KR20080060894A - Method for controlling power of td-scdma system and apparatus applied to the same - Google Patents

Abstract

A method for controlling power in a TD-SCDMA(Time Division-Synchronous Code Division Multiple Access) system and an apparatus applied to the same are provided to verify the reliability of a TPC(Transmit Power Control) bit using channel estimation information in decoding the TPC bit, thereby improving the performance of signal reception by controlling transmission power. A method for controlling power in a TD-SCDMA system comprises the following steps of: demodulating a radio signal received through an antenna and converting the received radio signal into a baseband signal(S100); separating a midamble signal from the converted radio signal(S200); producing a channel impulse response through channel estimation based on the separated midamble signal(S300); extracting a user data signal and a TPC bit based on the produced channel impulse response(S400); and controlling the power of a transmission signal according to the size of the produced channel impulse response and the TPC bit(S500).

Description

TECHNICAL FOR CONTROLLING POWER OF TD-SCDMA SYSTEM AND APPARATUS APPLIED TO THE SAME

1 illustrates a structure of a data slot for forward or reverse data transmission in a TD-SCDMA system.

2 is a diagram illustrating a transmission power control bit and its meaning according to a modulation scheme defined in the prior art 3GPP.

3 is a schematic structural diagram of a transceiver in which power control operation is implemented in a TD-SCDMA system according to an embodiment of the present invention;

4 is a flowchart illustrating a power control method in a TD-SCDMA system according to an embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

100: transceiver module 110: antenna

200: demodulator 300: demultiplexer (DeMUX)

400: midamble detector

500: Channel Estimator

600: Joint Detector

700: power controller (TPC Decision)

The present invention verifies the reliability of transmission power control bits using channel estimation information in decoding transmission power control bits in a TD-SCDMA system. The present invention relates to a power control method and apparatus applied thereto in TD-SCDMA for improving reception performance due to power control.

In general, the TD-SCDMA system has three major characteristics compared to the WCDMA and CDMA 2000 systems in the frequency division duplex mode.

First, it is suitable for asymmetric services. Since the frequency division duplex scheme employed by the WCDMA and CDMA 2000 systems allocates a fixed frequency band for forward / reverse data transmission, the mobile Internet has asymmetric data traffic between forward and reverse directions. Wireless resources cannot be used efficiently when providing services such as However, since the TD-SCDMA technology controls the forward and reverse slot units, the number of forward and reverse transmission slots can be adaptively adjusted according to the amount of traffic, which is effective for asymmetric data transmission.

In addition, the second feature is that it is easy to change from the existing second generation mobile communication system to the third generation mobile communication system. The TD-CDMA standard has a 1.6 MHz carrier band, allowing for the addition of TD-CDMA systems to second-generation mobile networks such as GSM and IS-95 for band use and wireless network design, reducing initial investment and ensuring stability. can do.

In addition, the third characteristic is that the frequency efficiency is improved by introducing a joint detection technique, a precise forward synchronization technique of the terminal, a smart antenna, and dynamic channel allocation. In practice, smart antenna technology has been considered to be introduced in other 3G mobile communication systems, and thus it may be difficult to consider it as an advantage of TD-SCDMA, but combined detection and terminal synchronization are considered unique technologies of TD-SCDMA.

In this regard, Figure 1 shows the structure of a data slot for forward or reverse data transmission in a TD-SCDMA system.

As shown in FIG. 1, data slots in a TD-SCDMA system are used to transmit TFCI field information required for higher data transmission, transmit TPC (Transmit Power Control) information for power control, and SS (Synchronization) for timing synchronization. Shift) information is included in the data symbol period. Here, the TPC field transmits power control information for requesting to increase or decrease the transmit power of the transmitter based on the reception level of each currently received signal. More specifically, in the TD-SCDMA system, the forward base station transmission signal and the uplink terminal transmission power are controlled in units of 5 ms long subframes, and data transmission adjacent to the midamble of the time slot for each mobile terminal user in the subframe is performed. Transmit power control is performed at the transmitting end by transmitting parts by replacing them with control bits. In this regard, FIG. 2 shows a table showing transmission power control bits and their meanings according to the modulation scheme defined in the conventional 3GPP.

