KR20130033274A - Method for generating random access signal of machine type communication device using narrow bandwidth - Google Patents

Abstract

Disclosed are a method and a device for generating a random access signal for a narrowband MTC device. The random access signal generation method for a MTC device may include assigning a location in a frequency domain of a random access signal dedicated to the MTC device, that is, a frequency location to transmit a random access preamble to a center location of a base station system bandwidth, or The random access signal may be generated using a method of moving the center frequency of the MTC device to the random access frequency location allocated for the legacy LTE terminal.

Description

A method of generating a random access signal of a narrowband telecommunication device {METHOD FOR GENERATING RANDOM ACCESS SIGNAL OF MACHINE TYPE COMMUNICATION DEVICE USING NARROW BANDWIDTH}

The present invention relates to a method of generating a random access signal, and more particularly, to a method of generating a random access signal of a narrowband MTC device.

Machine type communication or machine to machine communication refers to a form of data communication associated with one or more entities for which human intervention is not necessary.

Services optimized for IoT are different from services optimized for human-to-human communications, including: a) different market scenarios, b) data communications, c) lower cost and effort, and d) a very large number of potential communications. Terminals, e) differ from current mobile network communications in that they relate to characteristics such as very little traffic per terminal, up to a large range.

Things communication can appear in various forms of services, such as Smart Metering, Tracking & Tracing, Remote Maintenance & Control, and eHealth.

Recently, 3GPP is also working on MTC (Machine Type Communication) standardization for intelligent communication between people and things, and things and things. A large number of MTC devices are deployed and operated for various MTC applications whose main functions are smart metering and remote control.

In the 3rd Generation Partnership Project (3GPP) LTE system, both an IoT communication device and a general user are treated as one UE and must be individually registered in the LTE network. The arrangement of the plurality of MTC devices may cause scheduling competition for channel allocation, exhaustion of radio resources, overload due to signal generation, and the like, thus adversely affecting existing general terminals. 3GPP is proceeding standardization with a focus on minimizing the adverse effect of the deployment of the telecommunications device. In addition, efforts are being made to further expand the IoT service through LTE by providing an inexpensive IoT device.

In this regard, all Long Term Evolution (LTE) -based user equipment (User Equipment) is defined in the standard to support the transmission and reception bandwidth up to 20 MHz. Therefore, from the perspective of the IoT device, a legacy LTE user terminal, which is a legacy terminal, may access an eNodeB having a 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, or 20 MHz bandwidth. have. In general, the MTC device or the terminal is characterized by transmitting a very small amount of information. Thus, supporting bandwidths up to 20 MHz, such as general user terminals, can be a significant waste of cost for IoT devices targeting low cost.

As a solution to this problem, discussions have been made to allow the MTC device to operate with a narrow band. That is, even if the base station uses a wide bandwidth, the MTC device only supports narrow bands such as 1.4 MHz and 5 MHz bandwidth. To make this possible, a separate radio transmission standard work is required to support communication between a narrow-band communication device and a base station.

SUMMARY OF THE INVENTION An object of the present invention for overcoming the above problems is to provide a method for generating a random access signal by a narrowband MW device in a 3GPP LTE based mobile communication system supporting a scalable system bandwidth of up to 20 MHz. There is.

The method for generating a random access signal of a narrowband MTC device according to an embodiment of the present invention for achieving the above object of the present invention is a position in the frequency domain of a random access signal dedicated to the MTC device, that is, random access. A random access signal may be generated by allocating a frequency position to transmit the preamble to a center position of the base station system bandwidth.

According to another aspect of the present invention, there is provided a method for generating a random access signal of a MTC device, wherein a center frequency of the MTC device is assigned to a random access frequency location allocated by a base station for a legacy LTE terminal. Move to generate a random access signal.

When the MTC device has a dedicated bandwidth, a method of generating a random access signal of a narrowband MTC device according to another embodiment of the present invention for achieving the above object of the present invention includes: a random access preamble format from an upper layer; Receiving information on a transmission time point and random access using the received random access preamble format and information on the transmission time, and frequency resource block related information for a random access signal fixed according to the bandwidth of the MTC device. Generating a signal.

