KR20020009079A - Apparatus for controlling transmit diversity - Google Patents

Abstract

PURPOSE: An apparatus for controlling a transmission diversity is provided to improve the performance of a forward link by transmitting a control instruction and differently applying a weight value according to a switch control instruction. CONSTITUTION: A demultiplexing unit(100) divides a pilot channel, a synchronous channel, a paging channel, and a traffic channel by 2 according to a transmission antenna. A symbol repeating unit(200) receives channel data outputted from the demultiplexing unit(100) and repeatedly symbolizes the received channel data. A Walsh spreading unit(300) receives the symbolized data outputted from the symbol repeating unit(200), multiplies the received data by a Walsh code, and spreads the multiplied value. A switching control unit(700) determines whether the Walsh spreading data outputted from the Walsh spreading unit(300) to any antenna among a plurality of antennas. A complex PN(Pseudo Noise) spreading unit(400) receives the data outputted from the switching control unit(700), converts the received data into a PN code, and transmits the PN code to the antenna.

Description

Apparatus for controlling transmit diversity

The present invention relates to transmission diversity for compensating forward link fading in a next generation mobile communication system. More specifically, two antennas are used when a value comparing a difference between pilot signals received from two antennas is within a predetermined range. Therefore, the present invention relates to a control apparatus for transmit diversity, which improves forward link performance by requiring transmission of only one antenna that suffers less fading when out of a certain range.

In general, mobile communication systems use the forward (base station to base station) and the reverse (mobile station to base station) to maximize the number of users who can talk simultaneously within a given bandwidth, and to obtain call capacity, good call quality, and other benefits. Use link power control. The capacity of the system is maximized if the transmit power of each mobile station is controlled to reach the base station with a minimum signal-to-interference ratio. The purpose of the mobile station transmit power control is to control the mobile station transmit power so that the transmit signals of all mobile stations in the region are received at the nominal intensity by the base station receiver so that more mobile stations can communicate with the base station with better call quality. If the transmission power of the mobile station received at the base station is too low, the bit error rate is too high to expect a good quality call. In addition, if the reception power at the base station is too high, the call quality of the mobile station is improved, but the call quality is deteriorated unless the total subscriber is reduced because the interference with other mobile stations using the same channel increases.

The base station supports forward power control by adjusting the forward power corresponding to the power measured at the mobile station. The purpose of the forward power control is to reduce the lost power of mobile stations that are not talking, relatively close to the base station, have little influence of multipath fading and radio wave shading, or have little interference from other base stations, Additional supporting power is provided for mobile stations with high error rates.

In addition, the IS-2000 system currently being used uses various concepts of transmit diversity to compensate for forward link fading, among which orthogonal transmit diversity (OTD) and space time spreading (Space Time Spreading). : STS) diversity is used.

1 is a block diagram showing a first embodiment of a transmission diversity control apparatus according to the prior art.

As shown in FIG. 1, a demultiplexer 100 which separates two antennas to be transmitted from a pilot channel, a synchronization channel, a paging channel, and a traffic channel applied to a control input, and the demultiplexer 100. The symbol repeater 200 receives and outputs data separated by two from the symbol repeater 200, and Walsh multiplies the Walsh code by receiving the symbolized data output from the symbol repeater 200. A complex PN spreader 400 for receiving the Walsh spread data output from the Walsh spreader 300 and spreading the pseudo noise code, and outputting from the complex PN spreader 400 A baseband filter / QPSK modulator 500 for filtering only portions other than the baseband by receiving a pseudo-noise code and quadrature phase shift keying (QPSK), and the baseband filter / QPSK modulator (QPSK) 500) Robu It is composed of a summer 600 for transmitting the four-phase shifted quadrature component (quadrature componen) output to the antenna.

The symbol repeater 200 includes a first symbol repeater 200-1, a second symbol repeater 200-2, a third symbol repeater 200-3, and a fourth symbol repeater 200-4. It consists of

The Walsh diffusion unit 300 includes a first Walsh diffusion unit 300-1 and a second Walsh diffusion unit 300-2.

