KR20030058734A - Tx diversity detection apparatus and method for mobile communication system - Google Patents

Abstract

PURPOSE: An antenna diversity detecting apparatus and method of a mobile communication system is provided to re-detect an antenna diversity detected from primary and second detections, or verify or search an antenna diversity through a third-step cell searching. CONSTITUTION: Multiple correlation detectors(100-107) receive complex signals(I/Q) from an antenna and correlates it to a self-generated scramble code. A code and diversity detector(7) judges a code number and whether an antenna diversity has been used according to an energy value detected by the correlation detectors(100-107). A correlation operation is formed on a received complex signal. When the correlation operation is completed, an absolution value of a difference value between an energy of an antenna 1 and an energy of an antenna 2 is obtained. A diversity is detected according to whether the absolute value is greater than or smaller than a certain energy.

Description

Device and method for detecting antenna diversity in mobile communication system {TX DIVERSITY DETECTION APPARATUS AND METHOD FOR MOBILE COMMUNICATION SYSTEM}

The present invention relates to an apparatus and method for detecting antenna diversity in a mobile communication system, and in particular, to examine antenna diversity (Tx Diversity) detected in steps 1 and 2 of an asynchronous mobile communication system, or to search for cells in three steps. The present invention relates to an antenna diversity detection apparatus and method for performing antenna diversity verification and search through (code number detection).

In general, spatial diversity to overcome the effects of fading is a method of using two or more receiving antennas that are spaced sufficiently apart.

In order to achieve spatial diversity, the signals coming from different antennas must not be correlated with each other, so the distance between the antennas should be far enough apart. This is difficult to achieve when the receiver is small in hand and difficult to obtain an equally strong signal. In addition, there is a problem in the price and power of the terminal.

Therefore, the mobile communication system serves hundreds or thousands of terminals and is equipped with a base station, which is limited in sufficient space and complexity for a plurality of antennas in comparison with the terminals, thereby increasing the performance of the forward link diversity. Is using.

FIG. 1 is a diagram illustrating a configuration of a common pilot channel (CPICH) among downlink channels of an asynchronous mobile communication system.

In general, when antenna diversity (Tx Diversity) is used in the downlink, two patterns of antenna 1 and antenna 2 are transmitted, and only the pattern of antenna 1 is transmitted when antenna diversity is not used.

Looking at the pattern of the antenna 1, the same symbol data (A) is always repeated repeatedly. Looking at the pattern of the antenna 2, the symbol data (A, -A, -A, A) of a predetermined format is repeated.

Here, A is a constant value and one A is held for 1 Symbol, that is, 256 chips.

In terms of transmit power, the same power is used both with and without antenna diversity.

In other words, when diversity is used, the sum of the transmission powers of antenna 1 and antenna 2 is set to be the same as the transmission power of antenna 1 when diversity is not used.

In addition, when using antenna diversity (Tx Diversity), the terminal receives signals from two antennas at the same time.

Therefore, when despreading is not performed using the antenna diversity pattern, the energy value in symbol units is 0 or K4A ⁴ , and thus the average energy value is 2KA ⁴ (where K is the sum of the transmission power gains. to be.)

However, two-symbol coherent detection using antenna diversity results in the despread symbol becoming 4KA ² (value for two transmission symbols), and the energy per 256 chips (1 symbol) is 8KA ⁴ (Antenna1). Energy and Antenna2 Energy).

However, the relative noise power is also doubled, resulting in an effective energy of 4KA ⁴ per 256 chips (one symbol).

In the case of antenna diversity, the non-diversity detection method is equivalent to seeing 3dB loss in terms of received power, and consequently, causes a performance degradation factor.

To this end, the 3'rd Generation Partnership Project (3GPP) requires the use of an indicator indicating whether antenna diversity is present in the first and second synchronization channels.

However, detection errors may occur because the period of these synchronization channels is short and there is not enough way to correctly perform coherent detection.

