JP2000333246A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To display possible return to a relay communication mode via a base station or to attain automatic restoration to the mode in the case two mobile stations communicate in a direct communication mode. SOLUTION: In the radio communication system, a base station includes discrimination data used for discrimination as to whether or not a mobile station is present in a communication area of the base station in a signal sent by an antenna 18 to each mobile station. A bit error rate detection section 39 of the mobile station detects a bit error on the basis of the discrimination data and a reception level detection section 38 detects a reception level. A 3rd discrimination section 42 compares the detected bit error rate and the detected reception level with a reference value or a reference level and discriminates whether or not restoration to the relay communication mode is possible. When the restoration is possible, a display section 45 displays it. Furthermore, after prescribed communication with respect to the restoration with a mobile station of a communication opposite party, a control section 48 switches frequencies of a modulation section 35 and a reception demodulation 39 into frequencies (f1 for transmission frequency and f2 for reception frequency) for relay communication.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radio communication system, and more particularly, to a radio communication system including one base station and a plurality of mobile stations, wherein one mobile station and another mobile station are connected to a base station. The present invention relates to a return from a direct communication mode in which direct communication is performed without relaying a station to a relay communication mode in which communication is performed by relaying a base station.

[0002]

2. Description of the Related Art In a wireless communication system including one base station and a plurality of mobile stations, when one mobile station communicates with another mobile station, the communication is usually performed by relaying the base station. This communication mode is referred to as “relay communication mode”. On the other hand, there is a case where these mobile stations move from an area where communication with the base station is possible, and perform communication in a situation away from the control of the base station. This communication mode is referred to as “direct communication mode”. In the case of the direct communication mode, a dedicated carrier signal having a different frequency from the relay communication mode is usually used. In a conventional wireless communication system, an operation unit for switching between the relay communication mode and the direct communication mode is provided in a communication device on the mobile station side, and the switching operation is performed by human judgment.

[0003]

However, in the case of the conventional mode setting method based on human judgment, once the mode is directly switched to the direct communication mode due to being out of the communicable area with the base station, the frequency of the carrier signal is reduced. Is dedicated, it cannot be recognized even if it enters the area where it can communicate with the base station again. For this reason, a situation may occur in which communication is directly performed in the direct communication mode even when the apparatus can actually return to the relay communication mode. Therefore, in a situation where it is possible to return to the relay communication mode even when shifting to the direct communication mode, it is desired to have a function of causing the operator to recognize the fact or automatically returning to the relay communication mode. An object of the present invention is to provide a wireless communication system having such a function.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a radio communication system comprising a base station and a plurality of mobile stations, and communicating with a signal formed by a synchronization burst, a communication burst and a control burst. In the signal transmitted to each mobile station, the determination data used for determining whether the mobile station is present in the communication area of the base station is included, and the bit error rate of the determination data is detected in the mobile station. Bit error rate detecting means, a discriminating means for comparing and discriminating the detected bit error rate with a reference value, and a display means for displaying a result of the comparison discrimination by the discriminating means. When the bit error rate is determined to be equal to or less than the reference value by the determination means in the direct communication mode for performing direct communication without performing, the display means displays the bit error rate on the display means. And there is provided a wireless communication system.

Alternatively, the mobile station is provided with level detecting means for detecting a reception level of a signal from a base station in place of the bit error rate detecting means, and the discrimination means for detecting the detected reception level and the reference level. And when the reception level is determined to be equal to or higher than the reference level, a display may be made on the display means.

Alternatively, the mobile station is provided with level detecting means for detecting a reception level of a signal from a base station together with the bit error rate detecting means, and the detected reception level and the reference level are also discriminated. When the bit error rate is equal to or less than a reference value and the reception level is equal to or more than the reference level, the information may be displayed on the display means.

Alternatively, the mobile station is provided with communication mode switching means for switching between a relay communication mode in which communication is performed between mobile stations by relaying the base station and a direct communication mode in which direct communication is performed between mobile stations, When the bit error rate is determined to be less than or equal to the reference value, or when the reception level is determined to be greater than or equal to the reference level, or when both are determined, the communication mode switching means switches from the direct communication mode to the relay communication mode. The mode may be switched.

