KR200328572Y1 - An Interference Cancellation Antenna and a RF Repeater having the Interference Cancellation Antenna - Google Patents

Abstract

The present invention improves the isolation between antennas in areas with high interference by surrounding buildings, such as urban areas, to reduce interference between antennas and wireless repeaters using the interference cancellation antennas. The interference canceling antenna according to the present invention includes a plurality of first dipole elements directed in a forward direction; A plurality of second dipole elements directed in a rearward direction; A feeder supplying a signal to be radiated into the air through the first and second dipole elements; And located between the feed line and the first and second dipole elements, to distribute signals supplied from the feed line to the first and second dipole elements, respectively, wherein a phase is applied to the signal distributed to the second dipole element. It characterized in that it comprises a directional coupler to reverse the 180 °.

Description

An interference cancellation antenna and a RF repeater having the interference cancellation antenna

The present invention relates to the elimination of interference waves generated by the signal transmitted from the transmitting antenna of the wireless repeater back to the receiving antenna due to the reflection of the surrounding environment. An interference cancellation antenna for improving the isolation between antennas in a region to be suitable for a high gain wireless repeater and a wireless repeater using the interference cancellation antenna.

In a wireless network of a mobile communication system, there are partial shaded areas where radio waves are weak due to natural and artificial obstacles such as mountains, buildings, basements of buildings, tunnels, interiors of buildings, etc., and thus the terminal cannot be received. Will be created. Radio repeater (RF Repeater) is a system that covers the shadow area existing within the service range of the base station by re-amplifying the base station signal, and relays the system to receive high quality service anytime and anywhere. A donor antenna for transmitting and receiving wireless signals with a base station and a service antenna for transmitting and receiving wireless signals with a terminal are connected to the wireless repeater. The downlink signal from the base station to the terminal is received by the donor antenna and amplified in the wireless repeater and then transmitted to the terminal through the service antenna. The uplink signal from the terminal to the base station is received by the service antenna and amplified in the wireless repeater and then donor. It is delivered to the base station via an antenna.

Typically, these donor antennas and service antennas are directional, so it is ideal that the radio waves are radiated only in the direction the antenna is facing. However, in the case of the actual antenna, the radio wave is radiated not only in the direction in which the antenna is facing, but also partially radiated in the rear. At this time, the intensity of the radio wave radiated forward and the intensity of radio wave radiated backward is referred to as the front and rear ratio, the higher the front and rear ratio, that is, the stronger the strength of radio waves radiated to the front becomes an ideal antenna.

In the case of a wireless repeater, the donor antenna and the service antenna are directed in opposite directions, but since the transmit / receive frequencies of each antenna are the same, the signal transmitted from the service antenna (or the donor antenna) and the donor antenna (or service antenna) The frequency of the signal received by) is the same. Therefore, in the conventional wireless repeater, a signal transmitted from one antenna may be fed back to another antenna and input, thereby causing the repeater to oscillate, thereby making it impossible to operate normally. In order to prevent this, it is necessary to further improve the front and rear ratios of the donor antenna and the service antenna itself to improve the isolation between the two antennas (that is, the extent to which a plurality of adjacent antennas do not interfere with each other). However, even if the front-to-back ratio of the antenna itself is improved, the feedback signal cannot be completely removed. Therefore, research on a technology for removing a signal input once fed back into the wireless repeater has been conducted.

Conventional technology for removing the feedback signal once input into the wireless repeater is an interference cancellation system (Interference Cancellation System; ICS), Figure 1 schematically shows the combination of this conventional ICS module added to the wireless repeater and have. In the conventional ICS module, as shown in FIG. 1, a signal transmitted through one antenna is fed back to eliminate a signal input back to another antenna. To explain the principle briefly, a signal that is fed back to a receiving antenna and received from a wireless repeater Some internal coupling is used to find the antiphase of the signal.

