KR20110002440A - Method of perfomring paging in wireless communication system - Google Patents

Abstract

PURPOSE: A method of performing paging in a wireless communication system is provided to smoothly perform paging through a message while transferring the information of a paging group supported by a base station. CONSTITUTION: A base station supports entire paging groups, and transmits a paging message to at least one mobile station in every paging section(S410). The paging message includes identifier information for each panging group. If the paging message includes an identifier for at least one terminal, the base station receives a paging response message from at least one terminal(S420).

Description

How to perform paging in a wireless communication system {Method Of perfomring paging in wireless communication system}

The present invention relates to wireless communications, and more particularly, to a method of performing paging.

3rd Generation Partnership Project (3GPP) long term evolution (LTE) and Institute of Electrical and Electronics Engineers (IEEE) 802.16m are being developed as candidates for the next generation wireless communication system. The 802.16m specification implies two aspects: past continuity, a modification to the existing 802.16e specification, and future continuity, a specification for the next generation of IMT-Advanced systems. Accordingly, the 802.16m standard requires all the advanced requirements for the IMT-Advanced system to be maintained while maintaining compatibility with the Mobile WiMAX system based on the 802.16e standard.

Wireless communication systems generally use one bandwidth for data transmission. For example, the second generation wireless communication system uses a bandwidth of 200KHz ~ 1.25MHz, the third generation wireless communication system uses a bandwidth of 5MHz ~ 10MHz. In order to support increasing transmission capacity, recent 3GPP LTE or 802.16m continues to expand its bandwidth to 20 MHz or more. In order to increase the transmission capacity, it is necessary to increase the bandwidth. However, even when the level of service required is low, supporting a large bandwidth can cause a large power consumption.

Paging refers to a function of identifying a corresponding terminal when an incoming call occurs in mobile communication. When the base station sends a paging message to the terminal, the terminal sends a paging response message thereto. The paging message for paging may be included in the superframe header and transmitted. However, the space available to the superframe header is very limited so that all information desired cannot be loaded. In addition, when there are a plurality of paging groups supported by the base station, a problem may occur in that all paging group identifiers cannot be included in the superframe header.

In addition, the existing paging limits the range of the identifier of the terminal to be paged in the paging group to reduce the overhead of the paging message. In this case, if the base station supports multiple paging groups, the terminal cannot be identified only by the identifier of the terminal, and the terminal can be identified only when the paging group identifier and the terminal identifier are used together. Re-incorporating the paging group identifier in the paging message to identify the terminal may cause a problem of increasing the overall system overhead even if the identifier list of the paging group supported by the base station has already been transmitted in the superframe in which the paging message is transmitted.

An object of the present invention is to provide a method for efficiently paging a terminal by transmitting paging group information supported by a base station.

According to an aspect of the present invention, a method of performing paging by a base station in a wireless communication system includes paging group including identifier information of a paging group supported by the base station among a paging group which is a group of at least one terminal to be paged in the same paging interval. Transmitting a message in a paging segment and receiving a paging response message from the at least one terminal if the paging message includes an identifier for the at least one terminal.

Paging can be performed more flexibly than a conventional method by transmitting paging group information supported by a base station using a paging message and simultaneously performing paging.

In addition, system overhead can be reduced compared to the conventional method of separating paging group information and paging procedure separately.

1 is a block diagram illustrating a wireless communication system.
2 shows an example of a frame structure.
3 shows a general paging method.
4 and 5 illustrate a paging process according to the present invention.
6 illustrates an embodiment of a paging message transmission when a base station supports a paging group supporting different paging segments.
7 illustrates a method of updating a location of a terminal according to the present invention.
8 illustrates a time point for transmitting a paging message, according to the present invention.

Hereinafter, some embodiments will be described in detail with reference to the accompanying drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible even though they are shown in different drawings. In addition, in describing the embodiments of the present specification, when it is determined that a detailed description of a related well-known configuration or function may obscure the gist of the present specification, the detailed description thereof will be omitted.

In addition, in describing the component of this specification, terms, such as 1st, 2nd, A, B, (a), (b), can be used. These terms are only for distinguishing the components from other components, and the nature, order or order of the components are not limited by the terms.

