JPH04111545A - Control channel constituting method for mobile communication - Google Patents

Abstract

PURPOSE:To efficiently use a radio frequency by preparing one radio frequency common to the whole of a service area only for a report control (BCCH) channel and transmitting a report signal from each base station to a mobile station with an independent random period. CONSTITUTION:Radio frequencies of the BCCH channel and an incoming control (PCH) channel are separated, and they are so arranged that they are used in common by all base stations in the service area. Since the radio frequency of the BCCH channel is given to all base stations in the service area in common, each base station sends a report signal with an independent random period so that the report signal sent from the base station does not collide with another. For the purpose of realizing this random transmission, each base station generates a transmission slot period T to count the transmission interval of the report signal. Base stations send report control signals at random intervals, and the reception side controls a maximum signal, which can be correctly received without collision, based on reception information. Thus, an idle communication channel is reported to the mobile station to improve the use rate of the radio frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of configuring a control channel in a mobile communication system.

(Prior art) As shown in Figure 1, the station configuration in a conventional mobile communication system consists of a mobile station, a base station that forms a wireless zone, and a wireless control station that centrally controls multiple base stations within a calling area. be done. Here, 1 to m are base stations, 10 is a radio control station, and 20
indicates a mobile station. Its control channel configuration (e.g., “Large-capacity mobile communication system wireless line control technology” Tsuken Jitsuho, vol.
35. No, 10.1986゜PPll-18)
is a broadcast control channel (BCCH) that broadcasts system information such as location information from multiple base stations to mobile stations.
Broadcasting Control Channel
el) and a paging control channel (PCH:P) that transmits paging signals from multiple base stations within the paging area to the mobile station.
There is also a base station individual control channel (SCCH: 5tan
d-alone Control Channel)
is provided. Regarding the radio frequencies of these control channels, BCCH and PCH channels are assigned in common to multiple base stations within a calling area, and 5CCH channels are individually assigned to each base station in consideration of repeated use of radio frequencies. .

The above BCCH channel is the first control channel that a mobile station acquires after turning on the power or moving to a calling area, and selects and broadcasts the most advantageous base station (best reception level, etc.) for making and receiving calls. This channel is used to determine whether or not the calling area has changed based on location information, and to cause the mobile station to issue a location registration request. The number of radio frequencies in the entire BCCH channel system affects the start-up operation time after the mobile station is powered on and the location registration request control time when moving to a paging area. It is advantageous because it can be shortened because it is not necessary.

On the other hand, with the PCH channel, the exact same incoming signal is transmitted from multiple base stations within the calling area to the mobile station, so it is better to transmit all at once using the same radio frequency at the same time. It will be used effectively.

Therefore, the conventional mobile communication systems are BCCH and PC.
By standardizing the radio frequency of the H channel and repeatedly using the radio frequency for a plurality of calling areas that make up the entire service area, as shown in FIG. 2, the minimum radio frequency is allocated. Under such a radio frequency arrangement, the radio control station shown in Figure 1, which centrally controls multiple base stations within a calling area, sends broadcast signals of the BCCH channel on the same radio frequency so as not to collide with each other, as shown in Figure 3. In addition to the sequential transmission synchronization control function necessary for transmitting PCH channel signals, the baseband bit synchronization control function necessary for simultaneous multi-station transmission of incoming signals on the PCH channel must be provided.

(Problem to be Solved by the Invention) The BCCH and PCH control channels in the above mobile communication system are configured to sequentially transmit broadcast signals and simultaneously transmit incoming signals in transmission slots determined for each base station. Therefore, it was necessary for the radio control station that makes up the paging area to have a synchronous control function that centrally controls each base station under its control and transmits sequentially/simultaneously to multiple stations, and the paging areas are different, making it impossible to implement synchronous control. The radio frequency had to be changed for each radio control station.

In order to solve the above-mentioned drawbacks, the present invention prepares one radio frequency that is common throughout the service area exclusively for the BCCH channel, and transmits broadcast signals from each base station to mobile stations at mutually independent random cycles. At the same time, through this broadcast signal, any radio frequency used for the PCI and 5CCH channels (for example, a free communication channel (TCH:
The purpose of this invention is to construct an economical system that does not have a synchronization control function and to improve the utilization rate of radio frequencies used for control channels by notifying mobile stations of traffic channels (traffic channels).

