KR100359494B1 - Apparatus and method for acquiring code group in w-cdma system - Google Patents

Abstract

In the asynchronous W-CDMA system, an apparatus and method for acquiring a code group according to an embodiment of the present invention sums the values of all slots in a code group of a second synchronous channel to be received before performing an operation of determining and acquiring a code group. The number of code groups to be compared can be significantly reduced by using the previously calculated code group group. As a result, the time required for acquiring the code group can be shortened to prevent unnecessary power consumption, thereby prolonging the terminal power life, and supporting fast cell search during handoff. In addition, roaming between heterogeneous networks can be achieved quickly with the same asynchronous W-CDMA system.

Description

Apparatus and method for acquiring code group in asynchronous wideband code division multiple access system {APPARATUS AND METHOD FOR ACQUIRING CODE GROUP IN W-CDMA SYSTEM}

The present invention relates to an apparatus and method for initially acquiring a code received in an asynchronous wideband code division multiple access (hereinafter referred to as " W-CDMA ") system, and more particularly to a synchronization channel for cell search. A device and a method for acquiring a code group in a sync channel).

As a standard specification of the IMT-2000 system which will be commercially available in the next generation mobile communication system, there are asynchronous W-CDMA method promoted by 3GPP and CDMA2000 method which is promoted by 3GPP2.

In the IMT-2000 system, the synchronous method distinguishes base stations by using the same code at the transmitting side or the receiving side, and simply changing the starting point in time. That is, codes obtained by shifting the same code become different codes, and eventually, the reference code becomes one.

On the other hand, the asynchronous W-CDMA system is a system in which each base station uses a different code, and unlike the synchronous, even if the code used in one base station is shifted, the code is not used in another base station. That is, in the asynchronous method, several codes exist as a reference.

1 is a diagram illustrating a structure of a synchronization channel in a wideband code division multiple access scheme which is an asynchronous scheme proposed as a standard.

In the asynchronous W-CDMA system, as shown in FIG. 1, a synchronization channel (SCH) used for cell search is largely divided into a primary synchronization channel indicating a starting point of a slot. It is divided into a second sync channel representing the value of each slot. Here, the slot means a unit configuring a sync channel (including a first sync channel and a second sync channel), and the value of the slot means a value of each slot constituting a second sync channel. In addition, one frame of the synchronization channel has a period of 10 msec, and each slot has 15 slots.

The first synchronous channel searcher (not shown) provided at the receiving end detects the starting point of each slot of the first synchronous channel received and provides information indicating the start position of each slot of the synchronous channel.

The second synchronous channel searcher (not shown) provided at the receiving end recognizes each slot value of the second synchronous channel received using the synchronous channel slot start position information. In this case, the second synchronization channel searcher provides the recognized slot values in code group units, which are groups of slot values corresponding to one frame period of a synchronization channel. That is, the second synchronization channel searcher provides values of a second synchronization code (SCC) of the received second synchronization channel.

A code group obtainer (not shown) provided at the receiving end compares a code group corresponding to one frame period of the received and recognized second synchronization channel with code groups proposed and stored by the standard. The code group obtainer obtains a code group by determining which code group the received and recognized code group corresponds to among the previously stored code groups. That is, the code group of the base station to which it belongs is determined, and a scrambling code for identifying the base station is obtained by using the obtained code group to complete a cell search to which the base station belongs.

However, in the asynchronous W-CDMA system, the conventional code group acquisition method uses each slot value of the code group of the received and recognized second synchronous channel and each slot value of a predetermined number of code groups proposed and stored by the standard. It is an algorithm that judges by comparing with each other.

An example of a conventional code group acquisition method and an average time for acquiring the code group in an asynchronous W-CDMA system are as follows.

The following shows the values of the second synchronization code (SCC) of the second synchronization channel specified in the standard of 3GPP.

The Scrambilng Code Group # 0 to # 63 refers to 64 code groups defined in the standard, and the slot numbers # 0 to # 14 refer to 15 slot numbers included in each code group. As described above, according to the conventional code group acquisition algorithm in the asynchronous W-CDMA system, the average time taken to acquire the code group can be calculated as shown in Equation 1 below.

