WO2012161511A2

WO2012161511A2 - Wireless lan ap searching method for vertical handoff to a wireless lan in a mobile communication network and a compact, mobile communication base station beacon apparatus therefor

Info

Publication number: WO2012161511A2
Application number: PCT/KR2012/004068
Authority: WO
Inventors: 김혜숙
Original assignee: Kim Hye Sook
Priority date: 2011-05-23
Filing date: 2012-05-23
Publication date: 2012-11-29
Also published as: WO2012161511A3; KR101105646B1

Abstract

The present invention relates to a method for accurately detecting an available wireless local area network access point (LAN AP) through a typical procedure for searching for an adjacent mobile communication base station, wherein the procedure uses a beacon of a mobile communication base station which transmits a signal from a compact beacon apparatus of a mobile communication base station having identical coverage as that of a wireless LAN AP, instead of a terminal directly searching for a beacon signal of a wireless LAN AP, and relates to a compact beacon apparatus of a mobile communication base station for the method. According to the present invention, the existence of the wireless LAN AP can be determined through the procedure for searching for an adjacent base station in a mobile communication network, thus preventing the waste of wireless resources as compared with conventional methods for searching for a wireless LAN AP. Further, according to the present invention, vertical handoff to a wireless LAN AP may be performed in a stable manner, thus minimizing power consumption in a terminal and also preventing handoff delay to thereby provide high quality service.

Description

WLAN AP discovery method for vertical handoff from mobile communication network to wireless LAN and small mobile communication base station beacon device for same

The present invention relates to a method for minimizing terminal power consumption required for searching for a WLAN AP and minimizing quality of service due to handoff during a vertical handoff from a mobile communication network to a wireless LAN. Through a mobile communication base station beacon transmitted by a small mobile communication base station beacon device having the same coverage as the wireless LAN AP, the terminal does not directly search for a beacon signal of the wireless LAN AP, but through the conventional mobile communication neighbor base station discovery procedure available WLAN A method for accurately detecting an AP and a small mobile communication base station beacon device therefor.

Recently, the traffic of mobile communication networks has exploded due to the proliferation of mobile Internet devices such as smartphones, tablet PCs, and netbooks. To cope with this problem, mobile operators can reduce cell size to increase base station density or increase frequency by additionally allocated frequency band, limit traffic of heavy traffic users when overloaded, WLAN It is using a method of offloading traffic.

Among the above methods, the method of distributing traffic to the WLAN is expected to be the most effective method because the cost is lower and the capacity increase effect is higher than other methods, but the actual effect is due to the issue of vertical handoff from the mobile communication network to the WLAN. Is not meeting expectations.

The most issues in the vertical handoff from the mobile communication network to the WLAN are the WLAN access point (AP) discovery method and IP mobility management protocol.

As the IP mobility management protocol, there are already well-established methods such as Dual Stack Mobile IP (DSMIP), Proxy Mobile IP (PMIP), and IP Flow Mobility.However, there is no effective method for WLAN AP discovery yet. have.

A typical WLAN AP discovery method is for a terminal to always search for a WLAN AP. However, in consideration of the fact that most APs are constructed in the form of hotspots, this method has a disadvantage in that the battery consumption of the terminal is too high.

In a more advanced manner, there is a method of informing a terminal of location information of a WLAN AP through a mobile communication network so that the terminal searches for the WLAN AP only in an area where the WLAN AP is located. In this method, since the UE can know exactly whether there is a WLAN AP available around the current location, there is an advantage that the WLAN module can be turned on only when necessary, but the location information of the WLAN AP in the terminal The radio resources of the mobile communication network are wasted in order to inform the problem, and the terminal battery consumption is still large because the GPS receiver of the terminal must be operated at all times.

The most advanced form of the present method is to inform the terminal of density information of the WLAN AP through the mobile communication network and to allow the terminal to adjust the WLAN AP discovery period according to the density of the WLAN AP. In this method, the WLAN AP can be relatively energy-efficient, but the radio resources are wasted to inform the UE AP density information, and it is difficult to discover the WLAN AP in an area where the WLAN AP density is low. There is this.

