RU2434330C2 - Method of performing cell search in wireless communication system - Google Patents

Abstract

FIELD: information technology.

SUBSTANCE: method of performing cell search involves receiving a primary synchronisation signal (PSS) containing a primary synchronisation code (PSC) and receiving a secondary synchronisation signal (SSS) containing a first secondary synchronisation code (SSC) and a second SSC. The first SSC and the second SSC are respectively scrambled using a first scrambling code and a second scrambling code, and the first scrambling code and the second scrambling code are linked to the PSC. The quality of detecting synchronisation signals can be enhanced and cell search can be performed more reliably.

EFFECT: high reliability of cell search.

15 cl, 19 dwg

Description

Technical field

[1] The present invention relates to wireless communication systems and, in particular, to a method for performing a cell search in a wireless communication system.

State of the art

[2] Wide code division multiple access (WCDMA) systems of the 3rd generation partnership project (3GPP) use a total of 512 long pseudo-noise (PN) scrambling codes to identify the base stations (base stations, BS). As a downlink scrambling code, each base station (BS) uses a different long pseudo noise (PN) scrambling code.

[3] When power is supplied to the user equipment (UE), the user equipment (UE) synchronizes the cell in the downstream direction and acquires the identifier (ID) of the long pseudo noise (PN) scrambling code of the cell. Such a process is commonly called cell search. Cell search is the procedure by which a user equipment (UE) acquires time and frequency synchronization with a cell and determines the identity of the cell. The start cell is determined according to the location of the user equipment (UE) at a time when power is being supplied. Typically, the start cell indicates a base station (BS) cell corresponding to the largest one of the signal components of all base stations (BS) that are included in the downstream signal received by the user equipment (UE).

[4] To perform a cell search, the WCDMA system divides 512 long pseudo noise (PN) scrambling codes into 64 code groups, and uses a downstream channel, including a primary synchronization channel (P-SCH) and a secondary synchronization channel, S-SCH). The primary synchronization channel (P-SCH) is used to obtain slot synchronization by the user equipment (UE). The secondary synchronization channel (S-SCH) is used to obtain frame synchronization and a scrambling code group by the user equipment (UE).

[5] Typically, a cell search is classified into an initial cell search, which is initially performed when the user equipment (UE) is turned on, and an initial search that performs a handover or measurement of a neighboring cell.

[6] In the WCDMA system, cell search is carried out in three stages. In a first step, a user equipment (UE) receives slot synchronization using a primary synchronization channel (P-SCH), including a primary synchronization code (primary synchronization with ode, PSC). A frame includes 15 slots, and each base station (BS) transmits a frame by including a primary synchronization code PSC. Here, the same primary synchronization code (PSC) is used for 15 slots, and all base stations (BS) use the same primary synchronization code (PSC). The user equipment (UE) receives slot synchronization using a matched filter suitable for the primary PSC synchronization code. In a second step, a long pseudo noise (PN) scrambling code group and frame synchronization are received using slot synchronization and also using a secondary synchronization channel (S-SCH), including a secondary synchronization code (SSC). In a third step, using a common pilot channel code correlator based on frame synchronization and a long pseudo noise (PN) scrambling code group, the user equipment (UE) determines a long pseudo noise (PN) scrambling code identifier (ID) corresponding to a long pseudo noise (PN) scrambling code used by the start cell. That is, since 8 long pseudo noise (PN) scrambling codes are mapped to a single scrambling code group of long pseudo noise (PN) codes, the user equipment (UE) calculates the correlation values of all 8 long pseudo noise (PN) scrambling codes belonging to the user equipment (UE) code group ) Based on the result of the calculation, the user equipment (UE) determines the identifier (ID) of the long pseudo noise (PN) scrambling code of the initial cell.

[7] Since the WCDMA system is an asynchronous system, only one primary synchronization code (PSC) is used in the primary synchronization channel (P-SCH). However, given that next-generation wireless communication systems must support both synchronous and asynchronous modes, multiple primary synchronization codes (PSCs) must be used.

[8] If an error occurs during the determination of the secondary synchronization channel (S-SCH), a delay occurs when the user equipment (UE) performs a cell search. Therefore, there is a need to improve channel determination characteristics in a cell search procedure.

Disclosure of invention

Technical problem

[9] A method for improving the determination characteristics is sought by performing scrambling such that various scrambling codes are used for the secondary synchronization signal (SSS).

[10] A method is also being sought for performing reliable cell searches by improving the detection characteristics of a secondary synchronization signal (SSS).

[11] A method is also being sought for transmitting synchronization signals by improving the detection characteristics of the synchronization signals.

Technical solution

[12] In one aspect, a method for performing a cell search in a wireless communication system is provided. The said method includes receiving a primary synchronization signal (PSS) containing a primary synchronization code (PSC) acquiring a unique identifier from a primary synchronization signal (PSS), receiving a secondary synchronization signal (SSS), which is associated with a cell identification group, a secondary synchronization signal SSS, comprising a first secondary synchronization code (SSC) and a second secondary synchronization code (SSC), and acquiring a cell identifier that is determined a unique identifier in the cell identification group, wherein the first secondary synchronization code (SSC) and the second secondary synchronization code (SSC) are respectively scrambled using the first scrambling code and the second scrambling code, and the first scrambling code and the second scrambling code are associated with the primary synchronization code (PSC )

[13] The first secondary synchronization code (SSC) and the second secondary synchronization code (SSC) can be determined by two different cyclic shifts of the m-sequence generated by the generating polynomial x ⁵ + x ² +1. The first scrambling code and the second scrambling code can be determined by two different cyclic shifts of the t-sequence generated by the generating polynomial x ⁵ + x ² +1. The cyclic shifts for the first scrambling code and the second scrambling code may depend on the unique identifier from the primary synchronization code (PSC).

[14] In another aspect, a method for transmitting synchronization signals in a wireless communication system is provided. The method includes transmitting a primary synchronization signal (PSS) containing a primary synchronization code (PSC), and transmitting a first secondary synchronization signal (SSS) containing a first secondary synchronization code (SSC) and a second secondary synchronization code (SSC), wherein the first secondary code synchronization (SSC) are scrambled using the first scrambling code, and the second secondary synchronization code (SSC) is scrambled using the second scrambling code, the first scrambling code and the second scrambling code anes with the primary synchronization code (PSC).

[15] In yet another aspect, a method for obtaining synchronization signals in a wireless communication system is provided. Said method includes identifying a primary synchronization code (PSC) with a primary synchronization signal (PSS) transmitted from a base station, and identifying a first secondary synchronization code (SSC) and a second secondary synchronization code (SSC) with a secondary synchronization signal (SSS) transmitted from said base stations, the first code with secondary synchronization (SSC) and the second code with secondary synchronization (SSC), respectively, are scrambled using the first scrambling code and the second scrambling code, and the first scramble ruyuschy code and the second scrambling code associated with a primary synchronization code (PSC).

Useful result

[16] Cell search can be performed more reliably and delays can be prevented. In addition, with an increase in the number of available sequences, the amount of information transmitted by the synchronization signals and the throughput of the user equipment (UE) can be increased.

Brief Description of the Drawings

[17] Figure 1 shows the structure of a wireless communication system.

[18] FIG. 2 shows an example of a structure of a radio frame.

[19] FIG. 3 shows an example of a physical mapping of two secondary synchronization codes (SSC) to a secondary synchronization signal (SSS).

[20] FIG. 4 shows another example of a physical mapping of two secondary synchronization codes (SSC) to a secondary synchronization signal (SSS).

[21] Figure 5 shows an example of the mapping of two secondary synchronization codes (SSC) to a secondary synchronization signal (SSS).

[22] FIG. 6 shows another example of mapping two secondary synchronization codes (SSC) to a secondary synchronization signal (SSS).

[23] FIG. 7 shows a structure of a secondary synchronization signal (SSS) in accordance with an embodiment of the present invention.

[24] FIG. 8 shows a structure of a secondary synchronization signal (SSS) in accordance with another embodiment of the present invention.

[25] FIG. 9 shows a structure of a secondary synchronization signal (SSS) in accordance with another embodiment of the present invention.

[26] FIG. 10 shows a structure of a secondary synchronization signal (SSS) in accordance with another embodiment of the present invention.

[27] FIG. 11 shows a structure of a secondary synchronization signal (SSS) in accordance with another embodiment of the present invention.

[28] FIG. 12 shows a structure of a secondary synchronization signal (SSS) for a primary synchronization code (PSC) 1.

[29] Fig.13 shows the structure of the secondary synchronization signal (SSS) for the primary synchronization code (PSC) 2.

[30] FIG. 14 shows a secondary synchronization signal (SSS) structure for a primary synchronization code (PSC) 3.

[31] FIG. 15 shows a structure of a secondary synchronization signal (SSS) for a primary synchronization code (PSC) 1.

[32] Fig.16 shows the structure of the secondary synchronization signal (SSS) for the primary synchronization code (PSC) 2.

[33] Fig.17 shows the structure of the secondary synchronization signal (SSS) for the primary synchronization code (PSC) 3.

[34] Fig. 18 is a graph depicting a cumulative distribution function (CDF) of cross-correlation for all possible collisions in two cells.

