JP2000049648A - Smart antenna system based on spatial frequency filter bank technology - Google Patents

Abstract

PROBLEM TO BE SOLVED: To flexibly perform coping in actual use, to reduce the influence of noise and to improve communication quality by simultaneously and parallelly processing plural beams by the single control of an amplitude and a phase to the corresponding antenna unit in a matrix antenna group of a spatial frequency filter in a spatial frequency filter bank. SOLUTION: In this antenna system, from a base station 10, encoded or modulated signals are transmitted through the antenna system 20 where many transmission antennas and the spatial frequency filters are arranged to respective branch stations 40 and 50 and a reflector. The signals fed back by the respective branch stations 40 and 50 are received by a reception antenna system 30 where many reception antennas are arranged, and after selection and arrangement to the beams or channels are performed by the internal spatial frequency filter, they are returned to the base station 10 again and a succeeding processing is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a smart antenna system based on spatial frequency filter bank technology. More specifically, the present invention can perform high-efficiency parallel processing on each beam by independently processing the transmitted or received signal according to each different beam, and can achieve hardware precision and software complexity. The present invention relates to a smart antenna system capable of improving communication quality such as system capacity, distance, range, and the like by greatly reducing the size of the system.

[0002]

2. Description of the Related Art The current smart antenna system (SAS) uses a beam switch (SWITCHED).
BEAM) system and Adaptive Zero Adjustment (ADAPTIV)
ENULLING) system. In the case of a beam switching system, a plurality of beams are sequentially transmitted or received by dividing a space by a time sharing method. However, when the number of beams increases significantly, the time allocated to each beam runs short, which greatly limits the flexibility of use, and therefore cannot meet the demand for high efficiency.

In the case of a smart antenna system of adaptive null adjustment, the range of the antenna magnetic field is automatically adjusted according to the environment of the user and the dynamic range of the antenna is adjusted in a dynamic manner according to the environment and the user position. I do. Then, a dynamic null adjustment operation is performed for the interference to improve the transmission and reception efficiency. A typical situation of an adaptive null adjustment consisting of eight antenna units is as shown in FIG. 7 (according to GloMo / VirginiaTech). The problems of this system are shown below.

[0004] 1. As shown, the gain of the antenna may be slightly impaired by the null adjustment. Also, since the change rate of the field type near the zero adjustment is large,
Slight differences in angles can cause large changes in the damping effect. In addition, accurate positioning with respect to the user becomes difficult due to the influence of the environment, and the effect of zero adjustment is limited.

[0005] 2. 2. In order to achieve the dynamic null adjustment, requirements for hardware linearity, balance, and precision become strict, resulting in an increase in cost. The complexity of the algorithms required for positioning a large number of users and for nulling the field type. Also, since the update rate of the antenna field type is high, a high level of arithmetic processing capability is required.

[0006] 4. Due to the finite number of channels of the spatial frequency filter, it is difficult to distribute to a large number of users. If the number of users exceeds the number of beam nulls that can be controlled by the system, the null adjustment will not be able to accommodate the number of users, causing a problem of uneven distribution.

[0007] 5. In the case of wireless communication, the transmission and reception of the base station adopt an independent arrangement, and the difference between the frequencies of the uplink and downlink is quite large, so that there is almost no relationship between transmission and reception. This makes it difficult to evaluate the field type of the transmitting antenna.

[0008] The conventional smart antenna system of adaptive null adjustment has a complicated configuration of hardware and software and a heavy load because of the large number of users and the large uncertainty of the environment. Too big. Moreover,
Due to its limited functionality, either beam switching or adaptive nulling antenna systems cannot simultaneously provide the advantages of both high efficiency and simplicity.

[0009]

In order to solve the above problems, the present invention provides a transmitting / receiving system having a spatial frequency filter bank including a plurality of spatial frequency filters and a matrix antenna group including a plurality of antennas. And simultaneously processing a plurality of beams in parallel by independent control of the amplitude and phase for the corresponding antenna units in the matrix antenna group of the spatial frequency filter in the spatial frequency filter bank, whereby the conventional beam switching system Solves the problem that the hardware and software of the conventional adaptive null adjustment system are complicated without the need for complicated arithmetic rules because it can solve the problem of inefficiency and simplify the configuration. Provided is a smart antenna system that can be easily configured.

Further, the present invention performs parallel processing on each channel or beam independently,
The gain of the antenna can be increased, the strength of the carrier signal can be improved, side lobes and interference can be reduced, and each parameter of the spatial frequency filter bank can be controlled from the base station via the antenna controller. The present invention provides a smart antenna system capable of closing a spatial frequency filter channel having no user and improving the efficiency.

[0011] The present invention also provides a smart antenna system characterized in that the entire airspace is covered by beams so that beam distribution for a large number of users can be achieved easily and easily.

Further, the present invention applies a spatial frequency filter to increase the side lobe level even if the error between the amplitude and the phase is considerably large.
Provided is a smart antenna system characterized in that it can reduce the requirement for precision of hardware and can be constructed at low cost.