[0008] Further, the discrimination data is included in the control burst and transmitted.

Further, the control burst including the discrimination data is always transmitted except when transmitting the synchronization burst and the communication burst.

The communication mode switching means switches to a relay communication mode for a preset period after transmitting a control burst including end information during communication in the direct communication mode. During the period, a signal from the base station including the determination data is received.

The transmission of the control burst including the end information is defined as one transmission.

Further, a data generating means is provided in the mobile station, and when the bit error rate is determined to be equal to or less than the reference value, or when the reception level is determined to be equal to or more than the reference level, or both of them are determined. In this case, the data generating means generates data indicating that the mobile station can return to the relay communication mode, and transmits the data to the mobile station of the communication partner.

[0013] Further, data indicating that it is possible to return to the relay communication mode is transmitted while being included in a synchronization burst.

Further, the mobile station is provided with a timer means for outputting a predetermined signal after a lapse of a predetermined time, and an alarm means activated by a signal from the clock means, wherein the bit error rate is less than a reference value in the discriminating means. When the reception level is determined to be equal to or higher than the reference level, or when both are determined, the alarm means is activated when the predetermined time has elapsed after the determination.

[0015]

Embodiments of the present invention will be described below with reference to the drawings based on embodiments. FIG. 1 is a conceptual explanatory diagram of a system configuration of a wireless communication system according to the present invention.
Is a base station (A) in the wireless communication system according to the present invention.
FIG. 3) is a main block diagram showing an embodiment of each configuration of the mobile station (FIG. 3B), FIG. 3 is an explanatory diagram of a transmission signal, and FIG. 4 and FIG.

First, the concept of the system configuration of the wireless communication system according to the present invention will be described with reference to FIG. As shown, the wireless communication system according to the present invention is formed by one base station 1 and a plurality of mobile stations 2 to 4. As a carrier signal used for communication between the base station and each mobile station, the same frequency is used for both transmission and reception, and a method of changing the frequency for each mobile station, or from the base station 1 to each of the mobile stations 2 to 4 as shown in FIG. Is transmitted at a common frequency f1 (first carrier signal), and transmission from each of the mobile stations 2 to 4 to the base station 1 is performed at another common frequency.
f2 (second carrier signal). The following description is based on FIG. As shown in FIG. 1, communication between mobile stations (direct communication mode) uses a dedicated frequency f3 (third carrier signal) different from the above. Also,
The modulation system of the wireless communication system is digital modulation, and is mainly intended for transmitting and receiving voice signals (communication).

Next, the configuration of the base station 1 and the mobile stations 2 to 4 in FIG. 1 will be described with reference to FIG. In addition, each mobile station 2
4 have the same configuration. Base station 1 in FIG.
In the figure, reference numeral 11 denotes a receiving antenna, which receives transmission signals of frequency f2 from the mobile stations 2 to 4. Reference numeral 12 denotes a reception demodulation unit, which demodulates data from the received signal of the frequency f2. The demodulated data is processed by an audio signal in an audio processing circuit 13,
A voice is emitted from a speaker (SP) 14. Also, the signal from the reception demodulation unit 12 is input to the data generation unit 15. The data generator 15 is a signal from the reception demodulator 13 and a base station voice signal.
Based on S1, data in the format shown in FIG. 3A (described later) is generated under the control of the control unit 19. Based on the signal from the data generation unit 15, the modulation unit 16 performs digital modulation processing.
Sent to The frequency of this transmission signal is f1. The control unit 19 sets the reception frequency f2 and the transmission frequency of the reception demodulation unit 13 to f1.
And so on.