Here, the dedicated bandwidth of the MTC device may be set to 1.4 MHz, for example.

According to another aspect of the present invention, a narrowband MTC device receives information on a random access preamble format and a transmission time point from an upper layer, and receives the random access preamble format and transmits the received information. The random access signal may be generated using the information about the viewpoint and the frequency resource block related information for the fixed random access signal according to the bandwidth of the MTC device.

By using the random access signal generation method as described above, it is possible to generate a random access signal that allows the 3GPP LTE-based mobile communication system and the narrowband IoT device to support scalable system bandwidth up to 20 MHz. Do.

In addition, when the MTC device has a dedicated bandwidth of 1.4 MHz, the method of generating a random access signal can be simplified.

In addition, it is possible to change the current wireless transmission standard to the wireless transmission standard optimized for MTC only, and to reduce the total number of upper layer parameters by removing unnecessary upper layer parameters.

1 is a conceptual diagram of a wireless communication network providing an MTC service to which the present invention is applied.
2 is a message flow diagram between a terminal and a base station in a random access procedure of the terminal in the 3GPP LTE system.
3 is a conceptual diagram of an embodiment of a random access signal generation method according to a first method of the present invention.
4 is a conceptual diagram of another embodiment of a random access signal generation method according to the first method of the present invention.
5 is a conceptual diagram of an embodiment of a random access signal generation method according to a second method of the present invention.
6 is a conceptual diagram of another embodiment of a random access signal generation method according to a second method of the present invention.
7 is a flowchart of a random access operation in a MTC device according to the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be limiting of the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "have" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

A "terminal" used in the present application includes a mobile station (MS), a user equipment (UE), a user terminal (UT), a wireless terminal, an access terminal (AT), a terminal, a subscriber unit, A subscriber station (SS), a wireless device, a wireless communication device, a wireless transmit / receive unit (WTRU), a mobile node, a mobile, or other terminology. Various embodiments of the terminal may be used in various applications such as cellular telephones, smart phones with wireless communication capabilities, personal digital assistants (PDAs) with wireless communication capabilities, wireless modems, portable computers with wireless communication capabilities, Devices, gaming devices with wireless communication capabilities, music storage and playback appliances with wireless communication capabilities, Internet appliances capable of wireless Internet access and browsing, as well as portable units or terminals incorporating combinations of such functions However, the present invention is not limited thereto.

The term 'base station' used in the present application generally refers to a fixed point for communicating with a terminal, and includes a base station, a node-B, an eNode-B, and a base transceiver system (BTS). Or other terms such as access point.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

1 is a conceptual diagram of a wireless communication network providing an MTC service to which the present invention is applied.

As shown in FIG. 1, a wireless communication network providing an MTC service further includes an MTC server 300, an MTC device 110, an MTC user 400, and the like for providing an MTC service in addition to an existing wireless communication network. do.

The MTC device 110 is a terminal (UE) having an MTC communication function for communicating with the MTC server 300 and other MTC devices through a Public Land Mobile Network (PLMN).

The MTC server 300 communicates with the PLMN and communicates with the MTC device 110 via the PLMN. The MTC server 300 also has an interface accessible by the MTC user and provides a service for the MTC user 400. The MTC user 400 uses a service provided by the MTC server 300.

In the configuration of FIG. 1, the MTC server 300 is controlled by a network operator, the network operator provides an application programming interface (API) on the MTC server, and the MTC user 400 is connected to the MTC server of the network operator through the API. Access.

In FIG. 1, the MTC server is included in the network operator domain. However, the MTC server may be located outside the network operator domain without being located in the network operator domain. In this case, the MTC server is not controlled by the network operator. It does not have a form.

In addition, the MTC device 110 is via a base station (not shown) to communicate with the MTC server 300 and the like located in the network.

2 is a message flow diagram between a terminal and a base station in a random access procedure of the terminal in the 3GPP LTE system.

