KR100963788B1 - Method and apparatus for detecting paging indicator in orthogonal frequency division multiplexing based celluar communication system - Google Patents

Abstract

The present invention provides a method for a mobile terminal, in which a mobile terminal wakes up in a paging available interval allocated to itself in an idle mode and acquires a synchronization for performing paging indicator detection, and the synchronization acquisition result. Acquiring paging control information when the serving base station of the current paging valid period and the previous paging valid period is different according to the present invention; Detecting a paging indicator corresponding to the mobile terminal group to which the serving base station belongs, and determining whether to acquire paging control information using the detected paging indicator. to provide.

Paging Indicator, Transmit, Detect, Idle Mode

Description

METHOD AND APPARATUS FOR DETECTING PAGING INDICATOR IN ORTHOGONAL FREQUENCY DIVISION MULTIPLEXING BASED CELLUAR COMMUNICATION SYSTEM}

The present invention relates to a method and apparatus for detecting a paging indicator in a mobile communication system based on an orthogonal frequency division. More particularly, the present invention relates to a symbol configuration for transmitting a paging indicator for reducing power consumption of an idle mode mobile terminal, and a device suitable for the same. Paging indicator detection method and apparatus.

The present invention is derived from research conducted as part of the IT growth engine technology development project of the Ministry of Information and Communication and the Ministry of Information and Communication Research and Development. [Task Management Number: 2006-S-001-02, Title: Adaptive Wireless Access for 4th Generation Mobile Communications] And transmission technology development].

In a mobile communication scheme such as WCDM or CDMA 2000, a base station spreads and transmits a paging indicator using a channelization code, and a mobile terminal in idle mode is received with traffic data. A paging indicator is detected after dispreading using a channelization code for a paging indicator used by a base station to distinguish a paging indicator. The paging indicator uses on / off keying (OOK) or binary phase shift keying (BPSK) modulation. In order to compensate for the phase of the channel experienced by the paging indicator when the paging indicator is detected, the pilot channel is used to estimate the phase of the channel. As a result of detecting the paging indicator, the paging control information is decoded when the paging indicator is on or the reliability of the paging indicator is low, and re-enters the idle mode when the paging indicator is off.

On the other hand, orthogonal frequency division multiplexing (hereinafter, referred to as OFDM) scheme uses a plurality of carriers having mutual orthogonality, thereby increasing frequency utilization efficiency, and the process of performing modulation / demodulation of the plurality of carriers at each transceiver is performed by IDFT (Inverse). The result is the same as the Discrete Fourier Transform (Discrete Fourier Transform) and the DFT (Discrete Fourier Transform).

However, when a paging indicator is transmitted along with traffic data in an FFT-based OFDM based mobile communication system that separates channels using subcarriers, the entire symbol including traffic data is used to distinguish the subcarriers on which the paging indicator is transmitted. FFT must be performed on. Therefore, in the OFDM-based mobile communication system, as in the conventional CDMA-based mobile communication system, a method of simultaneously transmitting a paging indicator and data traffic is not suitable.

Therefore, there is an urgent need for a method of applying a paging indicator suitable for an OFDM-based mobile communication system.

The present invention effectively reduces the power consumption of a mobile terminal operating in the idle mode by applying a paging indicator in an OFDM-based mobile communication system to enable an efficient paging procedure in a mobile station in an idle mode. It provides a method and apparatus.

In the paging indicator detection method according to an embodiment of the present invention, the mobile terminal wakes up to a paging available interval allocated to itself in the idle mode, and performs synchronization for detecting a paging indicator. Obtaining paging control information when a serving base station of a current paging validity interval and a previous paging validity interval is different according to the synchronization acquisition result; and obtaining paging control information according to the synchronization acquisition result. When the serving base station of the current paging valid period and the previous paging valid period is the same, detecting a paging indicator corresponding to the mobile terminal group to which the mobile station belongs and determining whether to obtain paging control information using the detected paging indicator. It includes a step.

An apparatus for detecting a paging indicator according to an embodiment of the present invention includes a synchronization unit that wakes up to a paging available interval allocated to itself in an idle mode and acquires a synchronization for performing paging indicator detection; A paging control information acquisition unit for acquiring paging control information when a serving base station of a current paging valid period and a previous paging valid period is different according to the synchronization acquisition result; and current paging according to the synchronization acquisition result When the serving base station of the validity interval and the previous paging validity interval is the same, it is determined whether to obtain paging control information using a paging indicator detector for detecting a paging indicator corresponding to the mobile terminal group to which the mobile station belongs and the detected paging indicator. It includes a determination unit.

According to the present invention, an efficient paging procedure is performed in an idle mode mobile terminal by applying a paging indicator in an OFDM-based mobile communication system, thereby providing a method of effectively reducing power consumption of a mobile terminal operating in an idle mode. can do.

In addition, according to the present invention, when a dedicated PI symbol is used, symbol configuration for paging indicator transmission can be effectively performed.

In addition, according to the present invention, when the paging indicator is transmitted using the PI preamble, the paging indicator can be transmitted without increasing the overhead.

In addition, according to the present invention, when the paging indicator transmission scheme and idle mode mobile terminal paging procedure is applied to an OFDM-based mobile communication system, it is possible to perform efficient paging compared to an OFDM-based mobile communication system that does not use a paging indicator. The power of the mode mobile terminal can be effectively reduced, thereby increasing the battery life of the mobile terminal.

Hereinafter, a method and apparatus for detecting a paging indicator for reducing power consumption of a mobile terminal in an OFDM-based mobile communication system will be described in detail.

1 illustrates a configuration of a mobile communication system including an idle mode mobile terminal according to the present invention.

Referring to FIG. 1, one paging zone 1 and 2 are composed of one or more base stations BS1 to BS4, and the base stations BS1 to BS4 in one paging zone 1 and 2 are identical to each other. Send paging information. After the network entry procedure, the mobile station communicating with the base station operates all functions for its wireless modem and communication for transmitting and receiving data with the base station. Therefore, a large power consumption occurs in the mobile terminal communicating with the base station. If the modem continues to operate while the user of the mobile terminal does not communicate with the base station, battery life of the mobile terminal is reduced due to power consumption caused by unnecessary operation of the mobile terminal. Accordingly, in the current mobile communication system, an idle mode is used to increase the battery life of the mobile terminal by reducing power unnecessarily used by the mobile terminal during the service non-use time that takes up most of the time after the network registration procedure of the mobile terminal. Support operation. The mobile terminals 110 and 120 operate in the idle mode when not communicating with the base station, and during the idle mode, the mobile terminals 110 and 120 perform only functions for the next service use, and during most of the idle mode. Do not exchange data with the base station.

2 is a diagram illustrating an example of paging information for an idle mode mobile terminal.

1 and 2, the base stations BS1 to BS4 periodically provide paging information so that the idle mode mobile terminals 110 and 120 may receive the next service. Here, a period in which the base stations BS1 to BS4 provide paging information for the specific idle mode mobile terminals 110 and 120 is called a paging cycle, and the idle mode mobile terminals 110 and 120 are used during the paging cycle. At least once, the paging information is received from the base stations BS1 to BS4. The idle mode mobile terminals 110 and 120 are referred to as paging available intervals for receiving data from the base stations BS1 to BS4 in order to confirm paging information provided from the base stations BS1 to BS4. Paging control information including paging information for idle mode mobile terminals 110 and 120 is provided in the downlink frame corresponding to the paging valid duration. Paging valid interval allocation for a particular idle mode is determined by the base station (BS1 ~ BS4) or by a predefined method for operating the system, the idle mode mobile terminal (110, 120) itself is a base station (BS1 ~ ~) The paging valid period for receiving paging information from BS4) is known in advance. One paging valid period includes paging control information for a plurality of idle mode mobile terminals. A plurality of paging valid periods exist during one paging period, and the paging information is transmitted to different idle mode mobile terminals 110 and 120 for each paging valid period. The maximum number of idle mode mobile terminals 110 and 120 that can provide paging information during a particular paging valid period is the same as the maximum number of idle mode mobile terminals that can simultaneously provide paging information. The idle mode mobile terminal 110 or 120 wakes up from the paging valid interval assigned to the mobile station 110 and checks the paging information or the paging zone ID for the user through the paging control information, and then selects the active mode or the idle mode. Determine whether to re-enter.

A downlink frame structure including paging control information transmitted in a paging valid period is, for example, as shown in FIG. 3 when paging control information is transmitted over the entire frame or as shown in FIG. 4. There is a case where the paging control information exists within several symbols at the beginning of the frame.

5 is a diagram illustrating an operation of a wireless modem of a mobile terminal when decoding paging control information.