Therefore, there is a need for a method that overcomes the above problems and can efficiently search for a WLAN AP.

In order to solve the above problems, the present invention provides a WLAN AP discovery method for reducing terminal power consumption and minimizing quality degradation due to handoff delay in providing a vertical handoff function from a mobile communication network to a wireless LAN. There is a purpose.

In addition, an object of the present invention is to provide a small mobile communication base station beacon apparatus that can implement the above energy efficient WLAN AP discovery method at low cost.

The WLAN AP discovery method for a vertical handoff from the mobile communication network to the WLAN in accordance with the present invention designed to achieve the above object, the small mobile communication base station beacon device to inform the presence of the WLAN AP The first step of transmitting a specific cell identifier assigned to itself in advance through a beacon channel consisting of some of the channels used in the radio access technology of the mobile communication network, the terminal searches for a typical neighbor cell of the mobile communication network A second step of detecting the specific cell identifier through a procedure; and preventing the terminal from being handed off to the small mobile communication base station beacon apparatus based on the specific cell identifier in a normal neighbor cell search procedure of the mobile communication network; In step 3, the UE discovers the WLAN AP through the WLAN AP discovery procedure and performs a vertical handoff to the WLAN AP. al handoff).

In this case, the beacon channel may consist of only a pilot channel, a pilot channel and a synchronization channel, or a pilot channel, a synchronization channel and some control channels. The specific cell identifier may be a Cell-ID transmitted through a PN offset or a synchronization channel.

In addition, the small mobile communication base station beacon device may be implemented as a device independent from the WLAN AP, or may be implemented as an integrated device with the WLAN AP and may share some modules with the WLAN AP.

In addition, the second step may further include determining that there is a WLAN AP available nearby when the signal strength corresponding to the specific cell identifier is greater than or equal to a threshold.

On the other hand, in the third step, the terminal may recognize the specific cell identifier and prevent the handoff by not reporting the strength of the specific cell identifier or a signal corresponding thereto to the mobile communication base station. .

In addition, the third step may be characterized in that the mobile communication base station recognizes the specific cell identifier, thereby preventing the handoff by ignoring the specific cell identifier or the signal strength corresponding thereto.

In addition, in the first step, when the control channel is included in the beacon channel, the small mobile communication base station beacon apparatus transmits control information for preventing handoff, and in the third step, the terminal transmits the control information. On the basis of this, it may be characterized in that no handoff is attempted to the small mobile base station beacon apparatus.

In the second step, the terminal reports a specific cell identifier and a corresponding signal strength to a mobile communication base station through a mobile communication neighbor cell search procedure, and if the signal strength of the mobile communication base station is greater than or equal to a predetermined threshold, The method may further include reporting to a vertical handoff control server. The fourth step may include a vertical transmission to the WLAN AP when the terminal receives a message for detecting the WLAN AP corresponding to the specific cell identifier from the vertical control server. Handoff may be performed.

A small mobile communication base station beacon apparatus for WLAN AP discovery for vertical handoff from a mobile communication network according to the present invention devised to achieve the above object includes a specific cell identifier assigned for WLAN AP discovery. A digital signal processing unit for generating a digital signal, and converts the digital signal of the digital signal processing unit into an analog signal, and then to a transmission frequency, amplified to a predetermined signal strength and the coverage corresponding to the coverage of the corresponding WLAN AP through the antenna And a control unit for controlling the digital signal processor and the beacon transmitter and providing a timing and frequency reference signal.

In this case, the apparatus may further include a plurality of digital signal processing units supporting a plurality of different mobile communication technologies, and may further include a plurality of beacon transmitters supporting different frequency assignments or frequency bands.

In addition, the digital signal processing unit and the beacon transmitter may support a method of continuously transmitting a beacon signal or a method of transmitting at a predetermined interval.

