WO2016129896A1

WO2016129896A1 - Method and device for channel adaptive random access channel transmission in communication system

Info

Publication number: WO2016129896A1
Application number: PCT/KR2016/001313
Authority: WO
Inventors: 문희찬
Original assignee: 한양대학교 산학협력단
Priority date: 2015-02-09
Filing date: 2016-02-05
Publication date: 2016-08-18

Abstract

The present specification relates to the transmission and the reception of a random access channel in a mobile communication system. A random access channel transmission method according to one embodiment of the present specification can comprise the steps of: receiving, from a base station, one or more pilot signals for the measurement of a channel state; measuring the channel state on the basis of the one or more pilot signals, determining, on the basis of the measured channel state, whether to transmit a random access channel, and determining one transmission resource from among a plurality of transmission resources allocated for the transmission of the random access channel; and transmitting the random access channel to the base station by using the one determined transmission resource, when the transmission of the random access channel is determined.

Description

Method and apparatus for channel adaptive random access channel transmission in communication system

The present invention relates to random access transmission in a mobile communication system, and more particularly, to channel adaptive random access transmission in a broadband communication system.

In a mobile communication system such as a 3GPP W-CDMA (Wideband-Code Division Multiple Access) of ^{(3 rd Generation Partnership Project),} LTE (Long Term Evolution), the LTE-A (Advanced), or 3GPP2 CDMA2000 terminal with a base station A random access procedure can be performed to perform communication. The random access procedure is a procedure for establishing a link with a base station when the terminal does not have a link with the base station. The contention-based random access procedure and the non-contention based random access procedure, etc. It can be carried out by a variety of methods.

In the random access procedure, a UE transmits a random access preamble to a base station through a random access channel, and the base station checks the random access preamble of the UE to transmit a random access response to the UE. It can be performed through.

As described above, a random access channel is an essential element of various wireless communication systems, and various access channels may be implemented. However, regardless of the method of implementing the random access channel, the conventional random access channel immediately transmits an access probe when an event for random access channel transmission occurs in the upper layer regardless of the channel state of the reverse link. However, it has been pointed out that the transmission of the random access channel requires excessive transmission power. This problem may be referred to, for example, by the non-patent document Hichan Moon, Suhan Choi, "Channel adaptive random access for TDD-based wireless system" (IEEE Trans. Vehicular Tech., Pp. 2730-2741, July 2011). Can be.

In order to solve the above problem, in the paper, the state of the forward channel is obtained by measuring the state of the forward channel in a time division duplex (TDD) wireless communication system, and the obtained reverse channel state information satisfies a specific condition. In this case, a method of transmitting a random access channel has been proposed. In the above-described method, the transmission output can be greatly reduced by delaying the transmission of the access probe of the random access channel when the channel condition does not satisfy a specific condition. In addition, the coverage radius of a communication system can be greatly extended under conditions where the maximum or average transmission power is the same. This may be useful in situations where communication with the outside is performed, such as disaster communication.

However, in the channel adaptive random access channel transmission as described above, the time delay required for successfully transmitting the random access can be increased. In particular, this time delay may be a problem in services requiring low time delay. If the threshold for allowing transmission of random access channels (e.g., the threshold of channel conditions) is reduced to reduce time delay, this may degrade the performance of random access.

The present invention devised in the above-described situation is to provide a method and apparatus for performing channel-adaptive random access channel transmission that can improve random access performance and increase communication distance by allocating a plurality of random access transmission resources.

The present invention also provides a method and apparatus for improving random access performance by performing channel measurement using uplink radio resources in a frequency division duplex (FDD) wireless communication system.

The technical problems to be achieved in the present invention are not limited to the above technical problems, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description. .

In one embodiment of the present invention for solving the above problems, a method of transmitting a random access channel of a terminal in a wireless communication system includes receiving one or more pilot signals for measurement of a channel state from a base station. Step, measuring a channel state based on the at least one pilot signal, and whether one of the random access channel transmission and the transmission of one of a plurality of transmission resources allocated for the transmission of the random access channel based on the measured channel state Determining a resource, and if the transmission of the random access channel is determined, transmitting the random access channel to the base station using the determined one transmission resource.

In addition, in a wireless communication system according to another embodiment of the present invention, a terminal for transmitting a random access channel (random access channel) includes a receiver for receiving a signal from a base station, a transmitter for transmitting a signal to the base station, and the receiver and A control unit configured to control a transmission unit, wherein the control unit receives one or more pilot signals for measuring a channel state from the base station, measures a channel state based on the one or more pilot signals, and measures the measurement. Determining whether one random access channel is transmitted and one transmission resource among a plurality of transmission resources allocated for the transmission of the random access channel, and if the transmission of the random access channel is determined, the determined one Further configured to transmit the random access channel to the base station using a transmission resource of Can.

The present invention can provide a more efficient random access channel transmission by allowing the terminal to transmit a random access channel and subsequent messages in some time intervals of the downlink.

In addition, the present invention has the effect that the base station transmits the response to the pilot channel and the access probe in some time period of the uplink can extend the communication distance while reducing the transmission power of the random access channel of the terminal.

1 illustrates a signal transmission structure through an uplink RACH in a mobile communication system.

2 is a diagram exemplarily illustrating a configuration of an access probe.

3 is a diagram illustrating a pilot channel transmitted in CDMA2000 or W-CDMA.

4 illustrates an uplink channel and a downlink channel in an LTE system.

5 is a diagram for describing an operation process of a terminal and a base station in a contention-based random access procedure.

6 is a diagram for describing an operation process of a terminal and a base station in a contention-free random access procedure.

7 shows an example of random access channel transmission in the TDD communication system according to the embodiment 1-1.

8 illustrates an example of random access channel transmission in a TDD communication system according to embodiment 1-2.

9A illustrates an example of random access channel transmission in the FDD-based communication system according to the embodiment 3-1.

9B illustrates an example of random access channel transmission in the FDD-based communication system according to the embodiment 3-2.

9C illustrates an example of random access channel transmission in the FDD-based communication system according to the embodiment 3-3.

10 shows an example of random access channel transmission for a base station having two antennas according to the fourth embodiment.

11A illustrates an example of random access channel transmission for a base station having two antennas according to the embodiment 5-1.

11B illustrates an example of random access channel transmission for a base station having two antennas according to embodiment 5-2.

