JPS59178828A - Channel selecting system in mobile communication - Google Patents

Abstract

PURPOSE:To attain connecting control even on a boundary line of zones and to select quickly a CH for talking by providing a common control channel (CH) to plural radio zones and a control CH exclusive for each base station and providing a time band for incoming signal and connection control for the latter. CONSTITUTION:The exclusive control CHs of radio zones A, B, C are expressed as fA, fB and fC, and the common control CH is expressed as fs. In a figure (a), 6 is a synchronizing signal and 7, 8 and 9 are exclusive control CH information signals for base stations 3a-3c. A detector 12 detects the synchronizing signal 6 in each base station (b), the location of a prescribed time slot is located and a gate 14 is opened to bring the mode to a transmission state. The said CHfs is received by a mobile station (c), the electric field strength is measured at each time slot from each base station, the value is compared to store the control CH information corresponding to the maximum value, the CH is switched to the exclusive control CH for the most suited base station, e.g., fA based on the information to receive the informing signal such as incoming signal or idle CH or the like. The CH is switched to the common control CH fs when the electric field strength is lower than the specified value or a prescribed time interval after the CH is switched to the exclusive control CH so as to confirm and zone in which the own station exists.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention provides a mobile station that switches between multiple wireless channels and has a service area of multiple zones9, and a base station is installed in each of these wireless zones. In addition, regarding a mobile communication system in which a control channel (carrier wave) is provided exclusively for communication connection i in addition to the communication channel, this control channel is especially used to establish a control channel exclusively for the base station in the wireless zone where the mobile station is located. The present invention also relates to a channel selection method that can quickly set a communication channel.

Prior Art and Problems In mobile communication systems that provide two-way communication services over a wide range, the service area is generally divided into multiple wireless zones and multiple wireless channels are all prepared. It is used to communicate with mobile stations. As such a mobile communication system, the car phone system is currently in practical use9, and the car phone system has a service area of 1 as shown in Figure 1.
Divide into multiple wireless zones A, B, and C. 1. Wireless base stations 3a, 3b, 3c "' in each wireless zone A, B, C"'
c).

For example, if the mobile station 5 moving in wireless zone A goes off-hook to make a call, the mobile station 5 automatically sends a calling signal via the control channel, and the calling signal is sent to the nearest station. It is received by a plurality of wireless base stations 3a to 3C. The radio base stations 3a to 3C add level information indicating the level to the received calling signal and transfer the signal to the radio network control station 4. Based on the level information, the radio network control station 4 finds the radio base station from which the calling signal could be received most strongly, and determines the radio base station (wireless zone) to be used (in this case, it is the radio base station 3a). , then selects an available empty channel at the wireless base station 3a. When an empty channel is selected, the radio network control station 4 specifies the channel to be used for the mobile station 5,
Thereafter, the mobile station 5 and the wireless base station 3a will be connected using all of their wireless channels.

In this way, the conventional method sets radio channels, but the radio network control station 4 determines the radio base station to be used based on level information from multiple radio base stations, and then determines which radio channels are available. Since the channel to be used is designated by selection, there is a drawback that a call cannot be connected in a short time, and the control sequence is complicated. Furthermore, a similar drawback occurred when receiving a call to a mobile station.

Another method of using the control channel is to use a different channel for each wireless zone. Conventionally, the method of using this type of control channel is that a mobile station memorizes the control channel to be used in advance, switches to the control channel kIil[Ii and receives it, compares the strength of the reception level, and determines the maximum Determine the base station that can receive signals at the same level as the optimal base station, and control the connection using the corresponding control channel?
It is common to do so.

In this usage method, when a mobile station leaves the radio zone of the base station, that is, when it moves, the reception level of the control channel has fallen below a predetermined level, and the mobile station The mobile station detects that it has left the wireless zone, and at this time, the mobile station sequentially switches to other control channels for reception, and selects a control channel that can be received on a control channel with a predetermined level or higher. Whenever a mobile station crosses a zone boundary, the mobile station searches for a control channel, which has the disadvantage that connection control, especially incoming calls to the mobile station, is impossible during this time.

