KR20030062810A - transmission and receiving method and receiving apparatus for synchronization word using Polarization module in CDMA Communication system - Google Patents

Abstract

PURPOSE: A method and apparatus for transmitting and receiving synchronization word using a polarity modulation in a CDMA communication system are provided to reduce a call drop probability when a mobile station is in a handoff by obtaining synchronization through searching a polarity-modulated synchronization word. CONSTITUTION: A serial/parallel converter(301) parallel-converts a signal of a common pilot channel and converts it into an I-channel and Q-channel data. First and second multipliers(303,305) spreads the I-channel and Q-channel data. A third multiplier phase-shifts the Q-channel spread data by 90 degree. A first adder(309) adds outputs of the first multiplier(303) and the third multiplier(307) and generates a complex-spread add signal. Gain controllers(311,313) multiply different gain control signals to the add signal. A first accumulator(315) accumulates gain-controlled channel signals and output them. A fifth multiplier(317) multiply an output of the first accumulator(315) and a scrambling code signal. A polarity modulator(318) uses a polarity modulation to a first synchronization channel. A second accumulator(323) accumulates an output of the fifth multiplier(317) and an output of a sixth multiplier(319). A seventh multiplier(321) multiplies a second synchronization channel by a second synchronization channel gain control signal, and outputs it to a second accumulator(323). An output of the second accumulator(323) is separated by a real number/complex number separator(325) and a baseband signal is filtered by pulse shaping units(327,329). Eighth and ninth multipliers(331,333) multiply outputs of the pulse shaping units(327,329) and corresponding carriers, and output them.

Description

Transmission and receiving method and receiving apparatus for synchronization word using Polarization module in CDMA Communication system}

In the code division multiple access system, in particular, a specific modulation channel can be transmitted by polarity modulation using a polarity code defined for distinguishing a scrambling group code to a specific synchronization channel among two different synchronization channels. The present invention relates to a synchronization word transmission and reception method using a polarization modulation and a receiving apparatus in a code division multiple access communication system in which a receiving unit can identify a code group ID using the polarity modulated synchronization channel.

Specifically, by using polarization modulation on the first synchronization channel commonly used by all base stations, slot synchronization acquisition and frame is performed so that the polarity-modulated first synchronization channel can be transmitted and the receiver can acquire synchronization with the base station. The present invention relates to a synchronization word transmission and reception method using polarity modulation and an apparatus thereof in an asynchronous code division multiple access communication system capable of identifying a synchronization, code group ID, and scrambling code, thereby reducing cell search time. In addition, polarity modulation is performed in a code division multiple access communication system in which one of 16 second synchronization codes is selected and a polarity modulation is transmitted to each second synchronization code using a polarity code defined to distinguish a scrambling group code. A synchronization word transmission and reception method and apparatus therefor are used.

The IMT-2000 system standard can be largely divided into synchronous and asynchronous. The biggest difference between the two methods is that the synchronization method acquires synchronization between base stations using the Global Positioning System (GPS). In contrast, the asynchronous method does not acquire special synchronization between base stations.

In particular, the synchronous method uses an offset of one long scrambling code to distinguish the base station, and thus has a shorter cell search time than the asynchronous method. However, there is a disadvantage in inflexibility when designing a base station because a specific external timing source such as GPS is required.

In contrast, the asynchronous scheme does not require synchronization between base stations and therefore does not require a specific external timing source. In addition, when designing a hierarchical cell structure in which indoor pico cells and micro cells exist, flexibility is excellent.

However, by using different 512 scrambling codes to distinguish the base station, the cell search time is long, and the receiver has a complex disadvantage. Currently, the system proposed by 3GPP as an asynchronous standard is W-CDMA (Wideband Code Division Multiple Access). In addition, W-CDMA specifies a three-step cell search method as a cell search method.

In current W-CDMA, a three-step cell search is performed to obtain synchronization with a base station in a mobile station. The three-stage cell search method can be divided into PN chip synchronization, slot synchronization, and frame synchronization. This allows the signal transmitted from the transmitter to the PN chip, slot, and frame unit and the receiver's operation on the signal in time. Means that.

1 and 2 are diagrams showing the configuration of a conventional W-CDMA transmitter and receiver.

FIG. 1 is a configuration diagram of a W-CDMA transmitter. A serial to parallel converter 101 converts an input common pilot channel signal in parallel to I and Q channel data. The first and second multipliers 103 and 105 spread common pilot data separated into respective I and Q channels using channel spread codes Cch, SF and m. The third multiplier (or phase shifter) 107 shifts the spread data of the Q channel by 90 degrees. The adder 109 adds and complexes the outputs of the first multiplier 103 and the third multiplier 107. A spread addition signal I + jQ is generated.

The gain adjusters 111 to 113 multiply the gain signals of the adder 109 by different gain control signals G1, ..., G2, respectively, wherein the gain control signals G1, ..., G2 This is a signal for controlling the transmission power of the signal transmitted through each channel and controlling the presence or absence of a channel.

The first accumulator 115 accumulates and outputs channel signals whose gains are adjusted by the gain controllers 111 to 113. The fifth multiplier 117 multiplies the output of the first accumulator 115 by the scrambling code signal Sdl, n, and the sixth multiplier 119 performs the first synchronous channel signal P-SCH and the first synchronizer. The seventh multiplier 121 multiplies and outputs the channel gain control signal Gp and multiplies the second synchronous channel signal S-SCH by the second synchronous channel gain control signal Gs.

