JP2007295207A - Mobile communication system, and handover method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform stabilized handover control easily and quickly in a mobile communication system. <P>SOLUTION: The mobile communication system has one or more base stations, and a host apparatus connected with one or more base stations and a core network. The host apparatus has a functional section for managing wireless link information required for establishing a wireless link, and a functional section for notifying the wireless link information to the base station. Each of the one or more base stations has a functional section for establishing a wireless link with the base station, based on the wireless link information notified from the host apparatus; and a functional section for notifying information representative of the state of the mobile station after establishing the wireless link. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a mobile communication system and a handover method including a base station and a host device that aggregates the base stations.

  In a conventional mobile communication system such as a personal digital cellular (PDC) system or FOMA (registered trademark) system, mobile station control such as call connection and handover is performed by a host device that controls a plurality of base stations. The host device is, for example, a radio network controller (RNC). In this method, even if a mobile station moves at high speed in an area composed of a plurality of cells, handover control is performed by the same host device. Therefore, simple and stable handover control can be performed even during high-speed movement. This type of mobile communication system is described in Non-Patent Document 1, for example.

  However, in this method, all the control related to the handover is performed by the host device, and therefore, the host device performs control even in the handover without changing the base station. Therefore, this method is not necessarily advantageous from the viewpoint of promptly performing handover. In particular, when a handover between sectors belonging to the same base station is performed, control delay may be regarded as a problem.

  On the other hand, from the viewpoint of shortening the call connection time, it is also conceivable that the base station controls call connection and handover without depending on the host device. However, in this method, every time handover between base stations is required, the control start point of handover must be transferred from the transfer source base station to the transfer destination base station. For this reason, the control signal amount and the control burden increase, and this method is not advantageous from the viewpoint of performing simple and stable control.

In recent years, the scope of mobile communication services has been expanding. For example, it is expected that high throughput is required although mobility is low, such as indoor mobile communication, and mobility is very low, such as vending machines. Even mobile communication services are becoming the target. Therefore, it is desired that an effective handover is performed in a system including various mobile objects.
3GPP standardization specifications TS25.331, TS25.401

  An object of the present invention is to provide a mobile communication system and a handover method that perform stable handover control simply and quickly.

  In the present invention, a mobile communication system having one or more base stations, one or more base stations, and a host device connected to a core network is used. The host device includes a functional unit that manages radio link information necessary for establishing a radio link, and a functional unit that notifies the base station of the radio link information. Each of the one or more base stations includes a functional unit that establishes a radio link with a mobile station based on radio link information notified from the host device, and a state that indicates a state of the mobile station after the radio link is established And a function unit for notifying the host device of information.

  According to the present invention, stable handover control can be performed easily and quickly.

  In the present invention, a mobile communication system having a plurality of base stations and a host device that aggregates the plurality of base stations is used. The host device has a function of notifying the base station of the radio link information in addition to the function of managing the radio link information necessary for establishing the radio link. The base station has a function of determining configuration parameters of the radio link based on the radio link information notified from the host device, and establishing and maintaining the radio link with the mobile station.

  In such a mobile communication system, the host device manages the radio link configuration information of the connected mobile station. When handover between base stations is required, the handover source base station notifies the host device of status information at the time of handover (information indicating the status of the mobile station that can change after establishing the radio link). The host device notifies the handover destination base station of the radio link information including the notified state information and radio link configuration information (information indicating a policy for establishing a radio link). The handover control requires the latest information (latest radio link information) of both the radio link configuration information and the state information. The handover destination base station determines a radio link configuration parameter based on the notified latest radio link information, and establishes a radio link with the mobile station. Among the radio link information, the radio link configuration information is managed by the higher-level device, and thus does not need to be managed by the base station. Therefore, it is not necessary for the radio link configuration information to be transferred from the base station to the higher-level device and between the base stations during the inter-base station handover. For this reason, the amount of control signal and the control burden at the time of handover between base stations are reduced.

  On the other hand, in the handover at the same base station, the base station does not have to report the status information to the host device. The base station performs intra-cell handover based on the stored radio link configuration information and the latest state information. Handover within the same cell that does not straddle a base station can be performed by closing the base station.

  FIG. 1 shows a configuration example of a mobile communication system 100 according to an embodiment of the present invention. The mobile communication system includes a mobile station 101, a base station 102, a host device 103, and a network 104.

  The base station 102 has a function of establishing and maintaining a wireless link and performing wireless communication with the mobile station 101. The base station also has a function of performing wired communication with the host device 103. The base station 102 relays user data in the wired section and the wireless section. Regarding control of call connection and handover, the base station 102 has a function of controlling handover at least under the same base station. The base station 102 establishes a radio link with the mobile station by exchanging radio link information (information necessary for establishing a radio link) with the host device.

  The host apparatus 103 has a function of controlling a plurality of base stations 102 and may be configured by a radio network controller (RNC). The radio base station 102 and the RNC are also referred to as a radio access network device (RAN) as a whole. The host device 103 relays user data between the base station 102 and the network 104. The host device manages the radio link information and communicates the radio link information with the base station 102 as necessary.

  The network 104 is, for example, a network based on the Internet protocol (IP), and is connected to a core network including a subscriber information management device and a service control device.

  FIG. 2 is a functional block diagram of a wireless access device according to an embodiment of the present invention. The radio access device includes a host device and a base station device. In FIG. 2, a radio link information management unit 201 and a radio link information notification unit 204 are depicted in the host device. The host device manages the mobile station based on the radio link information managed by the radio link information management unit 201. The radio link information includes radio link configuration information 202 and status information 203.

