WO2018135853A1

WO2018135853A1 - Method for transmitting output signal and distributed antenna system for performing same

Info

Publication number: WO2018135853A1
Application number: PCT/KR2018/000797
Authority: WO
Inventors: 정만영; 양윤오; 이상욱; 임수환; 황진엽
Original assignee: 엘지전자 주식회사
Priority date: 2017-01-20
Filing date: 2018-01-17
Publication date: 2018-07-26

Abstract

Disclosed in the present specification is a distributed antenna system. The distributed antenna system comprises: a modem for generating a reference clock having a reference frequency and for transmitting, on the basis of the reference clock, transmission signals having an intermediate frequency band; and transceivers for generating an output signal, having an output frequency band, by mixing the transmission signals with the reference clock, wherein the reference clock used by the transceivers is provided from the modem and the output frequency band can be an mm-wave band.

Description

A method of transmitting an output signal and a distributed antenna system performing the method

The present invention relates to a distributed antenna system, and more particularly, to a method for transmitting an output signal using a distributed antenna system mounted on a vehicle.

With the success of long term evolution (LTE) / LTE-Advanced (LTE-A) for 4G mobile communications, interest in future mobile communications, namely 5G (so-called 5G) mobile communications, is increasing. It's going on.

The fifth generation (5G) mobile communication, defined by the International Telecommunication Union (ITU), refers to data rates of up to 20 Gbps and at least 100 Mbps anywhere in the world. Its official name is 'IMT-2020' and aims to commercialize it globally in 2020.

The ITU presents three usage scenarios, such as Enhanced Mobile BroadBand (eMBB), Massive Machine Type Communication (MMTC) and Ultra Reliable and Low Latency Communications (URLLC).

First, URLLC relates to usage scenarios that require high reliability and low latency. For example, there is a vehicle to vehicle (V2V) technology based on device to device (D2D) technology.

On the other hand, in the V2V technology vehicles, the need for a distributed antenna system is increasing in the 5G era. The distributed antenna system is an antenna system used to solve a high traffic capacity problem in an indoor environment by spatially distributing a low power antenna, and is a tower mounted amplifier (TMA) or remote radio head (RRH) applied to a conventional base station. The concept of is introduced to the vehicle terminal.

In the case of a conventional terminal, there is a correlation between transmit and receive antennas due to the limited distance between antennas. Accordingly, there is a problem in that the actual transmission / reception performance is greatly reduced compared to the transmission / reception performance theoretically obtained.

An object of the present disclosure is to provide a method for transmitting an output signal using a distributed antenna system for a vehicle.

In order to achieve the above object, one disclosure of the present specification provides a distributed antenna system. The distributed antenna system includes a modem for generating a reference clock having a reference frequency and generating transmission signals having an intermediate frequency based on the reference clock; A first transceiver configured to generate a first output signal having an output frequency band by mixing a first transmission signal among the transmission signals and the reference clock; And a second transceiver configured to generate a second output signal having an output frequency band by mixing a second transmission signal and the reference clock among the transmission signals, wherein the first transceiver and the second transceiver are used. A reference clock is provided from the modem and the output frequency band may be a millimeter wave band.

The modem includes: a baseband circuit for generating a reference clock having the reference frequency; A conversion circuit for converting a digital signal to be transmitted into an analog signal; A first antenna driver for receiving the reference clock and the analog signal and generating the first transmission signal; And a second antenna driver for receiving the reference clock and the analog signal and generating the second transmission signal, wherein the wireless transceiver, the first antenna driver and the second antenna driver are the same reference from the baseband circuit. The clock can be received.

When the insertion loss in the cable to which the first transmission signal and the second transmission signal are transmitted is not large, the first antenna driver generates the first transmission signal without changing the frequency of the analog signal, and the second The antenna driver may generate the second transmission signal without changing the frequency of the analog signal.

The modem and the first transceiver may be electrically connected through a first coaxial cable, and the modem and the second transceiver may be electrically connected through a second coaxial cable.

In order to achieve the above object, another disclosure of the present disclosure provides a method for transmitting an output signal by a distributed antenna system including a modem and a plurality of transceivers. The method includes: generating, by the modem, a reference clock having one reference frequency; Generating, by the modem, a first transmission signal and a second transmission signal having an intermediate frequency based on the reference clock; Generating, by a first transceiver, a first output signal having an output frequency band by mixing the first transmission signal and the reference clock among the plurality of transceivers; And generating, by a second transceiver, a second output signal having an output frequency band by mixing the second transmission signal and the reference clock among the plurality of antennas, wherein the first transceiver and the second transmission / reception are performed. The reference clock additionally used is provided from the modem, and the output frequency band may be a millimeter wave band.