The second accumulator 123 accumulates and outputs each channel signal of the fifth, sixth, and seventh multipliers 117, 119, and 121 in predetermined slot units.

The split real & complex part 125 separates the accumulated channel signal into a real part Re {T} and an imaginary part Im {T}, and outputs the baseband filter 127,129. ) Filters the baseband signal among the signals separated from the real / complex number separating unit 125. The eighth multipliers 131 and 133 multiply the outputs of the corresponding baseband filters 127 and 129 by the corresponding carriers (cos (wt) and -sin (wt)), respectively, and the second adder 135 outputs the two signals. It is multiplied and sent to the receiver.

2, the operation of the W-CDMA receiver is as follows.

The signal received from the RF module of the mobile station proceeds to the process of distinguishing slot synchronization in the first step, frame synchronization in the second step, and scrambling code identification in the third step. do.

The slot synchronizer 210 captures a signal for a synchronization channel using a P-SCH matched filter 211. The signal filtered by the matched filter 211 is accumulated by a certain number of slots in the accumulator 213, and the peak detector 215 selects a maximum value having the highest peak value during slot timing among the accumulated results to obtain a slot synchronization signal. . The slot synchronization signal is input again to the frame synchronization unit 215.

The frame synchronizer 215 correlates the second synchronization channel in parallel by using 16 correlators at the starting point of each slot by the slot synchronization signal using 16 correlators (S-SCH correalators) 221a to 221n. Take Sixteen outputs at the beginning of each slot are stored in the correlator bank 16 * 15. In this case, the cyclic shift of all group codes is considered by the cyclic shift of code group code 223 at the start of each frame using the 64RS code used to distinguish the scrambling code group. This adds the value of the correlator bank for one frame, resulting in 960 decision variables. The maximum detector 225 then determines a code having the maximum value among the variables determined above during the frame timing among the code group codes as the scrambling group ID and determines the start point of the frame.

The scrambling group ID and the starting point of the frame are input to the scrambling code identification unit 230. The scrambling code identification unit 230 determines the scrambling code through a correlation of a predefined symbol on a common pilot channel input from a symbol by symbol correlation unit 231. At this time, each scrambling code group ID includes eight scrambling codes.

If all of the above procedures are successfully performed, then the control channel is received to obtain the information of the base station.

3 is a diagram illustrating a synchronization channel structure of a conventional W-CDMA.

3, (a) is a primary synchronization code (Primary synchronization code), (b) is a second synchronization channel (SSCik: Secondary synchronization code), (c) is a common pilot channel (Common pilot code). One frame is composed of 15 slots, and the first synchronization channel and the second synchronization channel are transmitted by the length of N1 chip (256 chips) at the beginning of every slot, and are overlapped with each other because the orthogonality between the two channels is maintained. . The common pilot channel is composed of downlink scrambling codes so that different PN codes are used for each base station, and the period of the PN code is equal to the length of one frame.

In the base station transmitter, the first synchronous channel (P-SCH) transmits a first synchronous code having the same 256 chip length to all base stations at the beginning of each slot, and the second synchronous channel (S-SCH) has 64 types of reads. Solomon (RS (15,3)) codes are used to transmit for 256 chips at the beginning of each slot. The common pilot channel (CPICH) transmits a scrambling code used to distinguish a base station through a predefined symbol.

However, the cell search technique of the existing W-CDMA system has a long cell search time by using 512 different scrambling codes to distinguish base stations, and increases cell complexity by using 16 correlators in step 2. By using two synchronization channels, the power of the base station is wasted. In addition, there is a problem that the basic duty time becomes longer by performing three steps.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In the forward link, code division multiplexing is performed to transmit code group information and frame start information by polarly modulating at least one synchronization channel among two different synchronization channels in a forward link. It is an object of the present invention to provide a synchronization word transmission and reception method using a polarization modulation and an apparatus thereof in an access communication system.

One feature of the present invention is to transmit the polarization modulation to the first sync code of 256 chip length transmitted at the beginning of each slot to the first sync channel, the second sync channel and the common pilot channel transmitted for compatibility with the existing system The base station and the base station through the mobile station receiving means for performing energy detection using the output of the matched filter on the first synchronous channel receiving the transmission signal of the base station transmitting means and performing a three-stage cell search operation. An object of the present invention is to provide a synchronization word transmission and reception method using a polarization modulation and a receiving device in a code division multiple access communication system capable of obtaining synchronization.

Another feature of the present invention is a synchronization word using polarity modulation in a code division multiple access communication system in which only one code is selected from the 16 second synchronous codes and the polarity is modulated to transmit code group information and frame start information. Its purpose is to provide a transmission and reception method and a reception apparatus.

A further aspect of the present invention is to provide a sync word transmission and reception method using a polarization modulation and a receiving apparatus in a code division multiple access communication system which proposes a new code having a polarization modulated 64 kinds and 15 lengths to distinguish a code group. There is a purpose.

1 is a block diagram showing a configuration of a conventional W-CDMA transmitter.

