JP2011151819A - Method of reducing number of feeders in antenna diversity system, apparatus, base station, and base station site - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method, an apparatus, and a system to reduce the number of feeders for an antenna diversity constitution to receive a plurality of RF signals at the same frequency as that in a radio base station. <P>SOLUTION: In a tower-mounted amplifier 35, the individual RF signals from some or all of a plurality of antennas 10, 11, 12, 13 are converted in frequency into signals of intermediate frequency (IF) different with each other, and these signals are combined for transfer to a radio base station 1 with a smaller number of feeders 2. The combined signal is divided to individual signals in the radio base station 1, and the IF signals are converted in frequency into signals appropriate for a diversity process. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a tower-mounted amplifier (TMA) and antenna diversity. In particular, the present invention relates to a method and configuration for reducing the number of feeders from an antenna diversity system to a radio base station.

  Antenna diversity is used to improve reception (or transmission) of transmitted radio signals. There are many types of diversity, for example, time diversity, space diversity, deflection diversity, or combinations thereof. Spatial diversity and deflection diversity reduce the effects of fading of the received radio signal.

The antenna diversity system is constructed at a distance from each other or has at least two antennas with different deflections. In the case of receive diversity , a signal (RX signal) from a remote transmitter is received by two or more antennas. In the case of transmission diversity , a transmission signal (TX signal) is transmitted by two or more transmission antennas connected to a transmitter . Hereinafter, the diversity antenna is referred to as a diversity antenna. By connecting the duplex filter to the antenna, transmission and reception can be performed using the same antenna. The duplex filter separates the TX and RX signals from each other. The signal is transferred by the feeder between the antenna and the transceiver (TRX). In prior art diversity configurations, the feeder and its associated antenna are referred to as a diversity branch or simply a branch. In the present invention, the diversity branch includes a diversity antenna and a device through which a signal received by the antenna passes.

  Next, consider diversity related to reception. The RX signal from the diversity antenna is subjected to diversity processing to obtain an improved (enhanced) signal. Diversity processing may be, for example, selecting the strongest antenna signal, or may add multiple signals and further process the resulting signal.

  Each RF signal received in the diversity antenna configuration is connected to each tower-mounted amplifier (TMA), and the amplified signal from each amplifier includes an individual feeder connected to a radio base station transceiver (TRX). Is transferred in the diversity branch. The feeder is usually a coaxial cable. Some branches are connected to one TRX. The TRX may be provided with a diversity branch for modulation and diversity signal processing.

  Tower mounted units are often referred to as mast head amplifiers. Note that these units do not need to be installed on the tower, and may be installed on pillars, building walls, the roof of the building, and the like. The same is true for diversity antennas. Therefore, the present invention is not limited to the amplifier installed in the tower. A tower mounted amplifier (TMA) is just a name, and by its name, this type of equipment is known to those skilled in the art.

1, the radio base station and (RBS) 1, discloses a conventional site and a rolled Biteiru feeder 2-5 between the wireless base station and TMA6～9. Each TMA is connected to each diversity antenna 10-13. These TMA's are all identical and therefore only the TMA 6 is referred to in the following description. The antenna 10 is connected to a duplex filter 14 having a transmission unit (TX) 15 and a reception unit (RX) 16. The RF amplifier 17 amplifies the filtered received (RX) signal and supplies it to another duplex filter 18 having a transmitter (TX) 19 and a receiver (RX) 20. The function of the duplex filter is to separate the TX signal from the RX signal and prevent the TX signal from leaking into the reception chain 21. The signals received by the antennas 10, 11, 12, and 13 and processed by the TMAs 6, 7, 8, and 9, respectively, are supplied to the diversity branches A, B, C, and D, respectively.

  The radio base station 1 includes one duplex filter 22 to 25 and one low noise amplifier (LNA) 26 to 29 corresponding to each TMA. The core of a radio base station is a transceiver (TRX) 30, 31 (TRX1, TRX2). Depending on its capabilities, the transceiver has a traffic capacity designed for that radio base station. for that reason. There may be one TRX, or there may be two or more illustrated transceivers.

  The configuration shown in FIG. 1 is called four-way diversity with four feeders.