Here, T denotes a time taken to compare a certain slot value included in the code group of the received second synchronization channel with a certain slot value provided in the code groups proposed and stored by the standard.

Equation 1 is described in more detail as follows.

For example, if the code group of the received second synchronous channel and the previously stored code groups (Group # 0 to Group # 63) are compared with each other (see the figure above), it is assumed that the system starts from Group # 0.

If the code group of the second synchronization channel actually received is Group # 0, the time for comparing the values of each slot (# 0 to # 14) of the code group is 15T. If the code group of the second synchronous channel actually received is Group # 1, the group is compared first from Group # 0 and then Group # 1. Therefore, the time for comparing each slot (# 0 to # 14) of the code group is 15 * 2 * T. In this way, if the code group of the second synchronous channel actually received is Group # 63, the comparison is made sequentially from Group # 0, so that the time for comparing each slot value of the code group is 15 * 64 * T.

Therefore, if all of the comparison time for the code groups of the 64 types of second synchronization channels that can be received are added and divided by 64 again, the conventional average code group acquisition time can be expressed as shown in Equation 1 above. You can see that.

In other words, an example of the time taken to acquire a conventional code group in an asynchronous W-CDMA system can be expressed by Equation 1 above. As a result, the terminal power life may be long, and it may be able to support fast cell search during handoff. Also, with the same asynchronous W-CDMA system, roaming between heterogeneous networks can be achieved quickly.

Accordingly, an object of the present invention is to calculate the sum of the values of each slot in the code group of the second synchronous channel to be received and the previously stored code group before performing the operation of determining and acquiring the code group in the asynchronous W-CDMA system. By using groups, the number of code groups to be compared can be significantly reduced, which reduces the time required to acquire code groups, prevents unnecessary power consumption, prolongs terminal power life, and supports fast cell search during handoff. The present invention provides an apparatus and method for acquiring a code group.

In order to achieve the above object, the present invention provides a first synchronous channel searcher that detects a slot start point of a received first synchronous channel and provides sync channel slot start position information in an asynchronous wide code division multiple access system. ; A second synchronous channel searcher for recognizing each slot value of a received second synchronous channel in units of a code group of one frame period using the synchronization channel slot start position information; A summer for summing slot values of the recognized code group units; A selector for selecting a pre-stored code group group corresponding to the sum of the slot values for each code group unit; And a code group obtainer for obtaining a code group by comparing the code group corresponding to the corresponding code group group with the code group of the received second synchronization channel.

In addition, the present invention provides a method of obtaining a code group in an asynchronous wide area code division multiple access system, comprising: a first step of detecting starting slots of received first synchronization channels and providing synchronization channel slot starting position information; A second step of recognizing each slot value of a received second synchronization channel in units of code groups of one frame period by using the synchronization channel slot start position information; A third step of summing each slot value for each recognized code group unit; A fourth step of selecting a pre-stored code group group corresponding to the sum of the slot values for each code group unit; If there are a plurality of code groups corresponding to the selected pre-stored code group group, each code group corresponding to the selected code group group and the code group of the received second synchronization channel are compared to determine the code group of the received second synchronization channel. Obtaining a fifth step; And if the selected pre-stored code group group corresponds to a single code group, determine the code group of the received second synchronization channel as the single code group without performing the comparison operation of the fifth step. A sixth step is performed.

1 is a diagram illustrating a structure of a synchronization channel in a wideband code division multiple access scheme which is an asynchronous scheme proposed as a standard.

2 is a diagram illustrating an example of a code group obtaining apparatus according to an embodiment of the present invention in an asynchronous W-CDMA system.

3 is a flowchart illustrating a code group obtaining method according to an embodiment of the present invention in an asynchronous wide area code division multiple access system.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, numerous specific details are set forth, such as a specific configuration, which are provided to assist in a more general understanding of the present invention, and the present invention may be practiced without these specific details. It is self-evident to those who have. 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. The above objects, features and advantages will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.

In the asynchronous W-CDMA system, an apparatus and method for acquiring a code group according to an embodiment of the present invention sums the values of all slots in a code group of a second synchronous channel to be received before performing an operation of determining and acquiring a code group. The number of code groups to be compared can be significantly reduced by using the previously calculated code group group. As a result, the time required for acquiring the code group can be shortened to prevent unnecessary power consumption, thereby prolonging the terminal power life, and supporting fast cell search during handoff. In addition, roaming between heterogeneous networks can be achieved quickly with the same asynchronous W-CDMA system.

