JPH06315186A - Hand off method - Google Patents

Abstract

PURPOSE:To make it possible to surely select a hand off destination connection device within short time at the time of a hand off in a time division multiplex system communication system of mobile object where a multi-zone is composed of plural radio connection devices and the communications with plural moving machines are performed. CONSTITUTION:A radio line controller 13 is provided with a radio channel storage part 20 storing the slot and carrier using status of each connection device 10, 11 and 12 and a priority determination part 21 referring to the data of the radio channel storage part 20, judging the slot use status and giving the priority to the connection device performing a radio communication channel monitoring, and when a hand off destination connection device is selected, the retrieval of the hand off destination connection device is performed according to the preferential obtained in the priority determination part 21.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a handoff method in a time division multiplexing mobile communication system in which a plurality of wireless connection devices constitute a multizone and communicates with a plurality of mobile devices, and more particularly to a handoff method. The present invention relates to a method of selecting a handoff destination connection device by monitoring a wireless communication channel which is a target of the above with the connection device.

[0002]

2. Description of the Related Art In recent years, the spread of mobile communication has been remarkable. In order to meet the increasing demand, development of a digital mobile communication system in place of the conventional analog system has been actively promoted, and in particular, a time division multiplex mobile communication system is becoming a reality. Less than,
A handoff method in a conventional time division multiplexing mobile communication system will be described with reference to the drawings. First, the configuration of the mobile communication system will be described with reference to FIG. In FIG. 6, reference numeral 31 is a wireless line control device for performing exchange control between the general public or another mobile communication system and an in-system wireless line, mobile management of the mobile device, and wireless management of the system, and 32, 33, 34, 35 are Under the control of the wireless line control device 31, a connection device which determines and opens a wireless line with a mobile device and monitors a wireless channel, 36, 37, 38,
39, 40 are connecting devices 32, 33, 3 while moving in the system
Mobile stations 41, 42, 43, and 44 that communicate with each other via 4, 35 and the wireless line control device 31 are wireless zones set for the connection devices 32, 33, 34, and 35, respectively.

Next, the configurations of the conventional connection device and wireless line control device will be described with reference to FIG. The configuration of the mobile device will not be described because no particular need is recognized. Reference numerals 50, 51 and 52 are connection devices for setting / opening a wireless line and monitoring a wireless channel under the control of a wireless line control device, which will be described later, and 53 is a general public network or another mobile communication system and a device in the system. A wireless line control device for performing exchange control with a wireless line and mobile unit movement management and wireless management, 54 is inside the wireless line control device 53, and connection devices 50, 5
An extension interface unit for interfacing with 1 and 52 for wired data transmission, 55 an exchange unit for exchanging a station line and an extension, 56 an exchange control unit for controlling the exchange unit 55, and 57 a wireless line control device 53. There is a station line interface section for interfacing with a station line inside the terminal, and 58 is a wireless control for performing mobile management / wireless management of the mobile device by communicating with the connection devices 50, 51, 52 through the extension interface section 54. Reference numeral 59 denotes a connection device arrangement storage unit that stores the positional relationship between the connection devices 50, 51 and 52 and is referred to by the wireless control unit 58 at the time of handoff. Here, for the sake of simplification, the number of connection devices is three, but in reality, more connection devices are wireless line control devices.
Connected to 53.