11C shows an example of random access channel transmission for a base station having two antennas according to the embodiment 5-3.

12 is a diagram illustrating an example of a terminal configuration according to another embodiment of the present invention.

13 is a diagram illustrating another example of a terminal configuration according to another embodiment of the present invention.

14 is a diagram illustrating a configuration of a base station according to another embodiment of the present invention.

15A is a schematic diagram of a base station operating in a TDD mode according to an example.

15B is a schematic diagram of a base station operating in an FDD mode according to another example.

16A is a schematic diagram of a base station operating in an FDD mode according to an example.

16B is a schematic diagram of a base station operating in an FDD mode according to another example.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In the present specification, a MTC terminal may mean a terminal supporting low cost (or low complexity) or a terminal supporting coverage enhancement. In the present specification, the MTC terminal may mean a terminal supporting low cost (or low complexity) and coverage enhancement. Alternatively, in the present specification, the MTC terminal may mean a terminal defined in a specific category for supporting low cost (or low complexity) and / or coverage enhancement.

In other words, in the present specification, the MTC terminal may mean a newly defined 3GPP Release-13 low cost (or low complexity) User Equipment (UE) category / type for performing LTE-based MTC related operations. Alternatively, in the present specification, the MTC terminal supports enhanced coverage compared to the existing LTE coverage, or supports UE category / type defined in the existing 3GPP Release-12 or lower, or newly defined Release-13 low cost (or lower power consumption). low complexity) can mean UE category / type.

The mobile communication system in the present invention is widely deployed to provide various communication services such as voice, packet data, and the like. The mobile communication system includes a user equipment (UE) and a base station (base station, BS, or eNB). In the present specification, a user terminal is a comprehensive concept of a terminal in wireless communication, and may be used in a global system for mobile communication (GSM) as well as user equipment (UE) in WCDMA, LTE, and High Speed Packet Access (HSPA). It should be interpreted as a concept that includes a mobile station (MS), a user terminal (UT), a subscriber station (SS), and a wireless device.

A base station or a cell generally refers to a station for communicating with a user terminal, and includes a Node-B, an evolved Node-B, an Sector, a Site, and a BTS. Other terms such as Base Transceiver System, Access Point, Relay Node, Remote Radio Head (RRH), Radio Unit (RU), Macro Cell, Small Cell Can be.

That is, in the present specification, a base station or a cell is interpreted in a comprehensive sense to indicate some areas or functions covered by a base station controller (BSC) in CDMA, a NodeB in WCDMA, an eNB or a sector (site) in LTE, and the like. It is meant to cover various coverage areas such as mega cell, macro cell, micro cell, pico cell, femto cell and relay node, RRH, RU, small cell communication range.

Since the various cells listed above have a base station for controlling each cell, the base station may be interpreted in two senses. i) A device providing a mega cell, a macro cell, a micro cell, a pico cell, a femto cell, a small cell in relation to a wireless area, or ii) may indicate the wireless area itself. In i) all devices which provide a given wireless area are controlled by the same entity or interact with each other to cooperatively configure the wireless area to direct the base station. According to the configuration of the radio region, an eNB, RRH, antenna, RU, LPN (Local Packet Network), point, transmission point, transmission point, reception point, etc. become one embodiment of a base station. In ii), the base station may indicate the radio area itself that receives or transmits a signal from a viewpoint of a user terminal or a neighboring base station.

Therefore, mega cells, macro cells, micro cells, pico cells, femto cells, small cells, RRHs, antennas, RUs, low power nodes (LPNs), points, eNBs, transmission / reception points, transmission points, and reception points are collectively referred to the base station. Refer.

In the present specification, the user terminal and the base station are two transmitting and receiving entities used to implement the technology or technical idea described in this specification in a comprehensive sense and are not limited by the terms or words specifically referred to. The user terminal and the base station are two types of uplink or downlink transmitting / receiving subjects used to implement the technology or the technical idea described in the present invention, and are used in a generic sense and are not limited by the terms or words specifically referred to. Here, the uplink (Uplink, UL, or uplink) refers to a method for transmitting and receiving data to the base station by the user terminal, the downlink (Downlink, DL, or downlink) means to transmit and receive data to the user terminal by the base station It means the way.

There is no limitation on the multiple access scheme applied to the mobile communication system. Various multiple access techniques such as Code Division Multiple Access (CDMA), Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiple Access (OFDMA), OFDM-FDMA, OFDM-TDMA, OFDM-CDMA Can be used. One embodiment of the present invention is resource allocation in the fields of asynchronous mobile communication evolving to LTE and LTE-advanced through GSM, WCDMA, HSPA, and synchronous wireless communication evolving to CDMA, CDMA-2000 and Ultra Mobile Broadband (UMB). Can be applied to The present invention should not be construed as being limited or limited to a specific mobile communication field, but should be interpreted as including all technical fields to which the spirit of the present invention can be applied.

The uplink transmission and the downlink transmission may use a time division duplex (TDD) scheme that is transmitted using different times, or may use a frequency division duplex (FDD) scheme that is transmitted using different frequencies.

In addition, in a system such as LTE and LTE-A, a standard is configured by configuring uplink and downlink based on one carrier or a pair of carriers. The uplink and the downlink include a Physical Downlink Control CHannel (PDCCH), a Physical Control Format Indicator CHannel (PCFICH), a Physical Hybrid ARQ Indicator CHannel (PHICH), a Physical Uplink Control CHannel (PUCCH), an Enhanced Physical Downlink Control CHannel (EPDCCH), and the like. Control information is transmitted through the same control channel, and data is configured by a data channel such as a physical downlink shared channel (PDSCH) and a physical uplink shared channel (PUSCH).

On the other hand, control information may also be transmitted using an enhanced PDCCH (EPDCCH or extended PDCCH).

In the present specification, a cell means a component carrier having a coverage of a signal transmitted from a transmission / reception point or a signal transmitted from a transmission point or a transmission / reception point, and the transmission / reception point itself. Can be.

A mobile communication system to which embodiments are applied includes a coordinated multi-point transmission / reception system (CoMP system) or a coordinated multi-antenna transmission scheme in which two or more transmission / reception points cooperate to transmit a signal. antenna transmission system), a cooperative multi-cell communication system. The CoMP system may include at least two multiple transmission / reception points and terminals.