FIG. 2 shows a frequency spectrum illustrating the frequency range that can pass through the RX filter 22, which is the RX full band 32 assigned to the service. The radio channel on which the RX signal for the transceiver is received and the TX signal is transmitted from that same transceiver is called the user channel. Since two transceivers are shown in FIG. 2, there are two user channels. Each of these channels is shown as a small rectangle. The frequency band that the user channel occupies is called the user band, which is shown in parentheses 33. In each of the four branches there is a respective user band, which is the same in all branches (expressed in kHz). However, the feeder can transfer signals at all frequencies a RX entire band 32 until including several GHz. Therefore, the feeder of each branch is used with low efficiency.

In principle, one TRX is sufficient to diversity process four RX signals to obtain an enhanced RX signal. However, radio base stations are designed to handle large traffic capacities and also have many TRXs for security reasons. For this reason, the output of each LNA is connected to all transceivers of the radio base station, as indicated by a number of arrows and collectively as 34.

  Patent Document 1 discloses a base station including an antenna diversity system connected to a multi-coupler, and an antenna signal is fed from each multi-coupler to each receiver using individual feeders.

US Pat. No. 6,505,041

The disadvantage of the prior art is that each branch requires a dedicated feeder. Thus, a diversity antenna with many antennas requires as many feeders as there are antennas. The feeder is expensive. Also, the feeder is heavy. The antenna is not so expensive. Therefore, a system with many diversity antennas is very expensive from an economic point of view, although it is beneficial from a reception quality point of view.

The object of the present invention is to provide a method, device, radio base station and system according to claims 1, 7, 11 and 12 with a reduced number of feeders compared to the prior art.

Salient features of the invention, one moves / frequency conversion RX signal received by the diversity antenna unused to frequency, the frequency converted signal integrated / combined with the RX signal is not subjected to frequency conversion, The resultant synthesized signal is transferred to the radio base station by one feeder.

  Depending on the radio system in which the present invention is used, the meaning of “frequency” and “signal frequency” may be different. The preferred embodiment of the present invention is a cellular mobile radio system such as WCDMA, GSM, AMPS, NMT. The bandwidth of WCDMA is 5 MHz, GSM is 200 kHz, AMPS is 30 kHz, and NMT is 25 kHz. It is a signal with each bandwidth that is frequency converted to another unused part of the frequency band (by RBS). In WCDMA, a 5 MHz signal includes at least one of voice and data from a plurality of users. In a GSM system, a 200 kHz signal includes at least one of voice and data from a maximum of eight users. In AMPS and NMT, signals of 30 kHz and 25 kHz respectively include at least one of voice and data from one user. Therefore, the signal frequency is actually a frequency band.

1 is a block diagram of a prior art 4-way diversity system. FIG. It is a figure which shows the frequency illustrated with the diversity system of the prior art of FIG. 1 is a block diagram showing a first embodiment of a 4-way diversity system according to the present invention. FIG. It is a figure which shows the frequency illustrated in the 1st Example. It is a block diagram which shows the 2nd Example of the 4-way diversity system according to this invention. It is a figure which shows the frequency illustrated in the 2nd Example. It is a block diagram showing a third embodiment. It is a figure which shows the frequency illustrated in the 3rd Example. It is a figure which shows the modification of a 1st Example. It is a figure which shows the frequency relevant to the modification of FIG. It is a block diagram which shows the 4th Example of this invention. It is a figure which shows the frequency illustrated in the 4th Example. It is a block diagram which shows the 5th Example which has the frequency conversion unit isolate | separated. It is a figure which shows the frequency relevant to the frequency conversion unit.

FIG. 3 illustrates an embodiment of the present invention. Elements similar to those in FIGS. 1 and 2 are given the same reference numerals. Tower-mounted amplifier 35 of the new has a frequency converter 36, 37, 38, respectively are connected to the antenna 11, 12, 13, the frequency of the received RF antenna signal, the RF antenna signal to a predetermined frequency The reference signals f1, f2, and f3 are mixed to move to an unused frequency. The signal received by the antenna 10 has no frequency shift. The reference signal may be a continuous wave signal, a CW signal, a signal from a local oscillator, or the like.

  The reference signal does not occupy the frequency band. Therefore, the above signal definition does not apply to the reference signal. A frequency converter is a device that receives an RX antenna signal as an input and mixes it with a reference signal to obtain a signal that has been frequency converted to an intermediate frequency (IF). The output of each frequency converter is connected to each bandpass filter IF1, IF2, IF3. The unconverted original radio signal received and amplified by the antenna 10 in the diversity branch A and the IF signals in the branches B, C, and D are input to the combiner 39, and these signals are combined. The combined signal is sent to the bandpass filter RX 2 in the duplex filter 18. The duplex filter is connected to the feeder 2. Therefore, the combined signal including the signals in the diversity branches A to D is transferred to the radio base station 1 by a single feeder.