The random access procedure is a process for accessing the terminal's network and is performed in the case of initial access, handover, scheduling request, and uplink time synchronization acquisition. That is, all terminals perform random access for initial access and data transmission.

The random access procedure illustrated in FIG. 2 refers to a random access signal generation procedure in 3GPP TS 36.211 of the 3GPP LTE-based wireless transmission standard.

When the UE selects the random access preamble, the terminal selects a group to be selected using the information received through the system information, and randomly determines a group to access the base station. That is, in order for the terminal to perform a random access procedure, a procedure (S201) for first receiving system information from the base station is required.

Here, in relation to system information including information on random access preamble selection, in a 3GPP LTE system, a common broadcast channel (broadcast) is transmitted to terminals by including common channel related information and general information about the system in system information at a base station. channel).

Three types of RRC messages are used to convey system information: MIB messages, SIB1 messages, and system information (SI) messages.

System information is organized in the form of system information blocks (SIBs), each system information block comprising a set of functionally related parameters. Here, the system information block is a MIB (Master Information Block) including a limited number of parameters most frequently transmitted as parameters necessary for initial access to the network of the terminal according to the characteristics thereof, and whether the corresponding cell is a cell suitable for cell selection. System information block type 1 (SIB1) including information related to time domain scheduling of other SIBs and system information block type 2 (SIB2) including common and shared channel information. Can be.

After receiving the system information, the UE sets up a channel, analyzes the information on the random access channel to perform an initial random access, and then selects one preamble among possible random access preambles and starts a random access procedure.

In more detail, the UE transmits a preamble format (Preamble format) for transmitting a random access signal from a parameter ( prach - ConfigurationIndex ) related to a physical random access channel (PRACH) configuration index among system information received from a base station. Information is obtained (S203).

) 및 시퀀스 부분의 길이(

)가 정의된다. 또한, 각 PRACH 구성 인덱스에 대해서는 프레임 구조별로 프리엠블 포멧, 10ms 단위에서의 밀도, 버전 등이 정의된다. Here, the preamble format has five types of formats ranging from 0 to 4, and each format is controlled by a higher layer according to a frame structure and a random access configuration. For each format, the cyclic prefix length (

) And the length of the sequence part (

) Is defined. In addition, for each PRACH configuration index, a preamble format, a density in 10 ms units, a version, and the like are defined for each frame structure.

On the other hand, the UE obtains the physical resource block (PRB) number information in the frequency domain for transmitting a random access signal from the parameter ( prach - FrequencyOffset ) of the PRACH frequency offset of the system information received from the base station (S205).

The UE uses the obtained information, that is, a preamble format for transmitting a random access signal, information on a transmission time point, and a PRB number in a frequency domain for transmitting a random access preamble signal. An emblem signal is generated (S207).

Thereafter, the terminal 100 randomly selects the generated random access preamble and transmits the selected preamble to the base station 200 (S209).

The base station 200 receives the preamble transmitted by the terminal 100 and transmits a random access response message to the terminal (S211). If the terminal successfully receives the random access response message for the preamble transmitted by the terminal, the terminal performs scheduled uplink transmission using an uplink radio resource allocated from the base station to establish a radio resource control (RRC) connection. (S213).

In relation to the 3GPP LTE-based radio transmission standard, a base station in a cell allocates a frequency resource of 1.08 MHz corresponding to six Physical Resource Blocks (PRBs) for random access signal reception, and the location of the random access frequency resource. May be allocated to any frequency resource in the entire frequency domain of the base station (eNB) system bandwidth.

Therefore, when the transmission bandwidth of the MTC device is smaller than the reception system bandwidth of the base station, for example, when the bandwidth of the base station system is 20 MHz and the transmission bandwidth of the IoT device is 1.4 MHz, the random access frequency allocated by the base station The location of the resource may be allocated outside the frequency domain used by the telecommunications device. Accordingly, a problem arises in the current standard that the MTC device cannot generate or transmit a random access signal.

