once every 5ms subframe. Here, SYNC1 is composed of an orthogonal gold sequence of 128 chips, and eight orthogonal gold codes having a code length of 8 per base station (or cell) are allocated.

Therefore, in the present invention, the surf frames are grouped by M and operated as one Access sub-frame group (AG). That is, one AG is composed of consecutive M subframes. In this case, M corresponds to a positive integer. For example, when M = 4, one AG consists of four consecutive subframes. M subframes in the AG are mapped to an Access Service Class (ASC). In this case, the ASC is to give priority to a service for each user, and each ASC is an indicator indicating certain parts of physical random access channel (PRACH) resources (time slots and channelization codes). The indicator is an integer between 0 and NumASC and has a value between 0 and 7) and a resistance value (the probability of transmission).

In the present invention, each ASC is mapped to one or a plurality of subframes in the AG and one or a plurality of SYNC1 codes in the subframe. In this case, a plurality of AGs may be mapped to the same subframe and the same SYNC1 code.

In the present invention, a combination of a subframe in which UpPTS is transmitted and a SYNC1 code indicates one or a plurality of PRACH resources. In the present invention, a PRACH resource includes a time slot and a channelization code in which a PRACH burst is transmitted. However, the subframe in which the PRACH burst is transmitted may be included in the PRACH resource. At this time, the PRACH burst is selected and transmitted in one subframe in the AG, and the subframe in which the PRACH burst is transmitted is mapped to a combination of the subframe in which UpPTS is transmitted and the SYNC1 code.

In the present invention, all the above mapping relationships are previously transmitted to the user through an RRC message. Therefore, the wireless network and the user share the same mapping information before random access. All mapping relationships described in the configuration of the present invention may be one-to-one mapping relationships, but may also be mapped to one-to-multiple or multiple-to-one relationships. Table 1 below is an example of a mapping relationship between subframes and SYNC1 codes in ASC and AG.

ASC AG First subframe Second subframe Third subframe Fourth subframe Indicator = 0 N th SYNC1 N + 1 th SYNC1 N + 2 th SYNC1 N + 3 th SYNC1 N + 4th SYNC1 N + 5th SYNC1 N + 6th SYNC1 N + 7th SYNC1 Indicator = 1 N th SYNC1 N + 1 th SYNC1 N + 2 th SYNC1 N + 3 th SYNC1 N + 4th SYNC1 N + 5th SYNC1 N + 6th SYNC1 N + 7th SYNC1 Indicator = 2 N + 4th SYNC1 N + 5th SYNC1 N + 6th SYNC1 N + 7th SYNC1 N th SYNC1 N + 1 th SYNC1 N + 2 th SYNC1 N + 3 th SYNC1 Indicator = 3 N + 4th SYNC1 N + 5th SYNC1 N + 6th SYNC1 N + 7th SYNC1 N th SYNC1 N + 1 th SYNC1 N + 2 th SYNC1 N + 3 th SYNC1

ASC AG First subframe Second subframe Indicator = 0 Nth SYNC1 N + 1st SYNC1 N + 2th SYNC1 N + 3th SYNC1 N + 4th SYNC1 N + 5th SYNC1 N + 6th SYNC1 N + 7th SYNC1 Indicator = 1 Nth SYNC1 N + 1st SYNC1 N + 2th SYNC1 N + 3th SYNC1 N + 4th SYNC1 N + 5th SYNC1 N + 6th SYNC1 N + 7th SYNC1 Indicator = 2 Nth SYNC1 N + 1st SYNC1 N + 2th SYNC1 N + 3th SYNC1 N + 4th SYNC1 N + 5th SYNC1 N + 6th SYNC1 N + 7th SYNC1

The random access procedure according to the present invention is as follows.

The user's MAC layer and the physical layer receive control parameters for random access from the RRC layer. Control parameters include ASC related parameters, transmit power, and random backoff values for when random access fails.

That is, the MAC layer and the physical layer of the user includes at least one subframe mapped to this ASC indicator with an ASC indicator which is a value assigned to each user in order to give the user a random access opportunity according to priority in the RRC layer, Each of these subframes is also sent with information about the mapping relationship with at least one or more SYNC1 codes. Here, the mapping relationship between the ASC indicator, the subframe, and the SYNC1 codes may be given as shown in Table 1 or Table 2, and although not shown in Tables 1 and 2, at least one PRACH in the present invention depends on the mapping relationship. Indicates resource information (time slot, channelization codes).

The user selects the ASC when the data to be sent occurs. At this time, the user selects a specific indicator (which has a value between 0 and NumASC) and a resistance value.

The user selects one subframe and one SYNC1 code from AG among subframes and SYNC1 codes mapped to the selected ASC.

The user transmits UpPTS in the SYNC1 code with the selected subframe in the AG.

When receiving a NACK from the FPACH, the user selects one subframe and one SYNC1 code among the subframes and the SYNC1 codes mapped to the previously selected ASC after the backoff, and retransmits the UpPTS. Retransmission of UpPTS continues until an ACK is received from the FPACH. The number of retransmissions in UpPTS is set by RRC.

When receiving an ACK from the FPACH, the PRACH burst is transmitted in a time slot and a channelization code mapped to the subframe used for UpPTS transmission and the SYNC1 code.

On the other hand, when a subframe in which a PRACH burst is transmitted with a time slot and a channelization code is mapped to a subframe used for UpPTS transmission and a SYNC1 code, the subframe in which a PRACH burst is transmitted is a subframe used for UpPTS transmission. The frame and the SYNC1 code are selected from the mapped subframes. That is, the PRACH burst is transmitted from among the M subframes in the AG from among the subframes used for UpPTS transmission and the subframes mapped to the SYNC1 code.

As described above, the present invention uses the SYNC1 code of one subframe of the M subframes available in the AG according to the assigned ASC, rather than the method of using the UpPTS every 5ms. The method used reduces the probability of collision, and this method makes use of the concept of ASC to distinguish between high-priority or low-priority services for random access.

Those skilled in the art will appreciate that various changes and modifications can be made without departing from the spirit of the present invention.

Therefore, the technical scope of the present invention should not be limited to the contents described in the examples, but should be defined by the claims.

Claims (5)

Selecting a service identifier according to the priority of the corresponding data by the user having the data to be transmitted; One of the subframes according to the selected service identifier and one of the code sequences assigned to the subframe are selected, and the base station receives the selected code sequence through an uplink pilot time slot (UpPTS) of the selected subframe. Transmitting to; And transmitting the data to a base station by using a time slot and a channelization code according to a response signal of the base station to the transmitted UpPTS. The method of claim 1, wherein the subframes according to the service identifier are composed of a continuous subframe group having a predetermined number, and each subframe in the subframe group is assigned at least one or more code sequences. Random access method in time division duplex mode. 3. The method of claim 2, wherein the information on the subframe group according to the service identifier and the code sequences assigned to each subframe in the subframe group is transmitted to the user through a message of a radio resource control (RRC) layer. And a random access method in time division duplex mode. The method of claim 1, wherein transmitting the data to the base station, Determining whether the response is ACK or NACK; And If the response is NACK, selecting one of the subframe and code sequence and setting the code sequence are performed again; and if the response is ACK, performing the data transmission. And a random access method in time division duplex mode. The method of claim 1, The time slot and channelization code is determined by the selected subframe and the selected code sequence. A random access method in time division duplex mode characterized by the above-mentioned.

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