[35] Fig.19 is a diagram depicting a cell search in accordance with an embodiment of the present invention.

The principle of operation for the invention

[36] Figure 1 depicts the structure of a wireless communication system. A wireless communication system can be widely used to provide various communication services, such as voice, packet data, etc.

[37] Referring to FIG. 1, a wireless communication system includes user equipment 10 (UE) and base station 20 (BS). Said user equipment 10 (UE) may be fixed or mobile, and may be called another term, such as a mobile station (mobile station, MS), a user terminal (user terminal, UT), a subscriber station (subscriber station, SS), wireless device etc. Base station 20 (BS) is usually a fixed station that communicates with user equipment 10 (UE) and may be referred to by another term, such as node-B, base transceiver system (BTS), access point, etc. d. One or more cells may be within the coverage area of the base station 20 (BS).

[38] Said wireless communication system may be a system based on orthogonal frequency division multiplexing (OFDM) / orthogonal frequency division multiple access (OFDMA) technology. OFDM technology uses multiple orthogonal subcarriers. In addition, OFDM technology utilizes the orthogonality between inverse fast Fourier transform (IFFT) and fast Fourier transform (FFT). The transmitter transmits data by performing an IFFT conversion. The receiver restores the original data by performing a conversion on the received signal. Said transmitter uses an IFFT transform to combine multiple subcarriers, and said receiver uses an FFT transform to split multiple subcarriers.

[39]

[40] I. Generation of the sequence

[41] According to an embodiment of the present invention, a pseudo-noise (PN) sequence is used as a sequence applied to a secondary synchronization signal (SSS). Said pseudo-noise (PN) sequence can be reproduced and has characteristics similar to a random sequence. The pseudo noise (PN) sequence is characterized as follows. (1) The repetition period is long enough. If a sequence has an infinitely long repetition period, then the sequence is a random sequence. (2) The number of zeros 0 is close to the number of units of 1 in one period. (3) The part having the length of the series 1 is 1/2, the part having the length of the series 2 is 1/4, the part having the length of the series 3 is 1/8, etc. Here, the length of a series is defined as the number of continuous identical characters. (4) The cross-correlation between sequences in one period is significantly small. (5) The entire sequence cannot be reproduced using small parts of the sequence. (6) Playback is possible using the proper playback algorithm.

[42] The pseudo noise (PN) sequence includes an m-sequence, a gold sequence, a Kasami sequence, etc. For clarity, the m-sequence will be considered as an example. In addition to the above characteristics, the m-sequence has additional characteristics in which the side lobes of the periodic autocorrelation are -1.

[43] An example of a generating polynomial for generating an m-sequence c _k can be expressed by the following formula.

[44] Mathematical expression 1

[Formula 1] with _k = x ⁵ + x ² +1 more than GF (2)

[45] where GF denotes the Galois Field, and GF (2) denotes a binary signal.

[46] The maximum length of the sequence generated by Formula 1 is 2 ⁵ -1 = 31. In this case, in accordance with the generation state, a total of 31 sequences can be generated. This coincides with the maximum number of sequences (i.e. 31) that can be generated using a cyclic shift after an arbitrary m-sequence generated according to Formula 1. This means that a maximum of 31 pieces of information can be transmitted. Even if the information is simple, more than 31 pieces of information cannot be transmitted.

[47] According to another embodiment of the present invention, if the m-sequence is defined as d (n), the set of S1 sequences for all available sequences can be expressed as S1 = {d ^m (k) | m is the sequence index}, where m = 0, 1, ..., N-1 and k = 0, 1, ..., N-1. N is N = 2 ⁿ -1, where n is the maximum degree. For example, in the case when it is generated by a generating polynomial according to Formula 1, n = 5 and N = 31.

[48] The new sequence g ^m (k) is defined by the formula g ^m (k) = d ^m (N-1-k), m = 0, 1, ..., N-1, k = 0, 1, ..., N- one. The set of S2 sequences is defined as S2 = {g ^m (k) | m is the sequence index}. The set of S3 sequences can be defined as S3 = {S1, S2}. The characteristics of the t-sequence are stored in S1 and S2. The random sequence property is maintained between S1 and S2. Therefore, a sequence having good correlation properties can be generated in an appropriate set of sequences, and the number of available sequences can increase without using additional memory or without increasing overhead.

[49] In particular, an m-sequence can be generated using an nth-degree generating polynomial, as shown below.

[50] Mathematical expression 2

[Formula 2] a ₀ x ⁿ + a ₁ x ^n-1 + ... + a _n-1 1

[51] where k = 0, 1, ..., n-1, and a _k = from 0 to 1.

[52] Using the sequence definition g ^m (k), said m-sequence can be transformed into one of the t-sequences generated as shown below.

[53] Mathematical expression 3

[Formula 3] a _n-1 x ^n-0 + a _n-2 x ^n-1 + ... + a ₀ x ⁿⁿ = a _n-1 x ⁿ + a _n-2 x ^n-1 + ... + a ₀ 1

[54] where k = 0, 1, ..., nl, and a _k = from 0 to 1. This means that the coefficients of the generating polynomial for generating the sequence are interchanged compared to Formula 2. this also means that the sequences mentioned are generated Formula 2 are interchanged in order. In this case, they say that the two formulas are inversely related. The inverse relation also holds when the degree of the generating polynomial is inverse (here the degree of the polynomial changes to nk). When using m-sequences, the generating polynomial can be selected to perform the inverse relationship.

[55] For example, if n = 5, the generating polynomial for generating t-sequences can be expressed as shown below.

[56] Mathematical expression 4

[Formula 4]

(1) x ⁵ + x ² +1

(2) x ⁵ x ³ +1

(3) x ⁵ + x ³ + x ² + x ¹ +1

(4) x ⁵ + x ⁴ + x ³ + x ² +1

(5) x ⁵ + x ⁴ + x ³ + x ¹ +1

(6) x ⁵ + x ⁴ + x ³ + x ¹ +1

[57] In this case, (1) and (2), (3) and (4), and (5) and (6) are in a pairwise relation that satisfies the inverse relation expressed by Formulas 2 and 3. The mentioned m-sequences may be selected to perform an inverse relationship.

[58] When a significantly longer sequence is used, said sequence can be divided into several parts by differently determining the initial shift of the sequence. In this case, each part of the sequence can be used in reverse order.

[59] Furthermore, when a significantly longer sequence is used, said long sequence can be inverse, and then said inverse sequence can be divided into several parts by differently determining the initial shift of the sequence.

[60] The above sequence may be used in multiple channels. The greater the number of available sequences, the higher the throughput of user equipment units (UEs).

[61] In an embodiment, the above sequence is used in a synchronization signal. Further, this sequence is used in the primary synchronization code (PSC) for the primary synchronization signal (PSS) or in the secondary synchronization code (SSC) for the secondary synchronization signal (SSS) . Moreover, said sequence is used in scrambling code. In this case, said sequence may be selected so that the secondary synchronization code (SSC) and the scrambling code satisfy the inverse relation.

[62] In another embodiment, the above sequence is used in a random access preamble. The mentioned random access preamble is used to request upstream radio resources. One sequence index corresponds to one possibility. The user equipment (UE) randomly selects any one of the sets of sequences and thus informs the base station (BS) of the existence of said user equipment (UE), or performs an operation such as a scheduling request or a band request. The random access procedure is a rivalry based procedure. Thus, there may be disagreement among user equipment units (UEs). To reduce disagreement among user equipment units (UEs) in a random access procedure, the number of random access preambles in the set should be large enough. For example, if random access preambles are configured using Formula 1, then there are 31 possibilities. If the random access preambles are configured using the S3 sequence definition, then there are 62 possibilities.

[63] In yet another embodiment, the aforementioned sequence can be used to transmit a channel quality indicator (CQI) or acknowledgment (ACK) / negative acknowledgment (NACK) signal. When a Formula 1 sequence is used, a total of 31 channel quality indicators (CQIs) or an ACK / NACK signal (> 4 bits) can be transmitted. When the S3 sequence is used, a total of 62 channel quality indicators (CQIs) or ACK / NACK signals (> 5 bits) can be transmitted.

[64] In yet another embodiment, the aforementioned sequence can be used using the base sequence for the reference signal. The reference signal may be classified into a demodulation reference signal for demodulating data or a sounding reference signal for uplink scheduling. The reference signal must have a large number of available sequences to ensure cell planning and coordination. For example, suppose a total of 170 sequences are required as a reference signal in the downstream direction. Then, when the 1.25 MHz band is used as the reference, the number of subcarriers occupied by the reference signal is 120 within the OFDM symbol, 5 ms long. If an m-sequence is used, then a total of 127 sequences can be generated using a polynomial of degree 7. When using the S3 sequence, a total of 252 sequences can be generated. Assume that a reference signal in the upstream direction is assigned to one resource block, including 12 subcarriers. Then, when an m-sequence is used, a total of 15 sequences can be generated using a 4th degree polynomial. When using the S3 sequence, a total of 30 sequences can be generated.