Accordingly, the present invention proposes a method for generating a random access signal by a MTC device having a narrower bandwidth than a bandwidth supported by a 3GPP LTE-based mobile communication system supporting a scalable system bandwidth of up to 20 MHz.

In addition, when the MTC device has a narrow bandwidth, for example, 1.4 MHz, the random access signal generation method specified in the 3GPP LTE-based wireless transmission standard is optimized to generate a random access signal for the MTC device. I would like to propose.

According to the 3GPP LTE-based standard, transmission bandwidths of 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, and 20 MHz are available. In addition, the number of PRBs used for each transmission bandwidth is defined as 6 PRBs, 15 PRBs, 25 PRBs, 50 PRBs, 75 PRBs, and 100 PRBs, respectively.

In addition, in the 3GPP LTE-based wireless transmission standard, the random access signal is defined to occupy six PRBs corresponding to 1.4 MHz bandwidth (the actual frequency resource is 1.08 MHz and the guard band on both sides).

Based on this understanding of the 3GPP LTE based mobile communication system, a method for generating a random access signal for a telecommunication device using a narrowband according to the present invention is largely divided into two methods which will be described in detail below. can do.

According to the method of generating a random access signal according to the first method of the present invention, a position in a frequency domain of a random access signal dedicated to an IoT communication device, that is, a frequency position to transmit a random access preamble is assigned to a center position of a base station system bandwidth. do.

The random access signal generation method according to the second method of the present invention is a method of moving the center frequency of the MTC device to a random access frequency location allocated by the base station for the legacy LTE terminal.

Hereinafter, each embodiment will be described in detail with reference to FIGS. 3 to 6.

3 is a conceptual diagram of an embodiment of a random access signal generation method according to a first method of the present invention.

That is, FIG. 3 is a conceptual diagram of an embodiment of allocating a random access frequency resource 2100 dedicated to an MTC device to a center frequency position 201 of an eNB system bandwidth 2000.

In FIG. 3, the MTC terminal (MTC terminal) shows both the case of having a 5 MHz bandwidth (1100-1) and the case of having a 1.4 MHz bandwidth (1100-2). In both cases, as shown in FIG. 3, the center frequency 201 of the base station system bandwidth and the center frequency 101 of the MTC device are matched. In this case, in addition to random access resource allocation such as frequency location and transmission time for the legacy LTE terminal in the cell, random access resource allocation dedicated to the MTC device may be required.

Here, the resources 2100 and the random access signal 1110 allocated for preamble reception occupy resources corresponding to 6 PRBs (1.08 MHz).

4 is a conceptual diagram of another embodiment of a random access signal generation method according to the first method of the present invention.

4 is assuming that the transmission bandwidth of the MTC terminal (MTC terminal) is 5 MHz. Referring to FIG. 4 according to an embodiment of the present invention, in the state where the center frequency 201 of the base station system bandwidth and the center frequency 101 of the MTC device are aligned, the random access frequency resource 1110 for the MTC device. ) Is assigned to a location of another frequency resource that is not centered but within the MTS device transmission bandwidth range.

5 is a conceptual diagram of an embodiment of a random access signal generation method according to a second method of the present invention.

FIG. 5 is a block diagram of an embodiment in which the MTC device moves the center frequency 101 of the MTC device bandwidth from the base station to the location of the random access frequency resource 2100 allocated for the legacy LTE terminal.

In this case, the MTC device may also use random access resources such as frequency location and transmission time allocated for the legacy LTE terminal in the cell. However, this embodiment does not exclude allocating random access resources dedicated to the MTC device.

As in FIG. 5, the MTC device moves its center frequency 101 to the exact center of the random access frequency location 2100 for the legacy LTE terminal allocated within the base station system bandwidth.

6 is a conceptual diagram of another embodiment of a random access signal generation method according to a second method of the present invention.

FIG. 6 is a frequency band of a telecommunication device such that the random access frequency resource 2100 for the legacy LTE terminal is included in the range of the entire frequency band 1100-1 for the MTC device, on the extension of the embodiment shown through FIG. 5. An embodiment of moving and setting 1110 is shown.

