KR100379492B1 - Power control device of mobile communication system - Google Patents

Abstract

In particular, the present invention relates to a multicarrier direct spread CDMA type mobile communication system using a plurality of carriers, and predicts a plurality of low pass filter units and signals output from the low pass filter units. Outputs a plurality of transmission powers, and outputs a plurality of power prediction values through a plurality of multipath parts for outputting a plurality of arbitrary data for decoding, and a transmission power of a pilot channel and a traffic channel predicted by each multipath part. A power control predictor for multiplexing, a multiplexer for multiplexing a plurality of data for decoding output from the multipath unit, a decoder for decoding the multiplexed data in the multiplexer, and outputting a frame quality indicator from the decoded data; Power control using the frame quality indicator output from the decoder. An outer loop power control unit for outputting an arbitrary power control reference value for the control unit, and a power control reference value of each of the plurality of power prediction values output from the power estimating unit and the power control reference value of the outer loop power control unit, and outputs a large number of deviations accordingly A comparator and a power control bit generator for generating respective power control bits according to a plurality of deviations outputted from the comparator, are used for power control of a multicarrier direct spread CDMA type communication system using a plurality of carriers. A power control device of a suitable mobile communication system.

Description

Power control device of mobile communication system

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mobile communication system of a multicarrier direct spread CDMA scheme using a plurality of carriers, each subcarrier in a multipath channel environment for transmit diversity. The present invention relates to a power control apparatus of a mobile communication system capable of estimating a received power for and thus performing accurate power control.

In general, in a mobile communication system using a code division multiplex access (CDMA) method such as a cellular mobile communication system or a personal communication service, a plurality of mobile stations may be a base station or a cell site. Through this, a frame composed of symbols representing digitalized voice or other data is transmitted and received.

Such transmission frames are subject to fading through multipath, which is related to the characteristics of the transmission environment that reflects the transmission frame as the mobile station moves, or due to the high transmission power of a particular mobile station. It relates to interference characteristics in mobile station

In addition, if the mobile station uses too low transmit power, the base station receiving the transmitted frame may not be able to recover the data of the frame transmitted from the mobile station, which may result in data loss. In addition, the mobile station's frame transmit power is controlled for complete recovery of data transmitted while minimizing interference between mobile stations.

For the reasons described above, the base station transmits a power control bit to the mobile station to measure the transmit power from the frame transmitted at the mobile station and adjust the transmit power over each separate channel.

The power control bit is a transmit power increase bit or a transmit power decrease bit to maintain the average value of the received power. At this time, the base station controller (BSC) in charge of controlling the base station is optimal for maintaining the average value of the received power. Error rates are detected in the frame received from the mobile station to select the transmit power of < RTI ID = 0.0 >

1 is a view showing a part of the configuration of a mobile communication system using a CDMA scheme according to the prior art.

Referring to FIG. 1, a public switched telephone network (PSTN) is a communication network for general subscribers provided by a communication network operator, and the mobile subscribers use other mobile communication subscribers or general wired network subscribers using mobile communication services. A wired communication path is formed with a mobile switching center (MSC) 11 which performs circuit switching and relay call processing between subscribers so as to be able to make a call.

In addition, the base station controller (BSC) 12 is responsible for power control using the error rate of the received frame, so that the mobile station 13 transmits proper transmission power through the base station A 14A or the base station B 14B. Generate a power control command to send and receive data using.

Here, the power control command of the forward link is a power control increase bit or a power control decrease bit of 1 to 2 bits per frame transmitted.

2 is a block diagram showing a part of a power control apparatus of a mobile communication system using a CDMA scheme according to the prior art.

Referring to FIG. 2, a spread spectrum CDMA signal transmitted from a mobile station (not shown) is normally received by a reception antenna 20 of a base station through a CDMA channel, and the received CDMA signal is transmitted downward by the high frequency receiver 21. Frequency processing is performed.

In this case, the CDMA channel is usually composed of a pilot channel (Pilot ch), a synchronous channel (Synchronous ch), a paging channel (traffic ch), a traffic channel (Traffic ch) for forward access and communication from the base station to the mobile station, The CDMA channels are each orthogonally developed by 64 Walsh Function codes and then developed as orthogonal pairs of Pseudo Noise (hereinafter, abbreviated as PN) sequences at a fixed chip rate. Code symbolized.

