KR20100124422A - Apparatus for reducing uplink noise in multiple-input multiple-output - Google Patents

Abstract

PURPOSE: An uplink noise reducing device of a multiple input-output system is provided to off all the antennas within the relay device and to prevent the transmission of a signal to all uplinks if an active terminal does not exists within the jurisdiction district of relevant relay device in a MIMO communication net, thereby preventing the increase of the uplink noise. CONSTITUTION: A plurality of receiving signal measurements(11A~11M) respectively measures the quality of a terminal signal. If a quality value of corresponding receiving signal is smaller than a first dreche threshold, a plurality of antenna switch controllers(12A~12M) offs the switch which is connected between corresponding receiving antenna and a power amplifier. A plurality of transmission power measure devices(13A~13M) measures the electric energy of an output signal to the transmission antenna from a plurality of power amplifiers. If a power value of a corresponding transmission signal is bigger than a second dreche second threshold, a plurality of different antenna switch controllers(14A~14M) offs the corresponding switch.

Description

 Uplink Noise Reduction Device for Multiple Input / Output System {APPARATUS FOR REDUCING UPLINK NOISE IN MULTIPLE-INPUT MULTIPLE-OUTPUT}

The present invention relates to a technique for reducing uplink noise in a multiple-input multiple-output (MIMO) communication network, and is particularly unnecessary in a system having a plurality of repeaters having a plurality of antennas and terminals having a plurality of antennas. The present invention relates to an uplink noise reduction device of a multiple input / output system capable of selectively turning off an antenna to reduce uplink noise.

The existing wireless wireless communication system mainly used voice service, and mainly used channel coding to overcome the channel poorness. However, as the demand for high-quality multimedia services that can be connected to anyone at any time, anywhere, the center of gravity shifts from the existing voice center to the data center, and in order to realize this technology, a technology that transfers a large amount of data faster and with less error is required. Required. Unfortunately, the mobile communication environment distorts the signal significantly due to the effects of multipath, shading effects, attenuation, and interference. In particular, fading due to multipath causes severe distortion of the signal due to the sum of signals having different magnitudes and phases received through different paths. This fading phenomenon is one of the problems that high speed digital communication has to solve. One technique that emerged to solve this problem is the MIMO system.

   The MIMO system is a type of system that is developed from the existing single input single output (SISO) system and uses a plurality of antennas of a transmitter and a receiver. It is basic to send and receive several signals through multiple antennas at once, and this allows the advantage of being able to transmit more data than conventional systems without increasing the bandwidth. The interpretation of the MIMO system is based on the SISO system.

1 is a configuration diagram of a MIMO system, as shown in FIG. 1, in which a plurality of terminals MS_K + 1 to MS_K + L are configured to perform wireless communication with a base station BS through a plurality of repeaters REP_1 to REP_M. . (The terminals of MS_1 ~ MS_K are directly connected to the base station without going through the repeater.)

Underground car parks, underground shops, tunnels, subways, interior spaces of buildings, etc., are not economically suitable to provide services using base stations that are usually installed outdoors. In such a case, the repeaters REP_1 to REP_M are used to extend the coverage.

In the downlink, the repeaters REP_1 to REP_M amplify a signal received from the base station BS and transmit the amplified signal to the terminal MS_K + 1 to MS_K + L. On the contrary, in the uplink, the repeaters REP_1 to REP_M amplify a signal received from the terminal MS_K + 1 to MS_K + L and transmit the amplified signal to the base station BS.

However, in the case of uplink, as the number of repeaters connected to the base station increases, the influence of background noise increases, thereby reducing the uplink capacity. In addition, when a plurality of repeaters are included in one base station, uplink noise may be combined at the base station receiver, thereby causing a serious problem of uplink noise enhancement.

Nevertheless, the conventional multi-input and output system has a problem that the communication service quality is lowered because the proper function for reducing the uplink noise is not provided.

Accordingly, a first object of the present invention is to allow a repeater to be turned on only when at least one terminal existing in the jurisdiction of the repeater is active.

A second object of the present invention is to prevent excessive output from being transmitted to the base station due to oscillation or the like in the repeater.

A third object of the present invention is to selectively turn on only necessary antennas when there is an active terminal in a jurisdiction of a repeater so that unnecessary uplink noise increase does not occur.

The objects of the present invention are not limited to the above-mentioned objects. Other objects and advantages of the invention will be more clearly understood by the following description.