The multiple transmit / receive point includes at least one having a base station or a macro cell (hereinafter referred to as an eNB) and a high transmit power or a low transmit power in a macro cell region, which is wired controlled by an optical cable or an optical fiber to the eNB. May be RRH.

In the following, downlink refers to a communication or communication path from a multiple transmission / reception point to a terminal, and uplink refers to a communication or communication path from a terminal to multiple transmission / reception points. In downlink, a transmitter may be part of multiple transmission / reception points, and a receiver may be part of a terminal. In uplink, a transmitter may be part of a terminal, and a receiver may be part of multiple transmission / reception points.

Hereinafter, a situation in which a signal is transmitted and received through a channel such as PRACH, PUCCH, PUSCH, PDCCH, EPDCCH, and PDSCH may be expressed in the form of 'transmit and receive PRACH, PUCCH, PUSCH, PDCCH, EPDCCH and PDSCH'.

In addition, hereinafter, a description of transmitting or receiving a PDCCH or transmitting or receiving a signal through a PDCCH may be used to mean transmitting or receiving an EPDCCH or transmitting or receiving a signal through an EPDCCH.

That is, the physical downlink control channel described below may mean PDCCH or EPDCCH, and may also be used to include both PDCCH and EPDCCH.

In addition, for convenience of description, the EPDCCH, which is an embodiment of the present invention, may be applied to the portion described as the PDCCH, and the EPDCCH may be applied to the portion described as the EPDCCH as an embodiment of the present invention.

Meanwhile, high layer signaling described below includes RRC signaling for transmitting RRC information including a Radio Resource Control (RRC) parameter.

The eNB performs downlink transmission to the terminals. The eNB includes downlink control information and an uplink data channel (eg, a physical downlink shared channel (PDSCH), which is a primary physical channel for unicast transmission, and scheduling required to receive the PDSCH. For example, a physical downlink control channel (PDCCH) for transmitting scheduling grant information for transmission on a physical uplink shared channel (PUSCH) may be transmitted. Hereinafter, the transmission and reception of signals through each channel will be described in the form of transmission and reception of the corresponding channel.

In the present specification, a terminal may mean a remote station or a remote node, and a base station may mean a host station or a host node. In the following description, a host node represents a node transmitting a signal through a forward link (downlink), and a remote node represents a node transmitting a signal through a reverse link (uplink). In addition, the downlink channel and the uplink channel described below may mean a frequency band of each link channel. That is, the frequency band in which the base station is configured to transmit a signal or a message to the terminal in the FDD mode is described as a downlink or a downlink channel or a frequency band of the downlink channel. Similarly, in the FDD mode, a frequency band in which a terminal is configured to transmit a signal or a message to a base station is described as an uplink or an uplink channel or a frequency band of an uplink channel.

The present invention relates to a random access channel transmission technology in a mobile communication system, and can be applied to all mobile communication systems and communication terminals in a frequency division duplex (FDD) scheme. The present invention is also widely applicable to a mobile communication system using frequency division duplex. First of all, it is possible to reduce the transmission power required for the reverse random access channel in the mobile communication field. In addition, it can be used to extend the coverage radius of the terminal having the same maximum transmission power or limited average transmission power. In addition, the present invention is all communication systems, terminals that need to minimize the power required for communication, such as communication between the sensor network, wireless LAN, machine-to-machine communication (MTC) and medical equipment Applicable to

In particular, it can be usefully used for disaster communication, which has received much attention recently. In the event of a disaster, the transmission power of the terminal is limited so that communication with the base station is often impossible. When the transmission power of the terminal is limited, the random access channel is transmitted when the channel is in a good condition, so that communication is possible even in a situation where communication with the base station is impossible by the conventional technology.

The present invention can be applied to various mobile communication systems such as W-CDMA of 3GPP, LTE, LTE-A, or cdma2000 of 3GPP2. Hereinafter, a description will be given of W-CDMA and LTE systems among the aforementioned mobile communication systems, but the same may be applied to cdma2000.

In FIG. 1, random access channel transmission will be described based on a W-CDMA system as an example of a mobile communication system. The terminal transmits a signal through a random access channel as shown in FIG. 2 is a diagram exemplarily illustrating a configuration of an access probe.

Referring to FIG. 1, it is assumed that a forward channel (downlink) is an access preamble acquisition indication channel (AP-AICH) 130, and that a reverse channel (uplink) is a random access channel (RACH). do. As shown, the terminal transmits the preamble on a random access channel of the reverse link (uplink) for the initial synchronization of the communication. In this case, the terminal transmits an access probe (AP) 0 (100) including a preamble through a random access channel. For example, the terminal transmits an access probe configured as a preamble as shown in FIG. 2A through a random access channel.

If the terminal does not receive a response signal for the AP 0 (100) from the base station during the Tp-p (102) time, the AP 1 (110) that increases the transmission power by ΔP 104 than the AP 0 (100) random Retransmit through the access channel. In this case, the AP 1 110 includes a preamble configured with the same signature as the AP 0 100.

When the base station receives the AP 1 (110) through a random access channel, after waiting for Tpai 120 time and transmits the same signature as the AP 1 (110) to the base station through the AICH (130). Although not shown, the terminal demodulates the signal provided through the AICH 130 to identify the signature and the Acquisition Indicator (AI). If the acknowledgment (ACK) of the base station is confirmed through the acquisition confirmer, the terminal waits for Tp-mag time and then transmits a message including reverse (uplink) data to the base station through a reverse (uplink) random access channel. send. For example, the terminal transmits an access probe including a message configured as shown in FIG. 2B through a random access channel. At this time, the terminal transmits the access probe at a transmission power corresponding to the AP 1 (110). In fact, in W-CDMA, when a terminal receives a message of ACK through AICH, the terminal transmits a random access message. The length of the message is typically 10ms.

In the CDMA2000 random access channel of 3GPP2, the UE transmits an access probe including the message of FIG. 2 (B), and if the UE successfully receives it, it notifies the UE of reception through a forward (downlink) common channel. That is, the AICH is not transmitted and this signal is transmitted as a message on the forward (downlink) common channel.

In case of LTE or LTE-A of 3GPP, the random access channel is transmitted through an uplink channel, and the base station receives the random access channel and transmits a random access response thereto to the terminal through the downlink channel. Random access procedure similar to the above is performed in the FDD-based LTE system. However, the difference from random access channel transmission in W-CDMA is that, after receiving an access probe, the base station allocates resources of the reverse channel through the downlink PDCCH instead of allowing access message transmission through the AICH. Another difference between W-CDMA and LTE is that, after receiving the resource allocation or message transmission of the base station, the LTE system transmits the message in the reverse direction through the PUSCH. The length of a PUSCH is generally in units of 1 ms.