According to one disclosure of the present specification, by generating a transmission signal using one reference clock, it is possible to prevent performance degradation of the distributed antenna system.

1 is a wireless communication system.

2 shows a structure of a radio frame according to FDD in 3GPP LTE.

3 illustrates a concept of device to device (D2D) communication that is expected to be introduced in the next generation communication system.

4 illustrates an example of D2D communication or ProSe communication between UE # 1 and UE # 2 illustrated in FIG. 3.

5 is an exemplary view illustrating the concept of V2X.

6 is an exemplary view showing a conventional modem.

7 shows the insertion loss according to the transmission frequency.

8A and 8B illustrate a distributed antenna system according to an embodiment of the present specification.

FIG. 9 shows an example of frequency allocation according to an input port of the IF multiplexer shown in FIG. 8B.

10A and 10B illustrate a distributed antenna system according to another embodiment of the present specification.

11 is a block diagram illustrating a wireless communication system in which an embodiment presented in the present specification is implemented.

It is to be noted that the technical terms used herein are merely used to describe particular embodiments, and are not intended to limit the present invention. In addition, the technical terms used in the present specification should be interpreted as meanings generally understood by those skilled in the art unless they are specifically defined in this specification, and are overly inclusive. It should not be interpreted in the sense of or in the sense of being excessively reduced. In addition, when the technical terms used herein are incorrect technical terms that do not accurately represent the spirit of the present invention, it should be replaced with technical terms that can be understood correctly by those skilled in the art. In addition, the general terms used in the present invention should be interpreted as defined in the dictionary or according to the context before and after, and should not be interpreted in an excessively reduced sense.

Also, the singular forms used herein include the plural forms unless the context clearly indicates otherwise. In the present application, terms such as “consisting of” or “having” should not be construed as necessarily including all of the various components, or various steps described in the specification, and some of the components or some of the steps are included. It should be construed that it may not be, or may further include additional components or steps.

In addition, terms including ordinal numbers, such as first and second, as used herein may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as the second component, and similarly, the second component may also be referred to as the first component.

When a component is said to be "connected" or "connected" to another component, it may be directly connected to or connected to that other component, but other components may be present in between. On the other hand, when a component is said to be "directly connected" or "directly connected" to another component, it should be understood that there is no other component in between.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings, and the same or similar components will be given the same reference numerals regardless of the reference numerals, and redundant description thereof will be omitted. In addition, in describing the present invention, when it is determined that the detailed description of the related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, it should be noted that the accompanying drawings are only for easily understanding the spirit of the present invention and should not be construed as limiting the spirit of the present invention by the accompanying drawings. The spirit of the present invention should be construed to extend to all changes, equivalents, and substitutes in addition to the accompanying drawings.

The term base station, which is used hereinafter, generally refers to a fixed station for communicating with a wireless device, and includes an evolved-nodeb (eNodeB), an evolved-nodeb (eNB), a base transceiver system (BTS), and an access point (e.g., a fixed station). Access Point) may be called.

Further, hereinafter, the term UE (User Equipment), which is used, may be fixed or mobile, and may include a device, a wireless device, a terminal, a mobile station (MS), and a user terminal (UT). Other terms may be referred to as a subscriber station (SS) and a mobile terminal (MT).

도 1은 무선 통신 시스템이다.1 is a wireless communication system.

As can be seen with reference to FIG. 1, a wireless communication system includes at least one base station (BS) 20. Each base station 20 provides a communication service for a particular geographic area (generally called a cell) 20a, 20b, 20c. The cell can in turn be divided into a number of regions (called sectors).

The UE typically belongs to one cell, and the cell to which the UE belongs is called a serving cell. A base station that provides a communication service for a serving cell is called a serving BS. Since the wireless communication system is a cellular system, there are other cells adjacent to the serving cell. Another cell adjacent to the serving cell is called a neighbor cell. A base station that provides communication service for a neighbor cell is called a neighbor BS. The serving cell and the neighbor cell are determined relatively based on the UE.

Hereinafter, downlink means communication from the base station 20 to the UE 10, and uplink means communication from the UE 10 to the base station 20. In downlink, the transmitter may be part of the base station 20 and the receiver may be part of the UE 10. In uplink, the transmitter may be part of the UE 10 and the receiver may be part of the base station 20.

Hereinafter, the LTE system will be described in more detail.

도 2는 2 is 3GPP3GPP LTE에서In LTE FDD에 따른 무선 프레임(radio frame)의 구조를 나타낸다. A structure of a radio frame according to FDD is shown.

