KR101208130B1 - System and method for synchronizing radio service between celluar network and wlan network - Google Patents

Abstract

PURPOSE: A wireless service interworking system between a cellular network and a WLAN(wireless local area network) and method thereof are provided to offer system interworking by converting a part of radio resources in the WLAN. CONSTITUTION: When a terminal(120) connects to a WLAN through a WLAN communication modem, an FSC(frame switching control) unit(121) transmits frames generated in all transmission channels to an LCP(link control proxy)(122). The LCP terminates a message used between an interface and an RAN(radio access network) for setting the wireless link of cellular communication in the frames. The LCP transmits the other frames to an aggregator(420). The aggregator converts the transmitted frame into a frame matched with a cellular communication interface.

Description

System and method for synchronizing radio service between celluar network and WLAN network

The present invention relates to a wireless service interworking system and a method for interworking between a cellular network and a wireless LAN (WLAN) network, and more particularly, an existing cellular network and a WLAN network using Wi-Fi are the same. By using the WLAN as a part of the cellular network by interworking with the network, providing a continuous wireless service between the cellular network and the WLAN, when the user terminal needs to move the wireless service from the cellular network to the WLAN network, the load of the base station By seamlessly transitioning to the WLAN network, the cellular service and the WLAN network wireless service to reduce the burden on the base station without inconvenient the user, and at the same time ensure the maximum speed of the user's wireless service in the amount equivalent to that provided by the WLAN. It relates to a linkage system and a linkage method.

The present invention also relates to a wireless service interworking system and a method for interworking between a cellular network and a WLAN network in which cellular networks and WLAN networks using limited radio resources can be used as one network.

1 shows the structure of a system operating in a conventional cellular network. User Equipment (UE) 110 is connected to a Radio Access Network (RAN) 210, and the RAN 210 is connected to a core network including a MSC / GSN 310. That is, the RAN 210 is responsible for the connection between the UE 110 and the core network. In this case, the RAN 210 performs a radio resource allocation procedure to form a radio link with the UE 110. The cellular network consists of a control plane (signaling interface) and a user plane (traffic interface).

Based on this, we will look at the main Components.

Radio access network (RAN) 210 (or base station subsystem) (BSS) controls radio access and connection with UE 110, and also controls a radio link. The device is connected to the MSC / GSN (310).

The RAN 210 is composed of one Radio Network Controller (RNC) and several Node-Bs.

At this time, the Node-B has a radio transmission reception component and forms one cell.

A radio network controller (RNC) controls resource allocation and control for radio access and access to a core network.

In addition, the RNC controls radio access and connection with the UE 110 through Node-B control.

The non-access stratum (NAS) of the UE 110 is located at the best part of the protocol interface between the UE 110 and the core network, so that the last operation of the entire network service establish procedure is performed. That's what happens.

 This part is responsible for call service and data service session setup. This layer consists of the SM / CC / MM / GMM / SMS protocol interfaces, and when communication between the UE 110 and the core network occurs, the RAN 210 system is a bridge for communication ( bridge). Below are the main features of this section.

First, voice communication is controlled through logical state machine control, and the user's voice traffic is controlled according to the state of the logical state.

Second, it controls data communication through logical state machine control by data communication, and activates or deactivates communication status of data. In this procedure, the UE 110 performs MSC / GSN ( In step 310, an IP is allocated from a GSN.

Third, when the UE 110 moves to a new cell through mobility management, the UE 110 is involved in registration with a new cell, and takes charge of handover occurring during an idle mode.

Meanwhile, Radio Resource Control (RRC) of the UE 110 corresponds to a brain in a radio system of a cellular network, and radio resource control for a radio link between the UE 110 and the RAN 210. The main functions are as follows.

First, in order to establish a radio connection between the UE 110 and the RAN 210 in a cellular network through radio resource management, the UE 110 and the RAN 210 allocate radio resources, respectively. In the process of allocating radio resources, the UE 110 and the RAN 210 exchange their allocated radio resource parameters through a radio protocol interface. At this time, the RRC protocol interface carries the information.

Second, when the UE 110 activates a session through connection and mobility management, it performs a function of allocating and releasing connections with each cell when roaming a cell. The RRC constantly monitors a radio cell to which the UE 110 belongs and a radio cell adjacent to the neighbor, thereby monitoring and performing a condition for performing a handover by confirming a state of a radio link.

Third, as a connection state, the RRC layer monitors the state of the RAN 210 and performs functions such as mobility management.

Radio resource control (RLC) of the UE 110 performs a radio link operation between the UE 110 and the RAN 210. It is located between the upper level information such as RRC, PDCP, BMC and logical channels, and acts as a bridge. This layer is involved in frame transmission between the UE 110 and the RAN 210.

When transmitting a frame between the UE 110 and the RAN 210, transmission and reception are performed according to a predetermined packet size to be transmitted, thereby maximizing efficiency by utilizing a limited cellular radio bandwidth. The main features of RLC are:

Firstly, with segmentation / re-assembly of data, when a large amount of data is transmitted, the large data is separated into smaller sizes, transmitted and then re-assembled on the other side. At this time, the RLC assigns a sequence number to each partitioned data so that it is used at the time of combining at the destination.

Second, due to error detection and recovery, the radio link between the UE 110 and the RAN 210 is very unstable in nature. Therefore, the main task of the RLC is to detect transmission errors due to this unstable state and to perform a recovery mechanism.

Third, RLC operates in three modes to increase efficiency in AM / UM / TM mode. AM (Acknowledged Mode), TM (Transparent Mode), and UM (Unacknowledged Mode).

Since the radio link of the UE 110 and the RAN 210 has an inherently unstable element, packets transmitted between the UE 110 and the RAN 210 may be damaged or lost. Thus, signaling and traffic compensate for some degree of such packet corruption or loss through appropriate modes. For example, in the AM mode, it is used for reliable transmission. In this case, an ARQ protocol (Automatic Request for retransmission) is used to correct wrongly received data.