With respect to the conventional connection device and wireless line control device configured as described above, the operation during handoff will be described with reference to FIGS. 7 and 8. It is assumed that a mobile device (not shown) is connected to the general public network via the connection device 50. In this case, the communication signal with the connection device 50 is connected to the general public network via the extension interface unit 54, the exchange unit 55, and the office line interface unit 57.
The exchange unit 55 and the office line interface unit 57 are exchange control units.
The extension interface unit 54 is controlled by the wireless control unit 58. A control signal with the connection device 50 is input to and output from the wireless line control unit 58 via the extension interface unit 54. A mobile device (not shown) communicating with the connection device 50 via a wireless line detects quality deterioration of the wireless communication channel and transmits a handoff process start request to the connection device 50. The connection device 50 transmits a handoff process start request to the wireless control unit 58 via the extension interface unit 54. Therefore, the wireless control unit 58 starts the handoff process. The wireless controller 58 first selects a peripheral connection device.
(S ₅₀ ) (in the following figures, the connecting device is abbreviated as CS). The peripheral connection device is a connection device that can be considered as a handoff destination from the connection device that has made the handoff request,
In this case, the connection device 50 that has issued the handoff process start request
The peripheral connection device will be selected. The wireless control unit 58 selects the peripheral connection device by reading the data in the connection device arrangement storage unit 59. The wireless control unit 58 monitors the wireless communication channel used by the mobile device that has issued the handoff process start request, by all the peripheral connection devices. A method for monitoring the wireless communication channel will be added. The wireless control unit 58 issues a wireless communication channel monitor request by designating the carrier slot of the wireless communication channel to the connection device which wants to monitor the wireless communication channel via the extension interface unit 54 ( _S52 ) (Fig. In the description, the wireless communication channel is abbreviated as TCH). The connection device, which has received the wireless communication channel monitor request, monitors according to the slot specification status of the connection device. That is, when the same slot as the wireless communication channel to be monitored is not used, the monitoring is performed as it is, and when it is used, the wireless communication channel is switched and then monitored. If all slots are in use, the handoff is not performed and monitoring is not performed. After transmitting the wireless communication channel monitor request, the wireless control unit 58 waits for the monitoring result from the connection device to be transmitted (S ₅₃ , S ₅₄ ), and times out if the monitoring result cannot be received after a certain period of time. age
( _S55 ), the next connected device is monitored. After repeating the same monitoring for each peripheral connection device, the monitor results are compared (S ₅₆ ), and if there is a connection device to be handed off, carrier sensing is performed by that connection device and an empty channel is searched for. , Perform handoff (S ₅₇ , S
₅₈ , S ₅₉ ). When there is no connecting device to be handed off, the wireless control unit 58 notifies the connecting device 50 of handoff refusal via the extension interface unit 54 ( _S57 , _S60 ). In the above description, the handoff process start request is transmitted from the mobile device, but the same process is performed when the connection device detects the deterioration of the wireless communication channel quality and sends the handoff process start request.

[0005]

However, in the above handoff method, there is a problem that the quality of selection of the peripheral connection device largely determines whether or not the handoff destination connection device can be selected and the handoff processing time. It is an object of the present invention to solve the above problems and to provide a handoff method that can reliably select a handoff destination connection device within a short time without being influenced by the selection of peripheral connection devices.

[0006]

In order to achieve the above object, the present invention provides a wireless channel control device, a wireless channel storage unit for storing the slot and carrier usage status of each connection device in each connection device, and a wireless channel storage unit. A priority order determination unit is provided for referring to the data in the channel storage unit to determine the slot usage status and prioritize the connection device that monitors the wireless communication channel.

[0007]

According to the present invention, when the handoff destination connecting device is selected, the handoff destination connecting device can be searched according to the priority order obtained by the priority order determining unit.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Since the system configuration is the same as the conventional one, the description is omitted. FIG. 1 is a block diagram showing the configurations of a connection device and a wireless line control device in an embodiment of the present invention. The configuration of the mobile device will not be described because no particular need is recognized. In FIG. 1, 10, 11,
Reference numeral 12 is a connection device for setting and releasing a wireless line and monitoring a wireless channel under the control of a wireless line control device described later, and 13 is a switching control between a general public network or another mobile communication system and an in-system wireless line. Also, a wireless line control device for performing mobility management and wireless management, 14 is an extension line interface unit inside the wireless line control device 13 for interfacing with the connection devices 10, 11, 12 for wired data transmission, and 15 is a station line and an extension line. An exchange unit for exchanging the exchange unit, 16 an exchange control unit for controlling the exchange unit 15, 17 an internal line interface unit for interfacing with an internal line existing inside the wireless line control device 13,
18 is a connecting device 10, 1 via the extension interface unit 14.
A wireless control unit that performs mobile management and wireless management of mobile devices by communicating with 1 and 12, 19 is a connection device arrangement storage unit that stores the positional relationship between the connection devices 10, 11 and 12, and 20 is the connection device 10 and
A wireless channel storage unit that stores the wireless channel usage status of each connection device reported from 11 and 12, 21 refers to the connection device arrangement storage unit 19 and the wireless channel storage unit 20, and prioritizes and monitors the wireless communication channel monitor. It is a priority order determination unit that performs grouping of connected devices that perform the above. Here, for the sake of simplification, the number of connecting devices is three, but in reality, more connecting devices are connected to the radio network controller 13.

With respect to the connection device and the wireless line control device configured as described above, the operation at the time of handoff will be described with reference to FIGS. 1 to 5. Mobile
It is assumed that (not shown) is connected to the general public network via the connection device 10. In this case, the communication signal with the connection device 10 is connected to the general public network via the extension interface unit 14, the exchange unit 15, and the office line interface unit 17. The exchange unit 15 and the office line interface unit 17 are controlled by the exchange control unit 16, and the extension interface unit 14 is controlled by the wireless control unit 18. A control signal with the connection device 10 is input to and output from the wireless control unit 18 via the extension interface unit 14. Further, unlike the conventional example, the carriers and slots of the radio channels used in the connection devices 10, 11, 12 are transmitted as control signals to the radio control unit 18 via the extension interface unit 14. The wireless control unit 18 stores this data in the wireless channel storage unit 20 and updates it every time the wireless channel usage status of the connection device changes.

