KR101715503B1 - Single band full duplex communication system using double balanced feed network circuit - Google Patents
Single band full duplex communication system using double balanced feed network circuit Download PDFInfo
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- KR101715503B1 KR101715503B1 KR1020150130495A KR20150130495A KR101715503B1 KR 101715503 B1 KR101715503 B1 KR 101715503B1 KR 1020150130495 A KR1020150130495 A KR 1020150130495A KR 20150130495 A KR20150130495 A KR 20150130495A KR 101715503 B1 KR101715503 B1 KR 101715503B1
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- signal
- feed network
- balanced feed
- coupler
- circulator
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
- H04B1/40—Circuits
- H04B1/54—Circuits using the same frequency for two directions of communication
- H04B1/58—Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa
- H04B1/583—Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa using a bridge network
- H04B1/585—Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa using a bridge network with automatic balancing
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B15/00—Suppression or limitation of noise or interference
- H04B15/02—Reducing interference from electric apparatus by means located at or near the interfering apparatus
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- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
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Abstract
Description
The present invention relates to a single-band full-duplex communication system, and more particularly to a single-band full-duplex communication system using a dual balanced feed-back network.
Recently, the use of small wireless terminal devices is increasing rapidly. These wireless communication devices use duplex communication to exchange information. Duplex communication is a communication method in which information is mutually exchanged while transmitting and receiving between devices.
Such full-duplex communication schemes include a time-division duplex (TDD) scheme and a frequency-division duplex (FDD) scheme, which are commonly used.
The TDD scheme performs full-duplex communication by separating the transmission interval and the reception interval in the time domain. The FDD scheme uses different frequency bands for transmission and reception.
However, in the case of the TDD scheme, a guard time interval is required between the transmission and the reception interval, and the frequency band is widened, and a specific frequency band can not be used for complete transmission or for complete reception. In the case of the FDD method, there is a disadvantage that the bandwidth is twice as much for transmission and reception.
In recent years, studies have been made on a single band full duplex system that improves the spectral efficiency by improving the disadvantages of the TDD and FDD methods.
Single-band full-duplex communication systems transmit and receive simultaneously in the same band. A single-band full-duplex communication system does not separate the transmission interval and the reception interval in the time domain, such as TDD, and therefore does not use the guard interval existing between the transmission and reception intervals and can use one band for complete transmission and reception The spectral efficiency is improved. Also, unlike the FDD scheme that uses the respective frequency bands for transmission and reception, the transmission efficiency is higher than that of the FDD scheme because the transmission and reception are performed in the same band.
However, since the single-band full-duplex communication system having the above advantages transmits / receives simultaneously in the same band, the transmission signal of the local station may cause interference to the receiver of the local station. The self interference signal generated by the local transmission signal generated in the single-band full-duplex communication system is much larger than the reception signal transmitted from the other station. Therefore, the received signal transmitted from the other station can be completely distorted by the magnetic interference signal.
If the received signal from the destination station is completely distorted, information on the destination station can not be obtained from the signal received from the destination station. Therefore, a single-band full-duplex communication system necessarily requires an additional process to effectively remove a magnetic interference signal that distorts a received signal transmitted from the other station.
A study on single-band full-duplex communication system is very important as one of many studies to improve the frequency use efficiency. A single-band full-duplex communication system can simultaneously transmit and receive in the same frequency band. In other words, this technique can improve the frequency efficiency by about two times.
However, there is a problem that a magnetic interference signal is generated in a single-band full-duplex communication system. The self interference signal indicates that the transmission signal of its own station is received by its own receiver. This phenomenon occurs because transmission and reception are performed simultaneously in the same frequency band. Since the magnitude of the magnetic interference signal is much larger than the signal transmitted from the other station, the signal transmitted from the other station can not be received unless the magnetic interference signal is removed. That is, the magnetic interference signal must be removed. Conventionally, there is a method of removing the magnetic interference signal in the RF region, but the effect of removing the magnetic interference signal is insufficient in the single-band full-duplex communication system.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a single-band full-duplex communication system using a dual balanced feed network in order to improve magnetic interference signal rejection performance.
The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.
In order to achieve the above object, according to the present invention, there is provided a single-band full-duplex communication system capable of simultaneously transmitting and receiving signals in the same frequency band, and a method of separating a transmission signal Tx transmitted from a transmitting terminal into a first signal and a second signal A first balanced feed network for receiving the first signal and for removing a self-interference signal, a second balancing feed network for receiving the second signal, A second balance feed network connected to the first balance feed network for communicating with the other station; a second balance feed network connected to the first balance feed network for changing the phase of the leakage signal leaked from the second balance feed network; And a leakage signal leaked from the first balancing feed network and a leakage signal transited from the phase shifter are combined and output to a receiving end And a binary (Combiner).
