KR100729663B1 - CDM-type Receiver and Satellite DMB Terminal Having the Same - Google Patents

Abstract

The present invention relates to a receiver for automatically controlling interference cancellation according to reception performance to efficiently remove interference signals due to multipath, as well as minimizing power consumption.

The present invention provides an interference canceller for classifying code division multiplex signals received from a transmitter by multiple paths to remove interference signals from different paths for each path, and delaying the received code division multiplex signals by a predetermined delay time. A delay buffer, a switch for selecting any one of the interference canceller and the delay buffer, a finger configured for each path and demodulating the output signal of the switch using a despreading code, and combining data demodulated by the finger A code division multiplex receiver comprising a combiner, a performance analyzer for analyzing the performance of the combiner output, and an interference cancellation controller for activating or deactivating the interference canceller according to a performance analysis result of the performance analyzer.

The present invention improves performance by eliminating interference signals due to multipath when there is a performance problem due to signals received through a plurality of paths in a code division multiplexing receiver, and when there is no problem in performance. By eliminating the interference elimination function, power consumption can be increased in portable terminals by reducing power consumption.

Code Division Multiple, Receiver, Satellite DMB

Description

CDM-type Receiver and Satellite DMB Terminal Having the Same}             

1 is a block diagram of a typical rake receiver for data reception in a code division multiplexing scheme;

2 is a block diagram of a first interference cancellation receiver for removing interference signals due to multipaths in a code division multiplexing scheme;

3 is a block diagram of a second interference cancellation receiver for removing interference signals due to multipath in a code division multiplexing scheme;

4 is a block diagram of a receiver according to the first embodiment of the present invention; And

5 is a block diagram of a receiver according to a second embodiment of the present invention.

The present invention relates to a code division multiplexing receiver. More particularly, the interference cancellation function is automatically controlled according to the reception performance to efficiently remove the interference signal due to the multipath and to minimize the power consumption. It is about.

As is well known, in code division multiplexing, a plurality of channel data are spread by different spreading codes and then overlapped with the same frequency. The transmitted signal arrives through a plurality of paths until it reaches the receiver. Therefore, the receiver recognizes the multipath signals arriving at different times. A rake receiver is widely used as a code division multiplex receiver. The rake receiver classifies these multipath signals using spreading codes and demodulates the signals by finally combining the correlator outputs for all paths.

1 shows the configuration of such a general rake receiver. As shown in FIG. 1, the weak signal received through the antenna 11 is amplified by the reception amplifier 12 and then down-converted to the baseband in the down converter 13. The downconverted signal is demodulated by a despread code at a finger 14 configured for each path in a multipath environment. The demodulated finger outputs for each path are combined at the combiner 15, and the output of the combiner 15 is deinterleaved at the deinterleaver 16 and then error-restored at the error correction decoder 17 to output the final demodulation result. .

Since the signals from all the paths are together at the input of the finger 14 configured for each path, the output of the finger 14 is not only a result of the despreading demodulation for the corresponding path signal, but also an interference signal caused from a path outside the corresponding path. Include the result of despreading demodulation for. Interfering signals resulting from these other paths are a major cause of poor reception demodulation performance. Therefore, in order to increase the demodulation performance, the receiver of the code division multiplex transmission method should remove the interference signal from the multipath.

2 and 3 are block diagrams of a receiver for removing such interference signals.

As shown in FIG. 2, the signals passing through the antenna 21, the receiving amplifier 22, and the downconverter 23 are classified by the multipath in the interference canceller 24, and thus all the signals from the different paths of the respective paths. After the interference signals are removed, they are outputted to the finger 25 of the corresponding path. Therefore, the finger input of the corresponding path has no interference signal from the other path, and the finger output has only the result of the despreading demodulation for the corresponding path. The combiner 26 combines the finger outputs without such interference signal, thereby improving performance compared to the configuration of FIG.