Referring to FIG. 5, a wireless modem of a mobile terminal includes a synchronizer 510 and a channel estimator including a carrier frequency offset (CFO) / symbol timing offset (STO) estimator 511 and a cell searcher 512. 521, a paging control information decoder 520 including a symbol detector 522, and a decoder 523.

The CFO / STO estimator 511 estimates a carrier frequency offset and estimates a symbol timing offset. The cell search unit 512 searches for cells. The synchronizer 510 performs synchronization through the CFO / STO estimator 511 and the cell searcher 512.

The channel estimator 521 estimates a channel from the traffic data symbols output from the synchronizer 510, the symbol detector 522 detects the symbol, and the decoder 523 decodes the paging control information.

As described above, the power consumption of the mobile terminal during the idle mode is directly related to the life of the battery. Therefore, the mobile communication system employs a technique of applying a paging indicator to reduce power consumption of the mobile terminal during idle mode. When the paging indicator is applied, mobile terminals in the idle mode are allocated to a specific paging group within one paging valid period, and each paging group is controlled by one paging indicator. The number of mobile terminals in idle mode included in the paging group within the paging valid interval is determined by the number of paging indicators that can be distinguished from the number of mobile terminals in idle mode in which paging control information transmitted in the corresponding paging valid interval provides paging information. As the number of idle terminals in the idle mode included in the paging group decreases, power consumption according to the idle mode indicator may be reduced.

6 is a diagram illustrating an operation of a wireless modem of an idle mode mobile terminal during a paging valid period when a paging indicator is applied.

Referring to FIG. 6, when the paging indicator is applied, the mobile terminal in the idle mode during the paging valid period performs synchronization acquisition through the synchronization unit 610. That is, the synchronization unit 610 of the mobile terminal wakes up from the paging valid period assigned to the mobile station in the idle mode, and then, through the CFO / STP estimator 611, uses the PI preamble to detect frame, timing, and carrier frequency offset synchronization. When the cell search unit 612 needs to perform a cell search using the PI preamble, the cell search unit 612 searches for a cell using the PI preamble. After acquiring synchronization, the mobile terminal needs to perform paging indicator detection through the paging indicator detector 620 and obtain paging control information by determining whether to obtain paging control information through a determination unit (not shown). Paging control information is decoded by the paging control information decoding unit 630 only when there is a P / C. That is, the paging control information decoding unit 630 decodes the paging control information when the serving base station of the current paging valid period and the previous paging valid period is different according to the synchronization acquisition result. The determination unit of the mobile terminal may determine whether to obtain the paging control information and determine whether the paging indicator is on or off.

As such, the idle mode mobile terminal to which the paging indicator is to be applied may acquire paging control information as needed and thereby reduce power consumption.

When the paging indicator transmission scheme according to the present invention is applied, the operation of the idle mode mobile terminal in the paging valid period is as follows.

The mobile terminal wakes up from a paging valid period allocated to the mobile terminal to acquire synchronization using a preamble, and if the synchronization is successfully acquired, the paging indicator detection unit 620 performs paging indicator detection. If the paging indicator is off when the paging indicator is detected, the mobile terminal does not decode the paging control information and re-enters the idle mode. That is, the determination unit of the mobile terminal determines paging control information detection or idle mode reentry depending on whether the paging indicator is on or off. If the synchronization acquisition fails, the mobile station performs a network entry procedure starting from an initial synchronization procedure, and when the paging indicator is on when the cell is changed or the reliability of the paging indicator is small, the paging control information decoder 630 Decode the paging control information through. The paging control information decoder 630 estimates a channel through the channel estimator 631, detects a symbol through the symbol detector 632, and decodes the paging control information through the decoder 633. After the mobile terminal decodes the paging control information, the mobile terminal obtains paging information and a paging area ID for the mobile terminal and determines whether the mobile device operates in the active mode. That is, when the paging indicator detection reliability is less than the reference value, the mobile terminal obtains paging control information including the paging information and the paging area ID through a paging control information acquisition unit (not shown).

Resource allocation methods for paging indicators in an OFDM-based mobile communication system can be classified into four types as follows.

7 is a diagram illustrating a frame structure when providing a paging indicator transmission scheme according to the first scheme.

8 is a diagram illustrating an operation of a wireless modem when detecting a synchronization and paging indicator when providing a paging indicator transmission scheme according to the first scheme.

7 and 8, the paging indicator according to the first scheme is transmitted through the MAC control channel for the paging indicator, in which case the paging indicator decoding is the same as the traffic data decoding procedure.

That is, the mobile terminal according to the first scheme performs synchronization acquisition through the synchronization unit 810 including the CFO / STO estimator 811 and the cell searcher 812. After synchronization acquisition, the PICH decoder 820 performs an FFT on the PICH (Paging Indicator Channel) symbol through the FFT unit 821 for the PICH symbol, detects the PICH symbol through the symbol detector 822, and decodes the decoder. Decode the PICH through 823.

The paging control information decoder 830 receives the traffic data symbol from the synchronizer 810, and receives a dedicated paging indicator message and other additional messages for decoding the paging control information from the PICH decoder 820. 831, the symbol detector 832 and the decoder 833 decode the paging control information.

In addition, the paging indicator according to the first scheme may have an advantage of paging operation by including additional control information such as channel decoding information and usage resources of paging control information other than the paging indicator, and may design an efficient paging indicator. Since channel coding is applied to MAC control information for the MAC, the accuracy of paging indicator detection is higher than that of other methods.

9 is a diagram illustrating a frame structure when the paging indicator transmission scheme according to the second scheme is applied.

FIG. 10 is a diagram illustrating an operation of a wireless modem when detecting a synchronization and paging indicator when the paging indicator transmission method according to the second scheme is applied.

9 and 10, a second method according to the present invention uses a binary phase shift (BPSK) using a subcarrier predefined by a comb type subcarrier allocation scheme in a specific symbol among OFDM symbols for traffic data in a paging valid period. Keying) or differential binary phase shift keying (DBPSK) modulated paging indicator. The synchronization unit 1010 performs synchronization acquisition through the CFO / STO estimator 1011 and the cell search unit 1012.

The idle mode mobile terminal according to the second scheme classifies a subcarrier for a paging indicator using a partial FFT unit 1021 for a PICH symbol and performs paging indicator detection. That is, the paging indicator detection unit 1020 uses some subcarriers among the symbols for traffic data and uses the partial FFT unit 1021, so that the paging indicator detection unit 1020 uses less overhead than the first scheme, and detects the paging indicator with less complexity. It is possible.

The paging control information decoder 1030 estimates a channel through the channel estimator 1031, detects a symbol through the symbol detector 1032, and decodes the paging control information through the decoder 1033. The determination unit (not shown) of the mobile terminal determines paging control information detection or idle mode re-entry according to on / off of the paging indicator when the reliability of the paging indicator detection is greater than or equal to a reference value.

11 is a diagram illustrating a frame structure when a paging indicator transmission scheme according to a third scheme is applied.

12 is a diagram illustrating an operation of a wireless modem when detecting a synchronization and paging indicator when the paging indicator transmission method according to the third scheme is applied.

11 and 12, a third method according to the present invention is a method of transmitting a paging indicator by adding a separate paging indicator symbol. When the paging indicator is transmitted using a separate paging indicator symbol according to the third scheme, the mobile terminal in the idle mode performs a synchronization acquisition of the synchronization unit 1210 using the preamble and then selects a paging indicator symbol upon successful synchronization acquisition. The paging indicator detection unit 1220 performs the paging indicator detection using the.

The synchronizer 1210 performs synchronization acquisition through the CFO / STO estimator 1211 and the cell searcher 1212.

The paging indicator detector 1220 detects the paging indicator by using a PI preamble when the current paging valid period and the previous paging valid period are the same. The paging indicator detector 1220 performs an FFT on the dedicated PI symbol through the FFT unit 1221 for the PICH symbol, and detects a paging indicator symbol through the symbol detector 1222.

The determination unit (not shown) of the mobile terminal determines paging indicator detection reliability using dedicated PI symbol interference when the current paging validity interval and the serving base station of the previous paging validity interval are the same.

The paging control information decoder 1230 estimates a channel through the channel estimator 1231, detects a symbol through the symbol detector 1232, and decodes the paging control information through the decoder 1233. In this case, the determination unit of the mobile terminal determines paging control information detection or idle mode re-entry according to on / off of the paging indicator when the reliability of the paging indicator detection is greater than or equal to the reference value.

As described above, the third method according to the present invention has an advantage of enabling efficient paging indicator design by transmitting a paging indicator using a paging indicator dedicated symbol.

13 is a diagram illustrating a frame structure when the paging indicator transmission scheme according to the fourth scheme is applied.

