JP3335942B2 - Handoff control method in mobile communication - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a handoff control method in mobile communication, and more particularly to a handoff control method for shortening a connection time in a recalling type handoff during simplex communication in mobile communication.

[0002]

2. Description of the Related Art A channel specifying method in a conventional mobile communication system will be described with reference to FIGS. In the following description, the channel is expressed as ch. FIG. 1 is an example of a configuration diagram of a mobile communication system, and FIG. 7 is a sequence showing a state transition in a mobile station in a conventional recalling type handoff in the system of FIG. The channel designation message broadcast by the base station 1 broadcasts only the radio conditions used by the mobile stations 11 to 13 existing in the base station 1. The wireless receiving unit 54 in FIG.
Processes the received channel designation message in the control unit 55, and the communication channel (T_c in FIG. 7) allocated for communication.
The control unit 55 that has recognized h) issues a change instruction to the wireless transmission unit 53 and the wireless reception unit 54. The wireless transmission unit 53 and the wireless reception unit 54 control the designated communication channel by the control channel (C in FIG. 7).
_Ch), and establishes synchronization to enter a communication state.

When the mobile station 11 moves during the group simplex communication and changes the communication zone, the reception level is detected by the radio reception unit 54, and the level is detected as level deterioration by the level determination unit 56. At this time, the control section 55 searches for the frequency level of the control channel of the preset peripheral zone, and transmits the search result to the control section 55. The control unit 55 can determine which base station zone has been moved based on the search result. The control unit 55 that has recognized the movement destination zone sends the wireless transmission unit 53 and the wireless reception unit 5 to the control channel of the base station 2 that is the movement destination.
The frequency setting of No. 4 is switched.

The radio receiving unit 54 synchronizes with the control channel of the base station 2, collects information reported by the control channel of the base station 2, and transmits the information to the control unit 55. Then, the control unit 55 that has analyzed the information
Transmits a request message to the wireless transmission unit 53 in order to confirm the wireless conditions during which the group of the mobile stations 11 are communicating within the base station 2 to the wireless transmission unit 53. Then, the channel designation message request transmitted from the wireless transmission unit 53 is processed by the control station 100 via the base station 2 and is again transmitted from the base station 2 to the mobile station 11 as a channel designation message.

[0005] The mobile station 11 processes the channel designation message received by the radio receiving section 54 with the control section 55. The control unit 55 that has recognized the communication channel allocated for communication in the base station 2 issues a frequency change instruction to the wireless transmission unit 53 and the wireless reception unit 54. Then, the wireless transmission unit 53 and the wireless reception unit 5
4 switches from the control channel to the designated communication channel, establishes synchronization, and enters a communication state.

[0006]

However, in the above-mentioned conventional system, the mobile station needs to make a call again in order to confirm the radio conditions of the destination base station to the control station or the like. For this reason, when a mobile station in a communication state moves between zones, there occurs a problem that a handover time of communication returning to group simplex communication, that is, a so-called handoff time becomes longer.

[0007] The present invention has been made in view of such circumstances, and an object thereof is to provide a mobile station which does not switch between a control channel and a communication channel when moving to another base station zone. An object of the present invention is to shorten the connection time in handoff by directly establishing synchronization in a communication channel and entering a communication state.

[0008]

According to the present invention, there is provided a mobile communication system comprising: a base station in a system having a re-calling type handoff of simplex communication; By incorporating the radio conditions used in the station zone into the content of the channel designation message, handoff is performed directly in the communication channel without performing the handoff process in the control channel at the time of handoff. With this, when the mobile station moves to another base station, synchronization can be established in the communication channel, so that the communication state can be entered in a short time. The wireless condition is information necessary for performing communication, and includes a communication frequency, a scramble pattern, and a slot number (TDM in which one carrier is multiplexed).
In the case of the A system)-The call number assigned to the call in base station units.