Next, the mobile station shown in FIG. 2B receives the first carrier signal f1 from the base station 1, transmits the second carrier signal f2 to the base station 1, and directly communicates with the mobile station. For transmission / reception using a carrier signal (third carrier signal) of frequency f3 in the communication mode, a dual-purpose transmission / reception antenna 31 is used, and the transmission / reception is switched by a transmission / reception switching circuit 32.
The transmission / reception switching circuit 32 is switched by the operation of the operation unit 33, and based on the operation, the control unit 48 sets the transmission unit side for transmission and the reception demodulation unit side for reception. As a transmission function, the second carrier signal f2 to the base station 1 or the third carrier signal f3 at the time of direct communication with the mobile station is digitally modulated by the data generator 34 for generating required data. The signal is transmitted via the modulation unit 35, the transmission unit 36, the transmission / reception switching circuit 32, and the transmission / reception antenna 31. The data generator 34 generates data in the format shown in FIG. 3B (described later) under the control of the controller 48 based on the mobile station audio signal S2.

In the modulation section 35, the carrier frequency is set under the control of the control section 48 to the second carrier signal f2 in the relay communication mode, and to the third carrier signal f2 in the direct communication mode.
Set to f3. As a receiving function, the first carrier signal f1 or the third carrier signal f3 is data-demodulated by the reception demodulation unit 37. This demodulated data or transmission / reception switching circuit
Functional blocks relating to various detections, data discrimination, and the like based on the received signal from 32 are provided as shown in the figure, but these will be described in the following description of operation. In addition,
The control unit 48 controls those shown in the figure, and controls a series of detections or determinations in the operation description to be described later. Although not shown, the output signal Sa of the receiving / demodulating unit 37 is used for reproducing a call voice (voice processing circuit, speaker, etc.).

Next, the form (format) of the transmission signal shown in FIG. 3 will be described. FIG. 3A shows a base station transmission signal, and FIG. 3B shows a mobile station transmission signal. In the figure, SB is a synchronization burst, TCH is a speech burst (speech voice signal), and CCH is a control burst. Hereinafter, these bursts are referred to as SB, TCH, and CCH.
As shown in the drawing, the base station 1 transmits the SB twice or three times (three times in the figure), transmits the required number of times (two times in the figure), and thereafter continuously transmits the CCH. This CCH, include discrimination data subjected to the determination of whether the mobile station is present in the communication area of the base station. When a call is again made with the mobile station, the signal is transmitted again from the SB.

On the other hand, as shown in the figure, the mobile station transmits the SB two or three times (three times in the figure), transmits the required number of times (two times in the figure), and finally transmits the CCH, similarly to the base station. Is transmitted once. Here, information (message) required in the process of returning from the direct communication mode to the relay communication mode is stored in the SB.
Include data from For example, it is possible to return to the relay communication mode, a return request, a return permission, and the like. Also, the CCH includes the data of the end information. FIG. 3 (C), (D), (E)
Shows a specific configuration example of the above TCH, CCH, and SB. In the figure, P is a preamble, SW is a synchronization word, G
Is a guard. The numbers in parentheses are bit examples. Data of said discrimination data, and necessary information in the process of returning to the indirect communication mode (message) is inserted into the "Parameters" portion.

Next, the operation of the present invention will be described with reference to FIGS.
A description will be given based on the operation flowchart of FIG. In the following, the mobile station a2 (hereinafter, mobile station a) and the mobile station b3 (hereinafter, mobile station b) in FIG. 1 return from the direct communication mode to the relay communication mode via the base station. A case will be described as an example. The ST numbers in the description indicate the steps in FIG. 4 or FIG. First, a description will be given based on FIG. Standby state under direct communication mode (ST
When the mobile station a in 1) originates a call, first, the first determining unit 40 determines whether or not a synchronous burst signal (SB) has been received from another station (ST2). The determination of "received" will be described later, and here, the determination of "not received" (ST2-N). In accordance with the determination of "no reception", the control unit 48 displays the fact on the display unit 45 (ST3). According to the operation of the operation unit 33 by the operator who has confirmed this display, the transmission / reception switching circuit (SW)
32 is turned on (transmitted) and set to a calling state.

