RU2355079C2 - Antenna spacing system - Google Patents

Abstract

FIELD: physics; radio.

SUBSTANCE: present invention relates to amplifiers fitted on a mast (TMA) and antenna spacing. More specifically, the invention pertains to the method and device for reducing the number of feeders from an antenna spacing system to a wireless communication base station. Between wireless communication base station (1) and a device of spaced receiver antennae (RX), which has at least two spatially spaced antennae (10-13), each antennae is meant for receiving separate radio frequency signals (RF). All RF signals have the same frequency. The method is distinguished by that, one or more signals received by the antennae is converted in accordance with the number of signals with intermediate frequency (IF) through mixing with the first set of the corresponding number of reference signals (f1-f4). Signals received by all antennae are combined. One or more of these signals undergoes frequency conversion so as to generate a composite signal, which is transmitted to the wireless communication base station on single feeder (2, 4).

EFFECT: reduced number of feeders, while retaining quality of communication.

16 cl, 14 dwg

Description

FIELD OF THE INVENTION

The invention generally relates to mast mounted amplifiers (TMAs) and antenna diversity. More specifically, the invention relates to a method and apparatus for reducing the number of feeders from an antenna diversity system to a radio base station.

DESCRIPTION OF THE PRIOR ART

Antenna diversity is used to improve the reception (or transmission) of transmitted radio signals. Various types of diversity are known, such as temporal diversity, spatial diversity, polarization diversity, and combinations thereof. Spatial and polarization diversity reduces the fading effects of received radio signals.

The antenna diversity device comprises at least two antennas mounted at a distance from each other or having different polarizations. In the case of diversity reception, a signal (RX (receiver) signal) from a remote transmitter is received on two or more antennas.

In the case of transmit diversity, the transmission signal (TX (transmitter) signal) is transmitted by two or more transmit antennas to which the transmitter is connected. In the following description of antennas, diversity devices are referred to as diversity antennas. You can send and receive to the same antenna by connecting a duplex filter to the antenna, which separates the TX and RX signals from each other. Signals are transmitted between the antenna and the transceiver (TRX) via a feeder. In prior art diversity devices, the feeder and its associated antenna are referred to as a receive diversity branch (channel) or simply a branch. In the context of the present invention, the diversity branch comprises a diversity antenna and devices through which a signal received at that antenna passes.

The following describes the diversity in connection with the reception. RX signals from diversity antennas undergo diversity processing to obtain an improved signal. Diversity processing may, for example, consist in selecting the antenna signal that is most intense, or summing the signals and then processing the resulting signal.

Each RX signal received at the diversity antenna device is associated with respective mast-mounted amplifiers (TMAs), from which the amplified signal is transmitted to an individual diversity branch containing a feeder, typically a coaxial cable that is connected to the TRX transceiver in a radio base station (radio base station) ) Several branches are connected to one TRX transceiver, which can be equipped with a diversity receiver for demodulating and processing the diversity signal.

A mast-mounted unit is sometimes called a mast preamplifier (antenna amplifier). It should be noted that these blocks are not required to be installed on the mast, but can be installed on supports, walls of buildings, roofs of buildings, etc. The same is true for diversity antennas. The invention, therefore, is not limited to amplifiers mounted on masts. A mast mounted amplifier (TMA) is just the name by which a device of this kind is known to a person skilled in the art.

Figure 1 presents the corresponding prior art communication node containing a radio base station (RBS) 1, feeders 2-5 passing between the radio base station and several TMA amplifiers 6-9. Each TMA is connected to a corresponding diversity antenna 10-13. All TMAs are the same, and therefore only TMA 6 is mentioned below. Antenna 10 is connected to a duplex filter 14 containing a transmitting part (TX) 15 and a receiving part (RX) 16. An radio frequency (RF) amplifier 17 amplifies the received filtered RX signal and delivers it to another duplex filter 18, which contains the transmitting part (TX) 19 and the receiving part (RX) 20. The function of the duplex filter is to separate the TX signal from the RX signal and prevent leakage of the TX signal to the receiving circuit 21.

Signals received by antennas 10, 11, 12, and 13, respectively, and processed in TMA blocks 6, 7, 8, and 9, respectively, travel along diversity branches A, B, C, and D, respectively.

The radio base station 1 comprises duplex filters 22-25 and low noise amplifiers (LNAs) 26-29, one for each TMA unit. The main component of a radio base station is transceivers 30, 31 (TRX1, TRX2). Depending on the capabilities that the transceiver has and the bandwidth of the traffic onto which the radio base station is designed, there may be only one TRX or many more transceivers than the two shown.