Purpose of the Invention The present invention has a general configuration including a control channel common to a plurality of wireless zones and a control channel specific to each wireless zone, and in the common control channel, a time slot or a modulation frequency band corresponding to each base station is provided. Thus, a control channel dedicated to each base station is broadcast, and the control channel dedicated to each base station is characterized by providing a time slot for broadcasting an incoming signal and a time slot for broadcasting other signals, and the purpose is to: The object of the present invention is to quickly select a communication channel and to control the connection even when crossing the boundary of a wireless zone.

Structure of the Invention The present invention allows a mobile station to switch between and use a plurality of channels.
The applicable mobile communication system is a service area consisting of a plurality of wireless zones, a base station is installed in each wireless zone, and a control channel for exclusive communication connection is provided in addition to the communication channel. In such a mobile communication system, two types of control channels are provided: a control channel common to multiple wireless zones within a service area, and a control channel dedicated to each base station. The dedicated control channel has a time period for broadcasting incoming signals and a time period for broadcasting information on the connection control unit or available channels for calls, etc. Based on this broadcast information, the mobile station uses the control channel dedicated to the base station. You can know. In the common control channel, information regarding the control channel corresponding to each base station is transmitted in a format that does not interfere with each other, that is, each base station uses a different time slot (time length) of the common control channel. Each base station broadcasts information to mobile stations using different modulation frequency bands. In addition, the mobile station performs control exclusively for the zone in which it is receiving only during the time period when it broadcasts connection control or information on available channels for calls at fixed time intervals or when the signal level of the base station in the zone falls below a predetermined value. Switch the channel to a common channel and check the signal level (received field strength) of the time slot or frequency band signal corresponding to each base station.

The wireless zone in which the mobile station is located is determined by detecting the demodulated signal (demodulated signal, etc.), and a control channel dedicated to the base station of the wireless source 7 is selected based on broadcast information from the control channel.

Embodiment of the Invention As an embodiment of the present invention - time slot in C1 valley base station) T
A channel selection method using the h allocation method will be explained. In Figure 1, the service areas are A, B, and C.
It consists of three radio zones, each with one or a number of dedicated control channels (
(radio frequencies) are expressed as fp, fB, and fc, respectively. On the other hand, one or more control channels (radio frequencies) common to the entire service area are represented by f8. Although the common control channel f8 will be transmitted at the same frequency at each base station 3B=3c, measures will be taken to prevent interference by matching the radio frequency and the phase of the modulated signal. is common.

An embodiment of the present invention in a mobile communication system configured as described above is shown in FIG. FIG. 2 is an example of a time chart showing the signal relay operation of the control channel from the control station 4 in each of the base stations 3a to 3c. Control signals relayed to transmitters are shown for each base station 3a to 3c in wireless zones A, B, and C (base stations 3a, 3b+3c). In the figure, 6 is a synchronization signal for synchronizing each base station 3a to 3c, and 7, 8.9 are control channel information signals dedicated to each base station 3a to 3c in each wireless zone A, B, and C, respectively. be.

FIG. 3 is a block diagram of a control signal relay unit in the base stations 3a to 3c, in which 1o is a control signal input terminal of the control station 4, 11 is a control signal repeater, and 12 is a synchronization signal 6.
13 is a bit counter, 14 is a signal output gate, 15 is a control signal output terminal to the transmitter, and 16 is a signal output terminal for controlling transmission 0N10FF of the transmitter.

Note that in this embodiment, the transmitter is placed in a transmitting state during signal relay.

The operation of the base station will be explained below with reference to FIGS. 2 and 3.

The control signal transmitted from the control station 4 to each base station 3a to 3c is provided with a synchronization signal 6 indicating a time slot for broadcasting channel information at each base station 3a to 3c. 3c, based on this synchronization signal, it becomes possible for each base station 3a to 3c to know the position of a time slot determined in advance so as not to overlap. That is, in each base station 3, when the synchronization signal detector 12 detects this synchronization signal, the bit counter 13 activated at the same time as the synchronization signal detector 12 is activated.
By this, the position of a predetermined time slot can be known, thereby opening the signal output gate 14 and simultaneously putting the transmitter into a transmitting state from the signal output terminal 16.