The present invention for achieving the above object,

A plurality of received signal measuring units for measuring the quality of signals received from the terminal through a plurality of receiving antennas and outputting quality values of the respective received signals accordingly;

When the quality value of the received signal is smaller than the first threshold value, the quality value of the received signal output from the plurality of received signal measuring instruments is compared with the preset first threshold value, respectively. A plurality of antenna switch controllers for turning off the switches connected between the amplifiers;

A plurality of transmission power measuring units for measuring the amount of power of each signal output from the plurality of power amplifiers to a transmitting antenna and outputting a power value accordingly;

The power value of each of the transmission signal output from the transmission power meter is compared with the preset second threshold value, and if the power value of the corresponding transmission signal is greater than the second threshold value, a plurality of other plurality of switches to turn off the switch; And an antenna switch controller.

Received signal smaller than the third threshold value is a signal that does not contribute significantly to the improvement of the final received signal even if it is transmitted to the base station because the signal quality is not good even though the received signal level itself measured by the received signal measuring device is a certain level. Means a signal with quality.

Preferably, the quality value of the signal received from the terminal through the plurality of receiving antennas is received signal strength (RSSI) or signal-to-interference noise ratio (SINR).

Preferably, the first threshold value is set slightly lower than the quality value of the received signal output from the plurality of received signal measuring instruments when one or more active terminals exist in the jurisdiction of the corresponding repeater.

Preferably, the plurality of antenna switch controllers compare the quality values of the signals output from the plurality of reception signal measuring devices with preset third threshold values, and the quality values of the corresponding reception signals are greater than the third threshold values. If it is small, the operation of turning off the corresponding switch is performed in parallel.

Preferably, the second threshold value is set to a maximum output value of a transmission signal output when the repeater operates normally.

In the present invention, when there is no active terminal in the jurisdiction of the repeater in the MIMO communication network, all antennas in the repeater are turned off so that signals are not transmitted in all uplinks, so that signals are transmitted in an uplink unnecessarily. The link noise is increased, thereby reducing the capacity.

In addition, when the power value of the transmission signal is greater than or equal to the threshold value, by turning off the transmission antenna, the excessive output (oscillation signal) due to the malfunction of the repeater is blocked from being transmitted to the base station, thereby preventing the uplink capacity reduction due to the oscillation signal There is.

In addition, even if there is at least one active terminal in the jurisdiction of the repeater, by selectively turning on and off the antenna according to the quality of the signal received through the receiving antenna, it is effective to effectively prevent the increase in the amount of link noise have.

In the case of using the present invention, an in-building distributed antenna system (DAS) in which numerous repeaters are connected to one base station for in-building coverage in repeaters used in various places where the base station signal does not reach, and particularly in a high-rise building. It is expected that the construction of MIMO communication network in various fields will have a great effect on uplink capacity protection.

In addition, the present invention is not limited to a specific multiple access scheme, but has an advantage that can be applied to various systems such as CDMA and OFDMA.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram of an uplink noise reduction device of a multi-input / output system according to the present invention. As shown therein, receiving antennas N _rx.R1 to N _rx.RM , switches SW_1 to SW_M, Power amplifiers PA_1 to PA_M, transmitting antennas N _tx.R1 to N _tx.RM , receiving signal measuring devices 11A to 11M, antenna switch controllers 12A to 12M, and transmitting power measuring devices 13A. 13M) and antenna switch controllers 14A to 14M.

When all of the switches SW_1 to SW_M are on (shorted), the signal received from the terminal through the receiving antennas N _rx.R1 to N _rx.RM is transmitted through the switches SW_1 to SW_M, respectively. It is transmitted to (PA_1 ~ PA_M) and amplified to an appropriate level and then transmitted to the base station through the corresponding transmission antenna (N _tx.R1 ~ N _tx.RM ).

However, in the present invention, as shown in the following description, the switches SW_1 to SW_M are selectively turned on and off to selectively transmit the received signals.

First, the operation of blocking the uplink signal in the repeater according to whether one or more active terminals exist in the jurisdiction of the repeater will be described below.

To this end, the reception signal measuring devices 11A to 11M measure the quality of the signal received through the reception antennas N _rx.R1 to N _rx.RM and output the quality values CQ_1 to CQ_M of the measured reception signals. do. The quality value of the received signal may be a received signal strength indicator (RSSI) or a signal to interference and noise ratio (SINR).

