KR100629680B1 - Apparatus and method for off-line cell search in asynchronous CDMA communication system - Google Patents

Abstract

The present invention relates to an apparatus and method for searching for a cell of a terminal in a mobile communication system. In particular, the present invention relates to offline and then offline data buffering during a TG interval that occurs for interfrequency handover in an asynchronous CDMA communication system. The present invention relates to a high speed offline cell search apparatus and method for performing a data buffering inputted in a and pre-generating a scrambling code in order to extend an available search interval to correlate the input data with the scrambling code. According to an aspect of the present invention, there is provided a cell search apparatus of a mobile communication system for high-speed cell searching in an offline state, the apparatus comprising: a control unit for generating a control signal for performing offline cell search; A scrambling code generation unit for generating a predetermined number of scrambling codes according to a control signal of the controller; A storage unit to store received data according to a control signal of the controller; And a correlator for correlating received data of the storage unit with the scrambling code of the scrambling code generation unit according to a control signal of the controller.

Asynchronous CDMA Communication System, Offline Cell Search, Scrambling Code Pre-Generation

Description

Apparatus and method for off-line cell search in asynchronous CDMA communication system in asynchronous code division multiple access communication system             

1 is a diagram illustrating an interfrequency handover in a mobile communication system.

 2 illustrates a compressed mode in an asynchronous code division multiple access (CDMA) communication system.

3 illustrates an online / offline cell search apparatus according to an embodiment of the present invention.

FIG. 4 is a diagram illustrating phase-related timing of a scrambling code for correlating a received signal storage time for offline search according to an embodiment of the present invention.

5 is a flowchart illustrating a mask offset selection process in offline cell search of an asynchronous CDMA communication system according to an embodiment of the present invention.

6 is a flowchart illustrating an offline cell search process in an asynchronous CDMA communication system according to an embodiment of the present invention.

FIG. 7 illustrates a frame boundary according to a window searching method according to an embodiment of the present invention. FIG.

8A illustrates a phase between a stored signal and a scrambling code for offline window search in an asynchronous CDMA system according to an embodiment of the present invention.

8B illustrates a phase between a stored signal and a scrambling code for offline window search in an asynchronous CDMA system according to an embodiment of the present invention.

8C illustrates a phase between a stored signal and a scrambling code for offline window search in an asynchronous CDMA system according to an embodiment of the present invention.

8D illustrates a phase between a stored signal and a scrambling code for offline window search in an asynchronous CDMA system according to an embodiment of the present invention.

9 is a flowchart illustrating a mask offset selection process in offline window search of an asynchronous CDMA communication system according to an embodiment of the present invention.

10 is a flowchart illustrating an offline window searching process according to an embodiment of the present invention.

11 is a view showing the location of data used for data storage and correlation in a transmission gap (TG) according to an embodiment of the present invention.

FIG. 12 is a diagram illustrating an online / offline cell search apparatus according to another embodiment of the present invention, wherein a number of scrambling code pre-generations is set.

FIG. 13 illustrates an online / offline cell search apparatus according to another embodiment of the present invention.

FIG. 14 is a view showing the location of data used for data storage and correlation in a transmission gap according to another embodiment of the present invention. FIG.

FIG. 15A illustrates a phase of a scrambling code for correlation with a reception time of a received signal in offline cell search according to another embodiment of the present invention.

FIG. 15B is a diagram illustrating a phase of a scrambling code for correlation with a reception time of a received signal in offline cell search according to another embodiment of the present invention. FIG.

 16 is a flowchart illustrating a mask offset selection process in an offline search of an asynchronous CDMA communication system according to another embodiment of the present invention.

17 is a flowchart illustrating an offline cell search process in an asynchronous CDMA communication system according to another embodiment of the present invention.

18A illustrates a phase between a stored signal and a scrambling code for offline window searching according to another embodiment of the present invention.

18B illustrates a phase between a stored signal and a scrambling code for offline window searching according to another embodiment of the present invention.

18C illustrates a phase between a stored signal and a scrambling code for offline window searching according to another embodiment of the present invention.

18D illustrates a phase between a stored signal and a scrambling code for offline window searching according to another embodiment of the present invention.

19 is a flowchart illustrating a mask offset and pre-generated number selection process for offline window search in an asynchronous CDMA communication system according to another embodiment of the present invention.

20 is a flowchart illustrating an offline window searching process of checking a phase around a frame boundary of a target cell according to another embodiment of the present invention.

The present invention relates to an apparatus and method for searching for a cell of a terminal in a mobile communication system. In particular, the present invention relates to offline and then offline data buffering during a TG interval that occurs for interfrequency handover in an asynchronous CDMA communication system. The present invention relates to a high speed offline cell search apparatus and method for performing a data buffering inputted in a and pre-generating a scrambling code in order to extend an available search interval to correlate the input data with the scrambling code.

1 is a diagram illustrating an interfrequency handover in a mobile communication system.

