KR20060020986A - Switching beam antenna system with phase modulation transmit diversity function - Google Patents

Abstract

The present invention relates to a system in which a phase modulated transmit diversity function is added to a switching beam antenna system which has a direction and a beam width of the same antenna when transmitting and receiving data using a directional antenna in a mobile communication base station.

A switching beam antenna system for improving a transmission performance by applying phase modulation to a signal transmitted in each beam so that phase modulation transmission diversity can be performed when the mobile communication base station transmits a plurality of beams. A plurality of antenna elements arranged in azimuth direction with directivity, and signals received from the plurality of antenna elements are separated into a plurality of independent beams and output, and a plurality of independent beams transmitted through the plurality of antenna elements, respectively A radiating butler beamformer, a plurality of duplexers for band-filtering a plurality of received signals separated from the butler beamformer, and switching output to band-filter, transmit and receive a plurality of transmit signals transmitted from a plurality of transmitters; Receive Band Scene Filtered from Multiple Duplexers Down-convert each call to convert the baseband signal of the I-channel signal to the Q-channel, and then convert it to a digital signal and output the digital signal, and receive the digital signals respectively output from the plurality of receivers and despread using spread codes. A plurality of matched filters for respectively detecting and outputting the strength and time of the signal, a beamswitch controller for receiving the strength and time data of the signals respectively output from the plurality of matched filters and outputting transmission and reception beam selection signals; A reception beam switch that receives n digital signals respectively output from a plurality of receivers, and selects and outputs m signals by a reception beam selection signal output from the beam switch controller, and m digital signals selected and output from the reception beam switch Demodulates and outputs the CDMA signal, and spreads the baseband signal into a CDMA signal for transmission. And a plurality of phase modulators for modulating and outputting CDMA signals modulated from the CDMA modem to different phases by a phase modulation control signal of the beamswitch controller, and the plurality of phase modulators. A transmission beam switch for selecting and outputting k signals by transmitting beam selection signals of the beam switch controller to n signals modulated with different phases, and converting the signals selected and output from the transmission beam switches into analog signals, Upconverts the frequency and then amplifies and outputs a plurality of transmitters to each of the multiplexers.

Switching beam antenna, transmit diversity, phase modulation, base station

Description

Switching beam antenna system with Phase Modulation Transmit Diversity Function

1 is a block diagram of a switching beam antenna system according to the prior art

2 is a configuration diagram of a switching antenna system having a phase modulation transmit diversity function according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10-1 to 10-n: multiple antenna elements 20: butler beam forming machine

30-1 to 30-n: Multiple duplexers 40-1 to 40-n: Multiple receivers

50-1 to 50-n: Multiple matching filters 60: Receive beam switch

70: beam switch controller 80: CDMA modem

90-1 to 90-k: a plurality of phase modulation elements 100: transmission beam switch

The present invention relates to a switching beam antenna system, and in particular, a phase modulation transmit diversity function is added to a switching beam antenna system which has a direction and beam width of the same antenna when transmitting and receiving data using a directional antenna in a mobile communication base station. It's about a system.

In general, an antenna system used for a mobile communication base station includes an adaptive array antenna system and a smart antenna system. The adaptive array antenna system or smart antenna system is composed of an array antenna consisting of a plurality of antenna elements, a transceiver connected to each antenna element, and a signal processing unit for beam shaping.

Conventional adaptive array antenna system is disclosed in the publication No. 2000-009562 filed July 28, 1998 in the Republic of Korea. In Publication No. 2000-009592, digital beam shaping is performed by obtaining a weight for forming a beam from a received signal, and the output of the beam shaping machine is input to a rake receiver or a plurality of fingers of a rake receiver. In this case, beam diversity is performed on a signal received with a time difference through multiple paths using an independent beam shaper for each input, so that time diversity is performed. This method has a problem in that the calculation amount of the baseband processor is increased because it is necessary to calculate a weight for forming an optimal beam at a predetermined time.

In addition, we cannot guarantee that the optimal weight calculated using the received signal is optimal even in the case of transmission. In particular, the received signal is used in the frequency division duplexing scheme in which transmission and reception are performed in different frequency bands. The calculated optimal weight has a problem that it is difficult to form an optimal beam in the case of transmission.

Meanwhile, a conventional smart antenna system different from the adaptive array antenna system is disclosed in Korean Patent Application Publication No. 2000-034151, filed on November 27, 1998 in Korea. In Publication No. 2000-034151, when a received signal is distributed at various angles, the signal is stably received by performing despreading by receiving all signals in the direction of the antenna having a received power above a threshold. However, even in Publication No. 2000-034151, a signal can be received by forming an optimal beam in a direction of a user who wants an antenna without calculating an optimal weight at the time of reception, but in the case of transmission, an optimal beam cannot be formed. There was.

