KR20080011823A - Method and apparatus for adaptive antenna controlling in mobile telecommunication system - Google Patents

Abstract

A method and an apparatus for adaptively controlling multiple-output antenna paths in a mobile telecommunication system are provided to minimize power consumption of an entire terminal by controlling power applied to a specific receiver. A method for adaptively controlling multiple-output antenna paths in a mobile telecommunication system includes the steps of: performing diversity combining of signals received through multiple-output antennas; estimating dispersion by using an SNR(Signal to Noise Ratio) and a CINR(Carrier to Interference and Noise Ratio) of the diversity-combined signal(504); checking whether the estimated dispersion is within a predetermined threshold to satisfy a maximum diversity gain(506); and changing the antenna path according to a result of checking.

Description

Receiving apparatus and method for adaptively controlling multiple receive antenna paths in a mobile communication system {METHOD AND APPARATUS FOR ADAPTIVE ANTENNA CONTROLLING IN MOBILE TELECOMMUNICATION SYSTEM}

1 is a view showing an example of a receiving device having multiple receive antennas according to the prior art.

2 is a diagram illustrating an example of a reception device for adaptively controlling multiple reception antennas in accordance with the present invention.

3 is an example illustrating a structure of a controller for adaptively controlling multiple reception antennas according to the present invention.

4 is a diagram illustrating a threshold range as an example of controlling multiple reception antennas according to the present invention.

5 is a flowchart illustrating a control process of a controller for adaptively controlling multiple receive antennas according to the present invention.

The present invention relates to a mobile communication system, and more particularly, to a method and a receiving apparatus for adaptively controlling multiple receive antenna paths.

The quality of the radio link between the terminal and the base station is constantly changed by time selective fading due to Doppler spread occurring as the terminal moves. In addition, even when the terminal is stopped, the situation of the radio link can be changed at any time due to the movement of the surrounding reflector or random interference of other user terminals.

Accordingly, when a receiver having a single antenna structure is used, the mobile station may have a poor reception performance due to a change in radio link quality. The deterioration of the reception performance of the terminal may lead to service interruption or synchronization acquisition failure.

In a mobile communication system, a terminal always wants to receive service from a base station that provides an optimal radio link. Since the above-mentioned variation of the radio link quality is several tens of dB, the optimal radio link selection under such an environment may cause frequent handover, that is, ping-pong phenomenon.

Therefore, when the variation of the radio link quality is large, the mobile communication system configures multiple antenna receivers so as to obtain a radio link by combining radio link quality from the base station to each antenna receiver.

In other words, in a dynamic wireless environment such as a multi-path and a multi-user terminal, an interference cancellation technique and a multiple receive antenna technique may be used to increase the reception performance of the terminal. Such an interference cancellation technique and a multiple reception antenna technique are already known technologies, but in the case of an actual commercially available terminal, they are not spread due to an increase in price and power consumption of multiple reception antenna hardware.

However, for the smooth service of the high-speed portable Internet, the current mobile communication system is emphasizing the necessity of the above-described interference cancellation technique in the form of a terminal, and also requires the use of the multiple receive antenna technique in the portable Internet standard. .

1 is a diagram illustrating an example of a reception device, ie, a terminal, to which a multiple reception antenna scheme is applied according to the prior art. 1 shows a terminal having N receivers, where N is assumed to be 3. FIG. In FIG. 1, the first receiver includes a reception antenna (A # 1) 100, an RF unit 102, an analog / digital (A / D) converter 104, a filter 106, and an FFT unit 108. do. The second receiver includes an A # 2 110, an RF unit 112, an A / D converter 114, a filter 116, and an FFT unit 118. The third receiver includes an A # N 120, an RF unit 122, an A / D converter 124, a filter 126, and an FFT unit 128. The signals received through the receivers are decoded through a diversity combiner 150, a log likelihood ratio 160, and a channel decoder 170.