The operation principle of the conventional ICS will be described in more detail with reference to FIG. 1 as follows. For convenience of description, the wireless signal is received from the first antenna 50, amplified in the wireless repeater circuit 10, and then transmitted through the second antenna 60. The signal received from the first antenna 50 is amplified by the wireless repeater circuit 10 after passing through the feeder 55 and the first directional coupler 20. The amplified signal is separated into two parts by the second directional coupler 30, part of which is transmitted via the feed line 65 and the second antenna 60, and part of which is input to the ICS module 40. A part of the signal transmitted through the second antenna 60 is fed back and re-entered into the wireless repeater circuit 10 through the first antenna 50. The delay filter 41 of the ICS module 40 delays a signal input through the directional coupler 30 by a delay time of the signal fed back and re-input so that both signals are simultaneously connected to the wireless repeater circuit. Enter (10). The signal delayed by the delay filter 41 is amplified by a phase-error amplifier 43 opposite to the original phase by 180 °. At this time, the controller 45 controls the phase error amplifier 43 according to the magnitude of the signal fed back and input so that the signal output from the ICS module 40 has the correct phase and size. Therefore, the signal fed back from the second antenna 60 and re-input to the wireless repeater circuit 10 is canceled by the ICS module 40 and canceled by the signal whose phase is inverted by 180 °.

As such, the conventional ICS module may greatly improve the isolation between the two antennas of the wireless repeater by removing the feedback signal. On the other hand, when transmitting a wireless signal through the antenna, not only the feedback signal as described above, but also a lot of interference due to the multi-path fading (multi-path fading) caused by the complex environment. However, although the isolation improvement by the conventional ICS module is very effective in the absence of the influence of the reflected wave, it is impossible to eliminate the interference of the reflected wave in the wireless environment in which there are many reflected waves due to the complex surrounding buildings. That is, the conventional technique can only remove the feedback signal directly input from the transmitting antenna, and cannot reflect the reflected wave reflected from another object. Therefore, there is a problem in that a wireless repeater having an ICS module as in the prior art cannot be used because it is less effective in urban areas.

The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide an interference cancellation antenna that can effectively improve the front and rear ratio even in a wireless environment in which reflected waves exist.

In addition, an object of the present invention is to provide a wireless repeater with improved performance by effectively removing not only the signal fed back from the transmitting antenna to the receiving antenna but also the reflected waves reflected from other objects without using a complicated ICS module. For the purpose of

1 shows a conventional wireless repeater including an ICS.

2 shows the structure of an antenna used in a conventional wireless repeater.

3 shows a structure of an antenna according to the present invention.

4 shows a structure of a wireless repeater using an antenna according to the present invention.

※ Explanation of code about main part of drawing ※

10 ....... Wireless repeater circuit 20,30 .... directional coupler

40 ............ Interference elimination system 41 ....... Delay filter

43 ....... Phase Error Amplifier 45 ....... Controller

50,60,100,120 .... antenna 55,65 .... feeder

58 ....... Reflector 53,103,104..Dipole element

110 ...... Directional Coupler

In order to achieve the above object, an interference cancellation antenna of the present invention includes a plurality of first dipole elements directed in a forward direction; A plurality of second dipole elements directed in a rearward direction; A feeder supplying a signal to be radiated into the air through the first and second dipole elements; And located between the feed line and the first and second dipole elements, to distribute signals supplied from the feed line to the first and second dipole elements, respectively, wherein a phase is applied to the signal distributed to the second dipole element. It characterized in that it comprises a directional coupler to reverse the 180 °.

In addition, the wireless repeater according to the present invention is characterized in that the donor antenna for transmitting and receiving with the base station and the service antenna for transmitting and receiving with the terminal as the interference cancellation antenna as described above.

Now, with reference to the accompanying drawings will be described in detail the principle of the present invention.

As described above, in the conventional wireless repeater that removes a feedback signal using an interference cancellation system (ICS) module, it is impossible to remove countless reflected waves reflected from a complex terrain. This is because the ICS module is intended to remove only signals fed directly from the antenna. Thus, in order to remove the interference due to the myriad of reflected waves at once, it is necessary to remove the reflected waves before they are input to the wireless repeater, unlike the conventional method of removing a signal already input to the wireless repeater. To this end, the present invention does not use the conventional ICS module, but uses a new type of antenna having a different structure from the conventional antenna. That is, the present invention eliminates interference due to reflected waves through the antenna, not the ICS module.

2 illustrates an antenna structure of a conventional wireless repeater. As shown in the side view of FIG. 2, the conventional antenna 50 is composed of a plurality of dipole elements 53, a feed line 55, and a reflector plate 58. Here, the dipole element 53 serves to radiate radio waves, and the feed line 55 serves to transmit a signal between the antenna 50 and the wireless repeater circuit. On the other hand, the reflector 58 disposed on the rear of the antenna serves to prevent the radiation of radio waves to the rear portion of the antenna. In the conventional antenna, the front and rear ratio of the antenna can be increased by only radiating the radio wave forward by the reflector 58, but the ICS module described above is not necessary because the radio wave is not completely blocked. In addition, the reflection plate 58 or the ICS module is less effective when there are reflection waves due to the complex terrain.