Further, the present invention can be applied to the construction of a matrix antenna having linearity, an annular shape, a flat surface, and the like. When a linear matrix antenna is adopted, the field type of each antenna unit is used to cover the azimuth, Provided is a smart antenna system characterized in that an effect of increasing a gain is achieved.

The present invention can be applied to signal sources of various types, such as electromagnetic waves, sound waves, and ultrasonic waves.
A smart antenna characterized in that it can be used for many systems such as A, TDMA, and CDMA and for many signal length modulations, and can be used not only for information transmission but also for measurements and positioning. Provide system.

[0015]

FIG. 1 shows a typical application of an antenna system based on the spatial frequency filter bank technology of the present invention. In the figure, the base station 10
The encoded or modulated signal is transmitted to each branch station 40, via an antenna system 20 in which a number of transmitting antennas and spatial frequency filters are arranged.
Send to 50 or reflector. The signals fed back by the respective branch stations 40 and 50 are received by the receiving antenna system 30 in which a large number of receiving antennas are arranged, and selection and arrangement of beams or channels are performed by an internal spatial frequency filter. Returns and performs subsequent processing.

Further, the transmitting antenna system 20 and the receiving antenna system 30 of the present embodiment are constructed so that spatial frequency filtering (parallel processing) can be independently performed on a large number of beams to be transmitted or received. I have. When a large number of signals are transmitted, the signals are processed by a large number of internal spatial frequency filters, then the divided amounts of the processed signals are combined by different edders, and finally, conversion / high-frequency modulation and carrier conversion are performed by different antenna units. Make a call. The signals received by each antenna unit of the receiving antenna system are individually added according to the distribution of the signals, processed by a designated digital beamformer and then returned to the base station. Then, the transmitting antenna system 20
And a number of digital beamformers inside the receiving antenna system 30 constitute a spatial frequency filter bank, which reduces the required level of hardware precision and simplifies software complexity.

The structure of the transmitting antenna system comprises a spatial frequency filter bank 23, a matrix antenna 25, and an antenna controller 28, as shown in FIG. The spatial frequency filter bank 23 includes a plurality of digital beamformers 21 and a plurality of edders 22,
The signal received by the system bus 27 of the base station 10 is received and processed.

The spatial frequency filter bank 23 is controlled by an antenna controller 28 to control the parameters of each digital beamformer 21 and
The user-free spatial frequency filter channel can be closed at the appropriate time. The signals sent from the respective eders 22 are sent to the matrix antenna 25 via the transmission bus 24. This matrix antenna 2
5 includes a plurality of antenna units 26, each of which is provided with a plurality of digital-to-analog converters (DACs), an intermediate frequency amplifier, and a transmitting antenna 26. Is configured.

A specific branch station 40 or 50
The signal to be transmitted to the base station 10 is encoded by the base station 10, subjected to spatial frequency filter processing by the beamformer 21 set to correspond to the branch station, and set by the digital beamformer 21 to the set amount of each antenna unit 26. Is calculated,
It is sent to each corresponding eder 22. Also,
The signals to be sent to the other branch stations at the same time are also processed by the above-described method, sent to the eders 22, added, and then digital-analog converted and intermediate frequency amplified by the respective antenna units 25 at the output ends of the respective eders 22. After high-frequency and power amplification, radiate into the air.

As described above, the signals sent by the base station 10 by the respective digital beamformers 21 in the spatial frequency filter bank 23 are:
Since parallel processing is performed individually, there is no adverse effect on other digital beamformers 21. Also, there is no risk that the system will give a load. An antenna controller 28 for controlling each of the digital beamformers 21 not only gives operation parameters but also performs zero adjustment on known neighboring radiation sources in advance to avoid interference.

As shown in FIG. 3, the requisition antenna system of this embodiment includes a spatial frequency filter bank 34 connected to a system bus 37 of the base station 10, a matrix antenna 31, and an antenna controller 36. The spatial frequency filter bank 34 comprises a number of digital beamformers 35 and connects to the base station 10 via a system bus 37. System bus 3
7 also transmits branch station positioning information. This information is sent to an antenna controller 36 at the bottom of the drawing, and the antenna controller 36 controls the work parameters to be sent to the respective digital beamformers 35, as well as the branch station and the digital beamformer. A relationship with the former 35 is determined. Further, as described above, the compensation of the hardware error and the zero adjustment process for the predetermined interference are performed in advance, and the spatial frequency filter channel without the user can be closed.

The matrix antenna 32 includes a receiving antenna 321, a high-frequency amplifier, an intermediate frequency amplifier, an analog-to-digital converter, and a digital down-converter, which are sent from the branch station 40 or 50. The signal is received by the antenna unit 32 and subjected to high frequency amplification, intermediate frequency amplification, analog-to-digital conversion, and digital down-conversion as described above, resulting in a shift to a type 90 degree having multiple basebands. Sends out an output signal of a certain signal, and then puts it on the receiving bus 33, and then, by means of the respective digital beamformer 35, the respective antenna unit 32
, And add by a plurality of weighting methods, and output a specific spatial frequency filter (amplitude and phase of a signal obtained by weighting a plurality of types of signals with a plurality of weights)
Is formed, and finally sent to the base station 10 to perform the subsequent processing.