Wherein the first balancing feed network includes a first coupler for separating the first signal into two signals having a phase difference of 90 degrees, a signal rotated by 90 degrees out of the signals separated by the first coupler, A first circulator connected to the first port of the antenna for inputting a signal, a signal having no phase change among the signals separated by the first coupler, And a second coupler for outputting a combined signal from the first circulator and the second circulator.
At this time, the first port of the antenna may have a -90 degree feed and the second port may have a 0 degree feed.
A third coupler for separating the second signal into two signals having a phase difference of 90 degrees, a second balanced signal feeder for receiving a signal rotated by 90 degrees out of the signals separated by the third coupler, A third circulator for inputting a signal having no phase change among the signals separated by the third coupler and for connecting the input signal to the ground, And a fourth coupler for combining signals output from the third circulator and the fourth circulator.
The antenna may be implemented as a single patch antenna.
According to the present invention, a circuit is implemented using a dual balanced feed network structure in a single-band full-duplex communication system, whereby the magnetic interference signal cancellation performance is improved.
1 is a block diagram of a single-band full duplex communication system using a single antenna and balanced feed network.
2 is a circuit diagram of a single patch antenna and balanced feed network.
3 is a diagram showing a leakage path and a reflection path of a magnetic interference signal.
4 is a block diagram of an RF cancellation circuit in a single-band full duplex communication system using a dual balanced feed network in accordance with an embodiment of the present invention.
5 is a block diagram for simulating a conventional RF cancellation circuit and an RF cancellation circuit according to an embodiment of the present invention.
FIG. 6 is a graph showing a magnetic interference signal cancellation performance of an RF cancellation circuit using an existing balanced feed network.
FIG. 7 is a graph illustrating a magnetic interference signal cancellation performance of an RF cancellation circuit using a dual balanced feed network according to an embodiment of the present invention. Referring to FIG.
While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.
The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this application, the terms "use" or "having" are used to specify that there is a stated feature, figure, step, operation, element, part or combination thereof, and that one or more other features But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.
Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries are to be interpreted as having a meaning consistent with the contextual meaning of the related art and are to be interpreted in an ideal or overly formal sense unless expressly defined in the present application Do not.
In the following description of the present invention with reference to the accompanying drawings, the same components are denoted by the same reference numerals regardless of the reference numerals, and redundant explanations thereof will be omitted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.
The present invention relates to a single-band full duplex communication system capable of simultaneous transmission and reception in the same frequency band.
1 is a block diagram of a single-band full duplex communication system using a single antenna and balanced feed network.
Figure 1 shows a single-band full-duplex communication system using a conventional balanced feed network (BFN).
Referring to FIG. 1, a conventional single-band full-duplex communication system is a system in which a balanced feed network (BFN) is applied to further improve the performance of removing magnetic interference signals. This system uses a single antenna.
The
Basic RF cancellation consists of coupler, phase shift, attenuation, and combiner. It removes the self-interference signal basically. .
2 is a circuit diagram of a single patch antenna and balanced feed network.
2 shows an internal circuit diagram of a balanced feed network (BFN).
2, the
The Microstrip Lange Couplers (1, 2) divide the input signal equally. The divided signal has a phase difference of 90 degrees. In the Microstrip Lange Coupler (1, 2), a 90 degree phase shift occurs when the signal travels to the diagonal line.
3 is a diagram showing a leakage path and a reflection path of a magnetic interference signal.
3 (a) shows a path of a signal transmitted from the
The equation for the signal flow of the leakage path B can be expressed as follows.
Where V represents the voltage of the Tx signal input to the balanced feed network (BFN), and | L | represents the magnitude of leakage from the
The point where Leakage path A and Leakage path B meet is the output of Microstrip Lange Coupler (2), where signals from both paths are combined. At this time, the sum of the signals leaked to the receiver through each path is expressed by the following equation.
In Equation (7), it can be seen that the leaked signal in each circulator is removed from the output portion of the microstrip lange coupler (2).
3 (b) shows a path in which the transmission signal is reflected by the
The path through which the reflected signal flows to the receiver can be expressed as a reflection path A and a reflection path B. [ The reflected signals flowing through the two paths are also equal in magnitude and opposite in phase to each other and removed from the output of the Microstrip Lange Coupler (2).
The Tx signal having passed through the
In FIG. 2, the signal passed through the
The magnetic interference signal leaking to the receiver in the structure having the
4 is a block diagram of an RF cancellation circuit in a single-band full duplex communication system using a dual balanced feed network in accordance with an embodiment of the present invention.
The RF cancellation method proposed in the present invention uses a balanced feed network (BFN) in two stages to improve magnetic interference signal cancellation performance.