Hereinafter, in order to comprehensively describe each mobile communication system, the above-described reverse link is described as a downlink in which a base station transmits signals and data to a terminal. In addition, the forward link is described as an uplink in which a terminal transmits signals and data to a base station.

3 is a diagram illustrating a pilot channel transmitted in cdma2000 or W-CDMA.

Referring to FIG. 3, the pilot channel exists as one code channel and is always transmitted continuously. The terminal can determine the state of the downlink channel by measuring the pilot channel. When transmitting a random access channel of a conventional cdma2000 or W-CDMA system, a random access channel is transmitted as soon as an event that triggers the random access channel occurs in a higher layer. However, the state of the downlink channel was measured to determine the transmit power during random access channel transmission. In this case, the pilot channel transmitted in the downlink is continuously measured and used to determine the transmission power of the random access channel.

4 illustrates an uplink channel and a downlink channel in an LTE system.

Referring to FIG. 4, in the FDD mode of the LTE and LTE-A systems, an uplink and a downlink channel are physically divided according to frequency bands. In this case, a frequency band for another use may be configured between the uplink channel and the downlink channel.

FIG. 5 is a diagram illustrating an operation process of a terminal and a base station in a contention-based random access procedure in an LTE system.

(1) Send the first message (Msg1)

First, a terminal randomly selects one random access preamble from a set of random access preambles indicated by system information or a handover command, and transmits the random access preamble (PACH). The resource may be selected and transmitted (S501).

(2) Receive the second message (Msg2)

After transmitting the random access preamble as in step S501, the terminal attempts to receive its random access response within the random access response receiving window indicated by the system information or the handover command (S502). In more detail, the random access response information may be transmitted in the form of a MAC PDU, and the MAC PDU may be transmitted through a physical downlink shared channel (PDSCH). In addition, in order for the UE to properly receive the information delivered to the PDSCH, it is preferable that the UE monitors a physical downlink control channel (PDCCH). That is, the PDCCH preferably includes information of a terminal that should receive the PDSCH, frequency and time information of radio resources of the PDSCH, a transmission format of the PDSCH, and the like. Once the UE succeeds in receiving the PDCCH transmitted to the UE, it can properly receive the random access response transmitted to the PDSCH according to the information of the PDCCH. The random access response includes a random access preamble identifier (ID; for example, a RAPID (Random Access Preamble IDentifier)), an uplink grant indicating an uplink radio resource, a UL grant, and a temporary C-RNTI. (Cell-Radio Network Temporary Identifier)) and Timing Advance Command (TAC).

As described above, the reason why the random access preamble identifier is needed in the random access response is that the UL grant and the temporary cell identifier since the random access response information for one or more terminals may be included in one random access response. This is because it is necessary to inform which UE the TAC is valid. In this step, it is assumed that the UE selects a random access preamble identifier that matches the random access preamble selected by the UE in step S502.

(3) Send the third message (Msg3)

When the terminal receives a random access response valid to the terminal, it processes each of the information included in the random access response. That is, the terminal applies the TAC and stores the temporary cell identifier. In addition, the data to be transmitted may be stored in the message 3 buffer in response to receiving a valid random access response.

Meanwhile, the terminal transmits data (that is, a third message) to the base station by using the received UL grant (S503). The third message should include the identifier of the terminal. In the contention-based random access procedure, the base station cannot determine which UE performs the random access procedure, since the UE needs to be identified for future collision resolution.

There are two methods for including the identifier of the terminal. In the first method, if the UE already has a valid cell identifier assigned to the cell before the random access procedure, the UE transmits its cell identifier through an uplink transmission signal corresponding to the UL grant. On the other hand, if a valid cell identifier has not been assigned before the random access procedure, the terminal includes its own unique identifier (eg, S-TSI or Mobile Random Subscriber Identity (S-TMSI) or Random ID). To transmit. In general, the unique identifier is longer than the cell identifier. If the UE transmits data corresponding to the UL grant, it starts a timer for contention resolution (hereinafter referred to as "CR timer").

(4) Receive the fourth message (Msg4)

After the terminal transmits data including its identifier through the UL grant included in the random access response, the terminal waits for instructions from the base station to resolve the collision. That is, an attempt is made to receive a PDCCH in order to receive a specific message (S504). There are two methods for receiving the PDCCH. As mentioned above, when its identifier included in the third message transmitted in response to the UL grant is a cell identifier, it attempts to receive a PDCCH using its cell identifier, and when the identifier is a unique identifier. Attempt to receive a PDCCH using a temporary cell identifier included in the random access response. Then, in the former case, if the PDCCH is received through its cell identifier before the conflict resolution timer expires, the terminal determines that the random access procedure has been normally performed, and terminates the random access procedure. In the latter case, if the PDCCH is received through the temporary cell identifier before the conflict resolution timer expires, the data transmitted by the PDSCH indicated by the PDCCH is checked. If the unique identifier is included in the content of the data, the terminal determines that the random access procedure has been normally performed, and terminates the random access procedure.

FIG. 6 is a diagram illustrating an operation process of a terminal and a base station in a contention-free random access procedure in an LTE system.

Unlike the competition-based random access procedure illustrated in FIG. 5, the operation in the non-competitive random access procedure ends the random access procedure only by transmitting the first message and transmitting the second message. However, before the terminal transmits the random access preamble to the base station as the first message, the terminal is allocated a random access preamble from the base station, and transmits the allocated random access preamble to the base station as a first message, and sends a random access response from the base station. By receiving the random access procedure is terminated.

The non-competition based random access procedure may be performed in the case of a handover procedure or when requested by a command of a base station. Of course, the contention-based random access procedure may be performed in both cases.

(1) Random Access Preamble Allocation

For the non-competition based random access procedure, a dedicated random access preamble having no possibility of collision is allocated from the base station (S601). The random access preamble may be indicated from the base station through the handover command or the PDCCH command.

(2) The terminal transmits the allocated dedicated random access preamble as a first message to the base station (S602).

(3) The method of receiving random access response information (S603) is the same as in the contention-based random access procedure.

