KR20010107139A - Appartus for controlling forward link power applied orthogonal transmit diversity in mobile communication system - Google Patents

Abstract

The present invention relates to a forward link power control apparatus of a mobile communication system capable of efficiently controlling the pilot channel power strength of transmission diversity used to increase the capacity of a forward link in a mobile communication system. After multiplying the input multi-channel signal by antenna and performing symbol repetition process, multiply different Walsh codes to give orthogonality to each antenna and spread-modulate it by pseudo-noise code. Detects a pilot channel for orthogonal transmission diversity among signals transmitted through the antenna of the base station and the base station, compares the strength with an existing pilot channel, determines the power control bit according to the result, and inserts the power control bit to transmit the signal to the base station. It consists of a mobile station.

Description

Applied for controlling forward link power applied orthogonal transmit diversity in mobile communication system}

The present invention relates to a power control device of a next generation mobile communication system, and more particularly, to efficiently control pilot channel power strength for orthogonal transmit diversity used to increase capacity of a forward link in a mobile communication system. The present invention relates to a forward link power control device of a mobile communication system.

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, IS-95A systems currently in service have gained diversity gain by using two receive antennas to improve the performance of reverse link power.

However, using two mobile station antennas to obtain diversity gain of the forward link power not only increases the size of the mobile station but also causes an increase in cost by using two receivers.

Accordingly, the present invention has been made to solve the above-described problems according to the prior art. The object of the present invention is to measure the quality of the forward link signal by using a pilot channel on the reverse link, unlike the IS-95A system. The base station transmits the power control bits, and the base station examines the power control bits of the reverse pilot channel and adjusts the power of the pilot channel for the forward link orthogonal transmit diversity to increase the capacity of the forward link. The present invention provides a forward link power control apparatus for a communication system.

A feature of the forward link power control apparatus of the mobile communication system according to the present invention for achieving the above object is to separate the transmitted multi-channel signal by antenna to perform a symbol repetition process and then to give orthogonality to each antenna by different Walsh After multiplying the code, spread-transforming the pseudo-noise code, and shifting the modulation, the base station transmits an ideal component and an in-phase component to the antenna, and detects a pilot channel for orthogonal transmission diversity among signals transmitted through the antenna of the base station. And the power control bit is determined according to the result, and then the power control bit is inserted and transmitted to the base station.

1 is a block diagram showing a forward link power control apparatus of a mobile communication system base station having an orthogonal transmit diversity function according to the present invention;

2 is a block diagram of a mobile station for generating power control information for controlling signal power of a forward link by measuring the strength of a pilot channel for orthogonal transmit diversity output from a base station apparatus having an orthogonal transmit diversity function according to the present invention. It is also.

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

10: demultiplexer, 12: symbol repeater,

14: Walsh diffusion unit, 16: PN diffusion unit,

18: modulator, 20: summer,

30: lake receiving unit, 32: pilot channel detection unit,

34: decoding unit, 36: power control bit determining unit,

38: Power control bit insertion section.

Hereinafter, a preferred embodiment of a forward link power control apparatus of a mobile communication system using orthogonal transmit diversity according to the present invention will be described with reference to the accompanying drawings.

1 is a block diagram showing a forward link power control apparatus of a mobile communication system base station having an orthogonal transmit diversity function according to the present invention.

As shown in FIG. 1, a demultiplexer 10 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 10. A symbol repeater 12 that receives the data outputted separately from each other and symbolizes the symbol repeatedly, and a Walsh that multiplies the Walsh code by receiving the symbolized data output from the symbol repeater 12. PN spreader 16, which receives Walsh spread data output from Walsh spreader 14, and spreads and converts it into a pseudo noise code, and pseudo noise output from PN spreader 16. A modulator 18 for quadrature phase shift keying (QPSK) receiving the code, and a quadrature phase-modulated quadrature component and in-phase component outputted from the modulator 18; in-phase components Combiner 20 is configured to transmit to the antenna.

The symbol repeater 12 may include a first symbol repeater 12-1, a second symbol repeater 12-2, a third symbol repeater 12-3, and a fourth symbol repeater 12-4. It is composed of

The Walsh diffuser 14 includes a first Walsh diffuser 14-1 and a second Walsh diffuser 14-2.