Therefore, it is necessary to re-inspect the antenna diversity detection results obtained during the first and second phases of the primary synchronous channel detection and the second synchronous detection, and in some cases, the first and second Although antenna diversity detection is omitted in the discovery process and antenna diversity detection is possible in the third discovery process, there is no antenna diversity detection method in step 3 at present.

Here, the first step discovery process is a process for slot synchronization, the second process is a discovery process for frame synchronization and a base station code group, and the third process is a process for searching a PN code number of a current base station.

Accordingly, the present invention has been made to solve the above-described problems, and the code number, which is a three-stage search device, is used to reconsider antenna diversity (Tx Diversity) detected in the first and second search of the asynchronous mobile communication system. An object of the present invention is to provide an apparatus and method for detecting antenna diversity in a mobile communication system, which can be performed by a searcher or to perform antenna diversity verification and search by a three-stage search apparatus alone.

According to an aspect of the present invention, there is provided a code number search apparatus for an asynchronous mobile communication system, comprising: a plurality of correlation detectors for receiving a time diversity effect by receiving a complex signal (I / Q) received from an antenna; And a code and diversity detector for determining a code number and antenna diversity based on energy values detected through the plurality of correlation detectors.

In addition, the present invention for achieving the above object, in the code search and antenna diversity detection of the asynchronous mobile communication system, performing a correlation operation on the received complex signal; If the correlation operation is completed, the absolute value of the difference value of the energy of the antenna 1 (E _Antenna1) and energy (E _Antenna2) of the antenna _{2 (| E Antenna1 -E Antenna2 |} ) obtaining a and; It is characterized in that it comprises the step of detecting the diversity by whether the absolute value (| E _Antenna1 -E _Antenna2 |) is greater than or equal to a predetermined energy alpha1 or less than or equal to a predetermined energy alpha2.

1 is an exemplary view showing the configuration (Antenna diversity pattern) of the CPICH of the downlink channel of the asynchronous mobile communication system.

2 is a block diagram showing the configuration of a code number detection device as a third step of a cell search apparatus of a mobile communication terminal according to the present invention;

3 is a block diagram showing a detailed configuration of a correlation detector in FIG.

4 is a block diagram showing the detailed configuration of the non-coherent inverse diffuser in FIG.

FIG. 5 is a block diagram showing the detailed configuration of the coherent despreader in FIG.

6 is a flowchart illustrating a process for determining diversity in a code and diversity detector according to the present invention.

*** Explanation of symbols for the main parts of the drawing ***

100 to 107: correlation detector 1: multiplier

2: scramble code generator 3: non-coherent reverse diffuser

4 coherent reverse diffuser 5 first energy accumulator

6 second energy accumulator 7 code and diversity detector

The present invention relates to a code search apparatus and method using a three-step process capable of detecting antenna diversity (Tx Diversity) of the method for cell search, will be described in detail with reference to the accompanying drawings, preferred embodiments of the present invention.

2 is a block diagram showing the configuration of a cell search apparatus of a mobile communication terminal according to the present invention, and receives a complex signal (I / Q) received from an antenna (not shown) and correlates with a scramble code generated by itself. Correlation detectors 100-107; A code and diversity detector 7 determines a code number and antenna diversity based on the energy values detected by the correlation detectors 100 to 107.

In this case, the correlation detector may be physically configured to less than eight according to the implementation method.

3 is a block diagram showing the detailed configuration of the correlation detector in FIG. 2, wherein each correlation detector has the same configuration.

Looking at the configuration, the multiplier (1) to multiply the complex signal (Complex Rx Input) received from the antenna and the scramble code generated by the scramble code generator (2), and to despread the signal output through the multiplier (1) Non-Coherent Despreader (3) and Coherent Despreader (4), and through the respective despreaders (3, 4) for accumulating the energy value of the de-spread symbol through the first, It consists of two energy accumulators 5 and 6.

The energy output from the first and second energy accumulators 5 and 6 is input to the code and diversity detector 7 to determine the primary scramble code number and antenna diversity of the cell.