In a conventional channel adaptive random access channel transmission scheme, a remote node (eg, a terminal) may be configured to determine a random access channel transmission approach in advance. For example, the remote node measures the forward channel (e.g., downlink channel) and transmits a random access channel only if the forward channel satisfies the transmission condition (e.g., when the channel state is above a preset value). Otherwise, the transmission of the random access channel may be delayed. Therefore, by allowing the transmission of the random access channel only when the state of the channel is good, the transmission power for the transmission of the random access channel can be greatly reduced.

In the channel adaptive random access channel transmission, the remote node can measure the channel state of the TDD forward link and estimate the channel state of the reverse link (eg, uplink) based on the channel reciprocity of the communication method. have.

In this case, the channel gain of the radio channel between the host station (e.g., base station) and the remote station can be used as a reference for measuring the channel state. In the fading channel, since the channel gain of the wireless channel changes with time, the transmission power required for the transmission of the random access channel can be greatly reduced by transmitting the random access channel at the time of high channel gain.

However, in the transmission of the channel adaptive random access channel, the time delay required for the successful transmission of the random access channel may increase. In particular, this may render the use of services requiring low time delays impossible. On the other hand, when the threshold for transmitting random access is lowered to reduce time delay, the performance of the random access channel may be degraded.

In the following embodiments, the remote station allocates a plurality of resources capable of transmitting a random access channel to the reverse link transmitted in the reverse direction, and the remote station selects one of the plurality of resources to create a random access channel send. Random access channel transmission can be improved by using the frequency selectivity of the channel.

<실시예1-1>Example 1-1

In the embodiment of FIG. 7, a plurality of random access transmission resources (eg, 701, 702, and 703) for random access transmission of a terminal are allocated on the uplink resource. In FIG. 7, a communication link is time-divided into a downlink for transmitting a signal to a terminal by a base station and an uplink for transmitting a signal to a base station according to time division. The terminal measures the channel state of the downlink based on the signal received through the downlink. In this embodiment, it may be assumed that a pilot signal such as a reference signal is transmitted over the entire downlink band as in the LTE system.

The terminal may transmit the random access to the base station by using the

resources

701, 702 and / or 703 for random access transmission allocated to the uplink. For example, resources for random access transmission may be allocated on different frequency resources in the same time zone. In the embodiment of Fig. 7, three random

access transmission resources

701, 702 and 703 are set in the same time zone. In addition, the terminal may select one of the allocated resources and transmit a random access.

The UE measures the downlink channel state by measuring a downlink signal (for example, a reference signal), and may transmit a random access when the channel state is good. In this embodiment, the channel state may be measured as a value proportional to the channel gain of the downlink. The terminal may transmit a random access by selecting a resource having a good channel state among resources for transmitting a random access allocated to the uplink. For example, the UE can measure the channel state of each resource for random access transmission on the uplink by measuring the channel state of the downlink channel. In addition, based on the measurement result, the terminal may select a resource for one random access transmission.

In addition, when the channel state of the selected resource satisfies the predetermined random access transmission condition, the terminal may transmit the random access to the base station using the selected resource. In addition, when the channel state of the selected resource does not satisfy the predetermined random access transmission condition, the terminal may delay the transmission of the random access. For example, the random access transmission condition may be that the channel gain of the downlink is more than the threshold.

As described above, in this embodiment, the channel gain of the band corresponding to the resource allocated for random access transmission, rather than the channel gain of the downlink full band, is used to determine whether to access random access. Therefore, instead of the channel gain of the downlink full band, the channel gain of the band corresponding to the resource allocated for random access transmission can be calculated.

For example, if the random access transmission condition is a channel gain of 0 or more (for example, random access transmission in all channel states), when a command indicating the transmission of the random access in the upper layer occurs, the terminal is always random Send access. In this case, the terminal may transmit a random access by selecting a band having the best channel state through the channel state measurement of the downlink channel. In this case, the performance of random access can be improved by using a resource having the highest channel gain according to frequency selectivity among a plurality of random access transmission resources.

In addition, in downlink channel measurement, a pilot signal of a type other than the downlink reference signal may be used. In addition, a signal such as a paging message or a beacon frame of WiFi may be used for channel measurement.

<실시예 1-2><Example 1-2>

In the embodiment of FIG. 7, a plurality of random

access transmission resources

801, 802, and 803 are allocated at the same time of uplink. However, when a plurality of random

access transmission resources

801, 802, and 803 are allocated at the same time, the amount of user data that can be transmitted in the uplink can be reduced instantaneously. In the embodiment of Fig. 8, in order to prevent such a temporary decrease in the amount of user data transmission, a plurality of random

access transmission resources

801, 802, and 803 are allocated on different times. Referring to FIG. 8, similar to the embodiment of FIG. 7, a plurality of random access transmission resources (eg, 801, 802, and 803) are allocated to an uplink channel. However, random

access transmission resources

801, 802, and 803 are allocated at different times.

In FIG. 8, the terminal measures the state of a downlink channel for each random

access transmission resource

801, 802, and 803, and based on this, may determine whether to randomly transmit and select a random access transmission resource. . If the UE decides to transmit the random access, the UE may transmit the random access using the resource having the best channel state among the random

access transmission resources

801, 802, and 803. On the other hand, if it is determined that the random access is not to be transmitted, the terminal may delay the transmission of the random access and continue performing channel measurement. For example, the terminal may continuously perform channel measurement until the predetermined random access transmission condition is satisfied.

Determination of random access transmission and selection of random access transmission resources described above with reference to FIGS. 7 and 8 may be commonly applied to embodiments described later.

<실시예 2><Example 2>

Unlike the TDD communication system described above with reference to FIGS. 7 and 8, in the FDD communication system, downlink and uplink are frequency-divided, and uplink and downlink are separated by relatively large frequency intervals. channel reciprocity) does not apply well.

Therefore, in this embodiment of the FDD communication system, transmission of random access of the terminal may be allowed on some downlink time intervals. That is, the terminal may be configured to measure the downlink channel state by using the signal transmitted in the downlink, and transmit a random access using downlink resources of the same frequency band. Since channel measurement and random access transmission are performed on the same frequency band in the FDD communication system, channel interoperability can be satisfied.

Unlike Embodiment 2 described above, in the following embodiments, the base station transmits a signal for channel measurement through the uplink, the terminal may measure the state of the channel used as the uplink. In this case, a conventional reference signal or a separately designed pilot signal may be used for channel measurement.