The complex PN spreader 400 includes a first complex PN spreader 400-1 and a second complex PN spreader 400-2.

The baseband filter / QPSK modulator 500 includes a first baseband filter / QPSK modulator 500-1, a second baseband filter / QPSK modulator 500-2, and a third baseband filter / QPSK modulator. And a fourth baseband filter / QPSK modulator 500-4.

The summer 600 includes a first summer 600-1 and a second summer 600-2.

Referring to the operation of the orthogonal transmit diversity configured as described above, the pilot channel, the synchronization channel, the paging channel and the traffic channel are input to the demultiplexer 100 and the demultiplexer 100 transmits the input channels to each antenna to be transmitted. The two symbols are separated and transmitted to the first symbol repeating unit 200-1, the second symbol repeating unit 200-2, the third symbol repeating unit 200-3, and the fourth symbol repeating unit 200-4. .

The first symbol repeater 200-1 and the second symbol repeater 200-2 repeatedly symbolize the transmitted channels and transmit the channels to the first Walsh spreader 300-1.

In addition, the third symbol repeater 200-3 and the fourth symbol repeater 200-4 repeatedly symbolize the transmitted channels and transmit the channels to the second Walsh spreader 300-2. .

In this case, the first Walsh spreader 300-1 and the second Walsh spreader 300-2 multiply different Walsh codes to give orthogonality to the symbolized channels, and spread the data.

The first Walsh spreader 300-1 and the second Walsh spreader 300-2 respectively output the first complex PN spreader 400-1 and the second complex PN spreader 400. -2).

The first complex PN spreader 400-1 and the second PN spreader 400-2 spread the transmitted data into a pseudo noise code and spread the pseudo noise code into a first baseband filter / QPSK modulator 500-. 1) the second baseband filter / QPSK modulator 500-2, the third baseband filter / QPSK modulator 500-3, and the fourth baseband filter / QPSK modulator 500-4. .

Here, the first baseband filter / QPSK modulator 500-1, the second baseband filter / QPSK modulator 500-2, the third baseband filter / QPSK modulator 500-3, and the fourth baseband filter / QPSK modulator 500-1. The baseband filter / QPSK modulator 500-4 shifts the phase while filtering portions other than the baseband.

The first baseband filter / QPSK modulator 500-1 and the second baseband filter / QPSK modulator 500-2 transmit the phase shift modulated pseudo noise code to the first summer 600-1. do.

The third baseband filter / QPSK modulator 500-3 and the fourth baseband filter / QPSK modulator 500-4 are phase shift modulated by a second summer 600-2. Send it.

The first summer 600-1 and the second summer 600-2 combine the transmitted four-phase shift keyed abnormal components and transmit the combined four phase shift modulation components to the first antenna and the second antenna.

2 is a block diagram illustrating a second embodiment of a transmission diversity control apparatus according to the prior art.

As shown in FIG. 2, a demultiplexer 100 which separates two antennas to be transmitted from a pilot channel, a synchronization channel, a paging channel, and a traffic channel applied to a control input, and the demultiplexer 100 The symbol repeater 200 receives and outputs data separated by two from the symbol repeater 200, and Walsh multiplies the Walsh code by receiving the symbolized data output from the symbol repeater 200. The spreader 300 receives a Walsh spreading data output from the Walsh spreader 300 and adds the summator 600 to the data, and spreads the pseudo noise code. Quadrature phase shift keying (QPSK) is performed by receiving a complex PN spreader 400 and a pseudo noise code output from the complex PN spreader 400 to filter only portions other than the baseband, and to filter the phases. The baseband filter / QPSK modulator 500 and a four-phase shifted quadrature componen outputted from the baseband filter / QPSK modulator 500 to be transmitted to the antenna. It consists of

The symbol repeater 200 may include a first symbol repeater 200-1, a second symbol repeater 200-2, a third symbol repeater 200-3, and a fourth symbol repeater 200-4. ), The fifth symbol repeating unit 200-5, the sixth symbol repeating unit 200-6, the seventh symbol repeating unit 200-7, and the eighth symbol repeating unit 200-8.