In addition, when applied to a technology that requires network synchronization between base stations to search for neighboring base stations of mobile communication, the terminal may further include a synchronization receiving unit configured of any one of a GPS reception module, a base station forward channel reception module, and an IEEE 1588 synchronization reception module. .

According to the present invention, it is possible to determine the existence of the WLAN AP through the conventional neighbor base station discovery procedure in the mobile communication network to prevent the waste of radio resources compared to the conventional WLAN AP discovery method, and stable vertical hand to the WLAN AP By performing the off, it is possible to minimize the power consumption of the terminal and at the same time prevent the handoff delay to provide a high quality service.

In addition, the present invention provides an energy efficient WLAN AP discovery method for the vertical handoff from the mobile communication network to the wireless LAN to maximize the traffic distribution effect of the mobile communication network through the WLAN.

In particular, there is no need for the user to manually turn on / off the wireless LAN module of the terminal due to fear of terminal battery consumption, and provides high-speed communication by performing vertical handoff to the wireless LAN automatically where the wireless LAN AP is located. It has the effect of improving the quality of service.

1 is a diagram illustrating a network structure to which a small mobile communication base station beacon apparatus according to the present invention is applied.

2 is a flowchart illustrating a case where a terminal independently discovers a WLAN AP according to the present invention.

3 is a procedure of a method for notifying a terminal by determining whether or not a vertical handoff from a mobile communication network to a WLAN AP.

4 is a block diagram of a small mobile communication base station beacon device according to the present invention.

5 is a block diagram of a small mobile communication base station beacon device supporting a plurality of mobile communication technologies according to the present invention.

In order to achieve the above object, in the present invention, instead of directly searching for the beacon signal of the WLAN AP through the mobile communication base station beacon transmitted by the small mobile communication base station beacon apparatus having the same coverage as the WLAN AP (Access Point) It is possible to accurately detect available WLAN APs through a conventional mobile communication neighbor base station discovery procedure, thereby minimizing terminal power consumption required for WLAN AP discovery during vertical handoff from the mobile communication network to the WLAN and quality of service due to handoff. Provided are a method for minimizing degradation and a small mobile communication base station beacon device therefor.

1 shows a typical network structure to which a small mobile communication base station beacon apparatus according to the present invention is applied. In the drawings,

reference numerals

101 and 102 denote coverages of a mobile communication base station and a mobile communication base station, respectively, and

reference numerals

103 and 104 denote coverages of a WLAN AP and a WLAN AP, respectively.

Reference numerals

105 and 106 denote small mobile communication base station beacon apparatuses and their coverage according to the present invention, and reference numeral 107 denotes a mobile communication terminal.

As can be seen from the figure, the small mobile communication base station beacon device 105 is designed to have almost the same coverage as the WLAN AP 103 and transmits to the corresponding beacon channel according to the applied mobile communication technology. In this case, a specific cell identifier allocated for WLAN AP discovery is transmitted through the beacon channel.

For example, when synchronous code division multiple access (CDMA) technology is applied, the small mobile communication base station beacon device 105 transmits a PN offset (PN_Offset) to a specific cell identifier allocated for WLAN AP discovery through a pilot channel. When the Universal Mobile Telecommunication System (UMTS) technology is applied, the Cell-ID is transmitted to a specific cell identifier allocated for WLAN AP discovery through a Primary Synchronization Channel (P-SCH) and a Secondary Synchronization Channel (S-SCH). do.

Meanwhile, the beacon channel of the small mobile communication base station beacon apparatus 105 according to the present invention may include a cell common control channel for transmitting cell configuration information. For example, the beacon channel of the small mobile communication base station beacon device 105 for UMTS additionally includes a primary common control physical channel (PCCPCH), so that the terminal is a small mobile communication base station beacon device 105 during a typical neighboring base station discovery procedure. ) May be sent to prevent the base station from attempting a handoff by mistaken).

The small mobile communication base station beacon device 105 may be implemented as a single device integrated with the wireless LAN AP 103 or may be implemented as a separate device from the wireless LAN AP 103. It is installed in the same position as the WLAN AP (103).