14 is a diagram illustrating an operation of a wireless modem when detecting a synchronization and paging indicator when the paging indicator transmission method according to the fourth scheme is applied.

13 and 14, a fourth method according to the present invention is a method of detecting a paging indicator during a synchronization process using a preamble by adding paging indicator information to a frequency domain sequence of the preamble. When the paging indicator information is added to the preamble sequence and transmitted according to the fourth scheme, a schematic synchronization procedure and a paging indicator detection procedure of an idle mode mobile terminal are as follows.

The synchronization unit 1410 of the mobile terminal according to the fourth scheme performs a symbol timing offset and a carrier frequency offset estimator 1411 when the frame detection is successful after the frame detection is performed. The symbol timing offset and the carrier frequency offset are estimated, the cell search unit 1412 performs the cell search, and the paging indicator detector 14130 detects the paging indicator.

As such, in the fourth scheme according to the present invention, since the paging indicator is transmitted using the preamble sequence, no overhead occurs. In addition, the paging indicator detector 1413 according to the fourth scheme does not perform a separate FFT since the paging indicator detection unit uses the preamble sequence of the frequency domain when the paging indicator is detected. Therefore, the fourth scheme according to the present invention has a gain over the first to third schemes in terms of complexity for detecting overhead or paging indicator.

The paging control information decoder 1420 of the mobile terminal according to the fourth scheme estimates a channel through the channel estimator 1421, detects a symbol through the symbol detector 1422, and uses a decoder 1423. Decode the paging control information. In this case, the determination unit (not shown in the drawing) of the mobile terminal may determine paging control information detection or idle mode re-entry according to on / off of the paging indicator when the reliability of the paging indicator detection is greater than or equal to a reference value. .

The present invention proposes a symbol and preamble design technique including a paging indicator for an OFDM mobile communication system using the second to fourth schemes, and a synchronization and paging indicator acquisition procedure suitable for the same.

In the present invention, a data transmission symbol including a paging indicator transmission subcarrier is called a paging indicator (PI) symbol, a separate paging indicator symbol including only paging indicator information is called a dedicated PI symbol, and includes paging indicator information. The preamble is called a PI preamble. The case of the step before including the paging indicator information in the PI preamble configuration is called a preamble.

In the case of using the PI symbol, the mobile terminal in the idle mode acquires a subcarrier for the paging indicator using a partial FFT to detect the paging indicator in the paging valid period.

Dedicated PI symbol configuration is divided into three types as follows.

The first method of configuring a dedicated PI symbol according to the present invention transmits on / off information of a paging indicator by using a modulation signal using BPSK or DBPSK. The idle mode indicator uses a modulation method for detecting a paging indicator. Paging indicator detection is performed through a demodulation technique suitable for the < RTI ID = 0.0 >

According to the second method of configuring a dedicated PI symbol according to the present invention, a different subcarrier set is allocated to each paging indicator and a paging indicator signal is transmitted through a corresponding subcarrier set when a paging indicator assigned to a specific paging group is on. The mode indicator detects the power of the subcarrier set to determine on / off of the paging indicator.

A third method of configuring a dedicated PI symbol according to the present invention uses a sequence for transmitting paging indicator information. The idle mode indicator uses a correlation value of a paging indicator sequence when detecting a paging indicator. In the present invention, a sequence transmitted for transmitting paging indicator information is called a paging indicator sequence.

15 shows a conceptual diagram of each dedicated PI symbol configuration scheme.

Referring to FIG. 15, in order to increase the reliability of the paging indicator detection result, the paging indicator may be repeatedly transmitted (1510 to 1530). When the paging indicator is repeatedly transmitted, the number of mobile terminals included in each paging group within the paging validity interval is inversely proportional to the number of repetitions of the paging indicator.

16 is a diagram illustrating a concept of an on / off classification method of a paging indicator.

Referring to FIG. 16, the on / off classification of the paging indicator may vary according to each transmission scheme, and may be classified into a scheme using a phase 1610, a scheme using a sequence 1620, and a scheme using a subcarrier position 1630. Can be divided.

The determination unit of the mobile terminal may determine on / off of the paging indicator by using the position, phase, sequence of the paging indicator of the symbol, or the power transmitted on the designated subcarrier of the symbol when configuring the PI symbol.

Hereinafter, a dedicated PI symbol configuration method considering the BPSK modulated paging indicator will be described in more detail.

는

번째 페이징 인디케이터,

는 파일롯 시퀀스의

번째 원소,

는 FFT 크기,

은 DC 반송파 주파수,

는

번째 페이징 인디케이터에 할당된 부반송파 위치,

은 파일롯 시퀀스의

번째 원소에 할당된 부반송파 위치,

는 전용 PI 심볼에서 사용되는 부반송파 인덱스,

는 하나의 전용 PI 심볼에서 전송 가능한 페이징 인디케이터의 총 개수,

는 파일롯 시퀀스의 길이이다.here,

Is

First paging indicator,

Of the pilot sequence

The first element,

Is the FFT size,

Is the DC carrier frequency,

Is

Subcarrier position assigned to the first paging indicator,

Of the pilot sequence

Subcarrier position assigned to the first element,

Is the subcarrier index used in the dedicated PI symbol,

Is the total number of paging indicators that can be sent in one dedicated PI symbol,

Is the length of the pilot sequence.

까지의 정수이다. BPSK 변조된 페이징 인디케이터 전송시 고려되는 파일롯은 전용 PI 심볼 구성시 오버헤드로 작용하여 하나의 전용 PI 심볼을 통해 전송 가능한 페이징 인디케이터의 총 개수를 감소시킨다. DBPSK 변조된 페이징 인디케이터를 이용한 경우 DBPSK 신호의 복조를 위해 전용 PI 심볼은 파일롯 대신 기준 신호를 포함하여야 하며 페이징 인디케이터 전송을 위해 사용된 부반송파는 인접한 부반송파와 코히어런스(coherence) 대역폭 내에 존재해야 한다. DBPSK 변조된 페이징 인디케이터를 이용한 경우에는 채널 추정을 위한 파일롯이 존재하지 않기 때문에 BPSK 변조된 페이징 인디케이터 전송시에 비해 하나의 전용 PI 심볼을 통해 더 많은 수의 페이징 인디케이터를 전송할 수 있다. The subcarrier index is from 0

Is an integer up to. The pilot considered in the transmission of the BPSK modulated paging indicator acts as an overhead in configuring a dedicated PI symbol, thereby reducing the total number of paging indicators that can be transmitted through one dedicated PI symbol. In the case of using the DBPSK modulated paging indicator, the dedicated PI symbol should include a reference signal instead of a pilot for demodulation of the DBPSK signal, and the subcarriers used for the transmission of the paging indicator should exist within adjacent subcarriers and coherence bandwidth. In the case of using the DBPSK modulated paging indicator, since there is no pilot for channel estimation, a larger number of paging indicators can be transmitted through one dedicated PI symbol than when transmitting a BPSK modulated paging indicator.

17 shows a configuration of a dedicated PI symbol when a BPSK modulated paging indicator is used.

In the case of using the first dedicated PI symbol configuration method, if a BPSK modulated paging indicator is used, channel estimation and compensation processes are required for coherent detection when detecting a paging indicator. However, in case of using DBPSK modulation, paging indicator can be detected without channel estimation. Detection of the BPSK modulated paging indicator is as follows.

,

은 각각 부호 변수의 부호를 취하는 함수와 변수의 실수 값만을 취하는 함수이며,

와

는 각각 수신 신호의 주파수 영역 신호와 파일롯을 이용하여 추정된 채널을 의미한다.here,

,

Are functions that take the sign of the sign variable and only the real value of the variable.

Wow

Denotes a channel estimated using the frequency domain signal and the pilot of the received signal, respectively.

When the same subcarrier is used between adjacent base stations when the first dedicated PI symbol configuration scheme is applied, if the paging indicator information is the same, there is no interference between cells, but if the adjacent base stations transmit different paging indicator information, there is interference between cells. That is, when different base stations use the same subcarrier for dedicated PI symbol transmission, the base stations in the paging area transmit the same paging indicator information, so that there is no cell interference between base stations in the paging area, but adjacent base stations exist in different paging areas. Since PBs transmit different paging indicator information, interference occurs between adjacent cells. The reliability of the paging indicator detection result is decreased in the presence of intercell interference, and the reliability of the paging indicator detection result is decreased when the noise experienced by the received PI is large even when there is no cell interference. When the reliability of the paging indicator detection result is low, since the reliability of the paging indicator detection result is decreased, the mobile terminal may cause an increase in paging response latency or a paging drop. Here, the page response latency refers to a delay time after the idle mode mobile terminal receives paging control information including paging information about itself and transmits a response message to the base station, and the paging drop corresponds to a paging request of the base station. Indicates that the mobile terminal does not respond. Therefore, when the amount of inter-cell interference and noise is large, the reliability of the detection result of the paging indicator decreases. In this case, the idle mode mobile terminal must decode the paging control information without performing paging indicator detection. A paging indicator reliability determination procedure is required, and in the presence of intercell interference, a cell to interference and noise ratio (CINR) measurement procedure using a preamble or a pilot received from an adjacent cell and a paging indicator reliability determination due to intercell interference are required. After detecting the paging indicator, the mobile terminal of the idle mode determines whether or not to decode paging control information through the reliability determination procedure of the paging indicator. When subcarriers used for dedicated PI symbol transmission do not overlap between neighboring cells, even if paging indicator information is different, there is no inter-cell interference.