The synchronization and code group of the received signal required for the three-stage code search according to the present invention are provided through the first and second search processes, and the operation time of the three-stage search device is determined using the provided code group and timing information. 8 codes determined according to the selected code group are input to each correlation detector (100 to 107) to prepare for code generation, and when ready for operation, the received complex signal (I / Q) is input to each correlation detector (100 to 107). ).

Accordingly, each of the correlation detectors 100 to 107 performs a complex product with its own PN code generated by the scramble code generator 2 through the multiplier 1 through the input complex signal I / Q.

The value multiplied by the chip unit through the multiplier 1 includes a noncoherent despreader 3 for non-coherent detection and a coherent despreader for coherent detection. 4), despreading and energy detection in units of symbols are performed.

The energy output from each despreader (3, 4) is input to the first and second energy accumulators (5, 6) for the operation of the multi-symbol unit, respectively, if the energy accumulation operation is performed for a predetermined time, each correlation The final energy value output from the detectors 100 to 107 is input to the code and diversity detector 7 to determine the final code number and the presence or absence of antenna diversity.

FIG. 4 is a block diagram showing the detailed configuration of the non-coherent inverse spreader in FIG. 3, and is configured to inversely spread the antenna 1 signal on the transmitting side.

Looking at the configuration, a multiplier 32 for multiplying the descrambled complex input signal and the diversity pattern 1 signal, and a complex signal (I / Q) multiplied by the pattern 1 signal through the multiplier 32 The adder 33 accumulates the signal, a sampler 34 for switching the accumulated value in units of one symbol, and a first energy calculator configured to calculate an energy value in one symbol unit output from the sampler 34. It consists of 35.

Hereinafter, referring to the operation of the noncoherent despreader configured as described above, the signal descrambled from the multiplier 1 and output is multiplied by the diversity pattern 1 31 through the multiplier 32 and the adder 33. Is entered.

Here, the diversity pattern 1 is the same as the transmission symbol pattern of the antenna 1 shown in FIG.

The accumulator 33 individually accumulates the complex signal I / Q multiplied by the pattern 1 31, and the accumulated value is an energy calculation unit at one symbol (256 chip) period through the sampler 34. The energy calculator 35 calculates energy in symbol units and outputs the energy to the first energy accumulator 5.

In addition, the output of the sampler 34 is input to the coherent despreader 4 for coherent detection.

Accordingly, the coherent despreader 4 is used to coherently despread the signals of the antenna 1 and antenna 2 on the transmitting side.

FIG. 5 is a block diagram showing the detailed configuration of the coherent inverse spreader in FIG. 3, and is configured to inversely spread the antenna 2 signal on the transmitting side.

Looking at the configuration, a multiplier 42 for multiplying a descrambled complex input signal and a diversity pattern 2 signal, and a complex signal (I / Q) multiplied by a pattern 2 signal through the multiplier 42 An adder 43 for accumulating?, A sampler 44 for switching and outputting the accumulated value in units of one symbol, a second symbol buffer 46 for buffering symbol values output from the sampler 44; A first symbol buffer 45 for buffering a value output in units of one symbol from the non-coherent despreader, an adder 49 for summing respective symbols stored in the first and second symbol buffers 45 and 46; A sampler 47 for sampling and outputting the value added by the adder 49 in units of N symbols, a third energy calculator 48 for calculating energy of the value output through the sampler 47, and A despread symbol of antenna 1 stored in one symbol buffer 45 is added and output in units of N A sampler 50, a second energy calculator 51 that calculates energy of a value output through the sampler, and a despread symbol of antenna 2 stored in the second symbol buffer 46 are added and output in N units. And a fourth energy calculator 56 that calculates energy of a value output through the sampler.

Hereinafter, referring to the operation of the coherent despreader configured as described above, the signal descrambled from the multiplier 1 and output is multiplied by the diversity pattern 1 41 through the multiplier 42 to the adder 43. Is entered.

Here, the diversity pattern 2 is the same as the transmission symbol pattern of the antenna 2 shown in FIG.

The adder 43 individually accumulates the complex signal I / Q multiplied by the pattern 2, and the accumulated value is stored in the second symbol buffer 46 at one symbol (256 chip) period through the sampler 44. do.