Meanwhile, the neighbor base station list information of the mobile communication base station 101 is included in the small base station beacon for the WLAN AP search so that the terminal can quickly detect the small mobile communication base station beacon device 105 in a typical neighbor base station search procedure. The specific cell identifier assigned to the device 105 is included.

As a method of searching for a WLAN AP using the small mobile communication base station beacon device 105 according to the present invention, there is a method of independently performing a terminal and a method of notifying the terminal after detection in a mobile communication network.

2 is a flowchart illustrating a case where a terminal independently discovers a WLAN AP. In the drawing, reference numeral s201 denotes a typical mobile communication neighbor cell search procedure of the terminal. The terminal detects the specific cell identifier transmitted by the small mobile base station beacon apparatus through this procedure. When the specific cell identifier allocated for WLAN AP discovery is detected (s202), the WLAN AP discovery and WLAN access procedure is performed (s203).

In this case, if the strength of the signal corresponding to the specific cell identifier is greater than or equal to the threshold, the terminal may determine that there is a WLAN AP available nearby, and perform the WLAN AP discovery and WLAN access procedure (S203).

Subsequently, if the WLAN connection is successfully established (S204), the terminal performs a vertical handoff from the mobile communication network to the WLAN (S205).

On the other hand, during a typical mobile communication neighbor cell search procedure (s201), the terminal reports the cell identifier and signal strength of the neighbor cell that satisfies a specific condition to the mobile communication base station, and the base station determines whether to handoff between base stations based on this. Since the small mobile communication base station beacon device corresponding to the specific cell identifier has only a beacon channel, not a normal mobile communication base station capable of processing traffic, a method of preventing handoff to the small mobile communication base station beacon device This is necessary.

Therefore, the present invention provides the following three methods as a solution to this.

First, in the terminal call processing software, the cell identifier and signal strength of the small mobile communication base station beacon device may be ignored without being transmitted to the mobile communication base station.

Second, the signal strength of the small mobile base station beacon in the mobile base station call processing software can be ignored.

Third, the small mobile base station beacon apparatus may transmit control information for preventing vertical handoff to itself. For example, in the case of a small mobile communication base station beacon device for UMTS, a handoff attempt may be prevented to itself through a normal cell indicator (NCI) through a PCCCH.

3 is a flowchart illustrating a method of notifying a terminal by determining whether a vertical handoff is performed from a mobile communication network to a WLAN AP. Typically, the terminal 107 reports the neighbor base station discovery information including the cell identifier of the neighbor cell satisfying the condition during the mobile communication neighbor cell search procedure and the corresponding signal strength information to the mobile communication base station 101, and the mobile communication base station 101. 101 determines whether to handoff by analyzing this (S301).

In the mobile communication network-based WLAN AP discovery method according to the present invention, when the terminal 107 exists within the coverage of the WLAN AP, the specific cell identifier allocated for the discovery of the WLAN AP in the neighbor base station discovery information reported by the terminal 107. Included.

The mobile communication base station 101 receives it from the terminal 107 and transmits it to the vertical handoff control server 301 (S302). The vertical handoff control server 301 reports the reported signal strength, user profile, and operator. It is determined whether the vertical handoff is performed to the WLAN AP based on the policy, and when it is determined that the vertical handoff needs to be performed, a handoff instruction message is sent to the terminal 107 (S303). When the terminal 107 receives this message from the vertical handoff control server 301, the terminal 107 performs a vertical handoff procedure to the WLAN AP.

In this case, when the signal strength corresponding to the specific cell identifier is greater than or equal to a predetermined threshold, the mobile communication base station 101 includes information on the specific cell identifier in the neighbor base station discovery information. Can be set to send.

4 is a view showing a small mobile communication base station beacon apparatus according to the present invention. The small mobile communication base station beacon apparatus 400 according to the present invention includes a controller 401, a digital signal processor 402, a beacon transmitter 403 including a D / A and frequency converter 406 and a power amplifier 407, and the like. It consists of.