2 is a block diagram showing the configuration of a conventional W-CDMA receiver.

3 is a diagram illustrating a structure of a conventional W-CDMA synchronization channel.

4 is a diagram illustrating a configuration of a W-CDMA transmitter according to an exemplary embodiment of the present invention.

5 is a diagram illustrating a configuration of a W-CDMA receiver according to an exemplary embodiment of the present invention.

6 is a diagram illustrating a structure of a W-CDMA synchronization channel according to an embodiment of the present invention.

7 is a block diagram illustrating a polarity code generator according to an exemplary embodiment of the present invention.

8 is a view showing a first step cell search procedure according to an embodiment of the present invention.

9 is a view illustrating a second step cell search procedure according to an embodiment of the present invention.

10A and 10B illustrate scrambling group codes applied to an embodiment of the present invention.

11 illustrates a structure of a W-CDMA synchronization channel according to another embodiment of the present invention.

<Explanation of symbols for the main parts of the drawings>

301 ... Serial and Parallel Conversion Unit

303,305,307,317,319,321,331,333 ... multipliers

309,335 ... Adder 311,313 ... Gain Adjuster

315,323 ... accumulator 325 ... real / complex

327,329 ... baseband filter

Slot synchronization unit 411 Matching filter

413 Accumulator 415 Memory

417 Peak detector 420 Frame synchronizer

421 ... Circulation shift part 423 ... Max value detection part

425 Verification mode section 430 Scrambling code identification section

431 ... Correlator between symbols 350 ... 1st polar code generator

360 ... Second Polar Code Generator 370 ... Exclusive Oagate

In order to achieve the above object, in the code multiple access communication system according to the present invention, a synchronization signal transmission method using polarization modulation,

In a communication system of a code division multiple access method,

Transmitting a first synchronization code of a length corresponding to a predetermined number of chips transmitted at the beginning of every time slot of the first synchronization channel by polarity modulation with a code generated for any purpose;

And transmitting a scrambling code used to distinguish a base station through a predefined symbol on a common channel.

Preferably, the polarity modulated code is equal to the number of scrambling group codes, and the length is a code having a length equal to the number of time slots per one radio frame.

Preferably, the number of scrambling group codes is 64 types, and the number of time slots per one radio frame is 15.

Preferably, the polarity modulated code is a random binary code or gold code or Walsh code having polarity and generated for any purpose.

Preferably, the method may further include transmitting a Reed Solomon code at each time slot start point of a 15-length 16 type second synchronization channel according to system compatibility.

Preferably, the second synchronous channel is characterized in that for transmitting one of the second synchronous code transmitted for 256 chips at the starting point of every time slot by polarity modulation.

In a code division multiple access communication system according to another embodiment of the present invention, a synchronization word reception method using polarization modulation is provided.

A cell search method for synchronization acquisition with a base station in a code division multiple access communication system, comprising: a first step of acquiring time slot synchronization using a matched filter output of a polarized modulated first synchronization channel; A second step of acquiring a radio frame synchronization and a code group recognizer using the output of the time slot synchronization and matching filter obtained in the first step; And identifying a scrambling code through correlation with a common pilot channel using synchronization of a group code recognizer and a radio frame obtained in the second step.

Preferably, the first step includes: accumulating the output of the matched filter for the signal of the polarity-modulated first synchronization channel, and determining a point at which the output is maximum as a start point of the slot; Storing the output of the matched filter for each sample time of the frame in a memory; And providing the slot time and the outputs of the matched filter as parameters of the second stage.

Preferably, the second step includes performing vector multiplication with the outputs of the matched filter stored in the memory of the slot starting point using 64 predefined scrambling group codes to obtain frame synchronization and group code recognizer; Determining a group code recognizer by obtaining 960 outputs by a cyclic shift of a code group code as a result of the vector multiplication, and selecting a code which is the maximum among them; And moving the circular movement of the selected code to find the starting point of the frame.

In a code division multiple access communication system according to another embodiment of the present invention, an apparatus for receiving a synchronization word using polarity modulation is provided.

A cell search apparatus for synchronization acquisition with a base station in a code division multiple access communication system, comprising: acquiring slot synchronization using a matched filter from a first sync channel signal received from an RF module and storing an output of the matched filter Slot synchronization means for providing post slot timing and matched filter output; Frame synchronization means for obtaining frame synchronization and group code recognizer using the slot timing and matched filter output; Means for identifying a scrambling code using the frame sync and group code identifier.

Preferably, the slot synchronizing means includes a matching filter, an accumulator for accumulating the output of the matching filter by a predetermined slot, a memory for storing the output of the matching filter at each sample time, and a value accumulated in the predetermined slot unit. Characterized in that it comprises a value as a peak detector to determine the starting point of the slot,

The frame synchronizing means includes a cyclic shift unit for cyclically shifting code group codes, a maximum value detector for detecting a maximum value of the code group code during frame timing among the cyclically shifted values, and stored in the memory for all selected candidates. After multiplying the output of the matched filter by vector, the outputs of one candidate are summed and stored as decision variables. After calculating decision variables for each candidate, the candidate with the maximum value is selected as the code group recognizer. And verify mode means for determining the starting point of the frame.

Hereinafter, with reference to the accompanying drawings as follows.