In other words, the handoff control method in mobile communication according to the present invention is a handoff control method for a system having a re-calling type handoff during simplex communication in mobile communication. When the mobile station notifies the mobile station of the wireless condition of the communication channel by a channel designation message and performs inter-zone communication between a plurality of base station zones, each base station transmits the wireless condition notified by the control channel of its own base station. In the channel designation message in which is stored, the wireless condition of the communication channel assigned in the wireless communication zone of the other base station is assigned, and the channel designation message assigned with the wireless condition is sent to the mobile station in the wireless communication zone of the own base station. When the mobile station moves to another base station during the inter-zone simplex communication, the mobile station Based on the radio conditions of the other base stations included, characterized in that handoff in synchronization with the communication channel of the moved another base station.

[0010] In the above-mentioned handoff control method in mobile communication according to the present invention , the radio condition included in the channel designation message includes at least a communication frequency, a scramble pattern, and a carrier. It is characterized by information necessary for communication, including a slot number in the case of a TDMA system and a call number assigned to a call in base station units.

[0011] Further , the handoff control method in mobile communication according to the present invention is as described above , wherein the mobile station comprises:
A transmission / reception antenna for transmitting / receiving radio waves to / from a base station, a duplexer for controlling switching of transmission / reception waves, a radio transmission unit for transmitting transmission data, a radio reception unit for receiving reception data, A wireless communication unit configured to include a control unit for creating and analyzing data, a level detection unit for analyzing a reception level detected by the wireless reception unit, and a memory unit for temporarily storing data in the control unit; The receiving unit transmits the received data to the control unit, and the control unit
Analyzes the channel designation message, confirms the radio conditions assigned to the base station where the mobile station is located, issues instructions to the radio transmission unit and radio reception unit, and establishes synchronization and communication status under given radio conditions. So that the memory unit
The wireless condition of the communication channel in another base station assigned to the group of mobile stations is stored. Then, when the mobile station moves during the group simplex communication and changes the communication zone, the wireless receiving unit detects the reception level, the level determination unit detects this reception level as level deterioration, and furthermore, A frequency level of a control channel in the set peripheral zone is searched, and a search result is transmitted to the control unit. Based on the search result, the control unit determines a destination base station zone of the mobile station, and The control unit that recognizes the base station zone checks the wireless conditions for communication in the destination base station zone with respect to the memory unit, and instructs the wireless transmitting unit and the wireless receiving unit based on the confirmed wireless conditions. And changing from the communication channel of the base station zone before the movement of the mobile station to the communication channel of the base station zone after the movement, and establishing the synchronization of the mobile station and performing control so as to be in a communication state. Especially To.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. First, referring to FIG. 1, in the present invention, the radio conditions (f34) of the communication channel allocated by the base station 2 and the radio conditions (f3) of the communication channel allocated by the base station 3 are added to the channel designation message broadcast from the base station 1.
The feature is that the notification is performed including 6). here,
The channel designation message broadcast from the base station 1 is control channel_
f31, and the communication channel in the base station 1 is f32.

The mobile station 11 existing in the base station 1
By holding the content of the received channel designation message, even if the mobile station 11 moves between the zones to the base station 2 or the base station 3 during the simplex communication between the zones, the radio conditions of f34 and f36 are recognized in advance. Therefore, it is possible to synchronize with the communication channel at the moved base station without re-calling on the control channel. Therefore, there is no need to confirm the wireless condition by re-calling the control channel, and an effect that handoff can be performed in a short time is obtained.

FIG. 2 is a simplified flowchart from the connection request to the access permission state in the system shown in FIG. That is, in FIG. 2, the mobile station 11
2 shows a flow of a process until a request is made for group communication between the mobile stations 11 to 17 and a communication state is established.
FIG. 3 is an example showing the contents of the channel designation message transmitted in (8), (10), and (12) shown in FIG. further,
FIG. 4 is a flowchart showing a flow from the reception of the channel designation message to the return to the destination base station zone in the system of FIG. 1 until communication is restored. That is, it is a flowchart showing a flow from receiving a channel designation message in a mobile station, storing the message content, moving to another base station zone, synchronizing in a destination base station zone, and returning to a communication state. . FIG. 5 is a diagram showing a configuration inside the mobile station in the system of FIG. FIG. 6 is a sequence diagram showing a state transition inside the mobile station shown in FIG.

