KR100498957B1 - Apparatus and method for searching preamble in a wcdma mobile communication system - Google Patents

Abstract

The present invention proposes an apparatus and method for searching for a preamble used for allocation of a reverse common channel in an asynchronous code division multiple access mobile communication system. To this end, in the present invention, the correlation values for each symbol output by Hadamard transformation are stored in a buffer, and the correlation values output by the next Hadamard transformation are added to the correlation values stored in the buffer. Therefore, the total correlation length can be adjusted by determining the number of times the output correlation values and the accumulated correlation values are added.

Description

Preamble Searching Device and Method in Asynchronous Mobile Communication System {APPARATUS AND METHOD FOR SEARCHING PREAMBLE IN A WCDMA MOBILE COMMUNICATION SYSTEM}

The present invention relates to an apparatus and method for receiving a reverse common channel in a code division multiple access mobile communication system, and more particularly, to an apparatus for searching for a preamble used for allocation of a reverse common channel in an asynchronous code division multiple access mobile communication system. It is about a method.

In general, mobile communication systems can be roughly divided into synchronous and asynchronous. In the meantime, the asynchronous method is a method proposed in Europe, and the synchronous method is a method proposed in the United States.

In addition, with the rapid growth of the mobile communication industry, mobile communication systems are emerging as next generation mobile communication systems capable of providing services such as data and video as well as normal voice services. However, as mentioned above, the United States and Europe, which implement mobile communication systems in different ways, are working on different types of standardization. Among them, 3GPP W-CDMA mobile communication system (3rd generation partnership project wideband code division multiple access communication system) is a European next generation mobile communication system.

A channel in the W-CDMA mobile communication system consists of a physical channel and a logical channel mapped on one or more physical channels. The logical channel is divided into a control channel, a common channel, a dedicated control channel and a traffic channel according to the purpose of use. Meanwhile, in the W-CDMA mobile communication system, there are a random access channel (hereinafter referred to as "RACH") and a common packet channel (hereinafter referred to as "CPCH") as a reverse common channel. The reverse common channel is a channel allocated by the base station at the request of a mobile station (hereinafter referred to as "UE"). That is, a series of procedures with a base station are required for the UE to be allocated the reverse common channel.

As an example, FIG. 1 illustrates a communication signal transmission / reception relationship of the RACH among the conventional reverse common channels.

Referring to FIG. 1, reference numeral 151 denotes a signal transmission procedure of a reverse channel by a UE, and reference numeral 111 denotes a signal transmission procedure of a forward channel by a base station (hereinafter referred to as "Node B"). When the UE needs to transmit data through the RACH, the UE transmits an access preamble (hereinafter referred to as "AP") 162 to the Node B. The AP 162 is a signal that the UE requests to allocate the RACH to the Node B, and is a signal generated by arbitrarily selecting one of a plurality of RACH signatures. When the preamble spreading code used for the AP has 256 chip periods and the chip rate is 4.096 Mcps, the length of the AP may be set to 1 ms. The 16 kinds of signatures that can be selected by the UE are as shown in Table 1 below.

Preamble symbol Signature P0 P1 P2 P3 P4 P5 P6 P7 P8 P9 P10 P11 P12 P13 P14 P15 One A A A -A -A -A A -A -A A A -A A -A A A 2 -A A -A -A A A A -A A A A -A -A A -A A 3 A -A A A A -A A A -A A A A -A A -A A 4 -A A -A A -A -A -A -A -A A -A A -A A A A 5 A -A -A -A -A A A -A -A -A -A A -A -A -A A 6 -A -A A -A A -A A -A A -A -A A A A A A 7 -A A A A -A -A A A A -A -A -A -A -A -A A 8 A A -A -A -A -A -A A A -A A A A A -A A 9 A -A A -A -A A -A A A A -A -A -A A A A 10 -A A A -A A A -A A -A -A A A -A -A A A 11 A A A A A A -A -A A A -A A A -A -A A 12 A A -A A A A A A -A -A -A -A A A A A 13 A -A -A A A -A -A -A A -A A -A -A -A A A 14 -A -A -A A -A A A A A A A A A -A A A 15 -A -A -A -A A -A -A A -A A -A -A A -A -A A 16 -A -A A A -A A -A -A -A -A A -A A A -A A

As shown in Table 1, each signature consists of 16 preamble symbols, each of which consists of a preamble spreading code of 256 chip periods. As the preamble spreading code, a gold code having a 256 chip period is used. In Table 1, A may be expressed as '1 + j'. As illustrated in Table 1, there are 16 types of signatures for distinguishing when a plurality of UEs access the system at the same time. For this purpose, the signatures are orthogonal to each other.