That is, when QPSK coding is used, the transmission power is decreased when '00' is used for two symbols, and when the '11', the transmission power is increased. Similarly, when 8PSK coding is used, the transmission power is decreased when '000' is used for three symbols, and when the '110', the transmission power is increased.

However, the transmitted power control bits are simply transmitted twice in the case of using the QPSK modulation scheme and do not use channel coding considering the radio environment such as attenuation and fading.

That is, the data bits have a constant coding rate according to the transmission rate and use a high performance convolutional code or a turbo code, whereas the transmission power control bits use a simple double repetition code, and thus the reception performance is relatively weak. Therefore, when the situation of the wireless channel is bad, errors are likely to occur in the transmission power control bits, which may cause continuous radio reception performance degradation.

Accordingly, the present invention has been made to solve the above problems, and an object of the present invention is to verify the reliability of transmission power control bits using channel estimation information in decoding transmission power control bits in a -SCDMA system. Separating the midamble signal from the radio signal received through the antenna, calculating a channel impulse response through channel estimation based on the separated midamble signal, and based on the calculated channel impulse response user data signal and The present invention provides a power control method in a TD-SCDMA system that extracts a power control bit (TPC) and controls power of a transmission signal according to the magnitude of the calculated impulse response and the power control bit.

In addition, another object of the present invention for solving the above problems, the size of the channel impulse response calculated through the channel estimation for obtaining the user data from the midamble signal included in the radio signal in the TD-SCDMA system The present invention provides a power control apparatus in a TD-SCDMA system that compares a predetermined setting value and controls power of a transmission signal based on the comparison result and the power control bits extracted from the channel impulse response.

In accordance with an aspect of the present invention for achieving the above object, there is provided a power control method in a Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) system: Separating the midamble signal from the wireless signal received through the antenna; b) calculating a channel impulse response through channel estimation based on the separated midamble signal; c) extracting a user data signal and a transmit power control (TPC) based on the calculated channel impulse response; And d) controlling power of a transmission signal according to the magnitude of the impulse response calculated through step 'b)' and the power control bit.

In the above configuration, the step a) comprises: a-1) demodulating and converting the radio signal received through the antenna into a baseband; And a-2) separating the midamble signal from the radio signal changed into the base band.

In the above configuration, step b) is characterized in that for calculating the channel impulse response through ML (Maximum Likelihood) estimation.

In the above configuration, the step d) may include: when the calculated magnitude of the impulse response is larger than a predetermined set value, the transmission corresponding to the increase, hold, and decrease control operations of the transmission signal power according to the power control bit, respectively. Increase, maintain and decrease the power of the signal.

In the above configuration, step d) corresponds to an increase or retention control operation of the transmission signal power according to the power control bit when the magnitude of the calculated impulse response is smaller than a predetermined set value. It is characterized by increasing the.

In the above configuration, step d) corresponds to a control operation for reducing the power of the fraudulent transmission signal according to the power control bit when the magnitude of the calculated impulse response is smaller than a predetermined setting value. It is characterized by maintaining.

In the above configuration, step d) is characterized in that when the magnitude of the calculated impulse response is smaller than a predetermined value, the power of the transmission signal is maintained regardless of the power control bit.

According to another aspect of the present invention, there is provided a power control apparatus in a Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) system, the apparatus comprising: a midamble included in a radio signal; Comparing the magnitude of the channel impulse response calculated through channel estimation for acquiring user data from the signal with a predetermined value, and controlling the power of the transmission signal based on the comparison result and the power control bits extracted from the channel impulse response. It is characterized by.

In the above configuration, when the calculated magnitude of the impulse response is larger than the predetermined set value, the power of the transmission signal is increased in response to the increase, hold, and decrease control operations of the transmission signal power according to the power control bit, respectively. , Maintenance and reduction.

In the above configuration, when the calculated magnitude of the impulse response is smaller than the predetermined value, the power of the transmission signal is increased in response to the increase or maintenance control operation of the transmission signal power according to the power control bit. It is done.

In the above configuration, when the calculated magnitude of the impulse response is smaller than a predetermined value, the power of the transmission signal is maintained in response to a control operation for reducing the power of the fraudulent transmission signal according to the power control bit. .