In more detail with reference to Figure 1, the signal transmitted from the transmitting side is received through the A # 1 (100). The signal received through the A # 1 100 is transferred to the A / D converter 104 via the RF unit 102. The A / D converter 104 converts the transmitted analog signal into a digital signal and then transmits the converted analog signal to the filter 106. The filter 106 outputs only the signal of a specific band including the OFDM transmission symbol from the signal transmitted from the A / D converter 104 to the FFT 108. The FFT unit 108 converts the samples of the 0FDM signal into a frequency domain and outputs subcarrier signals. This operation is performed identically at each of the second receiver and the third receiver.

The combiner 150 combines the signals transmitted from the first receiver, the second receiver, and the third receiver, and then transfers the signals to the LLR 160. That is, the combiner 150 is provided with the plurality of receiving antennas (A # 1) (100) to increase the transmission efficiency of the received signal. The diversity effect is increased by weighting different weights on the signals transmitted through the A # 2 110 and the A # 3 130, and performing combining by applying the different weights.

LLR 160 estimates the modulation symbol sequence to the original information values. That is, the LLR values corresponding to the respective information bits are estimated according to the code rate of the transmitter or the encoding related parameter, and then output to the channel decoder 170.

The channel decoder 170 decodes the LLR values according to a coding scheme and a coding rate.

However, as described above, the terminal of the dual receive antenna structure according to the related art has an RF circuit and a baseband demodulation circuit added with the multiple receivers to increase the price of hardware, and the multiple receivers There is still a problem that the power consumption of the terminal due to the increase.

In addition, due to the addition of a demodulation circuit according to the multi-receiver operation, there is a problem in that a form factor for determining the appearance of the terminal increases. The external expansion of such a terminal has a problem that cannot satisfy the needs of modern terminal consumers having a strong tendency toward a trend, such as a new design, miniaturization, and slimness.

Therefore, in order to operate a commercial terminal sensitive to power consumption, a definition of how to operate multiple receive antennas as necessary and how to operate multiple antennas when operating multiple receive antennas is urgently needed. That is, while a terminal having a multiple reception antenna structure guarantees the reception performance to the maximum, there is a need for a method for reducing power consumption of the terminal to the maximum.

Accordingly, the present invention devised to solve the problems of the prior art operating as described above provides an apparatus and method for adaptively controlling the path of multiple receive antennas in a mobile communication system.

The present invention also provides a receiving apparatus and method for adaptively controlling the power supply of multiple receiving antennas in a mobile communication system.

The present invention provides a method for adaptively controlling the paths of the antennas in an apparatus having multiple receive antennas, the method comprising: diversity combining signals received through the multiple receive antennas, and diversity diversity. Estimating a variance using a signal-to-noise ratio of the estimated signal and an interference signal (CINR), checking whether the estimated variance is within a threshold range set to satisfy a maximum diversity gain, and And changing the antenna path in response to the verification result.

The present invention relates to a reception apparatus including multiple reception antennas for adaptively controlling a path of multiple reception antennas, comprising: a combiner for diversity combining signals received through the multiple reception antennas, and the combiner; A control unit for estimating a variance of the combined signal output from the control unit and checking whether the estimated variance is within a threshold range set to satisfy a maximum diversity gain, and applying a control command to change the multiple receive antenna paths; And a switch calculator configured to change a path of the multiple reception antennas by turning on / off a power supply according to a control command of the controller.

The present invention is a control unit for adaptively controlling the path of the multiple receive antennas, the dispersion calculation unit for estimating the variance by using the ratio of the signal-to-noise and interference signal (CINR) of the diversity combined signal, And a power / switch control unit having a table including an upper limit threshold for additionally setting an antenna path and a lower limit threshold for deleting an antenna path for the estimated variance to satisfy the maximum diversity gain. It is done.

Hereinafter, the operating principle of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a known function or configuration may unnecessarily flow the gist of the present invention, the detailed description thereof will be omitted. Terms to be described later are terms defined in consideration of functions in the present invention, and may be changed according to intentions or customs of users or operators. Therefore, the definition should be made based on the contents throughout the specification.