[65]

[66] II. Sync signal

[67] The synchronization signal will now be described. The technical properties of the present invention can be easily applied to a random access preamble or other control signals by those of ordinary skill in the art.

[68] FIG. 2 shows an example of a structure of a radio frame.

[69] Referring to FIG. 2, a radio frame includes 10 subframes. One subframe includes two slots. One slot includes multiple OFDM symbols in the time domain. Although one slot includes 7 OFDM symbols in FIG. 2, the number of OFDM symbols included in one slot may vary depending on the structure of a cyclic prefix (CP).

[70] The structure of the radio frame is for the purpose of example only. Thus, the number of subframes and the number of slots included in each subframe can be varied in various ways.

[71] The primary synchronization signal (PSS) is transmitted in the last OFDM symbol in each of the 0th slot and the 10th slot. The same primary synchronization code (PSC) is used by two primary synchronization signals (PSS). The primary synchronization signal (PSS) is used to obtain OFDM symbol synchronization (or slot synchronization) and is associated with a unique identifier in the cell identification group. Primary synchronization code (PSC) can be generated from the Zadoff-Chu (ZC) sequence. At least one primary synchronization code (PSC) exists in a wireless communication system.

[72] Said primary synchronization signal (PSS) comprises a primary synchronization code (PSC). When three primary synchronization codes (PSC) are reserved, the base station (BS) selects one of the three primary synchronization codes (PSC) and transmits the selected primary synchronization code (PSC) in the last OFDM symbol of the 0th slot and 10th slot as a signal primary synchronization (PSS).

[73] The secondary synchronization signal (SSS) is transmitted in an OFDM symbol, which is located immediately before said OFDM symbol for the primary synchronization signal (PSS). This means that the secondary synchronization signal (SSS) and the primary synchronization signal (PSS) are transmitted in adjacent (or consecutive) OFDM symbols. The secondary synchronization signal (SSS) is used to obtain frame synchronization and is connected to a cell identification group. The cell identifier may be uniquely determined by the cell identification group received from the secondary synchronization signal (SSS), and said unique identifier is received from the primary synchronization signal (PSS). A user equipment (UE) may obtain a cell identifier using a primary synchronization signal (PSS) and a secondary synchronization signal (SSS).

[74] One secondary synchronization signal (SSS) contains two secondary synchronization codes (SSC). One secondary synchronization code (SSC) may use a pseudo noise (PN) sequence (i.e., an m-sequence). For example, if one secondary synchronization signal (SSS) includes 64 subcarriers, then two pseudo noise (PN) sequences having a length of 31 are mapped to one secondary synchronization signal (SSS).

[75] The location or number of OFDM symbols in which the primary synchronization signal (PSS) and secondary synchronization signal (SSS) are located in the slot is shown in FIG. 2 only an example of the result, and thus may vary depending on the system.

[76] Figure 3 depicts an example of a physical mapping of two secondary synchronization codes (SSC) to a secondary synchronization signal (SSS).

[77] Referring to FIG. 3, if the number of subcarriers included in the secondary synchronization signal (SSS) is N, the length of the first secondary synchronization code (SSC) 1 and the length of the second secondary synchronization code (SSC) 2 are N / 2. The logical expression indicates the secondary synchronization code (SSC) in use. The physical expression indicates the subcarriers to which the secondary synchronization code (SSC) is displayed when the secondary synchronization code (SSC) is transmitted in the secondary synchronization signal (SSS). Sl (n) denotes the nth element of the first secondary synchronization code (SSC) 1. S2 (n) denotes the nth element of the second secondary synchronization code (SSC) 2. The first secondary synchronization code (SSC) 1 and the second secondary synchronization code ( SSC) 2 alternate with each other and are mapped to physical subcarriers in a crest type configuration. This mapping method is called distributed mapping.

[78] Figure 4 depicts another example of a physical mapping of two secondary synchronization codes (SSC) to a secondary synchronization signal (SSS).

[79] Referring to FIG. 4, the number of subcarriers included in the secondary synchronization signal (SSS) is N. The length of the first secondary synchronization code (SSC) 1 and the length of the second secondary synchronization code (SSC) 2 are N / 2. The logical expression indicates the secondary synchronization code (SSC) in use. The physical expression indicates the subcarriers to which the secondary synchronization code (SSC) is displayed when the secondary synchronization code (SSC) is transmitted in the secondary synchronization signal (SSS). Sl (n) denotes the nth element of the first secondary synchronization code (SSC) 1. S2 (n) denotes the nth element of the second secondary synchronization code (SSC) 2. The first secondary synchronization code (SSC) 1 and the second secondary synchronization code ( SSC) 2 are mapped to locally concentrated physical subcarriers. This mapping method is called localized mapping.

[80] If the number of subcarriers in the secondary synchronization signal (SSS) is 62 and the length of the pseudo noise (PN) code is 31, then one secondary synchronization code (SSC) has a total of 31 indexes. If the first secondary synchronization code (SSC) 1 can have indices from 0 to 30, and the second secondary synchronization code (SSC) 2 can have indices from 0 to 30, then only 961 (i.e. 31 × 31 = 961) part of the information can be delivered.

[81]

[82] III. Secondary Timing Code (SSC) Mapping to Secondary Timing Signal (SSS)

[83] FIG. 5 shows an example of mapping two secondary synchronization codes (SSC) to a secondary synchronization signal (SSS).

[84] Referring to FIG. 5, since two secondary synchronization signals (SSS) are transmitted in a radio frame, as shown in FIG. 2, both the first secondary synchronization signal (SSS) assigned to the 0th slot and the second secondary synchronization signal ( SSS) assigned to the 10th slot, use the combination of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2. In this case, the locations of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2 swap each other in the frequency domain. That is, when the combining (secondary synchronization code (SSC) 1, secondary synchronization code (SSC) 2) is used in the first secondary synchronization signal (SSS), the second secondary synchronization signal (SSS) changes the first secondary synchronization code (SSC) 1 and the second code secondary synchronization (SSC) 2 with each other and thus uses a combination (secondary synchronization code (SSC) 2, secondary synchronization code (SSC) 1).

[85] To determine the secondary synchronization signals (SSS), the interval between the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS) can be pre-set. Multi-frame averaging can be performed in accordance with the structure of the cyclic prefix (SR). Multi-frame averaging is an operation in which a plurality of secondary synchronization signals (SSS) are received using a plurality of radio frames, and then values received from respective secondary synchronization signals (SSS) are averaged. If the structure of the cyclic prefix (CP) is not known, then multi-frame averaging is performed for all structures of the cyclic prefix (CP). The secondary synchronization code (SSC) code moving structure is advantageous when the receiver determines the secondary synchronization signals (SSS) by performing multi-frame averaging. In this structure, the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS) use the same combination of secondary synchronization codes (SSC), and there is no change other than the locations of the secondary synchronization codes (SSC). Thus, when averaging is performed, the second secondary synchronization signal (SSS) simply moves and integrates the secondary synchronization codes (SSC). On the other hand, when a non-moving secondary synchronization code (SSC) structure is used, even if coherent detection using the primary synchronization signal (PSS) is performed, incoherent combining should be performed when the detection results are averaged. However, when coherent detection using the primary synchronization signal (PSS) is performed, an improvement in performance can be expected, since the optimal combination with the maximum ratio (max ratio ratio combining (MRC), i.e. coherent combining can be performed when the secondary synchronization codes (SSC) are integrated. It is well known that maximum ratio combining (MRC) is an optimal combination. Typically, there is a gain in signal-to-noise ratio (SNR) of the order of 3 dB with coherent combining compared to incoherent combining.

[86] Although the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2 are moved in the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS) in the frequency domain, this is for illustrative purposes only. Thus, the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2 can move in the time domain or code area.

[87] FIG. 6 shows another example of the mapping of two secondary synchronization codes (SSC) to a secondary synchronization signal (SSS). Binary phase shift keying (BPSK) is used here. Binary phase modulation (BPSK) is the M-ary phase modulation (phase shift keying, PSK) at M = 2. In binary phase modulation (BPSK), all or some parts of the radio signal are modulated with +1 or -1. Using M-ary phase modulation (M-PSK), additional information can be transmitted without affecting the characteristics of the determination of the sequence currently in use.

[88] Referring to FIG. 6, both the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS) use the combination of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2, all are modulated parts of the first secondary synchronization signal (SSS) with a value of +1, the first secondary synchronization code (SSC) 1 of the second secondary synchronization signal (SSS) is modulated with a value of +1, and the second secondary synchronization code (SSC) 2 of the second secondary signal is modulated Synchronizing (SSS) value of -1. That is, modulation may be performed by changing phases between the secondary synchronization codes (SSC) used in one synchronization channel (SCH), or may be performed by changing phases between two synchronization channels (SCH). This is called differential modulation.

[89] Typically, to determine sequences that have the modulation mentioned, a signal (ie, a reference signal or primary synchronization code (PSC)) is required for phase support. That is, coherent detection is required. However, when differential modulation is performed to determine frame boundaries in a single secondary synchronization signal (SSS), both coherent detection and incoherent detection are possible.

[90]

[91] IV. Secondary Synchronization Signal Scrambling (SSS)

[92] Now, scrambling of a secondary synchronization signal (SSS) using a scrambling code associated with a primary synchronization code (PSC) will be discussed.