When a mobile station in a busy state moves out of its cell boundary and moves to an adjacent base station service area, the terminal automatically tunes to a new call channel of the neighboring base station so that the call is continuously maintained. (handover)

In particular, the UE must perform an inter-frequency handover in order to move from a serving cell currently being served to a cell using a different frequency.

In general, a mobile station (MS) operating in a code division multiple access (CDMA) system, for example, an IS-95 code division multiple access system, is a mobile communication system. An initial cell search is performed to obtain pseudo noise (PN) code timing at power on.

The pseudonoise code is transmitted to all mobile stations in the base station via a forward pilot channel. The forward pilot channel is a channel in which unmodulated data is spread using a pseudo noise code, and all mobile stations operating within a cell area of a specific base station obtain the pseudo noise code timing using the forward pilot channel.

All base stations constituting the IS-95 code division multiple access system are mutually synchronized by Global Positioning System (GPS) satellites, and each of the base stations uses the same pseudonoise code. The base stations are distinguished from each other by giving different pseudonoise code offsets to the base stations.

Therefore, the mobile station operating in the IS-95 code division multiple access system performs initial cell search by obtaining the pseudo-noise code timing of the base station to which the mobile station belongs from the forward pilot channel at power-on.

The process of performing the initial cell search using the received pseudonoise code at the mobile station receiver is a general correlation process. First, the mobile station receiver performs correlation while moving the search window equal to the pseudonoise code length.

The search is performed until the maximum correlation value is obtained, and cell division is performed by obtaining a pseudonoise code phase having the maximum correlation value.

The IS-95 code division multiple access system has evolved into a next generation communication system, and one of the next generation communication systems is a UMTS (Universal Mobile Telecommunication System). The UMTS system also uses a code division multiple access scheme, but is an asynchronous system that performs asynchronous operation between base stations.

A mobile station operating in the UMTS system (UE: User Element, same concept as a mobile station (MS) in the IS-95 code division multiple access system) is also an initial cell as in a mobile station operating in the IS-95 code division multiple access communication system. Perform a search.

Here, the IS-95 code division multiple access system and the UMTS are the same in that they use a code division multiple access scheme, but the IS-95 code division multiple access system is a synchronous system and the UMTS is an asynchronous system and the initial cell. There is a difference in the search operation.

The cell search operation of the UMTS is as follows.

First, a cell specific code for distinguishing each of the base stations is assigned to each of the base stations Node B constituting the UMTS, and the UMTS is configured with the assigned cell distinguishing code. Identify each base station.

For example, if there are 512 cells constituting the UMTS, and there is one base station for each cell, there are 512 base stations constituting the UMTS. In this case, different cell identification codes are assigned to each of the 512 base stations, and each of the base stations configuring the UMTS is identified using a cell identification code assigned to each of the 512 base stations.

In this case, the mobile station must search for each of the 512 base stations constituting the UMTS in order to search for the base station to which it belongs.

Since the mobile station searches for each of the 512 base stations constituting the UMTS, the mobile station checks each phase of the code constituting the cell identification code of each of the 512 base stations. Searching takes a lot of time.

Since it is inefficient to use a general cell search algorithm having the highest correlation energy value, a multi-step cell search algorithm is implemented to overcome this problem.

For example, 512 base stations are classified into a predetermined number of groups, for example, 64 groups. Each of the 64 groups is assigned a different group identification code to distinguish a base station group, and each of the 8 base stations belonging to one group uses a spreading code (scrambling code) used for a specific channel (CPICH: Common Pilot Channel). Use to distinguish.

That is, the mobile station first obtains a base station group, and correlates the CPICH with the scrambling codes for the obtained base station group to identify the base station.

Meanwhile, the UMTS proposes a Site Selection Diversity Transmit (SSDT) technique used in a soft handover mode. Site, base station and cell have the same meaning as each other.

SSDT is an optional large-scale diversity scheme in soft handover mode, whose service is determined by the system side. Through the SSDT operation, the user side selects one cell called "Primary cell" among the cells in the active group.

At this time, all other cells that are not selected become "Non-primary cell". The purpose of the SSDT is to reduce the interference caused by multiplexing in soft handover mode by performing information transmission in downlink in a first priority cell (hereinafter referred to as a primary cell).

Temporary identification is assigned to each of the valid cells whose transmission level is above a predetermined level for the primary cell selection.

The UE (UE) periodically measures and compares reception levels of common pilots transmitted from valid cells, and selects a cell having the largest pilot power as the primary cell. Thereafter, the transmission powers of the cells selected in the lower order by the UE are cut off.

The temporary identifier of the primary cell is used as a site selection signal, and is assigned to a binary bit sequence having a specific bit length based on the Hadamard code. Here, the performance of the cell identification code is determined by the maximum autocorrelation function, the maximum cross-correlation function value or the minimum hamming distance.

Therefore, there is a need for an optimal cell identification code having a maximum autocorrelation value, a small maximum cross correlation value, or a minimum hamming distance.