4 is a configuration diagram of a W-CDMA transmitter according to an embodiment of the present invention, FIG. 5 is a configuration diagram of a W-CDMA receiver according to an embodiment of the present invention, and FIG. 6 is a W-CDMA synchronization channel according to an embodiment of the present invention. A diagram showing the structure of the.

4, a serial-to-parallel converter 301 for converting received common pilot channel signals in parallel to I-channel and Q-channel data; First and second multipliers (303, 305) for spreading common pilot data separated into respective I and Q channels using a channel spread code (Cch, SF, m); A third multiplier 307 for phase shifting the spread data of the Q channel by 90 degrees; A first adder 309 that adds the outputs of the first multiplier 303 and the third multiplier 307 to generate a complex spread addition signal I + jQ; Gain adjusters 311 and 313 for multiplying the complex diffusion signal of each channel by different gain control signals G1, ..., G2; A first accumulator 315 for accumulating and outputting channel signals whose gains are adjusted by the gain controllers 311 and 313, and a fourth multiplier 317 for multiplying the output of the accumulated channel signals by the scrambling code signals Sdl and n; A polarity modulator 318 for polarizing the polarity using a polarity code on the first synchronization channel, and a fifth multiplier 319 for multiplying the polarity-modulated first synchronization channel by the channel gain signal; A sixth multiplier 321 for multiplying the second synchronous channel with a channel gain control signal, a second accumulator 323 for accumulating a synchronization channel and a common pilot channel signal, and a real number for dividing the accumulated channel signal into a real signal and a complex signal / Complex separator 325, baseband filters 327, 329, seventh and eighth multipliers 331, 333, and second adder 339.

Referring to FIG. 5, a matching filter 411 for matching filtering the polarity-modulated first synchronization channel, an accumulator 413 accumulating the output of the matching filter for a predetermined slot, and a memory storing the output of the matching filter in units of frames. A slot synchronizer 410 including a peak detector 417 for detecting a maximum value of an output value of the matched filter;

A cyclic shift unit 421 for cyclically shifting a predefined scrambling code group code, and a maximum value detector 423 for selecting a maximum value candidate by vector multiplication using a scrambling code group code, an output of the matched filter, and a slot start point. And a verification mode unit 425 which cyclically shifts the candidate selected from the maximum value detector and performs a vector multiplication with the output value of the matched filter to select a code having the maximum value to obtain a scrambling group ID and frame start information. A synchronization unit 420;

And a scrambling code identification unit 430 including an inter-symbol correlation unit 431 for identifying a scrambling code through correlation with a common pilot channel using the scrambling code ID and frame start information through the inter-symbol correlation. to be.

Referring to the accompanying drawings, a sync word transmission and reception method using polarization modulation and a device in a code division multiple access communication system according to the present invention are as follows.

4 is a configuration diagram illustrating a synchronization word transmitter according to an embodiment as a configuration diagram of a W-CDMA transmitter.

Referring to FIG. 4, the serial-to-parallel converter 301 converts the received signals of the common pilot channel in parallel to I-channel and Q-channel data. The first and second multipliers 303 and 305 spread common pilot data separated into respective I and Q channels using channel spread codes Cch, SF and m. The third multiplier (or phase shifter) 307 phase shifts the spread data of the Q channel by 90 degrees. The first adder 309 adds the outputs of the first multiplier 303 and the third multiplier 307 to generate a complex spread add signal I + jQ.

The gain adjusters 311 and 313 multiply the addition signals by the different gain control signals G1, ..., G2, respectively, where the gain control signals G1, ..., G2 are used for the signals transmitted through each channel. This signal controls transmission power control and channel interruption.

The first accumulator 315 accumulates and outputs channel signals whose gains are adjusted by the gain controllers 311 and 313. The fifth multiplier 317 multiplies the output of the first accumulator 315 by the scrambling code signal Sdl, n.

In addition, the polarity modulator 318 uses polarity modulation for the first synchronization channel, and the polarity modulation is applied only to a primary synchronization code (PSC) having a length of 256 chips transmitted at the beginning of each slot. In this case, lengths of codes used for polarity modulation are equal to the number of slots per frame. Codes that can be used may be codes generated for any purpose, such as polarized random binary code and Gold code, or Walsh code. Here, the applied gold code represents a scrambling code group like the Reed Solomon code in the existing W-CDMA.

The first synchronization channel P-SCH polarized by the polarity modulator 318 multiplies the first synchronization channel gain control signal GP and outputs the multiplied first synchronization channel gain control signal GP. The second accumulator 323 accumulates and outputs the output of the fifth multiplier 317 and the output of the sixth multiplier 319.

In this case, the channels (S-SCH, CPICH) and data channels used for cell search are transmitted without change for compatibility with the existing system. Therefore, only polarity modulation is applied to the first synchronization channel of standard W-CDMA. Therefore, the seventh multiplier 321 multiplies the second synchronization channel gain control signal GS by the second synchronization channel and outputs the same to the second accumulator 323 for compatibility with the existing system.

On the other hand, the output of the second accumulator 323 is separated from the real / complex number separating unit 325 and the baseband filters (Pulse shaping) (327,329) respectively to filter the baseband signal. The eighth and ninth multipliers 331 and 333 multiply the outputs of the corresponding baseband filters 327 and 329 by the corresponding carriers (cos (wt) and -sin (wt)), respectively. The adder 335 adds the channel signal multiplied by the corresponding carrier and transmits the signal to the receiver.