First, the configuration of the system shown in FIG. 1 will be described.
The base station 1 has a frequency f3 assigned to the base station 1.
A wireless communication zone 41 is formed by 1 · f32 and the like. Similarly, the base station 2 / base station 3 form a wireless communication zone 42 / wireless communication zone 43 with frequencies f33 / f34 / f35 / f36 and the like, respectively. Here, the mobile stations 11 to 17 are in the same group, the mobile stations 11 to 13 are registered in the zone of the base station 1, the mobile stations 14 to 16 are registered in the zone of the base station 2, The mobile stations 17 are registered in the zones of the base station 3 respectively.
The base station 1, the base station 2, and the base station 3 are connected to the control station 1 via the control line 21, the control line 22, and the control line 23, respectively.
Controlled from 00. Further, the mobile stations 11 to 17
The mobile station 11 has moved from the wireless communication zone 41 to the wireless communication zone 42 in the inter-zone simple communication state by the communication channels ch_f32, f34, and f36.

FIG. 2 shows that the mobile station 11 requests the base station 1 for group simplex communication between the mobile stations 11 to 17;
It shows the flow up to the communication state, which is originally shown in FIG.
The messages (1) to (15) include sequences such as ACK / NACK and confirmation of radio resources. In this flowchart, only the contents of the messages necessary for implementing the present invention will be described. (1) in FIG. 2 is a request signal for group simplex communication between the mobile station 11 and the mobile station 17 from the mobile station 11 to the base station 1. The mobile station 11 transmits (1) on the control channel at f31. In (2), the connection request signal is transferred from the radio unit to the control unit within the base station 1 and transmitted. (3) is a connection request signal transmitted from the control unit of the base station 1 to the control station 100 via the control line 21.

Next, a base station zone in which the group of the mobile station 11 is registered is selected in the control station 100, and a channel designation message signal of each base station is sent to the registered base stations 1 to 3. Data is transmitted to the control unit via the control lines 21 to 23 ((4), (5), (6)). In addition, each c
The h designation message signals (4), (5), and (6) include all the radio conditions of the communication channel transmitted by each base station. (7) is the message of (4) in the base station 1 (ch designation message)
Is a transfer signal from the control unit to the wireless unit. (9) ・ (1
Similarly, 1) is a transfer signal in (5) and (6) within the base station 2 and the base station 3. (8) is the control channel_f3 of the base station 1.
1 is a channel designation message for the mobile stations 11 to 13. This includes the communication channel (f3) of the base station 1.
In addition to the wireless conditions in 2), communication c between base station 2 and base station 3
The wireless condition of h (f34 · f36) is also included.

Similarly, (10) and (12) correspond to the mobile stations 14 to 1 in which the base station 2 and the base station 3 are registered in the own zone.
6 and a channel designation message to the mobile station 17, which is broadcast in addition to the wireless condition of the communication channel of the own station and the wireless condition of the communication channel of another base station. The mobile station that has received this channel designation message communicates with another base station.
The wireless condition is maintained, and when it moves during a call to another base station, it is used in the zone. (13), (14), and (15) show a state in which an access waiting signal from the mobile station is transmitted to the entire zone in the communication channel allocated by each base station. Also,
FIG. 3 shows channels transmitted by (8), (10), and (12) in FIG.
It is an example of the content of a specified message.

Next, the operation of the embodiment of the present invention will be described. First, the contents of the channel designation message transmitted in (8), (10) and (12) in FIG. 2 will be described with reference to FIG.
Octet 1 stores data necessary for recognizing the type of message to be transmitted. This is because there are many types of messages transmitted from the base station to the mobile station. In the case of the present invention, it is a channel designation message. Six octets of octet 2 to octet 7 store the radio conditions of the communication channel assigned by the base station 1. Octet 2 stores the base station number. Octet 3 stores the frequency code of the communication channel. Octet 4 stores a scramble pattern. Octet 5 stores the slot number. This is not necessary in the FDMA system, but it is necessary to recognize the used slot number in the TDMA system because the frequency is multiplexed.