The present invention proposes a terminal having multiple reception antennas for a next generation wireless communication service. In particular, the present invention provides a method and a reception apparatus for adaptively adjusting the number of multiple reception antennas according to the quality of a radio link.

The present invention discloses a reception device having multiple reception antennas. In the case of using a receiver having a multi-antenna structure, the variation of the radio link quality change due to various antenna path gains is reduced and the effect of selectively amplifying only signal components. Can be obtained. In addition, when communicating with a base station using multiple transmit antennas, high data transmission is possible due to an increase in the capacity of a radio link.

Therefore, the present invention proposes an adaptive antenna reception algorithm in order to reduce the high power consumption that occurs when using the proposed multi-antenna receiver to overcome the disadvantages of a single antenna receiver. In other words, we propose a control method that activates multiple receive antenna paths only when necessary.

 2 is a diagram illustrating an example of a reception device having a plurality of reception antennas adaptively according to the present invention. 2 shows a receiving apparatus having N receivers, where N is described with an example of 3. FIG.

In FIG. 2, the first receiver includes a reception antenna (A # 1) 200, an RF unit 202, an A / D converter 204, a filter 206, and an FFT unit 208. The second receiver includes an A # 2 210, an RF unit 212, an A / D converter 214, a filter 216, and an FFT unit 218. The third receiver includes an A # N 220, an RF unit 222, an A / D converter 224, a filter 226, and an FFT unit 228. In addition, the receiver includes a diversity combiner 250, an LLR 260, a channel decoder 270, and further includes a switch calculator 240 and a controller 230 for adaptation. By controlling the operation of the receiver.

Referring to FIG. 2, the first receiver may include the following blocks.

The RF unit 202 performs frequency down modulation on the radio signal received through the A # 1 200, that is, the frequency up-modulated from the transmitter. The A / D converter 204 converts the analog signal transmitted from the RF unit 202 into a digital signal, and then performs sampling and quantization. The filter 206 removes unwanted frequency components from the sampled or quantized digital signal and outputs a signal of a desired frequency band. The filter 206 may be used when over-sampling. The FFT unit 208 is a block that performs fast Fourier transform. The FFT unit 208 converts the signals including the OFDM transmission symbols in the time domain into signals in the frequency domain and outputs them as subcarrier signals.

The second receiver and the third receiver are composed of the same blocks as the first receiver and have a structure in parallel with the first receiver. The second receiver and the third receiver receive signals transmitted from the transmitter through A # 2 210 and A # N 220.

The diversity combiner 250 combines the received signals inputted through the A # 1 200, the A # 2 210, and the A # N 220 at an optimal ratio, and then combines the diversity. Find the benefit. At this time, the diversity gain is maximized by adjusting the weights of the A # 1 200, A # 2 210, and A # N 220. The result of the diversity combiner 250 is returned to the controller 230.

LLR 260 is a block that compares the exponential portions of a Gaussian distribution, and estimates the original information values of the combined signal, ie, the combined modulated OFDM symbols. The channel decoder 270 decodes the estimated LLR values according to a coding scheme or a coding rate.

In the present invention, if the controller (Adaptive Antenna Controller) 230 obtains the diversity gain from the diversity combiner 250, in other words, using the result value, it is confirmed that the overall diversity gain is reduced by a specific receiver. The switch operator 240 is controlled to enable / disable the operation of the receivers so as to adjust the diversity gain to the maximum. The control unit 230 is a block for giving a control command to the switch operation unit 230 in the form of a matrix whether the receiver is activated.

The switch calculator 240 is a block for switching the activation / deactivation of the receivers according to a control command of the controller 230. The switch matrix 240 is a passive block for turning on / off a switch per antenna path. The switch calculator 240 has a switch array structure.

Accordingly, the switch calculator 240 outputs the signals received from the receivers other than the receiver deactivated by the controller 230 to the diversity combiner 250. Accordingly, the diversity combiner 250 performs diversity combining on the signals received from the activated receivers to ensure radio quality and maximize diversity diversity.

