KR20160118694A - System and method for transmitting Machine Type Communication data - Google Patents

Abstract

The present invention relates to an MTC data transmission system and method. A system according to the present invention is a system that is synchronized through a backhaul between a base station located in a neighboring macro cell or a small cell and allocates ABS (Almost Blank Subframe) to a subframe of a data signal, And a user terminal for receiving a control signal and a data signal from the base station through a downlink, wherein the user terminal identifies synchronization information of a physical channel included in an ABS allocated to a subframe of the data signal, MTC (Machine Type Communication) data is allocated to an area of an ABS sub-frame to which the physical channel symbol is not allocated, and is transmitted through an uplink through a downlink carrier frequency.

Description

[0001] MTC data transmission system and method [0002]

The present invention relates to a MTC (Machine Type Communication) data transmission system and method.

MTC (Machine Type Communication) technology based on LTE (Long Term Evolution) is a LTE-based Internet technology for objects, and LTE and LTE MTC terminals must be used at the same frequency. At this time, each UE must reuse the existing LTE network, and the MTC UE must transmit data within a wide cell coverage while being inexpensive.

In recent years, in order to solve the interference problem between the base station and the base station according to the increase of the small cell and the multi-RRH (Radio Remote Head), an environment construction method for eliminating ICIC (Inter-Cell Interference Coordination) has been studied.

One of them is a downlink signal of a neighbor base station as a backhaul to achieve symbol synchronization, frequency offset, and radio frame synchronization between a base station and a base station. .

In order to transmit a minimum ICIC to a terminal on a cell boundary, a macro cell BS transmits an ABS (Almost Blank subframe) to a specific subframe, and a channel transmitted in the ABS includes a Primary Synchronization Signals (PSS), a Secondary Synchronization Signals), PBCH (Physical Broadcast Channel), and CRS (Cell Specific Reference Signal). However, since ABS does not allocate resources except PSS, SSS, PBCH, and CRS, there is a large loss in downlink resource utilization of the base station.

Korean Patent Publication No. 10-2014-77011377

An object of the present invention is to allocate a data channel of a MTC terminal capable of half-duplex frequency division to an ABS region which is left empty to control ICIC between base stations, and to transmit MTC uplink data to a downlink frequency band of a base station And a MTC data transmission system for receiving MTC data at a downlink receiving end through a base station backhaul for synchronization between the BSs.

The technical problems of the present invention are not limited to the above-mentioned technical problems, and other technical problems which are not mentioned can be understood by those skilled in the art from the following description.

According to an aspect of the present invention, there is provided an MTC data transmission system, comprising: a base station located in a neighboring macro cell or a small cell and synchronized with a backhaul between cells; And a user terminal for receiving a control signal and a data signal from the base station through a downlink.

Herein, the user terminal checks the synchronization information of the physical channel included in the ABS allocated to the subframe of the data signal, adds MTC (Machine Type Communication) data to the area of the ABS subframe to which the physical channel symbol is not allocated, And transmits the uplink through the downlink carrier frequency.

The ABS includes a Primary Synchronization Signals (PSS), a Secondary Synchronization Signals (SSS), a Physical Broadcast Channel (PBCH), and a Cell Specific Reference Signal (CRS) symbol, which are physical channels related to a concurrent downlink signal .

The user terminal allocates MTC data to a subframe region of the ABS using a downlink 1.4M bandwidth.

The user terminal allocates MTC data to a subframe region of the ABS using a half-duplex FDD scheme.

The user terminal transmits the MTC data on the uplink using a downlink carrier frequency at a timing controlled through an uplink random access channel (RACH).

And the user terminal is an MTC terminal located in a border area of a cell.

According to the present invention, when one base station transmits data in the downlink using multi-RRH, or when there are several small cells in one macrocell base station, inter-cell interference co-ordination (ICIC) It is possible to increase the downlink reception ratio of the terminal in the base station system and increase the data transmission rate to the MTC terminal at the cell boundary in the base station system, thereby widening the cell coverage and minimizing the transmission power of the terminal.

In addition, according to the present invention, there is an advantage that resource utilization is increased because a downlink carrier wave not allocated symbols is used without using additional resources to transmit MTC data.

1 is a block diagram illustrating a configuration of an MTC data transmission system according to an embodiment of the present invention.
2 is a diagram illustrating a configuration of an MTC data transmission system according to another embodiment of the present invention.
3A and 3B are diagrams illustrating a frame structure transmitted from the MTC data transmission system to the MTC terminal according to the present invention.
4A is a diagram illustrating a structure of a downlink ABS subframe in the MTC data transmission system according to the present invention.
FIG. 4B is a diagram illustrating an allocation region for MTC data in a downlink ABS subframe structure according to the present invention.
FIG. 5 is a diagram illustrating an operation of allocating MTC data in an MTC data transmission system according to an embodiment of the present invention. Referring to FIG.
6 is a flowchart illustrating an operation of the MTC data transmission method according to the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. It should be noted that, in adding reference numerals to the constituent elements of the drawings, the same constituent elements are denoted by the same reference symbols as possible even if they are shown in different drawings. In the following description of the embodiments of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the difference that the embodiments of the present invention are not conclusive.