In the above configuration, when the calculated magnitude of the impulse response is smaller than the predetermined value, the power of the transmission signal is maintained regardless of the power control bit.

According to yet another aspect of the present invention, there is provided a power control apparatus in a Time Division-Synchronous Code Division Multiple Access (TD-SCDMA) system, comprising: a radio received via an antenna A demodulator for demodulating the signal and converting the signal into a baseband signal; A midamble signal detector for separating a midamble signal from the baseband radio signal output from the demodulator; A channel estimator receiving the separated midamble signal and performing channel estimation to calculate a channel impulse response; A combined detector for receiving the calculated channel impulse response and extracting user data and power control bits; And a power controller controlling power of a transmission signal based on the calculated magnitude of the channel impulse response and the extracted power control bits.

In the above configuration, the channel estimator calculates the channel impulse response through ML (Maximum Likelihood) estimation.

In the above configuration, when the magnitude of the calculated impulse response is larger than a predetermined set value, the power controller corresponds to the increase, hold, and decrease control operations of the transmit signal power according to the power control bits, respectively. It is characterized by increasing, maintaining and reducing the power of.

In the above configuration, when the magnitude of the calculated impulse response is smaller than a predetermined set value, the power controller increases the power of the transmission signal in response to an increase or maintenance control operation of the transmission signal power according to the power control bit. It is characterized by increasing.

In the above configuration, when the magnitude of the calculated impulse response is smaller than a predetermined set value, the power controller maintains the power of the transmission signal in response to a control operation for reducing the power of the fraudulent transmission signal according to the power control bit. It is characterized by.

In the above configuration, when the magnitude of the calculated impulse response is smaller than a predetermined set value, the power controller maintains the power of the transmission signal regardless of the power control bit.

(Example)

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a structure of a transceiver that implements a power control operation in a time division-synchronous code division multiple access (TD-SCDMA) system according to an embodiment of the present invention.

As shown in FIG. 3, the transceiver has a configuration including a receiving end A for detecting user data from a wireless signal input from the outside and a transmitting end B for receiving and transmitting user data wirelessly. The receiving end (A) is a radio transceiver module 100, a demodulator (Demodulation, 200), demultiplexer (DeMUX, 300), a midamble signal detector (Midamble Detector, 400), a channel estimator (500), combining It has a configuration including a detector (Joint Detector, 600), and a power controller (TPC Decision, 700).

The demodulator 200 demodulates the radio signal received through the radio transceiver module 100 including the antenna 110 and converts the radio signal into a baseband signal.

The midamble signal detector 400 receives the baseband radio signal output from the demodulator 200 through the demultiplexer 300 and separates the midamble signal. For reference, the separated midamble signal is used for distinguishing a terminal using the same timeslot for uplink transmission or for identifying downlink channels using the same timeslot, and also used for channel estimation in uplink and downlink transmission. In measuring the loss according to the channel path from the base station to the terminal, or is used to distinguish the base station because each base station uses a different midamble.

The channel estimator 500 receives the separated midamble signal through the midamble signal detector 400 and calculates a channel impulse response. Preferably, the channel estimator 500 calculates the channel impulse response through Maximum Likelihood (ML) estimation.

Looking at the operation of the channel estimator 500 in more detail, the vector matrix consisting of the mid-mambles of the users constituting one cell as 'Ｇ', the impulse response vector of the radio channel to 'ｈ', the noise vector on the channel When expressed as 'n', the received signal vector 'e' may be expressed as Equation 1> below.

Equation 1>

Furthermore, the channel estimator 500 assumes that the noise is white noise and calculates the channel impulse response through the ML (Maximum Likelihood) estimation as shown in Equation 2 below.

Equation 2

The coupling detector 600 receives the channel impulse response calculated from the channel estimator 500 and extracts user data and power control bits. Preferably, the combination detector 600, based on the channel impulse response, a user data signal and a transport format combination indicator (TFCI), power control bits (TPC, Transmit Power Control), and SS (Synchronization) Perform joint detection for (Shift).

The power controller 700 controls the power of the transmission signal based on the magnitude of the channel impulse response calculated by the channel estimator 500 and the power control bits extracted by the coupling detector 600. That is, the power controller 700 compares the magnitude of the channel impulse response with a predetermined set value, and controls the power of the transmission signal based on the comparison result and the power control bits extracted from the channel impulse response.