As an example, as shown in FIG. 6, FIG. 6A illustrates a polarity-modulated first synchronization channel, wherein the first synchronization code PSC transmitted at the beginning of each slot is 64 kinds of 15 lengths previously defined. It is transmitted by performing polarization modulation using a Gold code having a gi (Gi: Gold Code for Polarization Modulation (length 15, i = {1, 2, ..., 64)). That is, polarization modulation is only applied to the first 256-bit long sync code transmitted at the beginning of every slot. In this case, the lengths of the codes used for polarity modulation are equal to the number of slots per frame. 6B illustrates a common pilot channel.

5 shows the configuration of a mobile station receiver. The mobile station receiver has the receiving end structure used in the W-CDMA standard and can receive a signal transmitted from a base station. That is, the polarity modulated first synchronization channel can be received because energy detection using the output of the matched filter for the first synchronization channel is performed.

The slot synchronizer 410 captures a signal for a polarity-modulated first synchronization channel from a signal input through an RF module in a P-SCH matched filter 411. An accumulator 413 accumulates the output of the matching filter 411 for a predetermined slot, and the output of the matching filter 411 is stored in the memory 415 at each sample time, that is, in units of frames. . The peak detector 417 determines a point at which the output becomes the maximum among the output values accumulated by the accumulator 413 during the slot timing as the start point of the slot and outputs it as the slot synchronization signal.

T1: Number of slots accumulated in step 1

u: The position where slot starting point can exist, 0≤ u ≤2559

T: one slot length, T = 2560 chips

y _j : received complex baseband samples

τ1: threshold for P-SCH

The frame synchronizer 420 does not receive a signal from the base station, but acquires the frame synchronization and the code group ID by using the slot time obtained by the slot synchronizer 410 and the output of the matching filter 411.

In this case, vector multiplication is performed with the outputs of the matched filter 411 stored in the memory 415 of the slot starting point using a predefined gold code, that is, 64 scrambling group codes. As a result, a total of 960 outputs can be obtained considering the cyclic shift of the code group codes. Then, the maximum value detector 417 selects a code that becomes the maximum during the frame timing from among the code group codes to determine the actual code group ID. Also, the starting point of the frame is found by using the cyclic shift of the selected code.

-------- Equation 2

Yu *: Output of matched filter stored in memory

CPC: Cyclic Shift Polarization Code

T ₂ : Number of slots accumulated in step 2

C: Number of PCs considering cyclic shift (960), C = n * G, n = length of PC (15)

In addition, the verification mode unit 425 searches for a code that becomes the maximum among the L candidates having selected L candidates from the maximum value. That is, in the verify mode, all selected candidates are cyclically shifted, and then vector multiplication is performed with the output value of the matched filter obtained in the first step. This is to use cyclic shifts to match the phase of the code and to improve cross correlation. After that, all vector operation values are added and used as decision variables. Finally, the code having the maximum value among the decision variables is selected to obtain the scrambling code group ID and the start information of the frame.

That is, since the code group code is a kind of gold code, the cross correlation property between the cyclically shifted codes is good. Therefore, vector multiplication is performed between codes considering all cyclic shifts at the frame start point of each candidate and the output of the matched filter stored in the memory in the first step. Then we add the outputs for one candidate and store them as decision variables.

After calculating the decision variables for each candidate, all the decision variables are compared. Among them, the candidates having the maximum value are selected as the code group ID and the start point of the corresponding frame is determined. The above process may be represented by Equation 3 below.

----- Equation 3

Yu *: Output of matched filter stored in memory

CPC: Cyclic Shift Polarization Code

L: posterior number selected in Pre-Detection Mode, L = n (m), m ∈ {1,2,.. .., C}

n (X): number of elements in set X

m: Candidates selected in Pre-Detection Mode during CPC

Trace: Sum of the diagonal elements of an N * N matrix, Tr (X)

Thereafter, the inter-symbol correlation unit 431 of the scrambling code identification unit 430 of the third step uses the code group ID determined in the second step and the start point of the frame, as in the existing W-CDMA system, through correlation with the CPICH. By identifying the scrambling code, the base station is identified. The process is as shown in Equation 4.

------------ Equation 4

T3: Number of slots accumulated in step 3

f: starting point in the frame selected in step 2, 0≤f≤38399

S: symbol duration, S = 256 chips

d: cumulative number of symbols, d = T3 * 10

y _j : received complex baseband samples

G: number of scrambling group codes, G = 64

w: number of scrambling codes per group, W = number of scrambling codes / G = 8

The above-described receiver for searching for a cell is considered to be compatible with the existing W-CDMA, and if a base station transmits a polarity-modulated first synchronization channel (P-SCH) and a second synchronization channel (S-SCH) within a base station, A terminal of W-CDMA and a terminal proposed by the present invention may exist simultaneously.

That is, in FIG. 4, the multiplier 321 multiplying the second synchronous channel and the second synchronous channel gain control signal is left as it is, thereby polarizing and transmitting the first synchronous channel and transmitting the second synchronous channel as before. By transmitting, a terminal of the W-CDMA and a terminal proposed by the present invention can exist simultaneously in one base station.