The following is an example of a second dedicated PI symbol configuration method using on / off keying and an orthogonal code.

와

는 각각 전용 PI 심볼에서 사용되는 부반송파 중

번째 페이징 인디케이터 전송을 위해 사용되는 부반송파 인덱스를 나타낸다.here,

Wow

Is the subcarrier used in each dedicated PI symbol.

Subcarrier index used for the first paging indicator transmission.

는 페이징 인디케이터 정보를 추가하기 전의 전용 PI 심볼,

는 페이징 인디케이터 정보를 추가한 전용 PI 심볼,

는 전용 PI 심볼 생성을 위해 사용되는 시퀀스의

번째 원소,

는 전용 PI 심볼에서 전용 PI 심볼 생성을 위해 사용되는 시퀀스(전용 PI 심볼 시퀀스)의

번째 원소가 실리는 부반송파 인덱스,

는 전용 PI 심볼에서 사용되는 부반송파 중

번째 페이징 인디케이터에 할당된 부반송파 인덱스,

는 모듈로 연산자를 나타낸다. here,

Is the dedicated PI symbol before adding the paging indicator information,

Is a dedicated PI symbol appended with paging indicator information,

Is the sequence of sequences used to generate the dedicated PI symbols.

The first element,

Is a sequence of sequences used to create a dedicated PI symbol from a dedicated PI symbol (a dedicated PI symbol sequence).

Subcarrier index containing the first element,

Is the subcarrier used in the dedicated PI symbol.

Subcarrier index assigned to the first paging indicator,

Represents the modulo operator.

In Equation 3, when the paging indicator is on, 1 is transmitted to the subcarrier set of the corresponding paging indicator, and when it is off, 0 is transmitted.

번째 페이징 인디케이터에 할당된 부반송파를 통하여 전송된 신호는 오프인 경우와 온인 경우가 서로 직교하도록 만들어준다. 상기 수학식 4에서는 2개의 부반송파를 이용하여 하나의 페이징 인디케이터 정보를 전송하도록 전용 PI 심볼을 구성하였지만 더 많은 부반송파를 이용할 수도 있다. 이 때 하나의 페이징 인디케이터 전송을 위해 사용되는 부반송파는 직교성 유지를 위해 모두 코히어런스 대역폭 내에 존재해야 한다. In Equation 4, when the paging indicator is off, the dedicated PI symbol sequence is transmitted as it is, but when it is on, the sequence is changed as in Equation 4 and transmitted. in this case

The signal transmitted through the subcarrier allocated to the first paging indicator is made to be orthogonal to off and on. In Equation 4, a dedicated PI symbol is configured to transmit one paging indicator information using two subcarriers, but more subcarriers may be used. At this time, the subcarriers used for transmitting one paging indicator must all exist within the coherence bandwidth to maintain orthogonality.

18 and 19 show structures of a dedicated PI symbol generated using Equations 3 and 4, respectively.

In case of applying Equation 3, paging indicator detection is as follows.

In a dedicated PI symbol configuration using a second dedicated PI symbol configuration method, when different paging indicators use the same subcarrier, power measurement cannot be used, so the subcarrier sets between paging should be different.

Therefore, base stations belonging to different paging areas should transmit dedicated PI symbols using different subcarriers. The idle mode mobile terminal does not consider the reliability of the paging indicator due to intercell interference, and performs only the noise estimation and the determination of the reliability of the paging indicator through the determination unit to determine whether to decode the paging control information after detecting the paging indicator.

The following is an embodiment of a dedicated PI symbol configuration applying the third dedicated PI symbol configuration method.

는

번째 페이징 인디케이터 시퀀스의

번째 원소,

는 전용 PI 심볼 시퀀스의

번째 원소,

는 전용 PI 심볼 전송을 위해 사용하는 부반송파 수,

는 하나의 페이징 인디케이터가 전송되는 부반송파 그룹에 포함되는 부반송파의 수이다.

는

이하의 양의 정수이며,

은

의 배수이다.here,

Is

Of the first paging indicator sequence

The first element,

Is the only PI symbol sequence

The first element,

Is the number of subcarriers used to transmit dedicated PI symbols,

Is the number of subcarriers included in the subcarrier group in which one paging indicator is transmitted.

Is

Is a positive integer

silver

Is a multiple of.

In Equation 7 and Equation 8, the sequence may be divided into a case where the paging indicator is turned on and off and a case in which the sequence is transmitted only when the paging indicator is on.

20 and 21 illustrate a configuration of a dedicated PI symbol when using Equations 7 and 8, respectively.

번째 페이징 인디케이터가 전송되는 부반송파 그룹으로 전송된 페이징 인디케이터의 검출은 다음과 같다. 이 경우 상호 상관에 사용되는 부반송파 수는

이다.When the PI preamble is configured using Equation 7

Detection of the paging indicator transmitted to the subcarrier group in which the first paging indicator is transmitted is as follows. In this case, the number of subcarriers used for cross correlation

to be.

번째 페이징 인디케이터가 전송되는 부반송파 그룹으로 전송된 페이징 인디케이터의 검출은 다음과 같다. 이 경우 상호 상관에 사용되는 부반송파 수는

이다. When the PI preamble is configured using Equation 9

Detection of the paging indicator transmitted to the subcarrier group in which the first paging indicator is transmitted is as follows. In this case, the number of subcarriers used for cross correlation

to be.

In Equations 9 and 10, the paging indicator is detected using the magnitude of the correlation value. However, if the paging indicator sequence used in Equation 7 or Equation 8 includes phase information, paging indicator detection may be performed using the phase. The following is an embodiment of configuring a dedicated PI symbol using a paging indicator sequence including phase information.

는 페이징 인디케이터 시퀀스의

번째 원소에 페이징 인디케이터의 온/오프에 따른 위상 정보를 추가한 경우로 페이징 인디케이터의 온/오프에 따라 페이징 인디케이터 전송을 위한 시퀀스의 홀수 번째 원소의 위상을 변화시킨다. here,

Of the paging indicator sequence

In the case where the phase information according to the on / off of the paging indicator is added to the first element, the phase of the odd-numbered element of the sequence for transmitting the paging indicator is changed according to the on / off of the paging indicator.

22 and 23 illustrate a preamble structure of a third dedicated PI symbol configuration method constructed using Equations 13 and 12, respectively.

번째 페이징 인디케이터가 전송되는 부반송파 group으로 전송된 페이징 인디케이터의 검출은 다음과 같다. 이 경우 상호 상관에 사용되는 부반송파 수는

이다.When a dedicated PI symbol is configured using Equation 11

Detection of the paging indicator transmitted to the subcarrier group in which the first paging indicator is transmitted is as follows. In this case, the number of subcarriers used for cross correlation

to be.

는 검출된 페이징 인디케이터 정보이다.here,

Is detected paging indicator information.

번째 페이징 인디케이터가 전송되는 부반송파 그룹으로 전송된 페이징 인디케이터의 검출은 다음과 같다. When a dedicated PI symbol is configured using Equation 12

Detection of the paging indicator transmitted to the subcarrier group in which the first paging indicator is transmitted is as follows.

Both the magnitude and phase of the correlation value can be used for paging indicator detection. In the case of using Equations 11 and 12, both the magnitude of the correlation value and the phase may be used to detect the paging indicator.

The cross-correlation procedure eliminates the need for channel estimation and compensation when detecting paging indicators. However, since the synchronization and channel performance affects the correlation characteristics of the sequence, it is necessary to appropriately allocate resources according to the synchronization performance and channel conditions of the system.