The circuit of the first
Referring to the flow of the transmission signal as a whole, the transmission signal is divided by a
When a transmission signal is applied to the
The leakage signal of the second
The
The
The first
The second
The
The
The
In one embodiment of the present invention, the first
In an embodiment of the present invention, the first port of the
In one embodiment of the present invention, the second
5 is a block diagram for simulating a conventional RF cancellation circuit and an RF cancellation circuit according to an embodiment of the present invention.
In order to compare and analyze the magnetic interference signal removing performance of the RF elimination circuit using the dual balanced feed network proposed in the present invention, a simulation circuit as shown in FIGS. 5A and 5B was constructed.
5 (a) is a block diagram of a simulation program for analyzing RF removal performance using a conventional balanced feed network. A transmission signal is applied to the terminal 1, and the magnitude of the magnetic interference signal is measured at the
5 (b) is a block diagram of a simulation program for analyzing the performance of the RF elimination method using the dual balanced feed network circuit proposed in the present invention. A transmission signal is applied to the
FIG. 6 is a graph showing a magnetic interference signal cancellation performance of an RF cancellation circuit using an existing balanced feed network.
Referring to FIG. 6, it can be seen that the magnitude of a signal traveling from terminal 1 to
FIG. 7 is a graph illustrating a magnetic interference signal cancellation performance of an RF cancellation circuit using a dual balanced feed network according to an embodiment of the present invention. Referring to FIG.
FIG. 7 shows the magnitude of a signal traveling from the
Referring to FIG. 7, it can be seen that the performance of removing the magnetic interference signal at about 2.45 GHz in which the system operates is about 72 dB. That is, it can be seen that the magnetic interference signal cancellation circuit using the double balanced feed network proposed by the present invention improves the magnetic interference signal cancellation performance of about 25 dB compared to the circuit using the conventional balanced feed network.
While the present invention has been described with reference to several preferred embodiments, these embodiments are illustrative and not restrictive. It will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention and the scope of the appended claims.
120
140 second
Claims (5)
A coupler for separating the transmission signal Tx transmitted from the transmitting end into a first signal and a second signal;
A first balanced feed network for receiving the first signal and removing a self-interference signal;
A second balanced feed network for receiving said second signal and for removing magnetic interference signals not removed from said first balanced feed network;
An antenna connected to the first balanced feed network for communicating with a partner station;
A phase shifter for shifting a phase of a leakage signal leaked from the second balanced feed network; And
And a combiner for combining a leakage signal leaked from the first balanced feed network and a leakage signal shifted by the phase shifter to a receiving end.
Wherein the first balanced feed network comprises:
A first coupler for separating the first signal into two signals having a phase difference of 90 degrees;
A first circulator for inputting a signal rotated by 90 degrees out of the signals separated by the first coupler and connecting the input signal to a first port of the antenna;
A second circulator for inputting a signal having no phase change among signals separated by the first coupler and connecting the input signal to a second port of the antenna; And
And a second coupler for combining signals output from the first circulator and the second circulator,
Wherein the single-band full-duplex communication system comprises:
Wherein the first port of the antenna has a -90 degree feed and the second port has a zero degree feed.
Wherein the second balanced feed network comprises:
A third coupler for separating the second signal into two signals having a phase difference of 90 degrees;
A third circulator for inputting a signal rotated by 90 degrees out of the signals separated by the third coupler and for connecting the input signal to the ground;
A fourth circulator for inputting a signal having no phase change among the signals separated by the third coupler and connecting the input signal to ground; And
And a fourth coupler for outputting signals output from the third circulator and the fourth circulator,
Wherein the single-band full-duplex communication system comprises:
Wherein the antenna is a single patch antenna.
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| KR1020150130495A KR101715503B1 (en) | 2015-09-15 | 2015-09-15 | Single band full duplex communication system using double balanced feed network circuit |
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Cited By (2)
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| US10951259B2 (en) | 2017-10-30 | 2021-03-16 | Electronics And Telecommunications Research Institute | Method for simultaneously transmitting/receiving upstream and downstream signals using remote PHY architecture and apparatus for the same |
| CN113708070A (en) * | 2021-08-26 | 2021-11-26 | 深圳大学 | Broadband single-station common-horizontal-polarization full-duplex antenna based on integrated beam forming network |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
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| US10951259B2 (en) | 2017-10-30 | 2021-03-16 | Electronics And Telecommunications Research Institute | Method for simultaneously transmitting/receiving upstream and downstream signals using remote PHY architecture and apparatus for the same |
| CN113708070A (en) * | 2021-08-26 | 2021-11-26 | 深圳大学 | Broadband single-station common-horizontal-polarization full-duplex antenna based on integrated beam forming network |
| CN113708070B (en) * | 2021-08-26 | 2022-03-15 | 深圳大学 | Broadband single-station common-horizontal-polarization full-duplex antenna based on integrated beam forming network |
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