The Walsh diffuser 300 includes a first Walsh diffuser 300-1, a second Walsh diffuser 300-2, a third Walsh diffuser 300-3, and a fourth Walsh diffuser 300-4. It consists of

The complex PN spreader 400 includes a first complex PN spreader 400-1 and a second complex PN spreader 400-2.

The baseband filter / QPSK modulator 500 includes a first baseband filter / QPSK modulator 500-1, a second baseband filter / QPSK modulator 500-2, and a third baseband filter / QPSK modulator. And a fourth baseband filter / QPSK modulator 500-4.

The summer 600 includes a first summer 600-1, a second summer 600-2, a third summer 600-3, a fourth summer 600-4, and a fifth summer. Group 600-5 and sixth summer 600-6.

The operation of the space time spread diversity configured as described above is similar to the overall operation of the orthogonal transmit diversity of FIG. 1 except that in the case of the orthogonal transmit diversity, even and odd bits are transmitted to each antenna. Diversity differs in that even and odd bits are summed again through an adder so that the entire signal is transmitted to each antenna.

However, the orthogonal transmit diversity has a problem in that half of the transmission data is difficult to recover if one of the two antennas undergoes severe fading by transmitting the input signals separated in time.

In addition, the space time spread diversity also has a problem that the gain of the diversity is reduced as one path undergoes severe fading.

Accordingly, an object of the present invention is to solve the above-described problems according to the prior art, and an object of the present invention is that a difference in a value of a pilot signal received by a mobile station from two antennas deviates from a specified threshold. If the received power of one of the two pilots is out of the specified threshold, or if the power difference between the two pilots is within the threshold but persists a range of values for a threshold time, the two antennas will have significantly different fading environments. The control command is transmitted so that the signal of the pilot signal is relatively strong among the two antennas, and the signals received from the two antennas experience similar fading. Report transmit diversity using both antennas By transmitting a control command to the base station to prevent performance degradation due to the fading of the forward link, and to receive a signal transmitted using only one antenna, it is twice as large as that transmitted through two antennas. The present invention provides a transmission diversity control apparatus capable of improving the performance of a forward link by restoring a signal by giving a weight of.

Features of the control apparatus for transmission diversity according to the present invention for achieving the above object, the demultiplexer for separating the two for each antenna to be transmitted from the pilot channel, synchronization channel, paging channel and traffic channel applied to the control input; A symbol repeater for repeatedly symbolizing the data received from the demultiplexer and outputting the data, and a Walsh spreader for multiplying the Walsh code by receiving the symbolized data output from the symbol repeater; Switching control unit for receiving the Walsh spreading data output from the Walsh spreader 300 to determine whether to transmit the entire signal only to one antenna, and by receiving the data output from the switching control unit to spread the pseudo-noise code to the antenna It consists of a complex PN spreader to transmit.

1 is a block diagram showing a first embodiment of a transmission diversity control apparatus according to the prior art;

2 is a block diagram showing a second embodiment of a transmission diversity control apparatus according to the prior art;

3 is a block diagram showing a first embodiment of a transmission diversity control apparatus according to the present invention;

4 is a block diagram illustrating a second embodiment of a transmission diversity control apparatus according to the present invention.

<Explanation of symbols for the main parts of the drawings>

100: demultiplexer, 200: symbol repeater,

300: Walsh diffusion unit, 400: complex PN diffusion unit,

700: switching control unit.

Hereinafter, a preferred embodiment of the transmission diversity according to the present invention will be described with reference to the accompanying drawings.

3 is a block diagram showing a first embodiment of a transmission diversity control apparatus according to the present invention.