[93] The secondary synchronization signal (SSS) is scrambled using a scrambling code. Said scrambling code is a binary sequence associated with a primary synchronization code (PSC), and is mapped one-on-one to the primary synchronization code (PSC). In other words, the scrambling code depends on the primary synchronization code (PSC).

[94] Scrambling of the secondary synchronization signal (SSS) is used to solve the ambiguity caused by the detection of the secondary synchronization code (SSC). For example, suppose that the secondary synchronization code (SSC) combination used in the secondary synchronization signal (SSS) of cell A is (secondary synchronization code (SSC) 1, secondary synchronization code (SSC) 2) = (a, b), and the secondary synchronization code (SSC) combination used in the secondary synchronization signal (SSS) of cell B is (secondary synchronization code (SSC) 1, secondary synchronization code (SSC) 2) = (c, d). In this case, if the user equipment (UE) belonging to cell A receives an incorrect secondary synchronization code (SSC) combination, i.e. (secondary synchronization code (SSC) 1, secondary synchronization code (SSC) 2) = (a, d) , then this is called ambiguity. That is, after the user equipment (UE) determines the primary synchronization signal (PSS), a scrambling code is used to distinguish the secondary synchronization signal (SSS) corresponding to the cell of said user equipment (UE).

[95] Fig. 7 depicts the structure of a secondary synchronization signal (SSS) in accordance with an embodiment of the present invention.

[96] Referring to FIG. 7, both the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS) use the combination of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2. In this case the locations of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2 change in the frequency domain. That is, when the combining (secondary synchronization code (SSC) 1, secondary synchronization code (SSC) 2) is used in the first secondary synchronization signal (SSS), the second secondary synchronization signal (SSS) changes the first secondary synchronization code (SSC) 1 and the second code secondary synchronization (SSC) 2 with each other and thus uses combining (secondary synchronization code (SSC) 2, secondary synchronization code (SSC) 1).

[97] Secondary synchronization codes (SSC) of the respective secondary synchronization signals (SSS) are scrambled using various scrambling codes. The first secondary synchronization code (SSC) 1 of the first secondary synchronization signal (SSS) is scrambled by the first scrambling code. The second secondary synchronization code (SSC) 2 of the first secondary synchronization signal (SSS) is scrambled by the second scrambling code. Second Secondary Synchronization Code (SSC) 2 of the second secondary synchronization signal (SSS) is scrambled by a third scrambling code. The first secondary synchronization code (SSC) 1 of the second secondary synchronization signal (SSS) is scrambled with a fourth scrambling code.

[98] Since each secondary synchronization code (SSC) is scrambled with a different scrambling code, an averaging effect can be obtained. For example, suppose that the secondary synchronization code (SSC) for combining the first secondary synchronization signal (SSS) of cell A is (secondary synchronization code (SSC) 1_A, secondary synchronization code (SSC) 2_A) = (a, b), secondary synchronization code ( SSC) combining the second secondary synchronization signal (SSS) of cell A is equal to (secondary synchronization code (SSC) 2_A, secondary synchronization code (SSC) 1_A) = (b, a), secondary synchronization code (SSC) combining the first secondary synchronization signal (SSS ) cell B is equal to (secondary synchronization code (SSC) 1_B, secondary sync code reset (SSC) 2_B) = (s, d), secondary synchronization code (SSC) combining the second secondary synchronization signal (SSS) is (secondary synchronization code (SSC) 2_B, secondary synchronization code (SSC) 1_B) = (d, s ), cell A is the cell in which the user equipment of the user (UE) is currently located (that is, said cell A is the cell for determination), and cell B is the neighboring cell (that is, said cell B is the cell that interferes) . Then, the secondary synchronization code interference (SSC) 1_A and the secondary synchronization code interference (SSC) 2_A are c and d and thus become equal regardless of the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS). Therefore, the effect of averaging interference cannot be achieved. However, when each secondary synchronization code (SSC) is scrambled using a different scrambling code, the effect of averaging interference can be achieved due to the interference effect of different codes.

[99] Therefore, since different scrambling codes are used for the same secondary synchronization code (SSC) for each subframe, the ambiguity arising from the determination of the secondary synchronization code (SSC) can be reduced. In addition, the effect of averaging interference can be achieved when multi-frame averaging is performed.

[100] Here, the secondary synchronization code (SSC) structure represents a logical structure. When mapping to physical subcarriers is performed, a distributed mapping or a localized mapping may be used. In addition, physical mapping may be performed before or after scrambling performed in a logical structure.

[101] Fig. 8 depicts a secondary synchronization signal (SSS) structure in accordance with another embodiment of the present invention.

[102] Referring to FIG. 8, both the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS) use the combination of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2. In this case the locations of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2 change in the frequency domain. That is, when the combining (secondary synchronization code (SSC) 1, secondary synchronization code (SSC) 2) is used in the first secondary synchronization signal (SSS), the second secondary synchronization signal (SSS) swaps the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2 with each other and thus uses the combination (secondary synchronization code (SSC) 2, secondary synchronization code (SSC) 1).

[103] Scrambling is performed using two scrambling codes corresponding to the number of secondary synchronization codes (SSC) included in one secondary synchronization signal (SSS). The first secondary synchronization code (SSC) 1 of the first secondary synchronization signal (SSS) is scrambled by the first scrambling code. The second secondary synchronization code (SSC) 2 of the first secondary synchronization signal (SSS) is scrambled by the second scrambling code. Second Secondary Synchronization Code (SSC) 2 of the second secondary synchronization signal (SSS) is scrambled by the first scrambling code. The first secondary synchronization code (SSC) 1 of the second secondary synchronization signal (SSS) is scrambled by the second scrambling code.

[104] From the point of view of the physical expression in which the actual subcarriers are mapped, two secondary synchronization codes (SSC) change locations for the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS), but the locations of said scrambling codes do not change . From a logical expression point of view, the scrambling codes are respectively applied to the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2, acting so that said scrambling codes respectively applied to the second secondary synchronization code (SSC) 2 and the first secondary synchronization code (SSC) 1 of the second secondary synchronization signal (SSS) are changed. Compared to the embodiment of FIG. 7, the number of required scrambling codes is reduced.

[105] Fig. 9 shows a structure of a secondary synchronization signal (SSS) in accordance with another embodiment of the present invention.

[106] Referring to FIG. 9, the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS) use the same combination of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2. That is, if the first secondary synchronization signal (SSS) uses the combination (secondary synchronization code (SSC) 1, the secondary synchronization code (SSC) 2), the second secondary synchronization signal (SSS) also uses the mentioned combination (secondary synchronization code (SSC) 1, the secondary synchronization code (SSC) 2). The locations of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2 do not change with each other in the frequency domain. In the frequency domain, the locations of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2 are equal to each other in the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS).

[107] Scrambling is performed using two scrambling codes corresponding to the number of secondary synchronization codes (SSC) included in one secondary synchronization signal (SSS). In this case, the locations of the scrambling codes used for the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS) change with each other. The first secondary synchronization code (SSC) 1 of the first secondary synchronization signal (SSS) uses the first scrambling code. The second secondary synchronization code (SSC) 2 of the first secondary synchronization signal (SSS) uses a second scrambling code. The second secondary synchronization code (SSC) 2 of the second secondary synchronization signal (SSS) uses a second scrambling code. The first secondary synchronization code (SSC) 1 of the second secondary synchronization signal (SSS) uses the first scrambling code.

[108] In contrast to the embodiment of FIG. 8, the secondary synchronization codes (SSC) do not change their locations for the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS), but they change the locations of said scrambling codes. That is, for the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS), the locations of the secondary synchronization codes (SSC) or scrambling codes change with each other.

[109] Figure 10 depicts the structure of a secondary synchronization signal (SSS) in accordance with another embodiment of the present invention.

[110] Referring to FIG. 10, in the frequency domain, the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2 have the same location in the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS) , in addition, the second secondary synchronization code (SSC) of the second secondary synchronization signal (SSS) is a secondary synchronization code 2 (-SSC2). That is, the first secondary synchronization signal (SSS) uses (secondary synchronization code (SSC) 1, the secondary synchronization code (SSC) 2), and the second secondary synchronization signal (SSS) uses (secondary synchronization code (SSC) 1, the secondary synchronization code 2 (-SSC2)).

[111] The modulation scheme used here is binary phase modulation (BPSK). A higher order modulation scheme may also be used. For example, when using a Quadrature phase shift key (QPSK), it is possible to change the phase by modulating in the form +1, -1, + j, -j. The first secondary synchronization signal (SSS) can use (secondary synchronization code (SSC) 1, secondary synchronization code (SSC) 2), and the second secondary synchronization signal (SSS) uses (secondary synchronization code (SSC) 1, -j secondary synchronization code 2 (-jSSC2)).