2 is a diagram illustrating a compressed mode in an asynchronous code division multiple access (CDMA) communication system.

 Universal Mobile Telecommunications System (UMTS), an asynchronous code division multiple access (CDMA) communication system, supports a compressed mode for inter-frequency handover to base stations using different frequency bands. do.

When the compressed mode is started in the UMTS, the base station generates a transmisstion gap (TG) in a dedicated physical channel (DPCH) as shown in FIG. 2. The UE performs cell search for UMTS cells using different frequency bands during the TG interval for interfrequency handover.

The length of the TG defined in the 3GPP (Third Generation Partnership Project) is 3, 4, 5, 7, 10, and 14 slots when one frame is 10 ms and one slot is 10/15 ms.

On the other hand, in the prior art, by directly processing the signal input to the modem during the TG period on-line, even if the TG interval is too short or complete even if the cell search is completed, the correlation length required for the cell search is limited, resulting in poor cell search performance. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and when performing correlation within a limited time such as a transmission gap (TG) interval, the offline scrambling code generation unit is initialized and stored with a phase corresponding to the first available data. An object of the present invention is to enable scrambling code generation from an arbitrary phase in offline window search.

According to an aspect of the present invention, there is provided a cell searching apparatus of a mobile communication system for high-speed cell searching in an offline state, the apparatus comprising: a control unit for generating a control signal for performing offline cell searching; A scrambling code generation unit for generating a predetermined number of scrambling codes according to a control signal of the controller; A storage unit to store received data according to a control signal of the controller; And a correlator for correlating received data of the storage unit with the scrambling code of the scrambling code generation unit according to a control signal of the controller.

In the cell search apparatus of the mobile communication system for high-speed cell search offline, the control unit is characterized in that for setting the number of pre-generated, initial conditions, masking value, masking offset of the scrambling code generation unit.

In the cell search apparatus of the mobile communication system for high-speed cell search in the offline, the control unit is characterized in that for setting the write start time, the size of the stored data, the read start position of the storage.

Another embodiment of the present invention for achieving the above object is, in the cell search apparatus of the mobile communication system for performing a window search for high-speed cell search in the offline, the control unit for generating a control signal for performing the offline cell search ; A scrambling code generator for generating a scrambling code in advance according to a pre-generated control signal of the controller; A scrambling code state storage unit capable of storing a scrambling code generation state of the scrambling code generation unit; A storage unit for storing the received signal according to the storage control signal of the controller; And a correlation unit that correlates data of the storage unit with the scrambling code of the scrambling code generation unit according to the correlation control signal of the controller.

In the cell search apparatus of a mobile communication system for performing a window search for a high-speed cell search offline, the control unit is characterized in that for setting the number of pre-generated, initial conditions, masking value, masking offset of the scrambling code generation unit .

In the cell search apparatus of a mobile communication system for performing a window search for a high-speed cell search offline, the control unit is characterized in that for setting the write start time, the size of the stored data, the read start position of the storage.

According to still another aspect of the present invention, there is provided a cell search method of a mobile communication system for high speed cell search in an offline state, the method comprising: storing received data in a storage unit; Initializing a scrambling code generator; Generating a scrambling code in advance according to a predetermined number of times; And correlating the received data of the storage unit with the scrambling code at the same time.

According to still another aspect of the present invention, there is provided a cell search method of a mobile communication system for performing a window search for a high speed cell search offline, the method comprising: storing received data in a storage unit; Initializing a scrambling code generator; Generating a scrambling code in advance according to a predetermined number of times; Storing a current state of the scrambling code generator; And performing window correlation on the received data of the storage unit and the scrambling code.

DETAILED DESCRIPTION A detailed description of preferred embodiments of the present invention will now be described with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are used as much as possible even if displayed on different drawings. In addition, in the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, the terms to be described below are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of the user or chip designer, and the definitions should be made based on the contents throughout the present specification.

3 is a diagram illustrating an online / offline cell search apparatus according to an embodiment of the present invention.

As described above, the UE performs cell search for UMTS cells using different frequency bands during the TG interval for interfrequency handover. However, the cell search performance is degraded because the length of the section is too short to complete the cell search during the limited TG period or the correlation length required for the cell search is limited even upon completion.

An embodiment of the present invention buffers the cell search data received from the base station in the storage unit 102 during the limited TG period, and performs the cell search in an offline state. The multiplexer (MUX) 100 provides the received data (signal) to the correlator 104, and provides the correlated part 104 with data buffered in the storage 102 for offline search.

The scrambling code generation unit 106 receives a scrambling code initial condition and a masking value of the target cell from the control unit, where the masking value enables the scrambling code to be generated from a predetermined specific phase other than zero. Play a role.

If the masking value is used as a value corresponding to an arbitrary phase, the scrambling code generator 106 generates the scrambling code from the phase.