Also, when it is more important to send urgently than correcting damaged or lost data, the transmission itself can be prioritized using the TM or UM mode.

Fourth, if security is required as the ciphering of control data, after establishing ciphering through negotiation between the UE 110 and the RAN 210. This ciphering may be applied to all packets transmitted in the RLC to provide security between the UE 110 and the RAN 210.

Meanwhile, the media access control (MAC) of the UE 110 maps a logical channel of an upper end to a transport channel of a lower end. In this case, the transport channel is connected to a physical channel. The MAC is responsible for the inner loop and outer loop radio quality control. Detailed functions are as follows.

First, as a multiplexing of logical channel data, the MAC layer is responsible for a hybrid ARQ function. In this case, automatic retransmission of a corresponding transport block is performed. In addition, MAC performs logical multiplexing with upper and lower ends by mapping logical channels to transport channels.

Second, Priority handling of the data flows, one of the essential functions for maximizing limited radio resources, this feature prioritizes and lowers each session in the MAC. By classifying the priority, and by using dynamic scheduling, each packet to be transmitted is determined by prioritization, so that the limited radio bandwidth can be utilized to the maximum.

Third, by calculating the size of the data to be transmitted by traffic volume monitoring, select one of several predefined transmission size formats, and select a frame of a size that best fits the frame. It prevents unnecessary waste of frames.

Fourth, if security is required through ciphering of voice data, the MAC layer may perform ciphering for traffic through negotiation between the UE 110 and the RAN 210. have.

FIG. 2 is a diagram illustrating a protocol interface in a system operating in a conventional cellular network. First, a control plane will be described with reference to FIGS. 1 and 2.

Node-B of UE 110 and RAN 210 each have a physical radio resource. The RRC / RLC / MAC protocol interface of the UE 110 operates between the UE 110 and the RAN 210. This layer establishes or breaks a radio link between the UE 110 and the RAN 210. The RLC and the MAC of the UE 110 are responsible for transmitting the RRC between the UE 110 and the RAN 210.

The RANAP (Radio Access Network Application Part) of the RAN 210 and the MSC / GSN 310 configures a transport interface between the RAN 210 and the core network, and the UE 210 and the core network signaling message ( It carries a signaling message). In addition, some RAN 210 performs access control through negotiation with the core network.

Non Access Stratum (NAS) of the MSC / GSN 310 operates between the UE 210 and the core network, and the RAN 210 is responsible for relaying. This protocol interface controls a CS (Circuit Switched) domain, that is, a voice communication service, and a PS (Packet Switched) domain, that is, a data communication service. This interface manages the logical state for a user session.

Meanwhile, when a user starts an application session, the UE 110 starts communication with the RAN 210 through the RRC layer and requests a radio resource allocation procedure, where the RRC / RLC / Communicate with RAN via MAC. Thereafter, when the UE 110 receives authentication from the core network through the RAN 210, the RAN 210 allocates radio resources for a radio link between the UE 110 and the RAN 210. In this case, parameters for transmitting traffic between the corresponding RLC and MAC layer also between the UE 110 and the RAN 210 are set up.

Meanwhile, we will look at the user plane.

Circuit switched domains are generally involved in voice service traffic. Voice frames operate at 20 ms intervals, so 50 frames per second are transmitted through the RLC / MAC layer. The RLC / MAC layer can flexibly select a transmission option upon frame forwarding, and this configuration is formed via RRC in the initial radio resource allocation stage. The voice frame is delivered from the UE 110 to the RAN 210 via the RLC / MAC layer, and the RAN 210 passes back to the core network through a Frame Protocol (FP) interface.

Packet Switched (PS) domains are involved in data services. Packets can operate at regular intervals or in burst mode, and the transmission size can be dynamically adjusted in each mode. During transmission, the RLC / MAC can choose the transmission size to suit each mode and payload size, and these options are configured on the radio resource allocation stage. A user packet, that is, an IP packet, is transmitted from the UE 110 to the RAN 210 via RLC / MAC through a Packet Data Convergence Protocol (PDCP) interface, and the RAN 210 converts the PDCP into a GTP to be delivered to the core network. do.

3 is a diagram illustrating a conventional signal flow based on FIGS. 1 and 2, and illustrates a case of a mobile originating voice call in a terminal.

First, an RRC-Connection Request is performed (S1). More specifically, when a user starts a call service, a connection request is sent to the RNC through a common radio link established with Node-B to allocate UE radio resources.

NBAP-Radio Link Setup is performed (S2). More specifically, after the RNC allocates a traffic channel radio resource (S2, S3), the RNC issues a command to allocate a physical radio resource to the Node-B (S4). Afterwards, Node-B and RNC prepare traffic processing of the newly allocated channel through a lower layer sync process (S5).

After step S5, RRC-Connection Setup is performed (S6). More specifically, after the radio resource is allocated, the RNC sends radio resource allocation information to the UE 110 via Node-B.

After step S6, NABA-Radio Link Restore Indication is performed (S7). After the UE 110 receives radio resource information from the RNC, when the UE 110 tunes in to Node-B using the information, the Node-B searches for this and then informs the RRC of this fact. Report.

After step S7, RRC-Connection Setup Complete is performed (S8). The UE 110 establishes a radio link with the Node-B using the received radio resource, and then sends this progress to the RNC.

After step S8, RRC-Measurement Control is performed (S9). After establishing a Node-B radio link with the UE 110 and receiving an RRC-Connection Setup Complete, the RNC issues this message to the UE 110 to allow the UE 110 to monitor the surrounding radio situation and report it to the RNC. do.

After step S9, Initial Direct Transfer-CM Service Request is performed (S10). After the UE 110 establishes a radio link for the traffic channel with the Node-B of the RAN 210, the UE 110 enters a NAS session establishment step for call service. At this time, the UE 110 first sends a message to the RAN 210 and the necessary information is extracted and delivered to the core network.

