KR19990071228A - Cell site rf front end system using the antenna sharing for the different cellular telephone subscribers - Google Patents

Abstract

1. TECHNICAL FIELD OF THE INVENTION

Transceiver of a base station for accommodating heterogeneous mobile subscribers by sharing an antenna.

2. The technical problem to be solved by the invention

When the analog base station system and the digital base station system are installed in one base station, the antenna is to be configured using the minimum antenna and RF element.

3. Summary of Solution to Invention

First and second antennas, both transmitting and receiving; First and second duplexers coupled to the first and second antennas, respectively; A first linear amplifier amplifying a signal input from an analog channel card and providing the amplified signal to the first duplexer; A second linear amplifier amplifying a signal input from a digital channel card and providing the amplified signal to the second duplexer; First and second low noise amplifiers for amplifying a received signal input from the first and second duplexers, respectively; And first and second power dividers for distributing the received signals amplified by the first and second low noise amplifiers to an analog channel card and a digital channel card.

4. Important uses of the invention

Used for analog / digital sharing base stations.

Description

Transceiver of base station to accommodate heterogeneous mobile subscribers by sharing antenna

The present invention provides a base station transceiver for accommodating heterogeneous subscribers while reducing the number of antennas installed when a heterogeneous mobile communication base station system using the same frequency band, such as an analog method and a digital method, is installed in one base station. It is about.

The number of antennas of the mobile communication base station system is determined according to whether the duplex scheme is used, the reception spatial diversity scheme, and a base station configuration method such as omni-directional or sector base station. In the case of a typical analog mobile phone base station using the reception space diversity without using the duplex method, an omnidirectional base station using one omni-directional transmission antenna and two reception antennas, and a transmission antenna having a directional beam pattern characteristic 3 A three-sector base station using two dogs and six receive antennas is common. When the base station equipment of the digital mobile communication system is additionally installed in the analog mobile communication system, the number of antennas is doubled, making installation and maintenance very difficult.

1 and 2 show the structure of a radio frequency (RF) front end when a conventional analog (AMPS) and digital (CDMA) base station system is installed in one base station, and FIG. 1 is an RF front end of omni-directional base station equipment. Figure 2 shows the structure of Figure 2 shows the structure of the RF front end of the three-sector base station equipment.

In general, a base station system that accommodates conventional analog and digital schemes has a separate transmit and receive RF portion for each scheme.

Looking at the flow of the transmission signal in the conventional base station system, the signals generated from the channel card is combined through a power combiner and amplified by more than 40 dB by a linear power amplifier (LPA: 13), and amplified The signal is passed by only the signal in the range of 869 to 894 MHz by the transmission bandpass filter 12. The band-passed signal is radiated onto the free space through the transmission antenna 11.

This transmission signal flow is the same for both analog (AMPS) and digital (CDMA), which is achieved through separate RF stages.

On the other hand, the flow of the received signal, the signal received through the receiving antenna 14 is passed only the signal in the range of 824 ~ 849 MHz by the reception band pass filter 15. The band-passed signal is inputted to a low noise amplifier (LNA) 16 and amplified by about 40 dB or more and transmitted to the channel card. In the case of the receiving RF stage, since the spatial diversity is used, two sets (17 to 19) of these structures are required for each receiving path, and the flow of the received signal is the same for both the analog and digital methods.

When the analog and digital systems are installed in one base station, the equipment installed in the omni-directional base station includes two transmit antennas, four receive antennas, two transmit bandpass filters, four receive bandpass filters, and a linear power amplifier. It consists of two and four low noise amplifiers.

When the base station equipment is applied to the three-sector base station shown in Fig. 2, the equipment installed in one base station includes six transmission antennas, 12 reception antennas, 6 transmission bandpass filters, and 12 reception bandpass filters. It consists of six linear power amplifiers and twelve low-noise amplifiers. The total number of antennas in one base station is 18.

When the analog base station system and the digital base station system are installed in one base station, various methods have been proposed to reduce the number of antennas installed and simplify the structure.

First of all, as shown in FIG. 3, a duplexer is used to share a transmit / receive antenna for each analog and digital method.

In Fig. 1, the receiving antenna and the transmitting antenna are replaced with one transmitting / receiving antenna 31, and the transmitting filter and the receiving filter are replaced with one duplexer 32. In addition, each of the analog and digital methods is provided with one reception antenna 35, one reception bandpass filter 36, and one low noise amplifier 37 for reception diversity.