In the third dedicated PI symbol configuration method, adjacent base stations use the same subcarrier for dedicated PI symbol transmission and change phase information for one sequence when detecting paging indicator using phase as shown in Equations 11 and 12. In the case of differentiating the on / off, if the adjacent base station transmits different paging indicator information, paging indicator detection performance degradation due to inter-cell interference occurs. That is, when the same dedicated PI symbol sequence is used for all base stations, base stations belonging to the same paging zone transmit the same paging indicator information, so that two neighboring base stations belonging to different paging zones have different paging indicators. As a result, paging indicator detection performance due to intercell interference is degraded. In this case, inter-cell interference can be mitigated by constructing a dedicated PI symbol using different dedicated PI symbol sequences having good correlation characteristics for each base station or by distinguishing ON / OFF of a paging indicator using a sequence having good correlation characteristics. In addition, when the on / off of the paging indicator is distinguished using a sequence having good correlation characteristics, or when neighboring base stations transmit dedicated PI symbols using different subcarriers, interference between adjacent cells can be mitigated. In the third dedicated PI symbol configuration method, the inter-cell interference and noise are estimated after the detection of the paging indicator, and the determination unit determines whether to decode the paging control information by performing paging indicator reliability determination. In the third dedicated PI symbol configuration method, the paging indicator detection is performed using the result of the correlation value, thereby reducing the effects of interference and noise when detecting the paging indicator.

As described above, the determination unit of the mobile terminal according to the present invention determines the reliability of the paging indicator detection using the noise estimated using the preamble or the noise estimated using the dedicated PI symbol, or the inter-cell estimated using the cell search result. When the interference is used or each base station uses a different dedicated PI symbol sequence, the paging indicator detection reliability may be determined using the inter-cell interference estimated using the dedicated PI symbol.

However, when performing cell search and paging indicator detection using cross-correlation, more subcarriers are required than the first dedicated PI symbol configuration to transmit one paging indicator. Therefore, if the number of subcarriers used in the idle mode mobile terminal and the preamble can be simultaneously called per frame is determined, the number of paging indicators can be reduced because the number of paging indicators that can be distinguished is smaller than that of the first dedicated PI symbol configuration when using the correlated paging indicator transmission method. Increases. If only one idle mode mobile terminal of the idle mode mobile terminal in the paging group is turned on, the idle mode mobile terminals in which the paging control information does not exist in the paging control information of the idle mode mobile terminals belonging to the same paging group are also included. Since the paging control information needs to be decoded, the power consumption reduction efficiency due to the application of the paging indicator is reduced.

Therefore, in order to increase the number of paging indicators that can be transmitted by using one dedicated PI symbol or to increase the length of a sequence for transmitting a paging indicator, a mathematic of transmitting only one paging indicator through each subcarrier set when configuring a dedicated PI symbol. Unlike the embodiment of Equation 7 to Equation 14, the case in which the paging indicator uses the same subcarrier set may be considered. In this case, paging indicators transmitted through the same subcarrier set must be distinguished using sequences having good cross-correlation characteristics.

The PI preamble is configured by adding paging indicator information to a preamble provided for synchronization by the system, and plays a role of a preamble used for generating a PI preamble and a transmission of a paging indicator. Since no paging indicator symbol is used, the overhead is minimized and the paging indicator is detected during the synchronization procedure, thereby minimizing the power for detecting the paging indicator.

When using the PI preamble, the PI preamble sequence configuration can be largely divided into two types.

The first PI preamble sequence configuration method multiplies the preamble sequence by a paging indicator generated using a modulation scheme such as BPSK or DBPSK. In this case, if cell search or integer carrier frequency offset estimation is to be performed using a PI preamble, two adjacent subcarriers of a subcarrier are multiplied by the same paging indicator information to minimize performance degradation due to paging indicator information when performing cell search and integer carrier frequency offset. can do. When detecting the paging indicator information, the paging indicator is detected using a demodulation scheme suitable for the modulation scheme used for generating the paging indicator.

The second PI preamble sequence configuration method uses a paging indicator sequence to transmit paging indicator information and adds paging indicator information to the subcarriers used in the preamble symbol. When using the second method, paging indicator detection can be detected using the magnitude or phase of the correlation value. The synchronization procedure depends on the method used in PI preamble generation.

24 and 25 illustrate a concept of a PI preamble design of a first and second PI preamble configuration schemes, respectively.

In order to increase the reliability of the paging indicator detection result, the paging indicator may be repeatedly transmitted in some cases. When the paging indicator is repeatedly transmitted, the number of mobile terminals included in each paging group within the paging validity interval is inversely proportional to the number of repetitions of the paging indicator.

26 and 27 illustrate a synchronization procedure and a paging indicator detection procedure of an idle mode mobile terminal using a PI preamble in a paging valid period when the first PI preamble sequence configuration scheme is applied.

26 and 27, the idle mode mobile terminal receives a frame in a paging valid period allocated to the mobile terminal (2601), and determines whether the received frame is a PI preamble symbol or a traffic data symbol (2602). If the received frame is a traffic data symbol, the idle mode mobile terminal determines whether data decoding is possible (2603), and if decoding is possible, decodes data (2604).

If the received frame is the PI preamble, the mobile terminal determines whether the idle mode, the active mode or the initial synchronization (2605).

In the idle mode, the mobile terminal performs frame detection and symbol timing acquisition using a symbol corresponding to a PI preamble (2606). After the timing synchronization is acquired, the idle mode mobile terminal estimates a carrier frequency offset (2607). The mobile terminal estimates a cell search or integer carrier frequency offset (CFO) (2608) and determines whether the base station is changed (2609). When the base station is changed, the mobile terminal decodes data for paging control information (2610). If the base station is not changed, the idle mode mobile terminal checks the reliability of the paging indicator (2611) and determines whether the reliability of the paging indicator is higher than the reference value (2612).

If it is determined that the reliability of the paging indicator is lower than a reference value, the mobile terminal acquires paging control information without performing paging indicator detection (2610). If it is determined that the reliability of the paging indicator is higher than a reference value and determined to be a reliable level, the mobile terminal performs paging indicator detection (2613).

The mobile terminal determines whether the paging indicator is on as a result of detecting the paging indicator (2614), obtains paging control information when the paging indicator is on (2610), and idle mode when the paging indicator is off (2610). Re-enter (2615). The timing and frequency tracking process is performed as necessary when acquiring paging control information, which is not considered in FIG. 26.

The initial synchronization mobile terminal acquires frame detection and symbol timing (2616), estimates carrier frequency offset (2617), estimates cell search or integer carrier frequency offset (2618), and performs DL broadcast control information and network entry. The data is decoded (2619).

The active mode mobile terminal acquires frame detection and symbol timing (2620), estimates carrier frequency offset (2621), and determines whether handover is necessary (2622). If the handover is necessary, the active mode mobile terminal performs a handover procedure (2623). If the handover is not necessary, the active mode mobile terminal decodes data for DL broadcast control information and user data (2624).

The preamble sequence used for generating the PI preamble is performed only when the cell search or integer carrier frequency offset estimation should be performed. The cell search or integer carrier frequency offset estimation is performed after the synchronization process. If it is determined that the cell has been changed after the cell search is performed, paging control information is obtained to perform idle handover and location update.

If the preamble sequence used to generate the PI preamble is not a cell search sequence, the cell search is performed using the cell search preamble, and if the cell is changed after determining whether to change the cell using the cell search result, the idle handover is performed. And acquire paging control information for performing location update.

The following shows an embodiment of configuring a PI preamble sequence for a DBPSK modulated paging indicator when the first PI preamble sequence configuration method is applied.

는 송신 기지국의 프리앰블 인덱스,

는 프리앰블 시퀀스의 길이,

는 프리앰블 인덱스가

인 경우의 프리앰블 시퀀스이며, 프리앰블 시퀀스의 원소는 실수 또는 복소수이다.

는

번째 페이징 인 디케이터로서 프리앰블 시퀀스의 짝수/홀수 번째 원소에 곱해진다. 프리앰블 시퀀스의

번째 인덱스의 원소는 프리앰블 부반송파 중 DC 부반송파에 실리는 원소이다. 여기서

는 FFT 크기보다 작아야 하고,

는 0이 아닌 수이다. 첫 번째 PI 프리앰블 시퀀스 구성 방식을 적용한 경우 기지국에서의 주파수 영역 PI 프리앰블 심볼은 다음과 같다.here,

Is the preamble index of the transmitting base station,

Is the length of the preamble sequence,

Has a preamble index

Is a preamble sequence, and the elements of the preamble sequence are real or complex.

Is

As the first paging indicator, the even / odd elements of the preamble sequence are multiplied. Preamble sequence

The element of the first index is an element carried on the DC subcarrier among the preamble subcarriers. here

Must be smaller than the FFT size,

Is a nonzero number. When the first PI preamble sequence configuration method is applied, the frequency domain PI preamble symbol at the base station is as follows.