Then, after receiving a message from the UE 110, the MSC (Mobile Switching Center) of the MSC / GSN (310) after the authentication and encryption process with the UE (110), and sends a response to the UE (110) Give (S11 to S13).

DT-CC Setup is performed (S14). When UE 110 requests the MSC of MSC / GNS 310 to set up a call service, the MSC allocates one voice circuit from the digital trunk for that call.

After step S14, DT-Radio Bearer Assignment is performed (S15).

After allocating the voice circuit, the MSC notifies the RNC of the fact and informs the bearer channel information for voice established in the RNC and MAC.

After step S15, the same steps S16 to S20 as steps S1 to S7 are performed, followed by RRC-Radio Bearer Setup (S21 and S22).

More specifically, the RNC informs Node-B through "NBAP-Radio Link Reconfigure Preparation" that the type of traffic channel is in voice mode and then informs the UE 110 of such content.

Accordingly, in the case of voice communication, when the call counterpart receives a call, the MSC sends “DT-CC Connect” to the UE 110, and the voice communication session establishment is completed (S23 and S24).

On the other hand, the current cellular wireless communication network in this process is a traffic congestion due to the increased use of video streaming.

As a result, serious quality degradation is occurring in the overall cellular network wireless service such as out of voice communication and slowing down of data communication.

However, as the existing limited cellular radio frequency band, the technical limit is reached to fully support the rapidly increasing wireless traffic.

Cellular wireless communication networks are also very difficult to control. Therefore, a very complex software and hardware are required to configure a cellular wireless network, which inevitably increases the cost of the equipment, which requires a high initial introduction cost and a high maintenance cost when configuring the wireless network. The cost of the quality of the wireless service is very high and the cost of the wireless network configuration is very high.

In addition, it is impossible to support the explosive increase in user traffic by simply expanding the wireless infrastructure.

Therefore, the following method was attempted to solve this problem.

Firstly, it is a femtocell, which is a mini base station having a wireless coverage of about 30 meters. Advantageously, this equipment is the same technology as the large base stations that make up large cellular networks. Therefore, since a large base station and a network interface are the same, service interworking with the existing large network system is seamless.

Disadvantages include high cost and use of the same frequency as large cellular networks, resulting in radio interference with large base stations. In addition, since the base station management must be precisely performed, the system management is complicated, and when the installation is difficult, problems may occur in operation, which is not easy for general users to install.

Secondly, Unlicensed Mobile Access (UMA), which is advantageous because it uses a WLAN using Wi-Fi, so no base station is required. In addition, because it uses unlicensed frequencies and users install WLANs, operators do not need to install a network at all, and use a myriad of existing WLANs. Network service is available.

On the downside, this standard is not an interface to support cellular networks, so there is no sophisticated control technology supported by cellular networks. Therefore, when the network state is unstable, the environment is not sufficiently controlled, causing a problem of stability in the terminal. In particular, the UMA is a standard different from the cellular network. Since the UMA constitutes an independent network completely different from the cellular network, it is necessary to implement a separate interface between the terminal and the server. In particular, since the protocol conversion engine must be created separately for interworking with the cellular network on the server side, the maintenance of the terminal and server is complicated and expensive, and each time a new version of the specification is released, the UMA and the cellular interface There is a constant management factor for coherence.

Accordingly, new technology development is required to overcome the disadvantages of these conventional technologies.

[Related Technical Literature]

1. Method and system for coordinating services in an integrated WLAN-cellular system (Patent Application No. 10-2005-7018525)

The present invention is to solve the above problems, by using the WLAN as a part of the cellular network by interworking the existing cellular network and the WLAN network using Wi-Fi as the same one, cellular network and WLAN In order to provide continuous wireless service between users, and when the user's mobile needs to move the wireless service from the cellular network to the WLAN network, the load of the base station is seamlessly transferred to the WLAN network, without burdening the user without causing inconvenience to the user. The present invention provides a wireless service interworking system and a method of interworking with a cellular network and a WLAN network for maximally guaranteeing the maximum amount of wireless service speed of a user as provided by a WLAN.

However, the objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In a wireless service interworking system of a cellular network and a WLAN network according to an embodiment of the present invention, when a terminal including a WLAN communication modem and a cellular communication modem is connected to a WLAN through the WLAN communication modem, Frame Switching Control (FSC) for transmitting frames generated in all transport channels of the UE to a Link Control Proxy (LCP) and Radio Access Network (RAN) for wireless link setup of cellular communication among frames received from the FSC Terminating the message used for the interface with the terminal, and converts the frame transmitted from the terminal and the terminal including the LCP to the frame matching the cellular communication interface to pass the remaining frame to the aggregator (aggregator) core network It includes the aggregator to transmit to.
In addition, the wireless service interworking method of a cellular network and a WLAN network according to an embodiment of the present invention when a terminal including a WLAN communication modem and a cellular communication modem is connected to the WLAN through the WLAN communication modem As the user starts the application, when the terminal transmits an RRC (Radio Resource Control) Connection Request message to the network, the frame switching control (FSC) included in the terminal includes the RRC Connection Request message in the terminal. A first step of routing to a Virtual Transport Channel (VTC) of a Link Control Proxy (LCP); A second step of the LCP, transmitting an RRC Connection Setup message to the terminal through RRC together with a predefined RRC parameter; A third step of the LCP, via the FSC, when the UE sends an RRC Connection Complete message; And a fourth step of controlling the LCP to transmit an RRC Measurement Control to the terminal so that the terminal sends a periodic report on a link state to operate according to a cellular communication standard.

The wireless service interworking system and interworking method of the cellular network and the WLAN network according to an embodiment of the present invention can be applied directly to 3G as well as 4G by solving the essential part of the interface problem existing between the cellular network and the WLAN network. Provide effect.