Referring to FIG. 2, a radio frame includes 10 subframes, and one subframe includes two slots. Slots in a radio frame are numbered from 0 to 19 slots. The time taken for one subframe to be transmitted is called a transmission time interval (TTI). TTI may be referred to as a scheduling unit for data transmission. For example, one radio frame may have a length of 10 ms, one subframe may have a length of 1 ms, and one slot may have a length of 0.5 ms.

The structure of the radio frame is merely an example, and the number of subframes included in the radio frame or the number of slots included in the subframe may be variously changed.

Meanwhile, one slot may include a plurality of orthogonal frequency division multiplexing (OFDM) symbols. How many OFDM symbols are included in one slot may vary depending on a cyclic prefix (CP).

One slot includes N _RB resource blocks (RBs) in the frequency domain. For example, in the LTE system, the number of resource blocks (RBs), that is, N _RBs may be any one of 6 to 110.

A resource block (RB) is a resource allocation unit and includes a plurality of subcarriers in one slot. For example, if one slot includes 7 OFDM symbols in the time domain and the resource block includes 12 subcarriers in the frequency domain, one resource block includes 7 × 12 resource elements (REs). It may include.

<D2D(Device to Device) 통신><D2D (Device to Device) Communication>

On the other hand, D2D communication expected to be introduced in the next generation communication system will be described below.

도 3은 차세대 통신 시스템에서 도입될 것으로 기대되는 3 is expected to be introduced in the next generation communication system D2DD2D (Device to Device) 통신의 개념을 나타낸다.(Device to Device) Shows the concept of communication.

Due to an increase in user requirements for social network services (SNS), communication between physically close UEs, that is, device to device (D2D) communication, is required.

As shown in FIG. 3 to reflect the above-described requirements, between UE # 1 100-1, UE # 2 100-2, UE # 3 100-3, or UE # 4 100-. 4), a method of allowing direct communication between the UE # 5 (100-5) and the UE # 6 (100-6) without the involvement of the base station (eNodeB) 200 has been discussed. Of course, the UE # 1 100-1 and the UE # 4 100-4 may directly communicate with the help of the base station (eNodeB) 200. Meanwhile, the UE # 4 100-4 may serve as a repeater for the UE # 5 100-5 and the UE # 6 100-6. Similarly, the UE # 1 100-1 may serve as a relay for the UE # 2 100-2 and the UE # 3 100-3 that are far from the cell center.

On the other hand, D2D communication is also called proximity service (ProSe). The UE that performs the proximity service is also called a ProSe UE. In addition, a link between UEs used for the D2D communication may be referred to as sidelink.

Physical channels used for the sidelinks are as follows.

PSSCH (Physical Sidelink Shared Channel)

Physical Sidelink Control Channel (PSCCH)

Physical Sidelink Discovery Channel (PSCH)

PSBCH (Physical Sidelink Broadcast Channel)

In addition, the physical signals used in the side link are as follows.

Demodulation Reference Signal (DMRS)

Sidelink Synchronization Signal (SLSS)

The SLSS includes a Primary Side Link Synchronization Signal (PSLSS) and a Secondary Side Link Synchronization Signal (Secondary SLSS: SSLSS).

도 Degree 4은4 is 도 3에 도시된 Shown in Figure 3 UE UE

#1과 # 1 and UE UE

#2 간의 # 2 interracial D2DD2D 통신 또는 Communication or ProSeProSe 통신의 예를 나타낸다. An example of communication is shown.

Referring to FIG. 4, the base station 200 broadcasts a system information block (SIB) in a cell.

The SIB may include information about a resource pool related to D2D communication. Information about a resource pool associated with the D2D communication may be classified into SIB type 18 and SIB type 19.

The SIB type 18 may include resource configuration information for D2D communication. In addition, the SIB type 19 may include resource configuration information related to D2D discovery.

Meanwhile, the UE # 1 100-1 located within the coverage of the base station 200 establishes an RRC connection with the base station.

The UE # 1 100-1 receives an RRC message, for example, an RRC Connection Reconfiguration message, from the base station 200. The RRC message includes a discovery configuration (hereinafter referred to as discConfig). The discConfig includes configuration information on a discovery resource pool (hereinafter referred to as DiscResourcePool).

Meanwhile, the UE # 1 100-1 detects whether a suitable UE exists in the vicinity for D2D communication or ProSe communication, or the UE # 1 100-1 indicates a presence of a detection signal, Discovery signal) may be transmitted through the PSDCH.

In addition, the UE # 1 100-1 may transmit a scheduling assignment (SA) through the PSCCH. The UE # 1 100-1 may transmit a PSSCH including data based on the scheduling assignment SA.