In addition, the despread signal output in units of one symbol through the sampler 34 of the noncoherent despreader of FIG. 4 is stored in the first symbol buffer 45.

That is, the first symbol buffer 45 may store the symbol value obtained by coherent despreading of antenna 1, and the second symbol buffer 46 stores the symbol value obtained by coherent despreading of antenna 2. can see.

As described above, each symbol stored in the first and second symbol buffers 45 and 46 is added by the adder 49 and input to the third energy calculator 48 through the sampler 47 in units of N symbols.

Here, N is determined as a multiple of 2 greater than 0, and the sampler 47 outputs a value obtained by adding N antenna 1 symbols and antenna 2 symbols in units of N symbols.

The energy calculated by the third energy calculator 48 is coherent energy and is accumulated through the second energy accumulator 6 and input to the code and diversity detector 7.

The sampler 50 adds N despread symbols of the antenna 1 to the second energy calculator 51, and the output of the energy calculator 51 is the symbol energy of the antenna 1. Accumulated through and input to the code and diversity detector (7).

The sampler 52 adds N despread symbols of the antenna 2 to the fourth energy calculator 53, and the output of the energy calculator 51 is the symbol energy of the antenna 2. Accumulated through and input to the code and diversity detector (7).

For example, when the transmitting side does not use antenna diversity (Tx Diversity), and the value of the transmission symbol A is 1, and the number N of coherent despread symbol sums is 2, the antenna 2 is not transmitted.

Therefore, the transmission power gain of the antenna 1 is K, the transmission symbol patterns are 1, 1, ..., and the output of the sampler 50 is 2 per 2 symbols, and the output energy is 4K.

However, the output of the sampler 52 becomes a value of 0 per 2 symbols, and the output energy becomes 0K.

Thus, it can be seen that antenna diversity is not used.

In contrast, when Tx Diversity is used at the transmitting side, the transmit power gain per antenna is 0.5K, and symbols of A1 + A2, A1-A2, A1-A2, and A1 + A2 are transmitted.

Here, A1 is a pattern transmitted from antenna 1 and A2 is a pattern transmitted from antenna 2.

Therefore, when A1 and A2 are both 1, the output of the sampler 50 is 2, the output of the sampler 52 is also 2, and the final energy is 2K in both the antenna 1 and the antenna 2.

As a result, the energy generated by the two antennas is comparable and it can be estimated that antenna diversity is used.

FIG. 6 is a flowchart illustrating a process for determining diversity in a code and diversity detector according to the present invention, and illustrates a process for detecting code number and diversity based on an energy value output from each correlation detector.

Referring to this, the code and diversity detector waits for the correlation operation to be completed from each correlation detector (S101), detects a maximum energy value from _non-coherent energy (E _non-coherent ), and then _stores the energy of antenna 1 (E Antenna 1). It is determined whether or not the value (| E _Antenna1 -E _Antenna2 |) taking an absolute value to the difference value between the energy E _Antenna2 and the antenna 2 is greater than or equal to the predetermined energy alpha1 (S103).

As a result of the determination, if the difference between the energy of the antennas 1 and 2 (| E _Antenna1 -E _Antenna2 |) is equal to or greater than the predetermined energy alpha1, antenna diversity is not used, and the code number at that time is M _non-coherent . (S104).

However, if the difference between the energy of the antennas 1 and 2 (| E _Antenna1 -E _Antenna2 |) is smaller than the predetermined energy alpha1, the maximum energy value is detected from the coherent energy E _coherent (S105), and the antenna 1 It is determined whether or not the value (| E _Antenna1 -E _Antenna2 |) which takes an absolute value to the difference value between the energy E _Antenna1 of the antenna E and the energy E _Antenna2 of the antenna 2 is less than or equal to the predetermined energy alpha2 (S106).

As a result of the determination, if the difference value || E _Antenna1 -E _Antenna2 | of the antennas 1 and 2 is less than or equal to the predetermined energy alpha2, antenna diversity is used, and the code number at that time becomes M _coherent ( S107).