은 FFT 크기,

는 DC 반송파 주파수,

는 PI 프리앰블 시퀀스의

번재 원소,

는 PI 프리앰블 시퀀스의

번재 실리는 부반송파 인덱스이다. here,

Is the FFT size,

Dc carrier frequency,

Of the PI preamble sequence

Floating Element,

Of the PI preamble sequence

The third carrier is the subcarrier index.

FIG. 30 is a diagram illustrating a PI preamble structure constructed using Equation 15. FIG.

When the cross-correlation property of the preamble sequence corresponding to each preamble index is good, the cell search can be performed using the preamble. When the first PI preamble sequence configuration scheme is applied as shown in Equation 15, when the interval between adjacent subcarriers of the preamble symbol is smaller than the coherence bandwidth of the radio channel experienced by the received preamble, it is detected after performing cell search. The preamble index is a preamble index value that maximizes the magnitude of the correlation between the received PI preamble and the available preamble signal. When performing correlation, addition is performed on multiplication of adjacent subcarriers among the PI preamble and the preamble used in the preamble. The multiplication pair is a signal corresponding to a subcarrier index corresponding to an even-numbered preamble sequence and an odd-numbered preamble sequence, respectively, wherein the odd-numbered preamble index has a value greater than the even-numbered preamble index. When performing multiplication, a conjugate complex value is used for a subcarrier signal corresponding to an even / odd preamble index in a PI preamble and a conjugate complex value for a subcarrier signal corresponding to an odd / even number preamble sequence in a preamble. The following equation is an expression of the cell search method described above.

는 수신된 프리앰블의 주파수영역 신호,

는 는 프리앰블 인덱스가

인 프리앰블 시퀀스이다. 셀 탐색 수행시 PI 프리앰블에서 사용되는 부반송파 중 인접한 두 부반송파의 켤레복소수를 이용한 곱은 셀 탐색 과정에서 심볼 타이밍 옵셋에 의한 영향을 감소시키는 효과도 수반한다.here,

Is a frequency domain signal of the received preamble,

Has a preamble index

Preamble sequence. When performing a cell search, a product using a conjugate complex number of two adjacent subcarriers among the subcarriers used in the PI preamble also has an effect of reducing the influence of the symbol timing offset during the cell search.

When cell search and integer frequency estimation are to be performed, integer frequency offset estimation and cell search in the frequency domain are as follows.

의 범위는 정수배 주파수 옵셋 발생 범위와 같다.here,

The range of is equal to the integer frequency offset generation range.

When the paging indicator is transmitted using the first PI preamble sequence configuration method, the preamble sequence corresponding to the preamble index obtained in the cell search procedure and the integer frequency estimation result are used during the paging indicator detection process. When the paging indicator is BPSK modulated, coherent detection is applied, and channel estimation and compensation processes are required for paging indicator detection. However, in case of using DBPSK modulation, paging indicator can be detected without channel estimation. Detection of the DBPSK modulated paging indicator is as follows.

,

는 각각 부호 변수의 부호를 취하는 함수와 변수의 실수 값만을 취하는 함수이다.here,

,

Are functions that take the sign of the sign variable and only take the real value of the variable.

In the first PI preamble sequence configuration method, when the PI preambles transmitted between adjacent base stations are transmitted through the same subcarrier, the paging indicator information transmitted from each base station is different even if the preamble sequences used between the base stations are different or the preamble sequences between the base stations are the same. Inter-cell interference occurs. Since base stations in one paging area transmit the same paging indicator information to each other, there is no cell interference when all base stations transmit the same preamble sequence in the paging area. However, since the paging indicator information between the paging zones is different, interference occurs even when the same preamble is used between adjacent cells in different paging zones. In the presence of inter-cell interference, the reliability of the paging indicator detection result is reduced, and even if there is no cell interference, the reliability of the paging indicator detection result is reduced when the noise experienced by the received PI is large. When the reliability of the paging indicator detection result is low, since the reliability of the paging indicator detection result is decreased, the mobile terminal may cause an increase in paging response latency or a paging drop. Paging response latency refers to the delay time after the idle mode mobile terminal receives paging control information including paging information about itself and transmits a response message to the base station, and the paging drop corresponds to the corresponding paging request of the base station. The terminal does not respond. Therefore, when the amount of inter-cell interference and noise is large, the reliability of the detection result of the paging indicator decreases. In this case, the idle mode mobile terminal does not perform paging indicator detection and decodes the paging control information. Paging indicator reliability determination procedure is required, and in the presence of intercell interference, a CINR measurement procedure using a PI preamble received from an adjacent cell and a paging indicator reliability determination procedure due to intercell interference are required.

When subcarriers used for PI preamble transmission do not overlap between adjacent cells, even if the preamble sequence and paging indicator information used for generating the PI preamble are different from each other, there is no inter-cell interference.

The following describes the synchronization procedure and paging indicator detection procedure when the second PI preamble configuration method is used.

28 and 29 are diagrams illustrating a synchronization procedure and a paging indicator detection procedure of an idle mode mobile terminal using a PI preamble when a second PI preamble configuration scheme is used.

28 and 29, the idle mode mobile terminal receives a frame in the paging validity interval allocated to it (2801), and determines whether the received frame is a PI preamble or a traffic data symbol (2802).

If the received frame is a traffic data symbol, the idle mode mobile terminal determines whether data decoding is possible (2803), and if decoding is possible, decodes data (2804).

If the received frame is the PI preamble, the mobile terminal determines whether the idle mode, the active mode or the initial synchronization (2805).

In the idle mode, the mobile terminal performs frame detection and symbol timing acquisition using a symbol corresponding to a PI preamble (2806). After the timing synchronization is acquired, the idle mode mobile terminal estimates a carrier frequency offset (2807). The mobile terminal estimates a cell search or integer carrier frequency offset (CFO) (2808), and determines whether the base station is changed (2809). When the base station is changed, the mobile terminal decodes data for paging control information (2810). When the base station is not changed, the idle mode mobile terminal checks the reliability of the paging indicator (2811) and determines whether the reliability of the paging indicator is higher than the reference value (2812).

If it is determined that the reliability of the paging indicator is lower than the reference value, the mobile terminal acquires paging control information without performing paging indicator detection (2810). If the reliability of the paging indicator is higher than a reference value and determined to be a reliable level, the mobile terminal determines whether the paging indicator is on as a result of the paging indicator detection (2813), and if the paging indicator is on, paging control information Acquire (2810) and re-enter the idle mode (2814) when the paging indicator is off.

The initial synchronization mobile terminal acquires frame detection and symbol timing (2815), estimates carrier frequency offset (2816), estimates cell search or integer carrier frequency offset (2817), and performs DL broadcast control information and network entry. Data is decoded (2818).

The active mode mobile terminal acquires frame detection and symbol timing (2819), estimates a carrier frequency offset (2820), and determines whether handover is necessary (2821). If the handover is necessary, the active mode mobile terminal performs a handover procedure (2822). If the handover is not necessary, the active mode mobile terminal decodes data for DL broadcast control information and user data (2823).

The mobile terminal performs frame detection and symbol timing acquisition using a symbol corresponding to a PI preamble. After the timing synchronization is acquired, the idle mode mobile terminal estimates the carrier frequency offset. The paging indicator detection is performed after the synchronization process, and after detecting the paging indicator, the idle mode mobile terminal determines whether to perform the paging indicator detection by checking the reliability of the paging indicator. If it is determined that the reliability is low as a result of the reliability test of the paging indicator, the paging control information is obtained without performing the paging indicator detection, and the paging indicator detection is performed if the reliability is determined to be reliable. As a result of detecting the paging indicator, the paging control information is acquired when the paging indicator is on, and re-enters the idle mode when the paging indicator is off. Here, the timing and frequency tracking process is performed as necessary when acquiring the paging control information, which is not considered in FIGS. 28 and 29.

If the preamble sequence used for generating the PI preamble is designed for function of cell search or integer frequency offset estimation, the mobile terminal simultaneously performs cell search or integer frequency offset estimation and paging indicator detection using the PI preamble after the synchronization process. do. If it is determined that the cell has been changed after the cell search is performed, the paging control information is obtained to perform the idle handover and the position update.

If the preamble sequence used for generating the PI preamble is not a cell search sequence, the cell search is performed using the cell search preamble.If the cell is changed after determining whether to change the cell using the cell search result, the idle handover and Acquire paging control information to perform location update.

In the case of the PI preamble to which the second PI preamble sequence configuration method is applied, the paging indicator detection method using the phase of the correlation value and the paging indicator detection method using the size may be subdivided as in the case of the dedicated PI symbol. In some cases, paging indicator detection may be performed using both phase and magnitude.

The following shows an embodiment of a PI preamble sequence when the second PI preamble sequence configuration method is applied.