When the Node B receives the AP 162, the Node B transmits the signature of the AP 162 to the UE through an Access Preamble Acquisition Indicator Channel (hereinafter referred to as "AICH"). . The AICH is a channel received and responded to by the UMTS Terrestrial Radio Access Network (hereinafter referred to as "UTRAN") to the AP 162.

The UE checks whether a signature transmitted by the UE is detected through the AICH in response to the AP 162. If the UE does not detect the signature through the AICH within the set time (τ _pp ) after transmitting the AP 162, it determines that the UTRAN did not detect the preamble transmitted by the UE and retransmits the AP. At this time, the retransmission AP 164 is transmitted with power increased by ΔP (dB) than the power of the AP 162 previously transmitted. The signature used for the retransmission AP 164 is a randomly selected one of the other signatures defined in the ASC selected by the UE. However, when the signature used for the AP 162 is detected, the UE determines that the preamble is detected by the UTRAN and transmits a RACH message. In this case, the RACH message is spread with the preamble spreading code used for transmitting the signature and transmitted.

As described above, the UE selects an access service class (hereinafter referred to as "ASC") according to the type of data to be transmitted, and the RACH sub_channel group defined in the ASC; The AP is used to obtain a license from the UTRAN for the RACH.

On the other hand, the CPCH signal transmission procedure of the reverse common channels in addition to the transmission method of the AP used in the above-described RACH signal transmission procedure, the collision detection preamble (CPCH) signals from different UEs to avoid collisions; Collision Detection preamble: hereinafter referred to as "CD-P").

As described above, as the UE transmits an AP to request allocation of a conventional reverse common channel, a Node B requires a preamble searcher for receiving the AP. The preamble searcher calculates correlation values of all preamble spreading codes as the AP is scrambled by a predetermined preamble spreading code, and accumulates 16 preamble symbols obtained through the AP to detect the AP.

2 illustrates a configuration of a preamble receiving apparatus including a conventional preamble finder. As shown in FIG. 2, the preamble finder 210 is configured as a plurality of APs for parallel processing of APs received through an I channel and a Q channel. The preamble searcher 210 receives the preamble transmitted from the UE by correlating all preamble spreading codes that can be used in the UE with respect to the preamble spread and transmitted by a predetermined preamble spreading code from the UE.

Referring to FIG. 2, the AP received from the UE is provided to the antenna buffer 214 after the phase shift is performed by the phase shifter 212. The 1ms preamble transmission signal transmitted from the UE has a structure in which 16 symbols represented by Equation 1 are repeated a predetermined number of times.

Can be.

Here, C _k indicates a preamble spreading code of 256 chip periods, and P _c (t) indicates a rectangular function having a size of 1 / T _c and a length T _c . Repeating the 16 symbols a predetermined number of times is called symbol spreading. On the other hand, the symbols repeated a predetermined number of times are scrambled by a scrambling code for identifying the mobile terminal is transmitted as a chip signal.