In addition, a CDMA signal having various transmission rates is subjected to an encoding process in a mobile station (not shown), and is usually encoded into a frame having a 20 msec time interval. Here, the rate is 9.6 kbps (full rate), 4.8 kbps (half rate), 2.4 kbps (quarter rate), 1.2 kbps (eighth rate). Error Correcting Code is used.

The CDMA signal down-frequency processed by the high frequency receiver 21 is converted into a digital signal by the A / D converter 22, and the PN correlator 23 is provided by a PN code generator (not shown). The PN code is used to correlate the digitally converted CDMA signal.

The output of the PN correlator 23 is provided to the decoder 24 for decoding, and is also provided to the power predicting section 25 for predicting the average received power of the mobile station (not shown) that has transmitted the CDMA signal.

The decoder 27 decodes code symbols for the received CDMA signal and simultaneously provides the outer loop power control 26 with a frame quality indicator indicating the quality of the CDMA signal.

Accordingly, the outer loop power control unit 26 can know the transmission power sufficient for the mobile station (not shown) to transmit data, and provides the comparison unit 27 with a power control reference value to be used for power control of the forward link.

The comparison unit 27 compares the average value of the received power of the mobile station (not shown) predicted by the power predicting unit 25 with the power control reference value provided by the outer loop power control unit 26, and compares the power control reference value to the power control reference value. The deviation of the average received power value is provided to the power control bit generator 28.

The power control bit generator 28 provides the transmitter 29 with a received power increase bit or a received power decrease bit according to the deviation provided above.

The transmitter 29 transmits the received power increase bit or the received power decrease bit output from the power control bit generator 28 to the mobile station (not shown) together with the user data processed uplink with the transmission antenna 30. do.

Accordingly, the mobile station (not shown) adjusts the received power according to the received power increase / decrease command, and transmits the user data at the transmission rate accordingly.

In FIG. 2, power control through the power estimator 25, the comparator 27, and the power control bit generator 28 is referred to as closed loop power control. After measuring the received power according to the transmission rate of the signal, the base station compares the power control reference value preset for each base station, and sends the appropriate power control command to the mobile station along with user data. According to the transmission power adjusted according to the power control.

Here, in performing the closed loop power control, a different power control reference value is set for each mobile station according to various parameters such as the moving speed of the mobile station, the environment of the mobile station, and the like. The power control reference value is adjusted according to the received data frame error rate. Such power control is called outer loop power control.

In the mobile communication system using the CDMA system according to the prior art, the power control apparatus transmits power of each mobile station to the base station with a minimum signal-to-interference ratio so that the maximum number of mobile stations that can simultaneously talk within a given bandwidth. Designing to reach is very important.

In addition, recently, a multicarrier direct spread CDMA communication system using a plurality of carriers for signal transmission has been proposed, which requires the most appropriate power control.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is suitable for power control of a multicarrier direct spread CDMA communication system using a plurality of carriers. An object of the present invention is to provide a power control device of a mobile communication system that performs independent power control with respect to the.

A feature of the power control apparatus of the mobile communication system according to the present invention for achieving the above object is to transmit arbitrary data spread directly by using a plurality of carriers having different frequencies, and to receive the transmitted data In a communication system of a multicarrier direct spread CDMA system generating an arbitrary power control command as many as the carrier number, a plurality of low pass filter units and a plurality of transmit powers estimated from respective signals output from the low pass filter units are used. A plurality of multipath parts for outputting a plurality of arbitrary data for decoding, and a power control prediction for outputting a plurality of power prediction values through transmission powers of pilot channels and traffic channels predicted in each multipath part. Section and multiplexing data for decoding output from the multipath section. Outputting an arbitrary power control reference value for power control using a multiplexer, a decoder for decoding the data multiplexed in the multiplexer, outputting a frame quality indicator from the decoded data, and a frame quality indicator output from the decoder And a comparison unit for comparing a plurality of power prediction values output from the power prediction unit and a plurality of power control reference values of the outer loop power control unit, and outputting a large number of deviations. And a power control bit generator for generating each power control bit according to a plurality of deviations.