3 illustrates a new antenna structure of the wireless repeater according to the present invention. As shown in Figure 3, the new antenna 100 according to the present invention is a dual antenna structure consisting of a plurality of dipole elements 103 directed in the front direction and a plurality of dipole elements 104 directed in the rear direction, Together with the dual antenna, a feed line 105 and a directional coupler 110 for coupling a signal between the dipole elements 103 and 104 and the feed line 105. In this case, the directional coupler 110 serves to invert the phase 180 degrees with the original signal with respect to the signal transmitted to the dipole element 104 directed in the rear direction (ie, the "B" plane). That is, the radio waves radiated from the front dipole element 104 and the radio waves radiated from the rear dipole element 105 are 180 degrees out of phase with each other. Therefore, unlike the conventional antenna 50, the antenna 100 according to the present invention does not use a reflector 58 to prevent radio waves from radiating to the rear of the antenna, but rather radiates radio waves to the rear, but the phase difference is 180. It is to be °.

Looking at the principle that the effect of the interference due to the reflected wave in the wireless repeater consisting of the antenna according to the present invention is as follows. The signal to be amplified by the wireless repeater and radiated through the antenna 100 is transmitted to the feed line 105. The signal transmitted to the feed line 105 is distributed and supplied to the dipole antenna 103 of the "A" plane and the dipole antenna 104 of the "B" plane by the directional coupler 110, respectively. At this time, the signal supplied to the dipole antenna 104 of the "B" plane is an inverted phase signal inverted by 180 degrees and has a coupling value of 40 dB equal to the front and rear ratio of the antenna. Thus, according to the antenna structure of the present invention shown in Figure 3, when the original signal radiated through the dipole antenna 103 of the "A" plane is reflected by the surrounding environment to generate the interference wave, the "B" plane The signal radiated through the dipole antenna 104 will also be reflected by the surroundings, similar to the original signal radiated through the dipole antenna 103 on the "A" plane, to produce the same interference wave. However, since the signal transmitted from the "A" plane dipole antenna 103 and the signal transmitted from the "B" plane dipole antenna 104 are out of phase with each other, interference waves generated by the respective surroundings generated from the two antennas are They are canceled out.

Figure 4 schematically shows a wireless repeater using an antenna according to the present invention as described above. The wireless repeater uses the antenna shown in FIG. 3 as a donor antenna and a service antenna, respectively. The signal amplified by the wireless repeater is radiated not only in the forward direction but also in the backward direction. Since the signals in the two directions are reversed in phase, radio waves cancel each other in the rear region between the donor antenna and the service antenna. Therefore, the feedback signal and the interference signal which are re-entered into the wireless repeater can be reduced, thereby greatly improving the performance of the wireless repeater.

As described so far, according to the present invention, since the front and rear ratio of the antenna is very excellent, the isolation between the antennas of the wireless repeater can be greatly improved, and the restriction on the surrounding environment is greatly reduced when installing the wireless repeater. In addition, it is possible to provide a wireless repeater having a high gain in any environment. In addition, according to the present invention, there is no need to use the interference cancellation ICS module as compared to the conventional wireless repeater, there is an advantage that can be produced a high-performance wireless repeater at a lower cost.

Claims (3)

A plurality of first dipole elements directed in a forward direction; A plurality of second dipole elements directed in a rearward direction; A feeder supplying a signal to be radiated into the air through the first and second dipole elements; And Located between the feeder line and the first and second dipole elements, the signals supplied from the feeder line are distributed to the first and second dipole elements, respectively, wherein phases are applied to the signals distributed to the second dipole element. An interference cancellation antenna comprising a directional coupler to invert 180 °. The method of claim 1, And the output of the second dipole element of the directional coupler is about 40 dB. In the wireless repeater comprising a donor antenna for transmitting and receiving with the base station and a service antenna and amplification circuit for transmitting and receiving with the terminal, amplifying a radio signal between the base station and the terminal, The service antenna and donor antenna are respectively: A plurality of first dipole elements directed in a forward direction; A plurality of second dipole elements directed in a rearward direction; A feeder supplying a signal to be radiated into the air through the first and second dipole elements; And Located between the feeder line and the first and second dipole elements, the signals supplied from the feeder line are distributed to the first and second dipole elements, respectively, wherein phases are applied to the signals distributed to the second dipole element. A wireless repeater comprising a directional coupler to invert 180 °.