In various embodiments of the method for generating a random access signal according to the present invention with reference to FIGS. 3 to 6, the MTC device is described as using a narrow band such as 1.4 MHz and 5 MHz bandwidth, but the present invention is not limited thereto. It will also be possible for a telecommunications device to use a bandwidth other than 1.4 MHz and 5 MHz bandwidth.

In addition, when the transmission bandwidth of the MTC device is equal to or wider than the reception system bandwidth of the base station, the MTC device uses a random access resource such as a frequency location and a transmission time point for the legacy LTE terminal in the cell together with the legacy LTE terminal. A method, or a method of allocating a random access resource dedicated to a MTC device, apart from random access resource allocation for a legacy LTE terminal, will also be included in the scope of the present invention.

In the following, when the MW device has a dedicated bandwidth of 1.4 MHz, the random access signal generation method specified in the conventional 3GPP LTE-based wireless transmission standard is optimized for the MW device using the 1.4 MHz dedicated bandwidth. The random access signal generation method proposed by the present invention will be described.

First, referring to the existing random access signal generation process, the terminal is a physical resource block in the frequency domain for transmitting a random access signal from a parameter ( prach -FrequencyOffset ) on the PRACH frequency offset of the system information received from the base station A) obtaining number information.

However, since the narrowband MTC device considered in the present invention supports a fixed fixed bandwidth, for example, a bandwidth of 1.4 MHz, the PRB number information may be regarded as fixed. That is, in the present invention, a random access signal is generated using a fixed parameter value for the PRB number in the frequency domain without having to receive a parameter related to the PRACH frequency offset.

Furthermore, in the present invention, the equation used for random access signal generation in the 3GPP LTE-based wireless transmission standard is optimized to the equation for supporting the MTC device.

7 is a flowchart illustrating a random access operation in a MTC device according to the present invention.

The UE obtains a preamble format and transmission time information for transmitting a random access signal from an upper layer through reception of a parameter prach - ConfigurationIndex regarding a PRACH configuration index (S701).

Thereafter, the MTC device generates a random access signal by using a fixed parameter value related to the PRB number in the frequency domain and a preamble format for transmitting the random access signal acquired through the upper layer and transmission time information (S703).

Herein, the part requiring the change of the standard according to the method proposed by the present invention will be described in comparison with the conventional method specified in the standard for generating the random access signal as follows.

First, the equation for generating the random access signal defined by the conventional standard is expressed by Equation 1 below.

는 진폭(amplitude) 스케일링 팩터,

는 자도프-추 시퀀스(Zadoff-Chu sequence)의 길이를 나타낸다. 또한,

이다.

는 랜덤 액세스 프리엠블 및 업링크 데이터 전송 간의 간격 차이를 고려한 팩터이다. 또한,

는 서브캐리어 스페이싱을 나타내고, 변수

는 랜덤 액세스 프리엠블에 대한 서브캐리어 스페이싱 (spacing)을 나타내는 값으로 프리엠블 포멧에 따라 정해진 값을 갖는다. 변수

은 PRB 내에서 랜덤 액세스 프리엠블의 주파수-도메인 위치를 결정하는 오프셋 값으로, 프리엠블 포멧에 따라 정해진 값을 갖는다. Where s (t) is a random access signal,

Is the amplitude scaling factor,

Represents the length of the Zadoff-Chu sequence. Also,

to be.

Is a factor that takes into account the gap difference between random access preamble and uplink data transmission. Also,

Represents subcarrier spacing, and the variable

Is a value representing subcarrier spacing for the random access preamble and has a value determined according to the preamble format. variable

Is an offset value that determines the frequency-domain position of the random access preamble in the PRB and has a value determined according to the preamble format.

는 PRACH 자원에 의해 점유되는 첫번째 PRB를 나타내며, 상위 계층으로부터 PRACH 오프셋에 관한 파라미터(prach - FrequencyOffset)의 수신을 통해 얻을 수 있다. here,

Denotes the first PRB occupied by the PRACH resource, and can be obtained through reception of a parameter ( prach - FrequencyOffset ) regarding the PRACH offset from the upper layer.