In the embodiments to be described below with reference to FIGS. 9A to 9C, a method of transmitting a signal for uplink channel measurement by a base station during a portion of an FDD communication system will be described. For example, the terminal does not transmit a signal through the uplink for a predetermined time period, but instead the base station transmits a signal for uplink channel measurement to the terminal, the terminal may perform the channel measurement for random access transmission. .

<실시예 3-1><Example 3-1>

In FIG. 9A, the base station may transmit a broadband pilot signal 911 for channel measurement. When the wideband pilot signal 911 is transmitted, the UE can calculate the average gain of the wideband channel using the wideband pilot signal 911 as well as for the random

access transmission resources

901, 902, and 903. Narrowband channel gain can also be calculated. In addition, the terminal may determine whether to transmit random access based on the calculated wideband channel gain and / or narrowband channel gain, and may select the random access transmission resource based on the calculated narrowband channel gain.

<실시예 3-2><Example 3-2>

In FIG. 9B, the base station transmits narrowband pilot signals 921, 922, 923 corresponding to the random

access transmission resources

901, 902, 903 for channel measurement. The base station may calculate narrowband channel gain of the corresponding random

access transmission resources

901, 902, 903 using the narrowband pilot signals 921, 922, 923. In addition, the terminal may determine whether to transmit random access based on the calculated narrowband channel gain, and may select the random access transmission resource based on the calculated narrowband channel gain.

<실시예 3-3><Example 3-3>

In the embodiments of FIGS. 9A and 9B, accurate channel measurement may be difficult due to insufficient transmission power of the base station. Thus, in the embodiment of FIG. 9C, each narrowband pilot signals 921, 922, 923 may be transmitted on different time resources to increase channel measurement accuracy. When the narrowband pilot signals 921, 922, 923 are transmitted with different time resources, more accurate channel measurement can be performed because the signal can be transmitted at higher power. In addition, the terminal may determine whether to transmit random access based on the calculated narrowband channel gain, and may select the random access transmission resource based on the calculated narrowband channel gain.

In the following embodiments, a pilot signal for channel measurement when a base station uses two or more antennas will be described. In downlink of the LTE system, different reference signals are transmitted for each antenna, and the terminal performs channel estimation for each antenna. As described above, in the following embodiments, the base station may transmit a pilot signal on the uplink for some time in the FDD communication system. If two or more antennas are used, the terminal needs to measure the channel gain from each antenna and estimate the final channel condition based on all of the measured channel gains (eg, sum the channel gains). . In the following embodiments, it is assumed that the base station has two antennas for convenience of description, but a person skilled in the art can understand that the following embodiments may be applied even when the base station uses three or more antennas. There will be.

<실시예 4><Example 4>

In FIG. 10, a base station transmits pilot signals 1021 for channel measurement simultaneously through two antennas. In addition, a plurality of random access transmission resources (1001, 1002, 1003) are allocated. In this case, signals (eg, pilot signals) for channel measurement from two antennas may be separated from each other using a method such as code division multiplex (CDM) and / or frequency division multiplex (FDM). Although only an embodiment corresponding to the wideband pilot of FIG. 9A is illustrated in FIG. 10, the same method as the pilot signals of FIGS. 9B and 9C may be applied to the present embodiment. When pilot signals are simultaneously transmitted through two antennas as in the embodiment of FIG. 10, resources allocated for pilot signals may be more efficiently utilized.

However, if the pilot signal for channel measurement is simultaneously transmitted through two antennas, two amplifiers may be required for each pilot signal transmission. Therefore, in the following embodiments, the pilot signals may be time-divided and transmitted at different times. That is, since the pilot signal for channel measurement transmitted from each antenna is transmitted at different times, the channel measurement pilot signal for the plurality of antennas may be transmitted using only one amplifier.

11A, 11B, and 11C below correspond to the embodiments of FIGS. 9A, 9B, and 9C described above, respectively, and the same descriptions are omitted for convenience of description. In FIGS. 11A-11C, three random

access transmission resources

1101, 1102, 1103 are set for illustrative purposes.

<실시예 5-1><Example 5-1>

In FIG. 11A, the broadband pilot signal 1111 for antenna 1 and the broadband pilot signal 1121 for antenna 2 are transmitted on different time resources.

<실시예 5-2><Example 5-2>

FIG. 11B shows an example of random access channel transmission for a base station having two antennas according to the embodiment 5-2. FIG.

In FIG. 11B,

narrowband pilot signals

1131, 1132 and 1133 for antenna 1 and

narrowband pilot signals

1141, 1142 and 1143 for antenna 2 are transmitted on different time resources for each antenna.

<실시예 5-3><Example 5-3>

In FIG. 11C,

narrowband pilot signals

1131, 1132, and 1133 for antenna 1 and

narrowband pilot signals

1141, 1142, and 1143 for antenna 2 are transmitted on different time resources for each narrowband pilot signal. .

When receiving a channel measurement signal (for example, a pilot signal) from the plurality of antennas, the terminal may calculate channel gains for each antenna separately. In addition, the terminal may determine whether to transmit a random access (channel) based on the sum of the calculated respective channel gains. In addition, the terminal may select a random access transmission resource.

In the above embodiments, by allocating a plurality of uplink resources for random access transmission, and also by using a plurality of antennas of the base station, the performance of random access is improved and the time delay that occurs in the channel adaptive random access is reduced. Can be reduced.

In the above embodiments, the information about the channel measurement and random access transmission resources may be shared between the terminal and the base station. For example, in which mode the system operates (e.g., whether the base station supports pilot signal transmission using uplink resources) is transmitted to the terminals via broadcasting (e.g., as system information). Can be. In addition, related parameters of operations related thereto (eg, a transmission time, a period, a length, and / or a band, etc. of the pilot signal) may be shared to the terminal through broadcasting.

Hereinafter, a configuration of each of a terminal and a base station capable of performing all the above-described random access channel transmission / reception methods of the present invention will be described with reference to the accompanying drawings.

A terminal 1200 transmitting a random access channel in a frequency division duplex (FDD) mode according to another embodiment of the present invention receives a reference signal for measuring a quality of a transport channel transmitting a random access channel through a transport channel. A receiver 1230 and a control unit 1210 for measuring the quality of the transmission channel using the reference signal, and determines whether the random access channel transmission and a transmission unit 1220 for transmitting the random access channel through the transmission channel.