3 differs in that the interference signal is removed from the output of the finger 34, unlike the interference signal is removed from the baseband signal which is the output of the down-converter 23 in FIG. Since the signals input to all the fingers 34 through the antenna 31, the receiving amplifier 32, and the down converter 33 include signals for all paths, the output of the fingers 34 is similar to that of FIG. In addition to the despreading demodulation result for the path signal, the despreading demodulation result for the interference signal generated from signals of other paths is included. The despreading demodulation result of the interference signal is removed by the interference canceler 35 among the outputs of the finger 34. Since the combiner 36 combines only the despreading demodulation results for the corresponding path, the same performance improvement as in the configuration of FIG. 2 is achieved.

However, the interference cancellation demodulation method consumes a lot of power because it is very complicated and requires high-speed signal processing compared to the rake receiver. Therefore, there is a problem that it is difficult to use the interference cancellation technology in a portable terminal using a battery. In particular, in the case of satellite DMB (Digital Multimedia Broadcasting) user terminal or satellite DMB dedicated user terminal, which are recently released, due to many power consumption problems, even though performance improvement is needed through the use of interference cancellation technology This situation is not adopted.

Propagation characteristics in mobile and wireless environments are constantly changing according to time and place, and the reception performance is constantly changing accordingly. At this time, even in most places and times, even if the interference canceller is not used, there is no problem in reception performance. In addition, if the performance of the receiver is above a certain threshold, there is no big difference in service, so only the threshold needs to be maintained.

In view of the above, the present invention integrates a rake receiver and an interference controller to operate an interference control function in an environment where high performance is required, and operates a rake receiver only in an area where high performance is not required, thereby enabling low power implementation. The purpose is to provide a method receiver.

The first invention is an interference canceller for classifying code division multiplex signals received from a transmitter into multiple paths and removing interference signals from different paths for each path, and receiving the received code division multiplex signals by a predetermined delay time. A delay buffer for delaying, a switch for selecting one of the interference canceller and the delay buffer, a finger configured for each path and demodulating the output signal of the switch using a despreading code, and data demodulated by the finger A code division multiplexing receiver comprising a combiner for coupling, a performance analyzer for analyzing the performance of the output of the combiner, and an interference cancellation controller for activating or deactivating the interference canceller according to a performance analysis result of the performance analyzer.

The second invention is configured for each path in a multipath environment and is a finger that demodulates using a despread code for a code division multiplex signal received from a transmitter, and an interference signal generated from signals of different paths for the output of each of the fingers. An interference canceller for removing despread demodulation data for a delay buffer for delaying the output of each finger by a predetermined delay time, a switch for selecting one of the interference canceller and the delay buffer, and output data of each switch A code division multiplexing receiver comprising a combiner for coupling, a performance analyzer for analyzing the performance of the output of the combiner, and an interference cancellation controller for activating or deactivating the interference canceller according to a performance analysis result of the performance analyzer.

The code division multiplex receiver is particularly suitable for a user terminal for satellite DMB (Digital Multimedia Broadcasting) service.

The above objects and features will become more apparent from the following detailed description taken in conjunction with the accompanying drawings, whereby those skilled in the art to which the present invention pertains may easily implement the technical idea of the present invention. . In addition, in describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

4 is a block diagram of a code division multiple access receiver according to a first embodiment of the present invention.

The code division multiplex receiver includes an antenna 401, a reception amplifier 402, a down converter 403, an interference canceller 404, a delay buffer 405, a switch 406, a finger 407, a combiner 408, The deinterleaver 409, the error correction decoder 410, the performance analyzer 411, and the interference cancellation controller 412 are included.

The reception amplifier 402 amplifies the code division multiplexing signal transmitted from the transmitter to the user terminal through the antenna 401 of the user terminal. The down converter 403 down converts the output signal of the reception amplifier 402 to the base band.

The interference canceller 404 classifies the downconverted signal by the downconverter 403 for each of the multiple paths and removes all the interference signals from the different paths for each path. As the configuration of the interference canceller 404, a linear interference cancellation method and a nonlinear interference cancellation method may be used.

In the linear interference cancellation method, a linear signal processing is performed with an adaptive filter on a reception signal itself including a signal of a multipath, thereby removing the interference between the multipaths and performing the same effect as the multipath signal combining. . At this time, the filter coefficient is adaptively changed to perform the optimal signal processing according to the characteristics of the mobile and wireless environment.