Masking values should be stored in advance, and a total of N masking values are stored by dividing the phase of the scrambling code at specific intervals. For example, in the case of UMTS, the scrambling code has a length of 38400 chips and a masking value stores N pieces (N = 38400 / M) in M chip units. If the masking value is not used, the scrambling code is always generated from the frame boundary (scrambling code phase 0).

The correlator 104 correlates the scrambling code with the received signal and then transmits a correlation result to the controller 108.

On the other hand, in order to correlate the cell searcher, data used for correlation of the cell search must also be input in accordance with the phase of the scrambling code to be initialized.

For example, when the scrambling code is initialized to the phase of 'nx M ' (where n = 0, 1,, N-1), the received signal used for correlation is also MASK_OFFSET, from the frame boundary assumed for the target cell. That is, the received signal at a time point separated by nxM chip is input to the correlation unit.

In the case of the offline search, a received signal of a certain size is stored from the start point of writing to the storage unit, and when the storing is completed, the received signal is inputted to the correlator from the data of the read start position.

At this time, the read start position should be determined such that the data inputted to the correlator is a position that is separated by a multiple of OFFSET from the frame boundary assumed for the target cell in accordance with the phase of the initialized scrambling code.

FIG. 4 is a diagram illustrating phase-related timing of a scrambling code for correlation with a reception signal storage time for offline search according to an embodiment of the present invention.

 In FIG. 4, when a reference count is initialized at an instant and repeated with a scrambling code length (frame length), an arbitrary time point may be expressed as a specific value of a reference count based on an absolute reference count. The phase difference of different cells may be represented by the difference between the reference count values at the frame boundary of each cell.

 When NxM = scrambling code length, the reference count can be expressed by dividing the reference count by 1 for every M chip and the chip count by 1 for every 1 chip. M count is 0, 1,... , N-1, and chip count is 0, 1,... , Has a value of M-1.

Hereinafter, an arbitrary time point will be expressed as (M count, chip count).

It is assumed that the buffering time point of the received signal is (3, B) and the frame boundary (FB) position of the scrambling code of the cell to be examined is (2, A).

Assume that BUF_START_M represents M count at the position where buffering has started, and FRAME_SYNC_M represents M count at a frame boundary. When the mask value is stored in M chip units, the mask value to be applied to the scrambling code generation unit is selected as follows. (In FIG. 4, the first code generated in the scrambling code generation unit to which the mask is applied becomes MASK_OFFSET * M th chip. will be.)

(a) When chip count B at the start of buffering is less than or equal to chip count A at the frame boundary position, a mask value corresponding to '(BUF_START_M-FRAME_SYNC_M) modulo N'-th MASK_OFFSET is used.

(b) Otherwise, a mask value corresponding to '(BUF_START_M + 1-FRAME_SYNC_M) modulo N' MASK_OFFSET is used.

5 is a flowchart illustrating a mask offset selection process in offline cell search of an asynchronous CDMA communication system according to an embodiment of the present invention.

As described above, when chip count B at the start of buffering is equal to or smaller than chip count A at the frame boundary position, a mask value corresponding to '(BUF_START_M-FRAME_SYNC_M) modulo N'-th MASK_OFFSET is used.

If the chip count B at the start of buffering is larger than the chip count A at the frame boundary position, a mask value corresponding to '(BUF_START_M + 1-FRAME_SYNC_M) modulo N' MASK_OFFSET is used.

According to a correlation command from the controller, data corresponding to a masking offset from a frame boundary is input to the correlation unit, and the scrambling code generator generates a scrambling code having a masking offset. The correlation unit receives the two signals and performs correlation according to the parameter set in the controller, and reports the result to the controller.

6 is a flowchart illustrating an offline cell search process in an asynchronous CDMA communication system according to an embodiment of the present invention.

When the control unit determines the reading time of the reception signal, the writing start time and the size of the data to be stored (S100), the storage unit receives the cell search reception data (signal) from the base station of the predetermined size at the storage time of the reception signal according to the command of the control unit. Save (S102).

The scrambling code generator determines a search-related parameter and a read position according to a command of the controller to set a correlation range (S104).

The controller assigns a masking value and a masking offset to the scrambling code generator, loads an initial condition of the scrambling code generator, and initializes a phase (S106). As described above, the scrambling code is generated by being delayed by a masking value.

The correlation unit receives the scrambling code and the received signal stored in the storage unit through the multiplexer and then performs their correlation (S108).

FIG. 7 illustrates a frame boundary according to a window searching method according to an embodiment of the present invention.

The window search method is one of cell search methods for a multipath environment and checks a phase around a frame boundary of a target cell.

 For example, as shown in FIG. 7, the correlation of the phase of the total W chip interval from the X chip space away from the negative direction around the frame boundary point of the target cell may be performed to investigate whether the frame boundary exists.