In this case, the antenna switch controllers 12A to 12M compare the quality values CQ_1 to CQ_M of the reception signals measured by the reception signal measuring devices 11A to 11M with the preset first threshold value TH1, respectively. The antenna switch controller whose quality value of the received signal is found to be smaller than the first threshold value TH1 turns off the corresponding switch among the switches SW_1 to SW_M, and the antenna switch controller which turns out to be large turns on the switch. .

In general, when one or more active terminals exist in the jurisdiction of the repeater, the antenna switch controllers 12A to 12M show the quality values of the received signals measured by the reception signal measuring devices 11A to 11M as a result of the comparison. CQ_1 to CQ_M become larger than the first threshold value TH1. Accordingly, all of the switches SW_1 to SW_M are turned on.

As a result, when one or more active terminals exist in the jurisdiction of the repeater, the switches SW_1 to SW_M are all turned on through the above process. Accordingly, a signal received from any one or more terminals through the reception antennas N _rx.R1 to N _rx.RM is set to an appropriate level in the power amplifiers PA_1 to PA_M through the switches SW_1 to SW_M, respectively. After amplification, the _signal is transmitted to the base station through the corresponding transmission antennas N _tx.R1 to N _tx.RM.

On the contrary, when no active terminal exists in the jurisdiction of the repeater, the switches SW_1 to SW_M are all turned off through the above process. For this reason, no signal is transmitted from the corresponding repeater to the uplink. As a result, unnecessarily a signal is transmitted on the uplink, so that uplink noise is increased, thereby preventing the phenomenon of decreasing capacity.

On the other hand, the operation of preventing excessive output (oscillation signal) from being transmitted to the base station due to the malfunction of the repeater will be described.

To this end, the transmission power measuring devices 13A to 13M respectively amplify the power level of the signal output to the corresponding transmission antennas N _tx.R1 to N _tx.RM after being amplified to an appropriate level in the power amplifiers PA_1 to PA_M. It measures and outputs the power values PWR_1 to PWR_M of the measured transmission signal.

The antenna switch controllers 14A to 14M compare the power values PWR_1 to PWR_M of the transmission signals measured by the transmission power measuring devices 13A to 13M with the preset second threshold value TH2, respectively. In the antenna switch controller found to be greater than the value of the second threshold TH2, the signal is turned off among the switches SW_1 to SW_M, and the antenna switch controller turned out to be turned on. Therefore, the transmission signal larger than the second threshold value TH2 is blocked by the corresponding switch.

In general, when the power value of any of the power values PWR_1 to PWR_M of the transmission signal or the total power value is larger than the preset second threshold value TH2, the repeater malfunctions. In this case, some or all of the signals transmitted through the transmitting antennas N _tx.R1 to N _tx.RM are blocked through the above process.

In this way, excessive output (oscillation signal) due to the malfunction of the repeater is blocked from being transmitted to the base station, thereby preventing uplink capacity reduction due to the oscillation signal.

On the other hand, even if there is at least one active terminal in the jurisdiction of the repeater, the operation of selectively turning on and off the antenna according to the quality of the signal received through the receiving antenna (N _rx.R1 ~ N _rx.RM ) It will be described as follows. This process is similar to the process of blocking the uplink signal in the repeater depending on whether one or more active terminals exist in the jurisdiction of the corresponding repeater, but the applied signal quality or threshold value may be different. have.

The reception signal measuring devices 11A to 11M measure the quality of the signal received through the reception antennas N _rx.R1 to N _rx.RM and output the quality values CQ_1 to CQ_M of the measured reception signal. . The quality value of the received signal may be received signal strength (RSSI) or signal-to-interference noise ratio (SINR). However, when receiving signal strength (RSSI) is used as the quality of the received signal when determining whether there is at least one active terminal in the jurisdiction of the repeater, the antenna is selectively turned on or off according to the quality of the received signal. It is preferable to use the signal-to-interference noise ratio (SINR) as the quality of the received signal.

In this case, the antenna switch controllers 12A to 12M compare the quality values CQ_1 to CQ_M of the received signals measured by the reception signal measuring devices 11A to 11M, respectively, with preset third threshold values TH3. Therefore, in the antenna switch controller whose quality value of the corresponding received signal is found to be smaller than the third threshold value TH3, the corresponding switch is turned off among the switches SW_1 to SW_M. Turn on. Although the signal of which the quality value of the corresponding reception signal is smaller than the third threshold value TH3 is the received signal level itself measured by the reception signal measuring device, even if the signal quality is not excellent, the final reception signal is transmitted even though it is transmitted to the base station. It means a signal having a signal quality that does not contribute significantly to the performance improvement.