As shown in FIG. 3, a demultiplexer 100 for separating two pilot channels, a synchronization channel, a paging channel, and a traffic channel applied to a control input for each antenna to be transmitted, and the demultiplexer 100. The symbol repeater 200 receives the channel data outputted separately from each other by two symbols and repeatedly symbolizes the symbol data, and receives the symbolized data output from the symbol repeater 200 and multiplies the Walsh code. Whether the Walsh spreader 300 and the Walsh spreader data output from the Walsh spreader 300 are transmitted to transmit even and odd bits to each of the two antennas, or one of the two antennas has a good channel environment. The switching controller 700 determines whether to transmit the entire signal only, and receives the data output from the switching controller 700 and spreads the data into a pseudo noise code. It consists of the PN complex spreading portion 400 for transmitting me.

The symbol repeater 200 includes a first symbol repeater 200-1, a second symbol repeater 200-2, a third symbol repeater 200-3, and a fourth symbol repeater 200-4. It is composed of

The Walsh diffusion unit 300 includes a first Walsh diffusion unit 300-1 and a second Walsh diffusion unit 300-2.

The switching controller 700 includes 1 × 2 switches 700-1 and 700-2 for switching Walsh spread data output from the first Walsh spreader 300-1, and the second Walsh spreader 300-. 2) switches from 1x2 switch 700-3 and 700-4 for switching Walsh diffusion data output from 2) and 1x2 switch 700-1 and 1x2 switch 700-3. A first summer 700-5 for summing the output data and a second summer summing for the data output from the 1 × 2 switch 700-2 and the 1 × 2 switch 700-4; 700-6, a 1 × 2 switch 700-7 for switching data output from the first summer 700-5, and data output from the second summer 700-6. 1 × 2 switch 700-8 for switching, and 2 × 1 switch 700-9 for switching data output from the 1 × 2 switch 700-1 and 1 × 2 switch 700-7 ), And are switched out from the 1 × 2 switch 700-2 and 1 × 2 switch 700-8. 2 × 1 switch 700-10 for switching the data to be converted, and 2 × 1 switch for switching the data output from the 1 × 2 switch 700-3 and 1 × 2 switch 700-7. 700-11 and 2x1 switch 700-12 for switching data output from the 1x2 switch 700-4 and 1x2 switch 700-8.

The complex PN spreader 400 receives the data output from the 2 × 1 switch 700-9 and the 2 × 1 switch 700-10, and outputs the data to the antenna. And a second complex PN spreader 400-2 for receiving data output from the 2 × 1 switch 700-11 and 2 × 1 switch 700-12 and outputting the data to the antenna.

Referring to the operation of the transmission diversity configured as described above, the signal input to the demultiplexer 100 is input to the switching controller 700 via the symbol repeater 200 and the Walsh spreader 300.

The switching controller 700 switches 700-1, 700-2, 700-3, and 700-4 (700-7, 700-8) (700-9, 700-) according to a switching control command transmitted from the mobile station. 10, 700-11, 700-12) switch to apply orthogonal transmit diversity with two antennas to transmit even and odd bits to each of the two antennas, or one of the two antennas has a good channel environment It is determined whether to transmit the entire signal only to the antenna of.

In this case, when a signal is transmitted to only one antenna without using orthogonal transmit diversity, the signals separated into even and odd bits are recombined through the first and second summers 700-5 and 700-6. Will be sent.

Herein, the control command from the mobile station is a two-bit signal including control commands for the following three cases.

(1) 00: command to continuously transmit through two antennas using orthogonal transmit diversity,

(2) 01: command to transmit a signal through the first antenna,

(3) 10: command to transmit the signal through the second antenna,

On the other hand, the case of requesting signal transmission to only one antenna of the above control command is as follows.

(1) if the difference between the pilot signals received from the two antennas is outside the specified threshold,

(2) when the difference between the pilot signals received from the two antennas is smaller than the threshold but lasts for a predetermined time or more,

(3) when the received power of one pilot signal is out of a specified threshold,

At the receiving end, orthogonal transmit diversity is applied, the signal is restored by giving the same weight to the case where the signal is received by the two antennas. If the signal is received through only one antenna, the weight is doubled to the antenna receiving the signal. The reception performance can be improved by restoring the signal.