The number of phases that can be checked simultaneously by the correlator in window searching may vary depending on the capabilities of the terminal. If it is assumed that the correlator can simultaneously correlate the S chip intervals, the correlator correlates the scrambling codes with the received signals of S different phases having a phase difference of 1 chip each, or 1 chip each with the received signal of the same phase. The S scrambling codes with phase difference are correlated. The present invention is explained by taking the former case as an example, and the latter case is also applicable.

In the window search to correlate the S chip intervals at the same time, the inspection for the W chip interval is repeated W / S times by S chip. The total window size W will then be a multiple of S. For example, if W = 64 and S = 2, the correlation unit correlates the phases for 2 chip sections at a time, then checks the 2 chip sections again with the phase delayed by 2 chips, and repeats 32 times in this way. Correlation is performed for the phase of a total of 64 chips.

8A, 8B, 8C, and 8D illustrate phases between a stored signal and a scrambling code for offline window search in an asynchronous CDMA system according to an embodiment of the present invention.

In order to perform the window search in the offline search, the phase of the data stored in the initial correlation and the phase of the scrambling code must have a phase difference of X chip.

8A, 8B, 8C, and 8D, the M count of the assumed frame boundary of the target cell is 2, the chip count is A (2, A), and the write start position of the storage unit is (3, B). lets do it.

(a) If A is greater than or equal to 'B + X' and 'B + X' is less than M, then MASK_OFFSET = (BUF_START_M-FRAME_SYNC_M) modulo N = 3-2 = 1 slot.

(b) If A is greater than or equal to 'B + X' and 'B + X' is greater than or equal to M, determine MASK_OFFSET = (BUF_START_M + 1-FRAME_SYNC_M) modulo N = 3 + 1-2 = 2.

(c) If A is less than 'B + X' and 'B + X' is less than M, determine MASK_OFFSET = (BUF_START_M + 1-FRAME_SYNC_M) modulo N = 3 + 1-2 = 2.

(d) If A is less than 'B + X' and 'B + X' is greater than or equal to M, determine MASK_OFFSET = (BUF_START_M + 2-FRAME_SYNC_M) modulo N = 3 + 2-2 = 3.

9 is a flowchart illustrating a mask offset selection process in offline window search of an asynchronous CDMA communication system according to an embodiment of the present invention.

As described above, if A is greater than or equal to 'B + X' and 'B + X' is less than M, it is determined by MASK_OFFSET = (BUF_START_M-FRAME_SYNC_M) modulo N.

If A is greater than or equal to 'B + X' and 'B + X' is greater than or equal to M, determine MASK_OFFSET = (BUF_START_M + 1-FRAME_SYNC_M) modulo N.

If A is less than 'B + X' and 'B + X' is less than M, MASK_OFFSET = (BUF_START_M + 1-FRAME_SYNC_M) modulo N.

If A is less than 'B + X' and 'B + X' is greater than or equal to M, MASK_OFFSET = (BUF_START_M + 2-FRAME_SYNC_M) modulo N.

When the correlation part completes the S chip phase, the reading start position of the data inputted from the stored data to the correlation part increases by S chip, and the scrambling code generator reloads the initial condition again and generates the scrambling code. At this time, the checked phase is assumed to be 'frame boundary point-X + S' to 'frame boundary point-X + 2S-1'. In this way, when all correlations for the W chip interval are completed, the correlation result is reported to the controller.

10 is a flowchart illustrating a process of searching for an offline window in an embodiment of the present invention.

When the controller determines the reading time, the writing start time, and the size of the data to be stored (S200), the storage unit stores the received data (signal) having a predetermined size at the time of storing the received signal according to the command of the controller (S202).

The scrambling code generator determines a search-related parameter and a read position according to a command of the controller to set a correlation range (S204).

The controller assigns a masking value and a mask offset to the scrambling code generator, loads an initial condition of the scrambling code generator, and initializes a phase (S206). As described above, the scrambling code is generated by being delayed by a masking value.

The correlation unit receives the scrambling code and the received data (signal) stored in the storage unit through the multiplexer and then performs their window correlation (S208).

In this case, the present invention can be seen that the position that can actually be used for correlation in the stored received data is limited.

FIG. 11 is a diagram illustrating a location of data used for data storage and correlation in a transmission gap (TG) according to an embodiment of the present invention.

For off-line discovery of interfrequency cells, the phase of the cell scrambling code examined in the transmission gap (TG) corresponds to the correlation length from {(N-1) X MASK_OFFSET}, which is a multiple of MASK_OFFSET. The received signal, that is, data to be used for correlation, must be input to the offline searcher. Therefore, the reception signal storage must start writing at least before this time point, and store data having a correlation length or more.

Meanwhile, since the time T_proc for the preparation period for shifting the frequency is required in the TG section, the reception signal storage for the actual offline search is possible after the T_proc.

Therefore, the farther the point where the phase of the target cell scrambling code becomes a multiple of MASK_OFFSET from the TG start point, the shorter the period actually available in the TG. At this time, the correlation length for cell search should be reduced according to the available interval.