In the MIMO communication network, if one or more terminals exist in the corresponding relay jurisdiction, all M transmitting antennas (N _tx.R1 to N _tx.RM ) are turned on, and if the number of repeaters operating in this way is greater than or equal to AOS (AOS: Even if Automatic On-off Switching is applied, the uplink noise increase may be too large to be ignored.

For example, if K repeaters are turned on among M MIMO repeaters with AOS functions and N transmit antennas in the MIMO communication network, the effect of these repeaters on the uplink noise increase is K ㅧ N. This effect may be greater than M, the effect on the uplink noise amplification when all M SISO repeaters are turned on in the SISO network (K 통신 N> M).

Therefore, by using the same process as described above, by removing the unnecessary antennas from the transmitting antennas (N _tx.R1 ~ N _tx.RM ) without interrupting the relay operation of the MIMO repeater, the content link noise increase phenomenon It can be prevented efficiently.

In the above description, the receiving antennas (N _rx.R1 to N _rx.RM ) are separate from the process of blocking the uplink signal at the repeater according to whether one or more active terminals exist in the jurisdiction of the corresponding repeater. The process of selectively turning on and off the antennas according to the quality of the signal received through the above has been described as an example, but these may be integrated as necessary.

In this case, one of the received signal strength (RSSI) and the signal-to-interference noise ratio (SINR) is commonly used as the quality of the received signal, and the first and third threshold values TH1 and TH3 are unified. Used as the value of.

Although the preferred embodiment of the present invention has been described in detail above, the scope of the present invention is not limited thereto, and may be implemented in various embodiments based on the basic concept of the present invention defined in the following claims. Such embodiments are also within the scope of the present invention.

1 is an overall block diagram of a multiple input and output system according to the prior art.

2 is a block diagram of an uplink noise reduction apparatus of a multi-input / output system according to the present invention.

*** Description of the symbols for the main parts of the drawings ***

N _rx.R1 ~ N _rx.RM : _Reception antenna

SW_1 ~ SW_M: switch,

PA_1 ~ PA_M: Power Amplifier

N _tx.R1 ~ N _tx.RM : Transmission antenna

11A ~ 11M: Receive Signal Measuring Machine

12A ~ 12M: Antenna Switch Controller

13A ~ 13M: Transmission power meter

14A ~ 14M: Antenna Switch Controller

Claims (7)

In any of a plurality of repeaters installed in a multiple input and output communication network, A plurality of received signal measuring units for measuring the quality of signals received from the terminal through a plurality of receiving antennas and outputting quality values of the respective received signals accordingly; When the quality value of the received signal is smaller than the first threshold value, the quality value of the received signal output from the plurality of received signal measuring instruments is compared with the preset first threshold value, respectively. A plurality of antenna switch controllers for turning off the switches connected between the amplifiers; A plurality of transmission power measuring units for measuring the amount of power of each signal output from the plurality of power amplifiers to a transmitting antenna and outputting a power value accordingly; The power value of each of the transmission signal output from the transmission power meter is compared with the preset second threshold value, and if the power value of the corresponding transmission signal is greater than the second threshold value, a plurality of other plurality of switches to turn off the switch; An uplink noise reduction device of a multiple input / output system, comprising: an antenna switch controller. The method of claim 1, wherein the plurality of antenna switch controllers compare the quality values of the signals output from the plurality of received signal measuring devices with preset third threshold values, and the quality values of the corresponding received signals are determined by the third threshold. Uplink noise reduction device of a multiple input and output system, characterized in that to perform the operation to turn off the corresponding switch if less than the hold value. 3. The method of claim 2, wherein the received signal smaller than the third threshold value is not excellent in signal quality even if the received signal level itself measured by the received signal measuring device is constant, thereby greatly improving the performance of the final received signal even if transmitted to the base station. Uplink noise reduction device of a multiple input-output system, characterized in that the signal having a signal quality that does not contribute. The apparatus of claim 1, wherein a quality value of a signal received from the terminal through the plurality of receiving antennas is a received signal strength (RSSI) or a signal-to-interference noise ratio (SINR). The method of claim 1, wherein the first threshold value is set to be slightly lower than the quality value of the received signals outputted from the plurality of received signal measuring instruments when one or more active terminals exist in the jurisdiction of the repeater. Uplink noise reduction device of multiple input / output system. The apparatus of claim 1, wherein the transmission signal larger than the second threshold value includes an oscillation signal. The apparatus of claim 1, wherein the repeater is a repeater to which an automatic on-off switching (AOS) function is applied.

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