In addition, the wireless service interworking system and interworking method of a cellular network and a WLAN network according to another embodiment of the present invention, when the terminal moves to the WLAN area, while the terminal operating in the cellular network continuously operating in the same cellular interface, By replacing only the radio resource portion of the WLAN, the user can provide interoperability of the system without disconnection of the network.

In addition, in case of real-time streaming such as IMS, it provides seamless operation between cellular network and WLAN network, and improves wireless speed when moving in WLAN network to provide high quality real time video services. Can be.

In addition, the wireless service interworking system and the interworking method of the cellular network and the WLAN network according to another embodiment of the present invention, by connecting the Wi-Fi already installed in each building, furniture throughout the country to the cellular network very few operators As an initial cost, it is possible to expand the cellular network indefinitely, and when the user establishes Wi-Fi, the operator can also continuously expand the network without additional cost and contribute to eliminating the region.

In addition, the wireless service interworking system and interworking method of a cellular network and a WLAN network according to another embodiment of the present invention, since the service interworking between the cellular network and the WLAN network is seamlessly connected to the method aspect of reducing the burden on the base station in an overloaded state Provides the expected effect.

In addition, the wireless service interworking system and the interworking method between the cellular network and the WLAN network according to another embodiment of the present invention, by attracting the user's traffic into the operator's network, without the addition of a base station, a better opportunity to create a new service To provide an effect.

1 is a diagram illustrating a structure of a system operating in a conventional cellular network.
2 is a diagram for explaining a protocol interface in a system operating in a conventional cellular network.
3 is a diagram illustrating a conventional signal flow based on FIG. 1 and FIG. 2, illustrating a case where a voice call occurs in a terminal.
4 is a diagram illustrating a wireless service interworking system between a cellular network and a WLAN network according to an embodiment of the present invention.
5 is a diagram illustrating a control plane protocol interface in the architecture of a wireless service interworking system between a cellular network and a WLAN network according to an embodiment of the present invention.
FIG. 6 is a diagram illustrating a user plane protocol interface in an architecture of a wireless service interworking system between a cellular network and a WLAN network according to an embodiment of the present invention. FIG.
FIG. 7 illustrates system components and operations in an architecture of a wireless service interworking system between a cellular network and a WLAN network according to an embodiment of the present invention. FIG.
8 is a flowchart illustrating a case in which a voice call is generated through a WLAN in a method for interworking a wireless service between a cellular network and a WLAN network according to an embodiment of the present invention.

Hereinafter, a detailed description of a preferred embodiment of the present invention will be described with reference to the accompanying drawings. In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

In the present specification, when any one element 'transmits' data or signals to another element, the element can transmit the data or signal directly to the other element, and through at least one other element Data or signal can be transmitted to another component.

4 is a diagram illustrating a wireless service interworking system between a cellular network and a WLAN network according to an embodiment of the present invention.

The wireless service interworking system of the cellular network and the WLAN network according to the present invention is a technology that allows the UE 120 to operate with a cellular interface over Wi-Fi. Accordingly, the UE 120 provides a method of switching only the physical layer between the two networks so that service is not interrupted while viewing the state of the cellular or WLAN network, so that the lower layer is a cellular network or While using the Wi-Fi modem 123 using the WLAN network, the upper stage is a technology that unifies the service interworking and simplify maintenance by unifying the method using the cellular modem 122 which is a cellular network interface. . This technology is flexible for 3G as well as 4G.

More specifically, when Wi-Fi (or unlicensed wireless radio) starts to operate under a certain condition, the UE 120 operating on the cellular modem 122 uses the Wi-Fi modem 123 to establish a WLAN connection. It will work.

At this time, the aggregator 420 collects the interfaces operating on the WLAN and directs them to the core network. In the terminal, since the state information of all the cellular interfaces of the upper end operated at this time is continuously connected with the core network, the terminal can provide a seamless service in the cellular network and the WLAN network.

The aggregator 420 uses a standard cellular interface when interworking with the core network, and only serves to bring all the terminals connected to the WLAN into one, so that the technical complexity is low, so development is easy, and maintenance costs are very high. low.

5 is a diagram illustrating a control plane protocol interface in the architecture of a wireless service interworking system between a cellular network and a WLAN network according to an embodiment of the present invention, and FIG. 6 is a cellular network according to an embodiment of the present invention. A diagram showing a user plane protocol interface in the architecture of a wireless service interworking system in a WLAN network.

4 to 6, the UE 120, which is the terminal side, is composed of two components, and the network includes an aggregator 420 that serves as an aggregator 420. It is composed. In the UE 120, there are a Frame Switching Control (FSC) 121 and a Link Control Proxy (LCP) 122. Here, the FSC 121 determines whether the upper frame goes to the cellular module or the Wi-Fi module, and the LCP 122 terminates the pure air interface portion of the RRC / RLC / MAC started from the UE 120. Terminate function.

Here, the NAS portion of the UE 120 goes to the aggregator 420 via the WLAN 410. The aggregator 420 collects information from each terminal into a single channel to fit the interface to the core network. It uses the standard RANAP protocol as it is.

Meanwhile, the protocol interface description based on FIGS. 5 and 6 will be described.

In the network system proposed in the present invention, the LCP 122 in the UE 120 is connected to the aggregator 420 via the WLAN 410, and the LCP 122 and the aggregator 420 are STUN. Tunneling technique is used.

If security is needed, a VPN can be added here. The aggregator 420 is then connected via a standard cellular interface with the MSC / GSN 320.

First, a signaling protocol interface is described. In the proposed system, the cellular network protocol interface operates in the WLAN 410 through Wi-Fi.

In the proposed system, the radio protocol of RRC / RLC / MAC interfacing with the RAN terminates in the LCP 122 inside the UE 120. Therefore, all messages of RRC / RLC / MAC are terminated inside the UE 120 and do not go out to the network.

