KR100956311B1 - Method for random access - Google Patents

Abstract

A method for a composite automatic retransmission request operation of downlink packets during a random access procedure to a base station is disclosed.

The base station assigns an identifier within the base station to the received random access preamble and transmits a response message including the identifier information and the uplink control information to the mobile station. The base station receives a connection request message including a unique identifier of the mobile station through an uplink channel and allocates a downlink confirmation channel to the mobile station using the unique identifier. In addition, the base station transmits the access establishment message for the access request message and the information on the downlink confirmation channel from the mobile station, and receives the confirmation message for the access establishment message through the confirmation channel.

OFDMA, HARQ, random access, uplink, downlink

Description

Random access method {METHOD FOR RANDOM ACCESS}

The present invention relates to a random access method in a wireless communication system. In particular, the present invention relates to a method of providing a HARQ confirmation channel for HARQ operation of a downlink channel during a random access procedure of a wireless communication system.

The present invention is derived from the research conducted as part of the IT growth engine technology development of the Ministry of Information and Communication and the Ministry of Information and Communication Research and Development (Task Management Number: 2005-S-404-13, Task name: 3G Evolution wireless transmission technology development).

In a mobile communication system using Orthogonal Frequency Division Multiplexing / Frequency Division Multiple Access (OFDMA) for high-speed, high-speed data transmission, a downlink is a path for a base station to transmit a data packet to a terminal, and the transmitted data packet is a downlink packet to be.

In the Automatic Repeat Request (ARQ) scheme, the UE checks whether the received downlink packet is in an error state and, if an error is detected, the UE requests retransmission of the downlink packet to the base station.

The hybrid high speed downlink packet (HARQ) method is a method of controlling errors by combining a retransmission request according to the automatic retransmission request method and a forward error correction request made in a physical layer. In OFDMA systems, a complex automatic retransmission request scheme is introduced to improve throughput.

In order to communicate with a base station in a mobile communication system, a terminal attempts to connect with a base station. After access, the base station controls the terminal. At this time, the upper layer (RRC layer) of the component layer of the mobile communication system is responsible for access to the system and resource management of the entire system. In addition, the lower layer (MAC layer, physical layer) of the component layer of the mobile communication system is responsible for the short-term radio resource management considering the channel conditions and the transmission and reception of data using radio resources. Therefore, the access to the system should exchange messages for access request and connection establishment between the base station and the terminal higher layer.

The random access method of the access method is a method mainly used for transmission of messages generated during initial access to the system or uplink data transmission of intermittent characteristics. The random access method is a method in which terminals randomly transmit packets with the same transmission authority without control of the base station.

In the OFDMA system for broadband high-speed data transmission, a random access scheme is used in which a preamble using a code distinguishable from each other is first transmitted at a lower layer before transmitting a connection request message packet of a higher layer.

However, when the random access preamble is selected by the terminal without the control of the base station, the same preamble may be selected between different terminals. If there are terminals that select the same preamble, the base station recognizes one terminal and transmits the uplink resource allocation and the terminal of the preamble response including this information.

When several UEs that select the same preamble transmit access request message packets of each RRC layer using radio resources allocated to the preamble, collisions may occur between the access request message packets. Alternatively, even when a terminal having the same preamble exists, only a connection request message of one terminal may be properly transmitted to a higher layer of the base station due to a difference in radio environment between the terminals. In this case, the upper layer (RRC layer) of the base station determines the terminal attempting to access as one, and transmits a message packet for transmitting the information necessary for the connection configuration in downlink. The connection setup message can be received by all terminals that have selected the same preamble. Therefore, when transmitting and receiving data packets, collisions may occur between the HARQ check channel and subsequent packet transmission and reception between several terminals that receive the same connection establishment message.

The technical problem to be achieved by the present invention is a downlink HARQ operation so that when the terminal performs the random access procedure to the base station, the base station does not distinguish between the terminal using the same preamble, HARQ check channel and packet collision does not occur It is to provide a method of allocating a HARQ check channel of the random access method for.