According to an exemplary embodiment of the present invention, the receiving end stores the sum of slots of each code group of a predetermined number (eg, 64) designated as a standard. At this time, the number of the code group corresponding to each slot sum value is bundled. For example, referring to the above figure, code groups in which the slot sum value of the code group is "125" are Group # 13, Group # 39, and Group # 58 (hereinafter, having the same slot sum value for one frame period). The set of code groups is called " code group group ". Therefore, when the sum of the values of each slot in the code group of the second synchronous channel to be received becomes " 125 " Example: Group # 13, Group # 39, Group # 58 of the code group group whose slot sum value is "125", not Group # 0 to Group # 63) are selected, and the received code group is compared.

2 is a diagram illustrating an example of a code group obtaining apparatus according to an embodiment of the present invention in an asynchronous W-CDMA system. Hereinafter, a description will be given with reference to FIG. 1.

The storage unit 219 stores a plurality of code group groups having the same slot sum value for one frame period according to an embodiment of the present invention.

The first sync channel searcher 211 detects each slot start point of the first sync channel received from the base station (not shown) and outputs sync channel slot start position information.

The second synchronization channel searcher 213 recognizes each slot value of the second synchronization channel received from the base station in a code group unit of one frame period using the synchronization channel slot start position information. The second synchronous channel searcher 213 stores the slot values of the recognized code group in the storage 219.

The summer 215 sums the slot values of the recognized code group units according to an exemplary embodiment of the present invention.

The selector 217 selects a pre-stored code group group corresponding to the sum of the received slot values when the sum value of each slot value is input for each code group unit according to an exemplary embodiment of the present invention. In this case, the sum value of the slot values means a sum value of each slot value of the code group of the second synchronization channel received as described above.

The code group obtainer 221 compares each code group corresponding to the corresponding code group group with a code group of the received second synchronization channel according to an embodiment of the present invention. At this time, there may be various algorithms for the comparison operation. In an embodiment of the present invention, the reception code group stored in the storage unit 219 and each code group of the corresponding code group group may be sequentially compared. In this case, the comparison operation may compare each slot value of two code groups to be compared.

When the code group obtainer 221 finds the same code group as the code group of the second synchronization channel received among the code groups corresponding to the code group group, the code group obtainer 221 finds the received code group as the found code. Recognize as a group and complete the code group acquisition operation. The code group obtainer 221 transmits the code group acquisition result to a corresponding higher processor (not shown).

Meanwhile, if the code group group corresponding to the slot sum value of the code group of the received second synchronization channel corresponds to a single code group, the code group obtainer 221 corresponds to the received code. The group is determined as the single code group, and the code group acquisition result is transmitted to the upper processor without performing the comparison operation.

The controller 225 performs a code group acquisition operation by generally controlling the respective components of the code group acquisition apparatus according to the embodiment of the present invention.

Table 1 below shows a code group group having the same slot sum value for the values of the second synchronization code (SCC) of the second synchronization channel defined in the standard of 3GPP according to an embodiment of the present invention.

Sum value of second sync codes of respective code groups of second sync channel Code group group with same slot total 65 3 70 5 71 10 103 6 110 7 111 9 120 12,22,40 121 23 122 51 124 25,44 125 13,39,58 126 11,27,59 127 0,19,20,24,35,42,54 128 15,16,28 129 1,8,14,17,18,26,30,32 130 2,21,43,57 131 4,29,36,50,56 132 33 133 31,34,41,45,52 134 37,38 140 46 141 49 144 47 145 48 153 53 154 55 162 60 184 63 188 61 190 62

In Table 1, the left column represents the sum of the second synchronization codes SCC of each code group of the second synchronization channel, and the right column represents the plurality of code group groups having the same slot sum.

3 is a flowchart illustrating a code group acquisition method according to an embodiment of the present invention in an asynchronous wide area code division multiple access system. Hereinafter, a description will be given with reference to FIGS. 1 and 2.