Preferably, the plurality of multipath units each include a pseudo noise correlator for correlating with the received signal using a pseudo noise code provided from an external device, and a pilot carried on a channel environment among the outputs of the pseudo noise correlator. A phase predictor for correcting the phase of the data channel by using a signal and orthogonally outputting the output of the pseudo noise correlator by using a channel predictor for predicting and outputting the transmission power included in the received power of the pilot signal and a Walsh code provided from the outside. From a first multiplier for expanding, a accumulator for accumulating the output of the first multiplier, a second multiplier for combining the output of the channel predictor and the output of the accumulator, and an output of the second multiplier It consists of an eye / cue multiple part for outputting a single signal having an arbitrary frequency and phase equal to each other.

1 is a diagram showing a part of a configuration of a mobile communication system using a CDMA scheme according to the prior art.

2 is a block diagram showing a part of a power control device of a mobile communication system using a CDMA scheme according to the prior art;

3 is a block diagram showing the configuration of a transmitter for power control in a multicarrier direct spread CDMA communication system using multiple carriers in accordance with the present invention;

4 is a block diagram showing the configuration of a power control device of a multicarrier direct spread CDMA communication system using multiple carriers according to the present invention;

Explanation of symbols for main parts of the drawings

610, 710, 810: PN correlator 620, 720, 820: channel predictor

640, 740, 840: Accumulator 650, 750, 850: I / Q Multiple

490: power prediction unit 500: comparison unit

510: power control bit generator

Hereinafter, a preferred embodiment of a power control device of a mobile communication system according to the present invention will be described with reference to the accompanying drawings.

3 is a block diagram illustrating a configuration of a transmitter for power control of a multicarrier direct spread CDMA communication system using multiple carriers according to the present invention.

Referring to FIG. 3, the transmitter can be applied to both the forward and reverse links, and transmits data using a plurality of N subcarriers. As such, when multiple carriers are used, diversity effects can be obtained in a multipath channel environment.

Since the signal is spread in each carrier and the frequency band for each carrier is relatively wide, the channel environment for all carriers cannot be the same. Due to the deterioration of the channel environment, the power of the transmission signal included in the received signal may be relatively lower than the power of other carriers in some carrier frequency parts, resulting in a decrease in overall performance.

In particular, in case of using transmit diversity using multiple antennas in the transmission end, independent power control is required because the channel environment of the carrier waves from each antenna is different.

The encoder 100 encodes the transmission data to be transmitted by the mobile station, and the demultiplexer 110 transmits the encoded signals to perform transmission diversity using a plurality of antennas (not shown). The application data is demultiplexed through multiple paths with different channel environments.

The multiplexed data is transmitted to the outside by different carriers (Carrier 1 to Carrier N) according to each path through multiple paths having different channel environments.

Each path having a different channel environment has the same configuration, and only different frequencies of carriers used.

Hereinafter, a detailed description of any one of the multi-path is as follows.

The serial-to-parallel converter 120 outputs an I signal and a Q signal having the same frequency and a phase difference of 90 degrees from each other by inputting one data among a plurality of inverse multiplexed data. The I signal and the Q signal which are converted in parallel in parallel and output are orthogonally developed by the Walsh code in the first multiplier 130 and the second multiplier 140, respectively, and are output as code symbols.

Each code symbol that is previously output is spread using a Pseudo Noise Code (hereinafter, abbreviated as PN code) in the PN spreader 150, and the two pre-spread code symbols are respectively baseband filter units. Via (160,170).

The third multiplier 180 and the fourth multiplier 190 multiply subcarriers having different phases with respect to the signals output from the baseband filter units 160 and 170, respectively. Each signal multiplied by carriers of different phases is summed by the adder 200 to output a carrier including data for transmission through a multipath channel environment.

In the apparatus for forward or reverse link transmission of a direct spread CDMA communication system using a plurality of carriers (Carrier 1 to Carrier N), the transmission power of a subcarrier multiplied by each multiplier is forward. Or controlled independently by power control bits input through the reverse link, and power control bits are inserted and sent for each subcarrier.

4 is a block diagram showing the configuration of a power control apparatus of a multicarrier direct spread CDMA communication system using multiple carriers according to the present invention.

Referring to FIG. 4, in a receiving apparatus that receives a signal transmitted from a transmitting apparatus of a direct spread CDMA communication system using three carriers in FIG. 3, the band pass filter 400 spreads the spectrum from the transmitting apparatus. Only the signal of the same frequency band as the transmitted signal is passed, and the output is divided into the I channel and the Q channel signal to pass the respective paths.