The device shown in FIG. 1 implements 4-fold (over 4 paths) diversity using 4 feeders.

Figure 2 shows the frequency spectrum illustrating the range of frequencies that can pass through the RX filter 22, this range is the full band 32 RX provided by the service. The radio channel through which the RX signal is received by the transceiver and the TX signal is transmitted by the same transceiver is called a user channel. Since there are two transceivers shown in FIG. 2, there are two user channels, each shown with a small rectangle. The frequency band occupied by the user channels is called the user band, which is indicated by the bracket 33. In each of the four branches there is a corresponding user band, and it is the same (in kHz) in all branches. The feeder, however, is capable of transmitting signals at all frequencies up to several GHz (gigahertz), including the full 32 RX band. Thus, it is obvious that the feeder in each branch is used with low efficiency.

In principle, a single TRX is sufficient to process the diversity reception of four RX signals and obtain an improved RX signal. The radio base station, however, is designed to handle large volumes of traffic, and therefore, as well as for reliability reasons, it contains several TRX.

For this reason, the output of each LNA is connected to all the transceivers of the radio base station, as shown by various arrows, collectively denoted by 34.

US Pat. No. 6,505,041 discloses a base station with an antenna diversity system coupled to a splitter from which the antenna signals are supplied to respective receivers via separate feeders.

A drawback of the prior art is that each branch requires its own feeder. A multi-antenna diversity antenna system will thus require as many feeders as there are antennas. Feeders are expensive and also have a lot of weight. Antennas are less expensive. Therefore, systems containing multiple diversity antennas are economically inefficient, although they would be advantageous in terms of reception quality.

SUMMARY OF THE INVENTION

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

A distinctive feature of the invention is to shift / frequency convert the RX signal received by one diversity antenna to an unused frequency and combine / combine the frequency converted signal with an RX signal that has not been frequency converted, and transmit the resulting composite signal to single-feed radio base station.

Depending on the radio communication system in which the invention is used, the meaning of “frequency” and “signal frequency” may be different. Preferred embodiments of the invention are cellular mobile radio systems such as WCDMA (Wideband Code Division Multiple Access), GSM (Global System for Mobile Communications), AMPS (Mobile Telephony), NMT (NMT cellular).

The signal bandwidth in the WCDMA system corresponds to a frequency of 5 MHz, in the GSM system - 200 kHz, in AMPS - 30 kHz and in NMT - 25 kHz. A signal with such corresponding bandwidths is shifted in frequency to another unused (this base station) part of the frequency range.

In the WCDMA system, a 5 MHz signal contains speech and / or data from several users, in a GSM system, a 200 kHz signal contains speech and / or data from users, which can be up to eight (8), in AMPS and NMT, 30 and 25 kHz signals contain speech and / or data from one (1) user. Thus, in practice, the frequency of a signal is a frequency band.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 is a block diagram of a 4-way diversity system according to the prior art,

FIG. 2 is a frequency diagram illustrating a prior art diversity system of FIG. 1,

Figure 3 is a block diagram of a first embodiment for a 4-way diversity system in accordance with the invention,

4 is a frequency diagram illustrating a first embodiment of the invention,

5 is a block diagram of a second embodiment for a 4-way diversity system in accordance with the present invention, and

6 is a frequency diagram illustrating a second embodiment of the present invention,

7 is a block diagram of a third embodiment of the invention,

8 is a frequency diagram illustrating a third embodiment of the present invention,

Fig.9 is a modification of the first embodiment,

Figure 10 is a frequency diagram correlated with the modification of Figure 9,

11 is a block diagram of a fourth embodiment of the invention,

12 is a frequency diagram illustrating a fourth embodiment,

13 is a block diagram of a fifth embodiment comprising a separate frequency converter unit, and

Fig. 14 is a frequency diagram associated with a frequency converter unit.

DETAILED DESCRIPTION OF EMBODIMENTS

Figure 3 illustrates an embodiment of the invention. Elements similar to those shown in FIGS. 1 and 2 are denoted by the same reference numerals. The amplifier 35 according to the invention, mounted on a mast, comprises frequency converters 36, 37, 38, each of which is connected to a corresponding antenna 11, 12, and 13 for shifting the frequency of the received RF antenna signal to the corresponding unused frequency by mixing the RF antenna signal with the corresponding reference signal f1 , f2 and f3 of a predetermined frequency. The signal received by the antenna 10 is not shifted in frequency. The reference signal may be a continuous signal (CW), a local oscillator signal, or any equivalent signal.