Accordingly, an object of the present invention is to switch to a signal that can transmit a signal by forming an optimal beam at the time of transmission without calculating the weight by spatial filtering using an antenna element having directivity in the mobile communication base station to solve the above problems In the beam antenna system, when the mobile communication base station transmits a plurality of beams to provide a switching beam antenna system that can improve the transmission performance by giving a phase modulation to the signal transmitted in each beam.

In the switching beam antenna system of the present invention for achieving the above object, a plurality of antenna elements arranged in azimuth direction with a plurality of directivity and the signals received from the plurality of antenna elements are separated into a plurality of independent beams A butler beam shaper for outputting and radiating a plurality of independent beams transmitted through the plurality of antenna elements, and a plurality of transmissions that are band-filtered on a plurality of received signals separated from the butler beam shaper and transmitted from a plurality of transmitters And a plurality of duplexers for switching and outputting band-filtered signals for transmission and reception, and down-converting the filtered reception band signals from the plurality of duplexers to baseband signals of I-channel signals and Q-channels, and then converting them into digital signals. A plurality of receivers for outputting the plurality of receivers Receives the digital signals outputted from the receiver and despreads them using a spreading code to detect and output the strength and time of the signal, respectively, and receives the strength and time data of the respective output signals from the plurality of matching filters. A beam switch controller for outputting transmission and reception beam selection signals, and a reception beam for selecting and outputting m signals by receiving the n digital signals respectively output from the plurality of receivers and receiving beam selection signals output from the beam switch controller A CDMA modem which receives m digital signals selectively output from the reception beam switch, demodulates and outputs a CDMA signal, and spreads and modulates a baseband signal for transmission into a CDMA signal, and a modulated signal from the CDMA modem. The CDMA signal is changed to a different phase by the phase modulation control signal of the beam switch controller. A plurality of phase modulators for outputting a plurality of phase modulators, and a transmission beam switch for selecting and outputting k signals by transmitting beam select signals of the beamswitch controllers to n signals modulated with different phases from the plurality of phase modulators; And a plurality of transmitters for converting a signal selected and output from the transmission beam switch into an analog signal, up-converting the frequency, and then amplifying and outputting the signal to a plurality of duplexers, respectively.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

1 is a configuration diagram of a switching beam antenna system according to the prior art, and FIG. 2 is a configuration diagram of a switching antenna system having a phase modulation transmit diversity function according to an embodiment of the present invention.

A plurality of antenna elements 10-1 to 10-n arranged in azimuth directions with a plurality of directivity directions and signals received from the plurality of antenna elements 10-1 to 10-n into a plurality of independent beams. Butler beam shaper 20, which separates and outputs a plurality of independent beams to be transmitted through the plurality of antenna elements 10-1 to 10-n, respectively, and a plurality of which are separated from the butler beam shaper 20 A plurality of duplexers (30-1 to 30-n) for band-filtering a received signal of the switching signal and for switching and outputting the band-filtered transmission and reception of a plurality of transmission signals transmitted from the plurality of transmitters (102-1 to 102-n) And a plurality of receivers which down-convert the filtered reception band signals from the plurality of duplexers 30-1 to 30-n, convert them into baseband signals of the I channel signal Q channel, and then convert them into digital signals and output them. 40-1 to 40-n), and the plurality of receivers Multiple matching filters (50-1 to 50-n) which receive the digital signals outputted from (40-1 to 40-n) and despread using spread codes to detect the signal strength and time and output them respectively. And a beam switch controller 70 for receiving the strength and time data of the signals respectively output from the plurality of matching filters 50-1 to 50-n and outputting transmission and reception beam selection signals, and the plurality of receivers. A reception beam switch 60 which receives n digital signals respectively outputted from (40-1 to 40-n) and selects and outputs m pieces by the reception beam selection signal output from the beam switch controller 70; A CDMA modem 80 which receives m digital signals selectively output from the reception beam switch 60, demodulates and outputs a CDMA signal, and spreads and modulates a baseband signal for transmission into a CDMA signal; and the CDMA modem Modulating the CDMA signal from the beam switch (80); A plurality of phase modulation elements 90-1 to 90-k and a plurality of phase modulation elements 90-1 to 90-k that are modulated to different phases by the phase modulation control signal of the device 70 and output. A transmission beam switch 100 which selects and outputs k signals by the transmission beam selection signal of the beam switch controller 70 from the n signals modulated at different phases from the transmission beam switch 100 and the transmission beam switch 100. It consists of a plurality of transmitters 102-1 to 102n that convert the output signal into an analog signal, upconvert the frequency, and then amplify and output the amplified signals to the plurality of duplexers 30-1 to 30-n.