[112] It is difficult to randomize interference if the secondary synchronization code (SSC) of combining the first secondary synchronization signal (SSS) is equal to the secondary synchronization code (SSC) of combining the second secondary synchronization signal (SSS) in a multi-cell environment. Thus, if the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) -SSC2 do not move with each other, then the scrambling codes move with each other. In this case, the differential modulation information of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) - SSC2 in the second secondary synchronization signal (SSS) may represent frame boundary information. Therefore, in order to determine 392 (= 14 × 14 × 2) signals, the detection operation is performed 392 times when differential modulation is not performed. On the other hand, when differential modulation is performed, the detection operation is performed 196 (= 14 × 14) times, and two pieces of information can be determined using said differential modulation. All detection characteristics are determined by a detection operation performed 196 times, instead of differential modulation. Thus, all characteristics can be further improved when differential modulation is performed. In addition, since both the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS) use the same first and second scrambling codes, the secondary synchronization code (SSC) 1 and the secondary synchronization code (SSC) 2, combining can be performed with maximum ratio (MRC).

[113] Although differential modulation is used for the second secondary synchronization code (SSC) SSC2 of the second secondary synchronization signal (SSS), this is for illustrative purposes only. For example, the first secondary synchronization signal (SSS) may use (SSC1, SSC2), and the second secondary synchronization signal (SSS) may use (-SSC1, -SSC2). The first secondary synchronization signal (SSS) can use (SSC1, SSC2), and the second secondary synchronization signal (SSS) can use (-SSC1, SSC2). The first secondary synchronization signal (SSS) can use (-SSC1, SSC2), and the second secondary synchronization signal (SSS) can use (SSC1, -SSC2). The first secondary synchronization signal (SSS) may use (SSC1, -SSC2), and the second secondary synchronization signal (SSS) may use (-SSC1, SSC2). The first secondary synchronization signal (SSS) can use (-SSC1, -SSC2), and the second secondary synchronization signal (SSS) can use (SSC1, SSC2). The first secondary synchronization signal (SSS) can use (SSC1, -SSC2), and the second secondary synchronization signal (SSS) can use (SSC1, SSC2). The first secondary synchronization signal (SSS) can use (-SSC1, SSC2), and the second secondary synchronization signal (SSS) can use (SSC1, SSC2). In addition, here various other modulation combinations may also be used.

[114] FIG. 11 illustrates a structure of a secondary synchronization signal (SSS) in accordance with another embodiment of the present invention.

[115] Referring to FIG. 11, both the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS) use the combination of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2. In this case the locations of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2 change in the frequency domain. That is, when combining (secondary synchronization code (SSC) 1, secondary synchronization code (SSC) 2) is used in the first secondary synchronization signal (SSS), the second secondary synchronization signal (SSS) changes the first secondary synchronization code (SSC) 1 and the second the secondary synchronization code (SSC) 2 with each other and thus uses the combination (secondary synchronization code (SSC) 2, secondary synchronization code (SSC) 1). The first secondary synchronization code (SSC) of the second secondary synchronization signal (SSS) is modulated by differential modulation into a secondary synchronization code (-SSC1). That is, the first secondary synchronization signal (SSS) uses (secondary synchronization code (SSC) 1, the secondary synchronization code (SSC) 2), and the second secondary synchronization signal (SSS) uses (secondary synchronization code (SSC) 2, - the secondary synchronization code (-SSC1)).

[116]

[117] V. Scrambling using multiple primary synchronization codes (PSC)

[118] An example of configuring a scrambling code when multiple primary synchronization codes (PSCs) are used will now be considered. For clarity, it is assumed that three primary synchronization codes (PSCs) are used, and scrambling codes associated with respective primary synchronization codes (PSCs) are defined as Px-a1, Px-a2, Px-b1, and Px-b2, respectively. Here, “x” denotes the primary synchronization code index (PSC), “a” denotes the first secondary synchronization signal (SSS), “b” denotes the second secondary synchronization signal (SSS), “1” denotes the first secondary synchronization code (SSC) 1, and “2” denotes the second secondary synchronization code (SSC) 2. That is, P1-a1 denotes a scrambling code associated with the first primary synchronization code (PSC) and used in the first secondary synchronization code (SSC) 1 of the first secondary synchronization signal (SSS) , P2-b2 denotes a scrambling code associated with second m primary synchronization code (PSC) and used in the second secondary synchronization code (SSC) 2 of the second secondary synchronization signal (SSS), P3-a1 denotes the scrambling code associated with the third primary synchronization code (PSC) and used in the first secondary synchronization code ( SSC) 1 of the first secondary synchronization signal (SSS). When it is said that a scrambling code is associated with a primary synchronization code (PSC), this means that said scrambling code is generated differently in accordance with a primary synchronization code (PSC). For example, said scrambling code may be generated using a different cyclic shift in accordance with the cell identifier (ID) using said primary synchronization code (PSC).

[119] <When using 6 scrambling codes for 3 primary synchronization codes (PSC)>

[120] For each primary synchronization code (PSC), the scrambling codes can be configured such that (Px-a1, Px-a2) = (Px-b1, Px-b2). (Px-a1, Px-a2) - one-to-one is displayed on the corresponding primary synchronization codes (PSC). That is, for said three primary synchronization codes (PSCs), six scrambling codes can be determined as follows.

[121] Primary Synchronization Code (PSC) 1 → (P1-a1, P1-a2)

[122] Primary synchronization code (PSC) 2 → (P2-a1, P2-a2)

[123] Primary synchronization code (PSC) 3 → (P3-a1, P3-a2)

[124] Fig. 12 depicts a secondary synchronization signal (SSS) structure for a primary synchronization code (PSC) 1. Fig. 13 depicts a secondary synchronization signal (SSS) signal structure for a primary synchronization code (PSC) 2. Fig. 14 depicts a secondary signal structure. synchronization (SSS) for primary synchronization code (PSC) 3.

[125] Referring to FIG. 12 to 14, for each primary synchronization code (PSC), the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS) both use the combination of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2. In this case, the locations of the first secondary synchronization code 1 and the second secondary synchronization code 2 are changed. That is, if the first secondary synchronization signal (SSS) uses combining (secondary synchronization code (SSC) 1, secondary synchronization code (SSC) 2), the second secondary synchronization signal (SSS) moves the first secondary synchronization code 1 and the second secondary synchronization code 2 with each other and thus uses combining (secondary synchronization code (SSC) 2, secondary synchronization code (SSC) 1).

[126] Scrambling is performed using two scrambling codes corresponding to the number of secondary synchronization codes (SSC) included in one secondary synchronization signal (SSS).

[127] In said primary synchronization code (PSC) 1 of FIG. 12, the first secondary synchronization code 1 of the first secondary synchronization signal (SSS) uses the scrambling code P1-a1, the second secondary synchronization code (SSC) 2 of the first secondary synchronization signal (SSS) uses the scrambling code P1-a2, the second secondary synchronization code (SSC) 2 of the second secondary synchronization signal (SSS) uses the scrambling code P1-a1, and the first secondary synchronization code (SSC) 1 of the second secondary synchronization signal (SSS) uses the scrambling code P1-a2 .

[128] In said primary synchronization code (PSC) 2 of FIG. 13, the first secondary synchronization code (SSC) 1 of the first secondary synchronization signal (SSS) uses a scrambling code P2-a1, the second secondary synchronization code (SSC) 2 of the first secondary synchronization signal (SSS) uses a P2-a2 scrambling code, a second secondary synchronization code (SSC) 2 of a second secondary synchronization signal (SSS) uses a P2-a1 scrambling code, and a first secondary synchronization code (SSC) 1 of a second secondary synchronization signal (SSS) uses a scrambling code code P2-a2.

[129] In said primary synchronization code (PSC) 3 of FIG. 14, the first secondary synchronization code (SSC) 1 of the first secondary synchronization signal (SSS) uses the scrambling code P3-a1, the second secondary synchronization code (SSC) 2 of the first secondary synchronization signal ( SSS) uses the P3-a2 scrambling code, the second secondary synchronization code (SSC) 2 of the second secondary synchronization signal (SSS) uses the P3-a1 scrambling code, and the first secondary synchronization code (SSC) 1 of the second secondary synchronization signal (SSS) uses the scrambling code P3-a2.

[130] When mapping to a physical channel is performed, said two secondary synchronization codes (SSC) change their locations to a first secondary synchronization signal (SSS) and a second secondary synchronization signal (SSS), but do not change the locations of said scrambling codes.

[131] In this method, the scrambling codes associated with the three primary synchronization codes (PSC) are different from each other with respect to both the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2. This can reduce ambiguity and also bring the effect of randomization interference. For example, suppose that combining the secondary synchronization code (SSC) of the first secondary synchronization signal (SSS) of cell A is (P1-a1⊗SSC1_A, P1-a2⊗SSC2_A),

combining the secondary synchronization code (SSC) of the second secondary synchronization signal (SSS) of cell A equal to (P1-a1⊗SSC2_A, P1-a2⊗SSCl_A),

combining the secondary synchronization code (SSC) of the first secondary synchronization signal (SSS) of cell B equal to (P2-a1⊗SSC1_B, P2-a2⊗SSC2_B),

combining the secondary synchronization code (SSC) of the second secondary synchronization signal (SSS) of cell B equal to (P2-a1⊗SSC2_B, P2-a2⊗SSCl_B),

cell A is the cell where the user equipment (UE) is currently located, and cell B is the neighboring cell. Then the interference of the first secondary synchronization signal (SSS) of cell A is equal to (P2-a1⊗SSC1_B, P2-a2⊗SSC2_B), and the interference of the second secondary synchronization signal (SSS) is equal to (P2-a1⊗SSC2_B, P2-a2⊗SSC1_B).