As described above, the controller 230 deactivates a specific receiver which does not guarantee the antenna path, that is, the signal quality, of the switch calculator 240. The switch calculator 240 deactivates the specific antenna path by changing the antenna matrix in response to the control command of the controller 230. In addition, when the antenna path is not deactivated, it means that power applied to all blocks constituting the receiver corresponding to the antenna path is turned off.

In other words, according to the present invention, the control unit 230 applies a control command to the switching operation unit 240 to control a specific receiver that does not guarantee efficiency in the diversity gain in an inactive state, that is, the RF circuit and demodulation constituting the specific receiver. By not applying power to the circuits, it is possible to save the overall power consumption of a receiving device having multiple receive antennas.

3 is a diagram illustrating an example of a controller for adaptively controlling a plurality of receive antennas according to the present invention.

Referring to FIG. 3, the controller 300 adaptively controls antennas, that is, receivers, to activate / deactivate an operation. Although the control unit 300 is denoted by reference numeral 230 in FIG. 2, this refers to the same configuration.

The control unit 300 estimates the deviation of the normalized signal quality, which is a variable process, from the value of the calculated CINR and a CINR calculation unit 310 that calculates a CINR, which is a signal quality measure, from the received signal of the diversity combiner 250. The dispersion calculator 320 includes a power / switch controller 330 including a threshold table that defines how many antennas are appropriate based on the normalized signal quality deviation. here,

In particular, the power / switch control unit 330 deactivates one antenna path if the normalized signal quality deviation is less than a lower threshold for the number of antennas currently in use, and excludes the antenna path from the diversity combining process. 2 is a block for applying a control command to the switch operation unit 240 of FIG. 2. On the contrary, if the normalized signal quality deviation is greater than the upper limit threshold for the number of antennas currently in use, one antenna path is activated and the switch operation unit 240 is controlled to include the antenna path in the diversity combining process.

Here, the carrier to interference and noise ratio (CINR) represents a ratio between a signal including an OFDM transmission symbol and a signal received through noise and another antenna path. Estimating the CINR is not a subject matter of the present invention, and the invention for estimating the CINR is described in detail in 2004-37956 filed by the same applicant, and the description thereof will be omitted.

4 is a diagram illustrating an example of a power / switch controller for controlling the number of receiving antennas by applying a threshold range according to the present invention.

Referring to FIG. 4, when the variance value of the CINR of the combined signal received through the used antennas (eg, A # 1 to A # 3) is greater than the predetermined upper limit of the antenna, the CINR value may be determined. Since the mean of scattering is large, the present invention aims to stabilize the estimate of the CINR value by reducing the dispersion of the CINR value. Therefore, to reduce the dispersion of the CINR value, additional antenna paths must be secured to obtain diversity effects. Here, the scatter represents how scattered the data is from the mean, and the variance is defined as the mean of the square of the distance between the data value and the average.

In addition, when the dispersion value of the CINR is smaller than the predetermined lower limit value, it means that the distribution of the CINR value is very small. Therefore, even if the distribution of the CINR value is slightly increased, stable reception is possible. It is desirable to reduce.

Accordingly, the power / switch control unit includes a table as shown in FIG. 4 to change the switch matrix by applying a control command to the switch operation unit to add / delete the antenna path.

In the table of FIG. 4, the antenna upper limit threshold is defined as an antenna add threshold, and the antenna lower limit threshold is defined as an antenna drop threshold for excluding an antenna path. The above-mentioned thresholds are implementation and operational parameters at the receiving device, and optimization of this parameter can be achieved through data collection through field testing.

For example, in the case of using one antenna in FIG. 4, the upper limit threshold as a reference is set to a dispersion value of T11, and the lower limit threshold is set to 0 since the number of antennas used is one.

In addition, when two antennas are used, the upper limit threshold as a reference is set to the dispersion value of T21, and the lower limit threshold is set to the dispersion value of T22.