The antenna buffer 214 has a recording area larger than the entire tap period used by the matching filter 216, and stores the received signal provided through the phase shifter 212 and then matches the matching filter 216. Will be printed sequentially. In this case, the signal output from the antenna buffer 214 is referred to as a chip signal. As an example, assuming that the signature selected by the mobile terminal is composed of 16 symbols, and the 16 symbols are repeatedly transmitted 256 times, the chip signal received by the base station is composed of 4096 chips. In this case, the antenna buffer 214 has a size smaller than the 4096 chip (for example, 3072 chips). The scrambling code generator 220 generates scrambling codes used to distinguish the mobile terminal in transmitting the AP and provides the scrambling code to the matching filter 216. The matched filter 216 is provided from the antenna buffer 214 by 16 symbols of each of the scrambling codes provided from the scrambling code generation unit 220 and all signatures selectable by mobile terminals. Correlated values for each symbol are output from the chip signal. Unlike the correlator, the matched filter 216 outputs a correlation value every chip unit. The non-interference accumulator 218 accumulates the correlation value for the preamble of 1 ms by receiving the symbols from the matched filter 216 and accumulating 16 symbols corresponding to the number of symbols constituting the preamble. do. Correlation values provided from the plurality of preamble seekers 210 are provided to the combining processor 230, and the combining processor 230 combines the plurality of correlation values and outputs the combined values. Meanwhile, when a plurality of antennas are used, the combining processor 230 combines and outputs correlation values provided for each antenna. The energy classifier 240 classifies and outputs correlation values from the combining processor 230 in order of energy magnitude. The correlation values classified and output from the energy classifier 240 in the order of energy are registered in the candidate table 250 and then recorded in the report table 260 to be accessed by the digital signal processor.

3 is a diagram illustrating a specific example of the matched filter in FIG. 2.

Referring to FIG. 3, the delayers D ₀ to D _{M / N-1} sequentially buffer chip signals input in chip units. The number of delays is determined by M / N. M is the maximum number of chips that can be correlated, and assuming that the mobile terminal repeatedly transmits a signature of 16 symbols 256 times, the total number of chips is 4096, which is M. N is a constant value determined by the performance of the system. In order to improve the performance of the system, M should have a value close to 1, otherwise M may have a large value to increase the number of search target mobile terminals for searching for a preamble. The case where M is set to a large value is also applicable when the number of antennas increases. As an example, when N is set to 4, i.e., when processing signals received by four mobile terminals or four antennas, the N is configured with 1024 delays. In the following description, it is assumed that an example implemented with 1024 delay units is assumed. Each of the delayers inputs the received chip signal to the next delay unit in chip units. When chip signals are stored in each of the 1024 delayers, 1024 chip signals stored in each of the delayers are stored in the same symbol every 16 cycles. That is, the 1024 chip signals have a structure in which the first 16 chip signals are repeated 64 times. This is caused by the mobile station repeatedly transmitting 16 symbols 256 times.

Multipliers and adders 310-1 through 310-16 each input the same 64 needle signals and a scrambling code from the delayers. The multipliers and adders 310-1 to 310-16 multiply each of the 64 chip signals by the scrambling code, and add 16 output values output by the multiplication to correspond to the 64 chip signals. Outputs the energy value of the symbol. More specifically, the multiplier and the adder 310-1 are output from a total of 64 delayers (D ₁₆ , D ₃₂ ,...) That are positioned at 16 cycles starting with the first delay D ₀ . 64 chip signals are input. The 64 chip signals input to the multiplier and adder 310-1 correspond to the first symbol of the 16 symbols constituting the signature. The multiplier and the adder 310-2 is two in the second delay group delay which is located the 16 cycles to a D ₁ to the beginning _{(D 17, D 33, ...} ), 64 of chip signal output from the total of 64 delay groups As input. The 64 chip signals input to the multiplier and adder 310-2 correspond to the second symbol of the 16 symbols constituting the signature. Finally, the multiplier and adder 310-16 outputs 64 delays (D ₃₁ , D ₄₇ , ...), which are located at the 16th cycle starting with the sixteenth delay D ₁₅ . Two chip signals are input. The 64 chip signals input to the multiplier and adder 310-16 correspond to the last symbol of the 16 symbols constituting the signature. Meanwhile, the multipliers and adders 310-1 to 310-16 output energy values for each symbol whenever the chip signals are delayed by the delayers once.