The reference signal does not occupy the frequency band. Accordingly, the signal definition given above 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 frequency-shifted signal at an intermediate frequency (IF). The output of each frequency converter is connected to the corresponding bandpass filter IF1, IF2 and IF3. The amplified, non-transformed original radio signal received by the antenna 10 in the diversity branch A, and the IF signals in the corresponding branches B, C, and D are fed to a combiner (adder) 39, in which they are combined into a composite signal, which passes to the bandpass filter RX2 in duplex the filter 18. A duplex filter is connected to the feeder 2. Accordingly, a composite signal containing signals from the respective diversity diversity branches AD is transmitted to the radio base station 1 via a single feeder.

The IF1 filter prevents IF signals from leaking from the converters 37 and 38 to the diversity branch B. IF2 and IF3 filters contain similar functions.

4 is associated with FIG. 3 and is a frequency spectrum illustrating signals at various locations in the TMA and in the feeder. The user band is shown at position 33, and the three intermediate frequencies are shown at 40, 41 and 42. In this case, the feeder is used with three times more efficiency compared to the device known from the prior art shown in FIGS. 1 and 2.

In the shown embodiment, the received radio signals are up-converted to intermediate IF frequencies above the user band 33. The IF frequencies are mutually different, that is, the three IF signals at the output of the frequency converters have different IF frequencies.

The frequency range passed by the RX1 filter is shown at 43. The frequency range passed by the RX2 filter is indicated by the full RX band. It should be noted that IF frequencies must fall within the unused portion of the full RX band. In the embodiment shown, upconverted IF signals should fall within the range to the right of the frequency range 43 passed by the filters RX1. In a situation in which the frequency range 43 of FIG. 4 is shifted to the right to a greater extent, as shown by the dash 44, the IF signals must fall into the range to the left of the dash so as not to interfere with the user band 33. The RX signals are thus converted with decreasing frequency in IF below user band 33. There may be situations in which IF signals fall in the range on either side of the user band.

The device shown in FIG. 3 provides 4-way diversity using a single feeder.

At the radio base station, the signals transmitted through the feeder pass through a duplex filter 22, a low-noise amplifier 26, and enter the transceiver 30, in which they are divided into four RX paths. Signals associated with diversity branches B, C, and D are frequency converted. The signals in each of the A-D diversity branches are subject to diversity processing. Diversity processing may be performed in the diversity receiver.

The device shown in FIG. 5 is similar to that shown in FIG. 3, but in this embodiment, the mast-mounted amplifier 45 comprises only one frequency converter 36. In combiner 39, the original signal in diversity branch A is combined with the IF signal in branch B into a composite signal, which is transmitted to the radio base station via a single feeder 2.

This device provides 2-way diversity using a single feeder. The frequency spectrum in a single feeder 2 is shown in Fig.6.

A device providing 4-way diversity using two feeders is shown in FIG. 7. This device is implemented by doubling the device shown in FIG. 5 and uses two TMAs 45. Feeders 2, 4 of the two TMAs are connected to the corresponding duplex filter in the radio base station. As indicated above, in principle, it is possible to use only one TRX, but in practice, the radio base station contains several transceivers. It should be understood that both feeders 2 and 4 transmit the same two user bands 33 and the same intermediate frequencies 40-42. The frequency diagram shown in FIG. 8 is thus identical for the two feeders.

An advantage of the TMA embodiments in which the direct antenna signal is combined with IF signals and the resulting composite signal is transmitted through a single feeder to the radio base station is that existing radio base stations do not need to be modified since they already contain frequency converters, whereby IF signals plus direct RF signals are converted to a second IF frequency.

In the apparatus of the present invention, it is achieved that diversity signals are sent to the radio base station by a reduced number of feeders compared to the prior art, in which there are as many feeders as diversity antennas, and each diversity reception signal is transmitted on its own feeder.

FIG. 9 illustrates a modification of the embodiment shown in FIG. 3, in which all antenna signals are frequency converted. An additional frequency converter 46 is inserted into the diversity branch A corresponding to the antenna 10. In this embodiment, the four IF signals are combined into a composite signal, which is transmitted to the radio base station via a single feeder 2. This provides 4-way diversity on one feeder. In this embodiment, the radio base station contains only one duplex filter, one low noise amplifier and one transceiver, although this is not shown in the drawing.

Since only one transceiver is used, only one user channel is used in the user band, and therefore, double rectangles are not shown in the frequency diagram of FIG. 10. In this embodiment, the signals that are passed by the RX1 filters may be at a level of approximately several GHz (10 ⁹ ), and the IF signals at a feeder may be at a level of approximately several GHz (10 ⁷ ). The reference frequencies f1-f4 fall into the frequency range in the gap between them.