More specifically, when the number of antennas currently used is 1, only the antenna path is T11. At this time, it is checked whether the estimated variance value of the received signal is smaller than the predetermined variance value of T11, that is, the upper limit threshold value and the lower limit threshold value 0.

When the estimated variance value satisfies the threshold range, the receiving device which sets only the T11 as the antenna path can receive signals transmitted from the transmitter and exhibits an optimal diversity gain without changing the antenna path. Can be. On the other hand, if the estimated variance value is greater than the variance value of T11, it should be changed to add an antenna path to reduce the dispersion of the CINR value.

In addition, when the number of antennas used is 2, it is checked whether the variance value of the signal received and combined through the two antennas is within the variance value of the upper limit T21 and the variance value of the lower limit T22. At this time, if the variance of the combined signal is within the variance of the upper limit T21 and the variance of the lower limit T22, the current number of antennas is maintained. This means that the variance value of the combined signal of the signals received through the antennas T21 and T22 is guaranteed to the maximum diversity gain through two antenna paths T21 and T22.

On the other hand, if the variance value of the combined signal is greater than the variance value of the upper limit T21, the switching matrix is changed to add an antenna path, that is, to use one more antenna. On the other hand, if the variance value of the combined signal is smaller than the variance value of the lower limit T22, only the antenna that guarantees signal gain at the current antenna number, i.e., does not guarantee diversity gain Change the switching matrix to delete the antenna path.

Here, changing the switch matrix by the power / switch controller means turning on or off the power of the receiver corresponding to the corresponding antenna path.

5 is a signal flow diagram illustrating a control process of a controller for adaptively controlling a plurality of receive antennas according to the present invention. The control unit includes a block for calculating a CINR, a block for calculating a variance using the calculated CINR, and a control unit for controlling the antenna path through the calculated variance according to the present invention.

Referring to FIG. 5, in step 500, the CINR calculator of the controller estimates a CINR value from the combined received signal. The estimated CINR value is passed to the variance calculator.

The variance calculator estimates the CINR variance for the CINR. Thus, in step 502 an average is obtained for the signals received through each antenna path. Here, <Equation 1> for obtaining the average is as follows.

Where X1 represents the level of power or received signal received from antenna path 1, and N represents the total number of antenna paths.

That is, in operation 502, the dispersion calculator estimates an average value by dividing the sum of powers (levels of received signals) of signals received through respective antenna paths by the total number of antenna paths.

In operation 504, the variance calculator estimates the variance as shown in Equation 2 below.

That is, in step 504, the variance calculator subtracts the square of the average value obtained in step 502 from the sum of the squares of the powers (signal levels) of the signals received through the respective antenna paths by the total number of antenna paths. Estimate the sample variance. Since the sample variance calculated in this way has a bias with respect to the actual variance, it is multiplied by N / (N-1) to obtain an estimated value of the parent variance from which the bias is removed.

In step 506, the power / switch control unit finds a row including the number of antennas currently used, that is, the number N of antenna paths. It is checked whether the estimated dispersion value is within a set threshold range, that is, an upper limit threshold value and a lower limit threshold range corresponding to the current antenna path.

If it is within the threshold range set in the step 506, that is, if the output value of the variance calculator is between the upper and lower threshold values indicated by the current row, the flow proceeds to step 508 to determine the current antenna path, i.e., the current number of antennas. Keep it. In step 530, the controller applies a control command to maintain the current antenna path to the switch calculator.

On the other hand, if the variance calculated in step 506 is not within the range, the flow proceeds to step 510 to check if the variance exceeds a set upper limit threshold. If the CINR output value of the variance calculator is greater than the upper threshold indicated by the current row, the process proceeds to step 512 and determines to add one more antenna path. In step 530, the controller applies a control command to newly set the antenna path to the switch calculator. Accordingly, the switch operation unit receiving the control command changes the switch matrix and newly sets the antenna path.