FIG. 12 is a diagram illustrating a case in which an on-line / offline cell search apparatus according to another embodiment of the present invention is set in the number of scrambling code pre-generations.

The storage unit 202 receives a write start time and a data size to be stored from the controller, stores the received signal, receives a read start position from the controller, and sequentially multiplexes the data from the corresponding position among the stored data (MUX: 200). It passes to the correlation unit 204 through.

The correlator 204 directly receives the received signal in the case of the online search, and correlates with the scrambling code from the scrambling code generator 206 by receiving the signal input from the storage 202 in the case of the offline search. The result is reported to the control unit 208.

At this time, the signal input to the correlator 204 is selected by the controller 208 according to whether it is an on-line search or an off-line search.

The scrambling code generation unit 206 is initialized by receiving a pre-generation number, an initial condition, a masking value, and a masking offset from the control unit 208.

Here, the number of pre-generations refers to the number of times that the scrambling code generation unit 206 is initialized by receiving an initial condition, a masking value, and a masking offset, and then generates a scrambling code in advance before correlation is started. .

This indicates that the scrambling code generation unit 206 can be initialized to any phase other than a specific masking offset unit.

When the generation of the scrambling code for the number of pre-generated times is completed, the scrambling code generation unit 206 generates a scrambling code for every chip from the start of the correlation according to the command of the control unit 208.

The controller 208 initializes the scrambling code, controls the write and read operations of the storage unit 202, controls the correlation operation of the correlation unit 204, and selects a signal input to the correlation unit 204. Do it.

FIG. 13 illustrates an online / offline cell search apparatus according to another embodiment of the present invention.

On the other hand, the on-line / offline cell search apparatus according to another embodiment of the present invention is characterized in that the number of scrambling code pre-generation is set, and comprises a separate scrambling code generator state storage unit 206 do.

The storage unit 202 receives a write start time and a data size to be stored from the controller, stores the received data (signal), receives a read start position from the controller, and sequentially multiplexes the data from the corresponding position among the stored data. MUX) through the 200 to the correlator 204.

The correlator 204 receives the received data (signal) directly in the case of the online search, and the scrambling from the scrambling code generator 206 in response to the data (signal) input from the storage 202 in the case of the offline search. Correlate with the code and report the result to the controller 208.

At this time, the data (signal) input to the correlator 204 is selected by the controller 208 according to whether it is an online search or an offline search.

The scrambling code generation unit 206 is initialized by receiving a pre-generation number, an initial condition, a masking value, and a masking offset from the control unit 208.

As described above, the pre-generation number is initialized by the scrambling code generation unit 206 receiving an initial condition, a masking value, and a masking offset, and then generating the scrambling code in advance before correlation is started. The set number of times.

Accordingly, the scrambling code generator 206 may be initialized to an arbitrary phase in addition to a specific masking offset unit.

When the generation of the scrambling code for the number of pre-generated times is completed, the scrambling code generation unit 206 generates a scrambling code for every chip from the start of the correlation according to the command of the control unit 208.

Meanwhile, the scrambling code generator state storage unit 206 stores the state of the scrambling code generator.

The state of the scrambling code generation unit refers to a state in which the pre-generation of the scrambling code is completed according to the number of pre-generations set by the controller after the scrambling code initialization.

The controller 208 initializes the scrambling code, controls the write and read operations of the storage unit 202, controls the correlation operation of the correlation unit 204, and selects a signal input to the correlation unit 204. Do it.

FIG. 14 is a diagram illustrating a location of data used for data storage and correlation in a transmission gap according to another embodiment of the present invention.

The present invention is characterized by maximizing a section of data available for cell search in a transmission gap section in a compression mode, and performing correlation from the first data among the signals stored in the transmission gap section. do.

As described above, in order to perform an offline search for an interfrequency cell, from the time point {(N-1) X MASK_OFFSET}, the phase of the cell scrambling code checked in the transmission gap (TG) corresponds to a multiple of MASK_OFFSET. The received signal corresponding to the correlation length, that is, data to be used for correlation, must be input to the offline searcher.

Therefore, the reception signal storage must start writing at least before this time point, and store data having a correlation length or more.

On the other hand, since the time T_proc, which is a preparation period for shifting the frequency, is required in the TG section, it is possible to store the received signal for the actual offline search after T_proc.

15A and 15B are diagrams illustrating a phase of a scrambling code for correlation with a reception time of a received signal in offline cell search according to another embodiment of the present invention.

15A and 15B, reference M count indicates an absolute reference of a received signal. When UMTS is targeted, M counts are 0, 1,... , N-1, and A and B, which are the chip counts in the slot, are 0, 1,... , Has a value of M-1.

15A and 15B, it is assumed that the buffering time point of the received signal is (4, B) and the frame boundary position of the scrambling code of the cell to be checked is (2, A). Assume that BUF_START_M represents the M count at the position where buffering has started, and FRAME_SYNC_M represents the M count at the frame boundary.