In describing the components of the embodiment of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are intended to distinguish the constituent elements from other constituent elements, and the terms do not limit the nature, order or order of the constituent elements. Also, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. 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.

1 is a block diagram illustrating a configuration of an MTC data transmission system according to an embodiment of the present invention. 1 shows a cell radius of a macro cell base station 10 and a small cell base station 20 and a state where the terminal 100 is located in a cell.

In the system shown in FIG. 1, the base stations 10 and 20 can support cell synchronization through an inter-cell backhaul. This is to alleviate inter-cell interference (ICIC), FeICIC (Advanced Enhanced ICIC) and Coordinated Multi-Point / Digital Unit (CoMP / DU) problems. In addition to the function of receiving an uplink sub-frame, the base stations 10 and 20 may transmit downlink simultaneous signals for macrocells around the base station to support cell- And a function for receiving a primary synchronization signal (PSS), a secondary synchronization signal (SSS), a physical broadcast channel (PBCH), and a cell specific reference signal (CRS).

The PSS, SSS, and PBCH symbols associated with the cell synchronization of the base stations 10 and 20 are within 1.4 MBW of the base station transmission bandwidth, and the base stations 10 and 20 use the three physical channels, And can perform symbol synchronization and cell radio frame sync, SFN synchronization, and frequency offset synchronization. In addition, the base stations 10 and 20 can perform offset tracking using CRS.

When a plurality of macro cell base stations 10 and 30 and a small cell base station 20 are adjacent to each other as shown in FIG. 2, not only macro-to-small cell and Multi-RRH synchronization but also macro- Should be.

When the synchronization problem between the base stations is solved in the system structure of FIG. 1 and FIG. 2, efficient ICIC control becomes possible.

In order to solve the ICIC problem between the base station and the base station, the base station transmits PSS, SSS, PBCH, and CRS to the ABS subframe transmitted from the macrocell of a part of the downlink subframe, For example, a half-duplexing FDD mode in an area where a PSS, an SSS, a PBCH, and a CRS are not transmitted in an ABS downlink subframe in an MTC (Machine Type Communication) May be decoded and / or punctured to be transmitted to the macro cell. Here, it is assumed that the MTC data is less than 1000 bits.

In this case, not only the ICIC problem of cell communication can be solved, but resources can be utilized efficiently.

1 and 2, Ue # 0 is a terminal located in a small cell category in a macro cell, and Ue # 1 and Ue # 2 are terminals located in a macro cell. And the small cell. Here, the macro cell base stations 10 and 30 and the small cell base station 20 can perform cell synchronization such as frequency offset, symbol synchronization, and wireless frame synchronization between the respective base stations first for ICIC control.

At this time, in order to increase the data reception rate of the MTC terminal 100 located in the border area of the cell, the macro cell base station 10 inserts the ABS frame in the subframe as shown in FIG. 3A and transmits the inserted ABS frame in the downlink. Meanwhile, the small cell base station 20 transmits data corresponding to 'UE # 1' in the subframe as shown in FIG. 3B on the downlink.

In this case, the MTC terminal 100 exists in an environment where the ABS frame is transmitted in the macro cell and the downlink data of the Ue # 1 is transmitted in the small cell, such as Ue # 1 at the boundary between the base station and the base station. In this case, when the MTC terminal 100 such as Ue # 1 transmits data in the uplink using the downlink frequency band at the cell and cell boundaries, power consumption of the MTC terminal 100 is minimized The MTC data can be transmitted to the base station without interference from other terminals in the macro cell.

Herein, the MTC terminal 100 is a terminal capable of reporting a small amount of data in an uplink and processing data in an MTC data allocation area in a downlink. Further, the MTC terminal 100 can reduce the price competitiveness It is assumed that the terminal can cover a wide cell area with one antenna. In addition, the MTC terminal 100 can support a half duplex FDD function, so that it can share the uplink and downlink RF elements through the half-duplex frequency division function, it is assumed that the terminal is capable of frame control by up / down and round trip delay.

In addition, the MTC terminal 100 may further support a time division duplex (TDD) function. In this case, the MTC terminal 100 can transmit the uplink data of the MTC terminal 100 to the base station at the center frequency of the downlink, and transmit the uplink data to the base station.