Referring to FIG. 12, the terminal 1200 includes a receiver 1230, a controller 1210, and a transmitter 1220.

The receiver 1230 receives control information, data, and a message from a base station through a corresponding channel. In addition, the aforementioned reference signal can be received. The reference signal may be received through a transmission channel of a random access channel. That is, according to the above-described embodiments, it may be received through a downlink channel or may be received through an uplink channel. In addition, the receiver 1230 may receive a transmission parameter through a broadcast channel. As described above, the transmission parameter may include one or more information of transmission section information, transmission resource information, and period information of the transmission section capable of transmitting a random access channel in the downlink channel. In addition, the receiver 1230 may receive information about a transmission mode including general mode or disaster mode related information from the base station.

The controller 1210 controls the overall operation of the terminal according to the control of the transmission of the channel-adaptive random access channel required to carry out the above-described present invention. In addition, the controller 1210 may measure the quality of the transmission channel using the reference signal and determine whether to transmit a random access channel. In addition, the controller 1210 may change and control the setting of the transmission mode.

The transmitter 1220 transmits control information, data, and messages to the base station through the corresponding channel. In addition, the transmitter 1220 may transmit a random access channel to the base station through the corresponding transmission channel. The transport channel may be a downlink channel and may be an uplink channel. It may be set differently according to each of the above-described embodiments.

As shown in FIG. 13, the terminal includes an antenna 1300, a receiver 1310, a channel measurer 1320, a reception frequency oscillator 1330, a controller 1340, a transmitter 1350, and a transmission frequency oscillator 1360. It may be configured to include. The antenna 1300 performs a role of receiving a signal transmitted through a wireless channel and transmitting a signal transmitted by a terminal.

The receiver 1310 recovers data from the signal provided from the antenna 1300. For example, the receiver 1310 may be configured to include an RF receiving block, a demodulation block, a channel decoding block, and the like. The RF receiving block is composed of a filter and an RF preprocessor. The channel decoding block includes a demodulator, a deinterleaver and a channel decoder.

The channel measurer 1320 estimates a transmission channel using the received signal provided from the receiver 1310. For example, the channel measurer 1320 estimates the received power of the received signal using the pilot or reference signal of the downlink signal. The receive frequency oscillator 1330 generates a frequency for receiving a signal at the receiver 1310. In general, the reception frequency and the transmission frequency are set differently in the FDD mode.

The controller 1340 determines whether to transmit a random access channel based on the state information of the transmission channel provided from the channel measurer 1320. That is, the controller 1340 compares the power of the received signal estimated by the channel measurer 1320 with a reference value and determines whether to transmit a random access channel. For example, when the power of the received reference signal estimated by the channel measurer 1320 is less than or equal to the reference value, the controller 1340 determines that the transmission channel state is not suitable for random access channel transmission. Accordingly, the controller 1340 controls the transmitter 1350 not to transmit the random access channel. For another example, when the power of the reference signal estimated by the channel measurer 1320 is greater than the reference value, the controller 1340 determines that the transmission channel state is suitable for random access channel transmission. Accordingly, the controller 1340 controls the transmitter 1350 to transmit the random access channel. At this time, the controller 1340 may determine whether to transmit a random access channel using a reference value provided from the base station. For another example, the controller 1340 may calculate a reference value in consideration of a quality of service (QoS) of a service requested by a user.

In the present invention, the controller 1340 may control the terminal to measure the channel state of the transport channel only at a predetermined time. That is, the controller 1340 determines the next transmission channel state measurement time and performs measurement of the transmission channel if the current time is that time. Otherwise, the controller 1340 turns off the terminal until the next measurement time to minimize power consumption. When the next measurement time is reached while the power of the terminal is turned off, the controller 1340 may operate the receiver of the terminal to measure the channel state of the transmission channel.

The transmitter 1350 generates a signal to be transmitted to the base station through a random access channel under the control of the controller 1340. That is, the transmitter 1350 converts a signal to be transmitted to a base station through a random access channel into a form for transmission through a radio resource and provides it to the antenna 1300 only when the controller 1340 controls to perform random access channel transmission. do. For example, the transmitter 1350 includes a signal generation block, a channel code block, a modulation block, an RF transmission block, and the like. The channel code block is composed of a modulator, an interleaver, a channel encoder, and the like. The RF transmission block is composed of a filter and an RF preprocessor.

The transmission frequency oscillator 1360 oscillates a transmission frequency necessary for signal transmission in the transmitter 1350 under the control of the controller 1340.

In the embodiment using the downlink resources as in the second embodiment, the UE instantaneously sets the frequency of the transmitter to the frequency of the receiver and transmits a random access channel using the downlink radio resources in the FDD mode. To this end, the controller 1340 oscillates the frequency of the transmission frequency oscillator 1360 according to the downlink reception frequency.

On the other hand, in the embodiments 3-1 to 5-3, the terminal instantly receives the pilot channel transmitted by the base station using the uplink resources of the FDD mode. To this end, the controller 1340 oscillates the frequency of the reception frequency oscillator 1330 according to the uplink transmission frequency.

The base station 1400 receiving a random access channel from a terminal in a frequency division duplex (FDD) mode according to another embodiment of the present invention generates a reference signal for measuring a quality of a transmission channel through which the terminal transmits a random access channel. The control unit 1410 includes a transmitter 1420 for transmitting a reference signal through a transport channel and a receiver 1430 for receiving a random access channel through a transport channel.

Referring to FIG. 14, the base station 1400 according to another embodiment of the present invention includes a controller 1410, a transmitter 1420, and a receiver 1430.

The receiver 1430 receives data and a message from a terminal through a corresponding channel. In addition, the receiver 1430 may receive the above-described random access channel. That is, the receiver 1430 may transmit a random access channel through the corresponding transmission channel from the terminal. The transport channel may be a downlink channel and may be an uplink channel. It may be set differently according to each of the above-described embodiments.

The controller 1410 may generate a reference signal for quality measurement of a transmission channel through which the terminal transmits a random access channel. In addition, the controller 1410 controls the overall operation of the base station according to receiving the channel-adaptive random access channel required to carry out the above-described present invention. In addition, the controller 1410 may generate a signal for setting a transmission mode, and generate a transmission parameter and a reference signal parameter.