In addition, by receiving only the base station signals of the first and third stages, the cell search period is shortened and the existing 16 correlators can be removed.

FIG. 7 is a polarity code generator according to an embodiment of the present invention, and is generated using two linear feedback shift registers (LFSRs) having six consecutive shift registers.

Referring to FIG. 7, a polar code is generated by an exclusive sum of two different sequences. The shift registers 351 to 356 of the upper first polar code generator 350 have a generation polynomial f (x) = x6 + x1 + 1, and the shift registers 361 to 366 of the lower second polar code generator 360. Is implemented with f (x) = x6 + x5 + x4 + x1 + 1.

In addition, the initial values of the six shift registers 351 to 356 configured on the upper side are set to 1,0,0,0,0,0 in order from the first to the sixth order, and the first shift register 351 The output of the second shift register 352 is exclusively summed by the exclusive oragate 357 and sequentially input to the sixth shift register 356.

The initial values of the six shift registers 361 to 366 configured at the lower side are all 1s, and the output of the first shift register 361 and the output of the second shift register 362 form the first exclusive orifice 367. Is outputted through the second exclusive ogate 368, and the output of the second exclusive ogate 368 is exclusively calculated with the output of the fifth shift register 365, and the third exclusive ogate 369 is configured to be the second. The output of the exclusive ogate 368 and the output of the sixth shift register 366 are exclusively summed and input to the sixth shift register 366.

The exclusive output operation of the first shift register 351 of the first polarity generator 350 and the output of the first shift register 361 of the second polarity generator 360 are performed by an exclusive oragate 370. And output. At this time, the output of the exclusive oragate 370 is output as 1 and 0, so that the polarity code consisting of 1 and -1 can be generated by setting 1 to -1 and 0 to 1 for application to a code for polarity modulation. have.

This polar code generator can be used to generate gold codes having 63 lengths of 64. However, the actual code used is a code that has 15 consecutive lengths in each gold code and has a good cross correlation. This can generate 64 codes, such as FIGS. 10A and 10B. That is, the polarity code is a code of a length of 15 among gold codes generated by using two six-speed shift registers. The type is 64 equal to the number of scrambling group codes and the length is 15 equal to the number of slots per frame. Thus, the polarity code performs polarity modulation on the same PSC transmitted at every slot time.

8 illustrates a one-step cell search procedure according to an embodiment of the present invention.

The mobile stations use matching filters 441: 441a-441c to obtain slot synchronization for signals transmitted from the base station, and the outputs of each of the matching filters 441a-441c are memory 446 and a multiplier 442a-. 442c). In this case, the output value of the matched filter having the polarity information is stored in the memory 446 and stored in the unit of a sample equal to one frame length. The power supplies 442a to 442c obtain the power of the received signal from the output of the matched filter, respectively, and add them to the adders 443a to 443c. Therefore, the combiners 444a to 444b accumulate for each slot time for one frame length.

Therefore, the total decision variable can obtain 2560 chips of one slot. The maximum value detector detects the maximum value of the 2560 decision variables and provides the slot timing information to the memory. Thus, the maximum value detector detects the starting point information of the slot and one frame length corresponding to the starting point of each slot, that is, samples for 15 slots. Transfer for step cell search procedure.

9 illustrates a proposed two-step cell search procedure. In step 2, vector multiplication is performed to obtain a group ID and start information of a frame. This vector multiplication is divided into two modes, a predetection mode 510 and a verification mode 520.

The predetermined mode 510 uses scrambling group codes Gc1 to Gc64 having polarity information and an output value 511 of the matched filter in the first step.

In order to obtain the start information of the frame using the cyclic shift of each scrambling group code, 15 cyclic shift codes are generated for each group code and vector multiplication is performed. Therefore, 960 (15 slots * 64 (group codes)) can be obtained as a decision variable at this time. That is, 960 decision variables are obtained by performing vector multiplication of the output 511 of the matched filter and each of 15 generated in the group codes Gc1 to Gc64.

Then, the verification mode 520 is performed by selecting as many candidate numbers L as previously defined from the largest value among the 960 decision variables. In the verification mode 520, the output value of the matched filter obtained in step 1 of the cyclic shift (Gc1 to GcL) is performed on all candidates selected in the predetermined mode 510, respectively.

The reason for doing this is to improve the cross correlation property using cyclic movement. Then all vector operation values are added (523,525) to use as decision variables. Finally, the code having the maximum value among the decision variables is selected to obtain the scrambling code group ID and the start information of the frame.

Meanwhile, another embodiment of the present invention will be described with reference to FIG. 11. In the description of another embodiment, a redundant description and duplicated components will be briefly described.

The base station transmitter selects one code among the existing 16 second synchronization channel codes and uses polarity modulation. To this end, in the base station transmitter shown in FIG. 4, the polarity modulator 318 may be configured to perform polarity modulation by using a polarity code on the second synchronization channel S-SCH in front of the seventh multiplier 321. .

Therefore, one second synchronization channel transmitted at the beginning of each slot is transmitted by polarity modulation using a predefined gold code having 64 kinds of 15 lengths. At this time, the gold code indicates a scrambling code group like the RS code in the existing W-CDMA. Therefore, the first synchronization channel and the polarity-modulated second synchronization channel are transmitted at the same power. The scrambling code of the base station is transmitted through the CPICH to determine the scrambling code.