Referring to Figure 2 described above will be described in detail the operation of the preferred embodiment of the present invention. Referring to the operation of receiving a signal at the mobile communication base station,

The plurality of antenna elements 10-1 to 10-n have a plurality of directivities and are arranged in the azimuth direction, and receive signals transmitted wirelessly through the air. At this time, the butler beam former 20 separates the signals received from the plurality of antenna elements 10-1 through 10-n into a plurality of independent beams and applies them to the plurality of duplexers 30-1 through 30-n. . At this time, n = 2L, and L = 1, 2, 3, .... A plurality of antenna elements (10-1 to 10-n) are arranged in a straight line at half-wavelength intervals, and form four beam patterns by the Butler beam former 20 when n = 4, and a plurality of duplexers 30-1 to 30-n band-filter the plurality of received signals separated from the butler beam former 20 and apply them to the plurality of receivers 40-1 to 40-n. 1 to 40-n) down-convert the filtered reception band signals from the plurality of duplexers 30-1 to 30-n, convert them into baseband signals of the I channel signal Q channel, and then convert them into digital signals. A plurality of receive beam switches 60 and a plurality of matched filters 50-1 to 50-n are applied to the plurality of matched filters 50-1 to 50-n. -n) receives the digital signals outputted from the respective signals and despreads them using a spread code provided from the CDMA modem 80 to detect the signal strength and time, To the position controller 70. The beam switch controller 70 receives the strength and time data of the signals output from the plurality of matching filters 50-1 to 50-n, respectively, and transmits and receives the beam selection signals. And a reception beam selection signal is applied to the reception beam switch 60, and a transmission beam selection signal is applied to the transmission beam switch 100. The reception beam switch 60 includes the plurality of receivers 40-1 to 4-1. CDMA modem 80 through lines 103-1 to 103n by receiving n digital signals respectively output from 40-n and selecting m pieces by the reception beam selection signal output from the beam switch controller 70. The CDMA modem 80 receives m digital signals selected and output from the reception beam switch 60, demodulates them into baseband CDMA signals, and outputs them through line 104-1. 80 includes a RAKE receiver, the receive beam switch 60 The m signals output from the selection are determined by the number of fingers in the RAKE receiver present in the CDMA modem 80 and the strength of the received signal. That is, the m maximum values are equal to the number of fingers of the rake receiver and have no meaning when the number of fingers is larger than the number of fingers. Accordingly, the beam switch controller 70 outputs a reception beam selection signal to select up to m beams having a strength within a range when searching for a beam having the largest signal strength and comparing the beam with the maximum signal strength, and otherwise, the beam strength controller has a maximum intensity. Select only one beam from which a signal is detected. For example, for a rake receiver with four fingers, this signal is applied to all fingers when m = 1, and to two fingers when m = 2, respectively. In addition, when m = 4, one signal is allocated to each finger. The operation of the rake receiver after that is the same as the general Maximum Ratio Combining.

Referring to the operation of transmitting a signal in a mobile communication base station,

The baseband signal for transmission input through line 104-2 is spread modulated by the CDMA modem 80 into a CDMA signal to transmit a plurality of phase modulators 90-1 to 90-k through line 104-3. Is applied. The plurality of phase modulation elements 90-1 to 90-k modulate the CDMA signal modulated by the CDMA modem 80 to different phases by a phase modulation control signal of the beam switch controller 70. To the switch 100. At this time, each of the different phase modulation is modulated to 0.5Hz or less in the beam switch controller 70 and applied to the plurality of phase modulation elements (90-1 ~ 90-k).

On the other hand, the transmission beam switch 100 is composed of a low-power digital switch, the k signal modulated in different phases from the plurality of phase modulation elements (90-1 ~ 90-k) the beam switch controller ( The k signals are selected by the transmission beam selection signal of 70 and applied to the plurality of transmitters 102-1 through 102-n. In this case, the plurality of transmitters 102-1 to 102-n convert the signal output from the transmission beam switch 100 into an analog signal, filter, upconvert, and amplify the plurality of duplexers 30-1 to 30. -n). The plurality of duplexers 30-1 to 30-n switch and output a plurality of antennas 10 to filter and transmit a plurality of transmission signals output from the plurality of transmitters 102-1 to 102-n to a transmission frequency band. -1 to 10-n).

Therefore, since the present invention searches for a direction in which a signal is transmitted spatially and transmits the signal in a narrow beam, a spatial filtering effect can be obtained and interference of other users can be suppressed. In addition, since the beam shaping is performed by receiving the transmission signal from the transmitter, even if the phase and amplitude characteristics of each transmitter are different, the formation of the beam pattern is not affected.

As described above, the present invention can improve the transmission efficiency by forming an optimal beam at the time of transmission without calculating the weight by spatial filtering using an antenna element having directivity in the mobile communication base station. When transmitting with a beam, there is an advantage of improving transmission performance through a transmit diversity function that provides phase modulation to a signal transmitted by each beam.

Claims (2)

A switching beam antenna system, And a plurality of phase modulation elements for modulating and outputting the CDMA signals modulated from the CDMA modem to different phases by the phase modulation control signal of the beam switch controller. The method of claim 1, And the phase modulation is transmit diversity modulated to a maximum of 0.5 Hz or less.

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