When the signal transmission is completed, the bit counter 13f is activated and the above operation is repeated until the next transmission timing.

Note that this type of control signal needs to be transmitted simultaneously by each of the base stations 3a to 3c, as shown in FIG.

FIG. 4 is a block diagram of main parts showing an embodiment of a mobile station, in which 40 is an antenna, 41 is an antenna duplexer, 42 is a receiving demodulator, 43 is an AD converter, 44 is a receiving channel controller, 45 4 is a memory, 46 is a synthesizer section, 47 is a modulation transmitting section, 48 is a connection control section, and 49 is a telephone set.

Here, the reception demodulator 42 demodulates the received channel information and the reception channel controller 44 . In addition to the connection control unit 48, a reception level signal indicating the reception level is sent to the reception channel control unit via the AD converter 43, and in this reception channel control unit 44, the control channel with the maximum reception level, which will be described later, is identified. It is done.

FIG. 5 is an operation flowchart for location zone detection and switching between a common control channel and a zone-dedicated control channel in a mobile station, and the significance of each variable in the flow is as follows.

R2; Wireless zone number RZmaX; Maximum value LV of wireless zone number (RZ
); Electric field level measurement value LVmaX of wireless zone RZ
: Electric field level maximum value C) (I(RZ); Control channel information of radio sea/RZ CHIrnaX; Control channel information of radio zone with maximum electric field level The operation of the mobile station will be described below.

The mobile station first receives the common control channel f3'Jt,
Based on the synchronization signal 6 transmitted from each base station 3a to 3C, the received electric field strength is measured for each time slot in which control channel information is transmitted from each base station 3a to 3C, and the obtained received electric field strength value is are successively compared and control channel information corresponding to the maximum received field strength value is stored. Next, based on the control channel information, the optimum control channel dedicated to the base station (for example, 'A)K is switched to receive a notification signal such as the empty channel information signal for the incoming signal 2 call. After switching to the dedicated control channel of the base station in the zone in which it is located, at a certain time interval or when the received field strength falls below the specified value, it switches to the aforementioned common control channel fs and recognizes the zone in which the base station is located, Switching to a dedicated control channel of another base station is performed as necessary.

An example of the signal structure of the dedicated control channel at the base station in the zone is shown in FIG. In FIG. 6, CI) is an example of the signal configuration of the dedicated control channel fA in the base station in the zone where the mobile station 5 is located, and for convenience of explanation, an example of the signal configuration of the common control channel f8 is also shown in D and CID. It is. In addition, 17 is a frame synchronization signal, 18 is m incoming signals,
19 is n free channel information signals for communication, 20, 2
1, 2. ! are dedicated control channel information signals of each base station 3a to 3C in each wireless zone A, B, and C, respectively. A mobile station receiving a common control channel normally determines whether or not there is an incoming call to its own station by looking at the incoming call signal 18 shown on the CD in FIG. If there is no call, the next call idle channel information 19 is ignored and the next incoming call signal is waited for, and the same process is repeated until the own station receives a call. Incoming signal 18
When there is an incoming call to the own station, the call channel is selected based on the latest call free channel information obtained from the next call free channel information 19, and the connection with the base station is made on that channel. to start the call. Furthermore, when a call is made from a mobile station, a call channel is similarly selected based on the latest available channel information for calls, and a connection is made with the base station using the selected channel to start a call.

Next, the timing of switching to the common channel fS will be explained. As an embodiment of the present invention, when a mobile station determines the zone in which it is located, the base station sends a call to an empty channel 19.
A common control channel f is used only during the time period when
The operation of switching to 8 will be described. In FIG. 6, the mobile station first receives one dedicated control channel of C1), and after a certain time interval or when the received field strength falls below a specified value, the mobile station receives the frame synchronization signal F2 at the timing The signal is switched to the common control signal f8. After switching to the common control channel f8, after receiving the signal t-14 frames broadcasted on the common control channel f8, the location zone is determined, and the dedicated control channels fA and fB are switched.