In addition, the small mobile communication base station beacon device is applied to a mobile communication technology (e.g., synchronous CDMA, TDD technology, etc.) that requires synchronization between base stations in a typical mobile communication neighbor cell search procedure or mobile communication neighbor cell search performance. It may be configured to further include a synchronization receiver 405 if necessary to improve. The synchronization receiver 405 may be implemented by one of a GPS receiver, a mobile communication terminal receiving module, and an IEEE 1588 synchronous reception LAN interface.

Referring to the operation of the small mobile communication base station beacon apparatus according to the present invention configured as described above, the digital signal processor 402 generates a beacon channel digital signal data including a specific cell identifier assigned for the WLAN AP discovery beacon transmitter To the D / A and frequency converter 406 of 403. The D / A and frequency converter 406 converts the digital signal data from the digital signal processing unit 402 into an analog signal, converts it into a transmission frequency band, and transfers the signal to the power amplifier 407. The power amplifier 407 amplifies the transmission band analog signal from the D / A and frequency converter 406 to an appropriate output level and transmits it through the transmission antenna 404.

The controller 401 controls the operations of the digital signal processor 402 and the beacon transmitter 403 and provides timing and frequency references thereto.

The digital signal processing unit 402 of the small mobile communication base station beacon device 400 according to the present invention is generally implemented as an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), but a simple memory or shift register. It may be implemented in memory.

In this case, the beacon channel digital signal data generated through the digital signal processing in advance is stored in the memory or the shift register. In this case, the stored signal data is transferred to the D / A converter under the control of the controller 401.

On the other hand, since the synchronization receiver 405 has technical limitations for each implementation method, it is necessary to mix these methods appropriately.

First of all, when using a GPS receiver, the installation location of the small mobile communication base station beacon device is limited, and in some cases, a GPS antenna and an additional cable need to be installed. In particular, there is a disadvantage that the initial timing acquisition time is long in an in-building environment where the GPS signal is weak. Therefore, it is desirable to apply the GPS receiver to shaded areas such as islands or areas where mobile communication base station signals are weak and difficult to establish a wired infrastructure.

In case of utilizing the IEEE 1588 technology, a timing server must be provided in the wired IP network, and in particular, all routers and switch devices in the WAN section between the timing server and the small mobile base station beacon device must be upgraded to support IEEE 1588. . Therefore, it is desirable to apply the IEEE 1588 technology when the wired infrastructure supports IEEE 1588.

On the other hand, in the case of using a mobile communication terminal receiving module, there is a disadvantage that it is difficult to use in a mobile communication shadow area or a place where the signal is weak. Therefore, it is preferable to apply this method to an environment where mobile communication signals are well received, such as indoors, and where GPS or IEEE 1588 technology is difficult to apply.

On the other hand, the small mobile base station beacon apparatus according to the present invention may have a plurality of digital signal processing units (502-1 ~ 502-k) to support a plurality of mobile communication technologies, a plurality of FA (Frequency Assignment) or a plurality It may have a plurality of beacon transmitters (503-1 ~ 503-k) to support the number of bands. In this case, the digital signal data of the beacon channel generated by each digital signal processor is transferred to the plurality of beacon transmitters, converted into analog signals, converted into transmission frequency bands, and then amplified to an appropriate signal strength. Thereafter, they are combined via signal combiner 508 and then sent out via transmit antenna 504.

Claims

A method for discovering a WLAN AP for vertical handoff of a terminal from a mobile communication network to a wireless LAN,

A first mobile station base station beacon apparatus transmits a specific cell identifier previously allocated to the mobile station base station beacon apparatus through a beacon channel including some channels used in the wireless access technology of the mobile communication network; step;

A second step of detecting, by the terminal, the specific cell identifier through a normal neighbor cell search procedure of the mobile communication network;

A third step of preventing a terminal from handing off to the mobile communication base station beacon device based on the specific cell identifier in a typical neighbor cell search procedure of the mobile communication network; And

A fourth step in which the terminal discovers the WLAN AP through a WLAN AP discovery procedure and performs a vertical handoff with the WLAN AP.