  The filter IF1 prevents the signals from the converters 37 and 38 from leaking to the diversity branch B. The filters IF2 and IF3 have the same function.

  FIG. 4 relates to FIG. 3 and is a frequency spectrum illustrating signals at different locations in the TMA and the feeder. The user band is indicated by 33 and the three intermediate frequencies are indicated by 40, 41 and 42. At this time, the feeder is used at an efficiency three times that provided by the prior art configuration shown in FIGS.

In the illustrated embodiment, the received radio signal is upconverted to an IF frequency higher than the user band 33 . The IF frequencies are different from each other, i.e. the three IF signals at the output of the frequency converter are at different IF frequencies.

The range of frequencies that have passed through the filter RX1 is indicated at 43. The range of frequencies that have passed through the filter RX2 is shown in the entire RX band. Note that the IF frequency must be in the unused portion of the entire RX band. In the illustrated embodiment, the upconverted IF signal is to the right of the frequency range 43 that has passed through the filter RX1. If the frequency range 43 is further to the right, as shown by the dashed bracket 44 in FIG. 4, the IF signal should be to the left of the bracket range and not interfere with the user band 33. is there. Accordingly, RX signal is down-converted to a lower band of the IF from the User chromatography THE band 33. There may be situations where the IF signal is on either side of the user band.

  The configuration of FIG. 3 provides 4-way diversity with one feeder.

In the radio base station, the signal carried by the feeder passes through the duplex filter 22 and the low noise amplifier 26 and is input to the transceiver 30. In that transceiver, the signal is divided into four RX chains. Signals related to diversity branches B, C, and D are frequency-converted. Diversity processing is performed on each signal of the diversity branches A to D. Diversity processing may be performed by a diversity receiver.

  The configuration shown in FIG. 5 is similar to that of FIG. 3, but at this time, the tower-mounted amplifier 45 has only one frequency converter 36. In the combiner 39, the original signal in the diversity branch 39 is combined with the IF signal in the branch B to be a combined signal, and this combined signal is transferred to the radio base station by the single feeder 2. This configuration provides 2-way diversity with one feeder. The frequency spectrum in the single feeder 2 is shown in FIG.

A configuration for providing 4-way diversity with two feeders is shown in FIG. This configuration is obtained by doubling the configuration shown in FIG. 5 and uses two TMA45. Feeders 2 and 4 from the two TMAs are connected to each duplex filter of the radio base station. As mentioned above, in principle it is possible to use only one TRX, but in practice a radio base station has multiple transceivers. It should be understood that the feeders 2 and 4 carry the same intermediate frequencies 40 to 42 as the same two user bands 33. Accordingly, illustration of the frequency shown in FIG. 8 is the same for the two feeders.

  The advantages of embodiments using TMA in which the direct antenna signal is integrated with the IF signal and the resulting composite signal is transferred to the radio base station with a single feeder is the modification of existing radio base stations There is no need. This is because those base stations already have a frequency converter, and the converter converts the IF signal + direct antenna signal into a second IF signal.

By using the construction according to the present invention, the diversity antenna and the number of feeders have, in comparison with the conventional configuration in which the diversity signals are transferred in a dedicated feeder, fewer feeder in diversity signal radio base station To be transferred to.

FIG. 9 shows a modification of the embodiment shown in FIG. Here, all antenna signals are frequency converted. An additional frequency converter 46 is used, which is inserted into the diversity branch A of the antenna 10. In this embodiment, four IF signals are integrated into a combined signal, and the combined signal is transferred to the radio base station by a single feeder 2. This provides 4 way diversity with 1 feeder. In this embodiment, the radio base station has only one duplex filter, one low noise amplifier, and one transceiver (not shown). Since only one transceiver is used, only one user channel is used in the user band, and therefore the two rectangles are not shown in the frequency diagram of FIG. In this embodiment, the signal passing through the filter RX1 may be at a level of several GHz (10 ⁹ ) and the IF signal on the feeder may be at a level of several tens of MHz (10 ⁷ ). The frequencies f1 to f4 of the reference signal are in the frequency range between them.

  A variation of the configuration shown in FIGS. 5 and 7 is to frequency convert all diversity antenna signals and use an additional frequency converter similar to the frequency converter 46 in the embodiment of FIG. .