For example, when the macro cell BS 10 transmits a subframe including the ABS for the UE # 1 located in the cell boundary on the downlink, when the subframe is received from the UE # 1, The RF element is already in a state where downlink frequency synchronization and symbol synchronization are already performed. Accordingly, the UE # 1 can transmit uplink data on the uplink using the downlink carrier frequency at the time of timing control through the Random Access Channel (RACH) on the uplink as in TDD do.

In this case, the MTC terminal 100 can allocate MTC uplink data to an area excluding an area allocated an initial sync symbol or subcarriers allocated a cell reference symbol in an ABS frame.

Here, since the MTC terminal 100 allocates and transmits the 1.4 M bandwidth of the center frequency instead of the entire bandwidth of the downlink, when transmitting the uplink data of the MTC terminal 100, The interference between the terminals can be minimized and the data transmission rate can be increased.

4A is a diagram illustrating a downlink ABS frame structure transmitted by a base station according to the present invention.

As shown in FIG. 4A, physical channels such as CRS, SSS, PSS, and PBCH are transmitted to the ABS downlink frame transmitted from the macro cell base station. Here, SSS, PSS, and PBCH can be transmitted using the center frequency of the 1.4M bandwidth (BW).

At this time, in addition to the ABS frame, synchronization for a backhaul between a cell and a cell may be performed using a full frame of a downlink to perform a frequency offset and a symbol sync time tracking.

On the other hand, when the MTC terminal receives the ABS frame as shown in FIG. 4A in the downlink, the MTC terminal can allocate MTC data to the ABS frame using the downlink carrier frequency, and can transmit the frame allocated with the MTC data to the uplink .

In this case, the area where the MTC data can be allocated among the downlink ABS frames shown in FIG. 4A is shown in FIG. 4B.

Referring to FIG. 4B, in the ABS frame structure, the SSS and PSS symbols are transmitted in units of 5 ms, and the PBCH is transmitted in units of 10 ms. At this time, the ABS frame can be allocated irrespective of whether the SSS, the PSS, and the PBCH are transmitted, and the base station, the LTE terminal, and the MTC terminal can acquire information on the subframe through which the SSS, PSS, can do.

Therefore, when the ABS subframe is an ABS frame in which the SSS, PSS, and PBCH symbols are not transmitted at the time of transmitting the MTC data on the uplink, the MEC UE determines whether the sub- It is possible to transmit MTC data on the entire area.

In this case, as shown in FIG. 5, the MTC terminal can transmit data on the uplink by loading MTC data as indicated by reference numeral 511 by using the center frequency of the downlink at the time point of timing control through the uplink RACH.

The operation flow of the control device according to the present invention will be described in more detail as follows.

6 is a flowchart illustrating an operation of the MTC data transmission method according to the present invention.

Referring to FIG. 6, the 'A' process shows an initial synchronization process of the MTC terminal, and the MTC terminal can receive a synchronization signal such as PSS, SSS, and PBCH from the base station on the downlink (S110) . At this time, the MTC terminal can synchronize the cell ID, symbol, radio frame and frequency of the base station through the initial synchronization process of the base station. At this time, after receiving the PBCH in step 'S120', the MTC terminal can establish SFN synchronization with the base station in the cell to which the corresponding terminal belongs.

In addition, the MTC terminal can receive the control signal and the data signal through the downlink of the base station (S130, S140). At this time, the base station may transmit the ABS frame in the downlink data subframe transmitted to the MTC terminal to control the ICIC to reach the cell boundary, and the MTC terminal may transmit the ABS frame through the SFN transmitting the ABS through the data received from the base station (S150).

In step 'S150', when the MTC terminal confirms the information on the SFN to which the ABS is transmitted, the MTC terminal transmits the RACH signal on the uplink frequency to access the base station (S160), and transmits a response thereto on the downlink (S170). At this time, the MTC terminal confirms the scheduling information on resources to be transmitted in the downlink (S180).

Thereafter, the MTC terminal allocates MTC data to the ABS frame in which the SSS, PSS, and PBCH symbols are not transmitted using the center frequency of the downlink, and transmits the subframe allocated with the MTC data to the base station through the uplink ( S200).

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention.

Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

10, 30, macro cell base station
20: Small cell base station
100: MTC terminal

Claims (1)

A base station that is synchronized with a base station located in a neighboring macro cell or a small cell through a backhaul between cells and allocates an ABS (Almost Blank Subframe) to a subframe of the data signal and transmits the ABS in the downlink;
And a user terminal for receiving a control signal and a data signal from the base station through a downlink,
The user terminal checks the synchronization information of the physical channel included in the ABS allocated to the subframe of the data signal, and assigns MTC (Machine Type Communication) data to an area of the ABS subframe to which the physical channel symbol is not allocated And transmits the uplink data through an uplink through a downlink carrier frequency.

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