In the proposed system, NAS layer messages are delivered by the Link Control Proxy (LCP 122) via the aggregator 420 to the core network, where they are transmitted over a reliable channel. . Here, the aggregator 420 communicates with the core network via the RANAP interface.

Next, a look at the traffic protocol interface (Traffic protocol interface).

In the proposed system, the voice frame of the Circuit Switched (CS) domain is delivered by the LCP 122 in the UE 120 to the Real Time Transport Protocol (RTP) to reach the aggregator 420, which in turn The aggregator 420 converts the frame network (FP), which is a core network interface, to the MSC of the MSC / GSN 320.

In the proposed system, PDCP-IP packets of the PS (Packet Switched) domain are encapsulated.

It is delivered in the form of RTP through the LCP 122, reaches the aggregator 420, the aggregator 420 is converted to GTP and delivered to the GSN of the MSC / GSN (320).

FIG. 7 is a diagram illustrating system components and operations in an architecture of a wireless service interworking system between a cellular network and a WLAN network according to an embodiment of the present invention. 4 to 7, a component description of a UE 120 will be described first.

In the proposed system, the UE 120 is configured with a frame switching control (FSC) 121 and a link control proxy (LCP) 122.

The FSC 121 monitors the WLAN link status and determines whether to switch the upper transport channel frame according to the status. At this time, the transport channel to be processed is DSCH / SCH / BCH / PCH / FACH / RACH / MCH.

LCP 122 terminates the radio link control interface. Thus, the RRC / RLC / MAC ends inside the UE 120, and the NAS and user traffic are relayed to the aggregator 420.

Looking at the FSC 121 in more detail, the FSC 121 is located between the transport layer and the physical layer, and controls the flow of transport channels such as DCH / DSCH / BCH / PCH / MCH / RACH / FACH and performs processing. In charge.

When the UE 120 operates with the RAN through the cellular network, the FSC 121 maps the transmission channel to the cellular modem. When the UE 120 operates with the WLAN 410 network, all transmissions are performed. The frame generated in the channel is changed to a routing to the VTC (Virtual Transport Channel) 122d in the LCP 122 to allow the LCP 122 to process the frame.

Looking at the LCP 122 in more detail, first, the main task of the RRC interface performs a process for radio link setup, and the RLC / MAC performs a radio link mission under a cellular radio environment between the UE 120 and the RAN.

However, when the UE 120 operates in the WLAN 410 network, such an interface function is not necessary, so the LCP 122 terminates the RRC / RLC / MACs, which are cellular radio interfaces, and the radio initiated by the UE 120 is terminated. Termination processing is performed with appropriate predefined configuration parameters so that the operation of the interface does not become a problem.

LCP 122 also allows the cellular protocol interface of the upper end NAS to be well communicated to the core network. When performing this operation, a channel of a lower layer started from the UE 120 is connected to the LCP 122 through the VTC 122d to operate. Thus, the LCP 122 is connected to the core network through the aggregator 420.

The LCP 122 may operate even if the UE 120 has a private IP using a tunneling mechanism or a method of STUN to communicate with the aggregator 420.

It also has a VPN between the UE 120 and the aggregator 420 for a security mechanism.

LCP 122 monitors the Wi-Fi status and monitors the IP packet status to check the QoS status. Thus, as a result derived there, a decision is made to perform a handover between the WLAN and the cellular network.

The sub module of the L-RRC 122a serves to terminate the RRC protocol interface initiated at the UE 120. The upper layer protocol in the CS domain, namely NAS (CC / MM / SM / GMM), is delivered to the core network through this module.

In addition, the information of the NAS is transmitted between the UE 120 and the core network through this module. When the UE 120 is in the radio resource allocation phase, the module will respond to the UE 120 with predetermined parameters.

The L-RLC 122b terminates the RLC layer of the UE 120 and is also involved in terminating user traffic. In a voice service, when a voice frame is sent from the UE 120, the voice frame is converted into an RTP and sent to the aggregator 420. In the data service, when a PDCP including an IP packet is sent from the UE 120, the PDCP is terminated and then converted into an RTP and sent to the aggregator 420.

The L-RLC 122b also consists of simple predetermined parameter values at the time of initial radio link establishment, to concisely perform the operation of the RLC.

The L-MAC 122c is symmetrical to the MAC layer of the UE 120 and terminates the MAC interface occurring at the UE 120. L-MAC 122c adjusts the size of the frame to transmit and interacts directly with VTC 122d. The L-MAC 122c module is composed of simple predetermined parameter values to simplify the operation of the MAC.

VTC 122d is an emulation of a transport channel for Wi-Fi. The UE 120 establishes a radio link over the WLAN 410 and the VTC 122d replaces the physical channel function in place of the cellular modem, thereby allowing the UE 120 to correlate with the cellular or WLAN 410 network. It supports to operate transparently without

Thus, the UE 120 operates regardless of the physical layer or the type of the network. In this case, the VTC 122d serves as a bridge for connecting the upper interface with the core network through the aggregator 420.

The transport channel emulator supported by the VTC 122d is as follows.

FACH and RACH for signaling frame, DSCH and DCH for traffic channel frame, BCH for broadcasting, PCH for paging, and multicasting It is MCH.

Meanwhile, components of the aggregator 420 will be described.

The transport layer and physical layer of the aggregator 420 interwork with the core network through a cellular standard interface.

The aggregator 420 acts as an aggregator 420 that collects multiple terminals and expresses them as a single RNC for the core network, and there are some simplified parts existing between the UE 120 and the aggregator 420. It also performs the simple format conversion of private interfaces to standard interfaces.

The aggregator 420 has a RANAP on the SS7 to interwork with the core network, and carries NAS signaling to the core network.

In the CS domain, the aggregator 420 supports a Frame Protocol (FP) interface and interworks with the core network.