The operation unit 33 outputs a corresponding status signal S3.
Is output. Based on the state signal S3, the second determination unit 41
Then, it is determined that the calling state (SW-ON) has been set (ST4-Y). In accordance with this determination, the control unit 48 causes the data generation unit 34 to generate a synchronization burst signal (SB) (ST5). If the determination by the second determination unit 41 is continued and the transmission / reception switching circuit 32 is in the ON state (ST6-Y), the control unit
48 is an operator's voice signal (communication signal) S2 via a microphone or the like.
The TCH data based on is also generated by the data generator 34 (ST7). The generation of the TCH data continues while the transmission / reception switching circuit 32 is on. The data of the above SB and TCH are output from the data generator 34 in the format of FIG.
5. The signal is transmitted from the antenna 31 to the mobile station b via the transmission unit 36 and the transmission / reception switching circuit 32. During this transmission, the control unit
48 sets the modulation unit 35 so that the carrier frequency is f3.

When the call to the mobile station b is completed and the operator turns off (receives) the transmission / reception switching circuit 32 (ST6-N), the operation unit 33 outputs a corresponding status signal S3. Based on the state signal S3, the second determination unit 41 determines whether the switching circuit 32 is off (ST6-N). According to this determination, the control unit
48 generates CCH (control burst) data including call termination information from the data generator 34, and modulates it as final data.
The data is transmitted via 35 or the like (ST8). The transmission / reception switching circuit 32
Is controlled by the control unit 48 so as to be set to the reception state after the transmission of the CCH data after the OFF operation by the operation unit 33.
After transmitting the CCH data, the mobile station a switches the communication mode (ST9). Specifically, the control unit 48 controls the reception and demodulation unit 37.
Is set to f1 and the transmission signal from the base station 1 is received (relay communication mode) (ST10). If the signal can be received, the signal is sent to the antenna 31 and the transmission / reception switching circuit.
The signal is input to the reception demodulation unit 37 via 32. The reception level is detected by the level detection section 38 based on the input signal, and the bit error rate of the reception data is detected by the bit error rate detection section 39 (ST10). This bit error rate is detected based on the discrimination data included in the CCH data constantly transmitted from the base station except during a call.

After receiving the signal from the base station 1 for a predetermined time, the mobile station a switches the communication mode again and returns to the direct communication mode with the mobile station b (ST12). On the other hand, based on the detected reception level and bit error rate, the third determination unit 42 compares the reception level at the reference level or higher, or the bit error rate at the reference rate or lower, or both,
Judgment as to whether or not return to relay communication mode is possible (ST1
3). For this comparison and determination, the third determination unit 42 stores in advance the data of the reception level and the bit error rate that serve as references. When the reception level is equal to or higher than the reference level, or when the bit error rate is equal to or lower than the reference rate (reference value), or when both are satisfied, the mobile station a exists in the communication area of the base station 1. Means that it is possible to return to the relay communication mode. Therefore,
If it is possible to return to the relay communication mode (ST13-Y), the control unit 48 causes the display unit 45 to display a message indicating that (return is possible) (ST14).

When it is determined that return to the relay communication mode is possible, the control unit 48 generates data indicating information indicating that "the mobile station a can return to the relay communication mode" from the data generation unit 34. Let it. The data is generated so as to be included in the SB data (ST15). The mobile station “a” will be called the mobile station “b” next time.
When transmitting the SB data, the generated SB data is transmitted (ST15). Although the above description has been made with a focus on the mobile station a, the same operation is performed for the mobile station b (ST1 to ST1).
Five). It is assumed that the mobile station b is also determined to be able to return to the relay communication mode. Therefore, the mobile station a that has received the next transmission signal from the mobile station b (ST2-Y) can know from the SB data that "the mobile station b can return to the relay communication mode". Specifically, the received S
The B data is subjected to discrimination in the fourth discriminating section 43, and it is discriminated whether or not the data includes information of "can return to the relay communication mode" (ST16). If it is possible to return (ST16-Y), the control unit 48 causes the display unit 45 to display a message indicating that (return to the partner station is possible) (ST17). With this display, the operator of the mobile station a can check the mobile station a and the mobile station b.
Both recognize that it is possible to return to the relay communication mode.