Switch to either fc. At this time, the time length for receiving one or more frames on the common control channel f8 is the same as the synchronization signal F2 on the common control channel 8 (or fB, fc).
By making the length of time during which the free channel information for communication from 1 to 1 to the synchronization signal F1 is broadcasted shorter than the length of time, the mobile device can receive all incoming signals at all times.

Further, as another embodiment of the present invention, a common control channel f
There is also a method in which the modulation frequency band of s is divided for each base station and a dedicated control channel for each base station is broadcast in each modulation frequency band. FIG. 7 shows an example of the frequency distribution of the received demodulated signal of the common control channel f8 at the mobile station.
Ss and Sc are base stations 3a, respectively.

This is the modulation frequency band assigned to 3b and 3c.

Furthermore, a control channel dedicated to each base station is broadcast using each modulation frequency band SA, SB, and S.

DETAILED DESCRIPTION OF THE INVENTION As described in detail, the present invention provides a control channel common to a plurality of wireless zones and a control channel dedicated to each wireless zone, and a mobile station receives an incoming signal while receiving a control channel dedicated to the zone in which it is located. Since it is possible to switch to a common control channel outside the broadcast time period, measure the reception level from each base station, and select the optimal control channel dedicated to the base station, it is possible to control connections at wireless zone boundaries, In particular, this has the effect of preventing incoming call control from becoming impossible.

Furthermore, since the mobile station knows the zone in which it is located and the available channels for calls when a call is generated, it is possible to connect the call immediately, thereby reducing connection delays.

This has the advantage that the control sequence can be simplified.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram of the configuration of a system that implements all mobile communication methods, Figure 2 is an example of a time chart when a base station relays all common control signals in multiple wireless zones, and Figure 3 is a common control at the base station. FIG. 4 is a block diagram showing an embodiment of the signal relay section; FIG. 4 is a block diagram of the main part of the embodiment of the mobile station; FIG.
The figure is an operation flowchart for location zone detection and switching between a common control channel and a zone-dedicated control channel in a mobile station, and FIG. FIG. 7 is another embodiment of the present invention, and is an example of the frequency distribution of the received demodulated signal of the common control channel f8 at the mobile station. 1...Service area, 2...Wireless zone, 3a~
3C...Base station, 4...Radio line control station, 5...
Mobile station, 6... Synchronization signal for synchronizing each base station, 7.8° 9... Dedicated control channel for each base station in each wireless zone A, B, C, 10... Control station control signal input terminal from 11... control signal repeater, 12... detector for synchronization signal 6, 13... bit counter, 14...
- Signal output gate, 15... Control signal output terminal to the transmitter, 16... Signal output terminal for controlling all transmission 0N10FF of the transmitter, 17... Frame synchronization signal, 18...
・Incoming call signal, 19...Free channel for calling ≠ channel information signal,
20, 21, 22... Wireless zones A, B, C! Dedicated control channel information for each base station 3. Patent Applicant: Nippon Telegraph and Telephone Public Corporation Patent Attorney Kugobe Tamamushi (3 others) Figure 2 Figure 3

Claims (1)

[Claims] When a mobile station switches between multiple channels and its service area consists of multiple wireless zones, a base station is installed in each wireless zone and a control channel is provided for exclusive use of communication connections in addition to the communication channels. In a channel selection method in mobile communication, a control channel common to multiple radio zones within the service area and a control channel dedicated to each base station are provided as the control channel, and a time period and a time period for broadcasting an incoming signal to the dedicated control channel are provided. A time slot is provided for broadcasting connection control or free channel information for communication, etc., and on the common control channel, information regarding the control channel corresponding to each base station is broadcast to mobile stations in a format that does not interfere with each base station. , the mobile station detects the signal level corresponding to each base station by switching to the connection control or idle channel for communication at certain time intervals or when the signal level of the zone base station in which it is located falls below a predetermined value. 1. A channel selection method in mobile communications, characterized in that the wireless zone in which the mobile station is located is determined by determining the wireless zone in which the mobile station is located, and a control channel dedicated to a base station in the wireless zone in which the mobile station is located is selected based on broadcast information from the control channel.