In practice, since the different code acts as a hindrance to the first secondary synchronization code SSC1 and the second secondary synchronization code SSC2 with respect to the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS), the benefits of the effect of interference averaging and multi-frame averaging can be achieved without deterioration. Accordingly, the detection characteristics of the secondary synchronization signals (SSS) can be improved.

[132]

[133] <When using 3 scrambling codes for 3 primary synchronization codes (PSC)>

[134] For each primary synchronization code (PSC), the scrambling codes may be configured such as (Px-a1, Px-a2) = (Px-b1, Px-b2). (Px-a1, Px-a2) - one-to-one mapped corresponding primary synchronization codes (PSC). One of the two scrambling codes mapped to one primary synchronization signal (PSS) is equal to one of the scrambling codes mapped to the other primary synchronization signal (PSS). For example, the relation Px_a2 = P [mod (x + 1.3) +1] _a1 is supported. Here, 'mod' denotes a modulo operation. For example, three scrambling codes for three primary synchronization codes (PSCs) may be determined as follows.

[135] Primary synchronization code (PSC) 1 → (P1-a1, P1-a2)

[136] Primary synchronization code (PSC) 2 → (P2-a1 = P1-a2, P2-a2)

[137] Primary synchronization code (PSC) 3 → (P3-a1 = P2-a2, P3-a2 = P1-a1)

[138] In practice, three scrambling codes P1-a1, P1-a2, and P2-a2 are required. If (P1-a1, P1-a2, P2-a2) = (a1, a2, a3), then the three scrambling codes mentioned can be expressed as follows.

[139] Primary synchronization code (PSC) 1 → (a1, a2)

[140] Primary synchronization code (PSC) 2 → (a2, a3)

[141] Primary synchronization code (PSC) 3 → (a3, a1)

[142] The number of required scrambling codes can be reduced by cyclically shifting said three scrambling codes for corresponding primary synchronization codes (PSCs). By reducing the number of scrambling codes, the memory capacity of a base station (BS) or user equipment (UE) can be saved.

[143] If M primary synchronization codes (PSC) are used, then said scrambling codes can be summarized as follows.

[144] Primary synchronization code (PSC) 1 → (a1, a2)

[145] Primary synchronization code (PSC) 2 → (a2, a3)

[146] ...

[147] Primary synchronization code (PSC) M → (aM, a1)

[148] FIG. 15 shows the structure of the secondary synchronization signal (SSS) for the primary synchronization code (PSC) 1. FIG. 16 shows the structure of the secondary synchronization signal (SSS) for the primary synchronization code (PSC) 2. FIG. 17 shows the structure of the secondary signal synchronization (SSS) for primary synchronization code (PSC) 3.

[149] Referring to Figs. 15 to 17, for each primary synchronization code (PSC), both the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS) use the combination of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2. In this case, the locations of the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2 change in the frequency domain. That is, when combining (SSC1, SSC2) is used in the first secondary synchronization signal (SSS), the second secondary synchronization signal (SSS) changes the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2 with each other and such uses union (SSC2, SSC1).

[150] Scrambling is performed using two scrambling codes corresponding to the number of secondary synchronization codes (SSC) included in one secondary synchronization signal (SSS).

[151] In the primary synchronization code (PSC) 1 of FIG. 15, the first secondary synchronization code (SSC) 1 of the first secondary synchronization signal (SSS) uses the scrambling code P1-a1, the second secondary synchronization code (SSC) 2 of the first secondary synchronization signal (SSS) ) uses the scrambling code P1-a2, the second secondary synchronization code (SSC) 2 of the second secondary synchronization signal (SSS) uses the scrambling code P1-a1, and the first secondary synchronization code (SSC) 1 of the second secondary synchronization signal (SSS) uses the scrambling code P1 -a2.

[152] In the primary synchronization code (PSC) 2 of FIG. 16, the first secondary synchronization code (SSC) 1 of the first secondary synchronization signal (SSS) uses the scrambling code P1-a2, the second secondary synchronization code (SSC) 2 of the first secondary synchronization signal (SSS) ) uses a P2-a2 scrambling code, a second secondary synchronization code (SSC) 2 of a second secondary synchronization signal (SSS) uses a P2-a1 scrambling code, and a first secondary synchronization code (SSC) 1 of a second secondary synchronization signal (SSS) uses a P2 scrambling code -a2.

[153] In the primary synchronization code (PSC) 3 of FIG. 17, the first secondary synchronization code (SSC) 1 of the first secondary synchronization signal (SSS) uses a scrambling code P2-a2, the second secondary synchronization code (SSC) 2 of the first secondary synchronization signal (SSS) ) uses the scrambling code P1-a1, the second secondary synchronization code (SSC) 2 of the second secondary synchronization signal (SSS) uses the scrambling code P3-a1, and the first secondary synchronization code (SSC) 1 of the second secondary synchronization signal (SSS) uses the scrambling code P3 -a2.

[154] In terms of mapping to physical subcarriers, said two secondary synchronization codes (SSC) change their locations to a first secondary synchronization signal (SSS) and a second secondary synchronization signal (SSS), but do not change the locations of said scrambling codes.

[155] In this method, the scrambling codes associated with the three primary synchronization codes (PSC) are different from each other with respect to both the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2. This may reduce ambiguity and also bring the effect of randomization interference. For example, suppose that combining the secondary synchronization code (SSC) of the first secondary synchronization signal (SSS) of cell A is (P1-a1⊗SSC1_A, P1-a2⊗SSC2_A),

combining the secondary synchronization code (SSC) of the second secondary synchronization signal (SSS) of cell A equal to (P1-a1 аSSC2_A, P1-a2⊗SSC1_A),

combining the secondary synchronization code (SSC) of the first secondary synchronization signal (SSS) of cell B equal to (P1-a2⊗SSC1_B, P2-a2⊗SSC2_B),

combining the secondary synchronization code (SSC) of the second secondary synchronization signal (SSS) of cell B equal to (P1-a2⊗SSC2_B, P2-a2⊗SSC1_B),

cell A is the cell where the user equipment (UE) is currently located, and cell B is the neighboring cell. Then the interference of the first secondary synchronization signal (SSS) of cell A is equal to (P1-a2⊗SSC1_B, P2-a2⊗SSC2_B),

and the interference of the second secondary synchronization signal (SSS) is equal

(P1-a2⊗SSC2_B, P2-a2⊗SSC1_B).

In practice, since the different code acts as a hindrance to the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2 with respect to the first secondary synchronization signal (SSS) and the second secondary synchronization signal (SSS), the advantages of the interference averaging effect and multi-frame averaging can be achieved without degradation. Accordingly, the determination of the secondary synchronization signals (SSS) can be improved.

[156] In the above example, in which six or three scrambling codes are used for three primary synchronization codes (PSC), moving only the secondary synchronization code (SSC) has been considered to facilitate explanation. However, in addition to the above, differential modulation can be performed, and the movement of the secondary synchronization code (SSC) can be performed in combination with differential modulation. For example, the same can be applied in various cases, such as the case where the first secondary synchronization signal (SSS) uses (SSC1, SSC2) and the second secondary synchronization signal (SSS) uses (SSC2, SSC1), in the case where the first signal secondary synchronization signal (SSS) uses (SSC1, SSC2) and the second secondary synchronization signal (SSS) uses (SSC3, SSC4), in the case where the first secondary synchronization signal (SSS) uses (SSC1, SSC2) and the second secondary synchronization signal (SSS ) uses (SSC1, SSC3), and in the case where the first secondary synchronization signal (SSS) uses (S SC1, SSC2) and the second secondary synchronization signal (SSS) uses (SSC3, SSC2). When the first secondary synchronization signal (SSS) uses (SSC1, SSC2) and the second secondary synchronization signal (SSS) uses (SSC1, SSC3), the secondary synchronization code SSC1 collides. The effect resulting from the collision of the secondary synchronization code (SSC) can be reduced by changing the scrambling codes. The same also applies where SSC2 collision occurs when the first secondary synchronization signal (SSS) uses (SSC1, SSC2) and the second secondary synchronization signal (SSS) uses (SSC3, SSC2).

[157]

[158] VI. Method for configuring scrambling codes

[159] Any code in association with the primary synchronization code (PSC) can be used as a scrambling code. The technical features of the present invention are not limited to this.

[160] Said scrambling code may be a pseudo noise (PN) code used in the secondary synchronization code (SSC).

[161] If the number of pieces of information transmitted by the secondary synchronization signal (SSS) is 340, then the secondary synchronization code (SSC) can be configured as follows.