In the PS domain, the aggregator 420 supports a GPRS Tunneling Packet (GTP) interface and interworks with the core network.

The aggregator 420 supports tunneling so that the terminal can communicate with each other even when the terminal operates on a private IP.

The aggregator 420 has a QoS feedback function, which feeds back the state of traffic for the established session to the terminal, thereby enabling the terminal to perform quality management on the link state.

Meanwhile, an operation description of the UE 120 will be described.

First, let's look at WLAN mode.

When the Wi-Fi is operated in the UE 120, the Wi-Fi module establishes a radio link through a Wi-Fi access point (AP) and a physical layer through its own process and is assigned an IP. Thereafter, the UE 120 connects to the WLAN 410, where the LCP 122 module of the UE starts communication with the aggregator 420 through a tunneling mechanism.

The FSC 121 maps a transmission channel to communicate with a cellular physical modem in a cellular mode in which Wi-Fi does not operate.

When the UE 120 connects to the WLAN via Wi-Fi operation, the LCP 122 notifies the FSC 121 of such a change in link state, and then the FSC 121 hooks all transport channel operations. To route the frame to VTC 122d.

The VTC 122d of the LCP 122 will be described.

When the UE 120 operates on the WLAN 410, the frames of all transport channels are routed by the FSC 121 to the VTC 122d. All frames reaching the VTC 122d are raised to the L-MAC 122c via call back. The functions provided by the VTC 122d are as follows:

First, BCH represents information such as system ID, cell ID, neighbor cell information, etc., and is previously defined for WLAN without receiving information from the base station.

Secondly, the PCH will operate this channel when a request for call service comes down from the core network through the aggregator 420. At this time, the radio information is filled with radio values predefined for the WLAN 410, and then transmitted through the FSC 121 to the MAC layer of the UE 120.

Third, when multicast information reaches the LCP 122 via the aggregator 420 in the core network with the MCH, the value is represented by the MCH channel of the VTC 122d.

Fourth, the FSC 121 transmits the MAC layer.

Fifth, all signaling and user data sent from UE 120 by DCH / DSCH is processed over this channel in VTC 122d.

Sixth, the channel used before the UE 120 and the network first establish a connection with FACH / RACH, when the RACH frame originated in the UE 120 reaches the VTC 122d, the L-MAC of the LCP 122 The layer 122c / L-RLC / L-RRC 122a processes this and performs it to reach the core network via the aggregator 420. In the opposite direction, FACH is used.

Seventh, in the cellular interface, the MAC layer monitors frame quality and signal quality coming from the physical layer to perform power control. Thus, when the UE 120 operates on the WLAN 410, the VTC 122d generates such information in a transport and raises it to the MAC layer.

Next, the L-RRC 122a of the LCP 122 will be described.

When the user starts a voice or data service, the UE 120 requests the RAN for initial radio resource allocation using the RRC protocol, where the first requesting RRC message reaches the RAN through the RLC / MAC. In this case, when the UE 120 operates in the WLAN 410, a signaling frame is sent to the VTC 122d in the LCP 122, and the VTC 122d transmits the L-MAC 122c and the L-RLC 12b. The L-RRC 122a processes the corresponding message.

Unlike the cellular network, when the UE 120 operates in the WLAN 410, the cellular radio resource allocation between the UE 120 and the RAN is not necessary, and thus the LCP 122 omits a complicated radio resource allocation process. In connection with resource allocation, preset parameter values are sent to the RRC of the UE 120. Thus, the UE 120 recognizes that the radio resource is allocated based on the information sent from the L-RRC 122a of the LCP 122. This process simplifies the RRC procedure.

After the RRC process is finished, the UE 120 undergoes a core network and NAS signaling process, where the LCP 122 and the aggregator 420 only serve to relay the value through a reliable channel.

The L-RLC 122b of the LCP 122 will be described.

The RLC protocol of the cellular network performs a function of controlling an unstable radio link between the UE 120 and the RAN. The L-RLC 122b of the LCP 122 directly corresponds to the RLC of the UE 120. In this case, the L-RLC 122b is responsible for processing voice traffic, data traffic, and RRC generated in the UE 120. Since the L-RLC 122b interoperates directly with a memory copy in the same process as the RLC of the UE 120, the function of controlling the radio link, that is, complicated functions such as retransmission, sequencing, error recovery, etc. are eliminated. Implementation is simplified.

In addition, the operation of the L-RLC 122b is omitted because the implementation of frame segmentation, error detection and recovery, ciphering for control data, implementation of AM (transparent mode), TM (Unacknowledged Mode) operation mode, and the like are omitted. The implementation of the L-RLC 122b is simplified.

The L-MAC 122c of the LCP 122 will be described.

L-MAC 122c is implemented to correspond to the MAC layer of the cellular protocol interface. The MAC operates on a radio link between the UE 120 and the RAN, which provides functions such as prioritizing data flow, monitoring traffic volume and setting PDU sizes, and ciphering for voice data.

As the L-MAC 122c directly interfaces with the MAC in the same system domain in the terminal, when the UE 120 operates on the WLAN 410, the L-MAC 122c is not used as the functions of the existing MAC described above are not used. ) Will simplify the implementation.

According to this structure, let's take a look at Single TFC (Transport Format Combination).

When the voice service is started, voice traffic is sent to the RLC and MAC, which is reached by the FSC 121 to the VTC 122d. The L-RLC of the LCP 122 wraps the thus reached voice traffic with the RTP and transmits it to the aggregator 420. The aggregator 420 extracts the voice frame and delivers it to the MSC through the FP. .

In a typical cellular network, various types of transport format combination sets are determined in advance in order to use radio resources efficiently, and one of them is selected according to the size of data to be sent. However, in the WLAN mode, since the link between the RLC and the L-RLC 122b is a memory copy in the same process instead of the radio section, there is no limitation on bandwidth.