Next, a random access signal generation method according to the present invention for supporting a MTC device using a dedicated bandwidth of 1.4 MHz will be described with reference to Equation 1 below.

은 상위계층으로부터 별도의 수신 없이 자체적으로 고정 파라미터 값을 갖는다 (예를 들어,

=0). 수학식 1에서

는 고정된 값

으로 변경된다. (예를 들어,

=6).parameter

Has a fixed parameter value of itself without separate reception from a higher layer (e.g.,

= 0). In Equation 1

Is a fixed value

Is changed to (E.g,

= 6).

Accordingly, the random access signal generation method according to the present invention can be summarized as in Equation 2 below.

는 진폭(amplitude) 스케일링 팩터,

는 자도프-추 시퀀스(Zadoff-Chu sequence)의 길이를 나타낸다.

는 랜덤 액세스 프리엠블 및 업링크 데이터 전송 간의 간격 차이를 고려한 팩터이다. 또한,

는 서브캐리어 스페이싱을 나타내고, 변수

는 랜덤 액세스 프리엠블에 대한 서브캐리어 스페이싱 (spacing)을 나타내는 값으로 프리엠블 포멧에 따라 정해진 값을 갖는다. 변수

은 PRB 내에서 랜덤 액세스 프리엠블의 주파수-도메인 위치를 결정하는 오프셋 값으로, 프리엠블 포멧에 따라 정해진 값을 갖는다. Where s (t) is a random access signal,

Is the amplitude scaling factor,

Represents the length of the Zadoff-Chu sequence.

Is a factor that takes into account the gap difference between random access preamble and uplink data transmission. Also,

Represents subcarrier spacing, and the variable

Is a value representing subcarrier spacing for the random access preamble and has a value determined according to the preamble format. variable

Is an offset value that determines the frequency-domain position of the random access preamble in the PRB and has a value determined according to the preamble format.

이며,

는 PRACH 자원에 의해 점유되는 첫번째 PRB를 나타내며, 고정 파라미터 값인

에 의해 결정된다. Also,

Is,

Represents the first PRB occupied by the PRACH resource and is a fixed parameter value

.

값을 구하는 방법으로 다음과 같이 3 가지 바람직한 실시예를 제안한다. Here, in the present invention for each frame structure type

As a method of obtaining a value, three preferred embodiments are proposed as follows.

First, the first PRB occupied by the PRACH resource for the frame structure type 1 (corresponding to FDD) may be defined as in Equation 3 below.

이 고정 값 '0'을 가진다고 할 때, k ₀의 값은 -36이 된다.

here,

Assuming that this fixed value is '0', the value of k ₀ is -36.

Second, the first PRB occupied by the PRACH resources for the preamble formats 0 to 3 of the frame structure type 2 (corresponding to TDD) may be defined as Equation 4 below.

은 상위계층으로부터 받은 값이 아닌 고정 파라미터 값이다.here,

Is a fixed parameter value, not a value received from a higher layer.

Third, the first PRB occupied by the PRACH resource for the preamble format 4 among the frame structure type 2 (corresponding to TDD) may be defined as Equation 5 below.

The MTC device generates a random access preamble using information on the first PRB occupied by the PRACH resource determined according to one of Equations 3 to 5 (S703).

7 again, the MTC device transmits the generated random access preamble to the base station (S705). The MTC device waits to receive a random access response from the base station (S707), and then performs scheduled uplink transmission (S709).

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

100: user terminal
110: MTC terminal (or communication device)
300: MTC Server

Claims (1)

A method for generating a random access signal of a narrowband MTC device,
Receiving information regarding a random access preamble format and a transmission time point from an upper layer; And
Generating a random access signal using information on the received random access preamble format and transmission timing and frequency resource block related information for a random access signal fixed according to a bandwidth of the MTC device; How it happens.

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