The 16 symbolic energy values output from the multipliers and adders 310-1 to 310-16 are provided to the Hadamard converter 320. The Fast Hadamard Transform (FHT) 320 correlates with each of the energy values as symbols of all signatures that can be selected at the mobile terminal. That is, the preamble transmitted from the mobile station can be detected by calculating a correlation value between the 16 symbols of each of the signatures and the respective energy values. That is, the Hadamard converter 320 determines that the preamble transmitted from the mobile terminal has the specific signature when the energy values have the maximum correlation value for the specific signature. The correlation value can be obtained by taking a correlation between the energy value of each symbol and the preamble spreading code used for spreading for each symbol.

As described above, regardless of the size of the buffer for temporarily storing the received signal, the maximum correlation length for searching the preamble cannot exceed the range of the entire tap period. That is, the maximum correlation length that can search the preamble is equal to the length of the entire tap interval. In addition, the maximum window size for searching the preamble is determined by the difference between the minimum correlation length and the size of the buffer for temporarily storing the received signal. Therefore, in order to enlarge the window size, the capacity of the buffer for temporarily storing the received signal must be increased, which causes a problem of hardware loss. As described above, there is a limit in operating the preamble search apparatus by extending the correlation length and the window size.

Accordingly, an object of the present invention to solve the above problems is to provide a preamble searching apparatus and method for increasing the detection probability of an access preamble by calculating the correlation with the preamble spreading codes by the maximum correlation length.

Another object of the present invention is to provide a search apparatus and method for detecting an access preamble by determining a window size according to a preamble search condition.

In a first aspect for achieving the above object, the present invention provides a signature of one of a plurality of signatures consisting of k symbols spread by a predetermined preamble spreading code when an assignment of a reverse common channel is required. And a plurality of mobile terminals for selecting and transmitting the plurality of symbols constituting the signature to an access preamble by a predetermined number of times, and a base station for receiving the access preamble and allocating the reverse common channel. An apparatus for searching for the access preamble by a base station in a communication system, the apparatus comprising: inputting symbols having a predetermined tap length to calculate energy values for each of the k symbols, and correlating values of the respective energy values with the k symbols. A symbol acquiring unit for calculating and outputting the data and a correlation value from the symbol acquiring unit And the characterized in that the buffer for storing the symbols by k, by adding by the previous correlation values and symbols stored in the correlation values from the symbol acquisition unit in the buffer includes an adder provided in the buffer.

In a second aspect for achieving the above object, the present invention provides a signature of one of a plurality of signatures consisting of k symbols spread by a predetermined preamble spreading code when an assignment of a reverse common channel is required. And a plurality of mobile terminals for selecting and transmitting the plurality of symbols constituting the signature to an access preamble by a predetermined number of times, and a base station for receiving the access preamble and allocating the reverse common channel. A method of searching for the access preamble by a base station in a communication system, the method comprising: calculating energy values for each of the k symbols by inputting symbols having a predetermined tap length, and correlating values of the respective energy values and the k symbols. Calculating and outputting the data, and storing the correlation values in a buffer. It characterized in that by adding correlation values for each symbol and includes the step of re-stored in the buffer.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

In the detailed description of the present invention to be described later, the present invention stores correlation values for each symbol output by Hadamard transformation in a buffer, and adds arithmetic values output by the next Hadamard transformation with correlation values stored in the buffer. A preamble searching device and method will be posted. Therefore, the total correlation length can be adjusted by determining the number of times the output correlation values and the accumulated correlation values are added.

4 is a diagram illustrating a configuration of a preamble searching apparatus according to an embodiment of the present invention. As shown in FIG. 4, according to an embodiment of the present invention, an adder 430 comprising adders corresponding to the number of correlation values output in parallel from the Hadamard transform unit 420 in the existing preamble searching apparatus, It has a structure in which a buffer for buffering the output from the adder 430 is added. Therefore, in the detailed description to be described later, a detailed description of the configuration overlapping with the existing preamble searching apparatus will be omitted.