A mobile device (not shown) communicating with the connection device 10 via the wireless line detects deterioration of the quality of the wireless communication channel and transmits a handoff process start request to the connection device 10. The connection device 10 transmits a handoff process start request to the wireless control unit 18 via the extension interface unit 14. Therefore, the wireless controller 18 starts the handoff process. The wireless controller 18 first performs peripheral connection selection and grouping (S ₁ ) (hereinafter, the connecting device is abbreviated as CS in the drawing). The peripheral connection device is a connection device that can be considered as a handoff destination from the connection device that has made the handoff request, and in this case, the peripheral connection device of the connection device 10 that has made the handoff process start request will be selected. . However, as will be understood later, more connection devices can be selected as peripheral connection devices than in the conventional example, and in some cases, all connection devices can be selected as peripheral connection devices. Here, grouping means the connection device layout storage unit
With respect to the peripheral connection device determined from 19, the priority order determination unit 21 assigns a priority to the peripheral connection device stored in the wireless channel storage unit 20 according to the slot usage status of each connection device.

With reference to FIG. 5, a more specific description of grouping will be given. Although there are four slots in FIG. 5, the following description is not limited to the number of slots. If the handoff source connection device is communicating with the mobile device that has transmitted the handoff processing start request in slot 2,
Group 1 is a connection device that can monitor its wireless communication channel as it is. In this case slot 2
Peripheral connection devices that are not used belong to group 1.
Group 2 is a peripheral connection device that cannot monitor the handoff target wireless communication channel as it is, but can be monitored by switching the handoff target wireless communication channel. Group 3 is a peripheral connection device that has unused slots but does not belong to groups 1 and 2, and is a peripheral connection device that can be monitored by switching the slot of the wireless communication channel of the connection device. It becomes difficult to monitor the handoff target wireless communication channel in the order of group 1, group 2, and group 3. Therefore, the monitoring is started from the peripheral connection device that can be monitored more easily. Peripheral connection devices that are using all slots are not monitored because they cannot be connected to the handoff destination connection device. After grouping, the wireless communication channel is monitored. Group 1, group 2, and group 3 are performed in this order. The process ends when the handoff destination connection device is found. In addition, by simultaneously performing wireless communication channel monitoring on a plurality of peripheral connection devices belonging to the same group, it is possible to monitor the handoff target wireless communication channel for a larger number of connection devices in a short time. .

A detailed description will be given below by following the flowcharts of FIGS. 2 to 4. After the peripheral connection devices are divided into groups, the presence / absence of peripheral connection devices belonging to the group 1 is confirmed (S ₂ ). If not, the process proceeds to the wireless communication channel monitor by group 2. When there is a connecting device belonging to group 1, the wireless control unit 18 requests the connecting device of the group 1 via the extension interface unit 14 to monitor by designating the carrier and slot of the wireless communication channel ( S ₃ ). The wireless controller 18 receives and determines the monitor result from the group 1 connection device (S ₅ ). If the monitor result is suitable as a handoff destination connection device,
And executes a handoff by using the same carrier slot a radio communication channel performing the monitor (S _9),
And ends the update radio channel information (S ₁₀₎ the hand-off process. Here, what is different from the conventional example is that handoff is performed using the same carrier and slot as the monitored wireless communication channel without performing empty channel search by carrier sense. Since the monitored wireless communication channel becomes an empty channel after handoff, it is used for handoff without performing carrier sense. Therefore, no time is required to search for an empty channel. If the handoff destination connection device is not found within a fixed time, it is determined that a time-out has occurred (S ₆ ) and the process proceeds to monitor the group 2 connection device.