Therefore, the RLC and MAC layer uses one transport format (TF) to simplify the operation of the RLC and the MAC, and also simplify the complexity of the L-MAC 122c and the L-RLC 122b.

In the case of an operation for a data service, the UE 120 transmits a PDCP through an RLC, and the L-RLC 122b receives it and then sends it to the aggregator 420 in the form of RTP data.

The aggregator 420 converts it into a GTP form and retransmits it to the core network to perform a data service.

Next, we will look at QoS monitoring and Radio link Measurement.

When the UE 120 operates in WLAN mode, the LCP 122 monitors the link status of the Wi-Fi and monitors the QoS response coming from the aggregator 420 in real time. If the quality of the QoS coming from the link or aggregator 420 falls below a threshold, the LCP 122 informs the VTS of the current status and reports this value to the UE 120. At this time, according to the cellular protocol standard, the UE sends a measurement report message to the aggregator 420.

Next, let's look at tunneling.

When the UE 120 operates in WLAN mode, the UE 120 establishes a tunneling link for communication with the aggregator 420, and the aggregator 420 may be configured to have a private IP even if the UE 120 has a private IP. You will create a network that can communicate.

An operation description of the aggregator 420 will be described.

The core network is designed to communicate with some limited RNCs. Therefore, the aggregator 420 functions to bind all the UEs to be connected as one and make it appear as one RNC from the core network. At this time, the aggregator 420 gives session information to each of a plurality of UEs connected to each other and manages them, and at the same time, each UE is regarded as one traffic channel session for one access interface in the core network. Performs a multiplexing function.

When initially connected to WLAN 410, LCP 122 at UE 120 establishes a basic signaling channel by making a TCP / IP connection to aggregator 420.

Tunneling is then performed to establish a reliable, secure communication channel between the UE 120 and the aggregator 420.

After establishing a network connection between the UE 120 and the aggregator 420, they perform the functions defined in mutual cellular standards. Details are as follows.

UE 120 registration function, originating and receiving voice call processing, handover between cellular network and WLAN 410, data service activation / deactivation, SMS / multicasting, request for signaling from LCP 122 within UE 120 The aggregator 420 forwards this content to the core network. The cellular network interface with the MSC / GSN is RANAP.

When the voice traffic comes from the UE 120, the LCP 122 converts the data into the RTP form and then transfers the data to the aggregator 420, and the aggregator 420 converts it to the FP form and then delivers the same to the MSC. . The FP used at this time is the voice traffic interface between the RNC and the MSC.

When the data traffic comes from the UE 120, the LCP 122 converts the data into the RTP form, passes the data to the aggregator 420, and the aggregator 420 converts the data into the GTP form, and then delivers the data to the GSN. . The GTP used at this time is a data traffic interface between the RNC and the GSN.

The aggregator 420 collects QoS information for the packet when the service session is activated in the UE 120, and the aggregator 420 collects the collected information when the UE periodically polls the QoS state. Based on the feedback of the QoS to the UE (120).

When the UE 120 sends a measurement report, which is a standard cellular protocol interface, to the aggregator 420, the aggregator 420 posts a handover request message to the core network if necessary according to the information, and then the cellular network and the WLAN (410). Handover between) is performed.

8 is a flowchart illustrating a case where voice is generated from the UE 120 through a wireless LAN in a method for interworking a wireless service between a cellular network and a WLAN network according to an embodiment of the present invention. 4 through 8, the UE 120 operates in WLAN mode so that the FSC 121 routes the frame to the VTC 122d of the LCP 122 to the core network through the aggregator 420. This is an example of connecting.

As the user starts the application, the UE 120 first sends an “RRC Connection Request” message to the network (S51).

Since UE 120 is in WLAN mode, FSC 121 routes the signaling frame to VTC 122d of LCP 122.

LCP 122 terminates the “RRC Connection Request” message. In this case, the radio resource allocation process is omitted, and the LCP 122 transmits an “RRC Connection Setup” message to the UE 120 through the RRC with an appropriate predefined RRC parameter (S52).

After receiving the message, the UE 120 sends the message “RRC Connection Complete” through the FSC 121, the LCP 122 receives this message (S53).

Thereafter, the LCP 122 sends an “RRC Measurement Control” to allow the UE 120 to send a periodic report on the link state so that the LCP 122 operates according to the cellular standard (S54).

After the connection procedure is finished, the UE 120 moves to the NAS signaling stage. In this case, the UE 120 sends an “Initial Direct Transfer (DT) of CM: Setup” message to the network, and the LCP 122 transmits the message to the aggregator 420, and the aggregator 420 is SS7. Through the signaling trunk, a RANAP message is sent to the MSC of the MSC / GSN 320 (S55).

The MSC of the MSC / GSN 320 undergoes a UE identification process, using a message of “DT (Direct Transfer) MM: Authentication” (S56), and when a security setting is required, “DT MM: Security Mode”. Message follows (S57).

When the process for authentication and security between the MSC and the UE 120 of the MSC / GSN 320 is completed, the MSC of the MSC / GSN 320 sends a “DT CM: Service Accept” message to the UE 120. In step S58, connection to the core network is allowed.

When the UE 120 sends a “DT: Call Setup” to the MSC of the MSC / GSN 320 to proceed with the voice call setup process, a call setup message such as “DT: Call Proceed”, and “DT: Alert” is followed. Will follow (S59).

After allocating a channel in the voice trunk, the MSC of the MSC / GSN 320 sends a “Radio Bearer Assignment” to inform the aggregator 420 of the allocated voice channel information (S60). At this time, the aggregator 420 performs a trunk sync with the MSC based on the received information. In addition, the aggregator 420 informs that the channel set in the LCP 122 is a voice traffic type (S61).

The LCP 122 transmits “RRC: Radio Bearer Setup” to the UE 120 to inform that the voice channel of the UE 120 is set for voice (S62).