Hereinafter, referring to FIG. 4, a preamble searching apparatus according to an exemplary embodiment of the present disclosure is provided with symbol-related correlation values from the Hadamard transformer 420 that constitutes a conventional preamble searching apparatus. The correlation values output for each symbol are provided as inputs of corresponding adders. If the correlation values are correlation values initially output from the Hadamard converter 420, each of the adders of the adder 430 may output the input correlation values as they are. The correlation values output from the adder 430 are stored in the buffer 440. However, if the correlation values output from the Hadamard transform unit 420 are not the first ones, correlation values for each symbol stored in the buffer 440 may be provided as another input of the adder 430. Each of the adders of the adder 420 adds the correlation values provided from the Hadamard transform unit 420 and the correlation values provided from the buffer 440 for each symbol and stores them in the buffer 440. Therefore, the correlation values accumulated in a predetermined section are stored in the buffer 440. Meanwhile, when it is determined that all correlations for each symbol are made in the desired window size, the buffers 440 output correlation values stored for each symbol in the buffer 440.

An example of an operation according to an exemplary embodiment of the present invention will be described with reference to the above-described configuration. In an example of an operation to be described below, it is assumed that the total number of chips received is 4096, the tap period is 1024, and the window size is 2048.

Among the 4096 chips c ₀ to c ₄₀₉₅ received, 1024 chips c ₀ to c ₁₀₂₃ corresponding to the tap period are sequentially stored in the _delayers D ₀ to D ₁₀₂₃ . In such a situation, when the next chip signal c ₁₀₂₄ is input, each of the _delayers D ₀ to D ₁₀₂₃ outputs chip signals c ₀ to c ₁₀₂₃ which are currently stored. The c ₀ to c ₁₀₂₃ output from each of the delayers D ₀ to D ₁₀₂₃ are provided to corresponding multipliers and adders among the multipliers and adders 410-1 to 410-16.