Referring to FIG. 11, a common pilot channel is defined in a first synchronization channel and a second synchronization channel in a forward link. The sync channel is 256 chips long at the beginning of 15 slots in a 10 ms frame. The type of scrambling code for identifying the entire base station is 512, and the length is 38400 chips long. Therefore, the overall structure has a structure of a synchronization channel and one pilot channel. As in 3GPP, the first synchronous channel uses a common code having a length of 256 chips commonly used by all base stations.

In the second synchronous channel, one of 16 second synchronous codes defined in 3GPP is selected and transmitted by 256 chips in length at the start of every slot. At this time, the polarity modulation is transmitted to each second synchronization code by using the polarity code defined to distinguish the scrambling group code. That is, one second synchronization code transmitted at the start of each slot is modulated and transmitted using a gold code having 64 kinds of 15 predefined lengths. At this time, the gold code indicates a scrambling code group like the RS code in the existing W-CDMA. Therefore, it is transmitted at the same power as the second synchronization channel polarized with the first synchronization channel. The scrambling code of the base station is transmitted through the CPICH to determine the scrambling code.

In this case, the polarity code is a code having a length of 15 among the gold codes generated by using two six-stage shift registers as shown in FIG. 7. The type is 64 equal to the number of scrambling group codes, and the length is 15 equal to the number of slots per frame. Thus, the polarity code performs polarization modulation on the same second sync code transmitted at every slot time.

The cell search operation in the mobile station receiving the two synchronization channels and the CPICH including the polarity-modulated second synchronization channel in the base station as follows.

Basically, it is composed of 3 steps, similar to the 3GPP cell search scheme, and the base station is distinguished by performing the actual 3 steps. The first step for obtaining synchronization with the base station is accumulated for several slots for the matched filter of the first synchronous channel, so as to identify the boundary of the slot by selecting a point where the output is maximum. The slot timing obtained as a result of the first step is used as a parameter of the second step.

The second step is to identify frame synchronization and scrambling group IDs. Using the slot time obtained in the first step, an output having the polarity information is obtained through a single correlator with the second synchronization code defined at every slot start point. This process can be defined by Equation 5.

The vector multiplication is performed using 64 outputs of the correlator thus obtained and 64 predefined scrambling group codes as shown in FIGS. 10A and 10B. As a result, the cyclic shift of the code group code is considered. You get a total of 960 outputs. This process can be defined as in Equation 6.

Thereafter, the maximum code among the 960 outputs is selected to be selected as a code group ID candidate. The starting point of the frame is found by the cyclic shift information of the selected code. Multiple candidates can be selected from 960 vector multiplications to improve system performance.

Next, the verification procedure for the selected candidates is performed. Because code group codes are a type of gold code, they have good cross correlation between cyclically shifted codes. Accordingly, vector multiplication is performed between the correlator output and the scrambling group code at the positions of the codes considering all the cyclic shifts by considering the frame starting point of each candidate.

This gives 15 outputs for one candidate. Finally, the 15 outputs for each candidate are summed as Equation 7 and designated as decision variables. After calculating the decision variables for each candidate, all the decision variables are compared. The candidates having the maximum value are selected as the code group IDs and the start point of the corresponding frame is determined.

Equation 5

--------- Equation 6

--------- Equation 7

Y _j : Received signal at the start of every slot (SSC position)

SSC _j : SSC, j = {0,1, .., 255}

i: slot number (based on slot timing of step 1), i = {1,2, ..., 15}

k: scrambling group code {1,2, ... 64}

CPC _i : Polarity code i = {1,2, ..., 15} taking into account cyclic shift

In other words, in the second step, the frame synchronization and the scrambling code group are identified. Referring to FIG. 9, a second correlator channel defined at every slot start point is obtained through one correlator using the slot time obtained in the first step. Obtain polarity information at its output. The vector multiplication is performed using the output of the correlator thus obtained and a predefined gold code, that is, 64 scrambling group codes. As a result, a total of 960 outputs can be obtained in consideration of the cyclic shift of the code group codes. The maximum code among them is selected to determine the actual code group ID. Also, the starting point of the frame is found by using the cyclic shift of the selected code. Multiple candidates can be selected from the outputs to improve system performance. As a result, the number of selected candidates can be increased to improve the performance of the system. Thereafter, a verification procedure is performed on the selected candidates. Here, the code group code is a kind of gold code, and thus has a good cross correlation property between cyclically shifted codes. Therefore, at the start of the frame of each candidate, the codes considering all the cyclic shifts and the second correlator output are vector multiplied.

Then we add the outputs for one candidate and store them as decision variables. In this way, the decision variables are calculated for each candidate and all the decision variables are compared. The candidates having the maximum value are selected as the code group IDs and the start point of the corresponding frame is determined.

Thereafter, the third step is to perform the cell search in the same manner as the existing W-CDMA system. In the third step, the actual scrambling code is obtained. The scrambling code is identified through correlation with CPICH using the code group ID determined in step 2 and the starting point of the frame.