The following technologies include code division multiple access (CDMA), frequency division multiple access (FDMA), time division multiple access (TDMA), orthogonal frequency division multiple access (OFDMA), single carrier-frequency division multiple access (SC-FDMA), and the like. Such as various wireless communication systems. CDMA may be implemented with a radio technology such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented with wireless technologies such as Global System for Mobile communications (GSM) / General Packet Radio Service (GPRS) / Enhanced Data Rates for GSM Evolution (EDGE). OFDMA may be implemented in a wireless technology such as IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802-20, Evolved UTRA (E-UTRA). UTRA is part of the Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) long term evolution (LTE) is part of an Evolved UMTS (E-UMTS) using E-UTRA, and employs OFDMA in downlink and SC-FDMA in uplink.

1 is a block diagram illustrating a wireless communication system. Wireless communication systems are widely deployed to provide various communication services such as voice, packet data, and the like.

Referring to FIG. 1, a wireless communication system includes a user equipment (UE) 10 and a base station 20 (BS). The terminal 10 may be fixed or mobile and may be called by other terms such as mobile station (MS), advanced mobile station (AMS), user terminal (UT), subscriber station (SS), and wireless device (wireless device). have. The base station 20 generally refers to a fixed station communicating with the terminal 10, and includes an advanced base station (ABS), a node-b (node-b), a base transceiver system (BTS), and an access point ( Access Point) may be called. One or more cells may exist in one base station 20.

Hereinafter, downlink (DL) means communication from the base station 20 to the terminal 10, and uplink (UL) means communication from the terminal 10 to the base station 20. In downlink, the transmitter may be part of the base station 20 and the receiver may be part of the terminal 10. In uplink, the transmitter may be part of the terminal 10 and the receiver may be part of the base station 20. For clarity, the following description focuses on IEEE 802.16m, but the technical spirit of the present invention is not limited thereto.

2 shows an example of a frame structure.

Referring to FIG. 2, a superframe includes a superframe header and four frames Frame0 to Frame3. In the case of using a superframe, the transmission period of control information that does not need to be transmitted frequently can be increased in units of superframes, thereby increasing the efficiency of transmission. In addition, data allocation and scheduling are most frequently performed in subframe units, thereby reducing delay characteristics of data transmission considering a retransmission mechanism. The size of each superframe is 20ms and the size of each frame is illustrated as 5ms, but is not limited thereto.

The superframe header may be placed at the front of the superframe, and a common control channel is assigned. The common control channel is a channel used for transmitting control information that can be commonly used by all terminals in a cell, such as information on frames or system information of a superframe. The superframe header includes a primary superframe header (P-SFH) and a secondary superframe header (S-SFH).

The main superframe header is included in the first frame of each superframe, and the main superframe header is configured as shown in the table below.

Syntax Size (bit) LSB of Superframe Number 4 S-SFH Change Count 4 S-SFH Size 4 S-SFH Transmission Format 2 S-SFH Scheduling Information bitmap 3 S-SFH SP Change Bitmap 3 Reserved 4

The primary superframe header is included in every superframe and indicates whether the auxiliary superframe included in the current superframe is included and the update number of system information supported by the current superframe.

The secondary superframe header is divided into three secondary superframe header subpackets (S-SFH SP) according to their characteristics, and each secondary superframe header subpackets are required for the mobile terminal to access the base station. Is used to broadcast the system information to the mobile terminal. Each auxiliary superframe header subpacket may be transmitted according to a different transmission period according to the nature of the included system information. For example, the auxiliary superframe header subpacket 1 may be transmitted in 2 superframe periods, the auxiliary superframe header subpacket 2 in 3 superframe periods, and the auxiliary superframe header subpacket 3 in 4 superframe periods.

One frame includes eight subframes (Subframe, SF0, SF1, SF2, SF3, SF4, SF5, SF6, SF7). Each subframe may be used for uplink or downlink transmission. The subframe may consist of 6 or 7 OFDM symbols, but this is only an example. Time division duplexing (TDD) or frequency division duplexing (FDD) may be applied to the frame. In TDD, each subframe is used in uplink or downlink at different times at the same frequency. That is, subframes in the TDD frame are divided into an uplink subframe and a downlink subframe in the time domain. In FDD, each subframe is used as uplink or downlink on a different frequency at the same time. That is, subframes in the FDD frame are divided into an uplink subframe and a downlink subframe in the frequency domain. Uplink transmission and downlink transmission occupy different frequency bands and may be simultaneously performed.

3 shows a general paging method.