The transmitter 1420 may transmit a reference signal through a transmission channel. The reference signal may be transmitted through a transmission channel of a random access channel. That is, according to the above-described embodiments, it may be transmitted through a downlink channel or through an uplink channel. In addition, the transmitter 1420 may transmit a transmission parameter through a broadcast channel. As described above, the transmission parameter may include one or more information of transmission section information, transmission resource information, and period information of the transmission section capable of transmitting a random access channel in the downlink channel. In addition, the transmitter 1420 may transmit information about a transmission mode including general mode or disaster mode related information to the terminal.

In addition, the transmitter 1420 transmits control information, data, and messages to the terminal through a corresponding channel.

The structure of the base station 1400 may be similar to that of the terminal of FIG. 13. For example, the transmitter 1420 may include a transmission frequency oscillator, and the receiver 1430 may include a reception frequency oscillator. In the embodiment using the downlink resources as in the second embodiment, the base station 1400 sets the frequency of the receiver 1430 to be the same as the downlink frequency to receive a random access channel using the downlink radio resources in the FDD mode can do. To this end, the controller 1410 may control the frequency of the reception frequency oscillator to oscillate according to the frequency of the downlink. In addition, in the embodiment using uplink resources as in the embodiments 3-1 to 5-3, the base station 1400 sets the frequency of the transmitter 1420 to be the same as the uplink frequency to uplink radio resources in the FDD mode Can transmit a pilot channel. To this end, the controller 1410 may control the oscillator to oscillate according to the frequency of the uplink frequency.

15A is a schematic diagram of a base station operating in a TDD mode according to an example. Since the structure of the base station 1500a is the same as that described above with reference to FIG. 14, duplicate description thereof will be omitted.

15B is a schematic diagram of a base station operating in an FDD mode according to another example. The base station 1500b may further include a separate transmitter 1530b for pilot signal transmission on the uplink. In addition, the base station 1500b may further include a duplexer 1540b.

16A is a schematic diagram of a base station operating in an FDD mode according to an example. The base station 1600a includes two

antennas

1640a and 1645a, and thus includes

ADCs

1620a and 1625a and

power amplifiers

1630a and 1635a corresponding to each antenna.

16B is a schematic diagram of a base station operating in an FDD mode according to another example. The base station 1600b transmits pilot signals for one of the two antennas 1650b and 1655b using one power amplifier 1630b. Each pilot signal may be time-divided using the switch 1640b. Therefore, since one power amplifier 1630b and ADC 1620b are used, the implementation cost of the base station 1600b can be reduced.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

CROSS-REFERENCE TO RELATED APPLICATIONCROSS-REFERENCE TO RELATED APPLICATION

This patent application is related to the patent application No. 10-2015-0019564 filed in Korea on Feb. 09, 2015 and the patent application No. 10-2016-0014592 filed in Korea on Feb. 05, 2016. Priority is claimed under section (a) (35 USC § 119 (a)), all of which is incorporated by reference in this patent application. In addition, if this patent application claims priority for the same reason for countries other than the United States, all its contents are incorporated into this patent application by reference.

Claims

A random access channel transmission method of a terminal in a wireless communication system,

Receiving one or more pilot signals for measurement of channel conditions from a base station;

A channel state is measured based on the one or more pilot signals, and one transmission resource is selected from among a plurality of transmission resources allocated for transmission of the random access channel and transmission of the random access channel based on the measured channel state. Determining; And

And if the transmission of the random access channel is determined, transmitting the random access channel to the base station using the determined one transmission resource.
The method of claim 1,

The determined one transmission resource is a transmission resource having the highest channel gain among the plurality of transmission resources among the plurality of transmission resources, random access channel transmission method.
The method of claim 1,

The wireless communication system is a time division duplex (TDD) wireless communication system, the one or more pilot signals are received to the terminal through the downlink, the random access channel is transmitted to the base station through the uplink, random access Channel transmission method.
The method of claim 3, wherein

And the plurality of transmission resources are allocated on different frequency resources.
The method of claim 3, wherein

And the plurality of transmission resources are allocated on different time resources.
The method of claim 1,

The wireless communication system is a frequency division duplex (FDD) wireless communication system, the one or more pilot signals are received by the terminal through the resources set in the downlink, the plurality of transmission resources are resources set in the downlink Random access channel transmission method assigned on the network.
The method of claim 1,

The wireless communication system is a frequency division duplex (FDD) wireless communication system, the at least one pilot signal is received by the terminal through a resource configured in the uplink, each of the plurality of transmission resources is configured in the uplink A random access channel transmission method, allocated on different frequency resources on resources.
The method of claim 7, wherein

The at least one pilot signal is one broadband pilot signal,

The terminal measures a channel state of narrowband channels corresponding to each of the plurality of transmission resources based on the wideband pilot signal, and based on the channel state of narrowband channels corresponding to each of the plurality of transmission resources. The random access channel transmission method of selecting one transmission resource for the random access channel transmission of a plurality of transmission resources.
The method of claim 7, wherein

And the one or more pilot signals are allocated on frequency resources corresponding to each of the plurality of transmission resources.
The method of claim 9,

And wherein the one or more pilot signals are allocated on different time resources.
The method of claim 7, wherein

And the at least one pilot signal is a plurality of pilot signals corresponding to each of a plurality of antennas of the base station.
The method of claim 11,

The plurality of pilot signals are received on the same time resource, each of the plurality of pilot signals are separated by a Code Division Multiplex (CDM) or Frequency Division Multiplex (FDM) scheme.
The method of claim 11,

Wherein each of the plurality of pilot signals is allocated on different time resources.
The method of claim 11,

Wherein each of the plurality of pilot signals comprises a plurality of narrowband pilot signals corresponding to a frequency band of each of the plurality of transmission resources.
The method of claim 14,

And the plurality of narrowband pilot signals are allocated on different time resources.
A terminal for transmitting a random access channel in a wireless communication system,

A receiver for receiving a signal from a base station;

A transmitter for transmitting a signal to the base station; And

A control unit configured to control the receiving unit and the transmitting unit,

The control unit,

Receive one or more pilot signals for measurement of channel conditions from the base station,

A channel state is measured based on the one or more pilot signals, and one transmission resource is selected from among a plurality of transmission resources allocated for transmission of the random access channel and transmission of the random access channel based on the measured channel state. Decide,

And if the transmission of the random access channel is determined, transmitting the random access channel to the base station using the determined one transmission resource.