In Equation 20, paging indicator information is multiplied by an odd number of preamble sequence elements and transmitted. In Equation 21, the preamble sequence is transmitted through the real part, the paging indicator information is transmitted through the imaginary part, and only phase information is available when the paging indicator is detected.

31 and 32 illustrate a preamble structure of a second PI preamble sequence configuration method constructed using Equations 7 and 8.

이다. When the PI preamble is configured using Equation 20, BPSK modulated paging indicator detection is as follows. In this case, the number of subcarriers used for cross correlation

to be.

The cross-correlation procedure eliminates the need for channel estimation and compensation when detecting paging indicators. If there is an integer frequency offset in Equation 22, the paging indicator detection scheme is given as follows.

번째 페이징 인디케이터가 전송 되는 부반송파 그룹에서 셀 탐색, ICFO 검출 및 페이징 인디케이터 검출은 다음과 같이 주어진다.In the PI preamble transmission using Equation 23, cell search is performed through cross correlation of the received PI preamble and the preamble sequence.

Cell search, ICFO detection, and paging indicator detection in the subcarrier group in which the first paging indicator is transmitted are given as follows.

가 1 또는 -1인 경우 수학식 23은 다음과 같이 표현할 수 있다.In equation (24)

Is 1 or -1, Equation 23 can be expressed as follows.

When the paging indicator is transmitted by applying the second PI preamble sequence configuration method, the base station may transmit a preamble sequence corresponding to a different preamble index to distinguish each base station. In this case, in order to reduce performance degradation due to inter-cell interference when detecting paging indicators, cross-correlation characteristics between subcarrier groups used for transmission of each paging indicator should be good.

는 -1,

는 1을 전송하고, 페이징 인디케이터가 오프일 때

는 1,

는 -1을 전송한다면

번째 페이징 인디케이터가 전송되는 부반송파 그룹에 대한 셀 탐색, ICFO 검출 및 페이징 인디케이터 검출은 다음과 같다.When the PI preamble is generated using Equation 21, when the paging indicator is on

Is -1,

Transmits 1 and when the paging indicator is off

Is 1,

If it sends -1

Cell search, ICFO detection and paging indicator detection for the subcarrier group to which the first paging indicator is transmitted are as follows.

는 다른 기지국으로부터의 간섭이다.here,

Is interference from another base station.

In the second PI preamble sequence configuration method, when a neighboring base station uses the same subcarrier and preamble sequence for transmitting the PI preamble and configures the PI preamble as shown in Equation 20 and Equation 21, one sequence is detected when the paging indicator is detected using phase. If the paging indicator is distinguished from on / off by changing the phase information, the paging indicator detection performance is degraded due to inter-cell interference when different paging indicator information is transmitted from adjacent base stations. That is, when the same preamble sequence is used for all base stations, base stations belonging to the same paging zone transmit the same paging indicator information and thus are not affected by intercell interference, but two neighboring base stations belonging to different paging zones transmit different paging indicators. The paging indicator detection performance due to intercell interference is degraded. Inter-cell interference can be mitigated when different base stations use different preamble sequences with good correlation characteristics or sequences with good correlation characteristics to distinguish on / off of the paging indicator. In addition, when the on / off of the paging indicator is distinguished using a sequence having good correlation characteristics, or when neighboring base stations transmit dedicated PI symbols using different subcarriers, interference between adjacent cells can be mitigated. In the second PI preamble sequence configuration method, after detecting the paging indicator, the inter-cell interference and noise are estimated and the paging indicator reliability is determined to determine whether the paging control information is decoded. In the second PI preamble sequence configuration method, paging indicator detection is performed using the result of the correlation value, thereby reducing the effects of interference and noise when detecting the paging indicator. However, when performing cell search and paging indicator detection using correlation values after cross-correlation, more subcarriers are needed than in the first scheme to transmit one paging indicator. Therefore, when the idle mode mobile terminal that can be called simultaneously per frame and the number of subcarriers used in the preamble are determined, the number of paging indicators that can be distinguished is smaller than that of the first dedicated PI symbol configuration method when the second PI preamble sequence configuration method is used. Increases in size

If only one idle mode mobile terminal of the idle mode mobile terminal in the paging group is turned on, the idle mode mobile terminals of the idle mode mobile terminals in the same paging group do not have paging information. Since it is necessary to decode the power consumption reduction efficiency of the paging indicator is reduced. Therefore, the case in which the paging indicator uses the same subcarrier set to increase the number of paging indicators that can be transmitted using one PI preamble or to increase the length of a sequence for paging indicator transmission may be considered. In this case, paging indicators transmitted through the same subcarrier set must be distinguished using sequences having good cross-correlation characteristics.

As such, when the paging indicator transmission scheme and the idle mode mobile terminal paging procedure according to the present invention are applied to an OFDM-based mobile communication system, efficient paging can be performed compared to an OFDM-based mobile communication system that does not use a paging indicator. Idle mode can effectively reduce the power of the mobile terminal can increase the battery life of the mobile terminal.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the claims below but also by the equivalents of the claims.

1 is a diagram illustrating a configuration of a mobile communication system including an idle mode mobile terminal.

2 is a diagram illustrating an example of paging information for an idle mode mobile terminal.

3 is a diagram illustrating a frame structure when paging control information is transmitted over all frames.

4 is a diagram illustrating a frame structure when the frame control information exists within a few symbols of the beginning of the frame.

5 is a diagram illustrating an operation of a wireless modem of a mobile terminal when decoding paging control information.

6 is a diagram illustrating an operation of a wireless modem of an idle mode mobile terminal during a paging valid period when a paging indicator is applied.

7 is a diagram illustrating a frame structure when the paging indicator transmission scheme according to the first scheme is applied.

FIG. 8 is a diagram illustrating an operation of a wireless modem when detecting a synchronization and paging indicator when the paging indicator transmission method according to the first scheme is applied.

9 is a diagram illustrating a frame structure when the paging indicator transmission scheme according to the second scheme is applied.

FIG. 10 is a diagram illustrating an operation of a wireless modem when detecting a synchronization and paging indicator when the paging indicator transmission method according to the second scheme is applied.

11 is a diagram illustrating a frame structure when a paging indicator transmission scheme according to a third scheme is applied.

12 is a diagram illustrating an operation of a wireless modem when detecting a synchronization and paging indicator when the paging indicator transmission method according to the third scheme is applied.

13 is a diagram illustrating a frame structure when the paging indicator transmission scheme according to the fourth scheme is applied.

14 is a diagram illustrating an operation of a wireless modem when detecting a synchronization and paging indicator when the paging indicator transmission method according to the fourth scheme is applied.

15 is a diagram illustrating a concept of a dedicated PI symbol configuration in a paging indicator transmission method using a dedicated PI symbol.

16 is a diagram illustrating a concept of an on / off classification method of a paging indicator.

FIG. 17 is a diagram illustrating a case of using Equation 1 in a dedicated PI symbol configuration method according to the present invention.

18 is a diagram illustrating a case where Equation 3 is used in a dedicated PI symbol configuration method according to the present invention.

19 is a diagram illustrating a case in which Equation 4 is used in a dedicated PI symbol configuration method according to the present invention.

20 is a diagram illustrating a case of using equation (7) of the dedicated PI symbol configuration method according to the present invention.

21 is a diagram illustrating a case in which Equation 8 is used in a dedicated PI symbol configuration method according to the present invention.

22 is a diagram illustrating a case of using Equation 11 in the dedicated PI symbol configuration method according to the present invention.

FIG. 23 is a diagram illustrating a case where Equation 12 is used in a dedicated PI symbol configuration method according to the present invention.

24 illustrates a concept of a first PI preamble design according to the present invention.

25 illustrates a concept of a second PI preamble design according to the present invention.

26 and 27 illustrate a synchronization procedure and a paging indicator detection procedure of an idle mode mobile terminal using a PI preamble when using the first PI preamble configuration method according to the present invention.

28 and 29 are diagrams illustrating a synchronization procedure and a paging indicator detection procedure of an idle mode mobile terminal using a PI preamble when using a second PI preamble configuration method according to the present invention.

30 is a diagram illustrating a PI preamble configuration when Equation 15 is used.

FIG. 31 illustrates a PI preamble configuration when Equation 20 is used.

32 is a diagram illustrating a PI preamble configuration when Equation 21 is used.