WLAN AP discovery method for a vertical handoff from the mobile communication network to the WLAN.
The method according to claim 1,

The beacon channel is composed of a pilot channel only, a pilot channel and a synchronization channel or a pilot channel and a synchronization channel and a control channel, characterized in that the WLAN AP discovery method for a vertical handoff to a wireless LAN in a mobile communication network .
The method according to claim 1,

The specific cell identifier is a WLAN AP discovery method for vertical handoff from a mobile communication network to a wireless LAN, characterized in that the cell-ID transmitted through a PN offset or a synchronization channel.
The method according to claim 1,

The mobile communication base station beacon device is a WLAN AP discovery method for a vertical handoff from the mobile communication network to the wireless LAN, characterized in that implemented as a device independent of the WLAN AP.
The method according to claim 1,

The mobile communication base station beacon apparatus is implemented as an integrated device with a wireless LAN AP, the WLAN AP discovery method for the vertical handoff from the mobile communication network to the wireless LAN, characterized in that sharing the module with the wireless LAN AP.
The method according to claim 1,

The second step may further include determining that there are available WLAN APs in the vicinity when the signal strength corresponding to the specific cell identifier is greater than or equal to a threshold, for wireless handoff from the mobile communication network to the WLAN. How to discover LAN AP.
The method according to claim 1,

In the third step, the terminal recognizes the specific cell identifier and prevents the handoff from reporting the strength of the specific cell identifier or a signal corresponding thereto to the mobile communication base station. WLAN AP discovery method for vertical handoff to LAN.
The method according to claim 1,

In the third step, the mobile communication base station recognizes the specific cell identifier, thereby preventing the handoff by ignoring the specific cell identifier or signal strength corresponding thereto. WLAN AP discovery method for off.
The method according to claim 1,

In the first step, the mobile communication base station beacon apparatus transmits control information for preventing handoff through a control channel included in the beacon channel,

The third step is a WLAN AP discovery method for a vertical handoff from a mobile communication network to a wireless LAN, characterized in that the terminal does not attempt to handoff to the mobile communication base station beacon device based on the control information.
The method according to claim 1,

The second step is

Reporting, by the terminal, a specific cell identifier and a corresponding signal strength to a mobile communication base station through a mobile communication neighbor cell search procedure; And

The mobile communication base station further comprises the step of reporting to the vertical handoff control server when the signal strength is above a certain threshold,

The fourth step is

When the terminal receives a message for detecting the WLAN AP corresponding to the specific cell identifier from the vertical control server, the vertical handoff from the mobile communication network to the wireless LAN is performed. WLAN AP discovery method for.
A digital signal processor for generating a digital signal of a beacon channel including a specific cell identifier allocated for WLAN AP discovery;

A beacon transmitter that converts the digital signal of the digital signal processor into an analog signal, converts the signal into a transmission frequency, amplifies and transmits the signal to a coverage corresponding to the coverage of the corresponding WLAN AP through an antenna; And

And a controller for controlling the digital signal processor and the beacon transmitter and providing a timing and frequency reference signal.

The beacon transmitter is a small beacon base station beacon apparatus for a wireless LAN AP discovery for the vertical handoff from the mobile communication network to the wireless LAN, characterized in that the method for transmitting a beacon signal continuously or at a predetermined interval.
The method according to claim 11,

Further comprising a plurality of digital signal processing unit for supporting a plurality of different mobile communication technology,

Corresponding to each of the digital signal processing unit, the WLAN AP for the wireless handset for vertical handoff from the mobile communication network to the wireless LAN further comprising a plurality of beacon transmitters for supporting different frequency (FA) or frequency band (band) Small Mobile Base Station Beacon
The method according to claim 11,

When applied to a technology that requires network synchronization between base stations in order to search for neighboring base stations of a mobile communication, the mobile station further includes a synchronization receiver including one of a GPS receiving module, a base station forward channel receiving module, and an IEEE 1588 sync receiving module. Small mobile communication base station beacon device for WLAN AP discovery for vertical handoff to LAN.