A modification of the devices shown in FIGS. 5 and 7 provides for frequency conversion of all diversity antenna signals and the use of an additional frequency converter similar to the frequency converter 46 in the embodiment of FIG. 9.

11, RX signals, i.e. the signals of antennas 11, 12 and 13 are subjected to the first frequency conversion in frequency converters 36, 37, 38 (f1, f2, f3 can be of the same frequency, but in this case f5, f6, f7 must have different frequencies), which are connected to the filters IF1, IF2 and IF3. The RX signal of antenna 10, however, does not undergo frequency conversion to TMA. A feature of the embodiment of FIG. 11 consists in the fact that the frequency-converted IF signals at the outputs of the filters IF1, IF2 and IF3 are subjected to a second frequency conversion in the frequency converters 47, 48, 49 by mixing them with the second set of reference signals f5, f6 and f7 and filtering the resulting signals into IF filters labeled RX3, RX4, and RX5 connected to frequency converters 47-49. The direct source signal of the antenna passes through the filter RX1 in the duplex filter 14, the low-noise amplifier 17 and the second filter RX1, similar to RX1 in the duplex filter 14, and combines in combiner 39 with the frequency-converted signals at the output of the RX3-RX5 filters. The composite signal in all diversity branches is routed through a single feeder 2 to the radio base station.

The reference signals f5-f7 are selected so that the signals at the output of the filters RX3-RX5 fall at the frequencies shown in FIG. 12 by the bracket 50 adjacent to the frequency shown by the bracket 51 of the filtered direct signal. This embodiment provides for the use of surface acoustic wave (SAW) filters, designated IF1-IF4, having steep characteristics and well-defined passband frequencies.

13 illustrates an embodiment comprising a frequency converter unit 52 connected between a mast amplifier 35 and a radio base station 1. The frequency converter unit is used in conjunction with radio base stations that do not have enough frequency converters to convert the frequency of the divided signals to the same frequency so as to provide diversity processing for the divided signals.

In FIG. 13, the TMA 35 is similar to that shown in FIG. 9, but the designations used for filters and reference frequencies are different. A composite signal containing IF signals at different IF frequencies is supplied to the block of the frequency converter 52 by a single feeder 2.

The frequency converter unit 52 comprises a duplex filter 53 together with a TX filter and a filter 54 (RX2-5). The duplex filter is connected to the frequency converters 55-58, of which the converter 55 is connected to the duplex filter 59, and the converters 56-58 are connected to the respective filters 60-62. The RX filter from duplex filter 59 and filters 60-62 are similar to the corresponding RX1 filters in TMA 35. The reference signals f5-f8 are selected so that the resulting frequency-converted signals at the outputs of the frequency converters 55-58 have the same frequency. Filtered, frequency-converted signals are output to the outputs of the frequency converter unit and are suitable for diversity processing.

The frequency diagram of the signals appearing in the feeder and the block 52 of the frequency Converter, shown in Fig. The frequency diagram for the composite signal in feeder 2 is the same as that shown in FIG. 9. It should be noted that the signal RX1 in the diagram illustrates the four output signals of the frequency converter unit.

Although not shown in the drawings, it should be understood that the noise reduction filter not shown is inserted after the low noise amplifier 17 into the diversity branch A, which is the branch transmitting the original, non-frequency-converted signal RX.

In many of the above embodiments, the filter RX2 and RX2-5, respectively, can be omitted if the filters RX2-RX5 at the outputs of the frequency converters prevent their signals from leaking into an adjacent diversity branch.

Claims (16)