  In FIG. 11, the RX signals of the antennas 11, 12, and 13 are subjected to the first frequency conversion by the frequency converters 36, 37, and 38 connected to the filters IF1, IF2, and IF3 (f1, f2, and f3 are The same frequency can be used, but in that case f5, f6, f7 must have different frequencies). However, the RX signal at antenna 10 is not subjected to any frequency conversion by TMA. The embodiment of FIG. 11 is characterized in that the frequency-converted IF signals at the outputs of the filters IF1, IF2, IF3 mix these IF signals with the second set of reference signals f5, f6, f7, and the frequency converter Filtering the resulting signals in IF filters RX3, RX4, RX5 connected to 47, 48, 49, so that a second frequency conversion is performed in the frequency converters 47, 48, 49. . The direct original antenna signal passes through the filter RX1 of the duplex filter 14, the low noise amplifier 17, and a second filter RX1 similar to the filter RX1 of the duplex 14, and from the outputs of the filters RX3 to RX5 at the combiner 39. Are combined with the frequency-converted signal. The combined signal of all diversity branches is transferred to the radio base station by a single feeder 2.

  The reference signals f5 to f7 are at frequencies such as those shown in parenthesis 50 where the signals at the outputs of filters RX3 to RX5 are adjacent to the frequency of the filtered direct signal shown in parentheses 51 in FIG. Selected to be. This embodiment enables the use of SAW (surface acoustic wave) filters IF1 to IF4 with sharp characteristics and accurate passband frequencies.

FIG. 13 shows an embodiment having a frequency conversion unit 52 connected between the tower-mounted amplifier 35 and the radio base station 1. The frequency conversion unit is used in conjunction with a radio base station, the radio base station frequency-converts the divided signal to one same frequency, and a sufficient number to prepare for the diversity processing of the divided signal. Does not have a frequency converter.

In FIG. 13, TMA 35 is similar to that shown in FIG. 9, but the notation used for the filter and reference frequency is different. A composite signal having IF signals at different IF frequencies is fed to the frequency conversion unit 52 by a single feeder 2.

The frequency conversion unit 52 includes a duplex filter 53 including a filter TX and a filter 54 (RX2 to 5). The duplex filter is connected to frequency converters 55 to 58, of which frequency converter 55 is connected to duplex filter 59, and frequency converters 56 to 58 are connected to filters 60 to 62, respectively. The RX filter of the duplex filter 59 and the filters 60 to 62 are all similar to the filter RX1 of the TMA 35. The reference signals f5 to f8 are selected so that the resulting frequency converted signals at the outputs of the frequency converters 55 to 58 are all at the same frequency. These filtered and frequency converted signals appear at the output of the frequency conversion unit and they are adapted for diversity processing.

  The frequency of the signal appearing in the feeder and frequency conversion unit 52 is shown in FIG. The frequency of the synthesized signal in the feeder 2 is the same as that shown in FIG. In addition, the RX1 signal in the figure has shown the four output signals from a frequency conversion unit.

  Although not shown, it should be understood that a noise reduction filter (not shown) is inserted after the low noise amplifier 17 of the diversity branch A, that is, the branch carrying the original non-frequency converted RX signal.

  In many of the above embodiments of the present invention, if the filters RX2 to RX5 at the output of the frequency converter prevent each signal from leaking to the adjacent diversity branch, the filters RX2 and RX2 to 5 are each omitted. Also good.

Claims (16)