(Means for Solving the Problems) A feature of the present invention is a mobile communication system that configures a wireless channel between a mobile station and base stations forming a wireless zone. A broadcast control channel that broadcasts system information such as location information to the mobile station, an incoming control channel that transmits incoming signals from multiple base stations in the calling area to the mobile station, and a In a control channel configuration method for mobile communication equipped with a base station individual control channel for transmitting and receiving connection signals such as incoming call responses and outgoing signals, the radio frequencies of the above-mentioned broadcasting control channel and receiving control channel are set to different frequencies, and the broadcasting control channel is set to different frequencies. The radio frequency of the control channel for broadcasting is shared by multiple base stations, and the signal of the control channel for broadcasting is transmitted from each base station to the mobile station at random time intervals. The radio frequency and base station number of the station-specific channel are broadcast to the mobile station, and the mobile station uses the radio frequency of the base station notified by the signal with the highest reception level among the signals received during a certain period of time for connection. A method for configuring control channels in mobile communications for transmitting and receiving signals.

(Operation) The present invention transmits broadcast control signals at random intervals from each base station, and the receiving (mobile station) side determines the maximum signal that can be correctly received (this is a stochastic event) without collision based on the reception information. The synchronization control that was conventionally required at each base station is not required.

(Embodiment) The radio frequencies of the BCCH channel and the PCI channel are separated, and the former radio frequency is arranged so as to be commonly used by all base stations within the service area, as shown in FIG. 4(a). Furthermore, as shown in FIG. 4(b), the latter radio frequency is individually allocated and repeatedly used for the radio zone constituted by each base station.

B(:C:l(The radio frequency of the channel is assigned in common to all base stations within the service area, so each base station is assigned an independent channel so that the broadcast signals sent by each base station do not collide each time. Broadcast signals are transmitted at random intervals.In order to realize this random transmission, each base station creates a transmission slot cycle T for counting the transmission interval of broadcast signals, as shown in Fig. 5. The inter-base station slot phases of the transmission slots created by each base station may be different from each other.Each base station has the function of counting the number of transmission slots and the function of generating uniform random numbers. The notification signal is transmitted at a transmission interval equal to the number of slots corresponding to the random number r.

FIG. 6 is a broadcast/termination control sequence showing the relationship in which a mobile station receives and processes broadcast signals and incoming signals transmitted by a base station. The broadcast signal transmitted by the base station includes radio frequency information (Fp) of the PCI channel for the mobile station to wait for incoming calls, and radio frequency information (Fp) of the SCC:H channel for transmitting and receiving connection signals such as incoming call responses and outgoing signals.
Fs) is included.

These radio frequencies Fp and Fs are fixedly assigned to each base station as shown in FIG. 4(b), or
Alternatively, if there is no available radio frequency, the PCI (and 5CCH channel) may be used as the PCI (and 5CCH channel) until an empty TCH channel is available for communication, as shown in the control sequence in Figure 6. It is assumed that the radio frequencies (Fp, Fs) of the channels may be common.

On the other hand, the mobile station stores the radio frequency Fb of the BCCH channel in its non-volatile memory, and when the power is turned on at 08:00, it reads out this radio frequency Fb, switches the synthesizer of the transmitter/receiver, and calculates the reception time using equation (2) described later. During Tr, the broadcast signals randomly transmitted from each base station and their reception levels are stored. After the reception time Tr has elapsed, the radio frequency of the PCI channel of the base station notified by the broadcast signal with the highest reception level is stored. Switch the synthesizer to Fp and wait for an incoming signal.

This standby is performed inside the PCI signal from the base station.
If the CH display disappears, it means that there is no longer any free TCH available for TCH communication that has been used as a PCI channel, so switch the synthesizer to the radio frequency Fb of the BCCH channel and use it for other base stations. Select a station. Furthermore, when the standby station receives an incoming call signal for a medium call, it switches the synthesizer to the radio frequency Fs of the SCCH channel and transmits an incoming call response signal.

Although not shown in the control sequence of FIG. 6, when a mobile station transmits a location registration request signal or an origination signal to a base station, the 5CCH Switch the synthesizer to the radio frequency Fs of the channel and send out the corresponding signal.

The mobile station will receive the radio waves transmitted by each base station by the above random transmission, but if multiple base stations transmit this broadcast signal at the same time, the signals will collide, and the multiple base stations that have collided with each other's signals will collide. The notification from the mobile station to the mobile station will fail.

Therefore, the mobile station continues to receive the broadcast signal for the reception time determined by equation (2) below until the probability of failing to receive the broadcast signal (non-reception rate F) is expected to reach a specified value or less.

If the number of times the broadcast signal is received and the collision probability are R and C, respectively, then the non-reception rate F of the broadcast signal is equal to the probability of collision R times in a row, so the non-reception rate F=CI'' (1). Depending on the number of signal receptions R, the reception time Tr of the aforementioned notification signal is: Since the number of transmissions n is Poisson distributed, here, E:
The average number of transmissions per unit time is given to the number of base stations whose radio waves reach the mobile station. On the other hand, as shown in Fig. 7, a collision of broadcast signals is considered to occur when one or more broadcast signals are transmitted by another base station during an interval τ that is twice the incoming signal length t transmitted by the base station of interest. Therefore, the collision probability C of the notification signal in equation (3) is estimated as follows.