Subsequently, the mobile station a receives the TC from the mobile station b.
H data is received for a required period (ST18), and the communication mode is switched to the relay communication mode when the CCH data including the end information is received (ST19-Y) (ST9). The fifth determining unit 44 determines whether or not the CCH data including the end information is received. The operator of the mobile station b also knows from the display that "the mobile station a can return to the relay communication mode" from the SB data of the next transmission signal from the mobile station a. With this display, each operator of the mobile station a and the mobile station b recognizes that it is possible to return to the relay communication mode. When returning to the relay communication mode, the operation unit 33 is manually operated based on agreement between the two operators, and the transmission / reception switching circuit 32 is switched to return.

The following functions may be provided in each mobile station. This is the case where the above-mentioned call has been completed and the standby state has continued for a predetermined time, and it is determined that return to the relay communication mode is possible (ST13-Y), and the modulation unit 35 and the reception demodulation unit When 37 is set to the direct communication mode, an alarm is issued to the operator. Specifically, when the standby state is set (ST4-N), the control unit 48 activates the timer unit 46 that outputs a predetermined signal after a predetermined time has elapsed (ST20). When the timer section 46 times out, the alarm 47 is activated based on the output signal (ST21-Y) (ST22). The alarm 47 may be displayed on the display unit 45, an LED display, or an alarm sound generated by a speaker or the like.

Next, FIG. 5 will be described. FIG. 4 shows a function for displaying the effect of being able to return to the relay communication mode.
On the other hand, FIG. 5 further develops the function of FIG. 4 and automatically returns to the relay communication mode. FIG. 2 is a block diagram. The description of the operation part common to FIG. 4 is omitted, and FIG. 5 describes the operation flow of the automatic return. It is the mobile station a that first issued a message indicating that it is possible to return from the direct communication mode to the relay communication mode, and the mobile station b first received the message and displayed it (ST31 to ST31). 34). Also, the mobile station b transmits a message to the effect that the mobile station b can return to the relay communication mode to the mobile station a (ST15).

Therefore, in the mobile station b which first receives the resumable message, the data generator 34 generates a "return request" message in the SB (ST37), and transmits this next time. The “return request” is a message at a stage next to the “returnable”. In FIG. 5, there are ST35 and ST36 before the above-mentioned step (ST37), which are necessary for the operation flow of the automatic return. At this stage, the reception SB (that is, the transmission from the mobile station a) is in progress. There is no message of "return request" (ST35-N), and there is no message of "return permission" (stage following "return request") (ST36-N).

The mobile station a, which has received the transmission signal from the mobile station b, sends a "return request" message of the mobile station b to the fourth station.
(ST33-Y, ST35-Y), and the "return request" is displayed on the display unit 45 (ST38). In response to the “return request” message, the mobile station “a”
Further, a message of “return permission” is included in the SB and generated (ST39), and transmitted next time. When the "return permission" message is transmitted, the fourth determination unit of the mobile station a
43 is determined to have been transmitted (ST40-Y). Based on the determination, the control unit 48 of the mobile station a returns to the relay communication mode (ST41). Specifically, the reception demodulation unit 37 is set to the reception frequency f1, and the modulation unit 35 is set to the transmission frequency f1.
Set to f2. For the other mobile station b, the received S
It is determined that there is a "return permission" message in B (fourth determination unit 43 of mobile station b) (ST36-Y). Based on the determination, the control unit 48 of the mobile station b returns to the relay communication mode (ST41). As described above, both the mobile station a and the mobile station b automatically return to the relay communication mode, and thereafter, communication is performed in the same mode.

[0032]

As described above, according to the present invention, in a wireless communication system including one base station and a plurality of mobile stations, when the mobile stations communicate with each other in the direct communication mode, It is displayed that it is possible to return to the relay communication mode via the base station after entering the area where communication with the station is possible, or it is possible to automatically return to the relay communication mode.
As a result, once switching to the direct communication mode, the carrier signal has a dedicated frequency, so that it cannot be recognized even if it enters the area where it can communicate with the base station again. Thus, the performance of the wireless communication system can be improved.

[Brief description of the drawings]

FIG. 1 is a conceptual explanatory diagram of a system configuration of a wireless communication system according to the present invention.

FIG. 2 is a main part block diagram showing one embodiment of each of a base station (FIG. A) and a mobile station (FIG. B) in a wireless communication system according to the present invention.