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

510, 610, 810, 1010, 1210, 1410: synchronization unit

520, 630, 830, 1030, 1230, 1420: paging control information decoder

620, 1020, 1220: paging indicator detector

820: PICH decoder

Claims (24)

Obtaining, by the mobile terminal, a wake-up at a paging available interval allocated to the mobile terminal in an idle mode to perform paging indicator detection;  Acquiring paging control information when a serving base station of a current paging validity interval and a previous paging validity interval differs according to the synchronization acquisition result; Detecting a paging indicator corresponding to the mobile terminal group to which the mobile base station belongs to the serving base station of the current paging valid period and the previous paging valid period according to the synchronization acquisition result; And Determining whether to obtain paging control information using the detected paging indicator Paging indicator detection method comprising a. The method of claim 1, And transmitting the paging indicator to the serving base station by using a paging indicator symbol, which is a data transmission symbol including a subcarrier for transmitting a paging indicator. The method according to claim 1 or 2, Acquiring synchronization by using the preamble after waking up from a paging valid interval allocated to the mobile terminal in an idle mode; Decoding the paging control information when a serving base station of the current paging validity interval and the previous paging validity interval is different according to the synchronization acquisition result; Determining a paging indicator detection reliability when the serving base station of the current paging valid period and the previous paging valid period are the same; Obtaining paging control information when the paging indicator detection reliability is less than a reference value; Detecting a paging indicator using a partial fast fourier transform when the paging indicator detection reliability is equal to or greater than a reference value; And Determining paging control information detection or idle mode re-entry depending on whether the paging indicator is on or off. Paging indicator detection method further comprising. The method of claim 1, Transmitting the paging indicator to the serving base station using a dedicated PI symbol for the paging indicator transmission. The method according to claim 1 or 4, Acquiring synchronization using a preamble after waking from a paging valid period allocated to the mobile terminal in an idle mode; Decoding paging control information when a serving base station of a current paging valid period and a previous paging valid period is different according to the synchronization acquisition result; Determining a paging indicator detection reliability using dedicated PI symbol interference when the serving base station of the current paging validity interval and the previous paging validity interval is the same; Obtaining paging control information when the paging indicator detection reliability is less than a reference value; And Determining paging control information detection or idle mode re-entry according to on / off of the paging indicator when the paging indicator detection reliability is equal to or greater than a reference value. Paging indicator detection method further comprising. The method according to claim 2 or 4, Discriminating on / off of the paging indicator by using the position, phase, sequence of paging indicators of a symbol or power transmitted on a designated subcarrier of a symbol when constructing a PI symbol. The method of claim 1, And transmitting the paging indicator to the serving base station using a PI preamble in which paging indicator information is added to a preamble. The method of claim 1, Acquiring frame detection, timing, and carrier frequency offset synchronization using a PI preamble after waking up from a paging valid period allocated to the mobile terminal in an idle mode; Searching for a cell using the PI preamble when a cell search using a PI preamble is required; Decoding paging control information when a serving base station of a current paging valid period and a previous paging valid period is different according to the synchronization acquisition result; Detecting a paging indicator using a PI preamble when the current paging validity interval and the previous paging validity interval are the same; Determining paging indicator detection reliability using noise and inter-cell interference after detecting the paging indicator; Obtaining paging control information when the paging indicator detection reliability is less than a reference value; And Determining paging control information detection or idle mode re-entry according to on / off of the paging indicator when the paging indicator detection reliability is equal to or greater than a reference value. Paging indicator detection method further comprising. The method of claim 8, A paging indicator detection method further comprising the step of distinguishing a paging indicator on / off using binary phase shift keying, differential binary phase shift keying, or a paging indicator sequence. 10. The method of claim 9, And configuring a PI preamble considering cell search and integer carrier frequency offset estimation when the paging indicator is on / off using the binary phase shift modulation method or the differential binary phase shift modulation method. . 10. The method of claim 9, And configuring a PI preamble in consideration of cell search and integer frequency offset when distinguishing on / off of a paging indicator using the paging indicator sequence. The method of claim 10, Configuring the PI preamble is In case of distinguishing ON / OFF of a paging indicator using the binary phase shift modulation method or the differential binary phase shift modulation method, two adjacent subcarriers among subcarriers used in the PI preamble for cell search and integer carrier frequency offset estimation are used. A paging indicator detection method for forming a PI preamble by multiplying by the same paging indicator. The method of claim 11, Configuring the PI preamble is When the paging indicator is distinguished from the on / off using the paging indicator sequence, a PI preamble is configured by multiplying a sequence known to all idle mode mobile terminals for cell search and integer carrier frequency offset estimation. The method of claim 8, The determining of the paging indicator detection reliability may include: If there is no inter-cell interference, determining paging indicator detection reliability considering only noise; or Determining the paging indicator detection reliability in consideration of noise and intercell interference when intercell interference exists Paging indicator detection method comprising a. The method of claim 14, The determining of the paging indicator detection reliability may include: And determining paging indicator detection reliability using noise estimated using a preamble or noise estimated using a dedicated PI symbol. The method of claim 14, The determining of the paging indicator detection reliability may include: Paging indicator for determining the paging indicator detection reliability by using the inter-cell interference estimated using the cell search results or when each base station uses a different dedicated PI symbol sequence, using the estimated inter-cell interference using the dedicated PI symbol. Detection method. A synchronization unit for acquiring a synchronization for performing paging indicator detection by waking up at a paging available interval allocated to the user in an idle mode;  A paging control information obtaining unit for obtaining paging control information when a serving base station of a current paging valid period and a previous paging valid period is different according to the synchronization acquisition result; A paging indicator detector for detecting a paging indicator corresponding to the mobile terminal group to which the mobile base station belongs to the same when the serving base station of the current paging valid period and the previous paging valid period is the same according to the synchronization acquisition result; And Determination unit for determining whether to obtain paging control information by using the detected paging indicator Paging indicator detection device comprising a. The method of claim 17, And a paging control information decoder which decodes the paging control information when a serving base station of the current paging validity interval and the previous paging validity interval is different according to the synchronization acquisition result. The determination unit, If the serving base station of the current paging valid period and the previous paging valid period is the same, the paging indicator detection reliability is determined, The paging control information acquisition unit, If the paging indicator detection reliability is less than a reference value, obtain paging control information, The paging indicator detector, When the paging indicator detection reliability is greater than or equal to a reference value, a paging indicator is detected by using a partial fast fourier transform, The determination unit, And a paging indicator detection device for determining paging control information detection or idle mode re-entry depending on whether the paging indicator is on or off. The method of claim 17, A paging control information decoding unit for decoding paging control information when the serving base station of the current paging valid period and the previous paging valid period is different according to the synchronization acquisition result; The determination unit, When the serving base station of the current paging validity interval and the previous paging validity interval is the same, the paging indicator detection reliability is determined using dedicated PI symbol interference, The paging control information acquisition unit, If the paging indicator detection reliability is less than a reference value, obtain paging control information, The determination unit, And determining paging control information detection or idle mode reentry according to on / off of the paging indicator when the paging indicator detection reliability is equal to or greater than a reference value. The method of claim 17, The synchronization unit, After waking up from the paging valid period assigned to the idle mode in the idle mode, frame detection, timing, and carrier frequency offset synchronization are acquired using a PI preamble, and a cell using the PI preamble is needed when performing cell searching using a PI preamble. Explore, The paging control information decoding unit, If the serving base station of the current paging valid period and the previous paging valid period is different according to the synchronization acquisition result, decode the paging control information; The paging indicator detector, If the current paging valid period and the previous paging valid period is the same, the paging indicator is detected using a PI preamble, The determination unit, After detecting the paging indicator, using the noise and inter-cell interference to determine the paging indicator detection reliability, The paging control information acquisition unit, If the paging indicator detection reliability is less than a reference value, obtain paging control information, The determination unit, And a paging indicator detection device for determining paging control information detection or idle mode re-entry according to on / off of the paging indicator when the paging indicator detection reliability is equal to or greater than a reference value. The method according to any one of claims 18 to 20, The determination unit, Paging indicator detection device for determining the on / off of the paging indicator by using the position, phase, the sequence of the paging indicator of the symbol, or the power transmitted to the designated subcarrier of the symbol when configuring the PI symbol. The method according to any one of claims 18 to 20, The determination unit, Determining the paging indicator detection reliability using noise estimated using a preamble or noise estimated using a dedicated PI symbol, using estimated intercell interference using a cell search result, or each base station uses a different dedicated PI When using a symbol sequence, the paging indicator detection apparatus for determining the paging indicator detection reliability by using the inter-cell interference estimated using the dedicated PI symbols. The method of claim 20, The PI preamble, In case of distinguishing ON / OFF of a paging indicator using the binary phase shift modulation method or the differential binary phase shift modulation method, two adjacent subcarriers among subcarriers used in the PI preamble for cell search and integer carrier frequency offset estimation are used. And a paging indicator multiplied by the same paging indicator. The method of claim 20, The PI preamble, And a paging indicator detection apparatus configured to multiply a sequence known to all idle mode mobile terminals for cell searching and integer carrier frequency offset estimation when the paging indicator sequence is on / off using the paging indicator sequence.

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