  FIG. 3 shows a specific example of radio link configuration information and status information. The radio link configuration information indicates a policy (may be called a condition or a guideline) necessary for establishing the radio link. This information is collected from mobile stations, subscriber information management devices, service control devices, and the like. The radio link configuration information includes, for example, contract information related to a user's contract form, service information related to a service received by the user, quality of service (QoS) information required for communication, security information related to an authentication method and a secret key applied to the user, etc. Etc. may be included. Note that the categorization of these illustratively listed information is not exact. These pieces of information have a semi-fixed property that is not frequently changed. The radio link configuration information is also information determined before establishing the radio link.

  The status information indicates the status of the mobile station or radio link that can change after the radio link is established. The state information may include information indicating whether the mobile station is in an operation mode for battery saving (intermittent reception state), for example. Further, the status information may include information indicating the protocol status of each layer such as acknowledgment (ACK, NACK) of the retransmission protocol. Since the status information changes more frequently than the radio link configuration information, the status information is managed at the base station. Accordingly, the state information stored in the host device is updated with the state information notified from the base station.

  In FIG. 2, a radio link establishment & maintenance unit 205 and a state information notification unit 206 are depicted in the base station. The radio link establishment & maintenance unit 205 determines specific parameters for configuring the radio link based on the radio link information from the host device, and establishes the radio link with the mobile station. The state information notification unit 206 notifies the higher-level apparatus of the radio link information (state information) as necessary (typically, when the base station becomes a transition source of handover between base stations).

[Operation Example 1]
When the mobile station is newly connected to the base station, this is notified to the host device. The host device notifies the base station of radio link information (radio link configuration information) related to the mobile station. Based on the notified radio link information, the base station determines specific parameters for configuring the radio link, and establishes the radio link with the mobile station. As a result, resource blocks (frequency), subframes, etc. used for wireless communication are scheduled. Thereafter, the base station manages the status information and reports it to the host device as necessary.

[Operation example 2]
FIG. 4 is a diagram showing a procedure for inter-base station handover. First, the handover source base station (HO source base station) determines whether or not there is a trigger for handover between base stations. When it is confirmed that the inter-base station handover is necessary, the fact is notified to the host device. In this case, the HO former base station notifies the host device of status information regarding the mobile station (1). The host device updates the status information related to the mobile station with the status information notified from the base station (2). The host device notifies the handover destination base station (HO destination base station) of the radio link information including the radio link configuration information about the mobile station and the updated status information (3). The HO-destination base station sets various parameters of the radio link according to the radio link information notified from the host device, and establishes a radio link related to the mobile station (4).

  When the base station confirms that a handover at the same base station is necessary, the status information is not reported to the host device. The radio link configuration information related to the mobile station is notified from the host device to the base station at least when the mobile station is connected to the base station. Therefore, at the time of handover within the same base station, the host device does not need to notify the base station of the radio link configuration information again. The base station can perform handover without changing the base station using the stored radio link configuration information and the state information managed by the base station.

  As described above, according to the embodiment of the present invention, the radio link configuration information among the information (radio link information) necessary for establishing the radio link is managed by the host device. Link configuration information need not be transferred between base stations. Dynamically changing state information may be transferred between base stations. Since the radio link establishment & maintenance unit 205 is prepared in the base station, it is not necessary for the host device to be involved in the case of a handover that does not cross the base station, and the handover control can be completed by closing to the same base station. Control delay can be effectively suppressed.

It is a figure which shows the structural example of the mobile communication system by one Example of this invention. 1 is a functional block diagram of a radio access device according to an embodiment of the present invention. FIG. It is a figure which shows the specific example of radio | wireless link information. It is a figure which shows the procedure of the handover between base stations.

Explanation of symbols

101 Mobile station
102 base station
103 Host device
104 network
201 Radio Link Information Management Department
202 Radio link configuration information
203 Status information
204 Wireless link information notification unit
205 Radio Link Establishment & Maintenance Department
206 Status information notification section

Claims (5)

In a mobile communication system having one or more base stations and one or more base stations and a host device connected to a core network,
The higher-level device has a function unit that manages radio link information necessary for establishing a radio link, and a function unit that notifies the base station of the radio link information,
Each of the one or more base stations includes a functional unit that establishes a radio link with a mobile station based on radio link information notified from the host device, and a state that indicates a state of the mobile station after the radio link is established A mobile communication system comprising: a functional unit that notifies information to a host device. The mobile communication system according to claim 1, wherein the radio link information includes radio link configuration information indicating a policy for establishing a radio link in addition to the state information. The wireless link configuration information includes one or more of information indicating a contract content by a user, service information indicating a service type, information indicating service quality (QoS), and security information related to security. Mobile communication system. The mobile communication according to claim 2, wherein the status information includes one or more of information indicating whether or not the mobile station is in a battery saving state when waiting and information indicating protocol status of one or more layers. system. A handover method used in a mobile communication system having one or more base stations and a host device connected to a core network, the host device managing radio link configuration information indicating a policy for establishing a radio link The handover method is
State information indicating the state of the mobile station that changes after the establishment of the radio link is notified from the handover source base station to the host device;
Radio link information including the state information and radio link configuration information is notified from the higher-level device to the handover destination base station;
A step of establishing a radio link between the handover destination base station and the mobile station based on the radio link information notified from the host device;
A handover method characterized by comprising:

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