The PN diffusion unit 16 includes a first PN diffusion unit 16-1 and a second PN diffusion unit 16-2.

The modulator 18 includes a first modulator 18-1, a second modulator 18-2, a third modulator 18-3, and a fourth modulator 18-4.

The summer 20 includes a first summer 20-1 and a second summer 20-2.

2 is a block diagram of a mobile station generating power control information for controlling signal power of a forward link by measuring the strength of a pilot diversity channel output from a base station apparatus having an orthogonal transmit diversity function according to the present invention; to be.

As shown in FIG. 2, the rake receiver 30 receives and separates the signals transmitted through the antennas (first antenna and second antenna) of the base station into different wireless channels, and from the rake receiver 30. Decoding the signal through a process of demodulating and combining the signals output from the pilot channel detector 32 and the rake receiver 30 to detect the pilot channel for the orthogonal transmission diversity of the corresponding base station among the different radio channels outputted. The intensity of the orthogonal transmit diversity pilot channel output from the decoder 34 and the pilot channel detector 32 is measured, and the strength of the orthogonal transmit diversity pilot channel signal and the intensity of the existing pilot channel signal are measured. In comparison, when the strength of the pilot channel signal for orthogonal transmit diversity is smaller or greater than a predetermined level, the pilot channel power control of the reverse pilot channel is performed. A power control bit determiner 36 which determines a bit as "0" or "1", and a power control bit inserter 38 which inserts the power control bit determined by the power control bit determiner 36 and transmits it to the base station It is composed of

The operation of the forward link power control apparatus of the mobile communication system applying the orthogonal transmit diversity configured as described above is as follows.

First, a pilot channel, a synchronization channel, a paging channel, and a traffic channel are input to the demultiplexer 10, and the demultiplexer 10 separates the input channels into two antennas for each antenna to be transmitted, and the first symbol repeater 12 -1), the second symbol repeating unit 12-2, the third symbol repeating unit 12-3, and the fourth symbol repeating unit 12-4.

The first symbol repeater 12-1 and the second symbol repeater 12-2 repeatedly symbolize the transmitted channels and transmit the channels to the first Walsh spreader 14-1.

In addition, the third symbol repeater 12-3 and the fourth symbol repeater 12-4 repeatedly symbolize the transmitted channels and transmit the channels to the second Walsh spreader 14-2. .

In this case, the first Walsh spreader 14-1 and the second Walsh spreader 14-2 multiply different Walsh codes to give orthogonality to the symbolized channels and multiply the data.

The first Walsh spreader 14-1 and the second Walsh spreader 14-2 transmit the output data to the first PN spreader 16-1 and the second PN spreader 16-2, respectively. send.

The first PN spreader 16-1 and the second PN spreader 16-2 spread the transmitted data into a pseudo noise code, and spread the pseudo noise code into a first modulator 18-1 and a second modulator. (18-2), the third modulator 18-3 and the fourth modulator 18-4.

Here, the first modulator 18-1, the second modulator 18-2, the third modulator 18-3, and the fourth modulator 18-4 are four-phase shift modulators (QPSK). quadrature phase shift keying).

The first modulator 18-1 and the second modulator 18-2 modulate the four-phase shift of the transmitted pseudo noise code and transmit the modulated four-phase shift to the first summer 20-1.

In addition, the first modulator 18-3 and the second modulator 18-4 modulate the four-phase shift of the transmitted pseudo noise code and transmit the modulated four-phase shift to the second summer 20-2.

In addition, the first summer 20-1 and the second summer 20-2 add the transmitted four-phase shift modulation abnormal components and in-phase components to the first antenna and the second antenna.

On the other hand, the signal transmitted to the first antenna and the second antenna of the base station passes through different radio channels and transmits it to the rake receiver 30, the pilot channel detector 32 and the decoder 34 of the mobile station.

Here, the decoder 34 decodes the transmitted signals by demodulating and combining them.