The octet 6 stores the call number assigned by each base station. This is because the call number is arbitrarily assigned by each base station, so that the call number is different depending on the base station even if the call is for the same interzone communication. Before reporting the channel designation message, the control station needs to notify each base station of the group number of the mobile station that has requested inter-zone communication, and query the call number assigned by each base station. In response to the inquiry, the base station promptly returns the assigned call number to the control station and reserves the call number. The other elements of octet 7 store information elements that are unique to the system and are included in the channel designation message.

Examples of this information element include mobile station transmission power designation, originating mobile station number, communication mode, communication time limit, and the like. The above six octets are the radio conditions for one base station, and the six octets from octet 8 to octet 13 are loaded with the information element of the radio conditions of the base station 2, and octet 1
The information element of the radio condition of the base station 3 is placed in 4 to octet 19. In the following, the information elements of the radio conditions for n stations are placed in groups of 6 octets.

In FIG. 4, the mobile station 11 receives the channel designation message of (8) from the base station 1 on the control channel and transmits it to the control unit (16). In (18), the control unit of the mobile station stores the collected radio conditions of each base station. The operations of (16) and (18) are the same as (17) and (19) in the mobile station 12. After this,
The communication channels of the base station 1 and the base station 2 are in an access permission state ((1
3) ・ (14)) and the communication state is established. By moving, the mobile station 11 detects the level deterioration in (20).
1 reads the held communication conditions of the base station 2 to establish synchronization and return to the communication state in (21).

Next, the processing method in the mobile station will be described in detail with reference to FIGS. FIG. 5 shows the configuration inside the mobile station. The mobile station includes a transmission / reception antenna 51 for transmitting / receiving radio waves to / from the base station, a duplexer 52 for controlling transmission / reception wave switching, a radio transmission unit 53 for transmitting transmission data, Wireless receiving unit 54 for receiving
And a control unit 55 for creating and analyzing transmission / reception data, a level detection unit 56 for analyzing the reception level detected by the wireless reception unit 54, and a memory unit 57 for the control unit 55 to hold temporary data. I have.

In FIG. 6, radio receiving section 54 having received the channel designation message transmits received data to control section 55. The control unit 55 analyzes the channel designation message, confirms the wireless conditions assigned to the base station where the mobile station 11 is located, issues an instruction to the wireless transmitting unit 53 and the wireless receiving unit 54, and establishes synchronization under the given wireless conditions. -Control to be in communication state. Further, the wireless condition of the communication channel in another base station assigned to the group of the mobile station 11 is stored in the memory unit.

When the mobile station 11 moves during the group simplex communication and changes the communication zone, the reception level is detected by the radio reception unit 54, and the level is detected as the level deterioration by the level determination unit 56. At this time, the control section 55 searches for the frequency level of the control channel of the preset peripheral zone, and transmits the search result to the control section 55. The control unit 55 can determine which base station zone has been moved based on the search result. The control unit 55 that has recognized the movement destination zone stores in the memory unit 5
7 to confirm the wireless conditions at the time of communication in the destination zone. The wireless transmission unit 53 and the wireless reception unit 5
4, the communication channel of the zone before the movement is changed to the communication channel of the new zone, and control is performed so that synchronization is established / communicated.

The embodiment described above is an example for describing the present invention, and the present invention is not limited to the above-described embodiment, and various modifications are possible within the scope of the invention. is there. For example, although the basic configuration is the same as that of the above-described embodiment, the management of the communication state by the control station 100 as the system configuration example of FIG. It is needless to say that the present invention can be applied even if the system configuration is such that the communication station 3 manages the communication state and the control station 100 only manages the wired connection lines with the base station 1, the base station 2, and the base station 3. Absent. Further, in the above-described embodiment, the control channel and the communication channel have been described as different frequencies.
The present invention is also applicable to a TDM system in which a control channel and a communication channel are allocated at the same frequency.