Looking at the flow of the transmission signal in the base station system, the signal generated in the channel card is combined through a combiner, the combined signals are amplified by more than about 40 dB by the linear power amplifier. Then, the amplified signal is band-passed only by the transmission filter portion of the duplexer 32 in the range of 869 to 894 MHz, and the band-passed signal is radiated in the free space through the transmitting and receiving antenna 31.

On the other hand, there are two flows of a received signal, one of which is a process of being received through a receive diversity antenna, and the other of which is a process of receiving through a dual transmit / receive antenna. Since the flow of the signal received through the receive diversity antenna is the same as the process described with reference to FIG. 1, it will be omitted. Only the flow of the signal received through the dual transmit / receive antenna 31 will be described.

The signal received through the dual transmit / receive antenna 31 is band-passed only by the receiving filter portion of the duplexer 32 in the range of 824-849 MHz, and amplified by about 40 dB or more by the low-noise amplifier 34 so as to provide a channel card. Is entered.

When the analog and digital base station system is installed in one base station using a duplexer as described above, the equipment provided can be combined with a transmitting antenna and one receiving antenna to form a single transmitting / receiving antenna, so that the omni-directional shared base station The number of antennas can be reduced from 6 to 4 cases and from 18 to 12 for a 3-sector shared base station.

However, in the case of the shared base station as described above, there is a problem that it is difficult to adjust the diversity effect because there is a lack of balance between the received signal passed through the duplexer and the signal received through the receive diversity antenna.

As another method of sharing the antenna, as shown in FIG. 4, the transmission of the two (AMPS / CDMA) systems is a method of jointly using the antenna in combination with transmission and reception.

Looking at the flow of the transmission signal in such a shared base station, the analog and digital signals are 2: 1 combined by the combiner 44 and amplified by the linear power amplifier 43. The signal amplified in this way is transmitted by only the signal in the range of 869 to 894 MHz by the transmission bandpass filter 42 and radiated in the free space through the transmission antenna 41.

On the other hand, the flow of the received signal, the signal received through the receiving antenna 45 is amplified by the low noise amplifier 47 by passing only the signal in the range of 824 ~ 849 MHz by the reception band pass filter 46. The amplified signal is then distributed to analog and digital channel cards via a 1: 2 power divider 48, respectively.

Using this sharing scheme, the number of antennas, linear power amplifiers, low noise amplifiers, and transmit and receive filters for omni-directional shared basestations ranges from 6 to 3, and from 18 to 9 for 3-sector shared basestations. Can be reduced.

However, in this case, the power to be transmitted is so large that a large load is placed on a linear power amplifier or a transmitting antenna, and the number of usable channels and power is practically limited.

Therefore, the present invention devised to solve the above problems of the prior art is an improved shared base station that can simultaneously solve the problems of the prior art while significantly reducing the number of antennas by using a duplexer and a power divider in combination The purpose is to provide a transceiver of the.

1 is an RF structure diagram of a conventional omni-directional analog and digital base station.

2 is an RF structure diagram of a conventional three-sector analog and digital base station.

3 is an RF structure diagram of an analog and digital base station having a dual transmit / receive antenna using a conventional duplexer.

4 is an RF structure diagram of an analog and digital base station sharing a conventional antenna.

5 is an RF structure diagram of an omni-directional analog and digital base station sharing an antenna according to the present invention.

6 is an RF structure diagram of a three-sector analog and digital base station sharing an antenna according to the present invention.

* Explanation of symbols for the main parts of the drawings

11, 41: transmitting antenna

12, 15, 18, 36, 42, 46: band pass filter

13, 33, 43, 53, 58: Linear Power Amplifier (LPA)

14, 17, 35, 45: receiving antenna

16, 19, 34, 37, 47, 54, 59: low noise amplifier (LNA)

31, 51, 56: dual transmit and receive antenna

32, 52, 57: duplexer

44: combiner

48, 55, 60: power divider

In order to achieve the above object, the present invention provides a transceiver of an omni-directional base station for sharing a base station by installing an analog base station and a digital base station system in one base station, the first and second antennas serving as both transmission and reception. ; First and second duplexers respectively coupled to the first and second antennas to perform filtering functions on the transmitted and received signals; A first linear amplifier amplifying a signal input from an analog channel card and providing the amplified signal to a transmission filter part of the first duplexer; A second linear amplifier amplifying a signal input from a digital channel card and providing the amplified signal to a transmission filter part of the second duplexer; First and second low noise amplifiers for amplifying a received signal input from the first and second duplexers, respectively; And first and second power dividers, each coupled to the first and second low noise amplifiers, to distribute the amplified received signal to an analog channel card and a digital channel card.