According to an aspect of the present invention, a random access providing method of a base station includes: assigning an identifier to a random access preamble, transmitting a response message including identifier information and uplink control information to the mobile station, and unique identifier of the mobile station. Receiving an access request message including an uplink channel, allocating a downlink confirmation channel to the mobile station by using the unique identifier, an access establishment message for the access request message and the downlink Transmitting information about an acknowledgment channel to the mobile station and receiving an acknowledgment message for the connection establishment message via the acknowledgment channel.

According to another aspect of the present invention, a random access method of a mobile station includes transmitting a random access preamble to a base station, and receiving a response message including identifier information and uplink control information allocated to the random access preamble. Transmitting a connection request message including a unique identifier of the mobile station through the uplink; confirming confirmation channel information using the unique identifier; a connection establishment message for the connection request message and the confirmation channel Receiving information on the and transmitting the confirmation message for the connection establishment message via the confirmation channel.

As described above, according to the embodiment of the present invention, in the OFDMA mobile communication system, when the UE performs the random access procedure to the base station, HARQ confirmation channel collision does not occur because the base station cannot distinguish between the UEs using the same preamble. Do not In addition, the method of providing a HARQ confirmation channel among random access methods can prevent a collision of packets generated by a plurality of mobile stations using the same channel resource after the connection establishment message.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art may easily implement the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is said to "include" a certain component, it means that it can further include other components, without excluding other components unless specifically stated otherwise. In addition, the terms “… unit”, “… unit”, “module”, etc. described in the specification mean a unit that processes at least one function or operation, which may be implemented by hardware or software or a combination of hardware and software. have.

In this specification, a mobile station (MS) is a terminal, a mobile terminal (MT), a subscriber station (SS), a portable subscriber station (PSS), a user equipment (User Equipment). It may also refer to a user equipment (UE), an access terminal (AT), and the like, and may include all or some functions of a mobile terminal, a subscriber station, a portable subscriber station, a user device, and the like.

In the present specification, a base station (BS) is an access point (AP), a radio access station (Radio Access Station, RAS), a Node B (Node B), a base transceiver station (Base Transceiver Station, BTS), MMR ( Mobile Multihop Relay) -BS and the like, and may include all or part of functions such as an access point, a radio access station, a Node B, a base transceiver station, and an MMR-BS.

1 is a diagram illustrating a downlink HARQ operation of a random access procedure according to an embodiment of the present invention.

As shown in Fig. 1, in order to connect to the system, the lower layer of the mobile station 100 transmits a random access preamble to the base station 200 (S101). Upon receiving the random access preamble, the base station 200 assigns an identifier (for LTE, C-RNTI) that can be distinguished in the base station 200 to the preamble. The identifier is used for radio resource allocation in the base station 200. Specifically, when the identifier is changed or the connection with the base station is released, the identifier may be recovered from the base station and reassigned to another mobile station. In addition, the same separator may exist for each base station. The base station maintains mapping relationship information between the identifier in the base station of the mobile station and the identifier unique to the mobile station.

The base station 200 transmits downlink control information (DL CI) to the mobile station 100 so that the mobile station 100 can receive a response message for the preamble (S102). The base station 200 transmits a response message for the received preamble to the mobile station 100 (S103). The mobile station 100 recognizes the identifier information included in the response message as its own identifier in the base station 200. At this time, the base station 200 displays the downlink control information as an identifier and transmits it to the mobile station 100. The downlink control information includes allocation information and control related information for each uplink data channel.

The mobile station 100 transmits an access request message to the base station 200 using the uplink resource information included in the response message for the preamble received through the downlink control information (S104). Here, the connection request message includes information such as a unique identifier in the base station 200 of the mobile station 100, a reason for connection, and the like. In addition, the upper layer access request message transmitted by the mobile station 100 to the base station 200 includes a unique identifier (for GSM-based core network, p-TMSI + RAI, TMSI + LAI, IMSI) in the entire system.