On the transmitting side, the polarity modulation is added to the transmission structure of the existing P-SCH so that the base station performs polarity modulation on the P-SCH. In addition, the receiver may receive cell search related information using polarity information of the received signal. Therefore, in the first step, the start information of the frame and the scrambling code group ID are identified by vector multiplication using the newly defined scrambling code group code using the output of the matched filter.

As described above, according to the method and apparatus for transmitting and receiving a sync word in a code division multiple access communication system according to the present invention, a base station transmits a specific sync channel using polar modulation and the mobile station is polarly modulated with respect to the same. By acquiring synchronization through the search of the synchronization word, a cell search time is shorter than that of the conventional W-CDMA scheme in all wireless signal environments, and a cell drop time is reduced in a bad signal environment, thereby causing a call drop during handoff of a mobile station. ) Has the advantage of reducing the probability.

In addition, since the signal is received only in the first and third stages of the three-stage cell search in a good environment, the cell search period can be reduced.

In addition, the complexity of the receiver can be reduced by eliminating the 16 correlators used in the second step when searching for existing cells, reducing the overall system throughput by more than 60%, increasing the received signal gain by 3dB, and interfering with synchronization channels. This has the advantage of shrinking.

In addition, the gain of the signal can be obtained at the base station by using only one existing second synchronization code, and the performance of the W-CDMA system is improved by reducing the cell search time and the complexity of the receiver through cell search using polarity modulation. It can give an effect.

Claims (12)

In a communication system of a code division multiple access method, Transmitting a first synchronization code of a length corresponding to a predetermined number of chips transmitted at the beginning of every time slot of the first synchronization channel by polarity modulation with a code generated for any purpose; And transmitting a scrambling code used to distinguish a base station through a predefined symbol through a common channel. The method of claim 1, The polarity modulated code is equal to the number of scrambling group codes, the length is a code having a length equal to the number of time slots per one radio frame, characterized in that the synchronization word transmission method using polarization modulation in a code division multiple access communication system. The method of claim 2, The number of the scrambling group code is a predefined 64 kinds, the number of time slots per one radio frame is 15. The sync word transmission method using polarization modulation in a code division multiple access communication system. The method of claim 1, The polarity modulated code is a random binary code or a gold code or a Walsh code having a polarity and generated for an arbitrary purpose. The synchronization word transmission method using polarity modulation in a code division multiple access communication system. The method of claim 1, And selectively transmitting a Reed Solomon code at each time slot start point of a 15-length 16-type second synchronous channel according to system compatibility in transmitting the sync word. Synchronization word transmission method using modulation. The method of claim 5, In the code division multiple access communication system, the second synchronization channel selects one code among the second synchronization codes transmitted for 256 chips at a reference point of each time slot, and transmits the code by polarity modulation. Synchronization word transmission method. A cell search method for synchronization acquisition with a base station in a code division multiple access communication system, A first step of acquiring time slot synchronization using a matched filter output of the polarity-modulated first synchronization channel; A second step of acquiring a radio frame synchronization and a code group recognizer using the output of the time slot synchronization and matching filter obtained in the first step; And identifying a scrambling code through correlation with a common pilot channel using synchronization of a group code recognizer and a radio frame obtained in the second step. Synchronization word reception method using. The method of claim 7, wherein The first step includes accumulating the output of the matched filter for the signal of the polarity-modulated first synchronization channel, and determining a point at which the output becomes the maximum as the start point of the slot; Storing the output of the matched filter for each sample time of the frame in a memory; And providing the slot time and the outputs of the matched filter as parameters of the second step. The method of claim 7, wherein The second step includes performing vector multiplication with the outputs of the matched filter stored in the memory of the slot starting point using 64 predefined scrambling group codes to obtain frame synchronization and group code recognizer; Determining a group code recognizer by obtaining 960 outputs by a cyclic shift of a code group code as a result of the vector multiplication, and selecting a code which is the maximum among them; And moving the cyclic movement of the selected code to find the starting point of the frame. A cell search apparatus for synchronization acquisition with a base station in a code division multiple access communication system, Slot synchronizing means for acquiring slot synchronization using a matched filter from a first synchronization channel signal received from the RF module, storing the output of the matched filter, and providing slot timing and matched filter output; Frame synchronization means for obtaining frame synchronization and group code recognizer using the slot timing and matched filter output; And a means for identifying a scrambling code using the frame synchronization and group code recognizer. The method of claim 10, The slot synchronizing means includes a matching filter, an accumulator for accumulating the output of the matching filter by a predetermined slot, a memory for storing the output of the matching filter at each sample time, and a value that is the maximum value of the accumulated value in the predetermined slot unit. Characterized in that it comprises a peak detector to determine the starting point of, The frame synchronizing means includes a cyclic shift unit for cyclically shifting code group codes, a maximum value detector for detecting a maximum value of the code group code during frame timing among the cyclically shifted values, and stored in the memory for all selected candidates. After multiplying the output of the matched filter by vector, the outputs of one candidate are summed and stored as decision variables. After calculating the decision variables for each candidate, the candidate with the maximum value is selected as the code group ID. And a verification mode means for determining a start point of a frame. The method of claim 10, The communication system is a synchronization word receiving apparatus using polarity modulation in a code division multiple access system, characterized in that the mobile communication terminal.