In addition, the transceiver of the three-sector type base station of the present invention for achieving the above object, the analog and digital base station system installed in one base station to the three-sector type base station transceiver for sharing the base station; The same sector for each sector, wherein the transmission and reception apparatus of one sector includes: first and second antennas, both transmitting and receiving, and having directionality and beam pattern characteristics; First and second duplexers respectively coupled to the first and second antennas to perform filtering functions on the transmitted and received signals; A first linear amplifier amplifying a signal input from an analog channel card and providing the amplified signal to a transmission filter part of the first duplexer; A second linear amplifier amplifying a signal input from a digital channel card and providing the amplified signal to a transmission filter part of the second duplexer; First and second low noise amplifiers for amplifying a received signal input from the first and second duplexers, respectively; And first and second power dividers, each coupled to the first and second low noise amplifiers, to distribute the amplified received signal to an analog channel card and a digital channel card.

Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. 5 and 6.

FIG. 5 is a diagram illustrating an RF stage that is a transceiver of an omni-directional analog / digital shared base station according to the present invention, in which 51 and 56 are dual transmit / receive antennas, 52 and 57 are duplexers, and 53 and 58 are linear power amplifiers. 59 denotes a low noise amplifier, and 55 and 60 denote power dividers, respectively.

The shared base station of the present invention uses only the two antennas using the duplexers 52 and 57 and the power dividers 55 and 60.

In the present invention, two sets of RF stages having the same configuration are provided.

The analog channel card is connected to the first linear power amplifier 53, and the digital channel card is connected to the second linear power amplifier 58. The first and second linear power amplifiers 53 and 58 are connected to the first duplexer 52 and the second duplexer 57, respectively. In addition, the first and second duplexers 52 and 57 are connected to the transmitting and receiving antennas 51 and 56, respectively. Meanwhile, for reception, the first and second low noise amplifiers 54 and 59 are connected to the first and second duplexers 52 and 57, respectively, and the first and second low noise amplifiers 54 and 59 are respectively output. The first and second power dividers 55 and 60 are connected respectively. Each of the power dividers 55 and 60 is connected to a receiving channel card of an analog (AMPS) and digital (CDMA) method.

Looking at the flow of the transmission signal in the shared base station of the present invention having the configuration as described above, the signal generated from the channel card is combined through a power combiner, the combined signal is about 40dB through the linear power amplifier (53, 58) Is amplified over. The amplified signal is band-passed only by the transmit filter portions of the duplexers 52 and 57 in the range of 869 to 894 MHz, and is radiated into free space through the transmitting and receiving antennas 51 and 56.

On the other hand, when looking at the flow of the received signal, the signal received through the transmitting and receiving antenna (51, 56) is band-passed only the signal within the range of 824 ~ 849 MHz by the receiving filter portion of the duplexer (52, 57), low noise amplifier It is amplified by about 40dB or more by (54, 59). The amplified signal is distributed by the power dividers 55 and 60 and input to the analog and digital channel cards, respectively.

In the shared base station of the present invention as described above, the two antennas are both transmitting and receiving, and the received signals separated through the duplexers 52 and 57 are divided into analog and digital receiving sides by the power dividers 55 and 60, respectively. . This solves the conventional problem of the diversity balance being broken by sharing only one reception among the diversity receptions with the duplexer.At the same time, both analog and digital transmissions are connected to one transmission antenna, so that a linear power amplifier and an antenna The conventional problem of increasing the capacity of is solved at the same time.

FIG. 6 is an example of applying the antenna sharing structure of the present invention to a three-sector sharing base station, and by reducing six antennas per sector to two, the total of 18 antennas can be reduced to six. In the case of a 3-sector shared base station, the structure and signal flow of the RF front end of each sector are the same as that of the omni-directional base station of FIG. 5, and only the antenna has an antenna having a directional beam pattern characteristic.

In order to apply the present invention to share a conventional analog and digital antenna, there are a few things to consider.

First, in the shared base station, the engineering of the digital and analog mobile telephone systems is the same, so there must be a premise that the coverage area, sector angle, horizontal beam width, and tilt are not different. If the antenna characteristics such as horizontal beam width are not the same, the proper antenna should be selected. Currently, antennas having horizontal beam widths of 120 degrees, 90 degrees, 83 degrees, and 60 degrees are mainly used as sector base station antennas. In the early stages of mobile communication, antennas having horizontal beam widths of 120 degrees are mainly used. Antennas having a horizontal beam width of 90 degrees or 83 degrees are mainly used. In the case of a base station in a large city where the base station density is high, a horizontal beam width of 60 degrees may be used. Sector base stations in suburban and small-town areas where there is not much traffic are best shared using antennas with 83- or 90-degree horizontal beamwidth, and 60- and 83-degree horizontally for sector base stations in large cities with high call volume. It would be appropriate to share using an antenna with a beamwidth.