Randomness of Poisson's arrival (Basic mathematics selection book "Queuing")
From multiple base stations (Base stations i, i+1, .
-=, i+ -1 station) is given a signal during the time interval τ.

Now, if , the number of transmission occurrences per unit time for all base stations (k stations) whose radio waves arrive at the mobile station is 1/(TX
<r>)) The traffic λt added to the BCCH channel radio frequency where the existing mobile station is located is shown in Figure 8. The probability that the signal will not be received by the mobile station due to collision with transmissions from other base stations is calculated using equations (1), (4), and (6). When the number of times the notification signal is received is R = 2, the non-reception rate F is approximately 0.
．． If it is assumed that the same quality of service as the conventional technology can be obtained in the case of 001, the BCCH is adjusted such that the traffic added to the BCCH channel radio frequency becomes 0.016 or less.
It is sufficient to transmit a broadcast signal of the CH channel.

For example, the average interval of broadcast signals transmitted by each base station is determined to be 1 second so that the broadcast signal reception time Tr of the mobile station determined by equation (2) is approximately several seconds.

At this time, if the transmission slot period T = 0.1 seconds in equation (5), the average of uniform random numbers generated by each base station <r> = 1
Operate so that it becomes 0. In addition, the signal speed of the BCCH channel is 300kbps, and the information amount of the broadcast signal is 300kbps.
When requesting bits/signal, broadcast signal length t=0.0
01 seconds, so from equation (7), it is sufficient to design a wireless zone such that the number of base stations from which radio waves reach the mobile station is 16.

In addition, the utilization rate of the radio frequency of the BCCH channel in the present invention is calculated as follows: Broadcast signal length (1) ÷ Average interval of broadcast signals (Tx<r>)
In the above specific example, it is 0.001, but since this radio frequency can be used commonly by base stations throughout the service area, in a very small wireless zone system such as 100,000 base stations nationwide, it is possible to use the entire service area. The rate becomes 100,
The usage rate is extremely high and it is considered to be effective.

In addition, since the radio frequencies of PCH and 5CCH channels corresponding to each base station can be broadcast through the BCCH channel established with the mobile station, it is possible to easily realize a control channel configuration that is shared with vacant TCH channels. This can contribute to the effective use of

(Effects of the Invention) By applying the present invention, one radio frequency common to the entire service area is prepared exclusively for the BCCH channel, and broadcast signals are transmitted from each base station to a mobile station at mutually independent random cycles. At the same time, this broadcast signal can be used to transmit any radio frequency used for the PCI and 5CCH channels (for example, a free communication channel (TCH: Tra
ffic Channel) to the mobile station, it is possible to construct an economical mobile communication system that does not have a synchronization control function.

Furthermore, since the radio frequency used for the control channel can be shared with the radio frequency of the TCH channel, efficient use of the radio frequency without traffic division loss can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a station configuration of a mobile communication system to which the present invention is applied, FIG. 2 is a diagram showing a radio frequency arrangement of a calling area within a service area in a conventional embodiment, and FIG. FIG. 4 is a diagram showing the radio frequency arrangement of base stations within a service area in an embodiment of the present invention. FIG. FIG. 6 is a diagram showing a transmission slot configuration for random transmission, explaining a state in which a base station transmits a broadcast signal at random intervals. FIG. FIG. 7 is a diagram illustrating a collision period of broadcast signals, illustrating a period in which signals collide when a plurality of base stations randomly transmit broadcast signals in an embodiment of the present invention. FIG. 8 is a diagram showing a non-reception rate in which a mobile station cannot receive a broadcast signal in an embodiment of the present invention. 1 to m; base station; 10; radio control station; 20; mobile station. Fan Bat Figure 1 Cedar 17 Zuri 1

Claims (1)

[Claims] A mobile communication system that configures a wireless channel between a mobile station and a base station forming a wireless zone, in which system information such as location information is transmitted from each of a plurality of base stations to the mobile station. An announcement control channel for broadcasting, an incoming control channel for transmitting incoming signals from multiple base stations in a calling area to a mobile station, and a connection channel for incoming call responses, outgoing signals, etc. between the base station and mobile station. In a control channel configuration method for mobile communication equipped with a base station individual control channel for transmitting and receiving signals, the radio frequencies of the broadcasting control channel and the receiving control channel are set to different frequencies, and the radio frequency of the broadcasting control channel is set to multiple frequencies. The broadcast control channel signal is shared by the base stations and transmitted from each base station to the mobile station at random time intervals, and through this signal, the radio frequency of the incoming control channel and the base station individual control channel and the base station A mobile station characterized in that the number is broadcast to a mobile station, and the mobile station transmits and receives a connection signal on the radio frequency of the base station notified by the signal with the highest reception level among the signals received during a certain period of time. Control channel configuration method in communications.