However, if the difference between the energy of the antennas 1 and 2 (| E _Antenna1 -E _Antenna2 |) is greater than the predetermined energy alpha2, the code number found in the coherent mode (E _coherent ) and the code number found in the noncoherent mode ( It is determined whether E _non-coherent ) is the same value (S108).

As a result of the determination, if the two code number values are the same, it is determined whether the diversity information acquired in steps 1 and 2 is available (S109), and if available, the code number is determined as M _coherent , Use already obtained (S110).

If the two energy values are different or diversity information is not obtained in steps 1 and 2, the search process is performed again (S111).

Here, the diversity detection reference values alpha1 and alpha2 are set to appropriate values by experiment in consideration of the reception noise level.

In addition, M _non-coherent is a scramble code number obtained through _non-coherent energy detection, M _coherent is a scramble code number obtained through coherent energy detection.

In addition, when the detection of diversity cannot be confirmed from the present invention in the condition control of the last step, when the scramble codes obtained in the coherent method and the non-coherent method are the same, and there is information already obtained in the first and second search. The code number is used as the result of the three-stage search, and the antenna diversity is used as the result of the first and second search.

As described above, the apparatus and method for detecting antenna diversity of a mobile communication system according to the present invention is an antenna diversity detected during a three-stage code search of an asynchronous mobile communication system or a search for one and two steps. Tx Diversity) can be verified.

Claims (7)

In the cell search device of the asynchronous mobile communication system, A plurality of correlation detectors for receiving a complex signal (I / Q) received from an antenna to obtain a time diversity effect; And a code and diversity detector for determining a code number and antenna diversity based on energy values detected through the plurality of correlation detectors. 2. The apparatus of claim 1, wherein the correlation detector comprises: a multiplier for multiplying a scramble code with a complex signal received from an antenna; A noncoherent inverse diffuser and a coherent inverse diffuser for despreading the signal output through the multiplier; And first and second energy accumulators for accumulating energy values of symbols despread through the respective despreaders. 3. The apparatus of claim 2, wherein the noncoherent inverse spreader comprises: a multiplier for multiplying a diversity pattern 1 signal by a descrambled output signal; An adder for accumulating a complex signal (I / Q) multiplied by a pattern 1 signal through the multiplier; A sampler for switching and outputting the accumulated value by one symbol unit; And a first energy calculator configured to calculate an energy value of one symbol unit output from the sampler. In code search and antenna diversity detection of asynchronous mobile communication system, Performing a correlation operation on the received complex signal; If the correlation operation is completed, the absolute value of the difference value of the energy of the antenna 1 (E _Antenna1) and energy (E _Antenna2) of the antenna _{2 (| E Antenna1 - E Antenna2} |) obtaining a and; And detecting diversity based on whether the absolute value (| E _Antenna1 -E _Antenna2 |) is equal to or greater than a predetermined energy alpha1 or equal to or less than a predetermined energy alpha2. City detection method. The method of claim 4, wherein the absolute value of the difference value of the energy (E _Antenna1) and energy (E _Antenna2) of the antenna 2 of the antenna _{1 (| E Antenna1 - E Antenna2} |) if more than a specified energy (alpha1), antenna It is determined that diversity is not used, and the code number (M _non-coherent ) at that time is the number of scramble codes corresponding to the maximum energy value detected in _non-coherent energy (E _non-coherent ). Antenna diversity detection method of mobile communication system. The method of claim 4, wherein the absolute value of the difference value of the energy (E _Antenna1) and energy (E _Antenna2) of the antenna 2 of the antenna _{1 (| E Antenna1 - E Antenna2} |) is not more than a certain energy (alpha2), the antenna It is determined that diversity is used, and the code number M _{coherent at} that time is the number of scramble codes corresponding to the maximum energy value detected in the coherent energy E _coherent . City detection method. The mobile communication method of claim 4, further comprising re-enabling the antenna diversity search if the two code numbers are different when the antenna diversity is out of the condition for detecting the antenna diversity. Antenna diversity detection method of system.