Preferably, when the magnitude of the calculated impulse response is larger than the predetermined value, the power controller 700 corresponds to the increase, hold, and decrease control operations of the transmission signal power according to the power control bit. Increase, maintain and decrease the power of the transmitted signal. That is, if the channel impulse response is sufficiently large, the conventional power control scheme of adjusting the transmission power according to the power control bit is maintained as it is.

However, if the calculated magnitude of the impulse response is smaller than the predetermined set value, the power controller 700 according to the present invention increases the transmit signal power of the power control bit even if the power control bit instructs to maintain the transmission signal power. Equally increase the transmit signal power. In addition, when the calculated magnitude of the impulse response is smaller than the predetermined value, the power controller 700 according to the present invention maintains the state of the transmit signal power even if the power control bit indicates a decrease in the transmit signal power.

On the other hand, if the magnitude of the calculated impulse response is smaller than the predetermined value, the power controller 700 may determine that the power control bit is unreliable, and may be implemented to maintain the transmission power regardless of the power control bit.

Hereinafter, a power control method in a TD-SCDMA system according to an embodiment of the present invention will be described with reference to FIG. 4. 4 is a flowchart illustrating a power control method in a TD-SCDMA system according to an embodiment of the present invention.

First, demodulating the radio signal received through the antenna to convert to the base band (S100). That is, the demodulator 200 demodulates the radio signal received through the radio transceiver module 100 including the antenna 110, converts the radio signal into a baseband signal, and outputs the demodulated signal.

Next, the midamble signal is separated from the radio signal changed into the base band (S200). That is, the midamble signal detector 400 receives the baseband radio signal output from the demodulator 200 through the demultiplexer 300 and separates the midamble signal.

Then, a channel impulse response is calculated through channel estimation based on the separated midamble signal (S300). That is, the channel estimator 500 calculates the channel impulse response through maximum likelihood (ML) estimation.

Thereafter, the user data signal and the power control bit are extracted based on the calculated channel impulse response (S400). That is, the coupling detector 600 is configured for the user data signal and the transport format combination indicator (TFCI), the power control bit (TPC, Transmit Power Control), and the SS (Synchronization Shift) based on the channel impulse response. Perform binding detection.

Then, the power of the transmission signal is controlled according to the magnitude of the impulse response calculated through the 'step S200' and the power control bit (S500). That is, when the calculated magnitude of the impulse response is larger than the predetermined value, the power controller 700 maintains the conventional power control scheme that adjusts the transmission power according to the power control bit. In addition, when the calculated magnitude of the impulse response is smaller than the predetermined value, the power controller 700 may transmit the transmission signal in the same manner as the transmission signal power increase of the power control bit even if the power control bit instructs to maintain the transmission signal power. Increase power In addition, when the calculated magnitude of the impulse response is smaller than the predetermined value, the power controller 700 maintains the state of the transmission signal power even if the power control bit indicates a decrease in the transmission signal power.

On the other hand, if the magnitude of the calculated impulse response is smaller than the predetermined value, the power controller 700 may determine that the power control bit is unreliable, and may be implemented to maintain the transmission power regardless of the power control bit.

Through the above-described configuration, the power control method in TD-SCDMA and the apparatus applied thereto according to the present invention transmit the power control by verifying the reliability of the transmission power control bit using the channel estimation information in decoding the transmission power control bit. Can improve reception performance.

In addition, by using the estimated information of the recent reception channel in the transmission power control operation, it is possible to effectively cope with a radio channel with a large change.

Although the present invention has been described in detail with reference to the preferred embodiments, the present invention is not limited to the above-described embodiments, and the present invention belongs to the present invention without departing from the gist of the present invention as claimed in the following claims. Anyone skilled in the art will have the technical idea of the present invention to the extent that various modifications or changes are possible.