<V2X(VEHICLE-TO-EVERYTHIHG)><V2X (VEHICLE-TO-EVERYTHIHG)>

The aforementioned D2D information may also be applied to vehicle-to-everything (V2X). V2X collectively refers to communication technology via the vehicle and all interfaces. An implementation of V2X might look like this:

First, 'X' in V2X may be a vehicle. In this case, V2X may be referred to as vehicle-to-vehicle (V2V), and may mean communication between vehicles.

도 5는 V2X의 개념을 나타낸 예시도이다.5 is an exemplary view illustrating the concept of V2X.

As can be seen with reference to FIG. 5, vehicles (ie, wireless devices mounted on vehicles) 100-1, 100-2, and 100-3 may communicate with each other.

In the V2X, 'X' may mean a person or a pedestrian. In this case, V2X may be expressed as vehicle-to-person or vehicle-to-pedestrian (V2P). Here, the pedestrian is not necessarily limited to a person walking on foot, and may include a person riding a bicycle, a driver or a passenger (less than a certain speed) of a vehicle.

Alternatively, 'X' may be infrastructure / network. In this case, V2X may be referred to as vehicle-to-infrastructure (V2I) or vehicle-to-network (V2N), and may mean communication between a vehicle and a roadside unit (RSU) or a vehicle and a network. The roadside device may be a traffic related infrastructure, for example, a device for indicating speed. The roadside device may be implemented in a base station or a fixed terminal.

도 6은 종래의 모뎀을 나타낸 예시도이다.6 is an exemplary view showing a conventional modem.

Referring to FIG. 6, a conventional modem may include a baseband (BB) circuit, an RF transceiver, and an RF front end.

The baseband circuit may modulate the transmission data through digital signal processing, and demodulate the reception signal to restore the reception data.

The RF transceiver includes a mixer, an analog-to-digital converter (ADC), and a digital-to-analog converter (DAC), wherein the RF transceiver includes an analog signal between the baseband circuit and the RF front end. The reception signal) can be converted into a digital signal, and the digital signal (transmission signal) can be converted into an analog signal.

The RF front end may include a power amplifier (PA), a low noise amplifier (LNA), a duplexer, and a filter that are not integrated in the RF transceiver.

Typically, the baseband circuit and the RF transceiver may transmit and receive digital signals to each other according to a dedicated signal protocol of a chipset manufacturer.

On the other hand, as connected cars emerge in the 5G era, the necessity of introducing a distributed antenna system in a vehicle is increasing. By introducing the distributed system into a vehicle, a concept of a tower mounted amplifier (TMA) or remote radio head (RRH), which is conventionally applied to a base station, may be introduced into a vehicle terminal.

In the case of the conventional terminal, there was a correlation between the transmitting and receiving antennas due to the limited distance between the antennas, and accordingly, there was a problem that the actual transmitting and receiving performance was significantly lowered than the theoretically obtainable transmitting and receiving performance. By applying the system to V2V communication, the transmit / receive performance problem can be overcome.

도 7은 전송 주파수에 따른 삽입 손실을 나타낸다.7 shows the insertion loss according to the transmission frequency.

Referring to FIG. 7, it can be seen that the insertion loss of the RF cable increases as the transmission frequency increases. Therefore, when building a distributed antenna system in the high frequency band, the insertion loss of the RF cable increases, antenna performance may be reduced, and antenna construction cost may increase.

Recently, wireless communication systems are being actively constructed in high frequency bands to easily secure wideband frequencies. In the case of introducing a distributed antenna system to a modem used for V2V communication of a vehicle, the following form may be considered.