The controller 225 controls the first sync channel searcher 211 to detect slot start points of the first sync channel received from the base station and provides sync channel slot start position information (step 311). ) Controls the second synchronization channel searcher 213 to recognize each slot value of the received second synchronization channel on a code group basis of one frame period using the synchronization channel slot start position information. The controller 225 controls the summer 215 to sum the slot values of the recognized code group units (step 315). The controller 225 controls the selector 217 to control the code. The prestored code group group corresponding to the sum of the slot values for each group unit is selected (step 317). The controller 225 controls the code group obtainer 221 to select the prestored code group group. The code group corresponding to multiple codes Check if it corresponds to a group (step 319).

If a code group corresponding to the selected pre-stored code group group corresponds to a plurality of code groups, the controller 225 controls the code group obtainer 221 to correspond to each code group corresponding to the selected code group group. The code group of the received second synchronization channel is obtained by comparing the code group of the received second synchronization channel (step 321). The controller 225 controls the code group obtainer 221 to control the code group. Report acquisition results to higher processor.

In step 225, if the code group corresponding to the selected pre-stored code group group corresponds to a single code group, the controller 225 controls the code group obtainer 221 to control the received second synchronization channel. The code group is determined as the single code group, and a code group acquisition operation is performed (step 325).

The controller 225 controls the code group obtainer 221 to report the result of the code group acquisition operation to the upper processor.

On the other hand, as described above, looking at the code group group (see <Table 2>) having the same slot sum value in one period frame interval with respect to the values of the second synchronization code (see Figure) presented in the current standard, a plurality of codes A total of 11 code group groups corresponding to the group (total 120, 124, 125, 126, 127, 128, 129, 130, 131, 133, 134).

In the total 11 cases, referring to the description of FIG. 3, the sum of code group sums of one frame period of the received second synchronization channel corresponds to a plurality of code group groups. In this case, the selected code group Each code group corresponding to the group (corresponding to a plurality of code groups) and the code group of the received second synchronization channel should be compared. Therefore, if the values of the second sync codes of the second sync channel presented in the standard have different slot sum values, steps 319 and 321 are omitted in FIG. 3, so that a faster code group acquisition is possible. Will lose.

On the other hand, the embodiment of Figure 3 is the case that the sum of the slots of the values of the second synchronization code of the second synchronization channel all have a different value, the case where all of the plurality of code groups, and <Table 1 Like this, it is applicable to both a code group group corresponding to a plurality of code groups and a code group group corresponding to a single code group.

Hereinafter, the code group acquisition algorithm according to an embodiment of the present invention in an asynchronous wide area code division multiple access system is analyzed in terms of an average code group acquisition time, which is the most important measure.

As described above, according to the conventional code group acquisition algorithm in the asynchronous W-CDMA system, the average time for the code group acquisition can be calculated as shown in Equation 1 above.

The time taken to compare a certain slot value included in the code group of the received second synchronization channel with a certain slot value included in the previously stored code groups is T, and the preprocessor before performing the operation of determining and acquiring the code group ( A time taken by the operation of the pre-processor (see reference numeral 223 of FIG. 2) is performed.

The average code group acquisition time by the code group acquisition algorithm according to the embodiment of the present invention may be represented by Equation 2 below.

Average code group acquisition time = A + [((((1 + 2) / 2) * 2 * 2 + ((1 + 2 + 3) / 3) * 3 * 4 + ((1 + 2 + 3 + 4) / 4) * 4 * 1

+ ((1 + 2 + 3 + 4 + 5) / 5) * 5 * 2 + ((1 + 2 + 3 + 4 + 5 + 6 + 7) / 7) * 7 * 1 + ((1 + 2 + 3 + 4 + 5 + 6 + 7 + 8) / 8) * 8 * 1) / 64] * 15 * T

= A + 31.41T

Here, T denotes a time taken to compare a certain slot value included in the code group of the received second synchronization channel with a certain slot value included in the previously stored code groups. A denotes a time taken by performing a pre-processing operation before performing an operation of determining and acquiring a code group.

Specifically, the following Equation 2 will be described.