The nonlinear interference cancellation method is a method of analyzing signals of each path by multiple paths, estimating and removing interference signals from other paths included in each path signal, and then combining signals of each path from which the interference signal is removed. More specific interference cancellation scheme is well known to those skilled in the art, and thus a detailed description thereof will be omitted.

The output terminal of the down converter 403 is connected in parallel to the interference canceller 404 and the delay buffer 405. The delay buffer 405 has a delay time corresponding to the time it takes for a signal to be input to the interference canceller 404 to be output after the interference is removed. This is to maintain data synchronization at the time of change and to prevent data loss when changing the use of the interference canceller 404.

The switch 406 selects one of the interference canceller 404 and the delay buffer 405 according to the control signal of the interference cancellation controller 412 and transfers the corresponding output signal to the finger 407.

The finger 407 is configured for each path in a multipath environment and uses a despreading code for a signal that has been canceled through the interference canceller 404 or a signal that has not been canceled via the delay buffer 405. Demodulate

The combiner 408 combines a plurality of demodulated finger output data for each path. The de-interleaver 409 rearranges the deinterleaving, ie, the order of the output data of the combiner 408 in the original order before being interleaved. The error correction decoder 410 error corrects and restores the deinterleaved data and outputs the finally demodulated received data.

The performance analyzer 411 analyzes the performance of the output of the combiner 408 and sends the performance analysis result to the interference cancellation controller 412. The interference cancellation controller 412 outputs a control signal so that the interference canceller 404 does not perform interference cancellation based on the analysis result of the performance analyzer 411. A control signal is output to select 405. On the other hand, the interference cancellation controller 412 outputs a control signal for the interference canceller 404 to perform interference cancellation if the performance is less than or equal to the result of the analysis of the performance analyzer 411, and the switch 406 is the interference canceller 404. Output a control signal to select). The interference canceller 404 is activated according to the control signal of the interference cancellation controller 412 to perform the interference cancellation function or to be inactive to not perform the interference cancellation function.

The performance analysis is possible in a variety of ways. In particular, the code division multiplexing system periodically transmits a signal of a predetermined pattern (e.g., a pilot signal) promised in advance between transmission and reception, so that an error rate and Performance can be analyzed by estimating the signal-to-noise ratio.

Referring to the operation of the first embodiment according to the above configuration is as follows.

The performance analyzer 411 analyzes the performance of the output of the combiner 408, and as a result, the interference canceller 404 does not need to perform the interference cancellation function when the performance is good above the threshold. At this time, if the interference canceller 404 is performing the interference canceling function, the interference canceller 404 is deactivated by the control signal of the interference canceling controller 412, and at the same time, the switch 406 turns the delay buffer 405 on. Choose. Since the delay buffer 405 has the same delay as the delay during the operation of the interference canceller 404, instantaneous data loss is prevented even during a switch change and the receiver can be continuously operated. However, if the interference canceller 404 was not performing the interference cancellation function, then the interference canceller 404 would remain in an inactive state. Thus, the receiver according to the present invention operates as a general rake receiver without interference cancellation.

On the other hand, when the performance analyzer 411 analyzes the performance of the output of the combiner 408, the interference canceller 404 needs to perform the interference cancellation function when the performance is lower than the threshold. At this time, if the interference canceller 404 is performing the interference canceling function, the interference canceller 404 continues to perform the interference canceling function in an activated state. However, if the interference canceller 404 is not performing the interference canceling function, the interference canceller 404 is first activated by the control signal of the interference cancellation controller 412, and the delay time set by the delay buffer 405 is increased. In time, when the result of the interference cancellation function is valid, the switch 406 selects the interference canceller 404. Thus, continuous operation of the receiver is possible without instantaneous data loss. Thus, the receiver according to the present invention operates as an interference cancellation receiver.

This is summarized in Table 1 below.

condition action Over Threshold & Interference Rejection Switch Delay Buffer Selection Switched with Interference Canceller Disabled Over Threshold & No Interference Removal No interference removal Below threshold & performing interference cancellation Continue to remove interference Below threshold & no interference cancellation Toggle switch selector after delay time of delay buffer after activator

The above-described delay buffer 405, switch 406, performance analyzer 411 and interference cancellation controller 412 may be implemented to operate at a simple and low speed. Thus, very little power can be consumed.