	성성능Performance	구현avatar		비고Remarks
	성성능Performance	비용cost	난이도difficulty	비고Remarks
RF 안테나 분산RF antenna dispersion	하Ha	중medium	하Ha	높은 주파수를 적용함에 따라 RF 케이블 비용이 증가케이블 삽입에 따른 손실 증가로 인한 성능 저하가 가장 큼RF cable costs increase with higher frequencies, resulting in the greatest loss of performance due to increased losses due to cable insertion
RF 프런트 엔드 분산RF front-end distribution	중medium	상Prize	중medium	높은 주파수를 적용함에 따라, RF 케이블이 증가하고, 분산형 안테나마다 복수의 RF 케이블(Tx/Rx)이 요구됨으로 인해 구현 비용이 증가.RF 안테나만 분산 하는 경우에 비해 RF 안테나와 인접한 LNA로부터의 수신 성능을 보완했지만, RF 케이블 삽입 손실의 증가로 인한 성능 저하가 여전히 발생됨The application of higher frequencies increases RF cables and increases implementation costs by requiring multiple RF cables (Tx / Rx) for each distributed antenna. Complemented reception, but performance degradation still occurs due to increased RF cable insertion loss
RF 송수신기 분산RF transceiver distribution	상Prize	중medium	상Prize	단말 칩셋 제조 업체가 분산형 안테나 시스템을 위한 전용 RF 송수신기를 구현할 필요가 있음Terminal chipset manufacturers need to implement dedicated RF transceivers for distributed antenna systems
모뎀 분산Modem distributed	중medium	상Prize	하Ha	분산형 안테나들 각각이 독립된 모뎀으로 구성되며, 각 모뎀이 수신한 데이터를 상위 계층에서 결합하는 형태로 구현되므로, 네트워크에서 관련 기능 및 과금 체계에 대한 고려가 필요함.Each distributed antenna is composed of independent modems, and each modem is implemented in the form of combining the received data at a higher layer. Therefore, consideration of related functions and charging schemes in the network is necessary.

Referring to Table 1, the insertion loss of the RF cable increases in proportion to the frequency, and accordingly, an increase in the cost of using an expensive RF cable may be a problem.

Therefore, referring to FIG. 7 and Table 1, when constructing a distributed antenna system in a high frequency band, an RF antenna distribution method or an RF front end distribution method may be appropriate due to performance degradation and cost increase due to insertion loss of an RF cable. I can't.

That is, referring to Table 1, although the performance of the distributed antenna system of the RF transceiver distributed method is actually the best, considering that the baseband circuit and the RF transceiver of the terminal is composed of one chipset, the terminal chipset manufacturer Unless we implement a dedicated RF transceiver for a distributed antenna system, the practical implementation is difficult.

In addition, the distributed antenna system of the RF transceiver distributed method transmits a digital signal directly to the distributed antenna, the distributed antenna can generate an analog signal itself. However, when each of the distributed antennas uses a reference clock generated from different oscillators, performance may be degraded due to the frequency offset of each oscillator, and in particular, the number of distributed antennas As the value increases, the range of performance degradation may increase.

In addition, referring to Table 1, in the case of a modem distributed method, since a distributed antenna includes a plurality of different modems embedded therein and combines the transmit / receive data of each modem in an upper layer, Measures to deal with (eg, dedicated server installation, etc.) may be required. In addition, in the case of the modem distributed scheme, only the gain due to selective combining occurs in terms of performance. Therefore, considering the cost and performance, the modem distributed scheme may not be an appropriate scheme.

<본 명세서의 개시>Disclosure of the Invention

In this specification, in consideration of these points, a distributed antenna system of the following type is proposed. According to the method proposed in the present disclosure, while using a conventional modem composed of a baseband circuit and an RF transceiver as it is possible, the distributed antenna by changing the output frequency of the RF transceiver to an intermediate frequency band, which is advantageous for analog signal transmission Each of the distributed antennas may be finally converted to a transmission / reception frequency and then transmitted.

도 8a 및 도 8b는 본 명세서의 일 실시 예에 따른 분산형 안테나 시스템을 나타내고, 도 9는 도 8b에 도시된 IF 멀티플렉서의 입력 포트에 따라 주파수 배치 예를 나타낸다.8A and 8B illustrate a distributed antenna system according to an exemplary embodiment of the present disclosure, and FIG. 9 illustrates an example of frequency allocation according to an input port of an IF multiplexer illustrated in FIG. 8B.

FIG. 8A illustrates a modem included in a distributed antenna system implemented in a frequency-division duplex (FDD) scheme, and FIG. 8B illustrates an antenna unit included in a distributed antenna system implemented in a FDD scheme. According to an embodiment, the distributed antenna system illustrated in FIGS. 8A and 8B may be a distributed antenna system for a vehicle.

Part A and B shown in FIG. 8A may be physically / functionally connected to part A and B shown in FIG. 8B, respectively.