The output signal of the band pass filter unit 400 is the sum of the signals carried on the N carriers, the first multiplier 410 and the second multiplier 420 in order to recover the signals carried on each carrier, After multiplication, the output signal is provided to each of the low pass filter sections 430, 440, and 450.

The PN correlators 610, 710, and 810 of the multipath are correlated with the signals output from the low pass filter units 430, 440, and 450 using the PN codes provided by the PN code generator (not shown).

Each correlation value output from the PN correlators 610, 710, and 810 is input to the channel predictors 620, 720, and 820, respectively, to correct the phase of the traffic signal on the traffic channel using the pilot signal received through the pilot channel. The transmission power included in the reception power of the received pilot signal is predicted, respectively. At the same time, each output correlation value is input to the third multipliers 630, 730, and 830, respectively, and is orthogonally developed by the Walsh code.

In addition, the accumulators 640, 740, and 840 accumulate signals that are orthogonally developed through the third multipliers 630, 730, and 830, respectively.

In this case, the outputs of the channel predictors 620, 720, 820 and the outputs of the accumulators 640, 740, 840 are combined and combined with the I and Q signals to be input to the I / Q multiplexers 650, 750, 850 and the I / Q multiplexers 650, 750, 850. ) Outputs a single signal from I and Q signals having different phases.

The outputs of the channel predictors 620, 720, 820 and the outputs of the accumulators 640, 740, 840, respectively, through the multipath channel environment are also provided to the power predictor 490, and the power predictor 490 is a channel predictor 620, 720, 820. ) And the power prediction values as many as the number of carrier paths are output from the outputs of the accumulators 640, 740, 840.

The output of each I / Q multiplexer 650, 750, 850 is multiplexed in the multiplexer 460 and decoded by the decoder 470.

The decoder 470 provides a frame quality indicator to the outer loop power control unit 480, and the outer loop power control unit 480 outputs a power control reference value using the provided frame quality indicator.

The comparator 500 compares the power predicted value of the number of carrier paths output from the power predicting unit 490 with the power control reference value output from the outer loop power control unit 480, respectively, and compares the deviation with the power control bit generator. Output to 510.

The power control bit generator 510 generates the power control bits as many as the number of carrier paths using the previously output deviations, and transmits them through the transmitter 520.

As a result, the power for transmitting the transmission data can be adjusted according to the power control bits as many as the number of carrier paths generated through the multipath channel environment.

According to the present invention, since independent power control can be performed for each carrier used for a multipath channel according to transmission diversity, power of a multicarrier direct spread CDMA communication system using a plurality of carriers. It is suitable for control and has the effect of further improving the performance of the communication system.

Claims (2)

Multicarrier direct spread CDMA communication in which arbitrary data spread directly by using a plurality of carriers having different frequencies is transmitted, and receiving the transmitted data to generate an arbitrary power control command as many as the carrier number. In the system, A plurality of low pass filter units; A plurality of multipath units for outputting a plurality of transmission powers predicted from the respective signals output from the low pass filter unit and for outputting a plurality of arbitrary data for decoding; A power control predicting unit for outputting a plurality of power prediction values through the transmission powers of the pilot channel and the traffic channel predicted by each of the multipath units; A multiplexer for multiplexing data for decoding, which is output from the multipath unit; A decoder for decoding the data multiplexed by the multiplexer and outputting a frame quality indicator from the decoded data; An outer loop power control unit for outputting an arbitrary power control reference value for power control using a frame quality indicator output from the decoder; A comparison unit for comparing each of the plurality of power prediction values output from the power prediction unit with the power control reference value of the outer loop power control unit, and outputting a plurality of deviations accordingly; And a power control bit generator for generating each power control bit according to a plurality of deviations output from the comparison unit. The method of claim 1, wherein the plurality of multipath portions are each A pseudo noise correlator for correlating the received signal using a pseudo noise code provided from an external device; A channel predictor for correcting a phase of a data channel by using a pilot signal on a corresponding carrier among the outputs of the pseudo noise correlator, and for predicting and outputting transmission power included in received power of the pilot signal; A first multiplier for orthogonally expanding the output of the pseudo noise correlator using an externally provided Walsh code; An accumulator for accumulating the output of the first multiplier; A second multiplier for mutually coupling the output of the channel predictor and the output of the accumulator; And an eye / cue multiple part for outputting a single signal having an arbitrary frequency and phase equal to each other from the output of the second multiplier.