FIG. 15A illustrates a case where chip count B at the start of buffering is equal to or larger than chip count A at a frame boundary position. At this time, MASK_OFFSET = 'BUF_START_M-FRAME_SYNC_M) modulo N' = 4-2 = 2, and the number of pre-generations is set to P = 'B-A'.

The scrambling code generation unit is initialized by receiving the initial condition, the obtained masking offset and the corresponding masking value from the control unit, and generates the scrambling code in advance as many times as before. When the above operation of the scrambling code generation unit is completed, the first data of the data received in the storage unit is input to the correlation unit, and the correlation unit correlates the scrambling code generated in the scrambling code generation unit with the signal input from the storage unit.

When the correlation starts, the phase of the scrambling code will be M + (B-A) chip. When the correlation operation of the correlation unit according to the parameter set by the control unit is completed, the result is sent to the control unit.

15B illustrates a case where the chip count B at the start of buffering is equal to or larger than the chip count A at the frame boundary position. At this time, MASK_OFFSET = '(BUF_START_M-1-FRAME_SYNC_M) modulo N' = 4-1-2 = 1 is set, and the number of pre-generations is set to P = 'M + B-A'.

The scrambling code generation unit is initialized by receiving the initial condition, the obtained masking offset and the corresponding masking value from the control unit, and generates the scrambling code in advance as many times as before. When the above operation of the scrambling code generation unit is completed, the first data of the data received in the storage unit is input to the correlation unit, and the correlation unit correlates the scrambling code generated in the scrambling code generation unit with the signal input from the storage unit. When the correlation starts, the phase of the scrambling code will be M + (B-A) chip. When the correlation operation of the correlation unit according to the parameter set by the control unit is completed, the result is sent to the control unit.

 16 is a flowchart illustrating a mask offset selection process in an offline search of an asynchronous CDMA communication system according to another embodiment of the present invention.

As described above, the chip count B at the start of buffering is equal to or larger than the chip count A at the frame boundary position. At this time, MASK_OFFSET = 'BUF_START_M-FRAME_SYNC_M) modulo N' = 4-2 = 2, and the number of pre-generations is set to P = 'B-A'.

The chip count B at the start of buffering is equal to or larger than the chip count A at the frame boundary position. At this time, MASK_OFFSET = '(BUF_START_M-1-FRAME_SYNC_M) modulo N' = 4-1-2 = 1 and the number of pre-generations is set to P = 'M + B-A'.

17 is a flowchart illustrating an offline cell search procedure in an asynchronous CDMA communication system according to another embodiment of the present invention.

If the control unit determines the reading time of the reception signal, the writing start time and the size of the data to be stored (S300), the storage unit stores the reception signal having a predetermined size at the reception signal storage time according to the command of the control unit (S302).

The scrambling code generator determines a search related parameter and a read position according to a command of the controller to set a correlation range (S304).

The controller assigns a masking value and a masking offset to the scrambling code generator, loads an initial condition of the scrambling code generator, initializes a phase (S306), and pre-generates a scrambling code (S308). .

The correlation unit receives the scrambling code and the received signal stored in the storage unit through the multiplexer and then performs their correlation (S310).

18A, 18B, 18C, and 18D illustrate phases between a stored signal and a scrambling code for offline window searching according to another embodiment of the present invention.

18A, 18B, 18C, and 18D, the M count of the assumed frame boundary of the target cell is 2, the chip count is A (2, A), and the write start position of the storage unit is (3, B). Assume

18A is a diagram illustrating a case where A <= B and (B-A + X) <M. At this time, the masking offset is set to correspond to BUF_START_M-FRAME_SYNC_M = 4-2 = 2 slots, and the scrambling code is generated in advance by (B-A + X) chip.

18B is a diagram showing the case where A <= B, (B-A + X)> = M. At this time, the masking offset is set to correspond to BUF_START_M + 1- FRAME_SYNC_M = 4 + 1-2 = 3 slots, and the scrambling code is generated in advance by (B-A + X-M) chip.

18C is a diagram showing the case where A> B and (M + B-A + X)> = M. At this time, the masking offset is set to correspond to BUF_START_M-FRAME_SYNC_M = 4-2 = 2 slots, and the scrambling code is generated in advance by (B-A + X) chip.

18D is a diagram illustrating a case where A> B and (M + B-A + X) <M. At this time, the masking offset is set to correspond to BUF_START_M-1-FRAME_SYNC_M = 4-1-2 = 1 slot, and the scrambling code is generated in advance by (M + B-A + X) chip.

19 is a flowchart illustrating a process of selecting a mask offset and a pre-generated number of times for offline window search in an asynchronous CDMA communication system according to another embodiment of the present invention.

As described above, if A <= B, (B-A + X) <M, the masking offset is set to correspond to BUF_START_M-FRAME_SYNC_M, and the scrambling code is generated in advance by (B-A + X) chip.