After selecting the appropriate antenna, select a duplexer with the appropriate characteristics to minimize system degradation. The most important thing in determining the characteristics of the duplexer is to minimize the effect of the signal generated on the transmitting side on the receiving side. This can be divided into two cases. The first is to determine the reception band characteristics of the transmission filter to suppress the reception band noise generated by the linear amplifier on the transmitting side to the receiving side. The transmit band characteristic of the receive filter is determined to prevent the band signal from entering the receiver and saturating the receive low noise amplifier. This is because, when using a transmitting and receiving antenna separately, the signal separation as much as secured by the separation between antennas should be secured using a duplexer. In general, since the separation between the transmitting and receiving antennas is required in a mobile telephone system about 30 to 40 dB, a duplexer having a separation between the transmitting and receiving bands of about 40 dB or more should be used. In addition, it is necessary to minimize the insertion loss (within 0.5dB) to minimize the degradation of the reception sensitivity and the transmission output.

Finally, intermodulation is an important consideration in the application of the antenna sharing scheme. Among the intermodulation modes, passive mutual defenses caused by passive components must be considered when designing a structure for sharing antennas using a duplexer. Passive intermodulation at the antenna stage of a mobile telephone system occurs minutely due to the nonlinearity of the metal contacts at the antenna, feedline, duplexer, etc. However, as the transmission power increases and the number of channels increases, their intermodulation components may enter and affect the reception band. In a typical mobile telephone system, such manual intermodulation is regulated at around 160dBc @ 40W, so measurements should be made to verify that components such as connectors comply with these regulations. If the intermodulation components caused by a particular channel do not enter the reception band and fall below a specified level, use of that channel should be avoided. Therefore, it is most desirable to channel arrangement avoiding a channel that is likely to cause intermodulation.

As described above, the present invention can solve a problem of diversity balance by sharing only one reception among the diversity receptions with a duplexer, and at the same time, both analog and digital transmissions are connected to one transmission antenna, thereby providing linear power. Solving the problem that the capacity of the amplifier and antenna must be increased at the same time. Therefore, when the analog and digital base station systems are installed in one base station, the base station can be installed with a minimum number of antennas and RF elements, thereby reducing the installation cost and facilitating maintenance.

Claims (5)

In the transceiver of the omni-directional base station for sharing the base station by installing an analog base station and a digital base station system in one base station, First and second antennas, both transmitting and receiving; First and second duplexers respectively coupled to the first and second antennas to perform filtering functions on the transmitted and received signals; A first linear amplifier amplifying a signal input from an analog channel card and providing the amplified signal to a transmission filter part of the first duplexer; A second linear amplifier amplifying a signal input from a digital channel card and providing the amplified signal to a transmission filter part of the second duplexer; First and second low noise amplifiers for amplifying a received signal input from the first and second duplexers, respectively; And First and second power dividers, each coupled to the first and second low noise amplifiers, to distribute the amplified received signal to an analog channel card and a digital channel card. Transceiver of a base station having a. The method of claim 1, The duplexer transceiver of the base station, characterized in that the separation between the transmission and reception band is about 40dB or more. In the transceiver of the three-sector base station for sharing the base station by installing an analog base station and a digital base station system in one base station, Each sector is composed of the same configuration, the transceiver of one sector, First and second antennas, both transmitting and receiving, and having directional and beam pattern characteristics; First and second duplexers respectively coupled to the first and second antennas to perform filtering functions on the transmitted and received signals; A first linear amplifier amplifying a signal input from an analog channel card and providing the amplified signal to a transmission filter part of the first duplexer; A second linear amplifier amplifying a signal input from a digital channel card and providing the amplified signal to a transmission filter part of the second duplexer; First and second low noise amplifiers for amplifying a received signal input from the first and second duplexers, respectively; And First and second power dividers, each coupled to the first and second low noise amplifiers, to distribute the amplified received signal to an analog channel card and a digital channel card. Transceiver of the base station characterized in that it comprises a. The method of claim 3, wherein The duplexer transceiver of the base station, characterized in that the separation between the transmission and reception band is about 40dB or more. The method of claim 3, wherein The first and second antennas, Transceiver of a base station, characterized in that the antenna characteristics, such as the receiving area, sector angle, horizontal beam width, tilt (tilt) is the same antenna.