In addition, if the variance calculated in step 506 does not exist within the range, the flow proceeds to step 520 to check whether the variance is less than the set lower limit threshold. If the output value of the variance calculator is less than the lower limit threshold indicated by the current row, the process proceeds to step 522 and determines to reduce one antenna path. In step 530, the controller applies a control command to delete one antenna path from the current antenna path. Accordingly, the switch operation unit receiving the control command changes the switch matrix and newly sets the antenna path.

Therefore, the present invention reduces the variation in quality by using more receiving antennas in a wireless environment where the variation in received signal quality is large, while using a smaller number of receiving antennas in a wireless environment where the variation in received signal quality is less. It is possible to implement a terminal having optimized performance by reducing power consumption of the entire terminal by turning off power applied to a device, that is, a specific receiver. In addition, by controlling the received signal quality deviation of the terminal by the distribution can help to control the ping pong generation during handover (Hand-over).

In the present invention operating as described above in detail, the effects obtained by the representative of the disclosed invention will be briefly described as follows.

The present invention provides a stable receiving apparatus for minimizing quality variation of a received signal in response to a rapidly changing wireless channel in performing diversity combining of multiple receiving antennas. In addition, by adaptively controlling the antenna path in response to the received signal quality variation, it controls the power applied to a specific receiver to reduce the diversity combining, thereby minimizing the power consumption of the entire terminal. This has the advantage of increasing the waiting time for providing the actual service.

Claims (10)

A method for adaptively controlling the paths of antennas in an apparatus having multiple receive antennas, the method comprising: Diversity combining the signals received through the multiple receive antennas; Estimating variance using a ratio of signal-to-noise and interference signals (CINR) of the diversity combined signal; Checking whether the estimated variance is within a threshold range set to satisfy a maximum diversity gain; And changing the antenna path in response to the verification result. The method of claim 1, wherein estimating the variance comprises: An average value is obtained by using the sum of the signals received through the multiple reception antennas and the total number of antenna paths, and the square value of the signal received through each of the multiple reception antennas, the average value, and the multiple reception antennas. Adaptive multi-receive antenna control method characterized in that the process of estimating the variance using the number of paths. The method of claim 1, wherein the set threshold range, And an upper limit threshold for additionally setting an antenna path and a lower limit threshold for deleting an antenna path. The method of claim 3, wherein the changing of the antenna path in response to the checking result comprises: And if the estimated variance is within the set threshold range, maintaining the antenna path. The method of claim 3, wherein the changing of the antenna path in response to the checking result comprises: And if the estimated variance is greater than the set upper limit threshold, adding an antenna path to reduce the variance to satisfy the maximum diversity gain. The method of claim 3, wherein the changing of the antenna path in response to the checking result comprises: And if the estimated variance is less than the set lower limit threshold, deleting the antenna path to increase the variance to satisfy the maximum diversity gain. The method of claim 1, wherein changing the antenna path comprises: Adaptive multi-receive antenna path control method characterized in that the process of controlling the antenna path to enable / disable. A reception apparatus including multiple reception antennas for adaptively controlling a path of multiple reception antennas, A combiner for diversity combining the signals received through the multiple receive antennas; Estimating a variance of the combined signal output from the combiner and confirming that the estimated variance is within a threshold range set to satisfy the maximum diversity gain to apply a control command to change the multiple receive antenna path With my fisherman, And a switch calculator configured to change a path of the multiple reception antennas by turning on / off a power supply according to a control command of the controller. The method of claim 8, wherein the control unit, A variance calculator for estimating variance using a ratio of signal-to-noise and interference signals (CINR) of the diversity combined signal; And a power / switch control unit having a table including an upper limit threshold for additionally setting an antenna path and a lower limit threshold for deleting an antenna path for the estimated variance to satisfy the maximum diversity gain. Multiple reception antenna device. The method of claim 8, wherein the control unit, An average value is obtained by using the sum of the signals received through the multiple reception antennas and the total number of antenna paths, and the square value of the signal received through each of the multiple reception antennas, the average value, and the multiple reception antennas. And a variance is calculated using the number of paths.

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