For example, if it is assumed that a pseudo-noise (PN) code having a length of 31 is used for the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2, then the available code indices take values from 0 to 30, that is, in total 31 index. If the first secondary synchronization code (SSC) 1 uses indices from 0 to 13, then the second secondary synchronization code (SSC) 2 uses indices from 14 to 27, and the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2 may vary, the number of possible combinations is 14 × 14 × 2 = 392. Therefore, a pseudo-noise (PN) code having indices 28, 29 and 30 can be used as said scrambling code. For another example, it is permissible that the index of the second secondary synchronization code (SSC) 2 is always greater than the index of the first secondary synchronization code (SSC) 1. If the first secondary synchronization code (SSC) 1 has indices from 0 to 17, then the second secondary code synchronization (SSC) 2 has indices from 1 to 18, and the first secondary synchronization code (SSC) 1 and the second secondary synchronization code (SSC) 2 can change, then the number of possible combinations is 19С2 × 2 = 342. Therefore, if six indices from the remaining indices from 19 to 30 are selected, then six scrambling codes can be obtained. If three indices are selected, then three scrambling codes can be obtained.

[162] Now, suppose that the number of pieces of information transmitted by the secondary synchronization signal (SSS) is 680. If the index of the second secondary synchronization code (SSC) 2 is always greater than the index of the first secondary synchronization code (SSC) 1, then the number possible combinations is 27C2 × 2 = 702, where the first secondary synchronization code (SSC) 1 has indices from 0 to 26, the second secondary synchronization code (SSC) 2 has indices from 1 to 27, and the change between the first secondary synchronization code (SSC) is used ) 1 and the second secondary synchronization code (SSC) 2. Correspondingly etstvenno three scrambling codes can be obtained by selecting among the three indices index of 28 to 30.

[163] The scrambling code is selected from the currently used sequence set. Alternatively, the sequence is selected from said current set of sequences used, and subsequently said sequence to be used is changed. For example, when an m-sequence is used, said m-sequence can be used as a scrambling code using inverse operation, compression, cyclic expansion, cyclic shift, etc. That is, in Formula 4, the sequence (1) and the sequence (2) have feedback from each other. In this case, sequence (1) can be used as a secondary synchronization code (SSC), and sequence (2) can be used as a scrambling code. When said pair of feedback sequences is selected as a scrambling code, the secondary synchronization code (SSC) and said scrambling code can provide m-sequence communication. In addition, the implementation is simple and memory space can be saved.

[164] Fig. 18 is a graph depicting a cumulative distribution function (CDF) of a cross-correlation distribution for all possible collisions in two cells.

[165] Referring to FIG. 18, the proposed method illustrates similar characteristics of a random binary code. However, to use random binary code as a scrambling code, a code generator or memory is additionally required. On the contrary, the proposed method does not incur additional overhead. This is possible because the proposed method only requires reconfiguration of the memory addresses.

[166] Now suppose that the m-sequence of the generating polynomial x ⁵ + x ² +1 of Formula 1 is used as a secondary synchronization code (SSC). In order for a user equipment (UE) to determine a secondary synchronization code (SSC), said sequence must be directly stored in a code or memory generator capable of generating a sequence used in the secondary synchronization code (SSC). Said m-sequence generated by Formula 1 undergoes a cyclic shift to obtain a total of 31 sequences. Instead of generating each secondary synchronization code (SSC) to determine the code by the code generator, if one m-sequence is stored in memory and only the memory address is assigned and used, then only one t-sequence having a length of 31 must be stored in memory. If the mentioned sequence is used in the reverse order, then only the order for indicating the memory address needs to be changed and used.

[167] For example, suppose that the t-sequence generated by Formula 1 has the form (a) = {1, 1, -1, 1, -1, -1, 1, 1, -1, -1, - 1, -1, -1, 1, 1, 1, -1, -1, 1, -1, -1, -1, 1, -1, 1, -1, 1, 1, 1, 1, - one}. An equivalent sequence - (a) may also be used. The remaining 30 sequences can be generated by performing cyclic shifts 30 times on sequence (a). Thus, only memory is needed to store sequence (a). To use sequences with feedback, it is enough to use, only once, a memory for storing sequence (a) or a code generator to generate sequence (a).

[168] However, if the sequence mentioned is not inverse and other types of sequences (eg, random sequence, computer search sequence, etc.) other than the m-sequence are used, then an additional memory is required for storing six scrambling codes associated with three codes primary synchronization (PSC). That is, although it is sufficient to store one sequence having a length of 31 in memory when feedback sequences are used, additional memory is required to store six sequences having a length of 31 when different sequences are used.

[169] When choosing a scrambling code, an excellent property can be achieved by generating an m-sequence after selecting a generating polynomial satisfying Formulas 2 and 3 above (or after changing the order of the coefficients of the polynomial in the mentioned order nk). When the generated m-sequence, x ⁵ + x ² +1 of Formula 1 is inverse, the mentioned sequence is converted to one of the m-sequences generated by x ⁵ + x ³ +1, which is called the pair ratio. For example, when a sequence that is generated x ⁵ + x ² +1 and is cyclically shifted 0 times is reversed, the resulting sequence is identical to the sequence generated by x ⁵ + x ³ +1 and cyclically shifted 26 times. Thus, when a pair of feedback sequences is selected as a scrambling code, the user equipment (UE) can be easily commissioned and the memory capacity can be saved.

[170]

[171] VII. SSC2 based scrambling based on SSC1

[172] Now, applications of the scrambling sequence definition used in the secondary synchronization code (SSC) 2 according to the sequence index used in the secondary synchronization code (SSC) 1 (ie, the use of inverse-m) will be considered.

[173] To solve the additional problem of ambiguity, when searching for a neighboring cell, there is a method for selecting and using a scrambling sequence, one-to-one corresponding to the index of the sequence used in the first secondary synchronization code (SSC) 1, and the combination of two codes (for example , (SSC1, SSC2)) is used in the secondary synchronization signal (SSS). In this case, for example, regarding the aforementioned length of the 31 m-sequence (31 sequence index is possible) using the generating polynomial x ⁵ + x ² +1, the sequence for use corresponding to the index of the mentioned m-sequence can be made inverse. For example, if the index of the first secondary synchronization code (SSC) 1 is 0, then said sequence can be reversed for use as a scrambling code for the second secondary synchronization code SSC 2. Alternatively, when SSC2 based on SSC1 is scrambled, all or some parts of the sequence, used in said secondary synchronization code (SSC) 1 can be made inverse for use as scrambling codes. As a result, the sequence used in the secondary synchronization code (SSC) 1 can be reversed for use as a scrambling secondary synchronization code (SSC) 2. This is not limited to the number of scrambling codes, a one-to-one mapping ratio, etc. In addition, generating polynomials in feedback can be selected.

[174] A case is now disclosed in which the above applies to [scrambling based on a primary synchronization code (PSC) + scrambling based on a secondary synchronization code (SSC) 1].

[175] Since the inverse-m is applied to scrambling based on a secondary synchronization code (SSC) 1 in this case, for convenience, a sequence based on a primary synchronization code (PSC) can use an m-sequence of length 63 and perforate said sequence, if necessary, or two different kinds of m-sequences of different generating polynomials can be used. The scrambling secondary synchronization code (SSC) can be expressed as follows.

[176] P⊗ (SSC1, SSC2) -P⊗ (si, sj)

[177] or (P⊗SSC1, P⊗SSC2) = (P⊗si, P⊗sj),

[178] or (P1⊗SSC1, P2⊗SSC2) = (P1⊗si, P2⊗sj).

[179] Here, P denotes a scrambling code based on a primary synchronization code (PSC). Note that P does not change whether scrambling is performed on all parts of the secondary synchronization code (SSC) or whether scrambling is performed separately on each part of said secondary synchronization code (SSC).

[180] Mentioned scrambling based on the secondary synchronization code (SSC) 1 is applied to SSC2, as explained by the following expression.

[181] P⊗ (SSC1, SCR1⊗SSC2) = P⊗ (si, rev (si) ⊗sj),

[182] or (Р⊗SSC1, SCR1⊗P⊗SSC2) = (P⊗si, SCR1⊗P⊗sj),

[183] or (P1⊗SSC1, SCR1⊗P2⊗SSC2) = (P1⊗SCR1⊗P2⊗sj).

[184] Here, SCR1 denotes a scrambling code based on a secondary synchronization code (SSC) 1, and rev (-) denotes an inverse operation (or inverse-m). Of course, as described above, the above operation is equivalent to the selection and use of generating polynomials (here, x ⁵ + x ³ +1) having feedback.

[185] In the present example, si is directly inverse for scrambling with sj. However, the present invention is not limited to this, and therefore feedback generating polynomials or feedback sequences can also be defined and used as a scrambling code.

[186] When scrambling based on a secondary synchronization code (SSC) 1 is applied to SSC2, a combining form such as the aforementioned scrambling based on a primary synchronization code (PSC) + scrambling based on a secondary synchronization code (SSC) 1 can be used.

[187] Inverse-m of the present invention can be used, as discussed above, separately for a scrambling scheme based on a primary synchronization code (PSC), separately for a scrambling scheme based on a secondary synchronization code (SSC) 1, or one of two scrambling schemes, or both of the two scrambling schemes.