After checking whether the access request message is in error, the base station 200 transmits a HARQ confirmation message to the mobile station 100 when there is no error (S105).

The base station 200 allocates an acknowledgment channel (ACK_cid) to the mobile station 100 using the unique identifier of the mobile station 100 provided from the upper layer in the lower layer that is responsible for the allocation of radio resources in a short period (S106). The confirmation channel is a response transmission channel for the HARQ operation, the base station 200 determines the identifier of the confirmation channel as shown in Equation 1.

When assigning the confirmation channel, a plurality of confirmation channels can be selected according to the unique identifier of the mobile station 100, and the base station 200 selects one of the confirmation channels that are not assigned to other mobile stations.

The base station 200 transmits downlink control information to the mobile station 100 (S107). In this case, the downlink control information includes allocation information, control related information, and confirmation channel information for each downlink data channel.

The base station 200 transmits a connection establishment message to the mobile station 100 (S108). The mobile station 100 transmits an HARQ acknowledgment message corresponding to the access establishment message to the base station 200 through the acknowledgment channel (S109).

Next, the downlink HARQ operation during the random access procedure of the base station 200 according to an embodiment of the present invention will be described in detail with reference to FIG. 2.

2 is a diagram illustrating downlink HARQ operation during a random access procedure of a base station according to an embodiment of the present invention.

As shown in FIG. 2, the base station 200 determines whether a random access preamble is received (S201). In addition, upon receiving the random access preamble, the base station 200 assigns an identifier to the preamble.

When the base station 200 receives the random access preamble, the base station 200 displays the response confirmation message for the received preamble and the downlink control information for receiving the response confirmation message as the assigned identifiers and transmits them to the mobile station 100. (S202).

The base station 200 receives the access request message through the uplink control information included in the response acknowledgment message for the preamble (S203). Here, the connection request message includes information such as a unique identifier in the base station 200 of the mobile station 100, a reason for connection, and the like. The base station 200 determines whether the received access request message is an error (S204). If there is no error in the access request message, the base station 200 transmits an acknowledgment channel response message for the uplink to the mobile station 100 (S205).

If there is an error in the access request message, the base station 200 compares the maximum number of retransmissions with the number of transmissions (S206). If the comparison result is not the same, the base station 200 transmits an uplink control information message for retransmission of the access request message of the mobile station 100 (S207). The base station 200 allocates a confirmation channel for the downlink of the mobile station 100 using the unique identifier based on the access request message of the mobile station 100 (S208).

The base station 200 assigned the confirmation channel transmits a downlink control information message and a connection establishment message to the mobile station 100 (S209).

The base station 200 determines whether an acknowledgment is received through the confirmation channel for the downlink (S210). Here, the acknowledgment is a reception response of HARQ feedback information corresponding to the downlink message packet. When receiving the acknowledgment, the base station 200 receives the uplink message of the mobile station (S211). On the other hand, if not receiving the acknowledgment, the base station 200 compares the number of transmissions and the maximum number of transmissions (S212).

The base station 200 determines whether the received uplink message is in error (S213). If there is no error in the uplink message, the base station 200 makes the mobile station 100 transition to the state connected to the system (S214). If there is an error in the uplink message, the base station 200 compares the maximum number of retransmissions with the number of receptions (S215). If the comparison is not the same, the base station 200 transmits an uplink control message for retransmission (S216).

Next, HARQ operation of the downlink during the random access procedure of the mobile station 100 according to an embodiment of the present invention will be described in detail with reference to FIG. 3.

3 is a diagram illustrating HARQ operation of a downlink during a random access procedure of a mobile station according to an embodiment of the present invention.

As shown in FIG. 3, the mobile station 100 transmits a random access preamble to the base station 200 (S301). The mobile station 100 determines whether a response confirmation message for the transmitted preamble is received (S302). At this time, the mobile station 100 receives downlink control information for receiving a response confirmation message and a response confirmation message.