4 is a block diagram illustrating a second embodiment of a transmission diversity control apparatus according to the present invention.

As shown in FIG. 4, a demultiplexer 100 which separates two antennas to be transmitted from a pilot channel, a synchronization channel, a paging channel, and a traffic channel applied to a control input, and the demultiplexer 100. The symbol repeater 200 receives and outputs data separated by two from the symbol repeater 200, and Walsh multiplies and multiplies the Walsh code by receiving the symbolized data output from the symbol repeater 200. Whether to use a space time spread by receiving a spreader 300, a summer 600 that receives Walsh spread data output from the Walsh spreader 300, and adds the data and outputs the data output from the summer 600; Alternatively, the switching controller 800 determines whether to transmit a signal to only one antenna, and receives the data outputted from the switching controller 800 to spread the pseudo noise code. It is composed of a complex PN spreader 400 for transmitting to the antenna.

The symbol repeater 200 may include a first symbol repeater 200-1, a second symbol repeater 200-2, a third symbol repeater 200-3, and a fourth symbol repeater 200-4. ), The fifth symbol repeating unit 200-5, the sixth symbol repeating unit 200-6, the seventh symbol repeating unit 200-7, and the eighth symbol repeating unit 200-8.

The Walsh diffuser 300 includes a first Walsh diffuser 300-1, a second Walsh diffuser 300-2, a third Walsh diffuser 300-3, and a fourth Walsh diffuser 300-4. It is composed of

The summer 600 includes a first summer 600-1, a second summer 600-2, a third summer 600-3, and a fourth summer 600-4.

The switching controller 800 may switch a 1 × 2 switch 800-1 for switching data output from the first summer 600-1 and a data output from the second summer 600-2. 1 × 2 switch 800-2, 1 × 2 switch 800-3 for switching data output from the 1 × 2 switch 800-1, and 1 × 2 switch 800-2. 1 × 2 switch 800-4 for switching data outputted from the switch), and 2 × switching data output from the 1 × 2 switch 800-1 and 1 × 2 switch 800-3. 1x switch 800-5, 2x1 switch 800-6 for switching data output from the 1x2 switch 800-2 and 1x2 switch 800-4, and 1x. 2x1 switch 800-7 for switching data output from the second switch 800-3 and the third summer 600-3, and the 1x2 switch 800-4 and the 43th summer It consists of a 2x1 switch 800-8 which switches the data output from 600-4.

The complex PN spreader 400 receives the data output from the 2 × 1 switch 800-5 and the 2 × 1 switch 800-6, and outputs the data to the antenna. And a second complex PN diffusion unit 400-2 that receives data output from the 2 × 1 switch 800-7 and the 2 × 1 switch 800-8 and outputs the data to the antenna.

Referring to the operation of the transmission diversity configured as described above, the signal input to the demultiplexer 100 is passed through the symbol repeater 200, Walsh spreader 300 and summer 600 to the switching controller 800. Is entered.

The switching controller 800 determines whether to continuously use space time spread or transmit a signal to only one antenna according to a switching control command transmitted from the mobile station. 3, 800-4) (800-5, 800-6, 800-7, 800-8).

The method of selecting the switching control command and the switch control command from the mobile station is the same as in the case of FIG. 3, and the method of applying the weight is the same as in the case of FIG. 3.

Therefore, the proposed method in FIGS. 3 and 4 transmits a control command to transmit using one antenna having stable channel characteristics when one channel experiences severe fading, and in this case, weights only one path. As a result, since the signal is reconstructed, much diversity gain is obtained compared to the case of using orthogonal transmit diversity or space time spreading alone.

As described above, the present invention relates to whether the mobile station selectively uses both antennas or requests for signal transmission using only one antenna having a good channel environment according to the channel environment experienced by the signal transmitted from each antenna. The control command is transmitted, and the weight of the switch control command is applied differently to improve the performance of the forward link, and the transmission diversity method such as orthogonal transmit diversity and space time spreading which is applicable to the current IS-2000 system The advantage is that it is compatible without excessive changes.