Chip signals c ₁₆ , c ₃₂ , c ₄₈ , c ₆₄ , c ₈₀ , c ₉₆ , c ₁₁₂ , ..., c ₉₇₆ , c that are multiples of 16 based on c ₀ of c ₀ to c _{1023 992} , c ₁₀₀₈ ) are provided as inputs to the multiplier and adder 410-1. Chip signals c ₁₇ , c ₃₃ , c ₄₉ , c ₆₅ , c ₈₁ , c ₉₇ , c ₁₁₃ , ..., c ₉₇₇ , c multiplied by 16 based on c ₁ of c ₀ to c _{1023 993} , c ₁₀₀₉ ) are provided as inputs to the multiplier and adder 410-2. Chip signals c ₁₈ , c ₃₄ , c ₅₀ , c ₆₆ , c ₈₂ , c ₉₈ , c ₁₁₄ , ..., c ₉₇₈ , c that are multiples of 16 based on c ₂ of c ₀ to c ₁₀₂₃ . ₉₉₄ , c ₁₀₁₀ ) is provided as input to the multiplier and adder 410-3. Chip signals c ₁₉ , c ₃₅ , c ₅₁ , c ₆₇ , c ₈₃ , c ₉₉ , c ₁₁₅ , ..., c ₉₇₉ , c that are multiples of 16 based on c ₃ of c ₀ to c _{1023 995} , c ₁₀₁₁ ) is provided as input to the multiplier and adder 410-4. Chip signals c ₂₀ , c ₃₆ , c ₅₂ , c ₆₈ , c ₈₄ , c ₁₀₀ , c ₁₁₆ , ..., c ₉₈₀ , c multiplied by 16 based on c ₄ of c ₀ to c _{1023 996} , c ₁₀₁₂ ) are provided as inputs to the multiplier and adder 410-5. Chip signals c ₂₁ , c ₃₇ , c ₅₃ , c ₆₉ , c ₈₅ , c ₁₀₁ , c ₁₁₇ , ..., c ₉₈₁ , c that are multiples of 16 based on c ₅ of c ₀ to c _{1023 997} , c ₁₀₁₃ ) are provided as inputs to the multiplier and adder 410-6. Chip signals c ₂₂ , c ₃₈ , c ₅₄ , c ₇₀ , c ₈₆ , c ₁₀₂ , c ₁₁₈ , ..., c ₉₈₂ , c multiplied by 16 based on c ₆ of c ₀ to c _{1023 998} , c ₁₀₁₄ ) are provided as inputs to the multiplier and adder 410-7. Chip signals c ₂₃ , c ₃₉ , c ₅₅ , c ₇₁ , c ₈₇ , c ₁₀₃ , c ₁₁₉ , ..., c ₉₈₃ , c multiplied by 16 based on c ₇ of c ₀ to c _{1023 999} , c ₁₀₁₅ ) is provided as input to the multiplier and adder 410-8. Chip signals c ₂₄ , c ₄₀ , c ₅₆ , c ₇₂ , c ₈₈ , c ₁₀₄ , c ₁₂₀ , ..., c ₉₈₄ , c multiplied by 16 based on c ₈ of c ₀ to c _{1023 1000} , c ₁₀₁₆ ) are provided as inputs to the multiplier and adder 410-9. Chip signals c ₂₅ , c ₄₁ , c ₅₇ , c ₇₃ , c ₈₉ , c ₁₀₅ , c ₁₂₁ , ..., c ₉₈₅ , c having multiples of 16 based on c ₉ of c ₀ to c _{1023 1001} , c ₁₀₁₇ ) is provided as input to the multiplier and adder 410-10. Chip signals c ₂₆ , c ₄₂ , c ₅₈ , c ₇₄ , c ₉₀ , c ₁₀₆ , c ₁₂₂ , ..., c ₉₈₆ , c that are multiples of 16 based on c ₁₀ of c ₀ to c _{1023 1002} , c ₁₀₁₈ ) is provided as input to the multiplier and adder 410-11. Chip signals c ₂₇ , c ₄₃ , c ₅₉ , c ₇₅ , c ₉₁ , c ₁₀₇ , c ₁₂₃ , ..., c ₉₈₇ , c that are multiples of 16 based on c ₁₁ of c ₀ to c _{1023 1003} , c ₁₀₁₉ ) is provided as input to the multiplier and adder 410-12. Chip signals c ₂₈ , c ₄₄ , c ₆₀ , c ₇₆ , c ₉₂ , c ₁₀₈ , c ₁₂₄ , ..., c ₉₈₈ , c that are multiples of 16 based on c ₁₂ of c ₀ to c _{1023 1004} , c ₁₀₂₀ ) is provided as input to the multiplier and adder 410-13. Chip signals c ₂₉ , c ₄₅ , c ₆₁ , c ₇₇ , c ₉₃ , c ₁₀₉ , c ₁₂₅ , ..., c ₉₈₉ , c multiplied by 16 based on c ₁₃ of c ₀ to c _{1023 1005} , c ₁₀₂₁ ) is provided as input to the multiplier and adder 410-14. Chip signals c ₃₀ , c ₄₆ , c ₆₂ , c ₇₈ , c ₉₄ , c ₁₁₀ , c ₁₂₆ , ..., c ₉₉₀ , c that are multiples of 16 based on c ₁₄ of c ₀ to c _{1023 1006} , c ₁₀₂₂ ) are provided as inputs to the multiplier and adder 410-15. Chip signals c ₃₁ , c ₄₇ , c ₆₃ , c ₇₉ , c ₉₅ , c ₁₁₁ , c ₁₂₇ , ..., c ₉₉₁ , c multiplied by 16 based on c ₁₅ of c ₀ to c _{1023 1007} , c ₁₀₂₃ ) is provided as input to the multiplier and adder 410-16.