According to FIG. 3, information of a paging group supported by a base station is broadcast in a specific S-SFH Service Packet (SP). Accordingly, the S-SFH SP is broadcasted according to the paging period of the terminal, and this information is transmitted regardless of whether the terminal is paged.

On the other hand, the paging message is transmitted according to the paging period when the terminal is paged. The interval in which the paging message is transmitted is called a paging interval and may also be called a paging listening interval. The paging message was not transmitted because no paging occurred in the first paging segment, and the paging message was transmitted because paging occurred in the second paging segment. In this case, the transmitted paging message includes an identifier of a paging group where paging occurs and an identifier of a terminal paged in each paging group.

The space available to the P-SFH or S-SFH is so limited that it cannot carry all the desired information. In addition, when there are a plurality of paging groups supported by the base station, a problem may occur in that all paging group identifiers cannot be included in the S-SFH.

In addition, the existing paging limits the range of the identifier of the terminal to be paged in the paging group to reduce the overhead of the paging message. In this case, if the base station supports multiple paging groups, the terminal cannot be identified only by the identifier of the terminal, and the terminal can be identified only when the paging group identifier and the terminal identifier are used together. Re-incorporating the paging group identifier in the paging message to identify the terminal may cause a problem of increasing the overall system overhead even if the identifier list of the paging group supported by the base station has already been transmitted in the superframe in which the paging message is transmitted.

Hereinafter, a paging method according to the present invention will be described.

4 and 5 illustrate a paging process according to the present invention.

According to FIGS. 4 and 5, a paging message including identifier information 50 of each paging group supported by the base station among paging groups, which is a group of at least one terminal paged in the same paging segment, is transmitted every paging segment. (S410). The paging message is transmitted every paging interval regardless of whether paging is performed, and the paging group identifier information supported by the base station is included in the paging message rather than the S-SFH. Paging does not occur in the first paging segment, so the paging message includes only the paging group identifier information 50 supported by the base station. In the second paging segment, paging occurs, not only the paging group identifier supported by the base station, but also the paging group identifier. It also includes an identifier 55. In addition, even if paging does not occur, paging group identifier information such as PGID2 is included in a paging message every paging interval. From the system point of view, the overhead required to manage paging in every paging cycle remains the same regardless of whether or not paging is present. There is an effect that does not occur. The paging segment may be in a superframe unit, and the paging message may be transmitted in any frame in the superframe. Subsequently, when the paging message includes an identifier for the at least one terminal, a paging response message is received from the at least one terminal (S420).

Since the space available to the superframe header is very limited, the space available to the paging message is larger, so that paging group identifier information or a list of identifiers of the terminal can be loaded, and the paging group supported by the base station can also be used. In many cases, all paging group identifiers can be included in the paging message.

In addition, since a paging group identifier is included in every paging message, even if the base station supports multiple paging groups, the terminal can be identified by including the identifier of the terminal, so that the paging group identifier and the terminal identifier do not need to be used together. Resolve the problem of increasing the overall system overhead by including the paging group identifier in the paging message again to identify the terminal even though the paging group identifier list supported by the base station has already been transmitted in the superframe where the paging message is transmitted in the existing paging. Can be.

Table 2 shows the format of a paging message for performing paging according to the present invention. Among the parameters included in the paging message, N_PG_ID indicating the number of paging group identifiers, PGID as the paging group identifier, and N_AMS indicating the number of terminals where paging has occurred are included in the paging message every paging cycle regardless of whether paging is present. If paging does not occur, the N_AMS value becomes 0. If paging occurs, the value of N_AMS is set as the number of paging groups for each paging group, and each terminal includes a TempID and an action code for each terminal. do.

Parameters Note N_PG_ID Number of PG ID (s) For (i = 0, i <N_PG_ID, i ++) { PG ID Paging Group ID corresponding to the current paging listening interval N_AMS Number of AMSs For (j = 0, j <N_AMS, j ++) { TempID Temporary identifier of an AMS Action code 0b00: Perform network re-entry
0b01: Perform ranging to establish location
0b10: Perform LBS measurement } }

6 illustrates an embodiment of a paging message transmission when a base station supports a paging group supporting different paging segments.

In the paging scheme according to the present invention, identifiers of all paging groups supported by the base station are included in one paging message and are not transmitted every paging segment. The paging group may be set in a network, where each paging group may have a different paging period and paging segment for each paging group. In this case, only the identifier of the paging group supporting each paging segment is included in the paging message. The base station supports two paging groups, and each paging group has the same paging period, but the paging segment is managed differently and distinguished by an offset.