In the construction of such a receiving antenna system, since the spatial frequency filter bank 34 is composed of a plurality of digital beamformers 35 connected to the bus 33, each digital beamformer 35 simultaneously transmits data on the bus. And can perform parallel processing. Therefore, good operation efficiency can be provided.

[0024]

According to the construction of the transmitting antenna system and the receiving antenna system, the amplitude and phase of each antenna unit can be controlled independently. For example, in the case of a spatial frequency filter channel having eight antenna units, as shown in the spatial frequency filter field type of FIG. 4, the effect of easily reducing the level of the side lobe is shown. In the case where a large number of beams are processed by a spatial frequency filter bank including a plurality of digital beamformers, the formed field types are as shown in FIG. When multiple beams are present at the same time, each beam is kept in good condition and there is no problem of interference. The level of each side lobe is kept at a much lower level. Thus, the effect of the present invention has been sufficiently proved. Also, as shown in FIG. 6, even when the error between the amplitude and the phase is considerably large, substantially the same effect can be obtained. Further, as compared with the prior art, the present invention can tolerate a larger error in hardware and requires less precision for hardware, so that a hardware device can be constructed at low cost.

As mentioned above, the smart antenna system based on the spatial frequency filter bank technology of the present invention can process a plurality of beams in parallel at the same time, and can reduce the requirement for the precision and complexity of hardware and software. In addition, the antenna controller can perform processing such as setting parameters, performing zero adjustment in advance, and closing unused channels at appropriate times for each spatial filter (digital beamformer) in the spatial frequency filter bank. . Therefore, since it is possible to flexibly cope with actual use and reduce the influence of noise,
Communication quality can be greatly improved.

[Brief description of the drawings]

FIG. 1 illustrates an exemplary embodiment of the antenna system of the present invention.

FIG. 2 is a block diagram of a transmitting antenna system of the present invention.

FIG. 3 is a block diagram of a receiving antenna system of the present invention.

FIG. 4 is a diagram showing a field type in which one spatial frequency filter is formed by eight antenna units.

FIG. 5 is a chart showing typical functions of the spatial frequency filter bank of the present invention.

FIG. 6 is a table showing functions of the present invention when there is an error in amplitude and phase.

FIG. 7 is a diagram showing a typical field type of a conventional adaptive null adjustment antenna system.

[Brief description of reference numerals]

 Reference Signs List 10 base station 20 transmitting antenna system 21 digital beamformer 22 adder 23 spatial frequency filter bank 24 transmitting bus 25 matrix antenna 26 antenna unit 261 antenna 27 system bus 28 antenna controller 30 receiving antenna system 31 matrix antenna 32 antenna unit 321 antenna 33 reception Bus 34 spatial frequency filter bank 35 digital beamformer 36 antenna controller 37 system bus 40, 50 branch station

Claims (9)

[Claims] 1. A spatial frequency filter bank, a matrix antenna, and an antenna controller, wherein the spatial frequency filter bank includes a plurality of digital beamformers and a plurality of adders, and the matrix antenna includes a plurality of antenna units. A transmitting antenna system, a spatial frequency filter bank, and a matrix antenna, wherein the antenna controller is a means for providing parameters of required terms to the spatial frequency filter bank.
An antenna controller, wherein said spatial frequency filter bank comprises a plurality of digital beamformers,
The matrix antenna comprises a plurality of antenna units, and the antenna controller comprises: a receiving antenna system, which is a means for providing frequency filtering parameters of the spatial frequency filter bank; A smart antenna system based on the spatial frequency filter bank technology, which can perform parallel processing of the above and can flexibly control the transmission / reception quality by an antenna controller. 2. The spatial frequency filter bank technology according to claim 1, wherein each antenna unit of the transmitting antenna system has a digital-to-analog converter, an intermediate frequency amplifier, and a high frequency amplifier. Smart antenna system based. 3. The receiving antenna system according to claim 1, wherein each of the antenna units includes a high frequency amplifier, an intermediate frequency amplifier, an analog / digital converter, and a digital down converter. A smart antenna system based on the spatial frequency filter bank technology. 4. The smart antenna system according to claim 1, wherein a linear antenna construction is used as the matrix antenna. 5. The smart antenna system according to claim 1, wherein a ring antenna construction is used as the matrix antenna. 6. The smart antenna system according to claim 1, wherein a planar antenna construction is used as the matrix antenna. 7. The smart antenna system can be used as a signal source of electromagnetic waves, sound waves, and ultrasonic waves, and the FD
The smart antenna system based on spatial frequency filter technology according to claim 1, wherein the smart antenna system can be used in signal modulation forms of MA, TDMA, and CDMA. 8. The smart antenna system according to claim 1, wherein the antenna controller can close a user-less spatial frequency filtering channel at an appropriate time. 9. The smart antenna system according to claim 1, wherein the antenna controller can perform zero adjustment in advance for a predetermined or larger interference source.