The chip signals provided to the multipliers and the adders 410-1 to 410-16 are multiplied and output by the plurality of multipliers provided in the multipliers and the adders 410-1 to 410-16. The scrambling code is a code for identifying a mobile terminal. The symbols output by the multipliers are added by the adders provided in the multipliers and the adders 410-1 to 410-16, respectively, and are output as one symbol. Sixteen symbols output from each of the multipliers and the adders 410-1 to 410-16 are provided to the Hadamard converter 420. The Hadamard converter 420 measures a correlation between the sixteen symbols and symbols of all signatures that can be selected by the mobile terminals, and outputs a correlation value for each of the sixteen symbols. The 16 correlation values output for each symbol are provided to corresponding adders among the adders constituting the adder 430. Each of the adders adds the correlation values of each symbol provided from the buffer 440 to the correlation values provided from the Hadamard converter 420 and outputs the correlation values. However, if there is no correlation value provided from the buffer 440, the correlation value provided from the Hadamard transformer 420 is output as it is. The correlation values output from the respective adders are provided to the buffer 440 and stored for each symbol. The buffer 440 provides the adder 430 with the correlation values currently stored in the period in which the delay occurs. Therefore, the buffer 440 accumulates the correlation values provided by the Hadamard transform unit 420 for each symbol. The number of times a correlation value is accumulated in units of chips by the adder 430 and the buffer 440 is determined by a window size to be measured. As previously assumed that the window size is 2048, the cumulative number is 1024. The buffer 440 outputs 16 final correlation values accumulated for each symbol when the correlation values are accumulated as many as the accumulation times.

In the above-described embodiment, the number of antennas or the number of mobile terminals to be searched are not considered. If the number of antennas or mobile terminals is considered, the maximum correlation length and window size for each antenna or each mobile terminal should be adjusted by the number of antennas or mobile terminals.

As described above, the present invention can not only arbitrarily set the correlation length according to the reception conditions of the preamble in the base station, but also can change the window size, so that it is possible to flexibly cope with fast initial synchronization acquisition and various requirements of the operator. Has

1 illustrates an example of a conventional reverse common channel allocation procedure.

2 is a diagram illustrating a configuration of a preamble searching apparatus in a base station of a conventional asynchronous mobile communication system.

3 is a view showing a detailed configuration of the matched filter in FIG.

4 is a diagram illustrating a detailed configuration of a matched filter for preamble searching in a base station of an asynchronous mobile communication system according to an embodiment of the present invention.

Claims (8)

When the assignment of the reverse common channel is required, an access preamble is selected by selecting one signature among a plurality of signatures consisting of k symbols spread by a predetermined preamble spreading code, and repeating a plurality of symbols constituting the signature a predetermined number of times. Claims [1] An apparatus for searching for an access preamble in a code division multiple access mobile communication system, comprising: a plurality of mobile terminals transmitting to the mobile station; and a base station receiving the access preamble and allocating the reverse common channel. A symbol obtaining unit configured to input symbols having a predetermined tap length, calculate energy values for each of the k symbols, calculate and output correlation values of the respective energy values and the k symbols, and A buffer for storing correlation values from the symbol acquisition unit for each of the k symbols; And adders for adding correlation values from the symbol obtainer to symbols and the previous correlation values stored in the buffer for each symbol. 2. The apparatus of claim 1, wherein the total correlation length for obtaining final correlation values from the access preamble is determined by adjusting the cumulative addition number by the adder. 2. The apparatus of claim 1, wherein the size of the buffer is equal to the product of the predetermined tap length and the number of tap delay lines. The apparatus of claim 3, wherein the number of tap delay lines is determined by the number of search target mobile terminals and the number of antennas. When the assignment of the reverse common channel is required, an access preamble is selected by selecting one signature among a plurality of signatures consisting of k symbols spread by a predetermined preamble spreading code, and repeating a plurality of symbols constituting the signature a predetermined number of times. In the code division multiple access mobile communication system including a plurality of mobile terminals to transmit to the base station for receiving the access preamble and assigning the reverse common channel, the method for the base station to search for the access preamble, Calculating energy values for each of the k symbols by inputting symbols having a predetermined tap length, and calculating and outputting the respective energy values and correlation values of the k symbols; And re-storing the correlation values in the buffer by adding the correlation values to symbols and the previous correlation values stored in the buffer. 6. The method as claimed in claim 5, wherein the total correlation length for obtaining final correlation values from the access preamble is determined by adjusting the cumulative addition number by the adder. 6. The method of claim 5, wherein the size of the buffer is equal to the product of the predetermined tap length and the number of tap delay lines. The method as claimed in claim 7, wherein the number of tap delay lines is determined by the number of search target mobile terminals and the number of antennas.