Description of each frequency shown in FIGS. 8A and 8B is as follows.

f_ref: The output frequency of the voltage-controlled crystal oscillator controlled by the modem's automatic frequency controller (AFC), which can be sent to the RF transceiver, antenna driver, and RF front end to be used as the reference frequency for the RF transceiver, antenna driver, and RF front end. have.

f_IF_U / f_IF_D: A frequency of an intermediate frequency band for transmitting a UL / DL signal in a cable (eg, a coaxial cable), and may be selected in consideration of the attenuation characteristics of the analog filter of the cable and the IF multiplexer.

f_CU / f_CD: UL / DL carrier frequency used for an output signal transmitted and received by a terminal to a base station

f_PLL_U2 / F_PLL_D2: In the IF multiplexer of the RF transceiver, the PLL of the RF front-end generates the RF front end based on the reference frequency (f_ref) to convert the frequency of the transmitted signal transmitted over the cable to the UL / DL carrier frequency f_CU / f_CD. As the frequency of the signal, it can be sent to the mixer. The following equation may be established between f_PLL_U2 / F_PLL_D2 and f_IF_U / f_IF_D.

f_tmp_U / f_tmp_D: A frequency of a UL / DL analog signal generated by an RF transceiver of a modem, and may be a frequency having good characteristics among frequency bands supported by the RF transceiver. When the antenna driver transmits a signal generated by the RF transceiver to the RF front end through a cable without changing the frequency using a mixer, the following equation may be established.

f_PLL_U1 / f_PLL_D1: This may be a frequency generated by the PLL of the antenna driver and transmitted to the mixer. It is used to change the frequency of the analog signal received from the RF transceiver to the intermediate frequency band, the following equation can be established.

8A and 8B, a distributed antenna system may include a modem and a plurality of RF front ends. The modem may include a baseband circuit (BB), a voltage controlled crystal oscillator (VCXO), a control signal generator, an RF transceiver, and a plurality of antenna drivers.

The baseband circuit BB may modulate the transmission data through digital signal processing, and demodulate the reception signal to restore the reception data. The baseband circuit BB may control the reference clock output from the voltage controlled crystal oscillator VXO using the AFC.

The voltage controlled crystal oscillator VCXO may adjust the frequency f_ref of the reference clock CLK_ref under the control of the baseband circuit BB. The voltage controlled crystal oscillator VCXO may transmit the reference clock CLK_ref to an RF transceiver and a plurality of antenna drivers.

The reference frequency f_ref of the reference clock CLK_ref may be controlled by an automatic frequency controller (AFC) of the modem. The reference clock CLK_ref may be transmitted to the RF front end through a cable without changing the frequency.

The RF transceiver may receive a digital signal from a baseband circuit BB, convert it into an analog signal, and convert an analog signal transmitted through the plurality of antenna drivers into a digital signal. The RF transceiver may transmit a first transmission signal generated by converting a digital signal from a baseband circuit BB to a first antenna driver, and transmit a second transmission signal to a second antenna driver.

The plurality of antenna drivers may be connected to a plurality of RF front ends via a cable. Each of the plurality of antenna drivers may include a phase locked loop (PLL), a mixer, and an IF multiplexer. The frequency of the transmission signal transmitted by the plurality of antenna drivers to the RF front end via a cable may be an intermediate frequency band.

The intermediate frequency band may be determined in consideration of the required frequency band and frequency, attenuation characteristics, and the implementation complexity of the multiplexer in the entire system, and the intermediate frequency band takes the necessary frequency band and frequency, the attenuation characteristic, and the implementation complexity of the multiplexer in the entire system into consideration. The resultant frequency may be the lowest frequency band.

The PLL may receive a reference clock from a voltage controlled crystal oscillator (VCXO) and tune the received reference clock.

The mixer may mix the transmission signal (first transmission signal or second transmission signal) received from the RF transceiver with the tuned reference clock received from the PLL.

The IF multiplexer may receive a control signal, a transmission signal (a first transmission signal or a second transmission signal), a reference clock, and a direct current power supply (DC), and transmit the received signal received through a cable to an RF transceiver. The IF multiplexer can pass a reference clock with a reference frequency (f_ref) through the cable to the RF front end. The reference frequency f_ref may be a frequency band of 20 MHz or less.

On the other hand, if each of the RF front ends has a different reference frequency (that is, each of the antenna drivers to generate a reference clock independently), each of the RF front ends may have a different frequency offset (offset). In this case, a performance degradation may occur due to different frequency offsets, and thus, the method proposed in this specification may be caused by having a different reference frequency for each RF front end as in the RF transceiver distribution method described in Table 1 above. This can compensate for any performance degradation.

The IF multiplexer refers to a duplexer, quadplexer or hexaplexer, and may be configured by combining a plurality of band pass filters.

The transmitted signal can be converted to an intermediate frequency band and transmitted to the RF front end via a cable. According to an embodiment, the cable may be a coaxial cable.

The control signal generator may generate a control signal Ctrl according to the control of the baseband circuit BB. The control signal generator may transmit the generated control signal Ctrl to the antenna driver.