5 is a block diagram of a code division multiple access receiver according to a second embodiment of the present invention. Compared to the first embodiment, the second embodiment has the performance analyzer 511 and the interference cancellation controller except that the positions of the interference canceller 506, the delay buffer 505, and the switch 507 are located behind the finger 504. The configuration of 512 is the same as the performance analyzer 411 and the interference cancellation controller 412, respectively.

The code division multiplex receiver includes an antenna 501, a reception amplifier 502, a down converter 503, an interference canceller 504, a delay buffer 505, a switch 506, a finger 507, a combiner 508, The deinterleaver 509, the error correction decoder 510, the performance analyzer 511, and the interference cancellation controller 512 are provided.

The reception amplifier 502 amplifies the code division multiplexing signal transmitted from the transmitter to the user terminal through the antenna 501 of the user terminal. The down converter 503 down-converts the output signal of the reception amplifier 502 to the base band.

The finger 507 is configured for each path in a multipath environment, and demodulates the downlinked signal to a decorrelator using a despreading code. The output of the finger 507 includes despread demodulation data for the corresponding path signal and despread demodulation data for the interference signal generated from signals of other paths.

The output end of each of the fingers 507 is connected in parallel to the interference canceller 504 and the delay buffer 505. The interference canceller 504 removes only the despread demodulation data for the interference signal at the output of each of the fingers 507. As the configuration of the interference canceller 504, a nonlinear interference cancellation scheme may be used. Since the specific interference cancellation method is well known to those skilled in the art, a detailed description thereof will be omitted.

The delay buffer 505 has a delay time corresponding to the time taken for a signal to be input to the interference canceller 504 and then output after the interference is canceled. This is to maintain data synchronization at the time of change and to prevent data loss when changing the use of the interference canceller 504.

The switch 506 selects one of the interference canceller 504 and the delay buffer 505 according to the control signal of the interference cancellation controller 512 and transfers the corresponding output signal to the combiner 508.

Combiner 508 combines the output data of switch 506 along each path. The de-interleaver 509 rearranges the deinterleaving, ie, the order of the output data of the combiner 508 in the original order before being interleaved. The error correction decoder 510 outputs the finally demodulated received data by performing error correction restoration on the deinterleaved data.

The performance analyzer 511 analyzes the performance of the output of the combiner 508 and sends the performance analysis result to the interference cancellation controller 512. The interference cancellation controller 512 outputs a control signal so that the interference canceller 504 does not perform interference cancellation based on the analysis result of the performance analyzer 511, and the switch 506 outputs a delay buffer ( A control signal is output to select 505). On the other hand, the interference cancellation controller 512 outputs a control signal for the interference canceller 504 to perform interference cancellation if the performance is less than or equal to a result of the analysis of the performance analyzer 511, and the switch 506 is an interference canceller 504. Output a control signal to select). The interference canceller 504 is activated according to the control signal of the interference cancellation controller 512 to perform the interference cancellation function or to deactivate the interference cancellation function.

Since the performance analysis method is the same as in the first embodiment, a detailed description thereof will be omitted. In addition, since the second embodiment also operates as summarized in Table 1, and operates in the same manner as in the first embodiment, a detailed description thereof will be omitted. The above-described delay buffer 505, switch 506, performance analyzer 511 and interference cancellation controller 512 may be implemented to operate at a simple and low speed. Thus, very little power can be consumed.

As described above, although the present invention has been described by way of limited embodiments and drawings, the present invention is not limited thereto and is intended by those skilled in the art to which the present invention pertains. Of course, various modifications and variations are possible within the scope of equivalents of the claims to be described.

The present invention improves performance by eliminating interference signals due to multipath when there is a performance problem due to signals received through a plurality of paths in a code division multiplexing receiver, and when there is no problem in performance. By eliminating the interference elimination function, power consumption can be increased in portable terminals by reducing power consumption.