[0027]

As described above, according to the present invention,
The connection / confirmation time due to re-calling can be saved. Therefore, even if the mobile station moves to another base station zone in the communication state, the communication state can be returned to the communication state in a shorter time than before. Further, it is possible to reduce the traffic of the control channel for the infrastructure equipment including the base station.

[Brief description of the drawings]

FIG. 1 is an example of a configuration diagram of a mobile communication system.

FIG. 2 is a simplified flowchart from a connection request to an access permission state in the system shown in FIG. 1;

FIG. 3 shows channels to be transmitted in (8), (10), and (12) shown in FIG.
It is an example showing the contents of a specified message.

FIG. 4 is a flowchart showing a flow from the reception of a channel designation message to the return to a destination base station zone in the system shown in FIG. 1 until communication is restored.

FIG. 5 is a diagram showing a configuration inside a mobile station in the system of FIG. 1;

FIG. 6 is a sequence chart showing a state transition inside the mobile station of FIG. 5;

FIG. 7 is a sequence diagram showing a state transition in a mobile station in a conventional recalling type handoff in the system of FIG. 1;

[Explanation of symbols]

 1, 2, 3 ... base station 11, 12, 13, 14, 15, 16, 17 ... mobile station 21, 22, 23 ... control line f31, f33, f35 ... control channel (ch) f32, f34, f36 ... communication Channels (ch) 41, 42, 43 ... Wireless communication zone 100 ... Control station 51 ... Transmitting / receiving antenna 52 ... Duplexer 53 ... Wireless transmitting unit 54 ... Wireless receiving unit 55 ... Control unit 56 ... Level determining unit 57 ... Memory unit

Claims (2)

(57) [Claims] In a handoff control method for a system having a re-calling type handoff during simplex communication in a mobile communication, each base station moves a radio condition of a communication channel by a channel designation message before starting communication. In the case of performing the inter-zone communication between a plurality of base station zones, the base station includes, in a channel designation message storing radio conditions reported by the control channel of the base station, other base stations. Storing the wireless condition of the communication channel allocated in the wireless communication zone of
A channel designation message to which the radio condition is assigned is transmitted to a mobile station in a radio communication zone of the base station. When the mobile station moves to another base station during inter-zone simplex communication, based on the radio conditions of the other base stations included in the channel Assignment message to be aware, in synchronization with the communication channel of the moved another base station handoff, the radio condition included in the channel designation message, at least, Information necessary for performing communication including a communication frequency, a scrambling pattern, a slot number in the case of a TDMA system in which carriers are multiplexed, and a call number assigned to a call in base station units. handoff control method in a mobile communication you characterized. 2. The mobile station comprises: a transmitting and receiving antenna for transmitting and receiving radio waves to and from the base station; a duplexer for controlling transmission / reception wave switching; a radio transmitting unit for transmitting transmission data; A wireless reception unit that receives reception data; a control unit that creates and analyzes transmission / reception data; a level detection unit that analyzes a reception level detected by the wireless reception unit; and a memory in which the control unit temporarily holds data. And a wireless receiving unit configured to receive the channel designation message,
Transmitting received data to the control unit, the control unit analyzes the channel designation message, confirms a radio condition assigned to a base station in which the mobile station is located, the radio transmission unit and the radio reception unit , And controls to be in a synchronization established / communication state under given radio conditions, and the memory unit stores radio conditions of communication channels in other base stations allocated to the mobile station group. When the mobile station moves during the group simplex communication and changes the communication zone, the wireless reception unit detects a reception level, and the level determination unit detects the reception level as level deterioration, Further, the control unit searches for a frequency level of a control channel in a preset peripheral zone, and transmits a search result to the control unit. Based on the search result, the control unit The control unit, which has determined the destination base station zone, recognizes the destination base station zone and checks the wireless condition at the time of communication in the destination base station zone with respect to the memory unit. On the basis of the condition, to issue an instruction to the wireless transmission unit and the wireless reception unit, and, from the communication channel of the base station zone before the movement of the mobile station, to change the communication channel of the base station zone after the movement, and, 2. The handoff control method in mobile communication according to claim 1 , wherein synchronization is established between the mobile stations and control is performed so as to be in a communication state.