In addition, since only the switching circuit is simply added, it is easy to implement and has the advantage of greatly improving the reliability of the system.

Claims (5)

A demultiplexer 100 which separates two pilot channels, a synchronization channel, a paging channel, and a traffic channel applied to the control input for each antenna to be transmitted; A symbol repeater (200) for receiving the channel data separated from each other by the demultiplexer (100) and repeatedly symbolizing the received channel data; A Walsh spreader (300) for receiving the symbolized data output from the symbol repeater (200) and multiplying the Walsh code to spread the multiplied Walsh code; A switching controller 700 determining which one of a plurality of antennas to transmit Walsh spread data output from the Walsh spreader 300; And a complex PN spreader (400) for receiving the data output from the switching controller (700) and spreading the pseudo noise code. The method of claim 1, The switching controller 700 receives Walsh spread data output from the Walsh spreader 300 and transmits even and odd bits to each of the two antennas, or only one antenna having a good channel environment among the two antennas. A device for transmission diversity, which determines whether to transmit a signal. The method of claim 1, The switching controller 700 includes 1 × 2 switches 700-1 and 700-2 for switching Walsh spread data output from the first Walsh spreader 300-1; 1 × 2 switches 700-3 and 700-4 for switching Walsh spread data output from the second Walsh spreader 300-2; A first summer 700-5 for summing data output by switching from the 1 × 2 switch 700-1 and the 1 × 2 switch 700-3; A second summer 700-6 for summing data output by being switched from the 1 × 2 switch 700-2 and the 1 × 2 switch 700-4; A 1 × 2 switch 700-7 for switching data output from the first summer 700-5; A 1 × 2 switch 700-8 for switching data output from the second summer 700-6; A 2 × 1 switch 700-9 for switching data output by being switched from the 1 × 2 switch 700-1 and 1 × 2 switch 700-7; A 2x1 switch 700-10 for switching data output by being switched from the 1x2 switch 700-2 and the 1x2 switch 700-8; A 2 × 1 switch 700-11 for switching data output from the 1 × 2 switch 700-3 and 1 × 2 switch 700-7; Transmission diversity control device, characterized in that consisting of the 2 × 1 switch 700-12 for switching the output data is switched from the 1 × 2 switch 700-4 and 1 × 2 switch 700-8 . A demultiplexer 100 which separates two pilot channels, a synchronization channel, a paging channel, and a traffic channel applied to the control input for each antenna to be transmitted; A symbol repeater (200) for receiving symbol data outputted separately from the demultiplexer (100) and repeatedly symbolizing the data; A Walsh spreader (300) for receiving the symbolized data output from the symbol repeater (200) and multiplying the Walsh code to spread the multiplied Walsh code; A summer 600 for receiving and summing Walsh spread data output from the Walsh spreader 300; A switching controller 800 which receives data output from the summer 600 and decides whether to use space time spreading or transmit a signal to only one antenna; And a complex PN spreader (400) for receiving data output from the switching controller (800) and spreading and converting the pseudo noise code to an antenna. The method of claim 4, wherein The switching controller 800 includes a 1 × 2 switch 800-1 for switching data output from the first summer 600-1; A 1 × 2 switch 800-2 for switching data output from the second summer 600-2; A 1 × 2 switch 800-3 for switching data output by being switched from the 1 × 2 switch 800-1; A 1 × 2 switch 800-4 for switching data output by being switched from the 1 × 2 switch 800-2; 2x1 switch 800-5 for switching data output from the 1x2 switch 800-1 and 1x2 switch 800-3; 2x1 switch 800-6 for switching data output from the 1x2 switch 800-2 and 1x2 switch 800-4; A 2x1 switch 800-7 for switching data output from the 1x2 switch 800-3 and the third summer 600-3; And a 2x1 switch (800-8) for switching data output from the 1x2 switch (800-4) and the 43th summer (600-4).