In a method of reducing the number of feeders between a radio base station (1) and a diversity antenna having at least two antennas (10-13) each adapted to receive individual RF signals, all of the same frequency There,
Converting one or more receive antenna signals into a corresponding number of IF (intermediate frequency) signals by mixing with a first set of corresponding numbers of reference signals (f1-f4);
One of the IF signals is transferred to the radio base station by a small number of feeders (2, 4) together with at least one of the original antenna signal and other converted IF signals without conversion. A method characterized by that. The diversity antenna has n antennas (n is an integer),
Convert all receive antenna signals except one to IF signals,
Transfer the unconverted antenna signal together with all IF signals to the radio base station with a single feeder,
The method of claim 1, comprising n-way diversity with one (single) feeder. The diversity antenna has n antennas (n is an integer),
Convert all receive antenna signals,
Forward all the receive antenna signals to the radio base station with a single feeder;
The method of claim 1, comprising n-way diversity with one (single) feeder.   By mixing the IF signal with a second set of reference signals (f5-f7), the IF signal is converted to a second IF frequency and transferred with a small number of feeders. The method of claim 1, wherein: The diversity antenna has a first antenna (10) and a second antenna (11);
Converting an antenna signal in the second antenna into an IF signal;
Transferring the IF signal to the radio base station with a single feeder (2) together with the unconverted antenna signal at the first antenna;
The method according to claim 1, comprising two-way diversity with one (single) feeder. The diversity antenna has a first antenna (10), a second antenna (11), a third antenna (12), and a fourth antenna (13),
Converting the RF signals from the second antenna and from the fourth antenna into first and second IF signals, both having the same intermediate frequency;
Transferring the unconverted antenna signal in the first antenna to the radio base station together with the first IF signal of the first feeder;
Transferring the unconverted antenna signal in the third antenna to the radio base station together with the second IF signal of the second feeder;
2. A method according to claim 1, characterized in that it comprises 4-way diversity with two feeders (2, 4). In the radio base station, by mixing the plurality of IF signals with a set of a plurality of reference signals (f5-f8), the plurality of IF signals are all converted into other IF signals having the same intermediate frequency,
6. The method according to claim 1, wherein diversity signal processing is performed on a signal frequency-converted twice at a common intermediate frequency. Equipment for reducing the number of feeders between a radio base station (1) and a diversity antenna having at least two diversity antennas (10-13) each adapted to receive individual RF signals each having the same frequency Because
One or more frequency transforms, each adapted to transform each antenna signal into a corresponding intermediate frequency signal (IF signal) by mixing with a predetermined reference signal (f1, f2, f3 or f4) Vessel (36-38),
One of the IF signals is combined with at least one of an unconverted antenna signal and another IF signal to form a composite signal that is transferred to the radio base station with a small number of feeders (2, 4). A device comprising a combiner (39).   9. The received (RX) signal from the diversity antenna follows the diversity branch (AD), and each diversity branch except one branch includes a frequency converter (36-38). Equipment.   9. An apparatus according to claim 8, characterized in that the received (RX) signal from the diversity antenna follows the diversity branch (AD) and each diversity branch comprises a frequency converter (46, 36-38).   A second set of frequency converters (47) adapted to convert a first set of IF signals into a second set of IF signals and forward them to the radio base station with a small number of feeders (2, 4). The device of claim 7, further comprising: -49). There are two diversity antennas (10, 11)
One of the two antennas is connected to a first duplex filter (14) and provided for transmission and reception;
A single frequency converter (36) for converting the antenna signal from the second antenna (11) to an intermediate frequency to form an IF signal;
The combiner (39) combines the original received (RX) signal from the first antenna (10) with the IF signal to generate a combined signal;
And a single feeder (2) for transferring the combined signal to the radio base station,
9. Device according to claim 7 or 8, characterized in that the one (single) feeder (2) comprises 2-way diversity. Duplicating the equipment, comprising equipment with four antennas (10-13) and two feeders (2, 4),
The apparatus according to claim 9, wherein two feeders are provided with 4-way diversity. A frequency conversion device used by being provided with at least one feeder (2) for transferring a plurality of signals at mutually different frequencies,
A frequency converter comprising a plurality of corresponding frequency converters (55-58) for converting the plurality of signals into a corresponding number of signals at the same frequency (RX1). A transceiver (TRX) with a plurality of frequency converters adapted to provide a plurality of frequency conversion signals called diversity signals all at the same frequency, and signal processing the diversity signal to obtain an improved signal A radio base station having the following means:
One feeder connected to the input of the transceiver and at least one intermediate frequency signal (IF signal) together with at least one of a non-frequency converted RF antenna signal and other converted IF signals. And a base station for supplying the diversity signal to each of the plurality of frequency converters to provide the diversity signal. A radio base station (RBS), at least one tower-mounted unit (TMA) comprising a filter (14) and an RF amplifier (17), at least two antennas (10-13) with diversity, It has at least one feeder (2, 4) that extends between the TMA and the RBS and exchanges received (RX) and transmitted (TX) signals, all signals received by the antenna being the same A radio base station system that is an RF signal of a reception (RX) frequency,
At least one frequency converter (36-38) provided in the TMA and connected to one of the plurality of diversity antennas for converting an RF signal of the antenna into an IF signal of an unused frequency;
A combiner (39) for combining with the IF signal and / or an unconverted RF antenna signal and / or another converted IF signal to generate a composite signal applied to the feeder; A radio base station system characterized by reducing the number of feeders.

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