FIG. 3 is an explanatory diagram of a transmission signal.

FIG. 4 is an operation flowchart in one embodiment of the wireless communication system according to the present invention.

FIG. 5 is an operation flowchart in another embodiment of the wireless communication system according to the present invention.

[Explanation of symbols]

 1 Base station 2, 3, 4 Mobile station 11, 18, 31 Antenna 12, 37 Reception and demodulation unit 13 Voice processing circuit 14 Speaker 15, 34 Data generation unit 16, 35 Modulation unit 17, 36 Transmission unit 19, 48 Control unit 32 Transmission / reception switching circuit 33 Operation section 38 Level detection section 39 Bit error rate detection section 40, 41, 42, 43, 44 Discrimination section 45 Display section 46 Timer section 47 Alarm

Claims (11)

[Claims] 1. A radio communication system comprising a base station and a plurality of mobile stations and communicating with signals formed by a synchronization burst, a communication burst, and a control burst, a signal transmitted from the base station to each mobile station. In the meantime, while including the determination data for determining whether the mobile station is present in the communication area of the base station, the mobile station, the bit error rate detection means for detecting the bit error rate of the determination data, Direct communication in which a discriminating means for comparing and discriminating the detected bit error rate with a reference value and a display means for displaying a result of the comparison discrimination by the discriminating means are provided so that the mobile stations communicate directly without relaying the base station. While in mode,
A wireless communication system characterized in that when the bit error rate is determined to be equal to or less than a reference value by the determination means, the information is displayed on the display means. 2. The mobile station according to claim 1, further comprising: a level detector for detecting a reception level of a signal from a base station in place of the bit error rate detector. 2. The method according to claim 1, wherein when the reception level is determined to be equal to or higher than the reference level, the information is displayed on the display unit.
A wireless communication system as described. 3. The mobile station is provided with level detection means for detecting a reception level of a signal from a base station in combination with the bit error rate detection means, and the discrimination is also made between the detected reception level and the reference level. 2. The wireless communication device according to claim 1, wherein the determination is performed by the means, and when the bit error rate is determined to be equal to or lower than a reference value and the reception level is determined to be equal to or higher than the reference level, the information is displayed on the display means. Communications system. 4. The mobile station is provided with communication mode switching means for switching between a relay communication mode in which communication is performed between mobile stations by relaying the base station and a direct communication mode in which direct communication is performed between mobile stations. When the bit error rate is determined to be equal to or less than the reference value in the determination means, or when the reception level is determined to be equal to or more than the reference level, or when both are determined, relaying from the direct communication mode is performed by the communication mode switching means. 4. The wireless communication system according to claim 1, wherein the mode is switched to a communication mode. 5. The radio communication system according to claim 1, wherein the discrimination data is included in the control burst. 6. The control burst including the discrimination data is always transmitted except when transmitting the synchronization burst and the communication burst. A wireless communication system as described. 7. The communication mode switching means switches to a relay communication mode for a preset period after transmitting a control burst including call termination information during communication in the direct communication mode. 5. The radio communication system according to claim 1, wherein a signal from a base station including the discrimination data is received during the same period. 8. The wireless communication system according to claim 7, wherein the transmission of the control burst including the call termination information is performed once. 9. A data generating means is provided in the mobile station, and when the bit error rate is determined to be equal to or less than the reference value, or when the reception level is determined to be equal to or more than the reference level, or both of them are determined. The data generating means generates data indicating that the mobile station in the determination can return to the relay communication mode when the determination is made, and transmits the data to the mobile station of the communication partner. ,
The wireless communication system according to claim 2 or 3. 10. The wireless communication system according to claim 9, wherein data indicating that the mobile station can return to the relay communication mode is included in a synchronization burst. 11. A mobile station, comprising: a timer means for outputting a predetermined signal after a predetermined time has elapsed; and an alarm means activated by a signal from the clock means. When determined as below, or when the reception level is determined to be equal to or higher than the reference level, or when both are determined, the alarm means is operated when the predetermined time has elapsed after the determination. The wireless communication system according to claim 1, 2 or 3, wherein