The UE 120 prepares to create a voice frame, and then sends a “RRC: Radio Bearer Setup Complete” message to the L-RRC 122a in the LCP 122 (S63), and the LCP 122 acknowledges this event. Notify the gregator 420 (S64), and the response of the "Radio Bearer Assignment" message to the MSC of the MSC / GSN 320 to the UE 120, aggregator 420 and MSC / Link establishment between the MSCs of the GSN 320 is completed (S65 and S66).

The present invention can also be embodied as computer-readable codes on a computer-readable recording medium. A computer-readable recording medium includes all kinds of recording apparatuses in which data that can be read by a computer system is stored.

Examples of the computer-readable recording medium include a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device and the like, and also implemented in the form of a carrier wave (for example, transmission over the Internet) .

The computer readable recording medium may also be distributed over a networked computer system so that computer readable code can be stored and executed in a distributed manner. And functional programs, codes, and code segments for implementing the present invention can be easily inferred by programmers skilled in the art to which the present invention pertains.

As described above, the specification and the drawings have been described with respect to the preferred embodiments of the present invention, although specific terms are used, it is only used in a general sense to easily explain the technical contents of the present invention and to help the understanding of the invention. It is not intended to limit the scope of the present invention. It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention can be carried out in addition to the embodiments disclosed herein.

120: UE 121: Cellular Network Protocol Interface
122: Cellular Modem 123: Wi-Fi Modem
220: RAN 320: MSC / GSN
410: WLAN 420: Aggregator

Claims (6)

When a terminal including a WLAN communication modem and a cellular communication modem accesses a wireless LAN through the WLAN communication modem, frames generated in all transport channels of the terminal are LCP (Link Control Proxy) Terminates the message used for the interface between the Frame Switching Control (FSC) to be transmitted to and the Radio Access network (RAN) for setting up a radio link of cellular communication among the frames received from the FSC, and the remaining frame aggregator ( the terminal including the LCP delivered to an aggregator; And
The aggregator converting the frame transmitted from the LCP into a frame matching the cellular communication interface and transmitting the frame to the core network
Wireless service interworking system of a cellular network and a WLAN network comprising a. The method of claim 1,
The LCP is
As a response message for a message used for interfacing with the RAN for setting up a radio link of cellular communication among frames received from the FSC, a predetermined response message is transmitted to the terminal to access the terminal. Control and, when the access procedure of the terminal is completed, delivers the remaining frame received from the FSC to the aggregator after the access procedure is completed. The method of claim 1,
The LCP is
The voice frame and the packet data frame among the frames received from the FSC are configured in the form of a real time transport protocol (RTP) to be delivered to the aggregator.
The aggregator
When the voice frame in the form of the RTP is delivered from the LCP, converts the voice frame to the FP (Frame Protocol) form and transfers it to the core network, when the packet data frame in the form of the RTP is delivered from the LCP And a wireless service interworking system of a cellular network and a WLAN network for converting the packet data frame into a GRS (GPRS Tunneling Packet) form and transferring the packet data frame to the core network. The method of claim 1,
The FSC is
When the terminal is not connected to the WLAN, a cellular network and WLAN for mapping the transmission channel of the terminal to the cellular communication modem to control the terminal to perform cellular-based communication through the cellular communication modem. Wireless service interworking system of network. When a terminal including a WLAN communication modem and a cellular communication modem accesses the WLAN through the WLAN communication modem, as the user starts the application, the terminal receives a Radio Resource Control (RRC) Connection Request message. Transmitting a RRC Connection Request message to a Link Control Proxy (LCP) included in the terminal when the SSC is transmitted to the network;
Transmitting, by the LCP, an RRC Connection Setup message together with a predefined RRC parameter to the terminal through RRC;
When the UE transmits an RRC Connection Complete message, the LCP receiving the RRC Connection Complete message through the FSC; And
Controlling the LCP to transmit a periodic report on a link status by transmitting an RRC Measurement Control message to the terminal;
Wireless service interworking method of a cellular network and a WLAN network comprising a. The method of claim 5, wherein
When the terminal sends an Initial DT (Direct Transfer) of CM: Setup message to the network, the FSC routes the Initial DT of CM: Setup message to the LCP, and the LCP sends the Initial DT of CM: Setup message. Transmitting a to an aggregator;
When the aggregator receives the Initial DT of CM: Setup message from the LCP, a radio access network application part (RANAP) message is transmitted through a signaling system 7 (SS7) signaling trunk, and a mobile switching center (MSC) of a core network. Transmitting to;
The MSC transmits a DT (Direct Transfer) MM (Mobility Management): Authentication message to the terminal to perform a terminal identification process, and if a security setting is required, a DT MM: Security Mode message is transmitted to the terminal. step;
When the process for authentication and security between the MSC and the terminal is completed, the MSC transmits a DT CM (Connection Management): Service Accept message to the terminal to allow the terminal to access the network. step;
Transmitting, by the terminal, a DT: Call Setup message to the MSC to perform a voice call setup process, and then transmitting a DT: Call Proceed message and a DT: Alert call setup message to the MSC;
Sending, by the MSC, a radio bearer assignment message to the aggregator to notify the allocated voice channel information;
When the aggregator notifies that the channel set for the LCP is a voice traffic type, the LCP transmits an RRC: Radio Bearer Setup message to the terminal to notify that the set radio channel of the terminal is for voice ; And
When the terminal prepares to make a voice frame, and then transmits a Radio Bearer Setup Complete message to the LCP, the LCP transmits a Radio Bearer Assignment Complete message to the aggregator, the aggregator is the MSC Transmitting a Radio Bearer Assignment Complete message to the terminal to complete a link establishment operation between the terminal, the aggregator, and the MSC for the voice traffic.
Wireless service interworking method of the cellular network and WLAN network further comprising.

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