First, a description of 31.41T is an average acquisition time taken by the code group obtainer 221 with values obtained through the pre-processor summer 215 and the selector 217. For example, if the value obtained through the preprocessor summer 215 and the selector 217 is "125", there are three code group numbers corresponding to 13, 39, and 58, and the probability of entering these codes is 3 / 64 Therefore, the code group obtainer 221 compares only three code groups 13, 39, 58 and code groups of the received second synchronization channel to obtain a code group of the received second synchronization channel, so that on average, (1+ A code group may be obtained at a time of 2 + 3) / 3. In the case of three code group numbers, the sum total is 120, 125, 126, and 128.Therefore, the formula (2) above contains ((1 + 2 + 3) / 3) * 3 * 4. do. The average acquisition time was calculated based on the number of code group numbers based on the <Table 1>, which is 31.41T in Equation 2, and the value of each slot (# 0 to # 14) of the code group in the process. For comparison, the time 15T and the probability related item 1/64 are backed out for convenience. One notable fact here is that, based on Table 1, when the number of code group numbers is 1, the code group is acquired, so that the time taken by the code group acquirer 221 is 0.

The time A taken through the pre-processor summer 215 and the selector 217 adds 15 slot values of the received second synchronization channel and stores the code group number corresponding to the added value. The time taken to return from the instrument 219 is very small. The time required to add the 15 values and to send the code group number already stored in the added value to the code group acquirer 221 will be minimal. (It is well known that addition is easy and fast.) Therefore, the time A in Equation 2 is less than 15T for comparing at least 15 values one by one. If it is minutes, there is no objection and the above Equation (2) will be expressed as the following upper limit for easy and quick comparison with the above (Equation 1).

A + 31.41T <= 15T + 31.41T = 46.41T

As shown in Equation 3, the algorithm proposed by the present invention is superior to the conventional Equation 1 in terms of average code group acquisition time, which is the most important measure, as mentioned in the standard. Is clearly presented mathematically. That is, the same function is performed with an acquisition time of less than 9.52% compared with the conventional method.

On the other hand, the present invention described above has been described with respect to specific embodiments, of course, various modifications are possible without departing from the scope of the invention. That is, the present invention is not limited to the above-described embodiments and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be evident to those who have knowledge of. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by the equivalents of the claims.

In the asynchronous W-CDMA system, an apparatus and method for acquiring a code group according to an embodiment of the present invention sums the values of all slots in a code group of a second synchronous channel to be received before performing an operation of determining and acquiring a code group. The number of code groups to be compared can be significantly reduced by using the previously calculated code group group. As a result, the time required for acquiring the code group can be shortened to prevent unnecessary power consumption, thereby prolonging the terminal power life, and supporting fast cell search during handoff. In addition, roaming between heterogeneous networks can be achieved quickly with the same asynchronous W-CDMA system.

Claims (3)

An apparatus for acquiring a code group in an asynchronous wide area code division multiple access system, A first sync channel searcher for detecting each slot start point of the received first sync channel and providing sync channel slot start position information; A second synchronous channel searcher for recognizing each slot value of a received second synchronous channel in units of a code group of one frame period using the synchronization channel slot start position information; A summer for summing slot values of the recognized code group units; A selector for selecting a pre-stored code group group corresponding to the sum of the slot values for each code group unit; And And a code group obtainer for obtaining a code group by comparing each code group corresponding to the corresponding code group group with a code group of the received second synchronization channel. The method of claim 1, wherein the code group obtainer, If the previously stored code group group selected by the selector corresponds to a single code group, performing the code group acquisition by determining the code group of the received second synchronization channel as the single code group without performing the comparison operation. Characterized in that the device. A code group acquisition method in an asynchronous wide area code division multiple access system, Detecting a slot start point of the received first sync channel and providing sync channel slot start position information; A second step of recognizing each slot value of a received second synchronization channel in units of code groups of one frame period by using the synchronization channel slot start position information; A third step of summing each slot value for each recognized code group unit; A fourth step of selecting a pre-stored code group group corresponding to the sum of the slot values for each code group unit; If there are a plurality of code groups corresponding to the selected pre-stored code group group, each code group corresponding to the selected code group group and the code group of the received second synchronization channel are compared to determine the code group of the received second synchronization channel. Obtaining a fifth step; And If the selected prestored code group group corresponds to a single code group, the code group acquisition is performed by determining the code group of the received second synchronization channel as the single code group without performing the comparison operation of the fifth step. And a sixth step.