Claims (9)

An interference canceller configured to classify the code division multiplex signal received from the transmitter into multiple paths and to remove interference signals from different paths for each path; A delay buffer for delaying the received code division multiplex signal by a predetermined delay time; A switch for selecting any one of the interference canceller and the delay buffer; A finger configured for each path and demodulating the output signal of the switch using a despread code; A combiner for combining the demodulated data by the finger; A performance analyzer for analyzing performance on the output of the combiner; And An interference cancellation controller for activating or deactivating the interference canceller according to a performance analysis result of the performance analyzer Code division multiplex receiver comprising a. A finger configured for each path in a multipath environment and demodulating a code division multiplex signal received from a transmitter using a despread code; An interference canceller for removing despread demodulation data for interference signals generated from signals of different paths for the output of each of the fingers; A delay buffer for delaying the output of each finger by a predetermined delay time; A switch for selecting any one of the interference canceller and the delay buffer; A combiner for coupling the output data of each of the switches; A performance analyzer for analyzing performance on the output of the combiner; And An interference cancellation controller for activating or deactivating the interference canceller according to a performance analysis result of the performance analyzer Code division multiplex receiver comprising a. The method according to claim 1 or 2, The interference cancellation controller Outputting a control signal for deactivating the interference canceller and outputting a control signal for the switch to select the delay buffer when the performance is greater than or equal to a threshold value based on an analysis result of the performance analyzer; Outputting a control signal for activating the interference canceller and outputting a control signal for the switch to select the interference canceller if performance is below a threshold. Code Division Multiple Access Receiver. The method of claim 3, If the performance is above the threshold, if the interference canceller was in the middle of performing the interference cancellation function, the interference canceller is deactivated by the control signal of the interference cancellation controller, and at the same time, the switch selects the delay buffer. Code Division Multiple Access Receiver. The method of claim 3, When the performance is below a threshold, if the interference canceller has not performed the interference canceling function, the interference canceller is first activated by a control signal of the interference cancellation controller, and after the predetermined delay time has elapsed, the switch stops the interference. To choose eliminator Code Division Multiple Access Receiver. The method according to claim 1 or 2, The predetermined delay time Corresponds to the time it takes for a signal to be input to the interference canceller and output after the interference cancellation is performed. Code Division Multiple Access Receiver. The method according to claim 1 or 2, The performance analyzer Performance analysis is performed by estimating the error rate and the signal-to-noise ratio by comparing the output data of the combiner and the pilot signal. Code Division Multiple Access Receiver. In the user terminal for satellite DMB (Digital Multimedia Broadcasting) service, The user terminal, A receiver for receiving and demodulating a code division multiplex signal from a satellite; A data processor which processes an image signal of the output signal of the receiver; And A display unit displaying the image signal processed signal Including; The receiver, An interference canceller for classifying the code division multiplexed signal into multiple paths to remove interference signals from different paths for each path; A delay buffer for delaying the received code division multiplex signal by a predetermined delay time; A switch for selecting any one of the interference canceller and the delay buffer; A finger configured for each path and demodulating the output signal of the switch using a despread code; A combiner for combining the demodulated data by the finger; A performance analyzer for analyzing performance on the output of the combiner; And An interference cancellation controller for activating or deactivating the interference canceller according to a performance analysis result of the performance analyzer User terminal for satellite DMB service comprising a. In the user terminal for satellite DMB (Digital Multimedia Broadcasting) service, The user terminal, A receiver for receiving and demodulating a code division multiplex signal from a satellite; A data processor which processes an image signal of the output signal of the receiver; And A display unit displaying the image signal processed signal Including; The receiver, A finger configured for each path in a multipath environment and demodulating the code division multiplex signal using a despread code; An interference canceller for removing despread demodulation data for interference signals generated from signals of different paths for the output of each of the fingers; A delay buffer for delaying the output of each finger by a predetermined delay time; A switch for selecting any one of the interference canceller and the delay buffer; A combiner for coupling the output data of each of the switches; A performance analyzer for analyzing performance on the output of the combiner; And An interference cancellation controller for activating or deactivating the interference canceller according to a performance analysis result of the performance analyzer User terminal for satellite DMB service comprising a.

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