The control signal Ctrl may be transmitted to the antenna driver through a digital cable separate from the cable. Considering the distance from the modem to the antenna and the number of cables, serial control may be advantageous for the control signal Ctrl. When the control signal Ctrl is transmitted through a cable for transmitting the transmission signal, a separate signal conversion technique may be required to exclude that the control signal Ctrl, which is a digital signal, affects the transmission / reception signal, which is an analog signal. . According to an embodiment, the signal conversion technique may be a combination of Manchester coding and a band-limited filter.

DC power (DC) may be transmitted separately from the cable, or may be transmitted through the cable. The method of transmitting the DC power source DC may be determined in consideration of the cost of implementing the multiplexer port required for transmitting the DC power source DC. When the DC power DC is transmitted through the cable, the DC power DC may be separated from the transmitted / received signal by using a low pass filter LPT at the end.

According to an embodiment, when the RF cable insertion loss in the lowest frequency band supported by the RF transceiver is not large, the antenna driver may transmit to the RF front end without changing the frequency of the transmission signal received from the RF transceiver. That is, if the frequency of the transmission signal transmitted by the antenna driver to the RF front end through the cable corresponds to the lowest frequency band among the frequencies supported by the RF transceiver, the antenna driver may turn on the mixer if the loss in the cable is not large. The transmission signal can be transmitted to the antenna circuit without mixing the reference signal and the transmission signal output from the RF transceiver. This can reduce implementation costs.

That is, when the RF transceiver supports a sufficiently low frequency band that can be transmitted in the cable, the antenna driver can transmit the transmission signal to the RF front end without omitting the mixing of the transmission signal using the mixer and the PLL.

Each of the plurality of RF front ends may include an IF multiplexer, a PLL, a micro controller unit (MCU), a power amplifier (PA), a low-noise amplifier (LNA), a mixer, and an RF duplexer.

The RF front end can be connected to the antenna driver via a cable. The RF front end may convert the frequency of the transmission signal received from the antenna driver to generate an output signal, and transmit the output signal through the antenna. The output signal may be mm wave.

The IF multiplexer at the RF front end can receive transmit signals, reference clocks, control signals, and direct current power from the antenna driver, and receive signals through the antenna. The IF multiplexer may transmit a transmission signal received from the antenna driver to the mixer, transmit a reference clock to the PLL, transmit a control signal to the MCU, and transmit the received signal to the antenna driver through a cable.

The PLL of the RF front end may have the same function as the PLL of the antenna driver.

The mixer at the RF front end may mix the reference clock and the transmitted signal and transmit it to the PA. The PA may amplify the mixed signal to generate an output signal (carrier).

The LNA can amplify the received signal received by the antenna.

That is, the distributed antenna system described with reference to FIGS. 8A and 8B minimizes a change in the configuration of a modem composed of a conventional baseband circuit and an RF transceiver, and converts the frequency of the output of the RF transceiver into an intermediate frequency band for analog signal transmission. Can change and send. Distributed antennas may transmit the frequency of the output of the RF transceiver having an intermediate frequency band to a frequency capable of transmitting and receiving.

도 10a 및 도 10b는 본 명세서의 다른 실시 예에 따른 분산형 안테나 시스템을 나타낸다.10A and 10B illustrate a distributed antenna system according to another embodiment of the present specification.

10A and 10B illustrate a distributed antenna system implemented in a time-division duplex (TDD) scheme, unlike FIGS. 8A and 8B. That is, FIG. 10A illustrates a modem included in a distributed antenna system implemented in a TDD scheme, and FIG. 10B illustrates an antenna unit included in a distributed antenna system implemented in a TDD scheme. According to an embodiment, the distributed antenna system illustrated in FIGS. 10A and 10B may be a distributed antenna system for a vehicle.

As shown in FIG. 10A, the modem of the distributed antenna system implemented by the TDD scheme may have the same configuration and function as the modem of the distributed antenna system implemented by the FDD scheme illustrated in FIG. 8A.

Also, except that an RF duplexer is used in the distributed antenna system implemented in the FDD scheme illustrated in FIG. 8B, but an RF switch is used in the distributed antenna system implemented in the TDD scheme illustrated in FIG. 10B. The antenna unit of 10b may have the same configuration and function as the antenna unit of FIG. 8B.

That is, since the antenna unit shown in FIG. 8B is operated in the FDD scheme, a duplexer is required to distinguish transmission and reception signals transmitted and received at the same time. However, the antenna unit shown in FIG. RF switches that are switched may be required. Therefore, instead of the RF duplexer of the antenna unit of the FDD scheme shown in FIG. 8B, only the part in which the antenna unit of the TDD scheme illustrated in FIG. 10B includes an RF switch may be different.

Part A and B shown in FIG. 10A may be physically / functionally connected to part A and B shown in FIG. 10B, respectively.