In addition, the pilot channel detector 32 detects a pilot channel for orthogonal transmit diversity of the base station among the transmitted signals and transmits the pilot channel to the power control bit determiner 36.

At this time, the power control bit determiner 36 compares the strengths of the pilot channel signals for the orthogonal transmit diversity with the strengths of the existing pilot channel signals, and the strength of the orthogonal transmit diversity pilot channel signal is smaller than a predetermined level. If large, the pilot channel power control bit of the reverse pilot channel is determined as "0" or "1" and transmitted to the power control bit inserter 38.

In addition, the pilot channel signal of the mobile station needs to add a separate pilot channel power control bit in addition to the existing power control bit for pilot channel power control for orthogonal transmit diversity.

The power control bit inserter 38 inserts the power control bit determined by the power control bit determiner 36 and transmits the inserted power control bit to the base station.

Accordingly, the base station detects a power control bit in the received signal to determine whether to increase or decrease the pilot channel power level for orthogonal transmit diversity.

As described above, when using orthogonal transmit diversity, a separate pilot channel for orthogonal transmit diversity is required together with an existing pilot channel signal in order to demodulate two transmitted signals at a mobile station. Provides the synchronization necessary for the mobile station to demodulate the received signal.

In addition, since the capacity of the forward link is mainly determined by the power allocation used in each channel and the degree of interference according to the power strength of each channel, it is important to appropriately distribute the power of each channel to minimize the interference between each channel.

That is, since a separate pilot channel for orthogonal transmit diversity is required, the power level of the additional channel of the forward link increases.

At this time, the interference of other channels is increased by the increased power, and a substantial part of the transmission gain generated by using orthogonal transmission diversity is attenuated.

As described above, the present invention is used to improve the performance of a forward link operating in a direct spread scheme, and by transmitting a single signal through two paths, even if one signal experiences severe fading, the effects of fading are relatively high. The signal that receives less is compensated for the effect during the demodulation process, thereby improving the performance of the forward link.

Claims (3)

a) separates and transmits the input multi-channel signal for each antenna and performs symbol repetition b) multiply different Walsh codes to give orthogonality for each antenna; c) a base station for spread-transforming a pseudo-noise code by shift-modulating and combining an abnormal component and an in-phase component to an antenna; a) detecting a pilot channel for orthogonal transmit diversity among signals transmitted through the antenna of the base station; b) compare the strength with the existing pilot channel, c) determine the power control bit according to the result, d) A forward link power control apparatus of a mobile communication system using orthogonal transmit diversity, comprising: a mobile station inserting a power control bit and transmitting the same to a base station. The method of claim 1, The base station includes a demultiplexer for separating two antennas to be transmitted from a channel applied to a control input; A symbol repeater which repeatedly receives and outputs data outputted separately from the demultiplexer two times; A Walsh spreader configured to receive the symbolized data output from the symbol repeater and multiply the Walsh code to spread the multiplied Walsh code; A PN spreader which receives Walsh spread data output from the Walsh spreader and spreads the pseudo noise code into a pseudo noise code; A modulator configured to receive a pseudo-noise code outputted from the PN spreader and to modulate the four-phase shift of the phase; Four-phase shifted quadrature component and in-phase component outputted from the modulator is combined with an adder for transmitting to the antenna forward direction of the mobile communication system applying the orthogonal transmission diversity Link power control device. The method of claim 3, wherein The mobile station includes a rake receiver for separating and receiving signals transmitted through the antenna of the base station into different radio channels; A pilot channel detector for detecting a pilot channel for orthogonal transmit diversity of a corresponding base station among different radio channels output from the rake receiver; A decoder which decodes the signal through a process of demodulating and combining the signals output from the rake receiver; The strength of the orthogonal transmit diversity pilot channel signal output from the pilot channel detector is measured and the strength of the orthogonal transmit diversity pilot channel signal is compared with that of the existing pilot channel signal. A power control bit determining unit for determining a pilot channel power control bit of the reverse pilot channel when the value is smaller than or greater than a predetermined level; And a power control bit inserting unit inserting the power control bit determined by the power control bit determining unit and transmitting the inserted power control bit to the base station.