Since the first paging segment is a paging segment supported by PGID1, only the PGID1 is included in the paging message transmitted at this time. Since the second paging segment is a paging segment supported by PGID2, only the PGID2 is included in the paging message transmitted at this time. The third paging segment is a segment supported by PGID1. Since paging occurs, the identifier of the PGID1 and the paged terminal is included in the paging message. In the fourth paging segment, like the second paging segment, the paging segment is supported by PGID2, and since no paging occurs, only the PGID2 is included in the paging message.

7 shows a location update method of a terminal according to the present invention.

In the mobile communication network, since the terminal continues to move, the base station must keep track of the exact location and related information of each terminal at the network side. The updating function of such location information is called a location update. In addition, even if the terminal stays in one position without moving, if paging does not occur for a long time, the base station cannot determine whether the terminal is normally performing idle mode operation in the network. Therefore, even if the current location has not changed, the terminal should perform location update every predetermined time. The terminal in the idle mode performs the location update process when the location update trigger condition is satisfied. There are paging group based updates, timer based updates, power down updates and MBS updates. In addition, the terminal may arbitrarily perform location update.

According to FIG. 7, when a terminal enters another paging group while moving to an idle mode, the terminal needs to register a current location, and recognizes that the paging group is different by receiving paging group information transmitted by the base station. Since the paging group information supported by the base station is transmitted through the paging message, the mobile station should receive the paging message every paging interval.

In case of mobile terminal 1, an attempt was made to receive a paging message in a paging segment, but the paging message was not transmitted from the base station. In this case, the mobile station 1 assumes that the base station does not transmit the paging message because the base station does not support the paging group supported by the mobile station 1 and performs the location update procedure immediately.

The mobile terminal 2 receives a paging message from the base station in the paging segment, but does not include the identifier of the paging group supported by the mobile terminal 2 in the paging message. In this case, the mobile station 2 receives the paging message, but since there is no identifier of the paging group supported by the mobile station 2 in the paging message, it is determined that the base station currently does not support the paging group supported by the mobile station 2 to update the location immediately Perform the procedure.

8 illustrates a time point for transmitting a paging message, according to the present invention.

According to FIG. 8, a paging message may be transmitted in any frame within a paging segment. However, the paging message may be transmitted in a specific frame within the paging interval, and in this case, the terminal may decide to resume the idle mode immediately after receiving the specific frame.

The transmission time of the paging message is not limited as shown in FIG. 8, but is only an example of a specific frame. The transmission time of the paging message may be operated with the same value in the system, or may be set to different values for each terminal through message exchange when entering the idle mode. The terminal may not perform decoding of the downlink signal from the start frame of the paging segment to the frame in which the predetermined paging message is transmitted, and immediately after receiving the paging message in the predetermined paging message transmission frame according to the parameter value included in the message. It may be determined to resume the idle mode and update the position.

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

Claims (9)

In the method for the base station performs paging,
Transmitting a paging message for each paging segment including identifier information of each paging group supported by the base station among paging groups that are groups of at least one terminal to be paged in the same paging segment; And
If the paging message includes an identifier for the at least one terminal, receiving a paging response message from the at least one terminal. The method of claim 1,
The paging message is transmitted at an offset position specifying the paging segment, The method of claim 2,
The offset is determined individually for each paging group identifier. The method of claim 1,
If the terminal cannot receive the paging message in the paging segment, the terminal performs a location update procedure, The method of claim 1,
If the terminal receives the paging message in the paging interval, but the paging message does not include an identifier of the paging group supported by the terminal, performing a location update procedure, The method of claim 1,
The terminal transmits the paging message in a specific frame within the paging interval, The method according to claim 6,
Without decoding the downlink signal from the start frame of the paging segment to the specific frame,
Determining whether to resume the idle mode according to a parameter value included in the paging message or performing a location update procedure immediately after the paging message is transmitted in the specific frame; The method of claim 1,
The size of the paging segment is one superframe, In the method in which the terminal performs paging,
Receiving a paging message for each paging segment including identifier information of each paging group supported by the base station among paging groups that are groups of at least one terminal to be paged in the same paging segment; And
If the paging message includes an identifier for the at least one terminal, the at least one terminal comprising transmitting a paging response message.

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