The contents described so far can be implemented in hardware.

도 11은 본 명세서에서 제시된 실시 예가 구현되는 무선통신 시스템을 나타낸 블록도이다. 11 is a block diagram illustrating a wireless communication system in which an embodiment presented in the present specification is implemented.

The base station 200 includes a processor 201, a memory 202, and an RF unit 203. The memory 202 is connected to the processor 201 and stores various information for driving the processor 201. The RF unit 203 is connected to the processor 201 to transmit and / or receive a radio signal. The processor 201 implements the proposed functions, processes and / or methods. In the above-described embodiment, the operation of the base station may be implemented by the processor 51.

The terminal 100 includes a processor 101, a memory 102, and an RF unit 103. The memory 102 is connected to the processor 101 and stores various information for driving the processor 101. The RF unit 103 is connected to the processor 101 and transmits and / or receives a radio signal. The processor 101 implements the proposed functions, processes and / or methods. In the above-described embodiment, the operation of the wireless device may be implemented by the processor 101.

The processor may include application-specific integrated circuits (ASICs), other chipsets, logic circuits, and / or data processing devices. The memory may include read-only memory (ROM), random access memory (RAM), flash memory, memory card, storage medium and / or other storage device. The RF unit may include a baseband circuit for processing a radio signal. When the embodiment is implemented in software, the above technique may be implemented as a module (process, function, etc.) for performing the above-described function. The module may be stored in memory and executed by a processor. The memory may be internal or external to the processor and may be coupled to the processor by various well known means.

In the exemplary system described above, the methods are described based on a flowchart as a series of steps or blocks, but the invention is not limited to the order of steps, and certain steps may occur in a different order or concurrently with other steps than those described above. Can be. In addition, those skilled in the art will appreciate that the steps shown in the flowcharts are not exclusive and that other steps may be included or one or more steps in the flowcharts may be deleted without affecting the scope of the present invention.

Claims

In a distributed antenna system,

A modem generating a reference clock having a reference frequency and generating transmission signals having an intermediate frequency based on the reference clock;

A first transceiver configured to generate a first output signal having an output frequency band by mixing a first transmission signal among the transmission signals and the reference clock; And

A second transceiver configured to generate a second output signal having an output frequency band by mixing a second transmission signal of the transmission signals with the reference clock,

The reference clock used by the first transceiver and the second transceiver is provided from the modem,

And said output frequency band is a millimeter wave band.
The method of claim 1, wherein the modem,

A baseband circuit for generating a reference clock having the reference frequency;

A transceiver for converting a digital signal to be transmitted into an analog signal;

A first antenna driver for receiving the reference clock and the analog signal and generating the first transmission signal; And

A second antenna driver for receiving the reference clock and the analog signal and generating the second transmission signal,

The wireless transceiver, the first antenna driver and the second antenna driver receives the same reference clock from the baseband circuit.
The method of claim 2, wherein the insertion loss in the cable to which the first transmission signal and the second transmission signal are transmitted is not large.

The first antenna driver generates the first transmission signal without changing the frequency of the analog signal, and the second antenna driver generates the second transmission signal without changing the frequency of the analog signal.
According to claim 1,

The modem and the first transceiver are electrically connected through a first coaxial cable,

And the modem and the second transceiver are electrically connected through a second coaxial cable.
A method of transmitting an output signal by a distributed antenna system including a modem and a plurality of transceivers,

Generating, by the modem, a reference clock having one reference frequency;

Generating, by the modem, a first transmission signal and a second transmission signal having an intermediate frequency based on the reference clock;

Generating, by a first transceiver, a first output signal having an output frequency band by mixing the first transmission signal and the reference clock among the plurality of transceivers; And

Generating a second output signal having an output frequency band by mixing, by the second transceiver, the second transmission signal and the reference clock among the plurality of antennas;

The reference clock used by the first transceiver and the second transceiver is provided from the modem,

Wherein said output frequency band is a millimeter wave band.
The method of claim 5,

Converting a digital signal to be transmitted into an analog signal using the reference clock;

Wherein the first transmission signal and the second transmission signal are generated based on the reference clock and the analog signal.
The method of claim 2, wherein the insertion loss in the cable to which the first transmission signal and the second transmission signal are transmitted is not large.

The first antenna driver generates the first transmission signal without changing the frequency of the analog signal, and the second antenna driver generates the second transmission signal without changing the frequency of the analog signal.
The method of claim 5,

The modem and the first transceiver are electrically connected through a first coaxial cable,

And the modem and the second transceiver are electrically connected through a second coaxial cable.