1. A method of reducing the number of feeders between the radio base station (1) and the receiver diversity antenna (RX) device, which contains at least two spatially separated antennas (10-13), each of which is designed to receive separate radio frequency signals (RF), moreover, all of the mentioned RF signals have the same frequency, characterized in that they convert one or more received antenna signals into a corresponding number of intermediate frequency (IF) signals by mixing with the first set of the corresponding number reference signals (f1-f4) combine the signals received over all antennas, and one or more of these signals were converted in frequency to form a composite signal, which is sent to a radio base station via a single feeder (2, 4). 2. The method according to claim 1, wherein the diversity antenna device comprises n antennas, where n is an integer, and all received antenna signals are converted except one, and the non-converted antenna signal is sent, together with all converted IF signals, to the radio base station on a single feeder, thereby providing diversity on n paths using a single feeder. 3. The method according to claim 1, wherein the diversity antenna system comprises n antennas, where n is an integer, and all received antenna signals are converted and sent to a radio base station via a single feeder, thereby providing diversity on n paths using one feeder. 4. The method according to claim 1, in which IF signals are converted to second IF frequencies by mixing them with a second set of reference signals (f5-f7) to obtain a second set of IF signals, which are sent to the base station by a single feeder. 5. The method according to claim 1, wherein the diversity antenna device comprises a first (10) and a second (11) antenna, wherein the second antenna signal is converted to an IF signal and the IF signal is sent along with the non-converted signal of the first antenna to the radio base station via single feeder (2), thereby providing diversity in 2 ways using a single feeder. 6. The method according to claim 1, in which two diversity antenna devices are used, one of which contains the first (10) and second (11) antennas, and the other contains the third (12) and fourth (13) antennas, and the RF signals are converted from the second and fourth antennas to the first and second IF signals, both of the same intermediate frequency, send the unformed signal of the first antenna to the base station together with the first IF signal through the first feeder (2), and send the untransformed third antenna signal to the base station together with the second IF signal at the second feeder (4), thereby providing 4-way diversity using two feeders (2, 4). 7. The method according to any one of claims 1 to 5, in which IF signals are converted into other IF signals having the same intermediate frequency in the radio base station by mixing them with a set of reference signals (f5-f8) and subjected to diversity processing twice converted frequency signals at a common intermediate frequency. 8. A receiver diversity antenna (RX) device comprising at least two diversity antennas (10-13), each of which is designed to receive separate RF signals of the same frequency, characterized in that it contains one or more converters (36-38 ) frequencies, each of which is designed to convert the corresponding antenna signal into a corresponding intermediate frequency signal (IF signal) by mixing it with a predetermined frequency (f1, f2, f3 or f4), combiner (39), combining the signals received by all antennas, at cm of said one or more signals are converted in frequency to form a composite signal which is sent to the radio base station on a single feeder (2, 4). 9. The receiver diversity antenna (RX) device of claim 8, wherein the RX signal from the diversity antenna is transmitted along the diversity branch (A-D), with each but one diversity branch having a frequency converter (36-38). 10. The receiver diversity antenna device (RX) of claim 8, wherein the RX signal from the diversity antennas is transmitted along the diversity branch (A-D), and a frequency converter (46, 36-38) is provided in each diversity branch. 11. The receiver diversity antenna (RX) device of claim 8, comprising a second set of frequency converters (47-49) for converting a first set of IF signals into a second set of IF signals for transmission to a radio base station via a single feeder. 12. The receiver diversity antenna (RX) device of claim 8, wherein there are two diversity antennas (10, 11), one (10) of which is connected to a first duplex filter (14) for receiving and transmitting, and a single converter ( 36) a frequency that converts the signal of the second antenna (11) to an intermediate frequency to generate the IF signal, with the combiner (39) combining the original RX signal from the first antenna (10) with the IF signal into a composite signal, and a single feeder (2) directs the composite signal to the base station, thereby providing 2 path diversity using one feeder (2). 13. The receiver diversity antenna (RX) device according to claim 9, characterized in that the diversity antenna device is doubled to obtain a composite diversity antenna device comprising four antennas (10-13) and two feeders (2, 4), each diversity device The antenna contains an appropriate single feeder, providing 4-way diversity using two feeders. 14. A radio base station (RBS) comprising a transceiver (TRX) with a plurality of frequency converters designed to provide frequency-converted signals, called diversity signals, at the same frequency, and signal processing means for processing diversity signals to obtain improved signal, characterized in that it contains means connected to the input of the transceiver and designed to receive from a single feeder at least one signal between hydrochloric frequency (IF signal) with a frequency not converted by RX antenna signal and / or other converted IF signals by frequency and supplying the last-mentioned signals to respective ones of said frequency converters for providing diversity reception of said signals. 15. Communication node containing a radio base station (RBS), at least one mast-mounted unit (TMA) with filters (14) and RF amplifiers (17), at least two antennas (10-13) to provide diversity, and the signals received by the antennas are RF signals having the same frequency, characterized in that one or more frequency converters (36-38) are provided in the TMA, each of which is designed to convert the antenna signal to the corresponding intermediate frequency signal (IF ) by mixing it with s At the previously set frequency (f1, f2, f3 or f4), combiner (39), combining the signals received by all antennas, and one or more of the mentioned signals were converted in frequency to form a composite signal, which is fed to a single feeder (2, 4) passing between TMA and RBS. 16. The communication node according to claim 15, characterized in that it comprises a block of frequency converters for use with a single feeder (2, 4), in which a plurality of signals at mutually different frequencies are routed along a single feeder, while the block of frequency converters contains many converters ( 55-58) frequencies for converting said signals into a corresponding number of signals of the same frequency (RX1).

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