Next, the monitor by the group 2 connection device will be described. First, the presence / absence of a group 2 connection device is confirmed (S ₁₁ ). If not, the process proceeds to the wireless communication channel monitor by group 3. When there is a connecting device belonging to group 2, the wireless control unit 18 uses the extension interface unit.
The slot is specified and the slot switching is requested to the connection device 10 via 14 (S ₁₂ ). After the completion of the slot switching, the wireless control unit 18 requests the monitor of the connecting device of the group 2 via the extension interface unit 14 by designating the carrier and the slot of the wireless communication channel.
(S _13). The wireless controller 18 receives and determines the monitor result from the group 2 connection device (S ₁₅ ). If the monitor result is suitable as the handoff destination connection device, handoff is executed using the same carrier and slot as the radio communication channel monitored as in the case of group 1, the radio channel information is updated, and the handoff process ends. (S ₂₀ , S ₂₁ , S ₂₂ ). If the handoff destination connection device is not found within the fixed time, it is determined to be time out (S ₁₆ ). Connection device 10 that received the request to start the handoff process
If there is a slot whose slot can be switched, the same monitor is repeated. (S ₁₈ ). If the handoff destination connection device is still not found, the wireless channel information is updated, and then the process proceeds to monitoring by the group 3 connection device (S ₁₉ ).

Next, the monitor by the group 3 connection device will be described. First, to check for Group 3 connection device (S _23). If not, the wireless controller 18 notifies the mobile device that has transmitted the handoff processing start request via the extension interface unit 14 and the connection device 10 of handoff refusal ( _S35 ). If there is a connecting device belonging to group 3, the wireless control unit 18 requests slot switching from the connecting device of group 3 via the extension interface unit 14 (S ₂₄ ). After switching slots, the wireless controller
18 to the connection device of a group 3 via the extension interface unit 14, a wireless communication channel of the carrier, by specifying a slot to request a monitor (S _25). Wireless controller 18
Receives and judges the monitor result from the group 3 connected device (S ₂₇ ). If the monitor result is suitable as the handoff destination connection device, handoff is executed using the same carrier and slot as the radio communication channel monitored as in the case of group 1, the radio channel information is updated, and the handoff process ends. (S ₃₂ , S ₃₃ , S ₃₄ ).
If the handoff destination connection device is not found within a certain period of time, it is determined as a time-out (S ₂₈ ), and the wireless control unit 18 sends a handoff process start request via the extension interface unit 14 and the connection device 10 to the mobile device. notifies the handoff rejected for, after updating the radio channel information and ends the handoff process (S _30, S _31). In the above description, the handoff process start request is transmitted from the mobile device, but the same process is performed when the connection device detects the deterioration of the wireless communication channel quality and sends the handoff process start request.

[0015]

As is apparent from the above embodiments, the present invention refers to the radio channel storage unit for storing the slot and carrier usage status of the connection device in the radio network controller and the data in the radio channel storage unit. By providing a priority determination unit that prioritizes the connection devices that judge the slot usage status and monitor the wireless communication channel, the handoff destination connection device can be reliably connected within a short time regardless of the selection of peripheral connection devices. It has the effect that can be selected.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a connection device and a wireless line control device in an embodiment of the present invention.

FIG. 2 is a flowchart of a handoff method according to an embodiment of the present invention.

FIG. 3 is a flowchart of a handoff method according to an embodiment of the present invention.

FIG. 4 is a flowchart of a handoff method according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram of grouping of connection devices.

FIG. 6 is a configuration diagram of a mobile communication system.

FIG. 7 is a configuration diagram of a conventional connection device and wireless line control device.

FIG. 8 is a flowchart of a conventional handoff method.

[Explanation of symbols]

10, 11, 12, 32, 33, 34, 35, 50, 51, 52 ... Connection device,
13, 31, 53 ... Wireless line control device, 14, 54 ... Extension interface part, 15, 55 ... Exchange part, 16, 56 ... Exchange control part, 17 ... Station line interface part, 18, 58 ... Wireless control part, 19 , 59 ... Connection device arrangement storage unit, 20 ... Wireless channel storage unit, 21 ... Priority order determination unit, 36, 37, 38, 3
9,40 ... Mobile station, 41,42,43,44 ... Wireless zone.

Claims (3)

[Claims] 1. A wireless line controller for controlling wireless lines of a plurality of wireless zones; and a wireless line controller connected to the wireless line controller by wire to form the respective wireless zones, and frame synchronization can be established between the wireless zones. In a mobile communication system based on a time division multiplex system, which comprises a plurality of connection devices for transmitting and receiving radio signals and a plurality of mobile devices for communicating with the connection devices via a wireless line, the connection device is connected to the wireless line controller Wireless channel storage unit that stores the slot and carrier usage status of the wireless LAN, and a priority determination unit that prioritizes the connection device that performs communication channel monitoring by determining the slot usage status by referring to the data of the wireless channel storage unit And a handoff destination connection device is searched according to the priority order. 2. The handoff method according to claim 1, wherein the wireless communication channel monitor is requested at the same time to the connection devices having the same priority. 3. The handoff method according to claim 1, wherein after the handoff destination connection device is selected, the handoff is performed using the wireless communication channel monitored immediately before.