Claims (18)

In the power control method in a complex time division-code division multiple access (TD-SCDMA, Time Division-Synchronous Code Division Multiple Access) system, a) separating the midamble signal from the radio signal received through the antenna; b) calculating a channel impulse response through channel estimation based on the separated midamble signal; c) extracting a user data signal and a transmit power control (TPC) based on the calculated channel impulse response; And and d) controlling power of a transmission signal according to the magnitude of the impulse response calculated through step 'b)' and the power control bit. According to claim 1, wherein the step a), a-1) demodulating and converting a radio signal received through the antenna into a baseband; And a-2) separating the midamble signal from the radio signal changed into the base band. The method of claim 1, wherein b), And calculating the channel impulse response through ML (Maximum Likelihood) estimation. The method of claim 1, wherein the d) step, When the magnitude of the calculated impulse response is larger than a predetermined value, the power of the transmission signal is increased, maintained, and decreased in response to an increase, hold, and decrease control operation of the transmission signal power according to the power control bit. Power control method in a TD-SCDMA system, characterized in that. The method of claim 1, wherein the d) step, TD-SCDMA, when the magnitude of the calculated impulse response is smaller than a predetermined value, increases the power of the transmission signal in response to the increase or maintenance control operation of the transmission signal power according to the power control bit. Power control method in the system. The method of claim 5, wherein the d) step, If the calculated magnitude of the impulse response is smaller than a predetermined value, the TD-SCDMA system maintains the power of the transmission signal in response to a control operation for reducing the power of the fraudulent transmission signal according to the power control bit. Power control method in The method of claim 1, wherein the d) step, And when the calculated magnitude of the impulse response is smaller than a predetermined value, power of a transmission signal is maintained regardless of the power control bit. In a TD-SCDMA system, The magnitude of the channel impulse response calculated through channel estimation for acquiring user data from the midamble signal included in the radio signal is compared with a predetermined setting value, and based on the comparison result and the power control bits extracted from the channel impulse response. A power control device in a TD-SCDMA system, characterized in that for controlling the power of a transmission signal. The method of claim 8, When the magnitude of the calculated impulse response is larger than the predetermined value, the power of the transmission signal is increased, maintained, and decreased in response to an increase, hold, and decrease control operation of the transmission signal power according to the power control bit. And a power control device in a TD-SCDMA system. The method of claim 8, When the calculated magnitude of the impulse response is smaller than the predetermined value, the power of the transmission signal is increased in response to the increase or maintenance control operation of the transmission signal power according to the power control bit. Power control device in SCDMA system. The method of claim 10, If the calculated magnitude of the impulse response is smaller than a predetermined value, the TD-SCDMA system maintains the power of the transmission signal in response to a control operation for reducing the power of the fraudulent transmission signal according to the power control bit. Power control device in The method of claim 8, And when the magnitude of the calculated impulse response is smaller than the predetermined set value, the power control apparatus of the TD-SCDMA system, wherein the power of the transmission signal is maintained regardless of the power control bit. A demodulator for demodulating the radio signal received through the antenna and converting the radio signal into a baseband signal; A midamble signal detector for separating a midamble signal from the baseband radio signal output from the demodulator; A channel estimator receiving the separated midamble signal and performing channel estimation to calculate a channel impulse response; A combined detector for receiving the calculated channel impulse response and extracting user data and power control bits; And And a power controller for controlling the power of the transmission signal based on the calculated magnitude of the channel impulse response and the extracted power control bits. The method of claim 13, wherein the channel estimator, Power control device in a TD-SCDMA system, characterized in that for calculating the channel impulse response through the ML (Maximum Likelihood) estimation. The method of claim 13, wherein the power controller, When the magnitude of the calculated impulse response is larger than a predetermined value, the power of the transmission signal is increased, maintained, and decreased in response to an increase, hold, and decrease control operation of the transmission signal power according to the power control bit. Power control device in the TD-SCDMA system, characterized in that. The method of claim 13, wherein the power controller, TD-SCDMA, when the magnitude of the calculated impulse response is smaller than a predetermined set value, increases the power of the transmission signal in response to the increase or maintenance control operation of the transmission signal power according to the power control bit. Power control device in the system. The method of claim 16, wherein the power controller, If the calculated magnitude of the impulse response is smaller than a predetermined value, the TD-SCDMA system maintains the power of the transmission signal in response to a control operation for reducing the power of the fraudulent transmission signal according to the power control bit. Power control device in The method of claim 13, wherein the power controller, And when the magnitude of the calculated impulse response is smaller than a predetermined value, power of the transmission signal is maintained regardless of the power control bit.

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