When receiving the response confirmation message, the mobile station 100 transmits the access request message to the base station 200 based on the uplink control information included in the response to the preamble (S303).

The mobile station 100 determines whether to receive a confirmation channel response to the transmitted connection request message (S304). If the acknowledgment channel response is not received, the mobile station 100 compares the number of transmissions with the maximum number of transmissions (S311). Upon receiving the acknowledgment, the mobile station 100 checks whether the downlink control information has been received (S305). At this time, it is determined whether an acknowledgment is received through the confirmation channel according to the confirmation channel information included in the downlink control information. If the downlink control information is not received, the mobile station 100 compares the timer value with the maximum timer value (S312).

Upon receipt of the acknowledgment through the acknowledgment channel, the mobile station 100 confirms the information on the acknowledgment channel for the downlink included in the downlink control information message (S306).

The mobile station 100 receives a connection establishment message based on the downlink control information (S307). The mobile station 100 determines whether the received connection establishment message is in error (S308). If there is an error in the connection establishment message, the mobile station 100 compares the timer value with the maximum timer value (S313). If there is no error in the connection establishment message, the mobile station transmits a confirmation message for the connection establishment message (S309).

The mobile station 100 that transmits the confirmation message determines that the connection is completed to the base station 200, and makes a transition to the connected state (S310).

The embodiments of the present invention described above are not only implemented by the apparatus and method but may be implemented through a program for realizing the function corresponding to the configuration of the embodiment of the present invention or a recording medium on which the program is recorded, The embodiments can be easily implemented by those skilled in the art from the description of the embodiments described above.

Although the embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements of those skilled in the art using the basic concepts of the present invention defined in the following claims are also provided. It belongs to the scope of rights.

1 is a diagram illustrating a downlink HARQ operation of a random access procedure according to an embodiment of the present invention.

2 is a diagram illustrating downlink HARQ operation during a random access procedure of a base station according to an embodiment of the present invention.

3 is a diagram illustrating HARQ operation of a downlink during a random access procedure of a mobile station according to an embodiment of the present invention.

Claims (7)

In the random access providing method of the base station, Assigning an identifier for identifying the mobile station to the random access preamble; Transmitting a response message including the identifier and uplink control information to a mobile station; Receiving a connection request message on the uplink channel including a unique identifier of the mobile station; Allocating a downlink confirmation channel to the mobile station using the unique identifier; Transmitting a connection establishment message for the access request message and information on the downlink confirmation channel to the mobile station; And And receiving a confirmation message for the connection establishment message through the confirmation channel. The method of claim 1, The step of transmitting the response message to the mobile station And receiving the random access preamble, including the identifier and the uplink control information in a response acknowledgment message for the preamble to the mobile station. The method of claim 1, Allocating an identifier to the random access preamble Receiving the random access preamble from the mobile station; And assigning an identifier to the random access preamble. The method of claim 1, Receiving the access request message through the uplink channel Determining whether the access request message is in error; And if there is no error, transmitting an acknowledgment channel response message for uplink to the mobile station. In the random connection method of the mobile station, Transmitting a random access preamble to a base station; Receiving a response message including an identifier for identifying the mobile station allocated to the random access preamble and uplink control information; Transmitting on the uplink a connection request message comprising a unique identifier of the mobile station; Confirming confirmation channel information using the unique identifier; Receiving a connection establishment message for the connection request message and information on the confirmation channel; And And transmitting an acknowledgment message for the connection establishment message through the acknowledgment channel. The method of claim 5, The step of transmitting the random access preamble to the base station is Determining whether to receive a response acknowledgment message for the preamble; Receiving the response acknowledgment message, receiving the identifier and uplink control information. The method of claim 5, The step of transmitting the access request message on the uplink Determining whether the access request message is in error; And if there is no error in the access request message, transmitting an access confirmation message for the access request message.

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