[188]

[189] VIII. Cell search

[190] Cell search is the procedure by which a user equipment (UE) obtains time and frequency synchronization with a cell and determines a cell identifier. Typically, a cell search is classified into an initial cell search, which is performed initially, after the user equipment (UE) is turned on, and an initial cell search that performs a handover or measurement of a neighboring cell.

[191] The cell search uses a primary synchronization signal (PSS) and a secondary synchronization signal (SSS). The primary synchronization signal (PSS) is used before receiving slot synchronization (or frequency synchronization) and a unique identifier. Secondary Synchronization Signal (SSS) is used before frame synchronization and cell identification group. The cell identifier for said cell is adopted by a unique identifier in said cell identification group.

[192] FIG. 19 is a diagram showing a cell search procedure in accordance with an embodiment of the present invention.

[193] Referring to FIG. 19, a user equipment (UE) searches for a primary synchronization signal (PSS) (step S310). A user equipment (UE) identifies a primary synchronization code (PSC) by a primary synchronization signal (PSS) transmitted from a base station. Slot synchronization is received using the primary synchronization signal (PSS). Frequency synchronization can also be received using said primary synchronization signal (PSS). The primary synchronization code (PSC) in the primary synchronization signal (PSS) is associated with a unique identifier. When there are 3 unique identifiers, each of the 3 primary synchronization codes (PSCs) is displayed one-to-one for each of the unique identifiers.

[194] Next, the user equipment (UE) searches for a secondary synchronization signal (SSS) (step S320). A user equipment (UE) identifies two Secondary Synchronization Codes (SSCs) by a Secondary Synchronization Signal (SSS) transmitted from said base station. Frame synchronization is adopted using a secondary synchronization signal (SSS). The secondary synchronization signal (SSS) is mapped to the cell identification group. Using the secondary synchronization signal (SSS) and the primary synchronization signal (PSS), a cell identifier is received. For example, it is assumed that there are 504 unique cell identifiers, said cell identifiers are grouped into 168 unique cell identification groups, and each group contains three unique identifiers. 3 primary synchronization signals (PSS) are respectively mapped to three unique identifiers, and 168 secondary synchronization signals (SSS) are respectively mapped to 168 cell identification groups. The Icell cell identifier can thus be uniquely determined by an Igr number in the range of 0 to 167 representing the cell identification group and an Iu number in the range of 0 to 2 representing a unique identifier in the said cell identification group, as shown by Icell = 3Igr + Iu.

[195] The secondary synchronization signal (SSS) includes two secondary synchronization codes (SSC). Each secondary synchronization code (SSC) is scrambled using different scrambling codes. Said scrambling code is associated with a primary synchronization code (PSC) included in a primary synchronization signal (PSS). Therefore, a cell search can be performed much faster by reducing the interference of a neighboring cell and by improving the secondary synchronization signal (SSS) detection characteristics.

[196] Secondary synchronization signal (SSS) signal determination characteristics can be improved by scrambling two secondary synchronization codes (SSC) in the secondary synchronization signal (SSS) using various scrambling codes. Cell search can be performed more reliably and can be prevented from delaying. In addition, with an increase in the number of available sequences, the amount of information transmitted by the synchronization signals and the throughput of the user equipment (UE) can be increased.

[197] Although synchronization signals have been discussed above, the technical features of the present invention can be applied to other signals that deliver information in order to improve channel detection performance. For example, this may apply to an uplink / downlink reference signal, an acknowledgment signal (ACK) / non-acknowledgment signal (NACK), a random access preamble, etc.

[198] All of the functions discussed above can be performed by a processor, such as a microprocessor, controller, microcontroller, and application specific integrated circuit (ASIC) in accordance with the software code or program code for performing the above functions. The program code can be developed, made and implemented based on the descriptions of the present invention, and this is well known to specialists in this field of technology.

[199] While the present invention has been shown and discussed in detail with reference to its exemplary embodiments, it will be appreciated by those skilled in the art that various changes in form and detail can be made here without departing from the mentioned idea and scope actions of the present invention, as defined by the attached claims. Exemplary embodiments should be considered only in a descriptive sense and not for purposes of limitation. Therefore, the scope of the present invention is determined not by a detailed description of the present invention, but by the appended claims, and all differences in the mentioned area will be construed as being included in the present invention.

Claims (15)

1. A method of performing a cell search in a wireless communication system, carried out by user equipment and comprising:
search for a primary synchronization signal (PSS) containing a primary synchronization code (PSC); and
searching for a secondary synchronization signal (SSS) containing the first secondary synchronization code (SSC) and the second secondary synchronization code (SSC) after searching for the primary synchronization signal,
wherein the first secondary synchronization code (SSC) and the second secondary synchronization code (SSC) are respectively scrambled by using the first scrambling code and the second scrambling code, and said first scrambling code and said second scrambling code are associated with the primary synchronization code (PSC). 2. The method according to claim 1, in which the first secondary synchronization code (SSC) and the second secondary synchronization code (SSC) are determined by two different cyclic shifts of the m-sequence generated by the generating polynomial x ⁵ + x ² +1. 3. The method according to claim 1, in which the first scrambling code and the second scrambling code are determined by two different cyclic shifts of the m-sequence generated by the generating polynomial x ⁵ + x ³ +1. 4. The method according to claim 3, in which the cyclic shifts for the first scrambling code and the second scrambling code depend on the unique identifier of the primary synchronization code (PSC). 5. The method according to claim 1, wherein receiving the secondary synchronization signal (SSS) comprises receiving a first secondary synchronization signal (SSS) and receiving a second secondary synchronization signal (SSS),
wherein the first secondary synchronization code (SSC) of the first secondary synchronization signal (SSS) is scrambled by using the first scrambling code, the second secondary synchronization code (SSC) of the first secondary synchronization signal (SSS) is scrambled by using the second scrambling code, the first secondary synchronization code (SSC) a second secondary synchronization signal (SSS) is scrambled using the second scrambling code and a second secondary synchronization code (SSC) of the second secondary synchronization signal (SSS) Lit by using the first scrambling code. 6. The method according to claim 1, in which the primary synchronization signal (PSS) and the secondary synchronization signal (SSS) are received in consecutive symbols with orthogonal frequency division multiplexing (OFDM). 7. The method according to claim 1, in which two secondary synchronization codes (SSC) of the secondary synchronization signal (SSS) are mapped to interleaved subcarriers. 8. A method for transmitting synchronization signals in a wireless communication system, carried out by a base station and comprising:
transmitting a primary synchronization signal (PSS) comprising a primary synchronization code (PSC); and
transmitting a first secondary synchronization signal (SSS) comprising a first secondary synchronization code (SSC) and a second secondary synchronization code (SSC),
wherein the first secondary synchronization code (SSC) is scrambled by using the first scrambling code, and the second secondary synchronization code (SSC) is scrambled by using the second scrambling code,
wherein the first scrambling code and the second scrambling code are associated with a primary synchronization code (PSC). 9. The method of claim 8, in which the first scrambling code and the second scrambling code are determined by two different cyclic shifts of the m-sequence generated by the polynomial x ⁵ + x ³ +1. 10. The method according to claim 9, in which the cyclic shifts for the first scrambling code and the second scrambling code depend on the unique identifier from the primary synchronization code (PSC). 11. The method of claim 8, further comprising:
transmitting a second secondary synchronization signal (SSS) comprising a first secondary synchronization code (SSC) and a second secondary synchronization code (SSC), wherein the first secondary synchronization code (SSC) of the second secondary synchronization signal (SSS) is scrambled using the second scrambling code, and the second the secondary synchronization code (SSC) of the second secondary synchronization signal (SSS) is scrambled using the first scrambling code. 12. User equipment configured to perform a cell search in a wireless communication system, wherein the user equipment is configured to
search for a primary synchronization signal (PSS) containing a primary synchronization code (PSC); and
searching for a secondary synchronization signal (SSS) comprising a first secondary synchronization code (SSC) and a second secondary synchronization code (SSC) after searching for the primary synchronization signal; and
wherein the first secondary synchronization code (SSC) and the second secondary synchronization code (SSC) are respectively scrambled by using the first scrambling code and the second scrambling code, and said first scrambling code and said second scrambling code are associated with the primary synchronization code (PSC). 13. The user equipment of claim 12, wherein the first scrambling code and the second scrambling code are determined by two different cyclic shifts of the m-sequence generated by the generating polynomial x ⁵ + x ³ +1. 14. The user equipment according to item 13, in which the cyclic shifts for the first scrambling code and the second scrambling code depend on the unique identifier from the primary synchronization code (PSC). 15. The user equipment of claim 12, wherein the secondary synchronization signal (SSS) comprises a first secondary synchronization signal (SSS) and a second secondary synchronization signal (SSS), and
wherein the first secondary synchronization code (SSC) of the first secondary synchronization signal (SSS) is scrambled using the first scrambling code, the second secondary synchronization code (SSC) of the first secondary synchronization signal (SSS) is scrambled by using the second scrambling code, the first secondary synchronization code (SSC ) the second secondary synchronization signal (SSS) is scrambled using the second scrambling code, and the second secondary synchronization code (SSC) of the second secondary synchronization signal (SSS) is scrambled mblyuyut using the first scrambling code.

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