If A <= B, (B-A + X)> = M, the masking offset is set to correspond to BUF_START_M + 1-FRAME_SYNC_M, and the scrambling code is generated in advance by (B-A + X-M) chip.

If A> B, (M + B-A + X)> = M, the masking offset is set to correspond to BUF_START_M-FRAME_SYNC_M, and the scrambling code is generated in advance as much as (B-A + X) chip.

If A> B, (M + B-A + X) <M, the masking offset is set to BUF_START_M-1-FRAME_SYNC_M, and the scrambling code is generated in advance by (M + B-A + X) chip. .

When the prescrambling generation operation of the scrambling generator is completed, the state of the scrambling code generator, that is, the shift register value is stored.

When the correlation on the S chip phase is completed in the correlator, the position of data input from the stored data to the correlator increases by S chip, and the scrambling code generator reloads the previously stored initial condition and generates a scrambling code. At this time, the checked phase is assumed to be 'frame boundary point-X + S' to 'frame boundary point-X + 2S-1'. In this way, when all correlations for the W chip interval are completed, the correlation result is reported to the controller.

20 is a flowchart illustrating an offline window searching process of checking a phase around a frame boundary of a target cell according to another embodiment of the present invention.

When the controller determines the reading time, the writing start time, and the size of the data to be stored (S400), the storage unit stores the received data (signal) having a predetermined size at the time of storing the received data (signal) according to the command of the controller ( S402).

The scrambling code generator determines a search-related parameter and a read position according to a command of the controller to set a correlation range (S404).

The controller assigns a masking value and a masking offset to the scrambling code generator, loads an initial condition of the scrambling code generator, initializes a phase (S406), and pre-generates a scrambling code (S408). .

When the prescrambling generation operation of the scrambling code generator is completed, the scrambling code generator state storage unit stores the current state of the scrambling code generator, that is, the shift register value (S410).

The correlation unit receives the scrambling code and the received signal stored in the storage unit through the multiplexer and then performs their window correlation (S412). At this time, the correlation unit performs window correlation through the sub-window, and the current state of the stored scrambling code generation unit is reloaded into the scrambling code generation unit as described above every time the sub-window correlation is started.

As a result, the present invention can generate the scrambling code from any phase in the offline search and the offline window search. Accordingly, the present invention can initialize and store a scrambling code generator in a phase corresponding to the first data available when performing correlation within a limited time such as a transmission gap (TG) section of a compressed mode.

The technical spirit of the present invention has been described above with reference to the accompanying drawings, but this is by way of example only and not intended to limit the present invention. In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

As described above, when performing correlation within a limited time, such as a transmission gap (TG) interval, the present invention initializes and stores a scrambling code generator with a phase corresponding to the first available data. The scrambling code can be generated from the phase of.

Claims (10)

A cell search apparatus of a mobile communication system that performs a high speed cell search in an offline manner,  A controller configured to generate a control signal for performing offline cell search; A scrambling code generation unit for generating a predetermined number of scrambling codes according to a control signal of the controller; A storage unit for storing received data for cell search from a base station according to a control signal of the controller; And And a correlator for correlating received data of the storage unit with a scrambling code of the scrambling code generation unit according to a control signal of the controller. The apparatus of claim 1, wherein the controller sets a pre-generated number of times, an initial condition, a masking value, and a masking offset of the scrambling code generation unit. The apparatus of claim 1, wherein the controller sets the write start time, the size of the stored data, and the read start position of the storage unit. A cell search apparatus of a mobile communication system that performs a high speed cell search in an offline manner, A controller configured to generate a control signal for performing offline cell search; A scrambling code generator for generating a scrambling code in advance according to a pre-generated control signal of the controller; A scrambling code state storage unit for storing a scrambling code generation state of the scrambling code generation unit; A storage unit for storing received data for cell search from a base station according to a storage control signal of the controller; And And a correlation unit for correlating data of the received data storage unit with the scrambling code of the scrambling code generation unit according to a correlation control signal of the controller. The apparatus of claim 4, wherein the controller sets a pre-generated number, an initial condition, a masking value, and a masking offset of the scrambling code generator. The apparatus of claim 4, wherein the controller sets a write start time, a size of stored data, and a read start position of the reception data storage unit. 5. The cell search apparatus of claim 4, wherein the correlation unit performs sub window correlation. In the cell search method of the mobile communication system for high-speed cell search in the offline, Storing received data for cell search from a base station in a storage unit; Initializing a scrambling code generator; Generating a scrambling code in advance according to a predetermined number of times; And And simultaneously correlating received data of the storage unit with the scrambling code. In the cell search method of the mobile communication system for high-speed cell search in the offline, Storing received data for cell search from a base station in a storage unit; Initializing a scrambling code generator; Generating a scrambling code in advance according to a predetermined number of times; Storing a current state of the scrambling code generator; And And performing window correlation with respect to the received data of the storage and the scrambling code. 10. The method of claim 9, wherein performing window correlation comprises performing sub window correlation.

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